Last data update: Apr 29, 2024. (Total: 46658 publications since 2009)
Records 1-30 (of 46 Records) |
Query Trace: Pham CD[original query] |
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Detection of fungal DNA in human body fluids and tissues during a multistate outbreak of fungal meningitis and other infections.
Gade L , Scheel CM , Pham CD , Lindsley MD , Iqbal N , Cleveland AA , Whitney AM , Lockhart SR , Brandt ME , Litvintseva AP . Eukaryot Cell 2013 12 (5) 677-83 Exserohilum rostratum was the major cause of an outbreak of fungal infections linked to injections of contaminated methylprednisolone acetate. Because almost 14,000 persons were exposed to product that was possibly contaminated with multiple fungal pathogens, there was unprecedented need for a rapid throughput diagnostic test that could detect both E. rostratum and other unusual agents of fungal infection. Here we report development of a novel PCR test that allowed for rapid and specific detection of fungal DNA in cerebrospinal fluid (CSF), other body fluids and tissues of infected individuals. The test relied on direct purification of free-circulating fungal DNA from fluids and subsequent PCR amplification and sequencing. Using this method, we detected Exserohilum rostratum DNA in 123 samples from 114 case-patients (28% of 413 case-patients for whom 627 samples were available), and Cladosporium DNA in one sample from one case-patient. PCR with novel Exserohilum-specific ITS-2 region primers detected 25 case-patients with samples that were negative using broad-range ITS primers. Compared to fungal culture, this molecular test was more sensitive: of 139 case-patients with an identical specimen tested by culture and PCR, E. rostratum was recovered in culture from 19 (14%), but detected by PCR in 41 (29%), showing a diagnostic sensitivity of 29% for PCR compared to 14% for culture in this patient group. The ability to rapidly confirm the etiologic role of E. rostratum in these infections provided an important contribution in the public health response to this outbreak. |
Novel strain of multidrug non-susceptible Neisseria gonorrhoeae in the USA
Reimche JL , Pham CD , Joseph SJ , Hutton S , Cartee JC , Ruan Y , Breaux M , Ivanof C , Joshi A , DeMartino M , Kirby JE , Barbee LA , Kersh EN , Roosevelt KA , Hsu KK . Lancet Infect Dis 2024 Unsuccessful treatment of gonorrhoea has not yet occurred in the USA, and cases of gonorrhoea that are non-susceptible to cephalosporins have been rare. In 2019, non-susceptibility to ceftriaxone conferred by the mosaic penA 60.001 allele was found in a Neisseria gonorrhoeae multilocus sequence type (MLST) 1901 isolate from Nevada.1 In this Correspondence, we present two additional US cases of the penA 60.001 allele identified in MLST 8123, an emerging international multidrug non-susceptible N gonorrhoeae lineage. Although these cases responded to ceftriaxone treatment, N gonorrhoeae isolates from the first known patient (case 1) demonstrated in-vitro non-susceptibility to ceftriaxone as well as non-susceptibility or resistance to drugs previously recommended for front-line treatment. | | In August, 2022, N gonorrhoeae grown from urine culture from a patient with urethritis in primary care in Massachusetts displayed non-susceptibility to cephalosporins (the minimum inhibitory concentrations were 1·0 μg/mL for ceftriaxone and >1·0 μg/mL for cefixime by agar dilution; the minimum inhibitory concentration for cefixime was 1·5 μg/mL by gradient strip) and azithromycin and resistance to ciprofloxacin, penicillin, and tetracycline (appendix pp 6–7). Antimicrobial susceptibility testing was done with gradient strips at the state public health laboratory Massachusetts and then confirmed via agar dilution at the US Centers for Disease Control and Prevention (CDC). The patient (case 1) had already been successfully diagnosed on nucleic acid amplification test (NAAT) with gonorrhoea and was given 500 mg ceftriaxone intramuscularly and asked to return to primary care where, 9 days after treatment, he was asymptomatic, had normal results during examination, and tested negative by urine culture and pharyngeal and rectal NAAT recommended by the Massachusetts sexually transmitted diseases programme to document N gonorrhoeae clearance from any site of infection. The patient reported that he had not travelled outside USA in the 60 days before onset of symptoms. He disclosed female sex worker contacts, but insufficient information was provided to trace the contacts. |
The enhanced gonococcal surveillance programme, Cambodia
Ouk V , Pham CD , Wi T , van Hal SJ , Lahra MM . Lancet Infect Dis 2023 23 (9) e332-e333 Antimicrobial resistance in Neisseria gonorrhoeae is a global public health threat, exemplified by increasing reports of isolates with high minimum inhibitory concentrations (MICs) to cephalosporin antibiotics, the last remaining first-line agent.1 Since 2015, there have been sporadic reports of N gonorrhoeae isolates with elevated ceftriaxone MIC values from several countries. The overwhelming majority of these isolates harbour the penA-60.001 allele (a gene encoding the gonococcal penicillin binding protein 2, associated with ceftriaxone resistance) and are closely related to the original described resistant strain, FC428.2, 3 An increase in the detection of such isolates from returned travellers was reported in the UK and Austria.3, 4 | | The Enhanced Gonococcal Antimicrobial Surveillance Programme (EGASP) uses standardised methods for antimicrobial resistance surveillance5 and was established in Cambodia in 2020. In 2021–22, N gonorrhoeae was isolated from 93 urethral specimens collected from symptomatic males in Cambodia where the clinical guidelines recommend a single oral 400 mg dose of cefixime. The N gonorrhoeae isolates were referred to the partnering WHO collaborating centre in Australia for confirmation and genomic analysis (see appendix pp 7–8). |
Mechanistic basis for decreased antimicrobial susceptibility in a clinical isolate of Neisseria gonorrhoeae possessing a mosaic-like mtr efflux pump locus (preprint)
Rouquette-Loughlin CE , Reimche JL , Balthazar JT , Dhulipala V , Gernert KM , Kersh EN , Pham CD , Pettus K , Abrams AJ , Trees DL , St Cyr S , Shafer WM . bioRxiv 2018 448712 Recent reports suggest that mosaic-like sequences within the mtr (multiple transferable resistance) efflux pump locus of Neisseria gonorrhoeae likely originating from commensal Neisseria sp. by transformation can increase the ability of gonococci to resist structurally diverse antimicrobials. Thus, acquisition of numerous nucleotide changes within the mtrR gene encoding the transcriptional repressor (MtrR) of the mtrCDE efflux pump-encoding operon or overlapping promoter region for both along with those that cause amino acid changes in the MtrD transporter protein were recently reported to decrease gonococcal susceptibility to numerous antimicrobials, including azithromycin (Azi) (Wadsworth et al. 2018. MBio. doi.org/10.1128/mBio.01419-18). We performed detailed genetic and molecular studies to define the mechanistic basis for why such strains can exhibit decreased susceptibility to MtrCDE antimicrobial substrates including Azi. We report that a strong cis-acting transcriptional impact of a single nucleotide change within the -35 hexamer of the mtrCDE promoter as well gain-of-function amino acid changes at the C-terminal region of MtrD can mechanistically account for the decreased antimicrobial susceptibility of gonococci with a mosaic-like mtr locus.IMPORTANCE Historically, after introduction of an antibiotic for treatment of gonorrhea, strains of N. gonorrhoeae emerge that display clinical resistance due to spontaneous mutation or acquisition of resistance genes. Genetic exchange between members of the Neisseria genus occurring by transformation can cause significant changes in gonococci that impact the structure of an antibiotic target or expression of genes involved in resistance. The results presented herein provide a framework for understanding how mosaic-like DNA sequences from commensal Neisseria that recombine within the gonococcal mtr efflux pump locus function to decrease bacterial susceptibility to antimicrobials including antibiotics used in therapy of gonorrhea. |
Genomic analysis of 1710 surveillance-based Neisseria gonorrhoeae isolates from the USA in 2019 identifies predominant strain types and chromosomal antimicrobial-resistance determinants
Reimche JL , Clemons AA , Chivukula VL , Joseph SJ , Schmerer MW , Pham CD , Schlanger K , St Cyr SB , Kersh EN , Gernert KM . Microb Genom 2023 9 (5) This study characterized high-quality whole-genome sequences of a sentinel, surveillance-based collection of 1710 Neisseria gonorrhoeae (GC) isolates from 2019 collected in the USA as part of the Gonococcal Isolate Surveillance Project (GISP). It aims to provide a detailed report of strain diversity, phylogenetic relationships and resistance determinant profiles associated with reduced susceptibilities to antibiotics of concern. The 1710 isolates represented 164 multilocus sequence types and 21 predominant phylogenetic clades. Common genomic determinants defined most strains' phenotypic, reduced susceptibility to current and historic antibiotics (e.g. bla (TEM) plasmid for penicillin, tetM plasmid for tetracycline, gyrA for ciprofloxacin, 23S rRNA and/or mosaic mtr operon for azithromycin, and mosaic penA for cefixime and ceftriaxone). The most predominant phylogenetic clade accounted for 21 % of the isolates, included a majority of the isolates with low-level elevated MICs to azithromycin (2.0 µg ml(-1)), carried a mosaic mtr operon and variants in PorB, and showed expansion with respect to data previously reported from 2018. The second largest clade predominantly carried the GyrA S91F variant, was largely ciprofloxacin resistant (MIC ≥1.0 µg ml(-1)), and showed significant expansion with respect to 2018. Overall, a low proportion of isolates had medium- to high-level elevated MIC to azithromycin ((≥4.0 µg ml(-1)), based on C2611T or A2059G 23S rRNA variants). One isolate carried the penA 60.001 allele resulting in elevated MICs to cefixime and ceftriaxone of 1.0 µg ml(-1). This high-resolution snapshot of genetic profiles of 1710 GC sequences, through a comparison with 2018 data (1479 GC sequences) within the sentinel system, highlights change in proportions and expansion of select GC strains and the associated genetic mechanisms of resistance. The knowledge gained through molecular surveillance may support rapid identification of outbreaks of concern. Continued monitoring may inform public health responses to limit the development and spread of antibiotic-resistant gonorrhoea. |
Assessing the national representativeness of estimates of antimicrobial resistant urogenital Neisseria gonorrhoeae in US men, Gonococcal Isolate Surveillance Project, 2008-2018
Nielsen KE , StCyr SB , Pham CD , Kreisel KM . Sex Transm Dis 2022 BACKGROUND: The percentage of Neisseria gonorrhoeae (GC) isolates with resistance or elevated minimum inhibitory concentrations (MICs) to antimicrobials has steadily increased. Current estimates are based on the Gonococcal Isolate Surveillance Project (GISP), a sentinel surveillance study of male GC in the United States. This analysis seeks to assess for adjustment prior to treating aggregated GISP estimates as nationally representative of all reported male urogenital infections. METHODS: We used multilevel regression with poststratification (MRP) to compute national estimates of the proportion of antimicrobial resistance (AMR - defined as exceeding MIC thresholds) in male GC using data from 2008-2018 GISP and case reports. Sensitivity analyses investigated the impact of analysis assumptions and unmeasured variables. We additionally produced estimates of 2018 AMR GC cases among US males. RESULTS: National estimates were consistent with unweighted estimates. The estimated proportion of incident AMR GC infections in men with urogenital GC in 2018 was 51.5% (95% CI: 50.1% - 52.9%), equating to an estimated 366,300 incident AMR GC infections in US men aged 15-39 years. Estimates of AMR for tested antimicrobials in male GC infections in 2018 ranged from 0.16% (95% CI: 0.08% - 0.24%) for ceftriaxone to 29.9% (95% CI: 28.6% - 31.1%) for ciprofloxacin. Sensitivity analyses revealed that unmeasured data on sex of sex partners could substantially impact weighted estimates. CONCLUSIONS: AMR among reported incident male urogenital GC infections remains rare for ceftriaxone, the current standard of care. Aggregated GISP data are generally representative of men in the US who are reported with urogenital gonorrhea. |
Phylogenomic Comparison of Neisseria gonorrhoeae Causing Disseminated Gonococcal Infections and Uncomplicated Gonorrhea in Georgia, United States.
Cartee JC , Joseph SJ , Weston E , Pham CD , Thomas JCth , Schlanger K , St Cyr SB , Farley MM , Moore AE , Tunali AK , Cloud C , Raphael BH . Open Forum Infect Dis 2022 9 (7) ofac247 Disseminated gonococcal infection (DGI) is a rare complication caused by the systemic dissemination of Neisseria gonorrhoeae to normally sterile anatomical sites. Little is known about the genetic diversity of DGI gonococcal strains and how they relate to other gonococcal strains causing uncomplicated mucosal infections. We used whole genome sequencing to characterize DGI isolates (n = 30) collected from a surveillance system in Georgia, United States, during 2017-2020 to understand phylogenetic clustering among DGI as well as uncomplicated uro- and extragenital gonococcal infection (UGI) isolates (n = 110) collected in Fulton County, Georgia, during 2017-2019. We also investigated the presence or absence of genetic markers related to antimicrobial resistance (AMR) as well as surveyed the genomes for putative virulence genetic factors associated with normal human-serum (NHS) resistance that might facilitate DGI. We found that DGI strains demonstrated significant genetic variability similar to the population structure of isolates causing UGI, with sporadic incidences of geographically clustered DGI strains. DGI isolates contained various AMR markers and genetic mechanisms associated with NHS resistance. DGI isolates had a higher frequency of the porB1A allele compared with UGI (67% vs 9%, P < .0001); however, no single NHS resistance marker was found in all DGI isolates. Continued DGI surveillance with genome-based characterization of DGI isolates is necessary to better understand specific factors that promote systemic dissemination. |
Characterization of a Neisseria gonorrhoeae Ciprofloxacin panel for an antimicrobial resistant Isolate Bank.
Liu H , Tang K , Pham CD , Schmerer M , Kersh EN , Raphael BH . PLoS One 2022 17 (3) e0264149 OBJECTIVES: Neisseria gonorrhoeae (gonococcus) infection is one of the most commonly reported nationally notifiable conditions in the United States. Gonococcus has developed antimicrobial resistance to each previously used antibiotic for gonorrhea therapy. However, some isolates may be still susceptible to no longer recommended, yet still effective antibiotics. This in turn suggests that targeted therapy could slow resistance development to currently recommended empirical treatments. We curated a gonococcal Ciprofloxacin Antibiotic Resistance Isolate Bank panel (Cipro-panel) as a tool for validating or developing new tests to determine ciprofloxacin susceptibility. METHOD: The Cipro-panel was selected using whole genome sequencing, bioinformatic tools, and antimicrobial susceptibility testing (AST) data. Isolates were further selected based on nucleotide variations in gyrA and parC genes. RESULTS: We selected 14 unique N. gonorrhoeae isolates from the 2006-2012 Gonococcal Isolate Surveillance Project (GISP) collection. They represented a wide range of antimicrobial susceptibility to ciprofloxacin and commonly observed nucleotide variations of gyrA and parC genes. This Cipro-panel consists of 5 isolates with resistant phenotypes (MIC > = 1 g/mL), 8 isolates with susceptible phenotypes (MIC < = 0.06 g/mL), and 1 isolate falling in the Clinical and Laboratory Standards Institute defined intermediate range. Among the gyrA variations we observed a total of 18 SNPs. Four positions had nonsynonymous changes (nucleotide positions 272, 284, 1093, and 1783). The first two positions (272 and 284) have been linked previously with resistance to ciprofloxacin (i.e. amino acid positions 91 and 95). For the parC gene, we observed a total of 21 possible SNPs. Eight of those SNPs resulted in non-synonymous amino acid changes. One location (amino acid 87) has been previously reported to be associated with ciprofloxacin resistance. CONCLUSIONS: This Cipro-Panel is useful for researchers interested in developing clinical tests related to ciprofloxacin. It could also provide additional choices for validation, quality assurance purposes and improve antibiotic usage. |
Enhancing Gonococcal Antimicrobial Resistance Surveillance in Cisgender Women, Strengthening the US Response to Resistant Gonorrhea, 2018 to 2019
Wendel KA , Mauk K , Amsterdam L , McNeil CJ , Pfister JR , Mobley V , Mettenbrink C , Nishiyama M , Terrell E , Baldwin T , Pham CD , Nash EE , Kirkcaldy RD , Schlanger K . Sex Transm Dis 2021 48 S104-s110 BACKGROUND: Cisgender women have been underrepresented in antibiotic-resistant gonorrhea (ARGC) surveillance systems. Three of 8 project sites (City of Milwaukee [MIL], Guilford County [GRB], Denver County [DEN]), funded under the Centers for Disease Control and Prevention's Strengthening the US Response to Resistant Gonorrhea (SURRG), focused efforts to better include cisgender women in ARGC surveillance. METHODS: MIL, GRB, and DEN partnered with diverse health care settings and developed gonorrhea culture criteria to facilitate urogenital specimen collection in cisgender women and men. Regional laboratories within the Antibiotic Resistance Laboratory Network performed agar dilution antibiotic susceptibility testing (AST) of gonococcal isolates. Data from 2018 and 2019 were analyzed. RESULTS: In SURRG, 90.5% (11,464 of 12,667) of the cisgender women from whom urogenital culture specimens were collected were from MIL, GRB, and DEN. Of women in SURRG whose gonococcal isolates underwent AST, 70% were from these 3 sites. In these 3 sites, a substantial proportion of cisgender women with positive urogenital cultures and AST were from health care settings other than sexually transmitted disease (STD) clinics (non-STD clinics; MIL, 56.0%; GRB, 80.4%; and DEN, 23.5%). Isolates with AST were obtained from 5.1%, 10.2%, and 2.4% of all diagnosed gonorrhea cases among cisgender women in MIL, GRB, and DEN, respectively, and were more often susceptible to all antibiotics than those from cisgender men from each of these sites. CONCLUSIONS: With focused efforts and partnerships with non-STD clinics, 3 SURRG sites were able to include robust ARGC surveillance from cisgender women. These findings may guide further efforts to improve gender equity in ARGC surveillance. |
Antimicrobial susceptibility of urogenital and extragenital neisseria gonorrhoeae isolates among men who have sex with men - SURRG and eGISP, 2018-2019
Quilter LAS , St Cyr SB , Hong J , Asbel L , Bautista I , Carter B , Casimir Y , Denny M , Ervin M , Gomez R , Harvey A , Holderman JL , Johnson K , Kohn RP , Learner ER , Mauk K , Menza T , Mettenbrink C , Nettleton WD , Nicosia KR , Pham CD , Ried C , Schlanger K , Schneider A , Soge OO , Tabidze I , Taylor SN , Tilghman W , Toler C , Weinstock H , Torrone EA . Sex Transm Dis 2021 48 S111-S117 BACKGROUND: We investigated differences in gonococcal antimicrobial susceptibility by anatomic site among cisgender men who have sex with men (MSM) using specimens collected through CDC's enhanced Gonococcal Isolate Surveillance Project (eGISP) and Strengthening the U.S. Response to Resistant Gonorrhea (SURRG). METHODS: During January 1, 2018-December 31, 2019, 12 eGISP and 8 SURRG sites collected urogenital, pharyngeal, and rectal isolates from cisgender MSM in STD clinics. Gonococcal isolates were sent to regional laboratories for antimicrobial susceptibility testing by agar dilution. To account for correlated observations, linear mixed-effects models were used to calculate geometric mean minimum inhibitory concentrations (MICs) and mixed-effects logistic regression models were used to calculate the proportion of isolates with elevated or resistant MICs; comparisons were made across anatomic sites. RESULTS: Participating clinics collected 3,974 urethral, 1,553 rectal, and 1,049 pharyngeal isolates from 5,456 unique cisgender MSM. There were no significant differences in the geometric mean MICs for azithromycin, ciprofloxacin, penicillin, and tetracycline by anatomic site. For cefixime and ceftriaxone, geometric mean MICs for pharyngeal isolates were higher compared to anogenital isolates (p < 0.05). The proportion of isolates with elevated ceftriaxone MICs (≥0.125 μg/ml) at the pharynx (0.67%) was higher than at rectal (0.13%) and urethral (0.18%) sites (p < 0.05). CONCLUSIONS: Based on data collected from multi-jurisdictional sentinel surveillance projects, antimicrobial susceptibility patterns of N. gonorrhoeae isolates may differ among MSM at extragenital sites, particularly at the pharynx. Continued investigation into gonococcal susceptibility patterns by anatomic site may be an important strategy to monitor and detect the emergence of antimicrobial resistant gonorrhea over time. |
Strengthening the U.S. Response to Resistant Gonorrhea (SURRG): An overview of a multi-site program to enhance local response capacity for antibiotic-resistant Neisseria gonorrhoeae
Schlanger K , Learner ER , Pham CD , Mauk K , Golden M , Wendel KA , Amsterdam L , McNeil CJ , Johnson K , Nguyen TQ , Holderman JL , Hasty GL , St Cyr SB , Town K , Nash EE , Kirkcaldy RD . Sex Transm Dis 2021 48 S97-S103 BACKGROUND: In 2016, CDC initiated Strengthening the U.S. Response to Resistant Gonorrhea (SURRG) in multiple jurisdictions to enhance antibiotic resistant gonorrhea rapid detection and response infrastructure and evaluate the impact of key strategies. METHODS: Eight jurisdictions were funded to establish or enhance local gonococcal culture specimen collection in STD and community clinics, conduct rapid antimicrobial susceptibility testing (AST) in local laboratories, modify systems for enhanced data collection and rapid communication of results, and initiate enhanced partner services among patients with gonorrhea demonstrating elevated minimum inhibitory concentrations (MICs) to ceftriaxone, cefixime or azithromycin. RESULTS: Grantees incorporated genital, pharyngeal, and rectal gonococcal culture collection from all genders at participating clinics. During 2018-2019, grantees collected 58,441 culture specimens from 46,822 patients and performed AST on 10,814 isolates (representing 6.8% (3,412) and 8.9% (4,883) of local reported cases in 2018 and 2019 respectively). Of isolates that underwent AST, 11% demonstrated elevated azithromycin MICs; fewer than 0.5% demonstrated elevated ceftriaxone or cefixime MICs. Among patients whose infections demonstrated elevated MICs, 81.7% were interviewed for partner elicitation; however, limited new cases were identified among partners and contacts. CONCLUSIONS: As a public health model to build capacity to slow the spread of emerging resistance, SURRG successfully expanded culture collection, implemented rapid AST, and implemented an enhanced partner services investigation approach in participating jurisdictions. Findings from SURRG may enhance preparedness efforts and inform a longer-term, comprehensive, and evidence-based public health response to emerging gonococcal resistance. Continued development of innovative approaches to address emerging resistance is needed. |
Demographic and epidemiological characteristics associated with reduced antimicrobial susceptibility to Neisseria gonorrhoeae in the United States, Strengthening the U.S. Response to Resistant Gonorrhea (SURRG), 2018-2019
Gieseker K , Learner ER , Mauk K , Barbee LA , McNeil CJ , Hasty GL , Black JM , Johnson K , Quyen Nguyen T , Shrestha D , Pham CD , St Cyr S , Schlanger K , Kirkcaldy RD . Sex Transm Dis 2021 48 S118-S123 BACKGROUND: Jurisdictions participating in Strengthening the United States Response to Resistant Gonorrhea (SURRG) implemented specimen collection for culture and antimicrobial susceptibility testing (AST) from a sample of persons of all genders (at multiple anatomic sites) attending STD clinics and community clinics. We describe the percentage and characteristics of patients whose isolates demonstrated reduced susceptibility (RS) to azithromycin, ceftriaxone, or cefixime. METHODS: We included patients from clinics that participated in SURRG whose isolates underwent AST by Etest. We defined RS as azithromycin minimum inhibitory concentrations (MICs) ≥2 μg/ml (AZM-RS), ceftriaxone MICs ≥0.125 μg/ml (CRO-RS), or cefixime MICs ≥0.25 μg/ml (CFX-RS). Patients with repeated infections appeared >1 time in the data. We calculated the frequency and percentage of patients with an isolate demonstrating RS by epidemiological characteristics. RESULTS: During 2018-2019, 10,013 patients from eight jurisdictions provided 10,735 isolates. Among 10,013 patients, 11.0% (n = 1,099) had ≥1 isolate with AZM-RS (range by jurisdiction 2.5%-18.0%). Approximately 11.3% of 8,771 of patients visiting STD clinics and approximately 8.8% of 1,242 patients visiting community clinics had an AZM-RS isolate. Nearly 6% of 1,013 females had an AZM-RS isolate; among males, the percent of patients with an AZM-RS isolate was 17.7% among 4,177 men who have sex only with men and 6.1% among 3,581 men who have sex only with women. Few (0.4%) patients had isolates with CFX-RS (n = 40) or CRO-RS (n = 43). CONCLUSIONS: Although infections with reduced cephalosporin susceptibility were rare, AZM-RS infections were prevalent in this sample of patients in multiple jurisdictions and across gender and gender of sex partner categories. |
Impact of anatomic site, specimen collection timing, and patient symptom status on Neisseria gonorrhoeae culture recovery
Nash EE , Pham CD , Raphael B , Learner ER , Mauk K , Weiner J , Mettenbrink C , Thibault CS , Fukuda A , Dobre-Buonya O , Black JM , Johnson K , Sellers K , Schlanger K . Sex Transm Dis 2021 48 S151-S156 BACKGROUND: Neisseria gonorrhoeae culture is required for antimicrobial susceptibility testing (AST), but recovering isolates from clinical specimens is challenging. While many variables influence culture recovery, studies evaluating the impact of culture specimen collection timing and patient symptom status are limited. This study analyzed urogenital and extragenital culture recovery data from CDC's Strengthening US Response to Resistant Gonorrhea (SURRG) program, a multi-site project, which enhances local N. gonorrhoeae culture and AST capacity. METHODS: Eight SURRG jurisdictions collected gonococcal cultures from patients with N. gonorrhoeae-positive nucleic acid amplification tests (NAATs) attending STD and community clinics. Matched NAAT and culture specimens from the same anatomic site were collected, and culture recovery was assessed. Time between NAAT and culture specimen collection was categorized as, same day, 1-7 days, 8-14 days, or ≥ 15 days and patient symptoms were matched to the anatomic site where culture specimens were collected. RESULTS: From 2018-2019, among persons with N. gonorrhoeae-positive NAAT, urethral infections resulted in the highest culture recovery (5927/6515 = 91.0%), followed by endocervical, (222/363 = 61.2%), vaginal (63/133 = 47.4%) rectal (1117/2805 = 39.8%), and pharyngeal (1019/3678 = 27.7%) infections. Culture recovery was highest when specimens were collected on the same day as NAAT specimens and significantly decreased after 7 days. Symptoms were significantly associated with culture recovery at urethral (p = <0.0001) and rectal (p = <0.0001) sites of infection but not endocervical, vaginal, or pharyngeal sites. CONCLUSIONS: Culture specimen collection timing and patient symptomatic status can impact culture recovery. These findings can guide decisions about culture collection protocols to maximize culture recovery and strengthen detection of antimicrobial resistant infections. |
Implementation and evaluation of gradient strip antimicrobial susceptibility testing in US public health laboratories to respond to resistant gonorrhea
Raphael BH , Pham CD , Sharpe S , Mauk K , Harvey A , Khubbar M , Triplett L , Soge OO , Denny M , Palavecino EL , Finney R , Olsen A , Carlson J , St Cyr SB , Schlanger K , Kersh EN . Sex Transm Dis 2021 48 S157-S160 BACKGROUND: Gradient strip antimicrobial susceptibility testing (AST) using Etest® is conducted by local public health jurisdictions participating in the Strengthening the U.S. Response to Resistant Gonorrhea (SURRG) program to inform public health responses to resistant gonorrhea. Proficiency testing results across the participating laboratories were analyzed and a comparison of Etest® with the agar dilution method was conducted. METHODS: Laboratories participating in SURRG performed Etest® for azithromycin (AZM), cefixime (CFX), and ceftriaxone (CRO). Concurrence between minimum inhibitory concentrations (MICs) obtained with Etest® versus the agar dilution method using corresponding isolates was defined as +/- 1 double dilution. Specific levels of reduced susceptibility were termed "alerts" and included isolates with the following MICs: ≥ 2.0 μg/ml (AZM), ≥ 0.25 μg/ml (CFX), and ≥ 0.125 μg/ml (CRO). Categorical (alert/non-alert) agreement was calculated for MICs determined using Etest® and agar dilution methods. RESULTS: SURRG laboratories had high proficiency testing scores (≥98%) and low levels of inter-laboratory variations in MICs. The overall concurrence of MICs (essential agreement) determined using agar dilution and Etest® was 96% (CRO), 96% (CFX), and 95% (AZM). Depending on the antibiotic tested, between 27-66% of isolates with alert MICs determined by Etest® also had alert MICs using the reference agar dilution methodology, however most of these alert MICs were detected at threshold levels. CONCLUSIONS: This study demonstrates that MICs produced by SURRG laboratories using Etest® have a high level of concurrence with agar dilution. Although confirmation of specific alert MICs varied, Etest® facilities rapid detection and response to emerging resistant gonorrhea. |
Enhancing U.S. local, state, and federal preparedness through simulated interactive tabletop exercises of a mock antibiotic-resistant gonorrhea outbreak, 2018-2019
Schlanger K , Black JM , Smith M , Ridpath A , Crause C , Holderman JL , Henderson K , Hardrick H , Pham CD , Howard G , Kirkcaldy RD . Sex Transm Dis 2021 48 S174-S179 BACKGROUND: Responding effectively to outbreaks of antibiotic-resistant gonorrhea (ARGC) in the future will likely prove challenging. Tabletop exercises (TTXs) may assist local, state, and federal public health officials evaluate existing ARGC outbreak response plans, strengthen preparedness and response effectiveness, and identify critical gaps to address prior to an outbreak. METHODS: In 2018-2019, CDC collaborated with state partners to develop and implement TTXs to simulate a public health emergency involving an ARGC outbreak. Prior to the TTXs, two state-local health department pairs developed ARGC outbreak response plans. During each one-day exercise (in Indiana and Illinois), participants discussed roles, clinical management, public health response, and communication based on pre-developed response plans. Observers identified outbreak response strengths and gaps, and participants completed feedback forms. RESULTS: Forty-one (Illinois) and 48 people (Indiana) participated in each TTX, including: STD clinical staff, laboratorians, public health infectious disease program staff, and CDC observers. Strengths and gaps varied by jurisdiction, but identified gaps included: (1) local access to gonorrhea culture and timely antimicrobial susceptibility testing (AST), (2) protocols for clinical management of suspected treatment failures, (3) communication plans, and (4) clarity regarding state and local responsibilities. CDC observers identified opportunities to provide national-level technical assistance, foster local AST, and develop further response guidance. TTX summary reports were used to guide modifications to local response plans to address gaps. CONCLUSIONS: The TTXs allowed participants to practice responding to a simulated public health emergency and may have enhanced local response capacity. CDC made TTX implementation materials publicly available. |
Outcomes of traditional and enhanced gonorrhea partner services in the strengthening the US Response to Resistant Gonorrhea Project, 2017- 2019
Learner ER , Schlanger K , Mauk K , Pham CD , Holderman JL , Kirkcaldy RD . Sex Transm Dis 2021 48 S124-S130 INTRODUCTION: The CDC implemented Strengthening the U.S. Response to Resistant Gonorrhea (SURRG) to build local detection and response capacity and evaluate responses to antibiotic-resistant gonorrhea outbreaks, including partner services for gonorrhea. We evaluated outcomes of traditional partner services conducted under SURRG, which involved (1) counseling index patients and eliciting sexual partners, (2) interviewing, testing and treating partners, and (3) providing partner services to partners newly diagnosed with gonorrhea. We also evaluated outcomes of enhanced partner services, which additionally involved interviewing and testing partners of persons who tested negative, and social contacts of index patients and partners. METHODS: We analyzed partner services investigation data from eight jurisdictions participating in SURRG from 2017 through 2019. We summed total index patients, partners from traditional partner services, and partners and contacts from enhanced partner services, and calculated partner services outcomes among partners and contacts. We also visualized sexual networks from partner services data. RESULTS: Of 1,242 index patients identified, 506 named at least one sexual partner. Traditional partner services yielded 1,088 sexual partners and 105 were newly diagnosed with gonorrhea. Enhanced partner services yielded an additional 59 sexual partners and 52 social contacts. Of those partners and contacts, 3 were newly diagnosed with gonorrhea. Network visualization revealed sparse networks with few complex partnership clusters. CONCLUSIONS: Traditional partner services for gonorrhea may be useful for eliciting, notifying, and diagnosing partners of index patients in an outbreak setting. Enhanced partner services are unlikely to be effective for eliciting, notifying, and diagnosing a substantial number of additional people. |
Phylogenomic analysis reveals persistence of gonococcal strains with reduced-susceptibility to extended-spectrum cephalosporins and mosaic penA-34.
Thomas 4th JC , Joseph SJ , Cartee JC , Pham CD , Schmerer MW , Schlanger K , St Cyr SB , Kersh EN , Raphael BH . Nat Commun 2021 12 (1) 3801 The recent emergence of strains of Neisseria gonorrhoeae associated with treatment failures to ceftriaxone, the foundation of current treatment options, has raised concerns over a future of untreatable gonorrhea. Current global data on gonococcal strains suggest that several lineages, predominately characterized by mosaic penA alleles, are associated with elevated minimum inhibitory concentrations (MICs) to extended spectrum cephalosporins (ESCs). Here we report on whole genome sequences of 813 N. gonorrhoeae isolates collected through the Gonococcal Isolate Surveillance Project in the United States. Phylogenomic analysis revealed that one persisting lineage (Clade A, multi-locus sequence type [MLST] ST1901) with mosaic penA-34 alleles, contained the majority of isolates with elevated MICs to ESCs. We provide evidence that an ancestor to the globally circulating MLST ST1901 clones potentially emerged around the early to mid-20th century (1944, credibility intervals [CI]: 1935-1953), predating the introduction of cephalosporins, but coinciding with the use of penicillin. Such results indicate that drugs with novel mechanisms of action are needed as these strains continue to persist and disseminate globally. |
Genomic analysis of the predominant strains and antimicrobial resistance determinants within 1479 Neisseria gonorrhoeae isolates from the U.S. Gonococcal Isolate Surveillance Project in 2018.
Reimche JL , Chivukula VL , Schmerer MW , Joseph SJ , Pham CD , Schlanger K , St Cyr SB , Weinstock HS , Raphael BH , Kersh EN , Gernert KM . Sex Transm Dis 2021 48 S78-S87 BACKGROUND: The prevalence of Neisseria gonorrhoeae (GC) isolates with elevated minimum inhibitory concentrations (MICs) to various antibiotics continues to rise in the U.S. and globally. Genomic analysis provides a powerful tool for surveillance of circulating strains, antimicrobial resistance determinants, and understanding of transmission through a population. METHODS: GC isolates collected from the U.S. Gonococcal Isolate Surveillance Project (GISP) in 2018 (n=1479) were sequenced and characterized. Whole genome sequencing was used to identify sequence types, antimicrobial resistance profiles, and phylogenetic relationships across demographic and geographic populations. RESULTS: Genetic characterization identified that (1) 80% of the GC isolates were represented in 33 multilocus sequence types, (2) isolates clustered in 23 major phylogenetic clusters with select phenotypic and demographic prevalence, and (3) common antimicrobial resistance determinants associated with low-level or high-level decreased susceptibility or resistance to relevant antibiotics. CONCLUSIONS: Characterization of this 2018 GISP genomic dataset, which is the largest U.S. whole genome sequence data set to date, sets the basis for future prospective studies, and establishes a genomic baseline of GC populations for local and national monitoring. |
Sustained Transmission of Neisseria gonorrhoeae with High-Level Resistance to Azithromycin, Indianapolis, Indiana 2017-2018.
Holderman JL , Thomas JC , Schlanger K , Black JM , Town K , Cyr SB , Pham CD , Kirkcaldy RD . Clin Infect Dis 2021 73 (5) 808-815 BACKGROUND: Since 2014, Neisseria gonorrhoeae (Ng) azithromycin (AZM) susceptibility has declined in the United States, but high-level azithromycin resistance (HL-AZMR) has been infrequent and sporadic. We describe a cluster of 14 Ng isolates with HL-AZMR identified in Indianapolis over 13 months. METHODS: Ng culture specimens (genital and extragenital) were collected from attendees of the Bell Flower Clinic. Isolates underwent antimicrobial susceptibility testing (AST) by Etest . AZM minimum inhibitory concentrations 256 g/ml were classified as HL-AZMR. Local disease intervention specialists interviewed patients whose isolates demonstrated HL-AZMR and conducted partner services. Relatedness of isolates was investigated by genomic analyses. RESULTS: During 2017-2018, 1,016 Ng isolates collected at the Bell Flower Clinic underwent AST. Fourteen isolates (1.4%) from 12 men collected over 13 months demonstrated HL-AZMR; all were cephalosporin-susceptible. Of the 12 men, nine were white and reported male sex partners. Nine of the men were able to be re-tested; all were cured with 250mg ceftriaxone plus 1g azithromycin. Two men named each other as partners; no other partners in common were reported. Genomic analysis demonstrated close relatedness of the HL-AZMR isolates and a novel combination of a mosaic-mtrR promoter along with 23S rRNA mutations that appear to have emerged from circulating strains. CONCLUSIONS: The close genetic relatedness with limited epidemiological linkages between patients highlights the challenges of gonorrhea partner investigations and suggests undetected local transmission. Local AST, rapid public health action, and epidemiologic investigations combined with genomic analysis provides a multi-pronged approach to understanding an STD outbreak. |
Sustained Transmission of Neisseria gonorrhoeae with High-Level Resistance to Azithromycin, in Indianapolis, Indiana, 2017-2018.
Holderman JL , Thomas JC , Schlanger K , Black JM , Town K , Cyr SB , Pham CD , Kirkcaldy RD . Clin Infect Dis 2021 73 (5) 808-815 BACKGROUND: Since 2014, Neisseria gonorrhoeae (Ng) azithromycin (AZM) susceptibility has declined in the United States, but high-level azithromycin resistance (HL-AZMR) has been infrequent and sporadic. We describe a cluster of 14 Ng isolates with HL-AZMR identified in Indianapolis over 13 months. METHODS: Ng culture specimens (genital and extragenital) were collected from attendees of the Bell Flower Clinic. Isolates underwent antimicrobial susceptibility testing (AST) by Etest ®. AZM minimum inhibitory concentrations ≥256 µg/ml were classified as HL-AZMR. Local disease intervention specialists interviewed patients whose isolates demonstrated HL-AZMR and conducted partner services. Relatedness of isolates was investigated by genomic analyses. RESULTS: During 2017-2018, 1,016 Ng isolates collected at the Bell Flower Clinic underwent AST. Fourteen isolates (1.4%) from 12 men collected over 13 months demonstrated HL-AZMR; all were cephalosporin-susceptible. Of the 12 men, nine were white and reported male sex partners. Nine of the men were able to be re-tested; all were cured with 250 mg ceftriaxone plus 1g azithromycin. Two men named each other as partners; no other partners in common were reported. Genomic analysis demonstrated close relatedness of the HL-AZMR isolates and a novel combination of a mosaic-mtrR promoter along with 23S rRNA mutations that appear to have emerged from circulating strains. CONCLUSIONS: The close genetic relatedness with limited epidemiological linkages between patients highlights the challenges of gonorrhea partner investigations and suggests undetected local transmission. Local AST, rapid public health action, and epidemiologic investigations combined with genomic analysis provides a multi-pronged approach to understanding an STD outbreak. |
Notes from the field: First case in the United States of Neisseria gonorrhoeae harboring emerging mosaic penA60 allele, conferring reduced susceptibility to cefixime and ceftriaxone
Picker MA , Knoblock RJ , Hansen H , Bautista I , Griego R , Barber L , Bendik W , Lam K , Adelman E , Qiu-Shultz Z , Raphael BH , Pham CD , Kersh EN , Weinstock H , St Cyr SB . MMWR Morb Mortal Wkly Rep 2020 69 (49) 1876-1877 In November 2019, the Southern Nevada Public Health Laboratory of the Southern Nevada Health District (SNHD) identified a male urethral gonococcal isolate later demonstrating reduced susceptibility to cefixime (minimum inhibitory concentration [MIC] = 2.0 μg/mL) and ceftriaxone (MIC = 1.0 μg/mL) but susceptible to azithromycin (MIC = 0.25 μg/mL). Molecular testing by CDC in the United States revealed the emerging mosaic penA60 allele, first identified in Japan in 2016 (1), which confers reduced susceptibility to cephalosporins and increases the risk for treatment failure. The penA60 allele has been identified in China (2), Canada (3,4), Denmark (5), Australia (6), France (7), and the United Kingdom (8). The Nevada case is the first identified case of a Neisseria gonorrhoeae isolate harboring the mosaic penA60 allele reported in the United States. |
Atypical Mutation in Neisseria gonorrhoeae 23S rRNA Associated with High-Level Azithromycin Resistance.
Pham CD , Nash E , Liu H , Schmerer MW , Sharpe S , Woods G , Roland B , Schlanger K , St Cyr SB , Carlson J , Sellers K , Olsen A , Sanon R , Hardin H , Soge OO , Raphael BH , Kersh EN . Antimicrob Agents Chemother 2020 65 (2) A2059G mutation in the 23S rRNA gene is the only reported mechanism conferring high-level azithromycin resistance (HL-AZMR) in Neisseria gonorrhoea Through U.S. gonococcal antimicrobial resistance surveillance projects, we identified four HL-AZMR gonococcal isolates lacking this mutational genotype. Genetic analysis revealed an A2058G mutation of 23S rRNA alleles in all four isolates. In vitro selected gonococcal strains with homozygous A2058G recapitulated the HL-AZMR phenotype. Taken together, we postulate that A2058G mutation confers HL-AZMR in N. gonorrhoeae. |
Azithromycin susceptibility of Neisseria gonorrhoeae in the USA in 2017: a genomic analysis of surveillance data.
Gernert KM , Seby S , Schmerer MW , Thomas JCth , Pham CD , Cyr SS , Schlanger K , Weinstock H , Shafer WM , Raphael BH , Kersh EN . Lancet Microbe 2020 1 (4) e154-e164 BACKGROUND: The number of cases of gonorrhoea in the USA and worldwide caused by Neisseria gonorrhoeae is increasing (555 608 reported US cases in 2017, and 87 million cases worldwide in 2016). Many countries report declining in vitro susceptibility of azithromycin, which is a concern because azithromycin and ceftriaxone are the recommended dual treatment in many countries. We aimed to identify strain types associated with decreased susceptibility to azithromycin. METHODS: We did a genomic analysis of N gonorrhoeae isolates obtained by the US Gonococcal Isolate Surveillance Project. Isolates were whole-genome sequenced based on decreased susceptibility to azithromycin (minimal inhibitory concentration [MIC] ≥2 μg/mL, using agar dilution antibiotic susceptibility testing) and geographical representation. Bioinformatic analyses established genomic diversity, strain population dynamics, and antimicrobial resistance profiles. FINDINGS: 410 isolates were sorted into more than 20 unique phylogenetic clades. One predominant persistent clade (consisting of 97 isolates) included the most isolates with azithromycin MICs of 2 μg/mL or higher (61 of 97 [63%] vs 59 of 311 [19%]; p<0·0001) and carried a mosaic mtr (multiple transferable resistance) locus (68 of 97 [70%] vs two of 313 [1%]; p<0·0001). Of the remaining 313 isolates, 57 (18%) had decreased susceptibility to azithromycin (MIC ≥4 μg/mL), which was attributed to 23S rRNA variants (56 of 57 [98%]) and formed phylogenetically diverse clades, showing various levels of clonal expansion. INTERPRETATION: Reduced azithromycin susceptibility was associated with expanding and persistent clades harbouring two well described resistance mechanisms, mosaic mtr locus and 23S rRNA variants. Understanding the role of recombination, particularly within the mtr locus, on the fitness and expansion of strains with decreased susceptibility has important implications for the public health response to minimise gonorrhoea transmission. FUNDING: US Centers for Disease Control and Prevention (CDC), CDC Combating Antibiotic Resistant Bacteria initiative, Oak Ridge Institute for Science Education, US Department of Energy/CDC/Emory University, National Institutes of Health, and Biomedical Laboratory Research and Development Service of the US Department of Veterans Affairs. |
Utility of MALDI-TOF MS for differentiation of Neisseria gonorrhoeae isolates with dissimilar azithromycin susceptibility profiles
Pham CD , Pettus K , Nash EE , Liu H , St Cyr SB , Schlanger K , Papp J , Gartin J , Dorji T , Akullo K , Kersh EN . J Antimicrob Chemother 2020 75 (11) 3202-3208 BACKGROUND: Antibiotic-resistant gonorrhoea has been a chronic public health burden since the mid-1930s. Recent emergence of isolates resistant to the current recommended antibiotics for gonorrhoea further magnifies the threat of untreatable gonorrhoea. The lack of new, effective antibiotics highlights the need for better understanding of the population structure of Neisseria gonorrhoeae in order to provide greater insight on how to curtail the spread of antimicrobial-resistant N. gonorrhoeae. OBJECTIVES: To explore a potential application of MALDI-TOF MS to differentiate N. gonorrhoeae displaying different levels of susceptibility to the antibiotic azithromycin. METHODS: We conducted MALDI-TOF MS using the Bruker Biotyper on 392 N. gonorrhoeae isolates collected through the Gonococcal Isolate Surveillance Project (GISP) and/or the Strengthening the United States Response to Resistant Gonorrhea (SURRG) project. The MALDI-TOF MS spectra were visually analysed to assess the presence of distinctive peak(s). Statistical analysis was performed to assess the relationship between gonococcal isolates with the distinct protein peak and antibiotic susceptibility. RESULTS: In this study, we were able to differentiate N. gonorrhoeae isolates into two distinct subpopulations using MALDI-TOF MS. Isolates were distinguished by the presence or absence of a spectral peak at 11 300 Da. Notably, these two groups exhibited different levels of susceptibility to azithromycin. CONCLUSIONS: We have shown that in addition to its ability to identify N. gonorrhoeae, MALDI-TOF MS could also be used to differentiate gonococcal isolates with different levels of susceptibility to azithromycin. |
Genomic characterization of Neisseria gonorrhoeae Strains from 2016 United States Sentinel Surveillance Displaying Reduced Susceptibility to Azithromycin.
Schmerer MW , Abrams AJ , Seby S , Thomas JC4th , Cartee J , Lucking S , Vidyaprakash E , Pham CD , Sharpe S , Pettus K , St Cyr SB , Torrone EA , Kersh EN , Gernert KM . Antimicrob Agents Chemother 2020 64 (5) In 2016, the proportion of Neisseria gonorrhoeae isolates with reduced susceptibility to azithromycin rose to 3.6%. A phylogenetic analysis of 334 N. gonorrhoeae isolates collected in 2016 revealed a single, geographically diverse lineage of isolates with MICs of 2-16 mug/mL that carried a mosaic-like mtr locus, whereas the majority of isolates with MICs >/= 16 mug/mL appeared sporadically and carried 23S rRNA mutations. Continued molecular surveillance of N. gonorrheae will identify new resistance mechanisms. |
Expanding US Laboratory Capacity for Neisseria gonorrhoeae Antimicrobial Susceptibility Testing and Whole Genome Sequencing through CDC's Antibiotic Resistance Laboratory Network.
Kersh EN , Pham CD , Papp JR , Myers R , Steece R , Kubin G , Gautom R , Nash EE , Sharpe S , Gernert KM , Schmerer M , Raphael BH , Henning T , Gaynor AM , Soge O , Schlanger K , Kirkcaldy RD , St Cyr SB , Torrone EA , Bernstein K , Weinstock H . J Clin Microbiol 2020 58 (4) US gonorrhea rates are rising, and antibiotic-resistant Neisseria gonorrhoeae (AR-Ng) is an urgent public health threat. Since implementation of nucleic acid amplification tests for Ng identification, capacity for culturing Ng in the US has declined, along with the ability to perform culture-based antimicrobial susceptibility testing (AST). Yet, AST is critical for detecting and monitoring AR-Ng. In 2016, CDC established the Antibiotic Resistance Laboratory Network (AR Lab Network) to shore up national capacity for detecting several resistance threats including Ng. AR-Ng testing, a sub-activity of CDC's AR Lab Network, is performed in a tiered network of approximately 35 local laboratories, four regional laboratories (state public health laboratories in MD, TN, TX, WA), and CDC's national reference laboratory. Local laboratories receive specimens from approximately 60 clinics associated with the Gonococcal Isolate Surveillance Project (GISP), enhanced GISP (eGISP), and Strengthening the U.S. Response to Resistant Gonorrhea (SURRG). They isolate and ship up to 20,000 isolates to regional laboratories for culture-based agar dilution AST with seven antibiotics and for whole genome sequencing of up to 5,000 isolates. The CDC further examines concerning isolates and monitors genetic AR markers. During 2017 and 2018, the network tested 8,214 and 8,628 Ng isolates, and CDC received 531 and 646 concerning isolates, and 605 and 3,159 sequences, respectively. In summary, the AR Lab Network supported laboratory capacity for Ng-AST and associated genetic marker detection, expanding pre-existing notification and analysis systems for resistance detection. Continued, robust AST and genomic capacity can help inform national public health monitoring and intervention. |
Emergence of Neisseria gonorrhoeae Strains Harboring a Novel Combination of Azithromycin-Attenuating Mutations.
Pham CD , Sharpe S , Schlanger K , St Cyr S , Holderman J , Steece R , Soge OO , Masinde G , Arno J , Schmerer M , Kersh EN . Antimicrob Agents Chemother 2019 63 (4) The nimbleness of Neisseria gonorrhoeae to evade the effect of antibiotics has perpetuated the fight against antibiotic-resistant gonorrhea for more than 80 years. The ability to develop resistance to antibiotics is attributable to its indiscriminate nature in accepting and integrating exogenous DNA into its genome. Here, we provide data demonstrating a novel combination of the 23S rRNA A2059G mutation with a mosaic-multiple transferable resistance (mosaic-mtr) locus haplotype in 14 N. gonorrhoeae isolates with high-level azithromycin MICs (>/=256 mug/ml), a combination that may confer more fitness than in previously identified isolates with high-level azithromycin resistance. To our knowledge, this is the first description of N. gonorrhoeae strains harboring this novel combination of resistance determinants. These strains were isolated at two independent jurisdictions participating in the Gonococcal Isolate Surveillance Project (GISP) and in the Strengthening the U.S. Response to Resistant Gonorrhea (SURRG) project. The data suggest that the genome of N. gonorrhoeae continues to shuffle its genetic material. These findings further illuminate the genomic plasticity of N. gonorrhoeae, which allows this pathogen to develop mutations to escape the inhibitory effects of antibiotics. |
Evidence of Recent Genomic Evolution in Gonococcal Strains with Decreased Susceptibility to Cephalosporins or Azithromycin in the United States, 2014-2016.
Thomas JC , Seby S , Abrams AJ , Cartee J , Lucking S , Vidyaprakash E , Schmerer M , Pham CD , Hong J , Torrone E , St Cyr S , Shafer WM , Bernstein K , Kersh EN , Gernert KM . J Infect Dis 2019 220 (2) 294-305 BACKGROUND: Given the lack of new antimicrobials or a vaccine, understanding the evolutionary dynamics of Neisseria gonorrhoeae is a significant public and global health priority. We investigated the emergence and spread of gonococcal strains with decreased susceptibility to cephalosporins and azithromycin using detailed genomic analyses of gonococcal isolates collected in the United States from 2014 to 2016. METHODS: We sequenced the genomes of 649 isolates collected through the Gonococcal Isolate Surveillance Project (GISP). We examined the genetic relatedness of isolates and assessed associations between clades and various genotypic and phenotypic combinations. RESULTS: We identified a large and clonal lineage of strains (MLST ST9363) associated with elevated azithromycin MICs (AZI em), characterized by a mosaic mtr locus (C-substitution in the mtrR promoter, mosaic mtrR and mtrD). Mutations in 23S rRNA were sporadically distributed among AZI em strains. Another clonal group (MLST ST1901) possessed seven unique PBP2 patterns, and it shared common mutations in other genes associated with cephalosporin resistance. CONCLUSIONS: Whole genome sequencing methods can enhance monitoring of antimicrobial resistant gonococcal strains by identifying gonococcal populations containing mutations of concern. These methods could inform the development of point-of-care diagnostic tests designed to determine the specific antibiotic susceptibility profile of a gonococcal infection within a patient. |
In vitro activity of EDTA and TOL-463 against Neisseria gonorrhoeae
Nash EE , Henning TC , Pham CD , Pettus K , Sharpe S , Kersh EN . Diagn Microbiol Infect Dis 2018 93 (4) 369-371 Neisseria gonorrhoeae quickly develops drug resistance. Time-kill curves revealed that EDTA and TOL-463 inhibit growth similar to penicillin, ciprofloxacin, and azithromycin. Furthermore, synergistic and additive antimicrobial interactions occurred when EDTA and TOL-463 were combined with penicillin or azithromycin, respectively, suggesting that further investigations into these unconventional antimicrobials may be advantageous. |
Mechanistic Basis for Decreased Antimicrobial Susceptibility in a Clinical Isolate of Neisseria gonorrhoeae Possessing a Mosaic-Like mtr Efflux Pump Locus.
Rouquette-Loughlin CE , Reimche JL , Balthazar JT , Dhulipala V , Gernert KM , Kersh EN , Pham CD , Pettus K , Abrams AJ , Trees DL , St Cyr S , Shafer WM . mBio 2018 9 (6) Recent reports suggest that mosaic-like sequences within the mtr (multiple transferable resistance) efflux pump locus of Neisseria gonorrhoeae, likely originating from commensal Neisseria sp. by transformation, can increase the ability of gonococci to resist structurally diverse antimicrobials. Thus, acquisition of numerous nucleotide changes within the mtrR gene encoding the transcriptional repressor (MtrR) of the mtrCDE efflux pump-encoding operon or overlapping promoter region for both along with those that cause amino acid changes in the MtrD transporter protein were recently reported to decrease gonococcal susceptibility to numerous antimicrobials, including azithromycin (Azi) (C. B. Wadsworth, B. J. Arnold, M. R. A. Satar, and Y. H. Grad, mBio 9:e01419-18, 2018, https://doi.org/10.1128/mBio.01419-18). We performed detailed genetic and molecular studies to define the mechanistic basis for why such strains can exhibit decreased susceptibility to MtrCDE antimicrobial substrates, including Azi. We report that a strong cis-acting transcriptional impact of a single nucleotide change within the -35 hexamer of the mtrCDE promoter as well gain-of-function amino acid changes at the C-terminal region of MtrD can mechanistically account for the decreased antimicrobial susceptibility of gonococci with a mosaic-like mtr locus.IMPORTANCE Historically, after introduction of an antibiotic for treatment of gonorrhea, strains of N. gonorrhoeae emerge that display clinical resistance due to spontaneous mutation or acquisition of resistance genes. Genetic exchange between members of the Neisseria genus occurring by transformation can cause significant changes in gonococci that impact the structure of an antibiotic target or expression of genes involved in resistance. The results presented here provide a framework for understanding how mosaic-like DNA sequences from commensal Neisseria that recombine within the gonococcal mtr efflux pump locus function to decrease bacterial susceptibility to antimicrobials, including antibiotics used in therapy of gonorrhea. |
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