Last data update: Sep 23, 2024. (Total: 47723 publications since 2009)
Records 1-16 (of 16 Records) |
Query Trace: McDougal LK [original query] |
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Improved Subtyping of Staphylococcus aureus Clonal Complex 8 Strains Based on Whole-Genome Phylogenetic Analysis.
Bowers JR , Driebe EM , Albrecht V , McDougal LK , Granade M , Roe CC , Lemmer D , Rasheed JK , Engelthaler DM , Keim P , Limbago BM . mSphere 2018 3 (3) Strains of Staphylococcus aureus in clonal complex 8 (CC8), including USA300, USA500, and the Iberian clone, are prevalent pathogens in the United States, both inside and outside health care settings. Methods for typing CC8 strains are becoming obsolete as the strains evolve and diversify, and whole-genome sequencing has shown that some strain types fall into multiple sublineages within CC8. In this study, we attempt to clarify the strain nomenclature of CC8, classifying the major strain types based on whole-genome sequence phylogenetics using both methicillin-resistant S. aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) genomes. We show that isolates of the Archaic and Iberian clones from decades ago make up the most basal clade of the main CC8 lineages and that at least one successful lineage of CC8, made up mostly of MSSA, diverged before the other well-known strain types USA500 and USA300. We also show that the USA500 type includes two clades separated by the previously described "Canadian epidemic MRSA" strain CMRSA9, that one clade containing USA500 also contains the USA300 clade, and that the USA300-0114 strain type is not a monophyletic group. Additionally, we present a rapid, simple CC8 strain-typing scheme using real-time PCR assays that target single nucleotide polymorphisms (SNPs) derived from our CC8 phylogeny and show the significant benefit of using more stable genomic markers based on evolutionary lineages over traditional S. aureus typing techniques. This more accurate and accessible S. aureus typing system may improve surveillance and better inform the epidemiology of this very important pathogen.IMPORTANCEStaphylococcus aureus is a major human pathogen worldwide in both community and health care settings. Surveillance for S. aureus strains is important to our understanding of their spread and to informing infection prevention and control. Confusion surrounding the strain nomenclature of one of the most prevalent lineages of S. aureus, clonal complex 8 (CC8), and the imprecision of current tools for typing S. aureus make surveillance and source tracing difficult and sometimes misleading. In this study, we clarify the CC8 strain designations and propose a new typing scheme for CC8 isolates that is rapid and easy to use. This typing scheme is based on relatively stable genomic markers, and we demonstrate its superiority over traditional typing techniques. This scheme has the potential to greatly improve epidemiological investigations of S. aureus. |
Staphylococcus aureus colonization and strain type at various body sites among patients with a closed abscess and uninfected controls at U.S. emergency departments
Albrecht VS , Limbago BM , Moran GJ , Krishnadasan A , Gorwitz RJ , McDougal LK , Talan DA . J Clin Microbiol 2015 53 (11) 3478-84 INTRODUCTION: Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is a prevalent cause of skin and soft tissue infections (SSTI), but the association between CA-MRSA colonization and infection remains uncertain. We studied the carriage frequency at several body sites and the diversity of S. aureus strains from patients with and without SSTI. MATERIALS AND METHODS: Case-subjects with a closed skin abscess (i.e., without drainage) and matched control subjects without a skin infection (N=147 each) presenting to 10 U.S. emergency departments were cultured at the nares, throat, rectum, and groin using broth enrichment; wounds were cultured from abscess cases. Methicillin resistance testing and spa typing were performed for all S. aureus isolates. RESULTS: S. aureus was found in 85/147 (57.8%) of abscesses; 49 were MRSA, 36 were MSSA. MRSA colonization was more common among cases (59/147; 40.1%) than controls (27/147; 18.4%) overall (p<0.001), and at each body site; no differences were observed for MSSA. S. aureus-infected subjects were usually (75/85) colonized with the infecting strain; among MRSA-infected subjects this was most common in the groin. The CC8 lineage accounted for most of both infecting and colonizing isolates, although more than 16 distinct strains were identified. Nearly all MRSA infections were inferred as USA300. There was more diversity among colonizing than infecting isolates, and among those isolated from controls versus cases. CONCLUSIONS: CC8 S. aureus is a common colonizer of persons with and without skin infections. Detection of S. aureus colonization, and especially MRSA, may be enhanced by extra-nasal site culture. |
Prevalence of and risk factors for vancomycin-resistant Staphylococcus aureus precursor organisms in southeastern Michigan
Albrecht VS , Zervos MJ , Kaye KS , Tosh PK , Arshad S , Hayakawa K , Kallen AJ , McDougal LK , Limbago BM , Guh AY . Infect Control Hosp Epidemiol 2014 35 (12) 1531-4 We assessed for vancomycin-resistant Staphylococcus aureus (VRSA) precursor organisms in southeastern Michigan, an area known to have VRSA. The prevalence was 2.5% (pSK41-positive methicillin-resistant S. aureus, 2009-2011) and 1.5% (Inc18-positive vancomycin-resistant Enterococcus, 2006-2013); Inc18 prevalence significantly decreased after 2009 (3.7% to 0.82%). Risk factors for pSK41 included intravenous vancomycin exposure. |
Transmission of methicillin-resistant Staphylococcus aureus infection through solid organ transplantation: confirmation via whole genome sequencing.
Wendt JM , Kaul D , Limbago BM , Ramesh M , Cohle S , Denison AM , Driebe EM , Rasheed JK , Zaki SR , Blau DM , Paddock CD , McDougal LK , Engelthaler DM , Keim PS , Roe CC , Akselrod H , Kuehnert MJ , Basavaraju SV . Am J Transplant 2014 14 (11) 2633-9 We describe two cases of donor-derived methicillin-resistant Staphylococcus aureus (MRSA) bacteremia that developed after transplantation of organs from a common donor who died from acute MRSA endocarditis. Both recipients developed recurrent MRSA infection despite appropriate antibiotic therapy, and required prolonged hospitalization and hospital readmission. Comparison of S. aureus whole genome sequence of DNA extracted from fixed donor tissue and recipients' isolates confirmed donor-derived transmission. Current guidelines emphasize the risk posed by donors with bacteremia from multidrug-resistant organisms. This investigation suggests that, particularly in the setting of donor endocarditis, even a standard course of prophylactic antibiotics may not be sufficient to prevent donor-derived infection. |
Report of the 13th vancomycin-resistant Staphylococcus aureus from the United States
Limbago BM , Kallen AJ , Zhu W , Eggers P , McDougal LK , Albrecht VS . J Clin Microbiol 2013 52 (3) 998-1002 Vancomycin-resistant Staphylococcus aureus (VRSA), important multidrug-resistant organisms of public health concern, have been infrequently identified in the United States since 2002. All previous VRSA belonged to clonal complex 5, a lineage associated primarily with healthcare. This report describes the most recent (13th) U.S. VRSA; the first in a community strain. |
Molecular characterization of Staphylococcus aureus and influenza virus coinfections in patients with fatal pneumonia
Denison AM , Deleon-Carnes M , Blau DM , Shattuck EC , McDougal LK , Rasheed JK , Limbago BM , Zaki SR , Paddock CD . J Clin Microbiol 2013 51 (12) 4223-5 Molecular techniques were used to characterize genetic features of Staphylococcus aureus in 66 fatal cases of pneumonia caused by S. aureus and influenza A or B viruses. Nucleic acids were extracted from formalin-fixed, paraffin-embedded tissues. The majority of cases revealed genetic markers for Panton-Valentine leukocidin, mecA, and spa type t008. |
Prevalence and risk factors associated with vancomycin-resistant Staphylococcus aureus precursor organism colonization among patients with chronic lower-extremity wounds in southeastern Michigan
Tosh PK , Agolory S , Strong BL , Verlee K , Finks J , Hayakawa K , Chopra T , Kaye KS , Gilpin N , Carpenter CF , Haque NZ , Lamarato LE , Zervos MJ , Albrecht VS , McAllister SK , Limbago B , MacCannell DR , McDougal LK , Kallen AJ , Guh AY . Infect Control Hosp Epidemiol 2013 34 (9) 954-60 BACKGROUND: Of the 13 US vancomycin-resistant Staphylococcus aureus (VRSA) cases, 8 were identified in southeastern Michigan, primarily in patients with chronic lower-extremity wounds. VRSA infections develop when the vanA gene from vancomycin-resistant enterococcus (VRE) transfers to S. aureus. Inc18-like plasmids in VRE and pSK41-like plasmids in S. aureus appear to be important precursors to this transfer. OBJECTIVE: Identify the prevalence of VRSA precursor organisms. DESIGN: Prospective cohort with embedded case-control study. PARTICIPANTS: Southeastern Michigan adults with chronic lower-extremity wounds. METHODS: Adults presenting to 3 southeastern Michigan medical centers during the period February 15 through March 4, 2011, with chronic lower-extremity wounds had wound, nares, and perirectal swab specimens cultured for S. aureus and VRE, which were tested for pSK41-like and Inc18-like plasmids by polymerase chain reaction. We interviewed participants and reviewed clinical records. Risk factors for pSK41-positive S. aureus were assessed among all study participants (cohort analysis) and among only S. aureus-colonized participants (case-control analysis). RESULTS: Of 179 participants with wound cultures, 26% were colonized with methicillin-susceptible S. aureus, 27% were colonized with methicillin-resistant S. aureus, and 4% were colonized with VRE, although only 17% consented to perirectal culture. Six participants (3%) had pSK41-positive S. aureus, and none had Inc18-positive VRE. Having chronic wounds for over 2 years was associated with pSK41-positive S. aureus colonization in both analyses. CONCLUSIONS: Colonization with VRSA precursor organisms was rare. Having long-standing chronic wounds was a risk factor for pSK41-positive S. aureus colonization. Additional investigation into the prevalence of VRSA precursors among a larger cohort of patients is warranted. |
Methicillin-resistant Staphylococcus aureus colonization of the groin and risk for clinical infection among HIV-infected adults
Peters PJ , Brooks JT , McAllister SK , Limbago B , Lowery HK , Fosheim G , Guest JL , Gorwitz RJ , Bethea M , Hageman J , Mindley R , McDougal LK , Rimland D . Emerg Infect Dis 2013 19 (4) 623-629 Data on the interaction between methicillin-resistant Staphylococcus aureus (MRSA) colonization and clinical infection are limited. During 2007-2008, we enrolled HIV-infected adults in Atlanta, Georgia, USA, in a prospective cohort study. Nares and groin swab specimens were cultured for S. aureus at enrollment and after 6 and 12 months. MRSA colonization was detected in 13%-15% of HIV-infected participants (n = 600, 98% male) at baseline, 6 months, and 12 months. MRSA colonization was detected in the nares only (41%), groin only (21%), and at both sites (38%). Over a median of 2.1 years of follow-up, 29 MRSA clinical infections occurred in 25 participants. In multivariate analysis, MRSA clinical infection was significantly associated with MRSA colonization of the groin (adjusted risk ratio 4.8) and a history of MRSA infection (adjusted risk ratio 3.1). MRSA prevention strategies that can effectively prevent or eliminate groin colonization are likely necessary to reduce clinical infections in this population. |
Evaluation of the impact of direct plating, broth enrichment, and specimen source on recovery and diversity of methicillin-resistant Staphylococcus aureus among HIV-infected outpatients
McAllister SK , Albrecht VS , Fosheim GE , Lowery HK , Peters PJ , Gorwitz R , Guest JL , Hageman J , Mindley R , McDougal LK , Rimland D , Limbago B . J Clin Microbiol 2011 49 (12) 4126-30 We compared recovery of Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) from nasal and groin swabs of 600 HIV-infected outpatients by selective and non-selective direct plating and broth enrichment. Swabs were collected at baseline, 6-month and 12-month visits, cultured by direct plating to Mannitol Salt Agar (MSA), CHROMagar MRSA (CM), and overnight broth enrichment with sub-culture to MSA (Broth). MRSA isolates were characterized by pulsed-field gel electrophoresis (PFGE), SCCmec typing and PCR for the Panton-Valentine leukocidin. At each visit 13-15% of patients were colonized with MRSA and 30-33% with methicillin-susceptible S. aureus (MSSA). Broth, CM and MSA detected 95%, 82% and 76% of MRSA-positive specimens, respectively. MRSA recovery was significantly higher from Broth compared to CM (p ≤ 0.001) or MSA (p ≤ 0.001); there was no significant difference in recovery between MSA and CM. MSSA recovery also increased significantly using Broth compared to MSA (p ≤ 0.001). Among specimens collected from the groin, Broth, CM, and MSA detected 88%, 54%, and 49% of the MRSA-positive isolates, respectively. Broth enrichment had a greater impact on recovery of MRSA from the groin than from the nose compared to both CM (p ≤ 0.001) and MSA (p ≤ 0.001). Overall, 19% of MRSA-colonized patients would have been missed with nasal culture only. USA500/Iberian and USA300 were the most common MRSA strains recovered, and USA300 was more likely than other strain types to be recovered from the groin than from the nose (p=0.05). |
Emergence of resistance among USA300 methicillin-resistant Staphylococcus aureus isolates causing invasive disease in the United States
McDougal LK , Fosheim GE , Nicholson A , Bulens SN , Limbago BM , Shearer JE , Summers AO , Patel JB . Antimicrob Agents Chemother 2010 54 (9) 3804-11 USA300 methicillin-resistant Staphylococcus aureus (MRSA) isolates are usually resistant only to oxacillin, erythromycin, and, increasingly, levofloxacin. Of these, oxacillin and levofloxacin resistances are chromosomally encoded. Plasmid-mediated clindamycin, mupirocin, and/or tetracycline resistance has been observed among USA300 isolates, but these descriptions were limited to specific patient populations or isolated occurrences. We examined the antimicrobial susceptibilities of invasive MRSA isolates from a national surveillance population in order to identify USA300 isolates with unusual, possibly emerging, plasmid-mediated antimicrobial resistance. DNA from these isolates was assayed for the presence of resistance determinants and the presence of a pSK41-like conjugative plasmid. Of 823 USA300 isolates, 72 (9%) were tetracycline resistant; 69 of these were doxycycline susceptible and tetK positive, and 3 were doxycycline resistant and tetM positive. Fifty-one (6.2%) isolates were clindamycin resistant and ermC positive; 22 (2.7%) isolates were high-level mupirocin resistant (mupA positive); 5 (0.6%) isolates were trimethoprim-sulfamethoxazole (TMP-SMZ) resistant, of which 4 were dfrA positive; and 7 (0.9%) isolates were gentamicin resistant and aac6'-aph2'' positive. Isolates with pSK41-like plasmids (n = 24) were positive for mupA (n = 19), dfrA (n = 6), aac6'-aph2'' (n = 6), tetM (n = 2), and ermC (n = 8); 20 pSK41-positive isolates were positive for two or more resistance genes. Conjugative transfer of resistance was demonstrated between four gentamicin- and mupirocin-resistant and three gentamicin- and TMP-SMZ-resistant USA300 isolates; transconjugants harbored a single pSK41-like plasmid, which was PCR positive for aac6'-aph2'' and either mupA and/or dfrA. USA300 and USA100 isolates from the same state with identical resistance profiles contained pSK41-like plasmids with indistinguishable restriction and Southern blot profiles, suggesting horizontal plasmid transfer between USA100 and USA300 isolates. |
Dissemination of an enterococcus Inc18-like vanA plasmid, associated with vancomycin-resistant Staphylococcus aureus
Zhu W , Murray PR , Huskins WC , Jernigan JA , McDonald LC , Clark NC , Anderson KF , McDougal LK , Hageman JC , Olsen-Rasmussen M , Frace M , Alangaden GJ , Chenoweth C , Zervos MJ , Robinson-Dunn B , Schreckenberger PC , Reller LB , Rudrik JT , Patel JB . Antimicrob Agents Chemother 2010 54 (10) 4314-20 Of the 9 vancomycin-resistant Staphylococcus aureus (VRSA) cases reported to date in the literature, 7 occurred in Michigan (MI). In 5 out of 7 of the Michigan VRSA cases, an Inc18-like vanA plasmid was identified in the VRSA isolate and/or an associated vancomycin-resistant Enterococcus (VRE) isolate from the same patient. This plasmid may play a critical role in the emergence of VRSA and analysis of the geographical distribution of VRE containing this plasmid may explain the observed prevalence of VRSA in MI. A total of 1,641 VRE from three separate collections were tested for the Inc18-like vanA plasmid by PCR for traA, repR, and vanA. All VRE from 2 MI institutions (N= 386), and between 60 to 70 VRE (N=883) from 17 institutions in 13 other states were tested. Fifteen isolates (3.9%) from MI were positive for an Inc18-like vanA plasmid (9 E. faecalis [12.5%], 3 E. faecium [1.0%], 2 E. avium, and 1 E. raffinosus). Six isolates (0.6%) from outside of MI were positive (3 E. faecalis [2.7%] and 3 E. faecium [0.4%]). Fourteen of the 15 plasmid-positive isolates from MI had the same Tn1546 insertion site location as those of the VRSA-associated Inc18 plasmid whereas 5 out of 6 plasmid-positive isolates from outside of MI differed in this characteristic. The one exception was an E. faecium isolate with a pulsed-field gel electrophoresis (PFGE) pattern that was indistinguishable from a plasmid-positive isolate from MI. Most plasmid-positive E. faecalis demonstrated diverse patterns by PFGE, with the exception of three pairs with indistinguishable patterns, suggesting the plasmid is mobile. Although VRE with the VRSA-associated Inc18-like vanA plasmid were more common in MI, they remain rare. Periodic surveillance of VRE for the plasmid may be useful in predicting occurrence of VRSA. |
Quantitative analysis and molecular fingerprinting of methicillin-resistant Staphylococcus aureus nasal colonization in different patient populations: a prospective, multicenter study
Mermel LA , Eells SJ , Acharya MK , Cartony JM , Dacus D , Fadem S , Gay EA , Gordon S , Lonks JR , Perl TM , McDougal LK , McGowan JE , Maxey G , Morse D , Tenover FC . Infect Control Hosp Epidemiol 2010 31 (6) 592-7 OBJECTIVES: To better understand the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) colonization or infection in different patient populations, to perform quantitative analysis of MRSA in nasal cultures, and to characterize strains using molecular fingerprinting. DESIGN: Prospective, multicenter study. SETTING: Eleven different inpatient and outpatient healthcare facilities. PARTICIPANTS: MRSA-positive inpatients identified in an active surveillance program; inpatients and outpatients receiving hemodialysis; inpatients and outpatients with human immunodeficiency virus (HIV) infection; patients requiring cardiac surgery; and elderly patients requiring long-term care. METHODS: Nasal swab samples were obtained from January 23, 2006, through July 27, 2007; MRSA strains were quantified and characterized by molecular fingerprinting. RESULTS: A total of 444 nares swab specimens yielded MRSA (geometric mean quantity, 794 CFU per swab; range, 3-15,000,000 CFU per swab). MRSA prevalence was 20% for elderly residents of long-term care facilities (25 of 125 residents), 16% for HIV-infected outpatients (78 of 494 outpatients), 15% for outpatients receiving hemodialysis (31 of 208 outpatients), 14% for inpatients receiving hemodialysis (86 of 623 inpatients), 3% for HIV-infected inpatients (5 of 161 inpatients), and 3% for inpatients requiring cardiac surgery (6 of 199 inpatients). The highest geometric mean quantity of MRSA was for inpatients requiring cardiac surgery (11,500 CFU per swab). An association was found between HIV infection and colonization with the USA300 or USA500 strain of MRSA ([Formula: see text]). The Brazilian clone was found for the first time in the United States. Pulsed-field gel electrophoresis patterns for 11 isolates were not compatible with known USA types or clones. CONCLUSION: Nasal swab specimens positive for MRSA had a geometric mean quantity of 794 CFU per swab, with great diversity in the quantity of MRSA at this anatomic site. Outpatient populations at high risk for MRSA carriage were elderly residents of long-term care facilities, HIV-infected outpatients, and outpatients receiving hemodialysis. |
A multicenter study to determine disk diffusion and broth microdilution criteria for prediction of high- and low-level mupirocin resistance in Staphylococcus aureus
Swenson JM , Wong B , Simor AE , Thomson RB , Ferraro MJ , Hardy DJ , Hindler J , Jorgensen J , Reller LB , Traczewski M , McDougal LK , Patel JB . J Clin Microbiol 2010 48 (7) 2469-75 Mupirocin susceptibility testing of Staphylococcus aureus has become more important as mupirocin is used more widely to suppress or eliminate S. aureus colonization and prevent subsequent healthcare- and community-associated infections. This multi-center study evaluated two susceptibility testing screening methods to detect high-level mupirocin resistance (HLR), broth microdilution (BMD) MIC of ≥ 512 mug/ml and a 6 mm zone diameter for a 200-mug disk diffusion (DD) test. Initial testing indicated that with Clinical and Laboratory Standards Institute methods for BMD and DD, optimal conditions for detection of mupirocin HLR were 24 hours of incubation and reading DD zone diameters with transmitted light. Using the presence or absence of mupA as the gold standard for HLR, the sensitivity and specificity of a single-well 256 mug/ml BMD test were 97 and 99%, and for the 200-mug disk test were 98 and 99%, respectively. Testing with two disks, 200 mug and 5 mug, was evaluated for distinguishing HLR isolates (MIC ≥ 512 mug/ml), low-level resistant (LLR) isolates (MIC 8-256 mug/ml), and susceptible isolates (MIC ≤ 4 mug/ml). Using no zone with both disks as an indication of HLR, and no zone with the 5-mug disk plus any zone with the 200-mug disk as LLR, only 3 of the 340 isolates were misclassified, with 3 susceptible isolates being classified as LLR. Use of standardized MIC or disk tests could enable the detection of emerging high- and low-level mupirocin resistance in S. aureus. |
Population structure of a hybrid clonal group of methicillin-resistant Staphylococcus aureus, ST239-MRSA-III
Smyth DS , McDougal LK , Gran FW , Manoharan A , Enright MC , Song JH , de Lencastre H , Robinson DA . PLoS One 2010 5 (1) e8582 The methicillin-resistant Staphylococcus aureus (MRSA) clonal group known as ST239-MRSA-III is notable for its hybrid origin and for causing sustained hospital epidemics worldwide since the late 1970s. We studied the population structure of this MRSA clonal group using a sample of 111 isolates that were collected over 34 years from 29 countries. Genetic variation was assessed using typing methods and novel ascertainment methods, resulting in approximately 15 kb of sequence from 32 loci for all isolates. A single most parsimonious tree, free of homoplasy, partitioned 28 haplotypes into geographically-associated clades, including prominent European, Asian, and South American clades. The rate of evolution was estimated to be approximately 100x faster than standard estimates for bacteria, and dated the most recent common ancestor of these isolates to the mid-20th century. Associations were discovered between the ST239 phylogeny and the ccrB and dru loci of the methicillin resistance genetic element, SCCmec type III, but not with the accessory components of the element that are targeted by multiplex PCR subtyping tools. In summary, the evolutionary history of ST239 can be characterized by rapid clonal diversification that has left strong evidence of geographic and temporal population structure. SCCmec type III has remained linked to the ST239 chromosome during clonal diversification, but it has undergone homoplasious losses of accessory components. These results provide a population genetics framework for the precise identification of emerging ST239 variants, and invite a re-evaluation of the markers used for subtyping SCCmec. |
Twenty-five year epidemiology of invasive methicillin-resistant Staphylococcus aureus (MRSA) isolates recovered at a burn center
Murray CK , Holmes RL , Ellis MW , Mende K , Wolf SE , McDougal LK , Guymon CH , Hospenthal DR . Burns 2009 35 (8) 1112-7 Over the past two decades, an epidemiologic emergence of methicillin-resistant Staphylococcus aureus (MRSA) infections has occurred from that of primarily hospital-associated to community-associated. This emergence change has involved MRSA of different pulsed-field types (PFT), with different virulence genes and antimicrobial resistance patterns. In this study we, evaluate the changes in PFT and antimicrobial resistance epidemiology of invasive MRSA isolates over 25 years at a single burn unit. Isolates were tested by pulsed-field gel electrophoresis (PFGE), broth microdilution antimicrobial susceptibility testing, and PCR for the virulence factors Panton-Valentine leukocidin (PVL) and arginine catabolic mobile element (ACME), and the resistance marker staphylococcal chromosomal cassette mec (SCCmec). Forty isolates were screened, revealing stable vancomycin susceptibility MIC without changes over time but decreasing susceptibility to clindamycin and ciprofloxacin. The majority of PFGE types were MRSA USA800 carrying the SCCmec I element and USA100 carrying the SCCmec II element. No strains typically associated with community-associated MRSA, USA300 or USA400, were found. USA800 isolates were predominately found in the 1980s, USA600 isolates were primarily found in the 1990s, and USA100 isolates were found in the 2000s. The PVL gene was present in only one isolate, the sole USA500 isolate, from 1987. The virulence marker ACME was not detected in any of the isolates. Overall, a transition was found in hospital-associated MRSA isolates over the 25 years, but no introduction of community-associated MRSA isolates into this burn unit. Continued active surveillance and aggressive infection control strategies are recommended to prevent the spread of community-acquired MRSA to this burn unit. |
Pathogen profiling: rapid molecular characterization of Staphylococcus aureus by PCR/ESI-MS and correlation with phenotype
Wolk DM , Blyn LB , Hall TA , Sampath R , Ranken R , Ivy C , Melton R , Matthews H , White N , Li F , Harpin V , Ecker DJ , Limbago B , McDougal LK , Wysocki VH , Cai M , Carroll KC . J Clin Microbiol 2009 47 (10) 3129-37 There are few diagnostic methods that readily distinguish among community-acquired MRSA strains, now frequently transmitted within hospitals. We describe a rapid and high-throughput method for bacterial profiling of staphylococcal isolates. The method couples PCR to electrospray-ionization mass spectrometry (PCR/ESI-MS) and is performed on a platform suitable for use in a diagnostic laboratory. This profiling technology produces a high-resolution genetic signature indicative of the presence of specific genetic elements that represent distinctive phenotypic features. The PCR/ESI-MS signature accurately identified genotypic determinants consistent with phenotypic traits in well-characterized reference and clinical isolates of S. aureus. Molecular identification of the antibiotic resistance genes correlated strongly with phenotypic in vitro resistance. Identification of toxin genes correlated with independent PCR analysis for the toxin genes. Finally, isolates were correctly classified into genotypic groups that correlated with genetic clonal complexes, rep-PCR patterns, or pulsed-field gel electrophoresis types. The high-throughput PCR/ESI-MS assay should improve clinical management of staphylococcal infections. |
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