We thank Gonzales-Luna and colleagues [1] for their comments. We agree that laboratories must have access to accurate and standardized methods for antimicrobial susceptibility testing (AST) results to be clinically meaningful. The reference method for performing Clostridioides difficile AST is agar dilution according to Clinical and Laboratory Standards Institute (CLSI) guidelines [2]. The CLSI method for performing AST for anaerobic bacteria recommends that 5 μg/mL of hemin be incorporated into agar dilution plates and that the hemin stock solution should be protected from light and stored at 4°C–8°C for no longer than 1 month [2]. The susceptibility testing done by Gargis et al [3] was performed according to these guidelines, and the hemin stock solution was protected from light. | | Nevertheless, we read with interest the research in recent years [4–6] related to heme-dependent metronidazole resistance, including the reported association between isolates characterized as heme dependent and metronidazole resistant and the presence of a T to G mutation (PnimBG) in the −10 promoter region of the nitroimidazole reductase gene, nimB [5]. While Olaitan et al [5] found that not all heme-dependent metronidazole-resistant isolates contained the PnimBG mutation, Olaitan et al [5] indicate that most do; therefore, the presence of PnimBG may be predictive of resistance. We determined that the nimB mutation was present in 20% of our study isolates (116 of 593), of which 99% (115 of 116) belonged to RT027 (Table 1). The remaining isolate was RT014, the only RT014 isolate containing the PnimBG mutation among the 65 evaluated.

Carbapenem-resistant Enterobacterales (CRE) are an urgent public health threat. Genomic sequencing is an important tool for investigating CRE. Through the Division of Healthcare Quality Promotion Sentinel Surveillance system, we collected CRE and carbapenem-susceptible Enterobacterales (CSE) from nine clinical laboratories in the USA from 2013 to 2016 and analysed both phenotypic and genomic sequencing data for 680 isolates. We describe the molecular epidemiology and antimicrobial susceptibility testing (AST) data of this collection of isolates. We also performed a phenotype-genotype correlation for the carbapenems and evaluated the presence of virulence genes in Klebsiella pneumoniae complex isolates. These AST and genomic sequencing data can be used to compare and contrast CRE and CSE at these sites and serve as a resource for the antimicrobial resistance research community.

During May 2018‒December 2022, we reviewed transfusion-transmitted sepsis cases in the United States attributable to polymicrobial contaminated apheresis platelet components, including Acinetobacter calcoaceticus‒baumannii complex or Staphylococcus saprophyticus isolated from patients and components. Transfused platelet components underwent bacterial risk control strategies (primary culture, pathogen reduction or primary culture, and secondary rapid test) before transfusion. Environmental samples were collected from a platelet collection set manufacturing facility. Seven sepsis cases from 6 platelet donations from 6 different donors were identified in patients from 6 states; 3 patients died. Cultures identified Acinetobacter calcoaceticus‒baumannii complex in 6 patients and 6 transfused platelets, S. saprophyticus in 4 patients and 4 transfused platelets. Whole-genome sequencing showed environmental isolates from the manufacturer were closely related genetically to patient and platelet isolates, indicating the manufacturer was the most probable source of recurrent polymicrobial contamination. Clinicians should maintain awareness of possible transfusion-transmitted sepsis even when using bacterial risk control strategies.

BACKGROUND: Antimicrobial susceptibility testing (AST) is not routinely performed for Clostridioides difficile and data evaluating minimum inhibitory concentrations (MICs) are limited. We performed AST and whole genome sequencing (WGS) for 593 C. difficile isolates collected between 2012-2017 through the Centers for Disease Control and Prevention's Emerging Infections Program. METHODS: MICs to six antimicrobial agents (ceftriaxone, clindamycin, meropenem, metronidazole, moxifloxacin, and vancomycin) were determined using the reference agar dilution method according to Clinical and Laboratory Standards Institute guidelines. WGS was performed on all isolates to detect the presence of genes or mutations previously associated with resistance. RESULTS: Among all isolates, 98.5% displayed a vancomycin MIC ≤ 2 μg/mL and 97.3% displayed a metronidazole MIC ≤ 2 μg/mL. Ribotype 027 (RT027) isolates displayed higher vancomycin MICs (MIC50: 2 μg/mL; MIC90: 2 μg/mL) than non-RT027 isolates (MIC50: 0.5 μg/mL; MIC90: 1 μg/mL) (P < 0.01). No vanA/B genes were detected. RT027 isolates also showed higher MICs to clindamycin and moxifloxacin and were more likely to harbor associated resistance genes or mutations. CONCLUSIONS: Elevated MICs to antibiotics used for treatment of C. difficile infection were rare and there was no increase in MICs over time. The lack of vanA/B genes or mutations consistently associated with elevated vancomycin MICs suggests there are multifactorial mechanisms of resistance. Ongoing surveillance of C. difficile using reference AST and WGS to monitor MIC trends and the presence of antibiotic resistance mechanisms is essential.

Enterococcus faecalis and faecium with resistance to daptomycin and/or linezolid are emerging globally. We present the genomic characterization of daptomycin- and linezolid-resistant E. faecalis and E. faecium surveillance isolates from the United States, 2013-2016. Daptomycin resistance was low among E. faecalis (2/364, 0.5%) and E. faecium (17/344, 5%). The majority (71%, 12/17) of daptomycin-resistant E. faecium isolates belonged to the emerging ST736 clone and contained mutations in liaFSR and cls previously associated with resistance. However, 1/2 E. faecalis and 3/17 E. faecium did not contain these mutations previously associated with daptomycin resistance. Linezolid resistance was rare among E. faecalis (1/364, 0.3%) and E. faecium (2/344, 0.6%). These two E. faecium isolates, one of which was also resistant to daptomycin and vancomycin, contained the 23S rRNA nucleotide mutation (G2576T) associated with linezolid resistance. Long-read sequencing revealed the linezolid-resistant E. faecalis isolate contained chromosomal- and plasmid-encoded copies of optrA. The chromosomal optrA was located on the recently described Tn6674 multiresistance transposon. The second copy of optrA was encoded on an ∼65 kb mosaic plasmid, with component regions sharing high sequence identity to optrA-encoding multiresistance plasmids of animal origin. The optrA-encoding plasmid contained open reading frames predicted to encode proteins associated with a pheromone-responsive plasmid transfer system, and filter mating experiments confirmed the plasmid was conjugative. Continued surveillance of enterococci is necessary to assess the prevalence and trends of daptomycin and linezolid resistance in the United States, characterize resistance mechanisms and how they transfer, and monitor for emerging sequence types associated with resistance.

OBJECTIVES: In December 2020, CDC launched the Pharmacy Partnership for Long-Term Care Program to facilitate COVID-19 vaccination of residents and staff in long-term care facilities (LTCFs), including assisted living (AL) and other residential care (RC) communities. We aimed to assess vaccine uptake in these communities and identify characteristics that might impact uptake. DESIGN: Cross-sectional study. SETTING AND PARTICIPANTS: AL/RC communities in the Pharmacy Partnership for Long-Term Care Program that had ≥1 on-site vaccination clinic during December 18, 2020-April 21, 2021. METHODS: We estimated uptake by using the cumulative number of doses of COVID-19 vaccine administered and normalizing by the number of AL/RC community beds. We estimated the percentage of residents vaccinated in 3 states using AL census counts. We linked community vaccine administration data with county-level social vulnerability index (SVI) measures to calculate median vaccine uptake by SVI tertile. RESULTS: In AL communities, a median of 67 residents [interquartile range (IQR): 48-90] and 32 staff members (IQR: 15-60) per 100 beds received a first dose of COVID-19 vaccine at the first on-site clinic; in RC, a median of 8 residents (IQR: 5-10) and 5 staff members (IQR: 2-12) per 10 beds received a first dose. Among 3 states with available AL resident census data, median resident first-dose uptake at the first clinic was 93% (IQR: 85-108) in Connecticut, 85% in Georgia (IQR: 70-102), and 78% (IQR: 56-91) in Tennessee. Among both residents and staff, cumulative first-dose vaccine uptake increased with increasing social vulnerability related to housing type and transportation. CONCLUSIONS AND IMPLICATIONS: COVID-19 vaccination of residents and staff in LTCFs is a public health priority. On-site clinics may help to increase vaccine uptake, particularly when transportation may be a barrier. Ensuring steady access to COVID-19 vaccine in LTCFs following the conclusion of the Pharmacy Partnership is critical to maintaining high vaccination coverage among residents and staff.

The coronavirus disease 2019 (COVID-19) pandemic has highlighted the vulnerability of residents and staff members in long-term care facilities (LTCFs) (1). Although skilled nursing facilities (SNFs) certified by the Centers for Medicare & Medicaid Services (CMS) have federal COVID-19 reporting requirements, national surveillance data are less readily available for other types of LTCFs, such as assisted living facilities (ALFs) and those providing similar residential care. However, many state and territorial health departments publicly report COVID-19 surveillance data across various types of LTCFs. These data were systematically retrieved from health department websites to characterize COVID-19 cases and deaths in ALF residents and staff members. Limited ALF COVID-19 data were available for 39 states, although reporting varied. By October 15, 2020, among 28,623 ALFs, 6,440 (22%) had at least one COVID-19 case among residents or staff members. Among the states with available data, the proportion of COVID-19 cases that were fatal was 21.2% for ALF residents, 0.3% for ALF staff members, and 2.5% overall for the general population of these states. To prevent the introduction and spread of SARS-CoV-2, the virus that causes COVID-19, in their facilities, ALFs should 1) identify a point of contact at the local health department; 2) educate residents, families, and staff members about COVID-19; 3) have a plan for visitor and staff member restrictions; 4) encourage social (physical) distancing and the use of masks, as appropriate; 5) implement recommended infection prevention and control practices and provide access to supplies; 6) rapidly identify and properly respond to suspected or confirmed COVID-19 cases in residents and staff members; and 7) conduct surveillance of COVID-19 cases and deaths, facility staffing, and supply information (2).