Community-associated Isolates Research Articles

Clonality and Persistence of Multiresistant Methicillin-Resistant Coagulase-Negative Staphylococci Isolated from the Staff of a University Veterinary Hospital.

The aim of this study was to characterize methicillin-resistant coagulase-negative staphylococci (MRCoNS) isolates from the healthy staff of a university veterinary hospital in order to assess their importance as a reservoir of antimicrobial resistance and to determine their population structure and evolution. The study duration was over two years (2020–2021), 94 individuals were analyzed in duplicate, and 78 strains were obtained. The overall prevalence of methicillin-resistant strains detected throughout the study was 61.7%, with point prevalence values of 53.2% in 2020 and 31.5% in 2021. A total of 19.1% of the individuals analyzed were carriers throughout the study. The most frequently identified MRCoNs were Staphylococcus epidermidis (92.3%) and S. warneri (3.8%). A total of 75.6% of the isolates obtained showed the development of multi-resistance, preferentially against erythromycin, gentamicin, and tetracycline, and to a lesser extent against fusidic acid, norfloxacin, and clindamycin; these antimicrobials are frequently used in the veterinary field. Although most of the S. epidermidis isolates obtained showed wide genetic variability and low dispersion, which are characteristic of community-associated isolates, a small number of strains spread between individuals in close physical proximity and were maintained over time, forming stable clones. These clones generally maintained the same type of staphylococcal cassette chromosome mec (SCCmec) and had a similar antimicrobial resistance pattern.

2404. Molecular Epidemiology of Clostridioides difficile in the United States, 2017

BackgroundIn 2009, the Centers for Disease Control and Prevention (CDC) implemented Clostridioides difficile infection (CDI) surveillance through the Emerging Infections Program (EIP) to monitor the incidence and evolving epidemiology of CDI in the United States. Since 2012, ribotypes (RTs) 027, 106, 002, 014, and 020 have constituted the top five strain types among both US community- and healthcare-associated isolates. Here we describe the changes in molecular epidemiology of C. difficile isolates collected in the United States in 2017.MethodsIn 2017, CDI surveillance was conducted at 10 EIP sites (CA, CO, CT, GA, MD, MN, NM, NY, OR, and TN). A convenience sample of clinical laboratories across EIP sites submitted C. difficile-positive stool specimens to the MN Department of Health Public Health Laboratory and Hines VA Hospital (IL) for culture. Isolates were forwarded to CDC and characterized by capillary-based PCR-ribotyping and PCR detection of tcdA, tcdB, cdtA, cdtB, and deletions in tcdC.ResultsIn 2017, 1,051 C. difficile isolates were submitted; the total number of isolates received from each site ranged from 11 to 286 with a median of 85.5. In total, 143 RTs were observed, with the majority of isolates harboring toxin genes tcdA and tcdB (95%) and a wild-type tcdC sequence (71%). Among 556 healthcare-associated isolates, RT 027 was the most prevalent and the top RT at 5 sites (CA, GA, MD, NM, TN). Ribotype 106 was the most prevalent among 495 community-associated CA isolates and the top RT at 6 sites (CO, CT, GA, MD, MN, TN). Ribotype 027 significantly decreased from 2012 to 2017 among both healthcare-associated (21% vs 15%; p = 0.02) and community-associated isolates (17% vs 6%; P < 0.0001). Among healthcare-associated isolates, RT 076, which was observed in 8 EIP sites, increased from 2% in 2016 to 5% in 2017 (p = 0.05) and replaced RT 020 as one of the top 5 healthcare-associated RTs in 2017.ConclusionDespite an overall decline since 2012, RT 027 remained the most prevalent RT among healthcare-associated isolates submitted in 2017. The increased frequency of RT 076 among healthcare-associated isolates submitted in 2017 highlights the evolving molecular epidemiology of C. difficile and the need for continued surveillance to monitor potential emerging strains.Disclosures All authors: No reported disclosures.

High prevalence of a globally disseminated hypervirulent clone, Staphylococcus aureus CC121, with reduced vancomycin susceptibility in community settings in China.

Most vancomycin-intermediate Staphylococcus aureus (VISA) and heterogeneous VISA (hVISA) are derived from hospital-associated MRSA due to treatment failure; however, the prevalence of hVISA/VISA in community settings remains unclear. Four hundred and seventy-six community-associated isolates were collected between 2010 and 2011 during national surveillance for antimicrobial resistance in 31 county hospitals across China. Drug susceptibility evaluation and mecA detection were performed by using broth microdilution and PCR analysis, respectively. hVISA/VISA were identified by using macro-Etest and a modified population analysis profile (PAP)-AUC method. The genetic features of all hVISA/VISA isolates were genotyped. Among 476 isolates, MRSA and MSSA accounted for 19.7% (n = 94) and 80.3% (n = 382), respectively. Two VISA and 36 hVISA isolates were identified by PAP-AUC testing. The VISA isolates and 29 of the hVISA isolates were MRSA. The proportion of hVISA/VISA was significantly higher in MRSA (30.9%) than in MSSA (1.8%). The hVISA/VISA isolates were assigned to 18 STs classified into seven clonal complexes (CCs). CC121 (n = 12) followed by ST239 (n = 11) was the most prevalent hVISA/VISA clone. All ST239-hVISA/VISA were MRSA, while 12 CC121-hVISA isolates included 6 MSSA and 6 MRSA isolates. SCCmec III was predominant among MRSA-hVISA/VISA isolates. agr I and agr IV were detected in ST239 and CC121, respectively. All except two strains were positive for Panton-Valentine leucocidin genes. To the best of our knowledge, this is the first report of CC121 as a prevalent hVISA clone in community settings, highlighting the necessity of surveillance and stricter infection control measures for this globally disseminated lineage.

The recent emergence in hospitals of multidrug-resistant community-associated sequence type 1 and spa type t127 methicillin-resistant Staphylococcus aureus investigated by whole-genome sequencing: Implications for screening.

Community-associated spa type t127/t922 methicillin-resistant Staphylococcus aureus (MRSA) prevalence increased from 1%-7% in Ireland between 2010–2015. This study tracked the spread of 89 such isolates from June 2013-June 2016. These included 78 healthcare-associated and 11 community associated-MRSA isolates from a prolonged hospital outbreak (H1) (n = 46), 16 other hospitals (n = 28), four other healthcare facilities (n = 4) and community-associated sources (n = 11). Isolates underwent antimicrobial susceptibility testing, DNA microarray profiling and whole-genome sequencing. Minimum spanning trees were generated following core-genome multilocus sequence typing and pairwise single nucleotide variation (SNV) analysis was performed. All isolates were sequence type 1 MRSA staphylococcal cassette chromosome mec type IV (ST1-MRSA-IV) and 76/89 were multidrug-resistant. Fifty isolates, including 40/46 from H1, were high-level mupirocin-resistant, carrying a conjugative 39 kb iles2-encoding plasmid. Two closely related ST1-MRSA-IV strains (I and II) and multiple sporadic strains were identified. Strain I isolates (57/89), including 43/46 H1 and all high-level mupirocin-resistant isolates, exhibited ≤80 SNVs. Two strain I isolates from separate H1 healthcare workers differed from other H1/strain I isolates by 7–47 and 12–53 SNVs, respectively, indicating healthcare worker involvement in this outbreak. Strain II isolates (19/89), including the remaining H1 isolates, exhibited ≤127 SNVs. For each strain, the pairwise SNVs exhibited by healthcare-associated and community-associated isolates indicated recent transmission of ST1-MRSA-IV within and between multiple hospitals, healthcare facilities and communities in Ireland. Given the interchange between healthcare-associated and community-associated isolates in hospitals, the risk factors that inform screening for MRSA require revision.

Community-onset extended-spectrum-β-lactamase-producing Escherichia coli sequence type 131 at two Korean community hospitals: The spread of multidrug-resistant E. coli to the community via healthcare facilities

BackgroundThe recent molecular epidemiology of ESBL-producing Escherichia coli infection in two Korean community hospitals was evaluated in this prospective observational study. MethodsWe collected non-duplicated E. coli isolates from consecutive, sequentially encountered patients with community-onset episodes between March and April 2016 in two community hospitals in Gyeonggi-do province, Korea. We studied the prevalence, clinical characteristics and molecular epidemiology of E. coli sequence type 131 (ST131) isolated from the community. ResultsFrom a total of 213 E. coli isolates collected from the community, 94 (44.1%) were community-onset healthcare-associated isolates and 119 (55.9%) were community-associated isolates, of which urinary tract infection was the majority. A total of 55 (25.8%) of the 213 E. coli isolates were confirmed to have ESBL genes, which were mainly CTX-M types such as CTX-M-14 and CTX-M-15. There was no difference in the proportion of globally epidemic ST131 clones or that of O25, O16, H30, or H30Rx subclones between community-associated and community-onset healthcare-associated isolates. ConclusionsIn this study, considerable ST131 E. coli isolations in the community were observed and about half of them were related to the history of a visit to the healthcare facilities, indicating the spread of multidrug-resistant E. coli to the community via healthcare facilities.

Molecular and epidemiologic study of Clostridium difficile reveals unusual heterogeneity in clinical strains circulating in different regions in Portugal

Clostridium difficile infection (CDI) represents a great healthcare burden in developed countries. The emergence of the epidemic PCR ribotype (RT) 027 and its acquired fluoroquinolones resistance have accentuated the need for an active surveillance of CDI. Here we report the first countrywide study of CDI in Portugal with the characterization of 498 C. difficile clinical isolates from 20 hospitals in four regions in Portugal regarding RT, virulence factors and antimicrobial susceptibility. We identified 96 RTs with marked variations between and within regions, as only six RTs appeared in all four regions. RT027 was the most frequent RT overall (18.5%) and among healthcare facility-associated isolates (19.6%), while RT014 was the most common among community-associated isolates (12%). The north showed a high RT diversity among isolates and a low moxifloxacin (MXF) resistance rate (11.9%), being the only region in which RT027 was not predominant. In contrast, the isolates from the centre presented the highest RT027 frequency, and 53.4% were resistant to MXF. Overall, MXF resistance (33.2%) was associated (p <0.001) with the presence of binary toxin genes and mutations in tcdC regardless of the RT. Both traits appeared in almost 30% of the strains. RT027 showed a reduced susceptibility to metronidazole (p <0.01), and RT126 had higher minimum inhibitory concentrations to vancomycin (p = 0.03) compared to other RTs. The present study highlights an unusual heterogeneity of RTs in Portugal, with a high frequency of hypervirulent RTs and the emergence of virulence factors in non-027 RTs, emphasizing the need for a surveillance system for CDI in Portugal.

Escherichia coliSequence Type 131 Is a Dominant, Antimicrobial-Resistant Clonal Group Associated with Healthcare and Elderly Hosts

To determine prevalence, predictors, and outcomes of infection due to Escherichia coli sequence type ST131. Retrospective cohort. All healthcare settings in Olmsted County, Minnesota (eg, community hospital, tertiary care center, long-term care facilities, and ambulatory clinics). Ambulatory and hospitalized children and adults with extraintestinal E. coli isolates. We analyzed 299 consecutive, nonduplicate extraintestinal E. coli isolates submitted to Olmsted County laboratories in February and March 2011. ST131 was identified using single-nucleotide polymorphism polymerase chain reaction and further evaluated through pulsed-field gel electrophoresis. Associated clinical data were abstracted through medical record review. Most isolates were from urine specimens (90%), outpatients (68%), and community-associated infections (61%). ST131 accounted for 27% of isolates overall and for a larger proportion of those isolates resistant to fluoroquinolones (81%), trimethoprim-sulfamethoxazole (42%), gentamicin (79%), and ceftriaxone (50%). The prevalence of ST131 increased with age (accounting for 5% of isolates from those 11-20 years of age, 26% of isolates from those 51-60 years of age, and 50% of isolates from those 91-100 years of age). ST131 accounted for a greater proportion of healthcare-associated isolates (49%) than community-associated isolates (15%) and for fully 76% of E. coli isolates from long-term care facility (LTCF) residents. Multivariable predictors of ST131 carriage included older age, LTCF residence, previous urinary tract infection, high-complexity infection, and previous use of fluoroquinolones, macrolides, and extended-spectrum cephalosporins. With multivariable adjustment, ST131-associated infection outcomes included receipt of more than 1 antibiotic (odds ratio [OR], 2.54 [95% confidence interval (CI), 1.25-5.17]) and persistent or recurrent symptoms (OR, 2.53 [95% CI, 1.08-5.96]). Two globally predominant ST131 pulsotypes accounted for 45% of ST131 isolates. ST131 is a dominant, antimicrobial-resistant clonal group associated with healthcare settings, elderly hosts, and persistent or recurrent symptoms.

Molecular and phenotypic characterization of hospital-associated and community-associated isolates of Enterococcus spp.

Objectives The aim of our study was to estimate the extent of spread of enterococcal infection as well as vancomycin-resistant enterococci (VRE) colonization at Menofia University Hospitals. and also to delineate occurrence and species prevalence, characterize VRE phenotypes and genotypes by multiplex PCR, and detect esp virulence genes in the enterococcal isolates from different sources. Background Enterococci are part of normal intestinal flora of both humans and animals; however, they have also emerged as significant community-acquired pathogens and are a leading cause of nosocomial infection. Patients and methods In this study, patients were classified into three groups. Group 1 included 195 hospitalized patients. Group 2 included 65 patients from group 1 and group 3 included 50 healthy individuals to detect VRE colonization. Culture was performed using selective media for enterococci (bile esculine agar); detection of the antibiotic susceptibility pattern for enterococcal isolates and detection of VRE were performed. Detection of vanA and vanB genes in VRE using multiplex PCR and PCR detection of the esp gene were also performed. Results The most commonly isolated Enterococcus spp. were Enterococcus faecium (48%) followed by Enterococcus faecalis (32%), Enterococcus durans (12%), Enterococcus avium, and Enterococcus gallinarum (4%). Of the 36 enterococcal isolates, 22 (61.1%) were identified as VRE by minimum inhibitory concentration. The Van A genotype was more common than van B. Of the 36 enterococcal isolates, 16 (77.82%) isolates had the esp gene. A high percentage (10.7%) of hospitalized patients showed colonization with VRE. The occurrence of the esp gene was higher in VRE clinical isolates of group I patients than isolates in stool specimens of patients in group II. Conclusion E. faecium is more common than E. faecalis as a nosocomial pathogen and it also has a great ability to show drug resistance. Emergence of multidrug-resistant enterococci to high-level aminoglycoside and vancomycin is an alarming situation. Fortunately, all VRE isolates are susceptible to linezolid. The Van A genotype is the predominant genotype among different species. A higher rate of gastrointestinal tract colonization by VRE is detected in hospitalized patients.

Incidence of Antibiotic-Resistant Escherichia coli Bacteriuria According to Age and Location of Onset: A Population-Based Study From Olmsted County, Minnesota

ObjectiveTo better understand the epidemiology of drug-resistant Escherichia coli across health care and community settings. Patients and MethodsWe conducted a population-based cohort study of the incidence of antibiotic-resistant E coli bacteriuria among different patient groups. All urine cultures with monomicrobial growth of E coli obtained from Olmsted County, Minnesota, residents from January 1, 2005, through December 31, 2009, were identified. The initial isolate per patient per year was included. Analyses were stratified by patient age and location of infection onset (ie, nosocomial, health care associated, and community associated). ResultsWe evaluated 5619 E coli isolates and the associated patients. During the study period, the incidence of drug-resistant bacteriuria did not change among children but increased significantly among adults of all ages, most markedly among elderly patients older than 80 years. In elderly patients, the incidence of bacteriuria with isolates resistant to fluoroquinolones increased from 464 to 1116 per 100,000 person-years (P<.001), and the incidence of bacteriuria with isolates resistant to fluoroquinolones plus trimethoprim-sulfamethoxazole increased from 274 to 512 per 100,000 person-years (P<.05). When analyzed by location of infection onset, incidence of bacteriuria with isolates resistant to trimethoprim-sulfamethoxazole, fluoroquinolones, trimethoprim-sulfamethoxazole plus fluoroquinolones, extended-spectrum cephalosporins, and more than 3 drug classes increased significantly among community-associated but not among nosocomial or health care–associated cases. ConclusionIn this population-based study, the incidence of antibiotic-resistant E coli bacteriuria nearly doubled during the 5-year study period among elderly patients and those with community-associated isolates. These patient groups should be targets of interventions to slow the emergence and spread of antibiotic-resistant E coli.

Antibiotic Options for Treatment of Pediatric Infections with Enterobacteriaceae Producing Broad Spectrum Beta-Lactamases

Enterobacteriaceae are major pediatric pathogens, but little is known regarding treatment options for multidrug-resistant strains. In this study, we investigated the susceptibility patterns of healthcare- and community-associated Enterobacteriaceae isolates expressing plasmid-borne, broad-spectrum beta-lactam resistance (PBLR). Using E-test methodology, we tested susceptibility to imipenem, meropenem, ertapenem, doripenem, piperacillin-tazobactam, minocycline, tigecycline, fosfomycin, and colistin in all 90 clinical isolates (Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca and Salmonella enterica) which are derived from urine (n=62), blood (n=12), and other specimens (n=16). These strains are confirmed to carry PBLR determinants. Although malignancy, urogenital and neurological diseases, and multiple antibiotic exposure were present in most patients, twenty three isolates (26%) were characterized as communityassociated. Enterobacteriaceae isolates expressing PBLR retained in vitro susceptibility to colistin (100%), minocycline (72%), tigecycline (97%), and fosfomycin (92%). Five unlinked isolates (6%; two isolates of E. coli and three of K. pneumoniae) showed resistance to one or all carbapenem agents. All community-associated isolates were susceptible to carbapenems and exhibited greater susceptibility to other agents compared to healthcare-associated isolates. In our study population, carbapenems remained broadly active and colistin, fosfomycin, and tigecycline demonstrated therapeutic potential against PBLR-positive isolates. Our findings have implications for susceptibility testing and empirical antimicrobial strategies targeting serious pediatric infections.

Near absence of methicillin-resistance and pronounced genetic diversity among Staphylococcus epidermidis isolated from healthy persons in northern Sweden

The main aim of this study was to examine if hospital-associated clones of multidrug-resistant Staphylococcus epidermidis (MDRSE), commonly identified in hospitals in our region, also are spread among healthy persons in the community. A total of 124 isolates of S. epidermidis sampled from subjects attending a Travel health clinic, Umeå, Sweden during 2008 were examined with antibiotic susceptibility testing and pulsed-field gel electrophoresis (PFGE) analysis. Resistance to methicillin or any antibiotic was detected in 2 and 26 of the isolates, respectively. PFGE analysis showed an extensive genetic diversity with 86 different PFGE types, 62 of which were singletons. No isolates belonged to the previously described hospital-associated MDRSE genotypes, indicating that MDRSE by large are confined to the hospital setting in our region. In conclusion, community-associated isolates of S. epidermidis showed a low level of methicillin-resistance and were genetically extremely diverse with no predominating genotype.

Incidence and Antimicrobial Susceptibility of Escherichia coli and Klebsiella pneumoniae with Extended-Spectrum β-Lactamases in Community- and Hospital-Associated Intra-Abdominal Infections in Europe: Results of the 2008 Study for Monitoring Antimicrobial Resistance Trends (SMART)

From 2002 to 2008, there was a significant increase in extended-spectrum beta-lactamase (ESBL)-positive Escherichia coli isolates in European intra-abdominal infections, from 4.3% in 2002 to 11.8% in 2008 (P < 0.001), but not for ESBL-positive Klebsiella pneumoniae isolates (16.4% to 17.9% [P > 0.05]). Hospital-associated isolates were more common than community-associated isolates, at 14.0% versus 6.5%, respectively, for E. coli (P < 0.001) and 20.9% versus 5.3%, respectively, for K. pneumoniae (P < 0.01). Carbapenems were consistently the most active drugs tested.

Contrasting Pediatric and Adult Methicillin-resistantStaphylococcus aureusIsolates

We performed a prospective study of all inpatient and outpatient methicillin-resistant Staphylococcus aureus (MRSA) isolates identified at the University of Chicago Hospitals from November 2003 through November 2004. Differences in resistance to non-beta-lactam antimicrobial drugs were determined after stratification of the 578 MRSA isolates into 4 groups by patient age (pediatric vs. adult) and onset location (community vs. hospital). Non-beta-lactam resistance was significantly greater among the 288 adult than the 177 pediatric community-associated isolates for erythromycin (93.2 vs. 87.0%, p = 0.03), clindamycin (51.8 vs. 7.3%, p<0.001), ciprofloxacin (62.1 vs. 10.7%, p<0.001), gentamicin (11.1 vs. 1.1%, p<0.001), and tetracycline (19.9 vs. 6.4%, p<0.001). In contrast, hospital-associated MRSA isolates from children and adults had similar rates of non-beta-lactam antimicrobial drug resistance. In our region, clindamycin is an appropriate empiric therapy of community-associated MRSA infection in children but should be used with caution in adults.

Use of Ribotyping To Retrospectively Identify Methicillin-Resistant Staphylococcus aureus Isolates from Phase 3 Clinical Trials for Tigecycline That Are Genotypically Related to Community-Associated Isolates

A retrospective study was performed to identify methicillin-resistant Staphylococcus aureus (MRSA) isolates obtained from patients enrolled in phase 3 clinical trials for tigecycline that were genotypically similar to known community-associated MRSA (CA-MRSA) strains. The clinical trials were double-blind comparator studies for complicated skin and skin structure infections or complicated intra-abdominal infections. We obtained 85% of the MRSA isolates from patients with complicated skin and skin structure infections. Using ribotyping, MRSA isolates were compared with well-characterized North American CA-MRSA strains and negative-control hospital-associated (HA) MRSA strains by cluster analysis; 91 of the 173 isolates clustered with two groups of known CA-MRSA strains, 60% of which shared an indistinguishable ribotype. These isolates were subsequently tested for the presence of SCCmec type IV and the Panton-Valentine leukocidin (PVL)-encoding genes as well as susceptibility to clindamycin, characteristics that are typically associated with CA-MRSA; 89 of the 91 isolates carried the type IV SCCmec element and 76 were also positive for the PVL-encoding genes; 73 of these isolates were susceptible to clindamycin. A similar analysis performed on 26 nonclustering isolates identified only four with these characteristics; 89 of the 91 clustering isolates were inhibited by tigecycline at MICs of < or = 0.5 microg/ml. On the basis of clustering information and preliminary genetic characterization, it appears that ribotyping is a useful tool in identifying potential CA-MRSA isolates and 76 MRSA isolates from patients enrolled in the tigecycline phase 3 trials have genetic markers typically associated with CA-MRSA.

Emergence of community-associated methicillin-resistant Staphylococcus aureus at a Memphis, Tennessee Children's Hospital.

An epidemiologic investigation was performed because of a perceived increase in infections caused by community-associated methicillin-resistant Staphylococcus aureus (MRSA) among children in the greater Memphis area. We reviewed medical records of 289 children evaluated from January 2000 to June 2002 at a children's hospital. Clinical criteria were applied to classify MRSA isolates as community-associated (n=51) or health care-associated (n=138). The relatedness of 33 archived S. aureus isolates was evaluated using pulsed field gel electrophoresis (PFGE) of Sma I-digested genomic DNA; a common pulsed field type was defined as > or = 80 % similarity based on Dice coefficients. PFGE profiles were compared with those in a national database of MRSA isolates. During the first 18 study months, 46 of 122 MRSA isolates (38%) were community-associated; this proportion increased to 106 of 167 isolates (63%) during the last 12 study months (P <.0001). Community-associated isolates were recovered from normally sterile sites as frequently as were health care-associated isolates (16% versus 13%). PFGE revealed that 15 of 16 community-associated isolates shared a common pulsed field type (USA300) observed in community-associated MRSA infections elsewhere in the United States and characterized by staphylococcal cassette chromosome mec type IV, clindamycin susceptibility and erythromycin resistance mediated by an msr A-encoded macrolide efflux pump. Community-associated MRSA has emerged as a potentially invasive pathogen among children in the greater Memphis area, and this phenomenon is not explained by spread of nosocomial strains into the community.