Epidemiology, species distribution, and outcome of nosocomial Candida spp. bloodstream infection in Shanghai: an 11-year retrospective analysis in a tertiary care hospital.

BACKGROUND: The incidence of Candida bloodstream infections (BSIs), has increased over time. In this study, we aimed to describe the current epidemiology of Candida BSI in a large tertiary care hospital in Shanghai and to determine the risk factors of 28-day mortality and the impact of antifungal therapy on clinical outcomes. METHODS: All consecutive adult inpatients with Candida BSI at Ruijin Hospital between January 1, 2008, and December 31, 2018, were enrolled. Underlying diseases, clinical severity, species distribution, antifungal therapy, and their impact on the outcomes were analyzed. RESULTS: Among the 370 inpatients with 393 consecutive episodes of Candida BSI, the incidence of nosocomial Candida BSI was 0.39 episodes/1000 hospitalized patients. Of the 393 cases, 299 (76.1%) were treated with antifungal therapy (247 and 52 were treated with early appropriate and targeted antifungal therapy, respectively). The overall 28-day mortality rate was 28.5%, which was significantly lower in those who received early appropriate (25.5%) or targeted (23.1%) antifungal therapy than in those who did not (39.4%; P = 0.012 and P = 0.046, respectively). In multivariate Cox regression analysis, age, chronic renal failure, mechanical ventilation, and severe neutropenia were found to be independent risk factors of the 28-day mortality rate. Patients who received antifungal therapy had a lower mortality risk than did those who did not. CONCLUSIONS: The incidence of Candida BSI has increased steadily in the past 11 years at our tertiary care hospital in Shanghai. Antifungal therapy influenced short-term survival, but no significant difference in mortality was observed between patients who received early appropriate and targeted antifungal therapy.

First report of Klebsiella oxytoca strain coproducing KPC-2 and IMP-8 carbapenemases.

The study shows for the first time the presence of the Klebsiella oxytoca strain fp10 coproducing plasmid-mediated KPC-2 and IMP-8 carbapenemases. The strain was obtained from the fecal sample of an inpatient and showed high-level resistance to imipenem and ertapenem (MICs > 32 µg/ml). Conjugation experiments demonstrated the transferability of the carbapenem-resistant determinants. The results of plasmid analysis and Southern hybridization revealed that the bla(KPC-2) gene was located on transferable plasmid pFP10-1 (∼54 kb), whereas the bla(IMP-8) gene was on transferable plasmid pFP10-2 (∼180 kb). Analysis of the genetic environment of these two genes has demonstrated that ISKpn6 and ISKpn8 are involved in the spread of the bla(KPC-2) gene, while the transposable elements IS26, intI1, and tniC might contribute to the dissemination of the bla(IMP-8) gene. The chimera of several transposon-associated elements indicated a novel genetic environment of IMP-type metallo-ß-lactamase gene in Enterobacteriaceae from China.

High prevalence of CTX-M ß-lactamases in faecal Escherichia coli strains from healthy humans in Fuzhou, China.

BACKGROUND: The community could be a reservoir of antibiotic resistance genes. The aim of this study was to investigate the prevalence and genetic environments of bla(CTX-M) among faecal Escherichia coli obtained from healthy persons in a region of China. METHODS: Bacteria in stool specimens were screened for extended-spectrum ß-lactamase (ESBL) production on 2 MacConkey agars, one with cefotaxime and one with ceftazidime. bla(CTX-M) and their genetic environments, as well as phylogenetic analysis and detection of the O25b-ST131 clone of E. coli, were characterized by polymerase chain reaction and sequencing. Pulsed field gel electrophoresis and conjugation assays were performed by standard procedures. RESULTS: A surprisingly high number (50.5%, 55/109) of faecal samples showed the presence of ESBL-producing E. coli. bla(CTX-M) genes were detected in all of these strains. The CTX-M-9 group (41/55, 74.5%) was found most frequently, followed by the CTX-M-1 group (16/55, 29.1%). CTX-M-14 (n = 39) was the predominant CTX-M enzyme in this study. However, the genes for the CTX-M-2 and CTX-M-8 groups were not observed. ISEcp1 was detected in 90.9% of the strains, while IS26 was observed upstream from bla(CTX-M) in only 1 strain. Phylogenetic groups A and D were found to predominate in commensal E. coli. High clonal diversity was observed and most bla(CTX-M) genes were transferable. The O25b-ST131 clone was found in 4 strains. CONCLUSIONS: This study reveals the wide dissemination of CTX-M ESBL-producing E. coli in the gut flora of healthy individuals in China.

An efficient and novel screening model for assessing the bioactivity of extracts against multidrug-resistant Pseudomonas aeruginosa using Caenorhabditis elegans.

As a large number of multidrug-resistant bacteria have emerged, and there is an urgent need for the development of new antibacterial agents. In this study, we developed a liquid-based slow killing assay to be carried out in standard 96-well microtiter plates. This screening method was designed to facilitate high-throughput screening of small molecules and extracts. In antibiotic rescue assays, the Caenorhabditis elegans multidrug-resistant Pseudomonas aeruginosa infection model displayed a high degree of drug resistance in vivo and in vitro. We used the method to screen 1,300 extracts, and found 36 extracts (2.7%) which prolonged the survival of infected nematodes, and four (0.3%) of these extracts showed in vitro and in vivo anti-multidrug resistant P. aeruginosa activity. These results indicate that the whole-animal C. elegans multidrug-resistant bacterial model can be used to screen antibacterial compounds, and can also be useful for bioactive compounds which most likely cannot be identified in vitro.

Molecular characteristics and risk factor analysis of Staphylococcus aureus colonization put insight into CC1 colonization in three nursing homes in Shanghai.

Research indicates that Staphylococcus aureus colonization in the elderly with predisposing risks is associated with subsequent infection. However, the molecular epidemiology and risk factors for S. aureus colonization among residents and staff in nursing homes (NHs) in China remain unclear. A multicenter study was conducted in three NHs in Shanghai between September 2019 and October 2019. We explored the prevalence, molecular epidemiology, and risk factors for S. aureus colonization. All S. aureus isolates were characterized based on antimicrobial resistance, virulence genes, multilocus sequence typing (MLST), staphylococcus protein A (spa) typing, and staphylococcal cassette chromosome mec (SCCmec) typing. NH records were examined for potential risk factors for S. aureus colonization. S. aureus and methicillin-resistant S. aureus (MRSA) isolates were detected in 109 (100 residents and 9 staff, 19.8%, 109/551) and 28 (24 residents and 4 staff, 5.1%, 28/551) subjects among 496 residents and 55 staff screened, respectively. Compared to methicillin-susceptible S. aureus isolates, all 30 MRSA isolates had higher resistance rates to most antibiotics except minocycline, rifampicin, linezolid, vancomycin, and teicoplanin. Sequence type (ST) 1 (21.3%) was the most common sequence type, and t127 (20.5%) was the most common spa type among 122 S. aureus isolates. SCCmec type I (70%) was the dominant clone among all MRSA isolates. CC1 (26/122, 21.3%) was the predominant complex clone (CC), followed by CC398 (25/122, 20.5%), CC5 (20/122, 16.4%) and CC188 (18/122, 14.8%). Female sex (OR, 1.70; 95% CI, 1.04-2.79; P = 0.036) and invasive devices (OR, 2.19; 95% CI, 1.26-3.81; P = 0.006) were independently associated with S. aureus colonization.

Phylogenetic groups and pathogenicity island markers in fecal Escherichia coli isolates from asymptomatic humans in China.

The study of phylogenetic groups and pathogenicity island (PAI) markers in commensal Escherichia coli strains from asymptomatic Chinese people showed that group A strains are the most common and that nearly half of all fecal strains which were randomly selected harbor PAIs.

Molecular Epidemiology and Antimicrobial Resistance of Haemophilus influenzae in Adult Patients in Shanghai, China.

Background: The serotype and antimicrobial resistance of Haemophilus influenzae in adult patients have changed due to the application of antimicrobials and H. influenzae type b (Hib) vaccine worldwide. However, the epidemiologic characteristics of H. influenzae in Shanghai are still unavailable. Objective: To determine the serotype distribution, antimicrobial resistance and multilocus sequence type (MLST) of H. influenzae in adult patients in Shanghai. Methods: A total of 51 clinical isolates from adult patients were consecutively collected. Serotypes were determined according to specific capsule gene, bexA, amplified by PCR. Antimicrobial susceptibility test was carried out by the broth microdilution method. ß-lactamase production was detected by cefinase disk and the ftsI gene were amplified and sequenced to determine the penicillin binding protein 3 (PBP3) mutation. Molecular epidemiology was performed by MLST analyses. Results: All isolates studied were nontypeable H. influenzae (NTHi) and three of them (5.88%) caused invasive infection. The resistant rates of ampicillin and trimethoprim/sulfamethoxazole were both 45.10%. One third of these isolates produced TEM-1 type ß-lactamase and 11.76% were ß-lactamase negative ampicillin resistant strains (BLNAR). The PBP3 mutation was detected in 74.51% of the isolates, of which 12 belonged to group III. A total of 36 sequence types (STs) were identified among all isolates. Four isolates of ST103 (7.84%) all produced ß-lactamase without mutation of PBP3. Conclusion:H. influenzae infections among adults in Shanghai are predominately caused by NTHi with genetic diversity among adult patients. The prevalence of both ß-lactamase production and PBP3 mutation may contribute to high ampicillin resistance rate in Shanghai.

Serotype Distribution, Antimicrobial Susceptibility, and Multilocus Sequencing Type (MLST) of Streptococcus pneumoniae From Adults of Three Hospitals in Shanghai, China.

Background:Streptococcus pneumoniae, a main causative agent associated with invasive and non-invasive infection in elderly population, is a major global health problem. After pneumococcal conjugate vaccines (PCV) and pneumococcal polysaccharide vaccines (PPV) were introduced, the distribution of S. pneumoniae serotypes has changed. There was currently limited data on epidemiology and status of antimicrobial resistance of S. pneumoniae in Shanghai. Objective: To determine the serotype distribution, antimicrobial susceptibility and molecular epidemiology of S. pneumoniae isolated from adults in Shanghai. Method: A total of 75 S. pneumoniae isolates consecutively collected from 2015 through 2017 were serotyped by conventional multiplex-PCR. The antimicrobial susceptibility was determined by broth microdilution method. The multilocus sequence type (MLST) was performed to estimate the molecular epidemiology. Results: The predominant serotypes among the isolates were 19F (20.00%), 3 (16.00%), 23F (9.33%), 14 (8.00%), and19A (5.33%). The prevalence of pneumococcal strains with serotypes targeted by vaccines PCV7, PCV10, PCV13, and PPV23 was 44, 45.33, 66.67, and 80%, respectively. Penicillin non-susceptible S. pneumoniae (PNSSP) accounted for 16% of the isolates examined and resistance to erythromycin, azithromycin, tetracycline, clindamycin, cefaclor and trimethoprim-sulfamethoxazole were found in 92.00, 90.67, 86.67, 81.33, 54.67, and 54.67% of isolates, with most isolates (78.67%) presenting multidrug-resistance. The top three sequence types (STs) were ST271 (17.33%), ST180 (9.33%), and ST81 (8.00%). The international resistance clone complexes Spain23F-1 (n = 4), Netherland3-31 (n = 8), and Taiwan19F-14 (n = 14) were identified. Conclusions: The S. pneumoniae isolates showed high genetic diversity in Shanghai and the prevalence of antimicrobial resistance was also high among S. pneumoniae isolates, most of which were multidrug-resistant. The spread of international resistance clones might contribute to the increase of resistant isolates. The PPV23 could protect against most pneumococcal capsular serotypes causing infection of adults in Shanghai.

Changes in antimicrobial susceptibility of commonly clinically significant isolates before and after the interventions on surgical prophylactic antibiotics (SPAs) in Shanghai.

Surveillances and interventions on antibiotics use have been suggested to improve serious drug-resistance worldwide. Since 2007, our hospital have proposed many measures for regulating surgical prophylactic antibiotics (carbapenems, third gen. cephalosporins, vancomycin, etc.) prescribing practices, like formulary restriction or replacement for surgical prophylactic antibiotics and timely feedback. To assess the impacts on drug-resistance after interventions, we enrolled infected patients in 2006 (pre-intervention period) and 2014 (post-intervention period) in a tertiary hospital in Shanghai. Proportions of targeted pathogens were analyzed: methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus spp. (VRE), imipenem-resistant Escherichia coli (IREC), imipenem-resistant Klebsiella pneumoniae (IRKP), imipenem-resistant Acinetobacter baumannii (IRAB) and imipenem-resistant Pseudomonas aeruginosa (IRPA) isolates. Rates of them were estimated and compared between Surgical Department, ICU and Internal Department during two periods. The total proportions of targeted isolates in Surgical Department (62.44%, 2006; 64.09%, 2014) were more than those in ICU (46.13%, 2006; 50.99%, 2014) and in Internal Department (44.54%, 2006; 51.20%, 2014). Only MRSA has decreased significantly (80.48%, 2006; 55.97%, 2014) (p<0.0001). The percentages of VRE and IREC in 3 departments were all <15%, and the slightest change were also both observed in Surgical Department (VRE: 0.76%, 2006; 2.03%, 2014) (IREC: 2.69%, 2006; 2.63%, 2014). The interventions on surgical prophylactic antibiotics can be effective for improving resistance; antimicrobial stewardship must be combined with infection control practices.

Antimicrobial Resistance and Molecular Characterization of Staphylococcus aureus Causing Childhood Pneumonia in Shanghai.

Staphylococcus aureus or methicillin-resistant Staphylococcus aureus (MRSA) is a major pathogen causing pneumonia among children. To estimate the prevalence and molecular properties of S. aureus in children pneumonia in Shanghai, China, 107 hospitalized children with S. aureus pneumonia from two children's hospitals from January 2014 through June 2015 were studied. S. aureus isolates from the respiratory specimens were characterized by antimicrobial susceptibility, agr typing, toxin genes, multilocus sequence typing (MLST), spa, and SCCmec typing. Fifty-eight (54.2%, 58/107) were MSSA (methicillin-susceptible Staphylococcus aureus) and 49 (45.8%, 49/107) were MRSA. No isolates were found resistant to teicoplanin, sulfamethoxazole/trimethoprim, rifampicin, quinupristin/dalfopristin, linezolid, or vancomycin. However, these isolates showed high resistant rates to erythromycin, fosfomycin-trometamol and clindamycin. The agrI (87/107, 81.3%) was the most common agr allele, followed by agrIII(10/107, 9.3%), agrII(9/107, 8.4%), and agrIV(1/107, 0.9%). Six pvl-positive isolates (3 MRSA and 3 MSSA) and 7 isolates of livestock associated clone ST398 (4 MRSA, 3 MSSA) were identified. CC59 was found in 35 isolates (33 MRSA and 2 MSSA), constituting majority of MRSA (33/49, 67.35%). The dominant CC were CC59 (32.7%), CC188 (13.1%), CC7 (12.1%) and CC398 (9.3%) while t172 (16.8%), t189 (12.1%), t437 (9.3%), and t091 (9.3%) were the most common spa types. In conclusion, more particular concern should appeal to ST59-SCCmecIV-t172/t437 as it is the most common epidemic clone causing pneumonia among children in Shanghai.

The Resistance Phenotype and Molecular Epidemiology of Klebsiella pneumoniae in Bloodstream Infections in Shanghai, China, 2012-2015.

Klebsiella pneumoniae (K.pneumoniae) is a common nosocomial pathogen causing bloodstream infections. Antibiotic susceptibility surveillance and molecular characterization will facilitate prevention and management of K. pneumoniae bloodstream infections. K. pneumoniae isolates causing bloodstream infections were consecutively collected between January 2012 and December 2015 in Shanghai. Eighty isolates (20 per year) were randomly selected and enrolled in this study. Drug susceptibility were determined by the disk diffusion method. Polymerase chain reaction (PCR) was employed to detect extended-spectrum ß-lactamases (ESBLs), carbapenemases, and seven housekeeping genes of K. pneumoniae. eBURST was used for multi-locus sequence typing (MLST). More than 50% isolates were resistant to cefuroxime, ampicillin-sulbactam, and piperacillin, while carbapenems had lower resistant rates than other antibiotics. Of the 80 isolates, 22 produced ESBLs, and 14 were carbapenemase producers. In the ESBL-producing K. pneumoniae isolates, the most common ESBL genes were blaSHV and blaCTX-M. Thirteen carbapenemase producers harbored blaKPC-2 and one other carried blaNDM-5. ST11 (14/80) was the most frequent sequence type (ST), followed by ST15 (7/80) and ST29 (4/80). Our data revealed high prevalence of antibiotic resistant K. pneumoniae isolates from bloodstream infections but their genetic diversity suggested no clonal dissemination in the region. Also, one K. pneumoniae isolate harbored blaNDM-5 in this study, which was firstly reported in Shanghai.

Antimicrobial susceptibility and molecular epidemiology of clinical Enterobacter cloacae bloodstream isolates in Shanghai, China.

BACKGROUND: Enterobacter cloacae is a major nosocomial pathogen causing bloodstream infections. We retrospectively conducted a study to assess antimicrobial susceptibility and phylogenetic relationships of E. cloacae bloodstream isolates in two tertiary university-affiliated hospitals in Shanghai, in order to facilitate managements of E. cloacae bloodstream infections and highlight some unknowns for future prevention. METHODS: Fifty-three non-duplicate E. cloacae bloodstream isolates were consecutively collected from 2013 to 2016. Antimicrobial susceptibility was determined by disk diffusion. PCR was performed to detect extended-spectrum ß-lactamase (ESBL), carbapenemase and colistin resistance (MCR-1) gene. Plasmid-mediated AmpC ß-lactamase (pAmpC) genes were detected using a multiplex PCR assay targeting MIR/ACT gene (closely related to chromosomal EBC family gene) and other plasmid-mediated genes, including DHA, MOX, CMY, ACC, and FOX. eBURST was applied to analyze multi-locus sequence typing (MLST). RESULTS: The rates of resistance to all tested antibiotics were <40%. Among 53 E. cloacae isolates, 8(15.1%) were ESBL producers, 3(5.7%) were carbapenemase producers and 18(34.0%) were pAmpC producers. ESBL producers bear significantly higher resistance to cefotaxime (100.0%), ceftazidime (100.0%), aztreonam (100.0%), piperacillin (87.5%), tetracycline (75.0%), and trimethoprim-sulfamethoxazole (62.5%) than non-producers (p<0.05). PAmpC- and non-producers both presented low resistance rates (<40%) to all antibiotics (p>0.05). SHV (6/8, 75.0%) and MIR/ACT (15/18, 83.3%) predominated in ESBL and pAmpC producers respectively. Moreover, 2 isolates co-carried TEM-1, SHV-12, IMP-26 and DHA-1. MLST analysis distinguished the 53 isolates into 51 STs and only ST414 and ST520 were assigned two isolates of each (2/53). CONCLUSION: The antimicrobial resistance rates were low among 53 E. cloacae bloodstream isolates in the two hospitals. Multiclonality disclosed no evidence on spread of these isolates in Shanghai. The simultaneous presence of ESBL, carbapenemase and pAmpC detected in 2 isolates was firstly reported in Shanghai, which necessitated active ongoing surveillances and consistent prevention and control of E. cloacae.

[Molecular epidemiological study of colistin-only-sensitive strains of multi-drug resistant Acinetobacter baumannii].

OBJECTIVE: To genetically analyze the epidemiology of the colistin-only-sensitive (COS) Acinetobacter baumannii (COS-AB) so as to provide experimental data for controlling COS-AB infection. METHODS: The drug resistance to 14 antibiotics of 136 COS-AB isolates collected in Ruijin Hospital from June 2004 to May 2005 were analyzed. 66 A. baumannii isolates were collected from May to December 2004, of which 33 strains were COS-AB and the other 33 non-COS-AB. Random amplified polymorphic DNA (RAPD) and pulsed-field gel electrophoresis (PFGE) were applied to analyze the homology of these strains. RESULTS: RAPD analysis (with the primers ERIC2 and 272) showed all COS-AB strains as identical, while PFGE analysis showed that these COS-AB were of two closely related genotypes distinctly different from that of the non-COS-AB. The COS-AB strains obtained from the Burns Ward were PFGE B type causing inter-ward outbreak of single clone. And the COS-AB strains obtained from another wards were PFGE BA type causing inter-departmental outbreak, mainly among the departments of surgical system. CONCLUSION: The cross-infection of COS-AB is severe. Strict disinfection and sterilization should be implemented. The epidemiology of COS-AB in environment and patients should be closely monitored. PFGE analysis is a more accurate method in typing A. baumannii.

Molecular Epidemiology of Staphylococcus aureus among Patients with Skin and Soft Tissue Infections in Two Chinese Hospitals.

BACKGROUND: Staphylococcus aureus is one of the predominant causes of skin and soft tissue infections (SSTIs), but limited data were available regarding the characterization of S. aureus from SSTIs patients in Jiangsu Province in China. We aimed to investigate the molecular epidemiology of S. aureus among SSTIs patients in two hospitals of Jiangsu Province. METHODS: Sixty-two patients with SSTIs from two Chinese hospitals in Jiangsu Province were enrolled in this study, and 62 S. aureus isolates were collected from February 2014 to January 2015. S. aureus isolates were characterized by antimicrobial susceptibility testing, toxin gene detection, and molecular typing with sequence type, Staphylococcus protein A gene type, accessory gene regulator (agr) group, and Staphylococcal cassette chromosome mec t ype. RESULTS: Sixteen (25.8%) methicillin-resistant S. aureus (MRSA) isolates were detected, and there was no isolate found resistant to vancomycin, teicoplanin, sulfamethoxazole-trimethoprim, and linezolid. The sei was the toxin gene most frequently found, and no lukS/F-PV-positive isolates were detected among the SSTIs' patients. Molecular analysis revealed that ST398 (10/62, 16.1%; 2 MRSA and 8 methicillin-susceptible S. aureus) to be the dominant clone, followed by ST5 (8/62, 12.9%) and ST7 (8/62, 12.9%). CONCLUSIONS: The livestock ST398 was the most common clone among patients with S. aureus SSTIs in Jiangsu Province, China. Surveillance and further studies on the important livestock ST398 clone in human infections are necessarily requested.

Resistant mechanisms and molecular epidemiology of imipenem-resistant Acinetobacter baumannii.

The aim of the study was to investigate the resistant mechanisms and homology of imipenem-resistant Acinetobacter baumannii (A. baumannii). A total of 46 non-duplicate imipenem­resistant A. baumannii clinical isolates were collected from three tertiary hospitals between July, 2011 and June, 2012. The minimal inhibitory concentrations (MICs) of antimicrobial agents were determined using the agar dilution method. Phenylalanine­arginine ß-naphthylamide was used to detect the presence of the efflux pump-mediated resistant mechanism. Polymerase chain reaction was employed to amplify genes associated with drug resistance, including ß­lactamase genes, efflux pump genes and outer membrane protein gene CarO. A few amplicons were randomly selected and sequenced. Multilocus sequence analysis (MLST) was employed in typing A. baumanni. A. baumannii was resistant to imipenem, simultaneously showing resistance to several other antimicrobials. In addtition, 13 A. baumannii were found to mediate drug resistance through operation of the efflux pump. Of the various drug resistance genes tested, blaOXA­51 was present in 46 isolates, blaOXA­23 gene was present in 44 isolates and blaNDM gene was found in only one strain. Other drug resistant­associated genes, including blaKPC, blaIMP, blaOXA-24, blaOXA­58, blaSHV, blaGIM and blaVIM were not detected. Mutation of adeS and outer membrane protein gene CarO were found in a few of the imipenem­resistant isolates. The MLST analysis revealed that all 46 clinical isolates were clustered into 11 genotypes and the most frequent genotype was ST208. In conclusion, ß­lactamase genes, genes involved in efflux pump and mutation of outer membrane protein encoding gene may be important in mediating imipenem resistance in A. baumannii. Of the 11 different genotypes, ST11 was shared by the majority of A. baumannii, which may be due to horizontal transfer of patients from hospitals.

Antimicrobial Resistance and Molecular Epidemiology of Escherichia coli Causing Bloodstream Infections in Three Hospitals in Shanghai, China.

Escherichia coli (E. coli) is one of the most frequent and lethal causes of bloodstream infections (BSIs). We carried out a retrospective multicenter study on antimicrobial resistance and phylogenetic background of clinical E. coli isolates recovered from bloodstream in three hospitals in Shanghai. E. coli isolates causing BSIs were consecutively collected between Sept 2013 and Sept 2014. Ninety isolates randomly selected (30 from each hospital) were enrolled in the study. Antimicrobial susceptibility testing was performed by disk diffusion. PCR was used to detect antimicrobial resistance genes coding for ß-lactamases (TEM, CTX-M, OXA, etc.), carbapenemases (IMP, VIM, KPC, NDM-1 and OXA-48), and phylogenetic groups. eBURST was applied for analysis of multi-locus sequence typing (MLST). The resistance rates for penicillins, second-generation cephalosporins, fluoroquinolone and tetracyclines were high (>60%). Sixty-one of the 90 (67.8%) strains enrolled produced ESBLs and no carbapenemases were found. Molecular analysis showed that CTX-M-15 (25/61), CTX-M-14 (18/61) and CTX-M-55 (9/61) were the most common ESBLs. Phylogenetic group B2 predominated (43.3%) and exhibited the highest rates of ESBLs production. ST131 (20/90) was the most common sequence type and almost assigned to phylogenetic group B2 (19/20). The following sequence types were ST405 (8/90) and ST69 (5/90). Among 61 ESBL-producers isolates, B2 (26, 42.6%) and ST131 (18, 29.5%) were also the most common phylogenetic group and sequence type. Genetic diversity showed no evidence suggesting a spread of these antimicrobial resistant isolates in the three hospitals. In order to provide more comprehensive and reliable epidemiological information for preventing further dissemination, well-designed and continuous surveillance with more hospitals participating was important.

Risk factors for methicillin-resistant Staphylococcus aureus carriage among residents in 7 nursing homes in Shanghai, China.

BACKGROUND: Nursing home residents are a population at risk for methicillin-resistant Staphylococcus aureus (MRSA) carriage, but few data about MRSA in this setting in Shanghai are available. The aim of this study is to determine the prevalence and risk factors for MRSA carriage in nursing home residents in Shanghai, China. METHODS: Four hundred forty-three residents from 7 nursing homes in Shanghai, China, participated in this study; nasal and axillary swabs were obtained from these residents. Laboratory identification for S aureus and antimicrobial susceptibility testing were performed when isolated. Data, including individual resident characteristics and nursing home characteristics, were collected and analyzed. RESULTS: Of the 443 participating residents, 99 (22.3%) and 45 (10.2%) residents were colonized by S aureus and MRSA, respectively. Previous hospitalization (odds ratio [OR], 2.564; 95% confidence interval [CI], 1.214-5.415; P = .014), presence of an invasive device (OR, 3.455; 95% CI, 1.678-7.113; P = .001), chloramphenicol therapy (OR, 7.672; 95% CI, 1.807-32.580; P = .006), and macrolides therapy (OR, 2.796; 95% CI, 1.056-7.403; P = .038) were independent risk factors for MRSA colonization. Low expenditure per month and less good sanitary condition also increased the risk for MRSA colonization. CONCLUSIONS: Our study suggests that nursing homes are significant reservoirs for MRSA. Implementation of infection control strategies must be given high priority in nursing homes to fight the high prevalence of MRSA, and increased convenience and feasibility should also be realized with these control strategies for MRSA colonization.

Prevalence and Molecular Epidemiology of Staphylococcus aureus among Residents of Seven Nursing Homes in Shanghai.

BACKGROUND: Residents in nursing homes (NHs) always represent potential reservoirs for Staphylococcus aureus and methicillin-resistant S. aureus (MRSA). To our knowledge, there is no epidemiological information up till now that describes the prevalence and molecular characteristics of S. aureus in nursing home residents in Shanghai, China. METHODS: Four hundred and ninety-one unique residents from 7 NHs were enrolled in this study. Specimens were collected among these residents including 491 nasal swabs, 487 axillary swabs and 119 skin swabs. S. aureus isolated and identified from the swabs was characterized according to antimicrobial susceptibility profiling, toxin gene prevalence, and multilocus sequence typing (MLST), spa and SCCmec typing. RESULTS: Among the 491 residents screened, S. aureus was isolated in 109 residents from 90 nasal swabs (90/491, 18.3%), 29 axillary swabs (29/487, 6.0%), and 22 skin swabs (22/119, 18.5%). Sixty-eight MRSA isolates were detected in 52 residents from 41 nasal carriers, 15 axillary carriers and 12 skin carriers. The overall prevalence rate of S. aureus and MRSA colonization was 22.2% and 10.6% respectively. Ten residents presented S. aureus in all three sample types and 12 residents presented S. aureus in two of the three sample types collected. Molecular analysis revealed CC1 (29.1%) to be the dominant clone in this study, followed by CC398 (19.9%), CC188 (13.5%) and CC5 (12.8%). The most common spa type was t127 (22.0%), followed by t14383 (12.8%) and t002 (10.6%). CONCLUSIONS: A high prevalence of S. aureus and MRSA colonization was revealed in nursing home residents in Shanghai. CC1 was the most common clonal complex and t127 was the most common spa type among NH residents. The data provides an important baseline for future surveillance of S. aureus in NHs in Shanghai and other highly urbanized regions in China. Implementation of infection control strategies must be given high priority in NHs to fight such high prevalence of both MRSA and methicillin-susceptible S. aureus (MSSA).