Whole-genome sequencing links cases dispersed in time, place, and person while supporting healthcare worker management in an outbreak of Panton-Valentine leucocidin meticillin-resistant Staphylococcus aureus; and a review of literature.

This is a report on an outbreak of Panton-Valentine leucocidin-producing meticillin-resistant Staphylococcus aureus (PVL-MRSA) in an intensive care unit (ICU) during the COVID-19 pandemic that affected seven patients and a member of staff. Six patients were infected over a period of ten months on ICU by the same strain of PVL-MRSA, and a historic case identified outside of the ICU. All cases were linked to a healthcare worker (HCW) who was colonized with the organism. Failed topical decolonization therapy, without systemic antibiotic therapy, resulted in ongoing transmission and one preventable acquisition of PVL-MRSA. The outbreak identifies the support that may be needed for HCWs implicated in outbreaks. It also demonstrates the role of whole-genome sequencing in identifying dispersed and historic cases related to the outbreak, which in turn aids decision-making in outbreak management and HCW support. This report also includes a review of literature of PVL-MRSA-associated outbreaks in healthcare and highlights the need for review of current national guidance in the management of HCWs' decolonization regimen and return-to-work recommendations in such outbreaks.

Risk factors for meticillin-resistant Staphylococcus aureus (MRSA) carriage in MRSA-exposed household pets.

BACKGROUND: Household pets can carry meticillin-resistant Staphylococcus aureus (MRSA) introduced to the home by their human companions. Specific factors promoting pet carriage of this pathogen have not been fully elucidated. OBJECTIVE: This study evaluated MRSA cultured from pets and the home environment in households where a human infected with MRSA had been identified, and aimed to determine potential risk factors for pet MRSA carriage. MATERIALS AND METHODS: Humans diagnosed with community-associated MRSA (CA-MRSA) skin or soft-tissue infection (SSTI) in the mid-Atlantic United States were identified. One hundred forty-two dogs and cats from 57 affected households were identified of which 134 (94.4%) pets and the household environment were sampled for bacterial culture, PCR confirmation and spa-typing for MRSA strain determination. Samples were obtained 3 months later from 86 pets. RESULTS: At baseline, 12 (9.0%) pets carried MRSA. Potential risk factors associated with carriage included pet bed (environmental) MRSA contamination, flea infestation and prior antimicrobial use in the pet. Pets tended to carry human-adapted MRSA strains and spa-types of MRSA isolates cultured from pets were concordant with strains cultured from the home environment in seven of eight homes (87.5%) at baseline. CONCLUSIONS AND CLINICAL RELEVANCE: Results may inform risk-based veterinary clinical recommendations and provide evidence for selective pet testing as a possible alternative to early removal of pets from the homes of humans infected with MRSA. MRSA contamination of the home environment is likely an important risk factor for pet MRSA carriage, and household interventions should be considered to reduce risk of MRSA carriage in exposed pets.

nanoMLST: accurate multilocus sequence typing using Oxford Nanopore Technologies MinION with a dual-barcode approach to multiplex large numbers of samples.

Multilocus sequence typing (MLST) is one of the most commonly used methods for studying microbial lineage worldwide. However, the traditional MLST process using Sanger sequencing is time-consuming and expensive. We have designed a workflow that simultaneously sequenced seven full-length housekeeping genes of 96 meticillin-resistant Staphylococcus aureus isolates with dual-barcode multiplexing using just a single flow cell of an Oxford Nanopore Technologies MinION system, and then we performed bioinformatic analysis for strain typing. Fifty-one of the isolates comprising 34 sequence types had been characterized using Sanger sequencing. We demonstrate that the allele assignments obtained by our nanopore workflow (nanoMLST, available at https://github.com/jade-nhri/nanoMLST) were identical to those obtained by Sanger sequencing (359/359, with 100 % agreement rate). In addition, we estimate that our multiplex system is able to perform MLST for up to 1000 samples simultaneously; thus, providing a rapid and cost-effective solution for molecular typing.

Perils of the pneumatic tube: how clean are your pods?

Pneumatic tube systems (PTSs) are useful features in hospitals for efficient transport of items but further scrutiny reveals their potential risks. We investigated the extent of contamination of pods, used within the PTS with specific alert organisms, namely meticillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE) and carbapenemase-producing Enterobacterales (CPE). Results revealed contamination with VRE (53%) and MRSA (3%), which were reduced to only 3% (VRE) and 0% (MRSA) following disinfection. However recontamination occurred quickly following use. Our findings indicate that PTS could be an efficient method of transfer of potential pathogens around the hospital.

Mechanisms of pyroptosis induced by meticillin-resistant Staphylococcus aureus in macrophages / 国际药学研究杂志

Objective: To evaluate the effect of meticillin-resistant Staphylococcus aureus(MRSA)on the pyroptosis of bone-marrow derived macrophages(BMDM)and investigate the mechanism of MRSA-induced pyroptosis in macrophages. Methods: The BMDM were triggered by the combination of lipopolysaccharide(LPS, 100 ng/ml)with adenosine-triphosphate(ATP, 3 mmol/L)or nigericin(Ng, 10 mmol/L)or treated with MRSA(multiplicity of infection 200, MOI 200)alone to induce pyroptosis in vitro. The cell morphology examination and lactate dehydrogenase(LDH)assay were applied to evaluate the cytotoxicity. The expression of pro- inflammatory cytokines, the interleukin(IL)- 1β, IL- 6 and tumor-necrosis factor(TNF)-α was detected by ELISA. The cleaved caspase-1 and mature IL-1β in the cells and released into the supernatant were detected by Western blotting. The signal pathway for the induction of pyroptosis by MRSA was investigated via the transfection of lentivirus- mediated short- hairpin RNA(shRNA)into the BMDM. Results: The treatment of BMDM with LPS/ATP, LPS/nigericin or MRSA alone caused cytotoxicity and up-regulated the expression of pro-inflammatory cytokines, IL-1β, IL-6 and TNF-α, as well as the caspase-1 activation and mature Zl-1β (P<0.01). After silencing NLRP3 or NLRC4, the expression of IL-1β induced by MRSA was significantly lessened(P< 0.01). Conclusion: MRSA could induce BMDM pyroptosis probably via activating NLRP3 inflammasome or NLRC4 inflammasome.

Livestock-associated meticillin-resistant Staphylococcus aureus (MRSA) among human MRSA isolates, European Union/European Economic Area countries, 2013.

Currently, surveillance of livestock-associated meticillin-resistant Staphylococcus aureus (LA-MRSA) in humans in Europe is not systematic but mainly event-based. In September 2014, the European Centre for Disease Prevention and Control (ECDC) initiated a questionnaire to collect data on the number of LA-MRSA from human samples (one isolate per patient) from national/regional reference laboratories in European Union/European Economic Area (EU/EEA) countries in 2013. Identification of LA-MRSA as clonal complex (CC) 398 by multilocus sequence typing (MLST) was preferred, although surrogate methods such as spa-typing were also accepted. The questionnaire was returned by 28 laboratories in 27 EU/EEA countries. Overall, LA-MRSA represented 3.9% of 13,756 typed MRSA human isolates, but it represented ≥ 10% in five countries (Belgium, Denmark, Spain, the Netherlands and Slovenia). Seven of the reference laboratories did not type MRSA isolates in 2013. To monitor the dispersion of LA-MRSA and facilitate targeted control measures, we advocate periodic systematic surveys or integrated multi-sectorial surveillance.

The health and economic burden of bloodstream infections caused by antimicrobial-susceptible and non-susceptible Enterobacteriaceae and Staphylococcus aureus in European hospitals, 2010 and 2011: a multicentre retrospective cohort study.

We performed a multicentre retrospective cohort study including 606,649 acute inpatient episodes at 10 European hospitals in 2010 and 2011 to estimate the impact of antimicrobial resistance on hospital mortality, excess length of stay (LOS) and cost. Bloodstream infections (BSI) caused by third-generation cephalosporin-resistant Enterobacteriaceae (3GCRE), meticillin-susceptible (MSSA) and -resistant Staphylococcus aureus (MRSA) increased the daily risk of hospital death (adjusted hazard ratio (HR) = 1.80; 95% confidence interval (CI): 1.34-2.42, HR = 1.81; 95% CI: 1.49-2.20 and HR = 2.42; 95% CI: 1.66-3.51, respectively) and prolonged LOS (9.3 days; 95% CI: 9.2-9.4, 11.5 days; 95% CI: 11.5-11.6 and 13.3 days; 95% CI: 13.2-13.4, respectively). BSI with third-generation cephalosporin-susceptible Enterobacteriaceae (3GCSE) significantly increased LOS (5.9 days; 95% CI: 5.8-5.9) but not hazard of death (1.16; 95% CI: 0.98-1.36). 3GCRE significantly increased the hazard of death (1.63; 95% CI: 1.13-2.35), excess LOS (4.9 days; 95% CI: 1.1-8.7) and cost compared with susceptible strains, whereas meticillin resistance did not. The annual cost of 3GCRE BSI was higher than of MRSA BSI. While BSI with S. aureus had greater impact on mortality, excess LOS and cost than Enterobacteriaceae per infection, the impact of antimicrobial resistance was greater for Enterobacteriaceae.

Carriage of multidrug-resistant organisms in a tertiary university hospital in Albania-a point prevalence survey.

BACKGROUND: Antimicrobial resistance has been recognised as a serious global Public Health problem. Prevalence of Multiple-Drug-Resistant (MDR) organism carriage in Albania is largely unknown since no national surveillance system is in place and few publications are accessible in the literature. METHODS: A 1-day point-prevalence-survey (PPS) screening for nasal methicillin-resistant Staphylococcus aureus (MRSA) and rectal MDR Gram-negative carriage was carried out at the high-dependency wards in the country's only tertiary care hospital, in Tirana. RESULTS: A total of 106 nasal and 104 rectal swabs were collected. 14.2 % of patients (95 % Confidence Interval [95 CI]: 8.1-22.3 %) were MRSA nasal carriers. Resistance to aminoglycosides and fluoroquinolones was common in these isolates (≥80 %) but no resistance was identified against glycopeptides, nitrofurantoin and the relatively newer agents, tigecycline and linezolid. Fifty Enterobacteriaceae isolates were cultivated from 33 of 104 screened patients (31.7 % [95 CI: 22.9-41.6 % 95 CI]). The prevalence of Extended Spectrum Beta-Lactamase (ESBL) production in Enterobacteriaceae was 41.3 % (95 CI: 31.8-51.4 %). The two more commonly isolated Enterobacteriaceae were E. coli ([n = 28], 24 ESBL positive; 1 AmpC positive and 3 without an identified mechanism of resistance) and Klebsiella pneumoniae ([n = 13], all ESBL positive; 1 also AmpC and metallo-ß-lactamase (MBL) positive). Susceptibility to carbapenems (≥98 %), fosfomycin (90 %) and amikacin (70 + 20 % intermediate) was high but a high level of resistance to all other agents tested was noted. Non-fermenting Gram-negative bacilli were less commonly isolated {22 isolates: Acinetobacter baumannii (9); Pseudomonas aeruginosa (8) and Stenotrophomonas maltophilia (5)}. CONCLUSION: Although a significant rate of MRSA carriage was identified, the main resistance challenge in Albania appears to be linked with Gram-negative organisms, particularly ESBL in Enterobacteriaceae.

Tigecycline antimicrobial activity tested against clinical bacteria from Latin American medical centres: results from SENTRY Antimicrobial Surveillance Program (2011-2014).

Bacterial organisms (n = 13,494) were consecutively collected in 2011-2014 from 21 Latin American medical centres (11 nations). Antimicrobial susceptibility was determined by broth microdilution at a central laboratory. Tigecycline was very active against Gram-positive organisms, with MIC50/90 values of 0.06/0.06 µg/mL for Staphylococcus aureus (n = 2878), 0.06/0.12 µg/mL for coagulase-negative staphylococci (n = 880), 0.06/0.06 µg/mL for enterococci (n = 708) and ≤0.03/≤0.03-0.06 µg/mL for streptococci (n = 1352). All Gram-positive species exhibited 100.0% susceptibility (FDA and/or EUCAST criteria), except for Streptococcus pneumoniae (99.8% susceptible). The S. aureus oxacillin resistance rate varied from 28.0% (Brazil) to 55.0% (Argentina), and the overall vancomycin resistance rate was 15.5% (Enterococcus faecium, 50.3%; and Enterococcus faecalis, 2.3%). The E. faecium vancomycin resistance rate varied from a low (26.3%) in Argentina to a high (71.7%) in Brazil. Against Enterobacteriaceae (n = 4543), tigecycline MIC50/90 values were 0.25/1 µg/mL; 98.3% and 94.2% of strains were considered susceptible according to FDA and EUCAST breakpoints, respectively. Overall, 37.7% and 57.3% of Escherichia coli and Klebsiella pneumoniae exhibited the CLSI ESBL screening phenotype. The highest CLSI ESBL screening phenotype rates among E. coli and Klebsiella spp. strains were observed for isolates collected from Mexico (69.9%) and Chile (69.9%), respectively. Occurrence of carbapenem-resistant Enterobacteriaceae was substantially higher in Brazil (9.0%) and Argentina (6.3%) compared with Chile and Mexico (0.4-0.7%). Tigecycline was also active against Acinetobacter spp. (MIC50/90, 1/2 µg/mL; 92.3/72.1% inhibited at ≤2/≤1 µg/mL) and Stenotrophomonas maltophilia (MIC50/90, 0.5/2 µg/mL; 91.5/83.0% inhibited at ≤2/≤1 µg/mL).

Nano-TiO2-based photocatalytic disinfection of environmental surfaces contaminated by meticillin-resistant Staphylococcus aureus.

BACKGROUND: Traditional cleaning and disinfection methods are inefficient for complete decontamination of hospital surfaces from meticillin-resistant Staphylococcus aureus (MRSA). Additional methods, such as nano-TiO2-based photocatalytic disinfection (PCD), could be helpful. AIM: To evaluate anti-MRSA activity of PCD on polyvinyl chloride (PVC) surfaces in natural-like conditions. METHODS: Two identical PVC surfaces were used, and nano-TiO2 was incorporated into one of them. The surfaces were contaminated with MRSA isolated from hospitalized patients using a mist sprayer to simulate the mode of environmental contamination caused by a carrier. MRSA cell density was assessed before contamination until 180min after contamination using Rodac plates. The differences between test and control surfaces in terms of MRSA density and log MRSA density reduction were assessed using parametric and non-parametric statistical tests. Five strains were tested, and each strain was tested five times. FINDINGS: The highest median MRSA densities [46.3 and 43.1 colony-forming units (cfu)/cm(2) for control and test surfaces, respectively] were detected 45min after contamination. Median MRSA densities 180min after contamination were 10.1 and 0.7cfu/cm(2) for control and test surfaces, respectively (P<0.01). Log MRSA density reduction attributable to PCD was 1.16logcfu/cm(2), corresponding to 93% reduction of the baseline MRSA contamination. CONCLUSIONS: The disinfectant activity remained stable throughout the 25 testing occasions, despite between-test cleaning and disinfection. The anti-MRSA activity of PCD was compatible with the benchmark for surface hygiene in hospitals (<1cfu/cm(2)), but required 3h of exposure to photocatalysis. Thus, PCD could be considered for non-clinical surfaces. However, for clinical surfaces, PCD should be regarded as supplemental to conventional decontamination procedures, rather than an alternative.

Incidence of invasive meticillin-resistant Staphylococcus aureus infections in Germany, 2010 to 2014.

Voluntary surveillance systems in Germany suggest a recent decline in the incidence of infections (subsequent to at least 2010) with meticillin-resistant Staphylococcus aureus (MRSA) from various types of specimens and settings. We asked whether this decline is reflected by data from the mandatory national surveillance system for invasive MRSA infections. Our analysis is based on the population in Germany in 2010 to 2014. Cases were identified from passive reporting by microbiological laboratories of the diagnosis of MRSA from blood culture or cerebrospinal fluid. Respective clinical data were subsequently added to the notification. We calculated risk ratios (RR) between consecutive years, stratifying cases by sex, age and federal state of residence. The national incidence increased from 4.6 episodes per 100,000 persons in 2010 to 5.6 in 2012 (2011 vs 2010: RR: 1.13, 95% confidence interval (CI): 1.08-1.18; 2012 vs 2011: RR: 1.08, 95% CI: 1.04-1.13). It stagnated at 5.4 per 100,000 in 2013 (RR: 0.97, 95% CI: 0.93-1.01) before declining to 4.8 in 2014 (RR: 0.88, 95% CI: 0.84-0.91). This trend was observed in most, but not all federal states and strata of sex and age groups. Only 204 of 20,679 (1%) episodes of infection were notified as belonging to an outbreak. Our analysis corroborates previous findings that the incidence of invasive MRSA infections in Germany may be declining.

Meticillin-resistant Staphylococcus aureus CC398 is an increasing cause of disease in people with no livestock contact in Denmark, 1999 to 2011.

Livestock constitutes a potential reservoir of meticillin-resistant Staphylococcus aureus isolates belonging to a recently derived lineage within clonal complex 398 (MRSA CC398-IIa). Since its discovery in the early 2000s, this lineage has become a major cause of human disease in Europe, posing a serious public health challenge in countries with intensive livestock production. To retrace the history of human colonisation and infection with MRSA CC398-IIa in Denmark, we conducted a nationwide, retrospective study of MRSA isolates collected from 1999 to 2011. Among 7,429 MRSA isolates screened, we identified 416 MRSA CC398-IIa isolates. Of these, 148 were from people with infections, including 51 from patients reporting no livestock exposure. The first cases of MRSA CC398-IIa infection in Denmark occurred in 2004. Subsequently, the incidence of MRSA CC398-IIa infection showed a linear annual increase of 66% from 2004 to 2011 (from 0.09 to 1.1 per 100,000 person-years). There were clear temporal and spatial relationships between MRSA CC398-IIa-infected patients with and without livestock exposure. These findings suggest substantial dissemination of MRSA CC398-IIa from livestock or livestock workers into the Danish community and underscore the need for strategies to control its spread both on and off the farm.

Review of meta-analyses of vancomycin compared with new treatments for Gram-positive skin and soft-tissue infections: Are we any clearer?

Vancomycin has been considered the standard of care for treatment of Gram-positive skin and soft-tissue infections (SSTIs). Its value has been questioned over the last decade owing to well acknowledged limitations in efficacy and tolerability and the emergence of newer meticillin-resistant Staphylococcus aureus (MRSA)-active antibacterial agents. However, no single agent has shown better results versus vancomycin in SSTI trials. The aim of this review was to identify and summarise data from meta-analyses (MAs) for the treatment of Gram-positive and MRSA SSTIs. A systematic search identified 21 published MAs examining the use of newer antibiotics and vancomycin in SSTIs. In terms of clinical and microbiological efficacy, linezolid (in Gram-positive and MRSA SSTIs) and telavancin (in MRSA SSTIs) were shown to be more effective than vancomycin. The safety of newer antimicrobials in general was comparable with vancomycin, except for telavancin, which was associated with more severe adverse events (AEs), and tigecycline owing to an all-cause mortality imbalance observed in all infections but not confirmed in SSTIs. Specific AEs were related to the use of newer agents, such as nephrotoxicity for telavancin, creatine phosphokinase elevations for daptomycin, and thrombocytopenia with linezolid. Some evidence suggests that daptomycin could be associated with reduced treatment duration, and linezolid with reduced length of intravenous treatment and hospital length of stay compared with vancomycin. Considering the limitations of this type of research and the comparative efficacy results demonstrated in head-to-head randomised controlled trials, data are still not sufficient to support the widespread use of new agents over vancomycin.

Epidemiology of meticillin-resistant Staphylococcus aureus bloodstream infections in Alberta, Canada.

Most studies of meticillin-resistant Staphylococcus aureus (MRSA) bloodstream infection (BSI) reflect a convenience sample from a single hospital or a small group of hospitals. From April 2011 to March 2013, cases of MRSA BSI diagnosed in all hospitals in Alberta, Canada were captured prospectively. Isolates were spa typed. In total, there were 299 cases of MRSA BSI, equating to 3.95 cases per 100,000 population. Community-acquired BSI accounted for 66.9% of cases, and 33.1% of cases were hospital acquired. Cases were predominantly seen in tertiary care (36.4%) and large urban hospitals (34.3%), but were also common in regional and rural hospitals. Paediatric hospitals had very few cases (3.0%). Two clones, CMRSA 10 (USA 300; 40.2%) and CMRSA 2 (USA 100/800; 38.0%), predominated.

Inguinal skin colonization with multidrug-resistant bacteria among residents of elderly care facilities: frequency, persistence, molecular analysis and clinical impact.

Frequency, persistence and molecular characteristics of multidrug resistant bacteria colonizing inhabitants of long term care facilities are topics of current concern. We performed a point-prevalence survey of 402 residents in 7 elderly care facilities in Berlin, Germany. Inguinal swabs were analyzed for the presence of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococci (VRE), and multidrug-resistant gram-negative bacteria. Three and six months following the initial investigation, all colonized residents were sampled again and the occurrence of intercurrent infections, hospital admissions and use of antimicrobials were registered. Genetic relatedness of the bacteria was investigated using multi-locus sequence typing (MLST), spa-typing and SmaI/XbaI-macrorestriction analysis. 33 (8.2%) residents were skin-colonized with multidrug-resistant bacteria. MRSA were found in 19 (4.7%) and ESBL-producing Enterobacteriaceae in 16 residents (3.98%). Independent risk factors for colonization with multidrug-resistant bacteria were a high level of care and the presence of chronic wounds. A large proportion of the observed bacteria persisted up to six months and showed a high degree of inter-individual diversity. Outcome analysis revealed that infections tend to occur slightly more often in residents colonized by multiresistant pathogens. We assume that a perceptible population of residents in nursing homes is at risk for individual colonization with multidrug-resistant bacteria as well as healthcare associated infections.

Colonización por Staphylococcus aureus resistentea meticilina en las manos de individuosde la comunidad / Hand colonization by methicillin-resistant Staphylococcus aureus (MRSA) in the community

En la última década han sido cada vez más frecuentes los informes de infecciones causadas porcepas de Staphylococcus aureus resistente a meticilina asociadas a la comunidad (CA-MRSA,por Community-associated methicillin-resistant S. aureus). La colonización juega un papelimportante en la epidemiología de tales infecciones. Sin embargo, los estudios de colonizaciónse han centrado principalmente en el ambiente hospitalario y se han hecho muy pocos en lacomunidad. En este trabajo se investigó la frecuencia de colonización por S. aureus en generaly por MRSA en las manos de individuos de la población general no relacionados con el área dela salud, empleando métodos fenotípicos y moleculares. Se obtuvieron mediante hisopado 800muestras de las manos de otros tantos individuos. Se halló colonización por Staphylococcusaureus en 65 muestras (8,1%) y por MRSA en 5 (0,63%). Las 5 cepas de MRSA presentaban elcasete cromosómico mec (SCCmec) de los tipos IV o V, típicamente relacionados con CA-MRSA.Nuestro trabajo evidenció la colonización de las manos por MRSA en individuos de la comunidad,lo cual constituye un importante factor de riesgo, no solo por su asociación con el desarrolloulterior de infecciones, sino también por el potencial de diseminar este microorganismo a lapoblación general.

Community-associated methicillin-resistant Staphylococcus aureus infections (CA-MRSA) havebeen reported with increasing frequency during the past decade. Colonization plays an importantrole in the epidemiology of such infections. However, colonization studies have focused mostlyon hospital settings and only a few have been carried out in communities. This was a study of thefrequency of hand colonization by S. aureus in generaland by CA-MRSA, by means of phenotypical andmolecular methods, in 800 adults from the communitywho had no relationship with the health area.Staphylococcus aureus colonization was found in 65individuals (8.1%) and MRSA was present in 5 (0.63%).The 5 MRSA strains were found to have mecchromosomic cassettes (SCCmec) of either type IV orV, typical of CA-MRSA. Our study provides evidence ofCA-MRSA colonization in the hands of individuals fromthe community. This constitutes an important riskfactor, not only by its association with subsequentinfections, but also for the risk of dissemination of thismicroorganism to the general population.

Drug-resistant Gene and Disinfectant-resistant Gene for MRSA / 中华医院感染学杂志

OBJECTIVE To study the drug resistance,drug-resistant genes and(disinfectant)-resistant genes of(MRS)A.METHODS The drug resistance and mecA gene of the ?-lactamase and aac(6′)/aph(2″),aph(3′)-Ⅲ,ant(4′,4″) genes of aminoglycoside and qac(A/B) disinfectant-resistant genes were(detected) in 47 strains of MRSA.(RESULTS) In all 47 strains of MRSA,46 MRSA isolates were mecA positive,39 MRSA isolates were aac(6′)/aph(2″) positive,30 MRSA isolates were aph(3′)-Ⅲ positive,6 MRSA isolates were ant(4′,4″) positive,and 19 MRSA isolates were qac(A/B) positive.CONCLUSIONS MRSA is multiple-drug resistant.The main resistant mechanisms of MRSA to aminoglycosides and disinfectant are related to the drug-resistant genes of aminoglycoside and disinfectant-resistant genes.Clinic physician must pay attention to the diagnosis and(therapy) of MRSA,and control the hospital infection.

Drug-resistance and Gene erm Existing in Meticillin-resistant Staphylococcus aureus / 中华医院感染学杂志

OBJECTIVE To investigate the resistance of meticillin-resistant Staphylococcus aureus(MRSA) and the occurrence of gene erm.METHODS ATB Staph and microdilute tests were performed to detect the susceptibility to 15 kinds of antibiotics in 50 strains of the S.aureus(SAU).Gene erm of these strains was detected by polymerase chain reaction(PCR).RESULTS There were no strains resistant to vancomycin,teicoplanin,fusidic acid and quinupristin-dalfopristin in 42 strains of MRSA detected.There were no strains sensitive to penicillin,oxacillin,gentamicin,tetracycline,ciprofloxacin and levofloxacin.Thirty-five strains habored gene erm in 42 strains of MRSA.The positive rate of gene erm was 83.3%.CONCLUSIONS The multiple-resistance of the MRSA is a serious issue.The resistance to erythromycin in MRSA is mediated by gene erm which encodes the methylase and changes the target site of drug action.

Drug-resistant Gene and Disinfectant-resistant Gene in MRSA / 中华医院感染学杂志

OBJECTIVE To study the drug resistance,drug-resistant genes and disinfectant-resistant genes of clinical MRSA isolates.METHODS The sensitivity to penicillin and other 15 antibacterial agents was detected in 56 strains of MRSA by K-B paper disk diffusion.The mecA gene of the ?-lactamase and disinfectant-resistant genes qac(A/B)were detected by PCR.RESULTS All of the 56 strains of MRSA were sensitive to vancomycin and teicoplanin.Drug resistant rate of sulfamethoxzole/trimethoprim,nitrofurantoin,rifampin,tetracycline,levofloxacin,clindamycin and azithromycin were 17.9%,23.2%,82.1%,87.5%,89.3%,92.9% and 96.4%,respectively.All of the 56 strains were resistant to erythromycin,gentamicin,amikacin,penicillin,ampicillin/sulbactam,cefoxitin and ampicillin.In all 56 strains of MRSA,54(96.4%)MRSA isolates were mecA positive and 31(55.4%)MRSA isolates were qac(A/B)positive.CONCLUSIONS Clinically isolated MRSAs is multi-drug-resistant and the qac(A/B)positive rate is very high.

MRSA Infection in ICU:Investigation and Analysis of Nine Patients / 中华医院感染学杂志

OBJECTIVE To investigate and analyze the reasons of nosocomial infection(NI) in patients in intensive care unit( ICU),to find effective countermeasures for preventing NI and reducing the incidence rate of NI in ICU,and to enhance the management of ICU.METHODS All data of patients who suffered MRSA in ICU from Dec 2005 to Feb 2006,were analyzed by prospective monitoring and retrospective studies.RESULTS The nine patients were with lower respiratory tract.All were infected by the same MRSA.The same MRSA strain was found from hand,mouth and nose among the treating doctor and nurses based on the sample-analysis.CONCLUSIONS The incidence rate of NI in ICU is much higher than that in other departments.Risk factors depend on the severity of underlying diseases,invasive procedure,the quality of disinfection and sterilization,the incorrect use of the antibiotic,and patients′ immunity status especially among elderly.The key way to reduce incidence rate of NI is to take comprehensive measures and strengthen the antibiotic management.