烧伤患者创面金黄色葡萄球菌感染的耐药性与流行病学分析

目的了解烧伤患者创面感染金黄色葡萄球菌的耐药性及流行状况。方法收集烧伤病房2007年10-12月之间63例患者创面分离的金黄色葡萄球菌63株,纸片扩散法检测其对10种抗生素的耐药率、随机引物扩增PCR(RAPD)检测其流行状况。结果63株金黄色葡萄球菌对氨苄西林的耐药率最高,没有检测到对万古霉素耐药的金黄色葡萄球菌。56株金黄色葡萄球菌为耐甲氧西林的金黄色葡萄球菌(MRSA),7株为甲氧西林敏感的葡萄球菌(MSSA),除万古霉素外,MRSA对其他9种抗生素的耐药率比MSSA高16.1%～100%,63株金黄色葡萄球菌经RAPD分型分为7个基因型,其中Ⅰ、Ⅱ、Ⅲ、Ⅳ、ⅤⅥ、Ⅶ型分别占12.7%、17.5%、9.5%、39.7%、9.5%、6.3%、4.8%。结论烧伤患者创面金黄色葡萄球菌分离株对多种抗生素具有高耐药性,以MRSA感染为主,基因型以Ⅳ型为主。     

Epidemiology and clonality of methicillin-resistant and methicillin-susceptible Staphylococcus aureus causing bacteremia in a tertiary-care hospital in Spain.

OBJECTIVES: To describe the relative proportions of nosocomial and community-onset Staphylococcus aureus bacteremia at our institution and the epidemiologic characteristics and clonal diversity of S. aureus isolates, as determined by pulsed-field gel electrophoresis (PFGE) and antimicrobial resistance patterns. DESIGN: Retrospective cohort study of all cases of S. aureus bacteremia between October 2001 and October 2002. SETTING: A 1300-bed, tertiary-care hospital. RESULTS: One hundred sixty-two unique episodes of S. aureus bacteremia were identified. Forty-three cases (26.5%) were caused by methicillin-resistant S. aureus (MRSA). Most cases of S. aureus bacteremia, whether MRSA or methicillin susceptible (MSSA), were nosocomial in origin (77.2%) or were otherwise associated with the healthcare system (16%). Only 11 (6.8%) of the cases (all MSSA) were strictly community acquired. Thirty-five unique macrorestriction patterns were identified among the 154 isolates that were typed by PFGE. Four major genotypes were defined among the isolates of MRSA, with 36 (85.7%) represented by a single PFGE type. Of the isolates within this major clone, all (100%) were ciprofloxacin resistant and 77.8% were erythromycin resistant. In contrast, the 112 isolates of MSSA comprised 31 different PFGE types, 3 of which represented 42.9% of all MSSA isolates and were associated with both nosocomial and community-onset bacteremia. CONCLUSIONS: Most cases of S. aureus bacteremia in our healthcare region are nosocomial in origin or are acquired through contact with the healthcare system and are thus potentially preventable. To preclude dissemination of pathogenic clones, it is therefore necessary to redouble preventive measures in both the hospital and the community.     

Costs and outcomes among hemodialysis-dependent patients with methicillin-resistant or methicillin-susceptible Staphylococcus aureus bacteremia.

OBJECTIVE: Comorbid conditions have complicated previous analyses of the consequences of methicillin resistance for costs and outcomes of Staphylococcus aureus bacteremia. We compared costs and outcomes of methicillin resistance in patients with S. aureus bacteremia and a single chronic condition. DESIGN, SETTING, AND PATIENTS: We conducted a prospective cohort study of hemodialysis-dependent patients with end-stage renal disease and S. aureus bacteremia hospitalized between July 1996 and August 2001. We used propensity scores to reduce bias when comparing patients with methicillin-resistant (MRSA) and methicillin-susceptible (MSSA) S. aureus bacteremia. Outcome measures were resource use, direct medical costs, and clinical outcomes at 12 weeks after initial hospitalization. RESULTS: Fifty-four patients (37.8%) had MRSA and 89 patients (62.2%) had MSSA. Compared with patients with MSSA bacteremia, patients with MRSA bacteremia were more likely to have acquired the infection while hospitalized for another condition (27.8% vs 12.4%; P = .02). To attribute all inpatient costs to S. aureus bacteremia, we limited the analysis to 105 patients admitted for suspected S. aureus bacteremia from a community setting. Adjusted costs were higher for MRSA bacteremia for the initial hospitalization (21,251 dollars vs 13,978 dollars; P = .012) and after 12 weeks (25,518 dollars vs 17,354 dollars; P = .015). At 12 weeks, patients with MRSA bacteremia were more likely to die (adjusted odds ratio, 5.4; 95% confidence interval, 1.5 to 18.7) than were patients with MSSA bacteremia. CONCLUSIONS: Community-dwelling, hemodialysis-dependent patients hospitalized with MRSA bacteremia face a higher mortality risk, longer hospital stays, and higher inpatient costs than do patients with MSSA bacteremia.     

新生儿病房分离金黄色葡萄球菌耐药性及耐消毒剂基因检测

目的了解新生儿病房送检标本中金黄色葡萄球菌的耐药谱及耐消毒剂基因携带情况。方法收集2013年1—12月某院新生儿病房住院新生儿送检标本分离的金黄色葡萄球菌,采用VITEK2 Compact细菌鉴定分析系统进行细菌鉴定及药敏试验,采用聚合酶链反应(PCR)检测耐消毒剂qacA/B基因。结果新生儿科送检标本中共分离225株金黄色葡萄球菌,主要来源于呼吸道(72.44%)和脐部分泌物(14.33%);耐甲氧西林金黄色葡萄球菌(MRSA)检出率为8.89%(20株);耐药监测中,MRSA的耐药率普遍高于甲氧西林敏感金黄色葡萄球菌(MSSA)。左氧氟沙星、莫西沙星、替加环素、万古霉素、利奈唑胺及呋喃妥因对所有金黄色葡萄球菌均显示出良好的抗菌活性,敏感率均为100%。携带qacA/B基因的金黄色葡萄球菌有21株,阳性率为9.33%,其中MRSA3株(15.00%),MSSA18株(8.78%)。结论新生儿病房分离的MRSA耐药严重,同时携带qacA/B基因,应引起临床重视。     

Changing epidemiology of community-onset methicillin-resistant Staphylococcus aureus bacteremia.

OBJECTIVES: To review cases of community-onset Staphylococcus aureus bacteremia and to evaluate whether the risk factors and epidemiology of methicillin-resistant S. aureus (MRSA) bacteremia have changed from early reports. DESIGN: Retrospective case-comparison study of community-onset MRSA (n = 26) and methicillin-susceptible S. aureus (MSSA) (n = 26) bacteremias at our institution. SETTING: A 600-bed urban academic medical center. PATIENTS: Twenty-six patients with community-onset MRSA bacteremia were compared with 26 patients with community-onset MSSA bacteremia. Molecular analysis was performed on S. aureus isolates from the 26 MRSA cases as well as from 13 cases of community-onset S. aureus bacteremia from 1980 and 9 cases of nosocomial S. aureus bacteremia from 2001. RESULTS: The two groups were similar except that patients with MRSA bacteremia were more likely to have presented from a long-term-care facility (26.9% vs 4%; P = .05) and to have had multiple admissions within the preceding year (46% vs 15%; P = .03). Clamped homogeneous electric fields analysis of MRSA isolates from 1982 revealed predominantly that one clone was the epidemic strain, whereas there were 14 unique strains among current community-onset isolates. Among current nosocomial isolates, 3 patterns were identified, all of which were present in the community-onset cases. CONCLUSIONS: Previously described risk factors for MRSA acquisition may not be helpful in predicting disease due to the polyclonal spread of MRSA in the community. Unlike early outbreaks of MRSA in patients presenting from the community, current acquisition appears to be polyclonal and is usually related to contact with the healthcare system.     

Staphylococcus aureus with reduced susceptibility to vancomycin--Illinois, 1999

Staphylococcus aureus is one of the most common causes of hospital- and community-acquired infections. Nosocomial methicillin-resistant S. aureus (MRSA) infections have become common, and cases of community-acquired MRSA infections also have occurred. Since 1996, vancomycin-intermediate S. aureus (VISA; vancomycin minimum inhibitory concentration [MIC = 8-16 microg/mL) has been identified in Europe, Asia, and the United States. The emergence of reduced vancomycin susceptibility in S. aureus increases the possibility that some strains will become fully resistant and that available antimicrobial agents will become ineffective for treating infections caused by such strains. This report describes the fourth case of confirmed VISA from a patient in the United States.     

The impact of methicillin resistance in Staphylococcus aureus bacteremia on patient outcomes: mortality, length of stay, and hospital charges.

OBJECTIVE: To evaluate the impact of methicillin resistance in Staphylococcus aureus on mortality, length of hospitalization, and hospital charges. DESIGN: A cohort study of patients admitted to the hospital between July 1, 1997, and June 1, 2000, who had clinically significant S. aureus bloodstream infections. SETTING: A 630-bed, urban, tertiary-care teaching hospital in Boston, Massachusetts. PATIENTS: Three hundred forty-eight patients with S. aureus bacteremia were studied; 96 patients had methicillin-resistant S. aureus (MRSA). Patients with methicillin-susceptible S. aureus (MSSA) and MRSA were similar regarding gender, percentage of nosocomial acquisition, length of hospitalization, ICU admission, and surgery before S. aureus bacteremia. They differed regarding age, comorbidities, and illness severity score. RESULTS: Similar numbers of MRSA and MSSA patients died (22.9% vs 19.8%; P = .53). Both the median length of hospitalization after S. aureus bacteremia for patients who survived and the median hospital charges after S. aureus bacteremia were significantly increased in MRSA patients (7 vs 9 days, P = .045; 19,212 dollars vs 26,424 dollars, P = .008). After multivariable analysis, compared with MSSA bacteremia, MRSA bacteremia remained associated with increased length of hospitalization (1.29 fold; P = .016) and hospital charges (1.36 fold; P = .017). MRSA bacteremia had a median attributable length of stay of 2 days and a median attributable hospital charge of 6916 dollars. CONCLUSION: Methicillin resistance in S. aureus bacteremia is associated with significant increases in length of hospitalization and hospital charges.     

临床分离金黄色葡萄球菌的耐药特点和MRSA分子分型

目的研究耐甲氧西林金黄色葡萄球菌(MRSA)的耐药性及其基因分型。方法收集某院2014年1月—2015年11月检出的非重复金黄色葡萄球菌967株,检测其药敏结果及mecA抗性基因、杀白细胞素(PVL)基因;MRSA菌株经多重PCR进行葡萄球菌盒式染色体mec(SCCmec)分型、多位点序列分型(MLST)、金黄色葡萄球菌蛋白A基因(spa)分型、金黄色葡萄球菌附属因子调节子(agr)分型。结果 967株金黄色葡萄球菌共检出210株MRSA,MRSA检出率为21.72%;痰标本MRSA检出率高于皮肤软组织标本(68.09%vs 11.83%,P0.05);金黄色葡萄球菌中未发现对万古霉素和利奈唑胺耐药菌株,MRSA对庆大霉素、四环素、红霉素、克林霉素、左氧氟沙星、环丙沙星、莫西沙星、呋喃妥因、利福平的敏感率均低于MSSA,差异均有统计学意义(均P0.05);MRSA对复方磺胺甲口恶唑的敏感率高于MSSA,差异有统计学意义(P0.05)。皮肤软组织分离的MRSA对庆大霉素、左氧氟沙星、环丙沙星、莫西沙星、利福平的敏感率为86.90%~95.24%,而痰分离的MRSA仅为1.56%~15.63%。967株金黄色葡萄球菌检测出210株携带mecA基因,10株携带PVL基因,210株MRSA中有8株未分型,占3.81%。MLST主要以ST239(177株)为主;SCCmec分型主要以Ⅲ型(177株)为主;spa分型主要以t 030(177株)为主;agr分型主要以Ⅰ型(196株)为主。结论该院MRSA菌株主要流行克隆ST239-MRSA-SCCmecⅢ-t030,耐药形势严峻,应加强医院内耐药菌株的监测。     

Current aspects of Salmonella bacteremia cases in the Ibrahima Diop Mar Infectious Diseases clinic, Fann National Hospital Center (Senegal)

OBJECTIVE: The aim of this study was to describe epidemiological, clinical and bacteriological aspects of Salmonella bacteremia in the Fann university hospital infectious diseases clinic. PATIENTS AND METHOD: This study was carried out on data recorded between January 1, 1996 and December 31, 2003. The strains were identified according to biochemical (API 20E, BioMérieux) and antigenic features. Their susceptibility to antibiotic drugs was tested by antibiogram. Research of strains secreting of an extended-spectrum betalactamase was performed. RESULTS: Fifty five cases of Salmonella bacteremia were recorded as follows: S.Typhi bacteremia (32 cases), S. Paratyphi C bacteremia (4 cases), S. typhimurium bacteremia (9 cases), S. enteritidis bacteremia (32 cases) and S. spp bacteremia (8 cases). All the strains were susceptible to ciprofloxacin, ceftriaxone, aztreonam, amoxicillin+clavulanic acid and 90 % of them were susceptible to cotrimoxazole. Bacteremia occurred in 50 HIV infected patients (49%). Salmonella other than Typhi bacteremia were more often present in patients with HIV (81% vs 36% in patients without HIV infection) (P = 0.00001). The lethality rate was 42%. This rate was higher in patients with HIV (56 vs 23% in patients without infection) (P = 0.002). CONCLUSION: The lethality rate of Salmonella bacteremia is high, especially in AIDS patients. Therefore, priority must be given to prevention and chemoprophylaxis with cotrimoxazole should be a good way to reduce the incidence of bacteremia in AIDS patients.     

Methicillin-resistant Staphylococcus aureus in U.S. hospitals, 1975-1991.

OBJECTIVES: Analyze changes that have occurred among U.S. hospitals over a 17-year period, 1975 through 1991, in the percentage of Staphylococcus aureus resistant to beta-lactam antibiotics and associated with nosocomial infections. DESIGN: Retrospective review. The percentage of methicillin-resistant S aureus (MRSA) was defined as the number of S aureus isolates resistant to either methicillin, oxacillin, or nafcillin divided by the total number of S aureus isolates for which methicillin, oxacillin, or nafcillin susceptibility test results were reported to the National Nosocomial Infections Surveillance (NNIS) System. SETTING: NNIS System hospitals. RESULTS: Of the 66,132 S aureus isolates that were tested for susceptibility to methicillin, oxacillin, or nafcillin during 1975 through 1991, 6,986 (11%) were resistant to methicillin, oxacillin, or nafcillin. The percentage MRSA among all hospitals rose from 2.4% in 1975 to 29% in 1991, but the rate of increase differed significantly among 3 bed-size categories: < 200 beds, 200 to 499 beds, and > or = 500 beds. In 1991, for hospitals with < 200 beds, 14.9% of S aureus isolates were MRSA; for hospitals with 200 to 499 beds, 20.3% were MRSA; and for hospitals with > or = 500 beds, 38.3% were MRSA. The percentage MRSA in each of the bed-size categories rose above 5% at different times: in 1983, for hospitals with > or = 500 beds; in 1985, for hospitals with 200 to 499 beds; and in 1987, for hospitals with < 200 beds. CONCLUSIONS: This study suggests that hospitals of all sizes are facing the problem of MRSA, the problem appears to be increasing regardless of hospital size, and control measures advocated for MRSA appear to require re-evaluation. Further study of MRSA in hospitals would benefit our understanding of this costly pathogen.     

Antimicrobial susceptibility of Staphylococcus aureus and characterization of methicillin-resistant Staphylococcus aureus isolated from bovine mastitis in Korea

A total of 402 Staphylococcus aureus isolates from bovine mastitis milk collected during 2003-2009 in Korea were tested for susceptibility to 20 antimicrobial agents. All S. aureus isolates were susceptible to 11 of 20 antimicrobials tested; no resistance was observed against pirlimycin, telithromycin, novobiocin, penicillin/novobiocin, quinupristin/dalfopristin, clindamycin, rifampin, ciprofloxacin, trimethprim/sulfamethoxazol, vancomycin, and linezolid. Over 66% of the S. aureus isolates were resistant to penicillin. Resistance was also seen for gentamicin (11.9%), erythromycin (7.7%), methicillin (oxacillin and cefoxitin, 6.2%), and tetracycline (4.2%). No noticeable change was observed in penicillin, gentamicin, and erythromycin resistance over the 7-year period. Tetracycline resistance appeared to decrease consistently, whereas methicillin resistance was observed from 2005. About 2.7% (11/402) were resistant to three or more antimicrobials. Genotyping of the 17 methicillin-resistant S. aureus (MRSA) isolated from each cow revealed two staphylococcal cassette chromosome mec (SCCmec) types (IV and IVa), three spa types (t286, t324, and untypable), and two sequence types (ST1 and ST72). Eleven of 17 (64.7%) MRSA strains belonged to SCCmec IVa-t324-ST72. The rest of strains belonged to SCCmec IVa-t286-ST1 (n?=?3) and SCCmec IV-untypable-ST72 (n?=?3). None of the MRSA carried the Panton-Valentine leukocidin gene. These characteristics are the same as those found in community-acquired (CA) MRSA strains prevalent in humans in Korea. Three pulsed-field gel electrophoresis types (A-C) were observed among the 17 MRSA strains examined, and 14 strains belonged to the same pulsed-field gel electrophoresis pattern regardless of their geographical origin and year of isolation. The results of this study provide evidence of CA-MRSA infection in dairy cattle for the first time in Korea.     

Carriage of Staphylococcus aureus and of gram-negative bacilli resistant to third-generation cephalosporins in cirrhotic patients: a prospective assessment of hospital-acquired infections.

OBJECTIVE: To study the relation between Staphylococcus aureus nasal and stool colonization, stool carriage of gram-negative bacilli resistant to third-generation cephalosporins (CephR), and subsequent infections during hospitalization. DESIGN: Prospective study. PATIENTS: 551 cirrhotic patients with 589 consecutive hospital stays. All patients were screened within 48 hours of admission; 589 nasal swabs, 417 stool specimens, and 589 urine samples were analyzed. RESULTS: Carriage rates were 18.8% for methicillin-sensitive S aureus (MSSA), 16.3% for methicillin-resistant S aureus (MRSA), and 13.7% for CephR. We observed 87 episodes of spontaneous bacterial peritonitis, 63 cases of bacteremia, and 167 urinary tract infections occurred. Only 1 case of bacteremia and 4 urinary tract infections due to CephR occurred in patients carrying the same organism in their stools. The risk of MRSA ascitic fluid infections, bacteremia, and urinary tract infections was 3.1% versus 1% (not significant), 8.3% versus 0.8% (P<.001), and 11.4% versus 0.6% (P<.001) in carriers and noncarriers, respectively. Pulsed-field gel electrophoresis (PFGE) of isolates from 16 patients infected by MSSA (3 cases) and MRSA (13 cases) demonstrated that the colonizing strains matched the invasive strains in the 3 MSSA cases and in 8 of 13 MRSA cases. CONCLUSION: Carriage of CephR strains is not associated with subsequent infection by these organisms in hospitalized cirrhotic patients. In contrast, MRSA carriage was an important risk factor for MRSA bacteremia and urinary tract infection.     

金黄色葡萄球菌的耐药性分析及流行病学分型

目的 研究金黄色葡萄球菌(SAU)的耐药性及流行病学分型特点.方法 应用Microscan Walkaway96全自动细菌鉴定仪进行菌种鉴定及抗菌药物敏感性试验;应用脉冲凝胶电泳将随机选取的部分MRSA进行分子流行病学分型.结果 共分离497株金黄色葡萄球菌,未发现万占霉素及利奈唑胺耐药及中介的菌株,SAU对磺胺甲噁唑/甲氧苄啶及氯霉素耐药率相对较低,分别为12.6％、5.9％ ;40株MRSA脉冲凝胶电泳分型共有6个分型,其中A型及其亚型最多,占47.5％,B型占20.0％,其余4个分型占32,5％.结论 万古霉素及利奈唑胺是对MRSA最为敏感的药物,医院MRSA分子流行病学分型以脉冲凝胶电泳分型A型及B型为主.     

Methicillin resistant Staphylococcus aureus infections-implications in hospital infection control

BACKGROUND: A significant part of nosocomial infections are caused by methicillin resistant Staphylococcus aureus (MRSA). Nosocomial MRSA are known to be multidrug resistant and thus difficult to treat. METHODS: A 2 year study was conducted between January 2001 and December 2002 at Karnataka Institute of Medical Sciences Hospital, Hubli to assess the prevalence of MRSA and its antibiotic susceptibility pattern in various wards. RESULTS: S. aureus was isolated from 714 patients, 283 (37.53%) of which exhibited methicillin resistance. Although these MRSA were multidrug resistant in all the wards, the problem was more severe in NICU and orthopedic wards. CONCLUSION: The results highlight the need for effective implementation of infection control measures in the hospital. There is a need for the judicious use of antimicrobial agents in the hospital and outside as their indiscriminate use can exert pressure in selecting out MRSA and other multidrug resistant organisms.     

2011—2015年四川省金黄色葡萄球菌对万古霉素及利奈唑胺耐药性变迁

目的了解四川省金黄色葡萄球菌对万古霉素、利奈唑胺耐药情况,为临床抗感染治疗提供参考依据。方法收集四川省71所医院2011-2015年临床分离的金黄色葡萄球菌、耐甲氧西林金黄色葡萄球菌（MRSA）,并计算每年万古霉素与利奈唑胺对金黄色葡萄球菌、MRSA的最低抑菌浓度（MIC）值。结果5年共收集51 976株金黄色葡萄球菌,包括MRSA 14 361株,MRSA检出率由2011年的36.02%下降至2015年的25.56%,呈下降趋势(χ2=160.72,P＜0.05）。2011-2015年万古霉素对金黄色葡萄球菌的MIC50值分别为：1、0.5、0.5、1、1 μg/mL,MIC90值由1 μg/mL上升至2 μg/mL;利奈唑胺MIC50值均为2 μg/mL,MIC90值由2 μg/mL上升至4 μg/mL。2011-2015年万古霉素对MRSA的MIC50、MIC90值变化较明显,分别由0.5、1 μg/mL上升至2 μg/mL;利奈唑胺MIC50值均为2 μg/mL,MIC90值由2 μg/mL上升至4 μg/mL。结论MRSA的检出率有下降趋势,但万古霉素、利奈唑胺对其MIC50及MIC90值总体有上升趋势,需继续加强细菌耐药监测,为临床合理应用抗菌药物提供帮助。     

Antimicrobial susceptibility of Staphylococcus aureus isolated from hospital inpatients, 2009: report from the Australian Group on Antimicrobial Resistance

In 2009, the Australian Group on Antimicrobial Resistance (AGAR) conducted a period-prevalence survey of clinical Staphylococcus aureus isolated from hospital inpatients. Thirty medical microbiology laboratories from each state and mainland territory participated. Specimens were collected more than 48 hours post-admission. Isolates were tested by Vitek2 (AST-P579 card) and by Etest for daptomycin. Nationally, the proportion of S. aureus that were MRSA was 33.6%, ranging from 27.3% in South Australia to 41.4% in New South Wales/Australian Capital Territory. Resistance to the non-beta-lactam antimicrobials was common except for rifampicin, fusidic acid, daptomycin and high-level mupirocin. No resistance was detected for vancomycin, teicoplanin, quinupristin-dalfopristin or linezolid. Resistance in the methicillin susceptible S. aureus (MSSA) was rare apart from erythromycin (12%) and absent for vancomycin, teicoplanin, daptomycin, quinupristin-dalfopristin and linezolid. The proportion of methicillin resistant S. aureus (MRSA) has remained stable since the first AGAR inpatient survey in 2005 yet during the same time frame resistance to many antimicrobials, in particular tetracycline, trimethoprim-sulphamethoxazole and gentamicin, has significantly decreased. This suggests that non-multi-resistant community-associated MRSA (CA-MRSA) clones are becoming more common in the hospital setting and replacing the long-established multi-resistant clones such as ST239-III (Aus 2/3 EMRSA). Given hospital outbreaks of CA-MRSA are thought to be extremely rare it is most likely that patients colonised at admission with CA-MRSA have become infected with the colonising strain during their hospital stay.     

Bactériémies à bactéries multirésistantes chez les greffés de cellules souches-hématopoïétiques

Background:

Bacteremia become fearsome in hematopoietic stem cell transplant (HSCT) recipients with the emergence of multidrug-resistant (MDR) strains.

Aim:

Our purpose was to investigate the prevalence of MDR bacteremia in HSCT recipients at the Tunisian National Bone Marrow Transplant Center, associated factors and attributable mortality rate.

Methods:

Our retrospective study (January 2010-December 2017) included all MDR bacteremia in the Hematology department. MDR rods were: extended spectrum beta-lactamase producing Enterobacterales (ESBL-E), P. aeruginosa and A. baumannii resistant to at least three families of antibiotics, methicillin-resistant S. aureus (MRSA) and vancomycin resistant E. faecium (VRE).

Results:

The prevalence of MDR bacteremia among HSCT recipients was 5.9% (48/816) with a stable trend over time (rs=0.18). Neutropenia, prior hospitalization, prior antibiotherapy and prior colonization with MDR pathogens were observed in 59%, 58%, 48% and 31% of cases, respectively. Imipenem was the most prescribed first-line antibiotic (50%). The attributable mortality rate was 13%. MDR bacteria (n=48) belonged to ESBL-E (60%), P. aeruginosa (19%), A. baumannii (13%), MRSA (4%) and VRE (4%). For ESBL-E and P. aeruginosa, the rates of antibiotic resistance were respectively, 17% and 44% to imipenem, 31% and 56% to amikacin and 15% and 0% to colistin. Strains of A. baumannii were susceptible only to colistin. The MRSA (n=2) were resistant to ciprofloxacin and gentamicin and susceptible to glycopeptides. The VRE (n=2) were susceptible to linezolid and tigecycline.

Conclusion:

Low prevalence of MDR bacteremia in HSCT recipients but high attributable mortality rate, requiring reinforcement of hygiene measures.     

徐州地区116株MRSA耐药性分析与分子流行病学调查

目的了解耐甲氧西林金黄色葡萄球菌(MRSA)感染现状和耐药机制,为临床合理用药提供依据。方法收集徐州地区2012—2015年各类标本中分离的金黄色葡萄球菌(SA),用头孢西丁纸片扩散法初筛MRSA菌株,扩增mecA基因进行确认,K-B法检测MRSA对药物的敏感性,E-test法测定万古霉素的最低抑菌浓度(MIC),采用多重PCR进行葡萄球菌染色体mec(SCCmec)基因分型。结果 2012—2015年210株SA共检出MRSA116株,其中mecA基因阳性114株,MRSA总检出率为55.24%。MRSA对万古霉素、奎奴普丁/达福普汀、替考拉宁和利奈唑胺的敏感率均为100%,对氯霉素和呋喃妥因的耐药率最低,分别为15.52%、1.72%,MRSA对10种抗菌药物的耐药率80%;MRSA对青霉素类、氨基糖苷类、红霉素、喹诺酮类、磺胺类、利福平、四环素、克林霉素的耐药率高于甲氧西林敏感金黄色葡萄球菌(MSSA)。2012—2015年万古霉素对MRSA的MIC均为1.0μg/mL,MIC90均为1.5μg/mL,2015年发现1株MRSA的万古霉素MIC为2.0μg/mL。116株MRSA分型结果显示,SCCmecII型11株(9.48%),SCCmecIII型85株(73.28%),SCCmecIV型4株(IVa和IVb型各2株,均为1.72%),未分型MRSA16株(13.79%),未检出SCCmecI和V型。结论 MRSA呈严重的多重耐药,对万古霉素MIC无漂移,临床MRSA分离株以SCCmecIII型为主,临床应采取感染控制措施,控制MRSA感染。     

Apport du kit Servitex Staphylocoque MRSA® dans le diagnostic rapide des souches de Staphylococcus aureus résistantes à la méticilline

Objective – An efficient initial antibiotic therapy for patients infected by methicillin resistant Staphylococcus aureus (MRSA) improves the health prognostic in term of morbidity and mortality. The authors wanted to assess the Servitex Staphylocoque MRSA test^®: a rapid (30 min) slide latex agglutination test used to determine methicillin resistance by detecting PBP 2a in Staphylococcus aureus.Method – Sixty five Staphylococcus aureus clinical isolates (53 heterogeneous methicillin resistant S. aureus, nine homogeneous methicillin resistant S. aureus, three methicillin susceptible strains), and two control strains (ATCC 25923, CIP 6525) were studied. These strains were tested by various methods: agar diffusion with 5 μg oxacillin disk tested both at 30°C on Mueller-Hinton medium and at 37°C and on Mueller-Hinton plus 4% NaCl; latex test Servitex MRSA^® tested with two inocula (5 and 10 cfu); and dot blot hybridization with the mecA probe.Results – The methods used to detect methicillin resistance were of similar sensitivity except for the latex test Servitex MRSA^® with a 5 cfu inoculum which detected resistance in only 87% of the cases. A 100% accuracy was restored if a 10 cfu inoculum was used for the latex test Servitex MRSA^®.Comments – Standardization of the initial inoculum appears to be necessary for the reliable detection of methicillin resistance by the latex test. In a clinical laboratory, the use of the latex test is thus restricted to very specific cases if results are to be obtained in less than 48 hours.     

Predominant staphylococci in the intensive care unit of a paediatric hospital

Coagulase-negative staphylococci cause a significant number of infections, especially in immunocompromised patients, including premature neonates. Nosocomial strains present in the environment create a special risk.We studied staphylococci isolated from the intensive care unit of a paediatric teaching hospital over the period of six months in 1997. Biotyping and species identification were performed; resistance to methicillin and other beta-lactam antibiotics and patterns of resistance to antimicrobial agents were determined.Staphylococcus cohnii was the predominant species of 147 isolates of staphylococci recovered from the ward environment. Strains were resistant to several antibiotics and 97% were resistant to methicillin. In isolates from infants (72) methicillin-resistant strains of Staphylococcus epidermidis were predominant. Susceptibility to beta-lactams (penicillin, amoxycillin, amoxycillin-clavulanic acid and cephalosporins: cephalothin, cefuroxime and cefotaxime) showed differences between the two species. Some S. cohnii were susceptible to penicillin and amoxycillin despite methicillin-resistance. S. epidermidis were relatively susceptible to amoxycillin-clavulanic acid and cephalosporins. All strains investigated were susceptible to vancomycin, but nearly 30% demonstrated high-level resistance to mupirocin. The search for strains of the same origin showed clones belonging to S. epidermidis, S. hominis and S. saprophyticus but not S. cohnii.A large number of multiresistant, phenotypically different S. cohnii strains surviving in the ward environment may provide a reservoir of antimicrobial resistance genes.