Isolation in Brazil of nosocomial Staphylococcus aureus with reduced susceptibility to vancomycin.

OBJECTIVE: To evaluate the possible presence of vancomycin-resistant Staphylococcus aureus (VRSA) in a Brazilian hospital. DESIGN: Epidemiological and laboratory investigation of nosocomial VRSA. METHODS: 140 methicillin-resistant S aureus strains isolated between November 1998 and October 1999 were screened for susceptibility to vancomycin. The screening was carried out by using brain-heart infusion agar (BHIA) supplemented with 4, 6, and 8 microg/mL of vancomycin. The minimum inhibitory concentration (MIC) determination was carried out as standardized by the National Committee for Clinical Laboratory Standards using the broth macrodilution, agar-plate dilution, and E-test methods. PATIENTS: Hospitalized patients exposed to vancomycin. RESULTS: 5 of the 140 isolates had a vancomycin MIC of 8 microg/mL by broth macrodilution, agar plate dilution, and E-test methods. Four VRSA strains were isolated from patients in a burn unit who had been treated with vancomycin for more than 30 days, and one from an orthopedic unit patient who had received vancomycin treatment for 7 days. Pulsed-field gel electrophoresis characterized four of the VRSA strains as belonging to the Brazilian endemic clone. All five strains were negative for vanA, vanB, and vanC genes by polymerase chain reaction. Transmission electron microscopy of the five strains revealed significantly thickened cell walls. One patient died due to infection caused by the VRSA strain. CONCLUSIONS: This is the first report of isolation of VRSA in Brazil and the first report of isolation of multiple VRSA strains from one facility over a relatively short period of time. This alerts us to the possibility that VRSA may be capable of nosocomial transfer if adequate hospital infection control measures are not taken.     

Staphylococcus aureus with reduced susceptibility to vancomycin isolated from a patient with fatal bacteremia

A Staphylococcus aureus isolate with reduced susceptibility to vancomycin was obtained from a dialysis patient with a fatal case of bacteremia. Comparison of the isolate with two methicillin-resistant S. aureus (MRSA) isolated obtained from the same patient 4 months earlier suggests that the S. aureus with reduced susceptibility to vancomycin emerged from the MRSA strain with which the patient was infected. Atypical phenotypic characteristics, including weak or negative latex-agglutination test results, weak or negative-slide coagulase test results, heterogeneous morphologic features, slow rate of growth, and vancomycin susceptibility (by disk diffusion test) were observed.     

Laboratory reporting of Staphylococcus aureus with reduced susceptibility to vancomycin in United States Department of Veterans Affairs facilities

A national survey was sent to all appropriate Veterans Health Administration (VA) medical facilities asking about the ability to test for Staphylococcus aureus with reduced susceptibility to vancomycin (SARV) (MICs >4 microg/mL). For those with this ability, a request was made for the number of patients having SARV isolated during a 1-year period. Nineteen patients from eight sites across the country had isolation of SARV. Of these, MicroScan (Dade Behring, Inc, MicroScan Division, West Sacramento, CA) technology was used for 17 patients, Vitek (Hazelwood, MO) was used for 1 of the remaining 2 patients, and E-test (AB Biiodisk North America, Inc, Piscataway, NJ) for the other. All patients with this organism had microbiology testing done onsite in the reporting VA facility's College of American Pathologists-approved laboratory. For comparison, similar data were obtained for a 1-year period 2 years prior to the current survey; seven patients from four sites were verified to have a SARV. Between the two survey periods the reported cases of SARV increased 170%, indicating a need for continued surveillance and potentially a need to initiate a collection of isolates for further analysis.     

Methicillin-resistant Staphylococcus aureus in Europe, 1999-2002

We explored the variation in proportions of methicillin-resistant Staphylococcus aureus (MRSA) between and within countries participating in the European Antimicrobial Resistance Surveillance System and temporal trends in its occurrence. This system collects routine antimicrobial susceptibility tests for S. aureus. We examined data collected from January 1999 through December 2002 (50,759 isolates from 495 hospitals in 26 countries). MRSA prevalence varied almost 100-fold, from <1% in northern Europe to >40% in southern and western Europe. MRSA proportions significantly increased in Belgium, Germany, Ireland, the Netherlands, and the United Kingdom, and decreased in Slovenia. Within countries, MRSA proportions varied between hospitals with highest variance in countries with a prevalence of 5% to 20%. The observed trends should stimulate initiatives to control MRSA at national, regional, and hospital levels. The large differences between hospitals indicate that efforts may be most effective at regional and hospital levels.     

Vancomycin susceptibility within methicillin-resistant Staphylococcus aureus lineages

Methicillin-resistant Staphylococcus aureus (MRSA) with reduced vancomycin susceptibility vancomycin-intermediate S. aureus (VISA) has been reported from many countries. Whether resistance is evolving regularly in different genetic backgrounds or in a single clone with a genetic predisposition, as early results suggest, is unclear. We have studied 101 MRSA with reduced vancomycin susceptibility from nine countries by multilocus sequence typing (MLST), characterization of SCCmec (staphylococcal chromosomal cassette mec), and agr (accessory gene regulator). We found nine genotypes by MLST, with isolates within all five major hospital MRSA lineages. Most isolates (88/101) belonged to two of the earliest MRSA clones that have global prevalence. Our results show that reduced susceptibility to vancomycin has emerged in many successful epidemic lineages with no clear clonal disposition. Increasing antimicrobial resistance in genetically distinct pandemic clones may lead to MRSA infections that will become increasingly difficult to treat.     

Staphylococcus aureus infections in US veterans, Maryland, USA, 1999-2008

Trends in Staphylococcus aureus infections are not well described. To calculate incidence in overall S. aureus infection and invasive and noninvasive infections according to methicillin susceptibility and location, we conducted a 10-year population-based retrospective cohort study (1999-2008) using patient-level data in the Veterans Affairs Maryland Health Care System. We found 3,674 S. aureus infections: 2,816 (77%) were noninvasive; 2,256 (61%) were methicillin-resistant S. aureus (MRSA); 2,517 (69%) were community onset, and 1,157 (31%) were hospital onset. Sixty-one percent of noninvasive infections were skin and soft tissue infections; 1,112 (65%) of these were MRSA. Ten-year averaged incidence per 100,000 veterans was 749 (± 132 SD, range 549-954) overall, 178 (± 41 SD, range 114-259) invasive, and 571 (± 152 SD, range 364-801) noninvasive S. aureus infections. Incidence of all S. aureus infections significantly increased (p<0.001), driven by noninvasive, MRSA, and community-onset infections (p<0.001); incidence of invasive S. aureus infection significantly decreased (p<0.001).     

Reduced susceptibility of Staphylococcus aureus to vancomycin--a review of current knowledge.

Antibiotic options for patients with methicillin resistant Staphylococcus aureus infections are severely limited. Unfortunately, infections with S. aureus with reduced susceptibility to vancomycin and teicoplanin have been recently reported for the first time. Commonly used laboratory methods for determining antibiotic susceptibility may be inadequate for detecting reduced susceptibility to vancomycin. Even though no confirmed cases have yet been detected in Australia, a high index of suspicion must be maintained for the occurrence of such organisms. Strategies for prevention of the spread of S. aureus with reduced susceptibility to vancomycin should be prepared by Australian hospitals prior to their first cases being identified. This article outlines the background to this developing issue and discusses laboratory methods and findings, with some current recommendations for diagnostic laboratories.     

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.     

Hospitalizations and deaths caused by methicillin-resistant Staphylococcus aureus, United States, 1999-2005

Hospital-acquired infections with Staphylococcus aureus, especially methicillin-resistant S. aureus (MRSA) infections, are a major cause of illness and death and impose serious economic costs on patients and hospitals. However, the recent magnitude and trend of these infections have not been reported. We used national hospitalization and resistance data to estimate the annual number of hospitalizations and deaths associated with S. aureus and MRSA from 1999 through 2005. During this period, the estimated number of S. aureus-related hospitalizations increased 62%, from 294,570 to 477,927, and the estimated number of MRSA-related hospitalizations more than doubled, from 127,036 to 278,203. Our findings suggest that S. aureus and MRSA should be considered a national priority for disease control.     

临床不同标本分离金黄色葡萄球菌的药物敏感性

目的了解某院金黄色葡萄球菌感染分布及药物敏感性。方法对2011年1月-2012年8月该院分离的520株金黄色葡萄球菌标本来源和药敏结果进行分析。结果520株金黄色葡萄球菌中,耐甲氧西林金黄色葡萄球菌（MRSA）总检出率为23.27%(121/520),其中痰标本MRSA检出率最高,达80.82%,其次是尿液（33.33%）、血液（25.00%）、引流物标本（18.31%）,皮肤组织检出率最低,仅11.38%。未发现对万古霉素和利奈唑胺耐药的金黄色葡萄球菌;金黄色葡萄球菌对万古霉素、利奈唑胺、复方磺胺甲口恶唑、呋喃妥因均较敏感。皮肤组织来源的MRSA对庆大霉素、左氧氟沙星、环丙沙星、莫西沙星、利福平、四环素的敏感率高于其他标本来源的MRSA（P＜0.05）;对红霉素、克林霉素敏感率低于其他标本来源MRSA（P＜0.05）。MRSA对青霉素完全耐药,其中社区感染MRSA对庆大霉素、左氧氟沙星、环丙沙星、莫西沙星、利福平、四环素的敏感率高于医院感染MRSA（P＜0.05）;对红霉素、克林霉素、复方磺胺甲口恶唑的敏感率低于医院感染MRSA（P＜0.05）。结论金黄色葡萄球菌是该院分离的重要病原菌,耐药性强,临床应根据药敏试验结果合理使用抗菌药物。     

Staphylococcus aureus resistant to vancomycin--United States, 2002

Staphylococcus aureus is a cause of hospital- and community-acquired infections. In 1996, the first clinical isolate of S. aureus with reduced susceptibility to vancomycin was reported from Japan. The vancomycin minimum inhibitory concentration (MIC) result reported for this isolate was in the intermediate range (vancomycin MIC=8 microg/mL) using interpretive criteria defined by the National Committee for Clinical Laboratory Standards. As of June 2002, eight patients with clinical infections caused by vancomycin-intermediate S. aureus (VISA) have been confirmed in the United States. This report describes the first documented case of infection caused by vancomycin-resistant S. aureus (VRSA) (vancomycin MIC > or = 32 microg/mL) in a patient in the United States. The emergence of VRSA underscores the need for programs to prevent the spread of antimicrobial-resistant microorganisms and control the use of antimicrobial drugs in health-care settings.     

Diminished susceptibility to daptomycin accompanied by clinical failure in a patient with methicillin-resistant Staphylococcus aureus bacteremia.

We cared for a patient with methicillin-resistant Staphylococcus aureus bacteremia who experienced clinical failure with daptomycin. The failure was accompanied by progressive elevation of the daptomycin minimum inhibitory concentration during treatment. DNA fingerprinting confirmed that the minimum inhibitory concentration elevation occurred within the same strain of methicillin-resistant Staphylococcus aureus. This observation provides important new information to clinicians who adopt this promising drug for treatment of serious infections caused by methicillin-resistant Staphylococcus aureus.     

2010-2011年血液中金黄色葡萄球菌药敏分析

目的 动态分析和监测2010年与2011年住院患者血液中分离的金黄色葡萄球菌耐药性,为临床合理使用抗菌药物提供依据.方法 采用全自动微生物分析仪VITEK-32进行细菌鉴定,用K-B法进行药敏试验,并用WHONET5.5对其耐药性进行分析.结果 2010年与2011年分别在住院患者血液中分离出33株和43株金黄色葡萄球菌;其对万占霉素、替考拉宁、利奈唑胺、呋喃妥因的敏感率达100.0％,对磺胺甲噁唑/甲氧苄啶的药物敏感性增加,2010年对氨苄西林/舒巴坦的敏感率为80.0％,2011年其敏感性降低至56.1％(P＜0.01);2010年对红霉素的敏感率为27.3％,2011年其敏感性降低至23.3％(P＜0.05);2010年对利福平的敏感率为92.9％,2011年其敏感性降低至75.6％(P＜0.01);在临床常用的14种抗菌药物中,有9种均产生了明显的耐药性,差异有统计学意义(P＜0.05或P＜0.01).结论 连续两年血液中金黄色葡萄球菌耐药性逐年出现了明显增加趋势,并呈不断上升,但对万占霉素、替考拉宁、利奈唑胺仍保持较高的敏感性.     

Staphylococcus aureus bacteremia, Australia

Staphylococcus aureus bacteremia (SAB) is common and increasing worldwide. A retrospective review was undertaken to quantify the number of cases, their place of acquisition, and the proportions caused by methicillin-resistant S. aureus (MRSA) in 17 hospitals in Australia. Of 3,192 episodes, 1,571 (49%) were community onset. MRSA caused 40% of hospital-onset episodes and 12% of community-onset episodes. The median rate of SAB was 1.48/1,000 admissions (range 0.61-3.24; median rate for hospital-onset SAB was 0.7/1,000 and for community onset 0.8/1,000 admissions). Using these rates, we estimate that approximately 6,900 episodes of SAB occur annually in Australia (35/100,000 population). SAB is common, and a substantial proportion of cases may be preventable. The epidemiology is evolving, with >10% of community-onset SAB now caused by MRSA. This is an emerging infectious disease concern and is likely to impact on empiric antimicrobial drug prescribing in suspected cases of SAB.