Molecular epidemiology of vancomycin-resistant Enterococcus faecium in Argentina.

OBJECTIVE: To characterize the mechanism of glycopeptide resistance and to determine the genetic relatedness among strains by pulsed-field gel electrophoresis (PFGE) in vancomycin-resistant Enterococcus faecium from Argentina. MATERIALS AND METHODS: A total of 189 vancomycin-resistant single-patient isolates of Enterococcus faecium recovered between January 1997 and December 2000 from 30 hospitals in Argentina were studied. Minimum inhibitory concentrations were determined by the agar dilution method and van genes were detected by PCR. PFGE was used for molecular typing. RESULTS: All isolates except three (vanB) were of genotype vanA. For 189 vancomycin-resistant Enterococcus faecium, SmaI-PFGE indicated 35 clonal types. Most of the isolates (56%) belonged to the same clonal type 1, which was present in 19 hospitals and dominant in 17. CONCLUSIONS: The emergence of vancomycin-resistant Enterococcus faecium in Argentina seems to be related to the intra- and inter-hospital dissemination of an epidemic clone carrying the vanA element.     

Molecular characterization of methicillin-resistant Staphylococcus aureus isolated from a Brazilian university hospital

The aim of this study was to perform SCCmec typing in Staphylococcus aureus isolates and to characterize the clonal profile of these isolates. Forty-six mecA gene-positive strains isolated between 2002 and 2006 were submitted to antimicrobial resistance testing by the E-test, SCCmec typing by multiplex PCR, and clonal profile analysis by pulsed-field gel electrophoresis. Forty-one (89.1%) isolates were typed as SCCmec III and five (10.9%) as SCCmec IV. Four circulating clones were detected, one of them comprising isolates related to the Brazilian epidemic clone. This clone was detected throughout the study period. The SCCmec III isolates were associated with a high rate of multidrug resistance and clonal dissemination of methicillin-resistant S. aureus in the wards of the University Hospital of the Botucatu School of Medicine, Universidade Estadual Paulista.     

Molecular typing of methicillin-resistant Staphylococcus aureus in a university teaching hospital

Plasmid analysis and pulsed-field gel electrophoresis (PFGE) were used to study the epidemiologic relationship among methicillin-resistant Staphylococcus aureus (MRSA) strains isolated at Tokyo Medical and Dental University Hospital. We found that 263 of 276 MRSA isolates had plasmids, which could be classified into 30 different patterns according to the number and plasmid molecular weight. Strains which harboured a single plasmid of approximately 13.4 Mds in molecular weight were the most numerous (55.7% of the isolates). These strains were isolated from 14 of 17 hospital wards. The largest number of strains with this plasmid pattern (33 strains) were isolated from a single ward. PFGE typing was then performed to further confirm the relationships among these 33 strains. The PFGE banding patterns of these strains were highly similar. The antibiogram profiles of these strains were also correlated with the PFGE pattern. Thus, the results suggest that these strains are epidemiologically related and spread throughout the ward. Combined plasmid analysis and PFGE were effective for discriminating the various MRSA isolates.     

Detection of blaOXA-23 in Acinetobacter spp. isolated from patients of a university hospital

IntroductionAcinetobacter spp. have emerged as notorious pathogens involved in healthcare-associated infections. Carbapenems are important antimicrobial agents for treating infections due to multidrug resistant Acinetobacter spp. Different mechanisms may confer resistance to these drugs in the genus, particularly production of class D carbapenemases. OXA-23-like family has been pointed out as one of the predominant carbapenamases among Acinetobacter. The present work aimed to investigate the occurrence of OXA-23-like carbapenemases among Acinetobacter isolates recovered from patients of a university hospital in Niterói, RJ, Brazil.MethodsAntimicrobial susceptibility profiles were determined by disk-diffusion. Imipenem resistant isolates were submitted to Modified Hodge Test in order to screen for carbapenemase production, and later to polymerase chain reaction (PCR) to investigate the presence of bla_OXA-23.ResultsImipenem and meropenem resistance rates were 71.4% and 69.7%, respectively. The Modified Hodge Test revealed carbapenemase production among 76 (89.4%) of the 85 imipenem resistant isolates analyzed; according to PCR results, 81 isolates (95.4%) carried the bla_OXA-23 gene.ConclusionsOXA-23-like enzymes may be an important mechanism of carbapenem resistance among isolates present in the hospital studied.     

Mycobacterium tuberculosis bacteremia in a university hospital.

SETTING: Patients with blood cultures positive for Mycobacterium tuberculosis between 1988 and 1999. OBJECTIVE: To study the clinical and microbiological characteristics of patients with tuberculous bacteremia, including data about evolution and management. DESIGN: Retrospective review of the clinical charts and microbiological records of patients with culture-proven tuberculous bacteremia between 1988-1999. RESULTS: During the study period, 19 patients with culture-proven M. tuberculosis bacteremia were detected (1.42 isolates/patient, 4.7% of all patients with blood cultures for mycobacteria). Four patients were non-infected with the human immunodeficiency virus and 15 were HIV-infected. In four patients blood was the only positive sample. Five patients were diagnosed simultaneously with tuberculosis and HIV infection. Only 13 had a temperature higher than 37.5 degrees C. Most patients had symptoms or signs of respiratory tract involvement, and 11 patients died (10 from tuberculosis). The average time for detection of positive blood cultures was 33.25 days for lysis-centrifugation cultures and 26.46 days for BACTEC cultures. The incidence of M. tuberculosis bacteremia remained stable during the study period. CONCLUSIONS: Although blood cultures are useful for definitive diagnosis of disseminated tuberculosis, the long incubation times made them of limited usefulness in the clinical management of patients. Mortality remains high in these patients.     

河南省部分地区奶牛毕氏肠微孢子虫和芽囊原虫分子流行病学调查

目的 调查河南省奶牛毕氏肠微孢子虫和芽囊原虫流行情况及评估其人兽共患传播风险。方法 基于毕氏肠微孢子虫SSU rRNA内部转录间隔区(ITS)和芽囊原虫核糖体小亚基(SSU rRNA)基因位点对从河南省5个地区,10个奶牛场共采集的1 020份粪便样品进行PCR检测。结果 奶牛毕氏肠微孢子虫和芽囊原虫的感染率分别为21.7%(221/1 020)和19.2%(196/1 020),其中混合感染率为3.5%(36/1 020)。序列分析显示共鉴定了5种毕氏肠微孢子虫人兽共患基因型(D、J、I、BEB4、BEB6)和4种芽囊原虫人兽共患基因型(ST1、ST2、ST4、ST5)。结论 本研究首次对河南地区奶牛芽囊原虫流行情况进行了调查,鉴定的人兽共患基因型具有重要公共卫生意义。     

Susceptibility to vancomycin of methicillin-resistant Staphylococcus aureus isolated in a university hospital in Japan

Intravenous vancomycin was approved in 1991 in Japan and has been widely used for treatment of infections caused by methicillin-resistant Staphylococcus aureus (MRSA). Consequently, ever since the initial discovery of vancomycin intermediate-resistant S. aureus in Japan, the vancomycin resistance of this organism has been a great concern in clinical settings. We investigated whether vancomycin resistance had emerged in MRSA isolated in our hospital since the approval of the use of intravenous vancomycin. Vancomycin susceptibility was evaluated on the basis of minimum inhibitory concentrations determined by the agar dilution method and a heterogeneous resistance examination. The median minimum inhibitory concentration of the 69 MRSA strains isolated in 1988 and the 74 isolated in 1998 was 0.75 microgram/ml and 1.0 microgram/ml, respectively (p < 0.001), however, all of the strains were classified in the susceptible group. None of them was an MRSA heterogeneously resistant to vancomycin (hetero-VRSA), which has been defined as a strain having a 1/10(6) or greater heterogeneously resistant subpopulation to vancomycin. In another set of investigations, no hetero-VRSA were found among 12 other MRSA strains isolated after intravenous administration of vancomycin for 14 or more days (range: 14 to 77 days). We conclude that while the use of intravenous vancomycin may have slightly lowered the vancomycin susceptibility of MRSA in our hospital, the decrease in so small that it may not be significant clinically. In addition, no hetero-VRSA were found in our hospial.     

Molecular epidemiology of <Emphasis Type="Italic">Enterococcus faecium</Emphasis> isolates from an Italian hospital

Background  

Outbreaks of vancomycin-resistant Enterococcus faecium (VRE) strains is an emerging problem worldwide. Even if still relatively uncommon in European hospitals, infections caused by VRE have also been increasing recently in this continent.