During a hospital-wide prospective point prevalence survey of faecal carriage and environmental colonisation of vancomycin-resistant enterococci in a tertiary care university hospital in Athens (Greece), five clinical and one environmental isolate from a light switch (all in the haematology ward) were identified as vancomycin- and linezolid-resistant vanA-positive Enterococcus faecium (VLRE). The studied isolates exhibited a linezolid minimum inhibitory concentration of 12microg/mL and carried at least one mutated copy of the 23S rRNA gene, as shown by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis to detect the G2576T mutation. The enterococcal surface protein (esp) gene was detected by PCR in all isolates. Molecular typing with pulsed field gel electrophoresis (PFGE) showed that the environmental and four of the five clinical isolates were genetically related. None of the colonised patients were previously exposed to linezolid, although heavy linezolid use was noted in the institution. A case-control study was performed to assess risk factors for VLRE colonisation. In univariate analysis, immunodeficiency, underlying haematological malignancy, duration of any antimicrobial treatment before VLRE isolation, and hospitalisation in the haematology ward were pointed out as possible risk factors. A multidisciplinary approach including intensified hand hygiene, patient contact isolation, disinfection of the inanimate environment and antibiotic restriction resulted in early containment of the VLRE colonisation outbreak.
[Show abstract][Hide abstract] ABSTRACT: The seventh year of the Zyvox Annual Appraisal of Potency and Spectrum Program (2008) continues to monitor the in vitro activities of linezolid and comparator agents tested against Gram-positive pathogens in Latin America, Europe, Canada, and the Asia-Pacific region. Linezolid is an oxazolidinone approved for the treatment of vancomycin-resistant Enterococcus faecium infections, complicated skin and soft tissue infections, and nosocomial pneumonia caused by various Gram-positive species including methicillin-resistant Staphylococcus aureus (MRSA). Surveillance isolates were submitted from 64 medical centers (24 countries) for a total of 6121 strains. Each country was requested to send 200 consecutive isolates in 6 targeted pathogen categories to a central processing laboratory, except the United Kingdom, Japan, and China where more strains were processed (400, 400, and 800, respectively). Reference broth microdilution susceptibility testing methods were used to test the following organism groups: S. aureus (3240), coagulase-negative staphylococci (CoNS) (748), enterococci (864), Streptococcus pneumoniae (655), viridans group (297), and beta-hemolytic streptococci (317). Eight linezolid-resistant (LZD-R) isolates were detected in 7 countries (Italy , France, China, Brazil, Sweden, Germany, and United Kingdom) among the enterococci (Enterococcus faecalis  and E. faecium ) and CoNS (3 Staphylococcus epidermidis). Five LZD-R isolates contained 23S rRNA mutations (G2576T or G2447T), and 2 strains had undeterminable resistance mechanisms. One CoNS (Italy) contained the mobile cfr gene. Vancomycin-resistant enterococci rates ranged from 0.0% in several countries to 59.4% in Taiwan. All streptococci were linezolid susceptible (MIC(90), 1 microg/mL). In conclusion, the activity of linezolid remained uniform and stable across the sampled geographic regions studied when compared to the 2006 to 2007 results. Documented LZD-R remains rare (only 0.13% overall but highest for CoNS [0.41%] and enterococci [0.69%]) among the 24 countries sampled for the 6 different pathogen groups. Rates of clindamycin resistance and the frequency of MRSA varied by geographic region and between nations; therefore, like oxazolidinones, it requires continued surveillance for changing resistance patterns.
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