To our knowledge, this is the first study to report plasma concentrations over time and urinary recovery of polymyxin B in critically ill patients after intravenous administration. Polymyxin B is eliminated mainly by nonrenal pathways, and the total body clearance appears to be relatively insensitive to renal function. Additional investigations are required to assess the appropriateness of currently recommended doses of this drug for the treatment of severe infections in critically ill persons.

SUMMARYA case-control study, involving patients with positive blood cultures for Klebsiella pneumoniae (KP) or Escherichia coli (EC) EC and controls with positive blood cultures for non-ESBL-KP or EC, was performed to assess risk factors for extended-spectrum-blactamase (ESBL) production from nosocomial bloodstream infections (BSIs). Mortality among patients with BSIs was also assessed. The study included 145 patients (81, 59.5% with K. pneumoniae and 64, 44.1% with E. coli BSI); 51 (35.2%) isolates were ESBL producers and 94 (64.8%) nonproducers. Forty-five (55.6%) K. pneumoniae isolates were ESBL producers, while only six (9.4%) E. coli isolates produced the enzyme. Multivariate analysis showed that recent exposure to piperacillin-tazobactam (adjusted Odds Ratio [aOR] 6.2; 95%CI 1.1-34.7) was a risk factor for ESBL BSI. K. pneumoniae was significantly more likely to be an ESBL-producing isolate than E. coli (aOR 6.7; 95%CI 2.3-20.2). No cephalosporin class was independently associated with ESBLs BSI; however, in a secondary model considering all oxymino-cephalosporins as a single variable, a significant association was demonstrated (aOR 3.7; 95%CI 1.3-10.8). Overall 60-day mortality was significantly higher among ESBL-producing organisms. The finding that piperacillintazobactam use is a risk factor for ESBL-production in KP or EC BSIs requires attention, since this drug can be recommended to limit the use of third-generation cephalosporins.

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Coagulase-negative staphylococci (CNS) are the major cause of nosocomial infections. Methicillinresistant strains are particularly important because they narrow therapeutic options. Detecting methicillin resistance among CNS has been a challenge for years. The objective of this study was to determine the accuracy of an agar screening test (0 . 6 and 4 ìg oxacillin ml À1 ), disc diffusion and the automated MicroScan system to characterize methicillin resistance among CNS. One hundred and seventy five strains were analysed: 41 . 1 % Staphylococcus epidermidis and 59 . 9 % other species; 69 . 1 % were mecA-positive. The results showed that the methods have optimal correlation with the detection of mecA gene for S. epidermidis, Staphylococcus hominis and Staphylococcus haemolyticus. However, accuracy of the tests is impaired when less common species are analysed. The only 100 % accurate test was agar screening with 4 ìg oxacillin ml À1 .

We evaluated clinical outcomes and molecular epidemiology of methicillin-resistant Staphylococcus aureus carrying SCCmecIV recovered from patients who attended at a teaching hospital from Porto Alegre, Brazil. All Panton-Valentine leukocidin (PVL)-producer isolates belonged to clonal complex (CC) 30 (11 isolates, related to Oceania Southwest Pacific clone [OSPC]), and the PVL-negative isolates were typed as CC5 (2 isolates, related to the pediatric clone). Five patients had health care-associated infections (HCAIs) with hospital-onset, 5 HCAIs with community-onset, and 3 community-acquired infections without risks. A high overall mortality (30.8%) was found. This study show that OSPC isolates are not only causing community-associated infections but are also involved in HCAI in our country.