No abstract

This article reports the spread of bla KPC-2 in the Sao Paulo and Rio de Janeiro states, facilitated by globally spread K. pneumoniae clonal complex 258 (CC258) clones (ST258, ST11, and ST437) and a diversity of plasmids (IncFII, IncN, and IncL/M, two untypeable plasmids carrying Tn4401a or Tn4401b) successfully disseminated among species of the Enterobacteriaceae (Enterobacter cloacae, Serratia marcescens, and Citrobacter freundii). It also constitutes the first description of sequence type 258 (ST258) in Brazil, which was associated with a nosocomial hospital outbreak in Ribeirao Preto city.

Sepsis induced by S. aureus was used to investigate whether neutrophil migration failure to infectious focus correlates with lethality in Gram‐positive bacteria‐induced sepsis in mice. By contrast with the sub‐lethal (SL‐group), the lethal (L‐group) intraperitoneal inoculum of S. aureus caused failure of neutrophil migration (92% reduction), high CFU in the exudate, bacteremia and impairment of in vitro neutrophil chemotactic activity. Pre‐treatments of L‐group with adequate doses of aminoguanidine prevented the neutrophil migration failure and improved the survival of the animals (pre‐treated: 43%; untreated: 0% survival). Thus, the impairment of neutrophil migration in the L‐group appears to be mediated by nitric oxide (NO). The injection of S. aureus SL‐inoculum in iNOS deficient (−/−) or aminoguanidine‐treated wild‐type mice (pre‐ and post‐treatment), which did not present neutrophil migration failure, paradoxically caused severe peritonitis and high mortality. This fact is explainable by the lack of NO dependent microbicidal activity in migrated neutrophils. In conclusion, although the NO microbicidal mechanism is active in neutrophils, the failure of their migration to the infectious focus may be responsible for the severity and outcome of sepsis. British Journal of Pharmacology (2002) 136, 645–658; doi:10.1038/sj.bjp.0704734

Reduced susceptibility or resistance to vancomycin has been reported among clinical isolates of staphylococci in previous studies. In the present study we report on the isolation of four vancomycin-resistant staphylococcal strains from healthy carriers inside and outside the hospital environment. These carriers did not receive treatment with any antibiotic. All coagulase-negative staphylococcal strains showed variable levels of resistance to several antimicrobial agents, including oxacillin, and unstable resistance to vancomycin, with decreased vancomycin MICs (<4 mg/liter) after 10 days of passage in a nonselective medium. However, exposure of these revertants to vancomycin selected staphylococcal strains resistant to vancomycin at very high frequencies (10 ؊2 and 10 ؊3 ). The vancomycin resistance in these staphylococcal strains was not mediated by the van gene. The cell wall of the staphylococcal strains studied became thickest after culture in medium containing vancomycin, and the differences in cell wall thickness were statistically significant (P < 0.001). Thus, the thickening of the cell wall in these staphylococcal strains may be an important contributor to vancomycin resistance.

This study constitutes the first epidemiological survey of the three known Qnr determinants among Brazilian isolates and shows their low prevalence in that country, with the qnrB2 gene being mostly identified.