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.

bIn this study, we report the early expansion, evolution, and characterization of a multiresistant Klebsiella pneumoniae clone that was isolated with increasing frequency from inpatients in a tertiary-care university hospital in Brazil. Seven carbapenem-and quinolone-resistant and polymyxin B-susceptible or -resistant K. pneumoniae isolates isolated between December 2012 and February 2013 were investigated. Beta-lactamase-and plasmid-mediated quinolone resistance (PMQR)-encoding genes and the genetic environment were investigated using PCR, sequencing, and restriction fragment length polymorphism (RFLP). Clonal relatedness was established using XbaI-pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and phylogenetic group characterization. Plasmid analyses included PCR-based replicon typing (PBRT) and hybridization of the S1-PFGE product, plasmid MLST, and conjugation experiments. Virulence potential was assessed by PCR by searching for 10 virulence factor-encoding genes (ureA, fimH, kfuBC, uge, wabG, magA, mrkD, allS, rmpA, and cf29a) and by phenotypic tests to analyze the hypermucoviscous phenotype. The genetic context of a multidrug-resistant and extensively drug-resistant K. pneumoniae ST11-KpI clone harboring IncFIIk-Tn4401a-bla KPC-2 , qnrS1, and bla CTX-M-2 was found. Moreover, three isolates displayed high resistance to polymyxin B (MICs ‫؍‬ 32, 32, and 128 mg/liter) as well as mucous and hypermucoviscous phenotypes. These bacteria also harbored ureA, fimH, uge, wabG, and mrkD, which code for virulence factors associated with binding, biofilm formation, and the ability to colonize and escape from phagocytosis. Our study describes the association of important coresistance and virulence factors in the K. pneumoniae ST11 international high-risk clone, which makes this pathogen successful at infections and points to the quick expansion and evolution of this multiresistant and virulent clone, leading to a pandrug-resistant phenotype and persistent bacteria in a Brazilian hospital.

Enterococci are leading causes of hospital-acquired infections that are often difficult to treat because of high-level aminoglycoside and glycopeptide resistance. Vancomycin-resistant enterococci are a global problem, and have been isolated with increasing frequency in hospitals in Brazil. The objective of this study was to determine the genetic relatedness of vancomycin-resistant Enterococcus faecium (VREFM) and vancomycin-sensitive E. faecium (VSEFM) isolated from human infections and faecal sources in Brazil, and to compare these isolates with those from domesticated animals. Isolates (n = 56) were classified by multilocus sequence typing (MLST) and assessed for putative virulence traits. The acm gene was detected in 98% of all isolates. The 56 isolates studied comprised 26 different MLST types. VSEFM isolates from the faeces of pigs were found to be distinct from all human isolates characterised previously by MLST, and were assigned new sequence type (ST) numbers. VREFM isolates were represented by four different STs (ST-114, ST-17, ST-281, ST-50). Among the 26 STs identified in this study, eBURST detected three groups of STs with related allelic profiles, and 19 unrelated STs. Among E. faecium isolates from Brazil, the esp gene was restricted to vancomycin-resistant isolates. Furthermore, isolates classified as ST-17 by MLST, an epidemic strain type isolated internationally with the purK-1 gene, were found among VREFM isolates from Brazil that also harboured the esp and hyl genes.

The occurrence of extended-spectrum-beta-lactamase (ESBL)-producing strains in the community was investigated in a private laboratory located in Juiz de Fora, Brazil. All enterobacterial isolates analysed were collected from urine of human patients between the years 2000 and 2002. ESBL production was confirmed by double disk screening, combination disk method, and Etest ESBL strip. The isoelectric point of each beta-lactamase was determined in the crude extracts from each isolate. Detection of ESBL genes was performed by polymerase chain reaction and the genetic relatedness of the isolates determined by pulsed-field gel electrophoresis (PFGE). Of the 1,481 isolates, 22 (12 Klebsiella pneumoniae, 7 Escherichia coli, 1 Providencia stuartii, 1 Citrobacter freundii, and 1 Serratia marcescens) were identified as ESBL producers. The frequency of ESBL producers in the community was 1.48%. TEM-type enzymes were identified in 95.4% of the isolates, followed by the SHV type. Seven strains produced CTX-M-type enzymes. This study showed that strains producing multiple beta-lactamases are also present in community-acquired bacterial isolates. Multiple strains exhibiting identical PFGE genotypes were found in individual patients indicating a common source of acquisition.