New STs in multidrug-resistant Acinetobacter baumannii harbouring ß-lactamases encoding genes isolated from Brazilian soils.

AIMS: We investigated the resistance profile, presence of ß-lactamases encoding genes and the clonal relationships in Acinetobacter baumannii isolated from Brazilian soils. METHODS AND RESULTS: Soil isolates of A. baumannii were subjected to antimicrobial susceptibility testing by disk diffusion and minimum inhibitory concentration methods. Different ß-lactamases encoding genes were screened by PCR and the molecular typing of these isolates was performed through the multilocus sequence typing. Non-susceptibility to different antibiotics was found, since environmental isolates were classified as multidrug-resistant. The blaSHV gene was the most prevalent, followed by blaGES. All sequence types (STs) found (ST1584, ST1607, ST1608, ST1609, ST1610, ST1611 and ST1612) were described for the first time in this study. CONCLUSION: The wide variety of new alleles and new STs detected in the present study indicates a divergent population compared to studies that are carried out in the clinical environment and points to an even larger genetic diversity within the species than was anticipated. SIGNIFICANCE AND IMPACT OF THE STUDY: A number of the environmental isolates represented multidrug-resistant strains, a phenotype that has been more commonly reported for clinical isolates of A. baumannii; the detection of several ß-lactamase encoding genes in the investigated isolates is of great concern suggesting that there is a large reservoir of these resistance genes in the environment.

Molecular typing of Yersinia pseudotuberculosis strains isolated from livestock in Brazil.

Yersinia pseudotuberculosis can infect a broad range of animals. In Brazil, this bacterium has been isolated from healthy and sick animals from sporadic cases and outbreaks of hemorrhagic gastroenteritis among livestock. However, the molecular diversity of these isolates is little understood. In this study, we used multilocus sequence typing, enterobacterial repetitive intergenic consensus PCR and pulsed-field gel electrophoresis to genotype 40 Y. pseudotuberculosis strains belonging to bio-serogroups 1/O:1a and 2/O:3 isolated between 1982 and 1990 in the southern region of Brazil. All three methodologies clustered the strains into two main clusters according to their bio-serogroups. Good correlations were observed between the clusters and the pathogenic potential of the strains. No correlation among the strains was observed according to geographical origin, host, place, or year of isolation. The grouping of the Y. pseudotuberculosis isolated in Brazil determined by these assays leads us to suggest that Brazilian livestock harbor two subpopulations of Y. pseudotuberculosis.

Molecular characteristics of extended-spectrum ß-lactamase-producing Escherichia coli from Rio de Janeiro, Brazil.

Twenty-five extended-spectrum ß-lactamase (ESBL)-producing Escherichia coli clinical isolates from Rio de Janeiro, Brazil were characterized by isoelectric focusing, PCR and sequencing of bla(ESBL) genes, plasmid-mediated quinolone resistance determinants, phylogenetic groups, replicon typing, pulsed-field electrophoresis, and multilocus sequencing typing. Twenty-three (92%) ESBL-producing E. coli isolates were positive for bla(CTX-M) genes, aac(6')-Ib-cr, and qnrB. Genetic relatedness of ESBL producers clustered seven (28%) CTX-M-15-producing isolates as sequence type (ST)410, clonal complex (CC) 23, and two (8%) as clone O25-ST131. Our results illustrate the predominance of phylogroup A (52%), ST410 (CC 23) and CTX-M-15 among ESBL-producing E. coli isolates from hospitals in Rio de Janeiro.

Changes in vancomycin-resistant Enterococcus faecium causing outbreaks in Brazil.

Enterococci have been implicated in severe human infections as a consequence of associated determinants of virulence and antimicrobial resistance. The majority of vancomycin-resistant Enterococcus faecium (VRE(fm)) connected to outbreaks worldwide pertains to the clonal complex 17 (CC17). In Brazil, the majority of VRE(fm) involved in outbreaks reported so far are not related to CC17. VRE(fm) strains responsible for an outbreak and sporadic cases in hospitals located in the city of Campinas, Brazil, were compared to other VRE(fm) strains in the country. Twenty-two out of 23 E. faecium were vancomycin-resistant and harboured the vanA gene. One vancomycin-susceptible E. faecium (VSE(fm)) strain was included in this study because it was isolated from a patient who one week later harboured a VRE(fm). All strains, except VSE, showed the same alteration in the VanA element characterised by deletion of the left extremity of the transposon and insertion of IS1251 between the vanS and vanH genes. Genes codifying virulence factors such as collagen-adhesin protein, enterococcal surface protein and hyaluronidase were detected in the VRE(fm) and VSE(fm) studied. Both pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) revealed that VRE(fm) and VSE(fm) strains have a clonal relationship. New sequence types (STs) were identified by MLST as ST447, ST448, ST478 and ST412 but all belonged to the CC17. The present study revealed that VRE(fm) outbreaks in Brazil were caused by strains that did not share a common evolutionary history, and that VRE(fm) strains belonging to CC17 could be predominant in Brazil as in other countries.

Determinants of beta-lactam resistance in meningitis-causing Enterobacteriaceae in Brazil.

This study analyzed resistance determinants in extended-spectrum beta-lactamase (ESBL)-producing enterobacteria and the epidemiology of 11 Escherichia coli isolates obtained from meningitis patients in a region of Brazil from 2000 to 2005. ESBL-encoding genes and their genetic environment were investigated by PCR and sequencing. The gene blaCTX-M-2 was identified in 3 different enterobacteria (E. coli, Serratia marcescens, and Proteus mirabilis) downstream of the insertion sequence ISCR1 (localized in class 1 integrons), but not as part of the resistance cassettes region. Multilocus sequence typing (MLST) was used to investigate genetic relationships between the 11 E. coli isolates in this study and strains associated with meningitis in the E. coli MLST database. MLST analysis indicated high genetic diversity among isolates, and no significant genetic relationship was identified with meningitis-causing E. coli in the database. The results in this report reinforce the need to be attentive to meningitis suspected to be due to ESBL-producing enterobacterial isolates, especially where ESBL epidemiology is well known.