Plasmid-mediated quinolone resistance (PMQR) and mutations in the topoisomerase genes of Salmonella enterica strains from Brazil

The objective of this study was to identify mutations in the Quinolone Resistance Determining sources Regions (QRDR) of the gyrA, gyrB, parC, and parE genes and to determine if any of the qnr variants or the aac(6')-Ib-cr variant were present in strains of Salmonella spp. isolated in Brazil. A total of 126 Salmonella spp. strains from epidemic (n = 114) and poultry (n = 12) origin were evaluated. One hundred and twelve strains (88.8%) were resistant to nalidixic acid (NAL) and 29 (23.01%) showed a reduced susceptibility to ciprofloxacin (Cip). The mutations identified were substitutions limited to the QRDR of the gyrA gene in the codons for Serine 83, Aspartate 87 and Alanine 131. The sensitivity to NAL seems to be a good phenotypic indication of distinguishing mutated and nonmutated strains in the QRDR, however the double mutation in gyrA did not cause resistance to ciprofloxacin. The qnrA1 and qnrB19 genes were detected, respectively, in one epidemic strain of S. Enteritidis and one strain of S. Corvallis of poultry origin. Despite previous detection of qnr genes in Brazil, this is the first report of qnr gene detection in Salmonella, and also the first detection of qnrB19 gene in this country. The results alert for the continuous monitoring of quinolone resistance determinants in order to minimize the emergence and selection of Salmonella spp. strains showing reduced susceptibility or resistance to quinolones.

Atypical phenotypic characteristics of klebsiella pneumoniae isolates from an outbreak in a neonatal intensive care unit in Brazil

Extended-spectrum beta-Lactamase-producing (ESBL) Klebsiella sp.isolates from an outbreak in a Neonatal Intensive Care Unit (NICU) at a teaching hospital in Londrina, Paraná State, Brazil, presented atypical phenotypic characteristics that hampered their identification and the distinction between Klebsiella and Enterobacter species. Ten isolates were identified as K. pneumoniae due to negative reactions for motility and inducible beta-lactamase test (ESBL and AmpC) despite being positive for ornithyne descarboxilase. These isolates were genotyped by ribotyping and polymerase chain reaction (PCR) with repetitive extragenic palindromic sequences (REP). Ribotyping by means of an automated instrument and EcoRI and Pvu II as restriction enzymes resulted indetection of K. pneumoniae subspecie pneumoniae RIBO1 222-36-S-5 ribotype. Typing by REP-PCR showed that the 17 isolates from the outbreak were highly similar, belonging to one cluster with 100 percent of similarity, and that they presented more than 70 percent of similarity with K. pneumoniae ATCC 13883 and ATCC 10031, and 25 percent of similarity with E. aerogenes CDC 1680. In conclusion, the isolates of the outbreak were identified as Klebsiella pneumoniae, despite presenting ornithyne descarboxilase enzyme, which is an atypical characteristic of this Klebsiella species.

Isolados de Klebsiella sp. produtora de beta-lactamase de espectro estendido (ESBL), responsável por um surto na Unidade Neonatal de Terapia Intensiva (UNTI) do Hospital Universitário de Londrina, Paraná, Brasil apresentaram características fenotípicas atípicas que dificultaram sua identificação e a diferenciação entre as espécies Klebsiella pneumoniae e Enterobacter aerogenes. Dez isolados foram identificados como K. pneumoniae devido às reações negativas para motilidade e produção de enzimas beta-lactamases (ESBL e AmpC). Embora apresentassem teste positivo para ornitina descarboxilase. Estes isolados foram genotipados por ribotipagem e por reação em cadeia da polimerase (PCR) com oligonucleotídeos para "repetitive extragenic palindromic sequences" (REP). A ribotipagem com as enzimas de restrição EcoRI e Pvu II detectou o ribotipo de K. pneumoniae subespécie pneumoniae RIBO1 222-36-S-5. A técnica de REP-PCR mostrou que os isolados do surto foram similares, pertencentes a um grupo com 100 por cento de similaridade, e apresentaram mais de 70 por cento de similaridade com amostras padrão de K. pneumoniae (ATCC 13883 e 10031), e 25 por cento de similaridade com E. aerogenes CDC 1680. Concluindo, os isolados do surto da NICU mostraram se geneticamente relacionados e foram identificados como Klebsiella pneumoniae, embora apresentassem ornitina descarboxilase, característica atípica para esta espécie de Klebsiella.