Klebsiella pneumoniae is an important opportunistic pathogen that commonly causes nosocomial infections and contributes to substantial morbidity and mortality. We sought to investigate the antibiotic resistance profile, pathogenic potential and the clonal relationships between K. pneumoniae (n = 25) isolated from patients and sources at a tertiary care hospital’s intensive care units (ICUs) in the northern region of Brazil. Most of K. pneumoniae isolates (n = 21, 84%) were classified as multidrug resistant (MDR) with high-level resistance to β-lactams, aminoglycosides, quinolones, tigecycline, and colistin. All the 25 isolates presented extended-spectrum beta-lactamase-producing (ESBL), including carbapenemase producers, and carried the blaKPC (100%), blaTEM (100%), blaSHV variants (n = 24, 96%), blaOXA-1 group (n = 21, 84%) and blaCTX-M-1 group (n = 18, 72%) genes. The K2 serotype was found in 4% (n = 1) of the isolates, and the K1 was not detected. The virulence-associated genes found among the 25 isolates were mrkD (n = 24, 96%), fimH-1 (n = 22, 88%), entB (100%), iutA (n = 10, 40%), ybtS (n = 15, 60%). The genes related with efflux pumps and outer membrane porins found were AcrAB (100%), tolC (n = 24, 96%), mdtK (n = 22, 88%), OmpK35 (n = 15, 60%), and OmpK36 (n = 7, 28%). ERIC-PCR was employed to determine the clonal relationship between the different isolated strains. The obtained ERIC-PCR patterns revealed that the similarity between isolates was above 70%. To determine the sequence types (STs) a multilocus sequence typing (MLST) assay was used. The results indicated the presence of high-risk international clones among the isolates. In our study, the wide variety of MDR K. pneumoniae harboring β-lactams and virulence genes strongly suggest a necessity for the implementation of effective strategies to prevent and control the spread of antibiotic resistant infections.

Molecular typing and virulence markers were used to evaluate the genetic profiles and virulence potential of 106 Yersinia enterocolitica strains. Of these strains, 71 were bio-serotype 4/O : 3, isolated from human and animal clinical material, and 35 were of biotype 1A or 2 and of diverse serotypes, isolated from food in Brazil between 1968 and 2000. Drug resistance was also investigated. All the strains were resistant to three or more drugs. The isolates showed a virulence-related phenotype in the aesculin, pyrazinamidase and salicin tests, except for the food isolates, only two of which were positive for these tests. For the other phenotypic virulence determinants (autoagglutination, Ca ++ dependence and Congo red absorption), the strains showed a diverse behaviour. The inv, ail and ystA genes were detected in all human and animal strains, while all the food isolates were positive for inv, and 3 % of them positive for ail and ystA. The presence of virF was variable in the three groups of strains. The strains were better discriminated by PFGE than by enterobacterial repetitive intergenic consensus PCR (ERIC-PCR). A higher genomic similarity was observed among the 4/O : 3 strains, isolated from human and animal isolates, than among the food strains, with the exception of two food strains possessing the virulence genes and grouped close to the 4/O : 3 strains by ERIC-PCR. Unusually, the results revealed the virulence potential of a bio-serotype 1A/O : 10 strain, suggesting that food contaminated with Y. enterocolitica biotype 1A may cause infection. This also suggests that ERIC-PCR may be used as a tool to reveal clues about the virulence potential of Y. enterocolitica strains. Furthermore, the results also support the hypothesis that animals may act as reservoirs of Y. enterocolitica for human infections in Brazil, an epidemiological aspect that has not been investigated in this country, confirming data from other parts of the world. INTRODUCTIONYersinia enterocolitica is the most prevalent Yersinia species connected to disease in humans (Bottone, 1999; RobinsBrowne, 2001). It has also frequently been isolated from animals, food and the environment (Fredriksson-Ahomaa et al., 1999;Thoerner et al., 2003; Falcão et al., 2004).Y. enterocolitica is responsible for gastroenteritis and other syndromes in humans and animals (Bottone, 1999 biochemical and serological tests that enable the differentiation of the strains into diverse bio-serotypes (Aleksic & Bockemühl, 1999). Also, pathogenic strains are related to some phenotypic characteristics, such as pyrazinamidase production, aesculin hydrolysis, salicin fermentation, calcium dependence, autoagglutination and Congo red absorption (Bottone, 1999). Molecular genetic studies have emphasized the importance of a virulence plasmid (pYV) that encodes various virulence genes, among them virF, which is an important transcriptional regulator of other plasmid genes, as well as the role of chromosomal virulence genes that mediate cell invasion (inv and ail) and produce a therm...

Infection of humans and animals caused by Salmonella is a major public health problem worldwide. Among the more than 2500 serovars, S. Infantis has been one of the 15 most isolated serovars in the world. Despite its clinical importance, little is known about the molecular characteristics of S. Infantis strains from Brazil. The aims of this study were to type S. Infantis isolates of this country and to assess their pathogenic potential. The molecular epidemiology of 35 S. Infantis strains, isolated from human sources (25) and food items (10) between 1984 and 2009 in São Paulo State, Brazil, were investigated using ERIC-PCR, PFGE and MLST. Furthermore, the presence of some virulence markers from Salmonella pathogenicity islands (SPIs) SPI-1 and SPI-2 and from the virulence plasmid was assessed by PCR. Using ERIC-PCR, 34 S. Infantis strains exhibited a high genetic similarity (≥ 93.7%) and using PFGE, 32 strains exhibited a similarity ≥ 80.6%. Additionally, MLST showed a high clonal similarity among strains that all presented the same ST32. Thirty-two isolates under investigation contained the virulence markers invA, sopB, sopD, sipA, sipD, ssaR, sifA, flgK, fljB and flgL. In conclusion, the S. Infantis strains studied were genetically similar, suggesting that a prevalent subtype has been causing disease and food contamination during a 25year period in São Paulo State, an important metropolitan region in Brazil. Furthermore, the contamination between strains from food items and sick humans indicates that better control measures for S. Infantis may be needed in this country.

Twenty-five extended-spectrum β-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.

Our study highlights the importance of molecular epidemiology in providing insight into the emergence, characteristics and distribution of STs among ESBL-producing K. pneumoniae.

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Carbapenem resistance among Acinetobacter baumannii strains isolated from clinical settings in Brazil has increased dramatically in the last 10 years due to the emergence and dissemination of OXA-type carbapenemase encoding genes. This study aimed to characterize the presence of carbapenem-hydrolyzing class D β-lactamases (CHDL)-encoding genes and clonal complexes playing a major role in the dissemination of OXA-carbapenemase-producing A. baumannii in Southeast Brazil. A total of 74 A. baumannii strains isolated from patients admitted to 4 hospitals in Southeast Brazil were analyzed. Molecular characterization of strains revealed that 67 strains carried blaOXA-23 (72%), blaOXA-143 (25%) or both genes (3%). PFGE analysis identified 12 PFGE clusters, grouping 26 pulsotypes. Two PFGE clusters were predominant, comprising more than 66% of OXA-producing A. baumannii isolates. Among 23 representative strains characterized by MLST-UO (Multilocus Sequence Typing Scheme - University of Oxford, http://pubmlst.org/abaumannii/), 14 different STs were identified, of which six were confirmed as novel sequence types (designated as STs 402-407). Most of these isolates belonged to clonal complexes CC104,CC109 or CC113, whereas three STs were singletons (ST339, 403 and 407). In conclusion, the presence of blaOXA-23- and blaOXA-143-like genes was not related to specific ST/CC, suggesting that the dissemination of OXA-carbapenemase-encoding genes may involve different STs, in which the spread of OXA-23-like is most likely due to mobile elements (i.e., plasmids). In this regard, CC104, CC109 and CC113 played a major role as predominant CDHL-carrying clones, instead of CC92, which was not identified.