A role for ColV plasmids in the evolution of pathogenic Escherichia coli ST58.

Escherichia coli ST58 has recently emerged as a globally disseminated uropathogen that often progresses to sepsis. Unlike most pandemic extra-intestinal pathogenic E. coli (ExPEC), which belong to pathogenic phylogroup B2, ST58 belongs to the environmental/commensal phylogroup B1. Here, we present a pan-genomic analysis of a global collection of 752 ST58 isolates from diverse sources. We identify a large ST58 sub-lineage characterized by near ubiquitous carriage of ColV plasmids, which carry genes encoding virulence factors, and by a distinct accessory genome including genes typical of the Yersiniabactin High Pathogenicity Island. This sub-lineage includes three-quarters of all ExPEC sequences in our study and has a broad host range, although poultry and porcine sources predominate. By contrast, strains isolated from cattle often lack ColV plasmids. Our data indicate that ColV plasmid acquisition contributed to the divergence of the major ST58 sub-lineage, and different sub-lineages inhabit poultry, swine and cattle.

Antimicrobial Resistance in Pasteurellaceae of Veterinary Origin.

Members of the highly heterogeneous family Pasteurellaceae cause a wide variety of diseases in humans and animals. Antimicrobial agents are the most powerful tools to control such infections. However, the acquisition of resistance genes, as well as the development of resistance-mediating mutations, significantly reduces the efficacy of the antimicrobial agents. This article gives a brief description of the role of selected members of the family Pasteurellaceae in animal infections and of the most recent data on the susceptibility status of such members. Moreover, a review of the current knowledge of the genetic basis of resistance to antimicrobial agents is included, with particular reference to resistance to tetracyclines, ß-lactam antibiotics, aminoglycosides/aminocyclitols, folate pathway inhibitors, macrolides, lincosamides, phenicols, and quinolones. This article focusses on the genera of veterinary importance for which sufficient data on antimicrobial susceptibility and the detection of resistance genes are currently available (Pasteurella, Mannheimia, Actinobacillus, Haemophilus, and Histophilus). Additionally, the role of plasmids, transposons, and integrative and conjugative elements in the spread of the resistance genes within and beyond the aforementioned genera is highlighted to provide insight into horizontal dissemination, coselection, and persistence of antimicrobial resistance genes. The article discusses the acquisition of diverse resistance genes by the selected Pasteurellaceae members from other Gram-negative or maybe even Gram-positive bacteria. Although the susceptibility status of these members still looks rather favorable, monitoring of their antimicrobial susceptibility is required for early detection of changes in the susceptibility status and the newly acquired/developed resistance mechanisms.

Detection and Genetic Environment of Pleuromutilin-Lincosamide-Streptogramin A Resistance Genes in Staphylococci Isolated from Pets.

Increasing emergence of staphylococci resistant to pleuromutilins, lincosamides, and streptogramin A (PLSA) and isolated from humans and pets is a growing public health concern worldwide. Currently, there was only one published study regarding one of the PLSA genes, vga(A) detected in staphylococci isolated from cat. In this study, eleven pleuromutilin-resistant staphylococci from pets and two from their owners were isolated and further characterized for their antimicrobial susceptibilities, plasmid profiles, genotypes, and genetic context of the PLSA resistance genes. The gene sal(A) identified in 11 staphylococcal isolates was found for the first time in Staphylococcus haemolyticus, Staphylococcus epidermidis, and Staphylococcus xylosus. Moreover, these 11 isolates shared the identical regions flanking the sal(A) gene located in the chromosomal DNA. Two S. haemolyticus isolates from a cat and its owner carried similar vga(A)LC plasmids and displayed indistinguishable PFGE patterns. A novel chromosomal multidrug resistance genomic island (MDRGI) containing 13 resistance genes, including lsa(E), was firstly identified in S. epidermidis. In addition, vga(A)LC, sal(A), and lsa(E) were for the first time identified in staphylococcal isolates originating from pet animals. The plasmids, chromosomal DNA region, and MDRGI associated with the PLSA resistance genes vga(A), vga(A)LC, sal(A), and lsa(E) are present in staphylococci isolated from pets and humans and present significant challenges for the clinical management of infections by limiting therapeutic options.

Diversity of class 1 and 2 integrons detected in Escherichia coli isolates from diseased and apparently healthy dogs.

Escherichia coli is one of the major pathogens causing urinary tract infections (UTIs) and pyometra in dogs. The aims of this study were to investigate canine E. coli isolates for the presence of class 1 and 2 integrons by PCR/sequencing and to characterize these isolates and their integron-carrying plasmids. Isolates were characterized by phylotyping, XbaI-macrorestriction analysis and plasmid transfer experiments. Plasmids were analyzed by S1 nuclease-PFGE, replicon typing, conjugation and restriction analysis. Antimicrobial resistance was investigated by antimicrobial susceptibility testing and PCR/sequencing. From 158 E. coli of dogs suffering from UTIs (n=51) and pyometra (n=52) or being apparently healthy (n=55), 13 isolates harboured class 1 (n=10) or class 2 integrons (n=3). They were distributed among the phylogenetic groups A (3/13), B1 (6/13), B2 (3/13) and D (1/13). Two isolates showed indistinguishable XbaI-patterns, but differed in the remaining characteristics. Another two isolates (UTI or apparently healthy) displayed different XbaI-patterns, but harboured similar plasmids. Integrons were found on plasmids of incompatibility groups IncF, IncF-IncFIC, IncFIB-IncHI2, IncFIB-IncN, IncFIC or IncHI2 and three of them were conjugative. Resistances to aminoglycosides, sulphonamides and trimethoprim were commonly detected. Class 1 integrons carried the gene cassette arrays dfrA12-orfF-aadA28, ΔdfrA17-aadA5, dfrA29, aadA7, aadA29 or dfrA12-orfF-aadA2-cmlA1-aadA1. Class 2 integrons carried the array dfrA1-sat2-aadA30. Two extended-spectrum ß-lactamase genes (blaCTX-M-2) and one AmpC ß-lactamase gene (blaCMY-2) were also detected on plasmids. These findings indicate the potential risk of the dissemination and persistence of E. coli and/or integron-carrying plasmids in companion animals.

Detection and characterization of extended-spectrum ß-lactamase-producing Escherichia coli from chicken production chains in Nigeria.

A total of 405 Escherichia coli from the chicken production chains in Nigeria were investigated for ESBL-production and 4 isolates were identified as ESBL producers. They were characterized by XbaI-PFGE, multilocus sequence typing (MLST), phylotyping, sequencing of porin and regulatory genes and of the regulatory region of chromosomal ampC genes. Transformed ESBL gene-carrying plasmids were characterized by S1-nuclease, replicon typing, conjugation, digestion and PCRs for detection of the genetic environment of ESBL genes. Susceptibility testing, PCRs for the resistance genes, integrons, and the DNA microarray were performed with both, the original isolates and the transformants. All ESBL-producing isolates harboured blaCTX-M-15 genes located on non-conjugative plasmids (120-155kb). Three isolates with closely related/indistinguishable XbaI-patterns belonged to phylogroup A, and MLST sequence type ST10 and the fourth to phylogroup D and ST405. Resistance to aminoglycosides, sulfonamides/trimethoprim, quinolones, and tetracyclines were seen in all isolates. Incompatibility group IncFIB blaCTX-M-15-carrying plasmids were detected in the three related isolates which carried also a class 1 integron (aadA2-orfF-dfrA12) and the resistance genes blaOXA-1, blaTEM-1, aac(3')-IIa, aac(6')-Ib-cr, sul1, sul2, and tet(A). The IncFIA-IncFIB-IncI1 blaCTX-M-15-carrying plasmid harboured additionally the resistance genes aac(3')-IIa and tet(B). The blaCTX-M-15 genes were associated with ISEcp1 and Δorf477. ESBL-producing isolates showed elevated MICs to cefoxitin (16-64mg/L) and ertapenem MICs (0.5-2.0mg/L) mainly due to alterations in the porin genes. The virulence genes astA and prfB were detected. Although a low prevalence of ESBL-producing isolates was found, co-located resistance genes on the ESBL gene-carrying plasmids may facilitate the dissemination of them.

The clonal spread of multidrug-resistant non-typhi Salmonella serotypes.

Non-typhoid Salmonella are one of the most important organisms causing food-borne diseases worldwide. There have been significant increases in developed countries in recent years in the occurrence of resistance, in particular multidrug resistance phenotypes, in non-typhoid Salmonella spp. Such increases have been observed in many countries, not only within the European community but also the Americas and Southeast Asia. Of particular concern is the increasing detection of Salmonella isolates displaying resistance to key antimicrobials, notably fluoroquinolones and third-generation cephalosporins. An important factor associated with this increase in multidrug resistance among particular Salmonella spp. is the national and international spread of certain clonal genotypes, the most recent being the global epidemic spread of multidrug-resistant S. Typhimurium DT104, since the early 1990s. In this review, we describe examples where particular antimicrobial-resistant Salmonella serotypes emerged, persisted for periods of time, and then quickly decreased in prevalence.

Detection of virulence genes in Salmonella Enteritidis isolated from different sources

A presença de três genes de virulência (invA, spvR e spvC) foi determinada em Salmonella Enteritidis isoladas de aves, suínos, humanos e alimentos. Todos os isolados foram positivos para o gene invA, 91,2% também foram positivos para o spvR e 90,2% para o spvC. Não existiu diferença significativa na prevalência dos genes de virulência entre isolados de diferentes origens. Os resultados indicaram que, provavelmente, exista um alto potencial de virulência nos isolados de S. Enteritidis caracterizados.

Detection of virulence genes in Salmonella Enteritidis isolated from different sources

The presence of three virulence genes, invA, spvR, and spvC, was determined in Salmonella Enteritidis isolated from poultry, pigs, humans and food. All isolates were positive for the invA gene, with 91.2% being positive for spvR and 90.2% for spvC. There was no significant difference in the prevalence of the virulence genes between isolates from different sources. The results indicate that there is a putative high virulence potential for the S. Enteritidis isolates characterized.

A presença de três genes de virulência (invA, spvR e spvC) foi determinada em Salmonella Enteritidis isoladas de aves, suínos, humanos e alimentos. Todos os isolados foram positivos para o gene invA, 91,2% também foram positivos para o spvR e 90,2% para o spvC. Não existiu diferença significativa na prevalência dos genes de virulência entre isolados de diferentes origens. Os resultados indicaram que, provavelmente, exista um alto potencial de virulência nos isolados de S. Enteritidis caracterizados.