PCR-based assays were developed for the detection of plasmid-and chromosome-borne virulence genes in Yersinia enterocolitica and Yersinia pseudotuberculosis, to investigate the distribution of these genes in isolates from various sources. The results of PCR genotyping, based on 5 virulence-associated genes of 140 strains of Y. enterocolitica, were compared to phenotypic tests, such as biotyping and serotyping, and to virulence plasmid-associated properties such as calcium-dependent growth at 37°C and Congo red uptake. The specificity of the PCR results was validated by hybridization. Genotyping data correlated well with biotype data, and most biotypes resulted in (nearly) homogeneous genotypes for the chromosomal virulence genes (ystA, ystB, and ail); however, plasmid-borne genes (yadA and virF) were detected with variable efficiency, due to heterogeneity within the bacterial population for the presence of the virulence plasmid. Of the virulence genes, only ystB was present in biotype 1A; however, within this biotype, pathogenic and apathogenic isolates could not be distinguished based on the detection of virulence genes. Forty Y. pseudotuberculosis isolates were tested by PCR for the presence of inv, yadA, and lcrF. All isolates were inv positive, and 88% of the isolates contained the virulence plasmid genes yadA and lcrF. In conclusion, this study shows that genotyping of Yersinia spp., based on both chromosome-and plasmid-borne virulence genes, is feasible and informative and can provide a rapid and reliable genotypic characterization of field isolates.Yersinia enterocolitica and Y. pseudotuberculosis, both members of the family Enterobacteriaceae, are comprised of strains with different degrees of pathogenicity. Both pathogenic and nonpathogenic strains are frequently isolated from various animals (birds, mammals, and reptiles) as well as from the environment (water and soil). Rodents (mice and rats), hares, rabbits, and birds serve as reservoirs for Y. pseudotuberculosis (1). Pathogenic strains of Y. enterocolitica and Y. pseudotuberculosis are frequently present in pigs without normally causing disease in these animals. Other food-producing animals, such as cattle, harbor mostly nonpathogenic strains of Y. enterocolitica.In humans, Y. enterocolitica and Y. pseudotuberculosis are well-known food-borne pathogens and are mainly transmitted through ingestion of contaminated pork, milk, or water. Yersiniosis frequently occurs in young children as enterocolitis with fever, diarrhea, and abdominal cramps. Although the disease is usually self-limiting, complications (e.g., septicemia) are not uncommon in immunocompromised hosts. Furthermore, sequelae, such as reactive arthritis, have been reported (21).The identification and further typing of subspecies, aiming at recognition of pathogenic strains of Yersinia spp., are traditionally based on phenotypic tests. Y. enterocolitica can be classified into biotype 1A, generally regarded as nonpathogenic (9), and the pathogenic biotypes 1B, 2, 3, 4, and 5. Both species ca...

Transmission of extended-spectrum β-lactamase (ESBL)–producing Enterobacteriaceae in households outweighs nosocomial dissemination in the non-outbreak setting. Importation of ESBL producers into the hospitals is as frequent as transmission during hospital stay. ESBL– Klebsiella pneumoniae might be more efficiently transmitted within the hospital than ESBL– Escherichia coli .

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The utility of quantitative Pneumocystis jirovecii PCR in clinical routine for diagnosing Pneumocystis pneumonia (PCP) in immunocompromised non-HIV patients is unknown.We analysed bronchoalveolar lavage fluid with real-time quantitative P. jirovecii PCR in 71 cases with definitive PCP defined by positive immunofluorescence (IF) tests and in 171 randomly selected patients with acute lung disease. In those patients, possible PCP cases were identified by using a novel standardised PCP probability algorithm and chart review. PCR performance was compared with IF testing, clinical judgment and the PCP probability algorithm.Quantitative

A review of the literature relating to the aetiopathogenesis, diagnosis and management of M microti infection in cats and dogs is included. This is supplemented with clinical and therapeutic experience gained from this case and other, unpublished cases managed over the past 15 years by one of the authors (DGM).