Cefotaximase (CTX-M) and quinolone resistance genes (qnr) with additional antimicrobial resistance mechanisms in commensal Escherichia coli from healthy pigs

Concerning the importance of food producing animals as potential reservoirs of enteric bacteria with clinically relevant antimicrobial resistance traits, we tested the prevalence of extended-spectrum β-lactamase (ESBL)-producing and fluroquinolone resistant E. coli from pigs in order identify multiple resistance mechanisms circulating in pig farms in Hungary and Croatia with special regards to plasmid mediated genes encoding cefotaximases (CTX-M) and quinolone resistance (qnr). For this purpose, faecal samples were collected from pigs representing three farms from Hungary and six farms from Croatia with 45 and 60 samples respectively. Farms were located in separate regions of the countries. Cefotaxime or nalidixic acid resistance were used as prime markers for the isolation of multiresistant E. coli strains. A second selection was based on resistance to additional antimicrobials (i.e. gentamicin) aiming to reduce the collection to isolates with representative multiresistance phenotypes. In several cases more than two different multiresistance phenotypes have been isolated from the same pig, which were considered as independent E. coli isolates. This collection of multidrug resistant E. coli contained 139 strains and was tested for the presence of blaCTX-M and qnr genes by PCR. Selected isolates carrying genes blaCTX-M and/or qnr are being subjected for confirmation and further typing of antimicrobial resistance genes by using the PCR-microarray AMR05. Cefotaxim resistant E. coli have been detected in one Hungarian and one Croatian farm representing 17% of all pigs tested. In majority of the strains, the plasmid-related resistance phenotypes such as ampicillin, cefotaxim, gentamicin and tetracycline occurred in multiple combinations. In 11% of the strains the coexistence of Ctx-Nal phenotypes was detected, together with the presence of the cefotaximase gene blaCTX-M. E. coli strains with nalidixin resistance phenotype have been predominantly (70%) characterizing healthy pigs independently from the farm and country of isolation. Ciprofloxacin resistant strains occured on one farm only. The plasmid-mediated fluoroquinolone resistance gene qnrS was identified in 11% of the strains, with or without the nalidixin-ciprofloxacin resistant phenotype, while genes qnrA and qnrB were absent. Overall, our results lead to conclude that multiresistant commensal E. coli strains carrying plasmid-mediated CTX-M type cefotaximase and/or quinolone resistance genes in different combinations are widespread on some pig farms but much less on others, most likely reflecting differences in use of antimicrobials. Ama Szmolka is a holder of János Bolyai Stipend of the Hungarian Academy of Sciences

The extraordinary evolutionary history of the reticuloendotheliosis viruses

The reticuloendotheliosis viruses (REVs) comprise several closely related amphotropic retroviruses isolated from birds. These viruses exhibit several highly unusual characteristics that have not so far been adequately explained, including their extremely close relationship to mammalian retroviruses, and their presence as endogenous sequences within the genomes of certain large DNA viruses. We present evidence for an iatrogenic origin of REVs that accounts for these phenomena. Firstly, we identify endogenous retroviral fossils in mammalian genomes that share a unique recombinant structure with REVs—unequivocally demonstrating that REVs derive directly from mammalian retroviruses. Secondly, through sequencing of archived REV isolates, we confirm that contaminated Plasmodium lophurae stocks have been the source of multiple REV outbreaks in experimentally infected birds. Finally, we show that both phylogenetic and historical evidence support a scenario wherein REVs originated as mammalian retroviruses that were accidentally introduced into avian hosts in the late 1930s, during experimental studies of P. lophurae, and subsequently integrated into the fowlpox virus (FWPV) and gallid herpesvirus type 2 (GHV-2) genomes, generating recombinant DNA viruses that now circulate in wild birds and poultry. Our findings provide a novel perspective on the origin and evolution of REV, and indicate that horizontal gene transfer between virus families can expand the impact of iatrogenic transmission events

Chlamydial infections in feral pigeons in Europe: review of data and focus on public health implications

Feral pigeons (Columba livia domestica), which thrive in most European towns and cities, are commonly infected with the zoonotic bacterium Chlamydophila psittaci, the agent of psittacosis (also known as ornithosis) in humans. A number of surveys carried out over the last thirty years across Europe have detected high seropositivity values and high percentages of infection in feral pigeon populations. Overall, when considering data from 11 European countries, seropositivity values to C. psittaci in the sampled populations ranged from 19.4% to 95.6%. In most surveys, the complement fixation test was used, and antibodies were detected in 19.4\u201366.3% of the samples, with a median of 46.1%. Indirect immunofluorescence and ELISA tests were employed less frequently, but led to the detection of higher percentages of seropositivity (23.7\u201367.7% and 35.9\u201395.6%, respectively). Attempts to grow C. psittaci in cell culture or embryonated chicken eggs were successful in 2\u201342.3% and 0\u201357.1% of samples, respectively, antigen detection methods were positive in 2.3\u201340% of samples, while conventional PCR and real-time PCR using different genomic targets detected the organism in 3.4\u201350% of samples. Twenty-five C. psittaci isolates from pigeons were typed as ompA genotype B (n = 14), E (n = 10) and E/B (n = 1). The huge increase of feral pigeon populations in Europe is a major cause of concern for the detrimental effect of pigeon droppings on environmental hygiene, in addition to the extensive damage due to the fouling of buildings and monuments. The most important pathogenic organism transmissible from feral pigeons to humans is C. psittaci, with 101 cases of disease reported in the literature. Exposure to C. psittaci-contaminated dust, direct contact with pigeons through handling and, to a lesser extent, through pigeon feeding have been identified as hazardous exposures in more than half of the human cases, while loose or transient contacts with feral pigeons have been mentioned in about 40% of the cases

Chlamydia infections in feral pigeons in Europe : review of data and focus on public health implications

International audienc

European validation of Real-Time PCR method for detection of Salmonella spp. in pork meat

The classical microbiological method for detection of Salmonella spp. requires more than five days for final confirmation, and consequently there is a need for an alternative methodology for detection of this pathogen particularly in those food categories with a short shelf-life. This study presents an international (at European level) ISO 16140-based validation study of a non-proprietary Real-Time PCR-based method that can generate final results the day following sample analysis. It is based on an ISO compatible enrichment coupled to an easy and inexpensive DNA extraction and a consolidated Real-Time PCR assay. Thirteen laboratories from seven European Countries participated to this trial, and pork meat was selected as food model. The limit of detection observed was down to 10CFU per 25g of sample, showing excellent concordance and accordance values between samples and laboratories (100%). In addition, excellent values were obtained for relative accuracy, specificity and sensitivity (100%) when the results obtained for the Real-Time PCR-based methods were compared to those of the ISO 6579:2002 standard method. The results of this international trial demonstrate that the evaluated Real-Time PCR-based method represents an excellent alternative to the ISO standard. In fact, it shows an equal and solid performance as well as it reduces dramatically the extent of the analytical process, and can be easily implemented routinely by the Competent Authorities and Food Industry laboratories