Extended-spectrum β-lactamase-producing and AmpC-producing Escherichia coli from livestock and companion animals, and their putative impact on public health: a global perspective

AbstractThe possible zoonotic spread of antimicrobial-resistant bacteria is controversial. This review discusses global molecular epidemiological data combining both analyses of the chromosomal background, using multilocus sequence typing (MLST), and analyses of plasmid (episomal) extended-spectrum β-lactamase (ESBL)/AmpC genes in Escherichia coli present in humans and animals. For consideration of major epidemiological differences, animals were separated into livestock and companion animals. MLST revealed the existence of ESBL-producing isolates thoughout the E. coli population, with no obvious association with any ancestral EcoR group. A similar distribution of major ESBL/AmpC types was apparent only in human isolates, regardless of their geographical origin from Europe, Asia, or the Americas, whereas in animals this varied extensively between animal groups and across different geographical areas. In contrast to the diversity of episomal ESBL/AmpC types, isolates from human and animals mainly shared identical sequence types (STs), suggesting transmission or parallel micro-evolution. In conclusion, the opinion that animal ESBL-producing E. coli is a major source of human infections is oversimplified, and neglects a highly complex scenario

Knock-in mice expressing a 15-lipoxygenating Alox5 mutant respond differently to experimental inflammation than reported mice

Arachidonic acid 5-lipoxygenase (ALOX5) is the key enzyme in the biosynthesis of pro-inflammatory leukotrienes. We recently created knock-in mice (Alox5-KI) which express an arachidonic acid 15-lipoxygenating Alox5 mutant instead of the 5-lipoxygenating wildtype enzyme. These mice were leukotriene deficient but exhibited an elevated linoleic acid oxygenase activity. Here we characterized the polyenoic fatty acid metabolism of these mice in more detail and tested the animals in three different experimental inflammation models. In experimental autoimmune encephalomyelitis (EAE), Alox5-KI mice displayed an earlier disease onset and a significantly higher cumulative incidence rate than wildtype controls but the clinical score kinetics were not significantly different. In dextran sodium sulfate-induced colitis (DSS) and in the chronic constriction nerve injury model (CCI), Alox5-KI mice performed like wildtype controls with similar genetic background. These results were somewhat surprising since in previous loss-of-function studies targeting leukotriene biosynthesis (Alox5(-/-) mice, inhibitor studies), more severe inflammatory symptoms were observed in the EAE model but the degree of inflammation in DSS colitis was attenuated. Taken together, our data indicate that these mutant Alox5-KI mice respond differently in two models of experimental inflammation than Alox5(-/-) animals tested previously in similar experimental setups

Specific TaqMan Probes for the Identification and Quantification of Lactobacilli in Pharmaceuticals

Several probiotic products containing species of the genus Lactobacillus are available on the market. Usually, these are fermented dairy products such as yoghurts and vegetables. Additionally, probiotic bacteria are used in pharmaceuticals, which are also believed to have beneficial effects on human health. Common pharmaceutical application forms to deliver probiotics are tablets, drops or granulate formulations for oral administration. They should contain sufficient numbers of viable probiotics to assure active health benefits. Despite the successful commercialization of lactobacilli, their traditional species identification methods are time-consuming and laborintensive and do not allow quantification of the species. Therefore, the objective of the present work was to develop a culture independent, fast identification and quantification method for two commercially important species of the genus Lactobacillus (L. acidophilus and L. reuteri). We used a TaqMan® real time PCR assay based on the GroEL heat shock protein region. Therefore universal lactobacilli primers and species-specific TaqMan® primers have been developed. The assay allowed an unambiguous species-specific detection of L. acidophilus and L. reuteri from bacterial cultures as well as directly from tablets. Using this assay, we were able to detect lactobacilli strains to a level of 104 cfu/ml, which is a sufficient detection limit as commercial pharmaceuticals usually contain 108–1010 cfu/ tablet of probiotic strains

Isolation and Characterization of Intestinal Escherichia coli Clones from Wild Boars in Germany

Jörg Jores is ILRI authorOur understanding of the composition of Escherichia coli populations in wild boars is very limited. In order to obtain insight into the E. coli microflora of wild boars, we studied E. coli isolates from the jejunums, ileums, and colons of 21 wild boars hunted in five geographic locations in Germany. Ten isolates per section were subjected to clonal determination using pulsed-field gel electrophoresis. One representative isolate per clone was further investigated for virulence traits, phylogenetic affiliation, and antimicrobial susceptibility. Macrorestriction analysis of 620 isolates revealed a range of clone diversity among the sections and animals, with up to 9 and 16 different clones per section and animal, respectively. Most of the clones for a given animal were shared between two adjacent intestinal sections. The overall highest clonal diversity was observed within the colon. While the astA gene was present in a large number of clones, other virulence genes and hemolytic ability were detected only sporadically. Clones of all four ECOR groups dominated the intestinal sections. Phylogenetic analysis and the occurrence of virulence genes correlated with the isolation frequencies for clones. All E. coli clones from wild boars were susceptible to all antimicrobial agents tested. In conclusion, though several parameters (including an animal-specific and highly diverse E. coli clone composition, the simultaneous occurrence of single clones in two adjacent intestinal sections of a given animal, and a higher E. coli diversity in the large intestine than in the small intestine) of E. coli populations of wild boars were similar to those of previously described E. coli populations of conventionally reared domestic pigs, our data also indicate possible differences, as seen for the E. coli diversity in the large intestine, the occurrence of certain virulence genes and phylogenetic groups, and antimicrobial susceptibilities

Phenotypic zinc resistance does not correlate with antimicrobial multi-resistance in fecal E. coli isolates of piglets

Background: Following the ban on antimicrobial usage for growth promotion in animal husbandry in the EU, nonantimicrobial agents including heavy metal ions (e.g. zinc and copper), prebiotics or probiotics have been suggested as alternatives. Zinc has extensively been used in pig farming, particularly during weaning of piglets to improve animal health and growth rates. Recent studies, however, have suggested that high dietary zinc feeding during weaning of piglets increases the proportion of multi-drug resistant E. coli in the gut, contraindicating the appropriateness of zinc as an alternative. The underlying mechanisms of zinc effects on resistant bacteria remains unclear, but coselection processes could be involved. In this study, we determined whether E. coli isolates from intestinal contents of piglets that had been supplemented with high concentrations of zinc acquired a higher tolerance towards zinc, and whether multi-drug resistant isolates tolerated higher zinc concentrations. In addition, we compared phenotypic zinc and copper resistance of E. coli isolates for possible correlation between phenotypic resistance/tolerance to different bivalent ionic metals. Results: We screened phenotypic zinc/copper tolerance of 210 isolates (including antimicrobial resistant, multi-drug resistant, and non-resistant E. coli) selected from two, independent zinc-feeding animal trials by determining a zinc/ copper minimal inhibitory concentration (Merlin, Bornheim-Hersel, Germany). In both trials, groups of piglets were supplemented either with high dietary zinc (> 2000 ppm) or control (50–70 ppm, background) concentrations. Our observations showed that high concentration zinc exposure did not have an effect on either zinc or copper phenotypic tolerance of E. coli isolates from the animals. No significant association was found between antimicrobial resistance and phenotypic zinc/copper tolerance of the same isolates. Conclusion: Our findings argue against a co-selection mechanism of antimicrobial drug-resistance and zinc tolerance after dietary zinc supplementation in weaning piglets. An explanation for an increase in multi-drug resistant isolates from piglets with high zinc dietary feeding could be that resistant bacteria to antimicrobial agents are more persistent to stresses such as zinc or copper exposure.Peer Reviewe

A new multilocus sequence typing scheme for the genotypic characterization of Streptococcus canis isolated from human and animal sources.

Our aim was to develop a new multilocus sequence typing (MLST) scheme for Streptococcus canis. We also wanted to compare isolates recovered from different hosts, mainly house pets and humans, in order to define the clonal structure of the S. canis population and explore the zoonotic potential of distinct S. canis genetic lineages. Eighty-five S. canis isolates recovered from infections in animals (n = 78, recovered from 2000 to 2010 in three European countries, mainly from house pets) and humans (n = 7, recovered from 2006 to 2010 in Portugal) were studied. Isolates were identified by API 20 Strep, 23S rRNA gene targeted PCR and 16S rRNA gene sequencing, and characterized by MLST, pulsed-field gel electrophoresis (PFGE) and emm typing. All isolates were successfully typed with the proposed MLST scheme, indicating its applicability to S. canis from distinct sources. The MLST analysis showed a polyclonal structure of the S. canis population, where the same genetic lineages are found infecting house pets and humans and are disseminated in distinct geographic locations. PFGE confirmed the MLST findings, as it identified the same prevailing lineages and further strengthened the similarity between animal and human isolates. Phylogenetic analysis conducted with the 16S rRNA and MLST loci sequence data indicated that S. canis was a divergent taxon of the sister species Streptococcus pyogenes and Streptococcus dysgalactiae subsp. equisimilis, and found evidence of acquisition of genetic material by S. canis from the latter species. The presence of emm-like genes was restricted to a few isolates and correlated with MLST defined genetic lineages. Our data shows that S. canis isolated from house pets and humans are a single population and demonstrates that isolates belonging to the main genetic lineages identified are able to infect the human host, providing strong evidence for the zoonotic nature of S. canis infection in humans. A MLST database for S. canis was established at http://pubmlst.org/scanis/ (hosted by the Department of Zoology, University of Oxford, United Kingdom), constituting a valuable tool for future studies on the molecular epidemiology of this pathogen

Bacterial zoonoses transmitted by Household pets: State of the Art and Future perspectives for targeted research and policy actions

The close contact between household pets and people offers favourable conditions for bacterial transmission. In this article, the aetiology, prevalence, transmission, impact on human health and preventative measures are summarized for selected bacterial zoonoses transmissible by household pets. Six zoonoses representing distinct transmission routes were selected arbitrarily based on the available information on incidence and severity of pet-associated disease caused by zoonotic bacteria: bite infections and cat scratch disease (physical injuries), psittacosis (inhalation), leptospirosis (contact with urine), and campylobacteriosis and salmonellosis (faecal–oral ingestion). Antimicrobial resistance was also included due to the recent emergence of multidrug-resistant bacteria of zoonotic potential in dogs and cats. There is a general lack of data on pathogen prevalence in the relevant pet population and on the incidence of human infections attributable to pets. In order to address these gaps in knowledge, and to minimize the risk of human infection, actions at several levels are recommended, including: (1) coordinated surveillance of zoonotic pathogens and antimicrobial resistance in household pets, (2) studies to estimate the burden of human disease attributable to pets and to identify risk behaviours facilitating transmission, and (3) education of those in charge of pets, animal caretakers, veterinarians and human medical healthcare practitioners on the potential zoonotic risks associated with exposure to pets. Disease-specific recommendations include incentives to undertake research aimed at the development of new diagnostic tests, veterinary-specific antimicrobial products and vaccines, as well as initiatives to promote best practices in veterinary diagnostic laboratories and prudent antimicrobial usage

Species differentiation within the Staphylococcus intermedius group using a refined MALDI-TOF MS database

AbstractAmong coagulase-positive staphylococci of animal origin, the members of the Staphylococcus intermedius-group (SIG: S. intermedius, Staphylococcus pseudintermedius and Staphylococcus delphini) are important opportunistic pathogens in different animal hosts and occasionally in humans. However, the unambiguous species diagnosis of SIG is often challenging. Therefore, matrix-assisted laser desorption ionization—time of flight mass spectrometry (MALDI-TOF MS) -based SIG-identification with Bruker Microflex LT in combination with Biotyper 3.0 software (Bruker Daltonics, Bremen, Germany) was evaluated using (i) the original database content and (ii) the database after extension with distinct hierarchical clustered reference spectra for 60 SIG. A convenience sample comprising 200 isolates was used to compare both database performances. As a result, 17 isolates initially diagnosed as S. intermedius with the current content of the Bruker database were identified as S. pseudintermedius by applying the in-house reference spectra extended version. Furthermore, a significant improvement (average rise of log score value: 0.24) of the SIG identification score values was achieved, emphasizing that further sequence-based refinement of the Bruker database content allows improvement of MALDI-TOF MS-based identification