Commentary: Comparative Analysis of Phylogenetic Assignment of Human and Avian ExPEC and Fecal Commensal Escherichia coli Using the (Previous and Revised) Clermont Phylogenetic Typing Methods and its Impact on Avian Pathogenic Escherichia coli (APEC) Classification

Virulence potential of antimicrobial-resistant extraintestinal pathogenic Escherichia coli from retail poultry meat in a Caenorhabditis elegans model

Healthy poultry can be a reservoir for extraintestinal pathogenic Escherichia coli (ExPEC), some of which could be multidrug resistant to antimicrobials. These ExPEC strains could contaminate the environment and/or food chain representing thus, food safety and human health risk. However, few studies have shown the virulence of poultry-source antimicrobial-resistant (AMR) ExPEC in humans. This study characterized AMR ExPEC and investigated the virulence potential of some of their isolates in a Caenorhabditis elegans infection model. A total of 46 E. coli isolates from poultry (chicken, n = 29; turkey, n = 12) retail meats and chicken feces (n = 4), or humans (n = 1) were sequenced and identified as ExPEC. Except eight, all remaining 38 ExPEC isolates were resistant to at least one antibiotic and carried corresponding antimicrobial resistance genes (ARGs). About 27 of the 46 ExPEC isolates were multidrug-resistant (≥3 antibiotic classes). Seven ExPEC isolates from chicken or turkey meats were of serotype O25:H4 and sequence type (ST) 131 which clustered with an isolate from a human urinary tract infection (UTI) case having the same serotype and ST. The C. elegans challenge model using eight of studied ExPEC isolates harboring various ARGs and virulence genes (VGs) showed that regardless of their ARG or VG numbers in tested poultry meat and feces, ExPEC significantly reduced the life span of the nematode (P < 0.05) similarly to a human UTI isolate. This study indicated the pathogenic potential of AMR ExPEC from retail poultry meat or feces, but more studies are warranted to establish their virulence in poultry and human. Furthermore, relationships between specific resistance profiles and/or VGs in these E. coli isolates for their pathogenicity deserve investigations.

Autogenous Escherichia coli Vaccine Application as an Innovative Antimicrobial Therapy in Poultry Farming-A Case Report

Escherichia coli (E. coli) is one of the most common bacterial causes of infection in poultry farming. Whether the infection is localized or systemic, a primary or secondary disease, it is most frequently treated through the application of wide-spectrum antimicrobials. Excessive use of antimicrobials in agriculture is significantly contributing to the worldwide rise of antimicrobial resistance, but is also very expensive and often ineffective in the long term. Here, we present a case where a colibacillosis outbreak on a family farm of laying hens was treated using an autogenous vaccine. The birds had septicemia, cellulitis, and severe skin wounds. They were not vaccinated against E. coli, and did not receive any antimicrobials previously. E. coli strains were isolated from the daily mortalities on the farm and used for preparation of the vaccine. Each bird was given an intramuscular injection of the autogenous vaccine. The immunogenicity of the vaccine was tested by the determination of specific antibody levels in the sera of the birds using the in-house ELISA. Shortly after vaccination, the morbidity and mortality rates significantly decreased, and egg production was improved. The application of the autogenous vaccine served as a curative and preventive measure, and has proven to be a very efficient method of antimicrobial therapy.

An Integrated Perspective on Virulence-Associated Genes (VAGs), Antimicrobial Resistance (AMR), and Phylogenetic Clusters of Pathogenic and Non-pathogenic Avian Escherichia coli

Avian pathogenic Escherichia coli (APEC) is an important bacterial pathogen that causes avian colibacillosis and leads to huge economic losses in the poultry industry. Different virulence traits contribute to pathogenesis of APEC infections, and antimicrobial resistance (AMR) has also been an overwhelming issue in poultry worldwide. In the present study, we aimed to investigate and compare the presence of virulence-associated genes (VAGs), AMR, and phylogenetic group's distribution among APEC and avian fecal E. coli (AFEC) strains. E. coli from birds with colisepticemia and yolk sac infection (YSI) (APEC) plus E. coli strains from the feces of healthy birds (AFEC) were compared by the aforementioned traits. In addition, the clonal relatedness was compared using Enterobacterial repetitive intergenic consensus PCR (ERIC-PCR). Although all strains were susceptible to fosfomycin, ceftriaxone, and cefixime, almost all strains (98%) were multi-drug resistant (MDR). All strains (except two) harbored at least three or more VAGs, and the virulence scores tended to be higher in pathogenic strains especially in the colisepticemic group. All phylogenetic groups were found in isolates from YSI, colisepticemia, and the feces of healthy birds; however, the frequency of phylogroups varied according to the source of the isolate. B1 and C phylogroups were statistically more likely to be found among APEC from YSI and colisepticemic E. coli groups, respectively, while phylogroup A was the most frequently occurring phylogroup among AFEC strains. Our findings also revealed that AMR and VAGs are not essentially co-evolved traits as in some instances AMR strains were more prevalent among AFEC. This reflects the divergent evolutionary pathways of resistance acquisition in pathogenic or non-pathogenic avian E. coli strains. Importantly, strains related to phylogenetic group C showed higher virulence score and AMR that requires further attention. To some extent, ERIC-PCR was able to group strains by isolation source, phylogroup, or virulence genes. Further integrated studies along with assessment of more detailed genotypic and phenotypic features could potentially lead to better understanding of virulence, resistance, and evolution of ExPEC.