Virulence Genes and Resistance Profile of Escherichia coli Isolated in Meat Meal Samples

Abstract

Background: Feed is the main route of transmission of pathogenic microorganisms and is responsible for a large part of the cost of poultry production, so the inclusion of alternative foods in diets for monogastrics has been a constant. Among alternative foods most used in modern poultry farming are animal meal, however, when contaminated they constitute a route of transmission of several pathogenic agents, including Escherichia coli. In addition, there is a zoonotic potential, as poultry products are intended for human consumption. The objective of this research was to detect virulence genes, as well as to evaluate the resistance profile of Escherichia coli isolates from meat meal samples.  

Materials, Methods & Results: A total of 40 Escherichia coli isolates were analyzed and the virulence genes surveyed iss, ompT, hlyF, iutA, and fimA identified by Polymerase Chain Reaction (PCR). The antimicrobial agents tested were: amoxycillin (30 μg), ceftiofur (30 μg), ciprofloxacin (5 μg), doxycycline (30 μg), florfenicol (30 μg), fosfomycin (200 μg), gentamicin (10 μg), norfloxacin (10 μg) and oxacillin (1 μg). It was possible to observe the occurrence of the iss resistance gene in 100% of Escherichia coli isolates, followed by hlyF (85%), fimA (75%), ompT (17.5%) and iutA (5%). Regarding the simultaneous detection for the genes, a greater association between the genes iss, hlyF and fimA (60%) was verified. All isolates showed resistance to oxacillin (100%), followed by doxycycline (25%), amoxicillin (22.5%), norfloxacin (17.5%), ceftiofur (15%), florfenicol (12.5%), fosfomycin (12.5%), ciprofloxacin (10%) and gentamycin (2.5%). In this study, a variation of the multiple antimicrobial resistance index (IRMA) was observed between 0.22 and 0.77. 

Discussion: The indiscriminate use of of antimicrobials as performance enhancers in production animals, may have contributed to the increase in antimicrobial resistance, with the occurrence of multiresistant Escherichia coli carrying virulence genes. Virulence genes present in Escherichia coli isolates are studied to understand the degree of influence they exert in the establishment of the disease, one of the most researched genes is the iss gene, involved in the processes that promote serum resistance. In this study, iss (100%) was present in all the isolates analyzed, although it is not the only mechanism used by these bacteria to reach internal organs and trigger an infection, this gene encodes an important mechanism associated with high levels of virulence. The second highest prevalence found was of the hlyF gene (85%), the high prevalence of hlyF suggests virulence potential, involved with the production of hemolysin and improvement of outer membrane vesicles associated with the release of toxins. The fimA gene (75%) was detected in a slightly lower percentage when compared to iss and hlyF. With the second lowest prevalence, the ompT gene (17.5%), is involved in a process that includes the proteolytic degradation of antimicrobial peptides and with the lowest prevalence the iutA gene (5%). Certain combinations of virulence genes make the strains easier to survive, adhere to, colonize and even the ability to develop septicemic conditions. Multiresistant E. coli strains, is a fact of concern for both animal and human health, since the presence of multiresistant strains, originating from poultry, can be transmitted from chicken carcasses.  In this sense, the importance of sanitary control of the inputs used in animal feed is emphasized, as well as the prudent use of antimicrobials in animal production, with a view to producing a safe food, minimizing not only the economic losses, but also the risks to human health. 

Keywords: antimicrobial, bacterial resistance, colibacillosis, poultry.