Respiratory microbiota of healthy broilers can act as reservoirs for multidrug-resistant Escherichia coli

This study aimed at evaluate the presence and to study characteristics of Escherichia coli in the respiratory system microbiota of healthy broilers. Trachea, air sacs, and lungs of 20 broilers were analyzed at 21 days of age, reared in experimental conditions, without receiving antimicrobials. E. coli strains were isolated and identified using conventional bacteriology through morphological and biochemical characterization. The production of bacteriocin-like substances, the presence of virulence-associated genes (VAGs) of APEC (Avian Pathogenic Escherichia coli) predictors, and the antimicrobial susceptibility were evaluated. E. coli was found in 85 % of the animals (17/20), in the trachea, air sacs or lungs; and it was not found in 15 % of the animals (3/20). A total of 34 isolates were recovered, 13 from the air sacs, 13 from the lungs, and 8 from the trachea, which showed no production of bacteriocin-like substances nor virulence genes associated with APEC. Most isolates, 59 % (20/34), showed resistance to at least one of the tested antimicrobials, and six multiresistant strains were identified. The results demonstrated that strains of E. coli were commensal of the respiratory microbiota, and that they did not present pathogenicity to the host, since there were no clinical signs of disease, macroscopic lesions in the organs of the evaluated broilers, production of bacteriocin-like substances, nor virulence-associated genes considered as predictors of APEC in bacteria. These strains of E. coli were mostly susceptible to antimicrobials. However, the occurrence of multidrug-resistant strains suggests that these animals can act as reservoirs of resistant to antimicrobials E. coli.

Detection of ESBL/AmpC-Producing and Fosfomycin-Resistant Escherichia coli From Different Sources in Poultry Production in Southern Brazil

This study discussed the use of antimicrobials in the commercial chicken production system and the possible factors influencing the presence of Extended-spectrum β-lactamase (ESBL)/AmpC producers strains in the broiler production chain. The aim of this study was to perform longitudinal monitoring of ESBL-producing and fosfomycin-resistant Escherichia coli from poultry farms in southern Brazil (Paraná and Rio Grande do Sul states) and determine the possible critical points that may be reservoirs for these strains. Samples of poultry litter, cloacal swabs, poultry feed, water, and beetles (Alphitobius sp.) were collected during three distinct samplings. Phenotypic and genotypic tests were performed for characterization of antimicrobial resistant strains. A total of 117 strains were isolated and 78 (66%) were positive for ESBL production. The poultry litter presented ESBL positive strains in all three sampled periods, whereas the cloacal swab presented positive strains only from the second period. The poultry litter represents a significant risk factor mainly at the beginning poultry production (odds ratio 6.43, 95% confidence interval 1-41.21, p < 0.05). All beetles presented ESBL positive strains. The predominant gene was bla CTX-M group 2, which occurred in approximately 55% of the ESBL-producing E. coli. The cit gene was found in approximately 13% of the ESBL-producing E. coli as AmpC type determinants. A total of 19 out of 26 fosfomycin-resistant strains showed the fosA3 gene, all of which produced ESBL. The correlation between fosA3 and bla CTX-M group 1 (bla CTX-M55 ) genes was significant among ESBL-producing E. coli isolated from Paraná (OR 3.66, 95% CI 1.9-9.68) and these genetic determinants can be transmitted by conjugation to broiler chicken microbiota strains. Our data revealed that poultry litter and beetles were critical points during poultry production and the presence of fosfomycin-resistant strains indicate the possibility of risks associated with the use of this antimicrobial during production. Furthermore, the genetic determinants encoding CTX-M and fosA3 enzymes can be transferred to E. coli strains from broiler chicken microbiota, thereby creating a risk to public health.