Poultry as a vector for emerging multidrug resistant Enterococcus spp.: First report of vancomycin (van) and the chloramphenicol-florfenicol (cat-fex-cfr) resistance genes from pigeon and duck faeces

Abstract

Although commonly regarded as human and animal intestinal tract commensals, Enterococcus spp. have emerged as important nosocomial pathogens due to their intrinsic or acquired resistance to a number of antibiotics. Poultry has been suggested to be a reservoir for antibiotic resistance that may aggravate the problem of transmission of enterococci infections. Between January and December 2016, 106 Enterococcus spp. were isolated from a total of three poultry species. The collection included isolates recovered from chickens (n = 30), ducks (n = 35) and pigeons (n = 41). All enterococci isolates were screened for their ability to form biofilm. The antibiotic susceptibility was determined against 13 antibiotics using the disc diffusion method. The presence of the eight resistance genes, vanA, vanB, vanC, catA, catB, fexA, fexB and cfr was determined by PCR. All 106 isolates were resistant to clindamycin, whereas majority of isolates (>90%) were resistant to erythromycin, oxytetracycline, doxycycline, gentamycin, ciprofloxacin, norfloxacin, and vancomycin. All isolates produced biofilms and were classified as extensive drug-resistant. MAR_indices for all isolates was determined to be > 0.8, indicating that they have been recovered from high risk contamination sources. The cfr resistance gene was not detected in any of the 106 enterococci isolates, whereas the chloramphenicol resistance genes catA and catB were found in 18.9% (20/106) of the isolates. Interestengly, fexA 11.9% (15/106), fexB 8.7% (11/106), vanA 18.9% (20/106), vanB 25.5% (27/106), and vanC 33% (35/106) genes were also determined in our study. The present study highlights the emergence of a linezolid sensitive-vancomycin resistant enterococci, which lacks the cfr gene reporting also for the first time the detection of van, fex and cat -genes in Enterococcus species recovered from chickens, ducks and pigeons in Egypt suggesting that poultry species could be potential vectors for transmission of multidrug resistant enterococci posing a public health risk.

Keywords: Biofilm formation; Chicken; Chloramphenicol–florfenicol resistance genes; Duck; Enterococcus species; Pigeon; Vancomycin resistance genes.