Comparative analysis of 16S rRNA based phylogeny, antibiotic susceptibility, and virulence traits of Arcobacter species recovered from domestic fowl and the Nile tilapia

Untreated poultry manure/droppings were used in integrated fish ponds as organic fertilizers. This process could put an additional complexity on the bacterial load within fish's ponds ecosystem. Arcobacter species is one of the most important food-borne zoonotic pathogens that infect humans, animals, fish, and fowl. This study aimed to examine if raw poultry manure could possibly enhance Arcobacter propagation among the cohabitant Nile tilapia. In addition, the comparative phenotypic and molecular characterizations among various Arcobacter spp. retrieved from two diverse animal hosts (the Nile tilapia and fowl) with special reference to antibiotic-resistant and virulence genes traits were also studied. Clinically, the examined Nile tilapias exhibited darkness, fin rot, and skin hemorrhages. Internally, the Nile tilapias displayed severe congestion in internal organs, catarrhal enteritis, and swollen gall bladder. The moribund chickens exhibited mild diarrhea, anorexia, and ruffled feathers. Internally, chickens displayed enlarged spleen and liver, enteritis, and kidney congestion. The bacterial colonies on Arcobacter selective agar appeared small and non-pigmented with an intact edge. The recovered bacterial isolates were identified as Arcobacter spp. depending on the phenotypic characters and PCR. Sequencing of 16S rRNA gene confirmed the identity of Arcobacter butzleri (A. butzleri), A. skirrowii, and A. cryaerophilus in both fish and fowl, while A. cloacae was confirmed in fish. PCR confirmed the occurrence of two virulence genes (pldA and tlyA) in most fish and chicken Arcobacter isolates. All chicken Arcobacter isolates showed resistance against ampicillin, ampicillin-sulbactam, and cefotaxime, and variable susceptibility to ciprofloxacin, aztreonam, imipenem, and amikacin. Fish Aeromonads were sensitive to ciprofloxacin, sulpha-trimethoprim, and amikacin.