Diversity and antibiotic susceptibility of bacteria in the gastrointestinal tract and skin of house wall geckos (Hemidactylus frenatus)

Abstract

Animals maintain complex relationships with diverse microorganisms living in their gastrointestinal tracts (GIT) and skin as normal flora. This work investigated the bacterial composition of the GIT and skin of house wall geckos (Hemidactylus frenatus) and their susceptibility to antibiotics. The samples were captured from residential areas in Oworo, Lagos and cultured on different nutrient media. The isolates were biochemically identified and subjected to susceptibility tests using the Kirby-Bauer disk diffusion method. Seventy-one (71) bacteria species were isolated from both GIT and skin of 20 geckos (8 males and 12 females). They belong to 14 genera.; Staphylococci, Bacillus, Listeria, Corynebacterium, Shigella, Yersinia, Klebsiella, Pseudomonas, Salmonella, Serratia, Enterobacter, Citrobacter, Escherichia and Proteus. Staphylococcus spp. (33.79%) were the most prevalent followed by Pseudomonas spp. (15.45%) and Salmonella spp. (9.86%). The bacterial population was higher in male (56%) than the female (44%) geckos, and in the GIT (63%) than on the skin (37%). The Gram-positive isolates were a 100% resistant to Gentamicin (30 µg/disc), Oxacillin (1 µg/disc) and Vancomycin (30 µg/disc). They were susceptible to Chloramphenicol (30 µg/disc) (54.5%) and Doxycycline (30 µg/disc) (66.67%). There was a 100% resistance in Gram-negative bacteria to Aztreonam (30 µg/disc), Cefotaxime (30 µg/disc) and Rifampicin (5 µg/disc), with a 100% sensitivity to Meropenem (10 µg/disc). According to the findings, the gastrointestinal tract harbours more bacteria than the skin of geckos and both are reservoirs of pathogenic bacteria.