Isolation and antibiotic susceptibility of bacteria from milk of apparently healthy goats in Abeokuta, Ogun State, Nigeria

Abstract

Milk contaminated with antibiotic resistant bacteria can be a major threat to public health. This study wasconducted toinvestigate the antibiotic susceptibility of bacterial isolates from goat's milk in Abeokuta. Nine (9) bacteria species comprising 182 isolates were identified in 73 milk samples collected from six (6) different places located some 2 - 50 kilometers apart in Abeokuta. Isolation and identification of the bacteria species were carried out using standard microbiological procedures. The bacteria species were Pseudomonas spp (22.28%), Micrococcus spp (21.74%), Staphylococcus aureus (19.02%), Staphylococcus saprophyticus (15.22%), Enterobacter spp (8.70%), Bacillus spp (5.43%), Pasteurella spp (4.89%), Escherichia coli (2.17%), and Citrobacter spp (0.54%). Antibiotic susceptibility of the isolates and minimum inhibitory concentration were determined using a panel of 10 antibiotics by disc diffusion method and standard guidelines. The bacterial load from milk samples obtained in various locations are as follows:-DUFARMS,0.1-1.2x10 cfu/mL;Eweje, 0.6-1.2x10 cfu/mL; Odeda, 0.6-3.5x10 cfu/mL; Elite, 1.0-5.5x10 cfu/mL; Elega, 0.1- 2.52x10 cfu/mL; and Obantoko 0.16-1.04x10 cfu/mL. The mean counts were 0.54 ± 0.40x10 cfu/mL; 0.78 ±0.13x10 cfu/mL; 1.83±1.23x10 cfu/mL; 2.58 ±1.45x10 cfu/mL; 8.51 ±5.60x10 cfu/mL and 4.14 ±3.90 x10 cfu/mL respectively. Antibiotic susceptibility results showed that the organisms were 100% resistant to Amoxicillin,86.26% to Ceftriazone, 84.62% to Streptomycin, 82.42% to Chloramphenicol and 78.02% to Cotrimoxazol. However, the isolates were only 6.04% resistant to Ofloxacin and 11.54% to Pefloxacin suggesting that these might just be the only two antibiotics that the pathogens might respond to. In conclusion, microbes that are ordinarily commensals may be highly resistant to commonly used Antibiotics. This could pose serious problems in managing outbreaks associated these microbes. Reservoirs for bacterial resistance may be present in healthy animal populations and research is needed to accurately quantify the problem, propose and evaluate practicable solutions. There is the need to clarify the role of environmental factors, agents, and transmission of bacterial resistance in apparently healthy livestock.