Antimicrobial Susceptibility and Minimum Inhibitory Concentration of <i>Salmonella enterica</i> Isolates from Chickens in Yobe State

Abstract

<i>Salmonella</i> of poultry are zoonotic microorganisms transmitted to humans and other animals via contact with infected poultry feces, meat, eggs and formites. This study was conducted to phenotypically characterize <i>Salmonella enterica</i> from samples collected from chickens presented for slaughter in some selected Local Government Areas of Yobe State, Nigeria, as well as carry out antimicrobial susceptibility and minimum inhibition concentration on the isolates. A cloacal swab and blood samples were collected and transported on ice pack to Veterinary Microbiology Laboratory, University of Maiduguri and analyzed for the presence of <i>Salmonella enterica</i>. Samples were then inoculated onto Xylose Lysine Deoxycholate agar for morphological identification of <i>Salmonella</i> blackish colonies. A total of 600 (300 cloacal swab and 300 blood), consisting (202 males, 98 female chickens, 150 local and exotic each) were randomly sampled in 16 weeks for the isolation of <i>Salmonella enterica</i>. The presumptive <i>Salmonella</i> isolates were further characterized using the Microbact<SUP>TM</SUP> GNB 24E System kit, with 40 randomly selected presumptive isolates (8 from blood and 32 from cloacal swab) tested using Microbact 24E GNB Computerize system, with 10 samples found to be positive for <i>Salmonella</i> organisms out of which 9 (22.5%) were from cloacal swab and 1 (2.5%) from blood. All the blood samples were tested for haemagglutination using slide method, 255 were found to be positive, where agglutination was observed. Where as only 8 (2.7%) were positives after blood culture 8 (2.67%). Exotic chickens showed the highest resistance level of (35%) to commonly used antibiotics (Amoxixillin and Ampicillin). The isolates from exotic chickens are susceptible to Ciprofloxacin 11 (68.8%), Ofloxacin 10 (62.5%), Gentamicin 2 (12.5%), Levofloxacin and Erythromycin 6 (37.5%), while intermediate to Norfloxacin 5 (31.3%) and Amoxicillin 7 (43.8%) but were resistant to Ampicillin 6 (37.5%%), Cefuroxime 10 (62.5%) and Amoxicillin 4 (25.0%). The MIC was carried out on all the 10 <i>Salmonella</i> isolated that showed positive on microbact 24E computerized system. All the 10 isolates from microbact 24E computerized system showed susceptibility to amoxicillin, ofloxacin, and ciprofloxacin on MIC. The MIC of ofloxacin and ciprofloxacin was distributed within 0.00175–2 µg/ml each, and for amoxilin, the MIC ranged between 0.00175-3.00 µg/ml. It is therefore, concluded that <i>Salmonella</i> organisms phenotypically characterized in the study area had antimicrobial susceptibility to routinely used antimicrobial drugs. As a result, it is suggested that the medications with high susceptibility be used to treat poultry salmonellosis in the study area.