ANTIBIOTICS SUSCEPTIBILITY STUDIES OF SOME BACTERIAL ISOLATES FROMPACKAGED MILK MARKETED IN ZARIA, NIGERIA

ANTIBIOTICS SUSCEPTIBILITY STUDIES OF SOME BACTERIAL ISOLATES FROMPACKAGED MILK MARKETED IN ZARIA, NIGERIA

ABSTRACT

Milk contamination with antibiotic resistant bacteria can be a major threat to public health, as the antibiotic resistant determinants can be transferred to other pathogenic bacteria potentially compromising the treatment of severe bacterial infections. This study was conducted to investigate the antibiotics susceptibility of bacterial isolates frompackaged milks marketed in Zaria. Two hundred packaged milk samples were bought from five locations (forty samples from each) in Zaria. Isolation and identification of the bacteria specieswere carried out using standard microbiological procedures. Antibiotics susceptibility of the isolates was determined using a panel of 12 antibiotics by disc diffusion method following Clinical Laboratory Standard Institute guidelines. Minimum Inhibitory Concentration (M.I.C.)was determined using agar plate dilution method.Conjugative studies were carried out with multiple antibiotics resistant isolates from milk samples. The resistant isolates were subjected to DNA isolation and agarose gel electrophoresis. The result obtained showed that the major contaminants of milk products analysed were Pseudomonas sppclosely followed by Enterobactersppand Escherichia coli and the overall contamination level of bacterial isolates in this study was 76.5%. One hundred and fifty-three bacterial isolates were identified from the milk sample, 27.5% were obtained from the first brand of milk sample, 21.6% from the second brand, 12.4% from the third brand and 38.6% from the fourth brand of milk samples. Susceptibility result showedthat high percentage of isolates were resistant to cloxacillin (99.35%), erythromycin (98%), amoxicillin (83.01%), chloramphenicol (83%) and tetracycline (81.7%) but were however susceptible to ofloxacin (99.3%) and gentamicin (83%). Multiple antibiotics resistance indices (MARI) showed that bacterial isolates from the studied packaged milk samples were multi-resistant with MARI ranging from 0.2 to 1.0. Out of ninety enterobacteriaceae studied, 93.3% of the bacterial isolates had MAR index of 0.3 and above.Conjugation studies revealed that nineteen out of twenty-six.

ANTIBIOTICS SUSCEPTIBILITY STUDIES OF SOME BACTERIAL ISOLATES FROMPACKAGED MILK MARKETED IN ZARIA, NIGERIA