Author(s)

Uzal Umar^1*, Umar Ahmed Faruk¹, Damoroem M. Tanko¹, Mohammed B. Yerima²

¹Department for Biological Sciences, Abubakar Tafawa Balewa University, Bauchi, Nigeria.
²Department of Microbiology, Federal University Dutse, Dutse, Nigeria.

β-Lactam antibiotics are a cornerstone in the treatment of bacterial infections on account of its high therapeutic index and selective toxicity—they act by inhibiting the biosynthesis of peptidoglycan, a key component in bacterial cell wall. Ninety (90) clinical specimens obtained from the microbiology unit Specialist Hospital Bauchi were screened for S. aureus, positive isolates were examined for β-Lactamase expression by using two Penicillin G concentrations (5000 IU/ml and 25,000 IU/ml) in acidometric agar technique with phenol red as indicator, and the susceptibility pattern of the isolates to β-Lactam antibiotics was also determined. S. aureus prevalence of 31% (28/90) was obtained, of which 96% (27/28) of strains were β-Lactamase positive in the standard test, while 63% (17/27) were able to hydrolyze penicillin G concentration of 25,000 IU/ml (5X the concentration in the standard test), and a strain was found to be β-Lactamase negative. The resistance to five β-Lactams, ampicillin, cephalexin, amoxicillin, cloxacillin and flucloxaillin, were 100%, 96%, 89%, 74% and 56% respectively. When ampicillin and amoxicillin were conjugated to β-Lactamase inhibitors sulbactam and clavulanic acid respectively the resistance to ampicillin decreased to 21% and to amoxicillin to 15%. The antibiotic susceptibility profile revealed β-Lactamase elaboration to be the major mechanism of resistance to the β-Lactams. β-Lactam utilization as therapeutic option would thus require the search for sensitive irreversible β-Lactamase inhibitors for the β-Lactamase enzymes or agents to block the release of β-Lactamase by strains.

β-Lactamase, Peptidoglycan, Transpeptidation, Haemolysis, Resistance, Antibiotics

Umar, U. , Faruk, U. , Tanko, D. and Yerima, M. (2016) Clinical Isolates of Staphylococcus aureus Show Variation in β-Lactamase Production and Are More Susceptible to Antibiotics Conjugated with β-Lactamase Inhibitors. Open Journal of Medical Microbiology, 6, 143-149. doi: 10.4236/ojmm.2016.64019.