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Patterns of antibiotics susceptibility of isolates and plasmid analysis of Staphylococcus from surgical site infections in Nigeria
Abstract
There has been a significant increase in resistance of common bacterial isolates from surgical site infections in our community resulting in prolonged hospital stay, disability and deaths of patients. In this vein,
we surveyed the antibiotic susceptibility profiles of aerobic bacterial isolates from postoperative wound infections and determined whether resistance in Staphylococcus aureus was genetically mediated. A total of 161 isolates were obtained from 153 swab samples of infected wounds using cultural, morphological, and biochemical characteristics. The predominant bacterial isolates were: S. aureus (53.4%), Escherichia coli (23.0%), Staphylococcus epidermidis (11.2%), Pseudomonas aeruginosa (5.0%), and species of Klebsiella and Proteus 3.7% each. On the whole: Escherichia coli, Klebsiella and Proteus showed similar antibiotic susceptibility patterns viz: 66.7-100% for ciprofloxacin, 66.7-100% gentamicin and 50-80% augmentin; and less than 50% for amoxacillin, erythromycin, tetracycline, cotrimoxazole, cloxacillin and chloramphenicol. S. aureus showed percentage susceptibility of 50-100% and Staphylococcus epidermidis (50-100%) for cloxacillin and augmentin, and less than 60% for amoxacillin, erythromycin, tetracycline, cotrimoxazole, gentamicin and chloramphenicol. Multi drug resistance (MDR) of S. aureus strains to at least three classes of the antibiotics used was about 70.5%. Four out of the 11 MDR S. aureus strains were found to harbor plasmids
with varying molecular weights that ranged from 3.114 to 6.509 kb. One of the multi-drug resistant isolates still exhibited resistance even after curing. This showed that other genetic elements may also be involved in the
acquisition of these forms of resistance other than plasmid elements.
Key Words: Postoperative –Wounds-Aerobic bacteria-Staphylococcus aureus.
we surveyed the antibiotic susceptibility profiles of aerobic bacterial isolates from postoperative wound infections and determined whether resistance in Staphylococcus aureus was genetically mediated. A total of 161 isolates were obtained from 153 swab samples of infected wounds using cultural, morphological, and biochemical characteristics. The predominant bacterial isolates were: S. aureus (53.4%), Escherichia coli (23.0%), Staphylococcus epidermidis (11.2%), Pseudomonas aeruginosa (5.0%), and species of Klebsiella and Proteus 3.7% each. On the whole: Escherichia coli, Klebsiella and Proteus showed similar antibiotic susceptibility patterns viz: 66.7-100% for ciprofloxacin, 66.7-100% gentamicin and 50-80% augmentin; and less than 50% for amoxacillin, erythromycin, tetracycline, cotrimoxazole, cloxacillin and chloramphenicol. S. aureus showed percentage susceptibility of 50-100% and Staphylococcus epidermidis (50-100%) for cloxacillin and augmentin, and less than 60% for amoxacillin, erythromycin, tetracycline, cotrimoxazole, gentamicin and chloramphenicol. Multi drug resistance (MDR) of S. aureus strains to at least three classes of the antibiotics used was about 70.5%. Four out of the 11 MDR S. aureus strains were found to harbor plasmids
with varying molecular weights that ranged from 3.114 to 6.509 kb. One of the multi-drug resistant isolates still exhibited resistance even after curing. This showed that other genetic elements may also be involved in the
acquisition of these forms of resistance other than plasmid elements.
Key Words: Postoperative –Wounds-Aerobic bacteria-Staphylococcus aureus.