Isolation and Antibiogram of Staphylococcus aureus from Patients Admitted at Specialist Hospital Okitipupa, Ondo State, Nigeria

Aims: To isolate and determine the antimicrobial resistance and susceptibilities of Staphylococcus aureus from patients hospitalized at State Specialist Hospital, Okitipupa, Ondo State, Nigeria.

Study Design: Prospective cross sectional.

Place and Duration of Study: Department of Biological Sciences, Ondo State University of Science and Technology, Okitipupa, between March and April 2015.

Methodology: Forty three (43) samples were obtained from nasal cavity, skin, wound, or umbilical cord of 20 patients aged 4 days to 80 years. Isolates were identified by cultural characteristics on Mannitol Salt Agar, Nutrient agar and biochemical tests. Antibiotic susceptibility testing was performed by the disk diffusion method (Kirby-Bauer). Multiple antibiotic resistance (MAR) index for each S. aureus was determined.

Results: Seventeen S. aureus isolates were identified. Nine S. aureus strains recovered from 18 samples from male patients was higher than 8 strains recovered from 25 samples from females. 21-30 age-group yielded the highest number of S. aureus isolates (7 strains), followed by 31-40 age group (5 strains). Eleven (64.7%) strains showed multiple resistances ranging from 55.6% to 88.8%, four (23.5%) strains showed multiple resistances ranging from 33.3% to 44.4%, one (5.9%) strain (N1) showed 100% resistance, while one (5.9%) strain (O1) showed 100% sensitivity. 70.6% of the isolates had a MAR index above 0.5 indicating that they probably originated from an environment where antibiotics are frequently used or abused. The highest resistance was offered to the β-lactam antibiotics, including oxacillin (88.2%), cloxacillin (82.4%) and amoxicillin/clavulanic acid (76.5%); and the cephalosporins: cefuroxime (70.6%) and ceftazidime (64.7). Resistance to ceftriaxone (cefuxitin) was the lowest (23.5%). Resistance to erythromycin was high (70.6%), but gentamicin and ofloxacin were offered relatively low resistance (41.2%) respectively.

Conclusion: The study revealed multiple antibiotic resistances in S. aureus isolated from hospitalized patients. The preponderance of multiple antibiotic S. aureus in the hospital environment continues to present challenges to the health sector. The high rates of resistance to the β-lactams – oxacillin, cloxacillin, amoxicillin-clavulanic acid and cephalosporins highlight the decreasing importance of β-lactams in the therapy of S. aureus infections.