Antibacterial susceptibility patterns and risk factors for surgical site infections at Moi Teaching and Referral Hospital, Eldoret-Kenya

Abstract

Background: Surgical Site Infection (SSI) poses a burden to patients and the healthcare system by increasing cost, hospital stay as well morbidity and mortality. The incidence of SSI in sub-Sahara Africa is around 10% for clean wounds and up to 60% for dirty wounds. The etiology, risk factors and antibacterial susceptibility among patients with SSI is largely unknown at the Moi Teaching and Referral Hospital (MTRH). Objective: To determine the risk factors, bacterial etiology and antibacterial susceptibility of surgical site infections at Moi Teaching and Referral Hospital, Eldoret-Kenya. Methods: This was a case control study involving 57 cases of SSI and 114 matched controls. Questionnaires were administered to all study patients to collect data on sociodemographic characteristics, wound class and potential risk factors for SSI. Pus swab was collected from the cases and inoculated in culture media after which antibacterial susceptibility test was done on isolated organisms using modified Kirby-Bauer disc diffusion in Mueller Hilton agar. Blood cultures were done for patients who presented with systemic features of infection including fever of 37.50C and above. Frequencies and proportions were determined for risk factors, etiology and antibacterial susceptibility. Predisposing factors were compared between cases and controls using the chi-square test to determine “p” values and Odds ratios. A “p” value of less than 0.05 was considered significant. Results: Risk factors for SSI were smoking (p<0.001, OR=5.8), diabetes mellitus (p=0.025, OR=3.5) and long operation time (p<0.001, OR=1.5). A total of 55 bacterial organisms were isolated from 46 patients. Out of these 5 were from 12 blood cultures done. The most common isolate was Staphylococcus aureus, 22 (40.0%) followed by Escherichia coli, 11 (20.0%), Acinetobacter baumannii- 6 (10.9%), Klebsiella pneumoniae -5 (9.1%), Pseudomonas aeruginosa-4(7.3%), Proteus mirabilis -2(3.6%) and Streptococcus pyogenes – 1 (1.8%). Methicillin Resistant Staphylococcus Aureus (MRSA) comprised 59% (13) of all Staphylococcus aureus. Gram positive bacteria had over 50% resistance to ceftriaxone, cotrimoxazole, ciprofloxacin, azithromycin, erythromycin, cefuroxime and levofloxacin. Gram negative bacteria had more than 50% resistance to ceftriaxone, cefotaxime, ceftazidime, cefepime and levofloxacin. MRSA and Acinetobacter baumannii showed multidrug resistance. Conclusion: Smoking, diabetes mellitus and prolonged operation time are risk factors for SSI. Staphylococcus aureus was the commonest causative agent for SSI with MRSA constituting 59% of Staph aureus infection. Organisms causing SSI were resistant to most commonly used antibacterial agents at MTRH. Recommendations: Active surveillance for SSI causing organisms and their susceptibility patterns should be instituted at MTRH. Antibacterial use should be rationalized according to local susceptibility patterns. Patients with diabetes mellitus, history of cigarette smoking and prolonged operation time should be closely monitored for SSI.