Prevalence, Risk Factors, and Microbiological Profile of Early Surgical Site Infection Following Orthopaedic Implant Surgery at Kenyatta National Hospital

Abstract

Background: The prevalence of surgical site infections (SSI) in orthopaedic surgery has been on the rise especially in low and middle-income countries (LMIC). This has been attributed to the increased number of trauma patients due to the increased incidence of motor vehicle and motor cycle crashes. Kenya has witnessed a similar increase, more so from motor cycle related crashes, leading to an increase in the number of fractures treated operatively. Time to ORIF, duration of surgery, antibiotic prophylaxis are some of the risk factors for SSI, however, data on prevalence and risk factors of SSI within our population to inform preventive strategies remain scarce. Study objective: To determine the prevalence, risk factors and causative bacterial pathogens using microscopy culture and antibiotic sensitivity patterns of SSI following surgery for long bone fractures at level 6 referral hospital Kenyatta(KNH). Study design: Prospective observational analytic . Study setting: The study was carried out in orthopaedic clinic (OC) and wards (OW) at the Kenyatta National Hospital (KNH) between 11th February 2022 and 2nd May 2022 Patients and methods: The collected data were transferred from password-coded data digital collection sheets into analysis software for data cleaning and coding prior to analysis. Data was stored in password-protected computer folders to maintain anonymity of the study subjects. Data analysis was carried out using the Prism 7 (GraphPad Software, San Diego, CA, USA) and SPSS (IBM Statistics Software Version 25, Armonk, New York, USA). Categorial data was reported as frequencies (%). Continuous data were subjected to normality tests (histogram and Q-Q plots with Kolmogorov-Smirnov test) and reported as mean and standard deviation (SD). Comparison of patient and fracture characteristics between patients with and without SSI was carried out using the Independent Student’s-t test (continuous variables) and Chi-square xii statistic (categorical variables). Multivariate logistic regression analysis was performed to identify risk factors for SSI, adjusting for the age,BMI ,sex and comorbidities, and to calculate adjusted odds ratios (ORs) with the corresponding 95% Wald CI. Throughout the analysis, a p<0.05 was considered statistically significant at a 95% confidence interval. Results: A total of 130 patients were recruited into this study. They were generally young (mean age: 33±12.8 years) with a male predominance (83%). The mean body mass index (BMI) was 23.7±2.1 Kg/M2, with 13 (10%) having diabetes mellitus (DM). The most fractured bone was femur (n=66 patients, 50.8%). The mean injury severity score (ISS), pre-operative hospital stay and ASA (American Society of Anaesthesiology) score were 21.6±11.2, 12±9.2 days 1.0±0.1 and respectively. A total of 18 patients (13.8%) developed surgical site infection (SSI). Compared to those without SSI, patients with SSI were predominantly male (p=0.007), had higher BMI (p=0.003) and diabetes mellitus (DM) (p=0.007), had higher incidence of open fractures (p=0.046), higher ISS (p=0.008), and were more likely to require pre-operative blood transfusion (p<0.001) and ICU admission (p<0.001). In the multivariate adjusted logistic regression model, female sex (OR= 5.52, 95% CI 1.15-26.65, p=0.033), presence of diabetes (OR= 9.72, 95% CI 1.83-51.76, p=0.008), higher BMI (OR= 1.31, 95% CI 1.02-1.69, p=0.033), need for pre-operative blood transfusion (OR= 68.21, 95% CI 5.42-858.32, p<0.001) and need for ICU admission (OR= 8.10, 95% CI 5.18-12.65, p<0.001) were significant predictors of development of SSI. The commonest organism isolated was staphylococcus aureus (SA) (70%). Conclusion: The burden of surgical site infections (SSI) following orthopaedic surgery remains high. Diabetes mellitus (DM), higher body mass index (BMI), pre-operative blood transfusion and intensive care unit admission were associated as risk factors for SSI in this study cohort. Commonest isolated organism was Staphylococcus aureus (n= 7patients,70%). Culture isolates display a concerning trend of increased resistance to commonly prescribed antibiotics. Recommendation: 1.Increased SSI surveillance mearures in Orthopaedic patients with diabetes and obesity comorbidities 2. Routine establishment of sensitivity patterns of SSI isolates to guide antimicrobial selection is recommended.