Vancomycin Susceptibility Patterns of Methicillin Resistant Staphylococcus Aureus Isolates From Wounds at Madina Hospital in Mogadishu, Somalia

Abstract

Background: Methicillin Resistant Staphylococcus aureus (MRSA) is considered the main cause of all community acquired infections as well as nosocomial to susceptible individuals. Methicillin Resistant Staphylococcus aureus infections account for 64% of general health care setting infections and 40 % of almost all infections in the Intensive Care Unit. However, there have been records of incidences of increased prevalence of MRSA resistance to some of the glycopeptides antibiotics used in the treatment of wounds such as vancomycin. Objective: To demonstrate the prevalence and vancomycin susceptibility pattern of MRSA isolates from patients having open wounds at Madina Hospital. Methodology: Study design and site: This was a cross-sectional descriptive study recruiting 151 adult patients. The study was conducted in surgical wards, dressing room and burn unit. Study participants: Adult patients with wounds seeking treatment at Madina Hospital during the study period. Laboratory procedure: Specimens were collected from the open wound and inoculated into Mannitol salt agar. Those with yellow colonies were aseptically transferred into Medysinal BD Chromoagar. Bacterial suspension prepared and inoculated aseptically on Mueller Hinton Agar plates. Vancomycin antibiotic discs 30 μg was then introduced. Staphylococcus aureus were categorized according to MIC of vancomycin; if it is ≤ 4 μg/mL, it is a VSSA. It is VISA if vancomycin drug MIC is 4-8 μg/ml and it is considered as VRSA if the minimum inhibitory concentration is ≥16 μg/ml. Results: The number of the patients recruited were151. The patients were recruited from three different wards, namely the surgery ward (n=109; 72.3%), the dressing room (n=22; 14.6%) and the burn unit (n=20; 13.3%). Patients with bullet wounds were the most frequent at the hospital representing a quarter of the patients (n=38; 25.2%) in the study, followed by explosive wounds (n=22; 14.6%) and the least frequent were chemical wounds (n=3; 2.0%). Approximately half of the patients stayed in the hospital for more than 2 weeks (n=74; 49.0%). Most of the patients had no other underlying disease (n=122; 80.8%). There was a significant number of patients with diabetes (n=14; 9.3%). Majority of the patients were put on an antibiotic drug combination therapy. The prevalence of MRSA in this population was estimated at 17.9% (n=27). All MRSA isolates were susceptible to Vancomycin. Conclusion: The prevalence of MRSA among the patients having wounds in this study was high. All MRSA isolates were susceptible to Vancomycin. The findings of our study indicate that the three wards in which the patient was recruited, the surgical ward appeared the highest infection rate of MRSA (13.2%) followed by the burn unit (4.6%). The risk factors for MRSA that were evaluated include; hospital stay, antibiotics used for the treatment of the wound and prosthetic device. Only duration of hospital stay was found to be significantly associated with the presence of MRSA infection (p<0.001).

Recommendations: Incidence of MRSA infections could be reduced by implementing continuous surveillance of nosocomial infections, to know MRSA prevalence and antimicrobial susceptibility profile which is essential in a selection of suitable empirical treatment, MRSA screening program for patient particularly high-risk individuals and healthcare workers for infection control measures. Long stay in hospital should be minimized to reduce the risk of nosocomial infections as well as health cost. Keywords: Methicillin resistant Staphylococcus aureus, Madina Hospital, Intensive Care Unit, Chromogenic agar, Clinical Laboratory Standard Institute, MIC.