Bacteriological spectrum of post operative wound infections and their antibiogram in a tertiary hospital, Dar es salaam, Tanzania

Abstract

Background: Surgical site infection (SSI) is among the most common problem for patients who undergo operative procedures. It remains a common and widespread problem contributing to morbidity and mortality; partly attributed to increase in infections due to antimicrobial resistant bacterial pathogens. In Tanzania there has been limited data regarding the magnitude of SSIs due to antimicrobial resistant pathogens as well as the resistant pattern to antibiotics commonly used in the treatment of these infections. Objective: To determine the spectrum of bacteria isolates from postoperative wound infections and their antimicrobial susceptibility patterns at Muhimbili National Hospital (MNH) and Muhimbili Orthopedic Institute (MOI). Methodology: This was a descriptive cross sectional study which was conducted among patients with post operative wound infections in the general surgery and obstetrics/gynecology wards at MNH and Orthopedics and Trauma unit at MOI. The study participants were consecutively recruited in general surgery, obstetrics/gynecology wards at MNH and orthopedics and trauma wards at MOI from September 2011 to February, 2012. Structured questionnaires were used to collect social demographic characteristics, clinical history and operative information from patients and their case notes. Culturing for colony characteristics followed by Gram stain was used for provisional identity of pathogenic bacteria. Further identification was done by a set of biochemical tests, API 20E, and VITEK. Antimicrobial susceptibility pattern of isolated bacterial pathogens was determined by Kirby Bauer disc diffusion method. Results: Pseudomonas aeruginosa was the most frequently isolated pathogenic organism from post operative wound infections. Most of the Gram negative bacteria isolated were multiply resistant to antimicrobial agents tested; but all were sensitive to carbapenems. Eighty eight percent (88%) of enteric gram negative rods were multi-drug resistance. ESBLs production viii was detected in 92.3% of Escherichia coli and 69% of Klebsiella pneumoniae. Forty four percent (44%) of the 18 S. aureus isolates obtained were MRSA. Conclusion and recommendation: Pseudomonas aeruginosa was the most common isolate from SSI. Most of gram negative isolates were multiply resistant to commonly prescribed antimicrobial agents. Also there was an increase in ESBLs producing Enterobacteriaceae as well as MRSA strains. Routine culture should be performed whenever SSI is suspected and choice of antibiotics for treatment of SSIs should be guided by routine antimicrobial sensitivity (including MRSA and ESBL screening) testing. Ciprofloxacin should replace first line antibiotics for empirical treatment of SSIs; and strict guidelines for antibiotics prescriptions in treatment of SSIs should be established.