Bacteriology of Compound (Open) Fracture Wounds at ‘Tikuranbessa’ Specialized Hospital, Addis Ababa University, Ethiopia

Background: Infection of open fractures depends on the microbial environment, fracture handling, and host factors. Sound knowledge of the bacteriological epidemiology and antimicrobial susceptibility helps to rationally select prophylactic antibiotics.
Objectives: To isolate and identify the bacterial agents present on compound (open) fracture wound and to determine the antimicrobial susceptibility pattern.
Setting: Addis Ababa University, ‘Tikur Anbessa Specialized Hospital.
Methods: Between November 2007 and May 2008, a cross-sectional prospective study was conducted to determine the bacteriology of open fracture wounds of 191 informed and consented patients (200 wounds) who visited the orthopedic department of ‘Tikur Anbessa’ Hospital. Wounds were graded using Gustilo-Anderson’s classification. The detailed bacteriological profile of the wound swabs collected by Levine’s technique is documented. All of the wound specimens were processed for microscopic examination, culture, and sensitivity testing.
Results: Of the 191 patients, 82.7% were male whose average age was 31.55 years (age range 4 to 75 years). Most of the open fractures were caused by road traffic injuries (37.2%) and occurred in the lower extremity bones (60.0%). Twenty-three percent of the open fractures were Gustilo-Anderson grade I, 41.5% grade II, 14.0% grade IIIA, 5.5% grade IIIB, and 16.0% grade IIIC. A total of 162 bacterial pathogens were isolated from the open fracture wounds sampled. Staphylococcus aureus was the dominant isolate (14.8%), followed by Acinetobacter spp. (11.4%). The gram-positive and gram-negative bacteria accounted for 34.0% and 66.0%, respectively. Eighty-two (41%) of the wounds were culture-positive, of which 51.2% showed mono-microbial growth while 48.8% showed polymicrobial growth. All Clostridium spp. were susceptible to tetracycline, doxycycline, and kanamycin and showed low level of resistance (<60%) against chloramphenicol, clindamycin and penicillin. All gram-negative bacterial isolates showed low level of resistance (<60%) to all antibiotics tested except for ampicillin and amoxicillin for which they showed (60-80%) intermediate level resistance. Fifty-one percent of the gram-negative bacterial isolates were identified as multiple drug resistant.
Conclusion: Staphylococcus aureus was the commonest isolate followed by Acinetobacter species, E. coli and Pseudomonas species. Gentamicin, ciprofloxacin, and norfloxacin were the most effective drugs against the tested gram positive and gramnegative bacteria. The findings underscore the need for routine microbiological investigation of open fracture wounds and monitoring antimicrobial resistance pattern for the use of prophylactic and therapeutic antibiotics.