Study of microbilogical flora and role of primary bacterial cultures in management of open fractures of long bones

Author(s): Dr. Shiraz Bhatty, Dr. Rajesh Paul and Dr. Harjit Kaur

Abstract: Background: Microbiology of open fracture wounds is constantly changing. A clear understanding of the bacterial flora that could be expected is needed in order to administer a rational and effective antibiotic treatment for open fractures. The role and efficacy of primary bacterial cultures in management of open fractures is also debatable and needs further evaluation.
Methods: One hundred patients with one hundred and seven open fractures of long bones were studied prospectively, from March 1^st 2001 till February 28^th 2002. Wound swabs were obtained at pre-debridement, intra-operative, post debridement, 1^st dressing/after 24hrs intervals, subsequently every week and sent for cultures. The infecting organism, its antibiotic susceptibility and its correlation between cultures at different stages was noted.
Results: An infection rate of 43.9% was noted. Most of the initial wound cultures, showed growth of Gram-negative organisms (76%), commonest being Pseudomonas (36%) and Acinitobacter(20.7%). However, majority of infections after 2^nd week were caused by Gram-positive organisms. Staphylococcus aureus (93.5%) was the predominant Gram-positive organism.
None of the organisms grown on admission and pre-debridemet cultures eventually caused infection; however, 28% of cases with negative cultures eventually got infected. Post debridement cultures were positive in none. Among the cultures obtained at 1^st dressing 40% of organisms grown eventually caused infection whereas 60% showed growth with different organism.
Conclusions: A shift in the bacterial flora occurs in compound fracture wounds from Gram-negative to Gram-positive organisms after the 2^nd week. Cultures obtained at admission, predebridment, posted brid ment and at 1^st dressing or after 24hrs are not reliable indicators of subsequent wound infection.

DOI: https://doi.org/10.22271/ortho.2018.v4.i2b.14