Clinical and microbiological profile of post-traumatic osteomyelitis in Yaoundé Central Hospital

Chirurgie et spécialités, Université de Yaoundé I
June, 2017


Introduction: Osteomyelitis is an infection of bony tissue. It could arise by three routes: haematogenous, local spread from surrounding infected soft tissues, or direct inoculation of germs following trauma (open fractures or bone surgery). The incidence of post-traumatic osteomyelitis has been rising in our setting because of the increase in frequency of road traffic accidents and orthopaedic procedures. However, osteomyelitis is a serious and invalidating illness characterised by a high rate of treatment failures and often requires long periods of treatment and hospitalisation leading to temporary impairment and at times long lasting disability or even permanent handicaps. Its treatment comprises of surgical debridement of all necrotic bone and soft tissue along with use of appropriate antimicrobial therapy. Treatment is becoming increasingly troublesome due to rise in drug resistant isolates in osteomyelitis cases. A good knowledge of the bacterial profile and their sensitivity pattern is therefore essential to initiate a good antibiotherapy while awaiting culture results.
Objectives: To determine the bacteriological profile and antimicrobial susceptibility pattern of post-traumatic osteomyelitis in Yaoundé Central Hospital (YCH).
Materials and Methods: We carried out a descriptive cross-sectional study from 15th November 2016 to 15th May 2017. Cases of post-traumatic osteomyelitis were recruited at the Orthopaedic ward of YCH and after obtaining patient’s consent, socioclinical informations were taken and clinical specimens like pus, pus swaps, bone marrow contents and bone sequestrum were collected and sent to the Bacteriology Laboratory of Yaoundé University Teaching Hospital (YUTH) for analysis. The samples were cultured aerobically in routine culture media. The organisms isolated were identified by routine standard operative procedures. Antimicrobial susceptibility testing was done by Kirby-Bauer’s disc diffusion method and the results interpreted using the CASFM guidelines. Data obtained was entered in CSPro Version 6.3.2 software and transferred into the software SPSS Version 20 for analysis. Results were presented in counts and percentages and comparisons made using Fischer’s Exact test as applicable.
Results: Thirty patients with post-traumatic osteomyelitis were admitted in the orthopaedic ward within our study period and were included in our study. We noted a predominance of the male sex with a sex ratio of 1.8:1. Majority of the patients were in the age group of 21-50 years (67.8%). Surgical exposure was the cause of bone exposure in 23% of the patients against 76% of patients who had an initial open fracture. 58% of the infections occurred on prosthetic devices. The commonest bone affected was the tibia (48.5%) followed by the femur (32.3%). The 31 samples yield 29 (93.5%) positive culture results; 52% being monobacterial giving a total of 48 bacterial isolates (average of 1.4 bacteria per sample). We did not isolate any fungi. Enterobacteria represented 62.5% of the isolates followed by non-fermenting Gram negative bacilli (18.8%) and Gram positive cocci (18.8%). The most predominant species was Escherichia coli with a prevalence of 29%, followed by Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella pneumoniae (all 22.6%). All the Staphylococcus aureus strains were sensitive to Imipenem, Rifampicin, Flucidine, Lincomycin, and to Vancomycin whereas the Gram negative bacilli were mostly sensitive to Imipenem (89-96.7%), Amikacin (75-82.1%) and to a lesser extend Quinolones (54%- 66.7%) and Piperacillin/Tazobactam (48-55.6%) and Ceftazidime (42.5-44%).
Conclusion: Nosocomial bacteria dominate the bacterial flora of posttraumatic osteomyelitis in our setting and these bacteria are developing resistances to most of the routinely used antibiotics. Appropriate implementation of hygienic practices and appropriate selection of antibiotics based on cultures results will help treat the disease successfully in the early stages and prevent the spread of multidrug-resistant strains to limit morbidity.