Study of Organisms Causing Osteomyelitis in a Tertiary Care Hospital

Abstract

BACKGROUND The term osteomyelitis (OSM) was first used by the French surgeon Edouard Chassaignac in 1852, who defined the disease as an inflammatory process accompanied by bone destruction caused by an infecting microorganism. The clinical manifestation and the natural history of OSM depend on several factors. OSM mostly affects the growing ends of long bones. We wanted to study the organisms causing osteomyelitis and their antimicrobial susceptibility pattern. METHODS Pus and bone aspirate were collected from 115 diagnosed patients of osteomyelitis and were processed for isolation of organisms by standard microbiological techniques. Isolates were identified by various biochemical reactions and were subjected to antimicrobial susceptibility test as per CLSI guidelines by Kirby-Bauer disk diffusion technique on Mueller Hinton agar (MHA). Data collected in the questionnaire was entered and analysed in Epi Info software version 7.2. RESULTS In 101 samples, 116 organisms were isolated. In 14 samples no organism was isolated, which can be attributed to the viral aetiology, parasites and anaerobes. Acute Osteomyelitis (AOSM) was found to be more common in the age group of 1-10 years, whereas chronic osteomyelitis (COSM) was found more commonly in 21-30 and 31-40 years age group. Male to Female ratio was 2.2:1. Bones involved in AOSM and COSM were mostly femur followed by tibia and humerus. S. aureus was the most predominant isolate. All the isolates of S. aureus showed 100% sensitivity to Vancomycin, Amikacin, Netilmicin, Chloramphenicol. Out of 48 isolates of S. aureus, 37.50% were MRSA, 6.25% were ICR, 14.58% were MRSA+ICR found. CONCLUSIONS Osteomyelitis is found to be highest in third decade, with the males being predominantly affected. Acute osteomyelitis is predominantly seen in children, whereas chronic osteomyelitis in adults. Even though Staphylococcus aureus has always remained the most common etiological agent of osteomyelitis, increasing infections due to Gram negative bacilli and even poly-microbial infections are gaining importance. MRSA infection is known to increase post-operative complications. Introduction of MBL or carbapenemase production in Gram negative bacilli is a matter of great concern. Timely knowledge of aetiology and antimicrobial resistance pattern of osteomyelitis isolates can help in rational use of antibiotics and control of drug resistance.