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Year : 2017   |  Volume : 5  |  Issue : 4  |  Page : 195-203

A study on bacterial and fungal isolates and their antimicrobial susceptibility pattern in patients with chronic osteomyelitis in a tertiary care hospital
Chronic osteomyelitis is a major challenging problem in our country, and it is a persistent disease difficult to treat and eradicate completely. The aim of the study is to analyze the predisposing factors associated with chronic osteomyelitis and to study the causative organisms and their antimicrobial susceptibility pattern and check the resistance pattern in common isolates. It is a cross-sectional study done during a time between October 2011 and September 2012 and was included in the analysis of the data. Total of 120 patients were included prospectively. In 120 patients detailed history were recorded. Collection of samples was done under strict aseptic precautions. Pus, swabs from sinus tract and sequestrum were the samples collected. Processing of samples was done by culture both bacterial and fungal, catalase test, oxidase test, biochemical reactions, and antimicrobial susceptibility was done by kir by-Bauer disc diffusion method according to CLSI guidelines. All the tests were done as per protocol. ATCC strains Staphylococcus aureus - ATCC 25923, Escherichia coli - ATCC 25922, and Pseudomonas aeruginosa - ATCC 27853 were used as controls. Detection of β-lactamase enzymes in Gram-negative bacilli (GNB), detection of methicillin resistance in S. aureus were also done phenotypically. Minimum inhibitory concentration (MIC) of vancomycin was done to detect vancomycin resistance against S. aureus. Fungal cultures were identified by macroscopic appearance, microscopy analysis (Gram staining, LCB), germ tube test, CHROM agar media, and sugar fermentation. MIC determination by microbroth dilution method was also done. ATCC Candida albicans 90028 was used as quality control. In this study, 97 (80.83%) were males and 23 (19%) were females. 40% of the patients had a duration of the illness from 7 to 12 months. 35.8% of patients had illness ranged from 13 to 24 months. 50.8% of patients had compound fracture leading to infection. Among the samples collected, 63 (52.5%) were sequestrum/per-operative collections of pus and tissue fluids, and 57% (47.5%) were swabs. Culture positivity was 83.3%, an increased number of polymicrobial (12.2%) infections were noted in swabs, though monomicrobial infection was the most common type even in swabs (57.8%). The common organism isolated was S. aureus (36.7%), S. aureus which was the most common bacteria isolated in this study showed 100% sensitivity to Rifampin, 97.4% sensitivity to vancomycin, 64% sensitivity to amikacin, chloramphenicol and Erythromycin, 51.2% to Penicillin, and 51.2% were sensitive to cefoxitin. Among Gram-negative isolates, P. aeruginosa was the most common isolate, which showed 100% sensitivity to imipenem, 76.4% to cefoperazone sulbactam, 52.9% to amikacin, and 35.2% to cefotaxime and ceftazidime. One isolate of Mycobacterium tuberculosis was sensitive to all first and second line drugs. The one fungal isolate Candida tropicalis was sensitive to fluconazole, amphotericin B, itraconazole, and voriconazole. 40.5% of aerobic bacteria were multidrug-resistant. 56.6% were aerobic Gram-positive cocci (GPC) and 43.3% were aerobic GNB, one acid-fast bacillus M. tuberculosis, and one yeast C. tropicalis were isolated in the study. Among GPC, S. aureus (36.7%) was the most common pathogen isolated followed closely by Staphylococcus epidermidis (10.5%). All GPC except one were sensitive to vancomycin and rifampin. Among GNB, all were sensitive to imipenem and 90% to cefoperazone sulbactam. Pseudomonas had lower sensitivity (76.4%) to cefoperazone. Various factors in open fracture leading to chronic osteomyelitis each patient has to be routinely monitored after trauma and treatment for developing osteomyelitis. Treatment given in the early stage will prevent dreadful complications and sequelae.
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