Bacteriological profile of anaerobic infections and their antibiotic sensitivity pattern in a tertiary care hospital, South India

INTRODUCTION: Anaerobic bacteria are the predominant indigenous microflora of humans and play an important role in infections, some of which are serious and carry a high mortality rate. These organisms are recovered only infrequently from cultures of infected materials because of common short coming in collection and transport procedures. The technical difficulties, time consuming processes along with the prohibitive cost involved in the elaborate “setup” required for its isolation and identification usually put a limitation to the routine search for the anaerobes in most laboratories. In addition, their evolving resistance to most of the commonly used antimicrobial agents has made the choice of empiric based therapy impossible nowadays. There is a need for a standardised simple, cost effective and reliable system, we plan to evaluate the usefulness of the rapid identification of anaerobic bacteria isolated by VITEK-2 system and MALDI TOF. AIM OF THE STUDY: To determine the incidence of anaerobes among pyogenic infections. OBJECTIVES: 1. To isolate the anaerobes isolated from clinical specimen by conventional anerobic culture methods. 2. To identify the isolated organism using VITEK-2 ID & MALDI-TOF. 3. To determine the antibiotic susceptibility pattern of anaerobes isolated. 4. To determine the prevalence of metronidazole resistance among anaerobes. MATERIALS AND METHODS: A total of 150 clinical samples from patients with pyogenic infections were processed using the anoxamat anerobe culturing system .Isolated and conventionally identified anaerobes were compared with the automated VITEK-2 and MALDI TOF identification systems. All the isolated were subjected to antibiotic susceptibility testing. RESULT AND ANALYSIS: About 28 (18.66%) anaerobes were isolated from intra-abdominal infections, periodontal infections. cellulitis, necrotizing fasciitis etc. Pure isolation of anaerobes and anaerobes mixed aerobes with were seen in (57.1%) and (42.8%) respectively. Bacteroides fragilis (32%) was the predominant isolate followed by Prevotella disiens (14%), Clostridium clostridioforme (7%).E coli was the commonest aerobe followed by Klebsiella pneumoniae, Pseudomonas sp and others When the VITEK-2 and MALDI-TOF automated identification systems were compared for anaerobes, identification upto Genus level was comparable in 75% and most with B fragilis group and Prevotella sp . Poor comparability was observed with Clostridium species All the anaerobes were sensitive to Metronidazole and Imipenem and were resistant to Ampicillin and Clindamycin. CONCLUSION: Isolation and identification of anaerobic infections should be routinely performed and newer automated methods should be standardized and their databases updated because they are simple, cost effective and rapid. Regular monitoring of drug resistance to commonly used anaerobic antimicrobial should be done to identify the trends in resistance