Clinically Significant Diphtheroids - An emerging pathogen,their speciation and antimicrobial susceptibility patterns in a tertiary care hospital

Background- Non-diphtherial Corynebacteria, also referred to as Diphtheroids, are a diverse collection of bacteria which are non sporing gram positive bacilli belonging to the genus Corynebacteria. Till recently, the pathogenic potential of coryneform bacteria has been underestimated. Although frequently considered as contaminants, these organisms have been associated with various clinical infections in the recent times.Aim-To isolate,identify and speciate the clinically significant diphtheroids obtained from various samples and study their antimicrobial susceptibility patterns. Materials and Methods A total of fifty isolates of clinically significant diphtheroids from various clinical samples collected over a period of 6 months were selected for this study. Speciation was done using a panel of tests and antimicrobial susceptibility was tested by using a combination of Clinical and Laboratory Standards Institute (CLSI) and the British Society for Antimicrobial Chemotherapy( BSAC) guidelines due to absence of definitive CLSI guidelines. Results Over a period of 6 months ,50 isolates of clinically significant diphtheroids were obtained from various clinical samples.Diabetes mellitus was the most common co-morbid condition seen in 42 percentage of the patients.Corynebacterium amycolatum was the predominant species( 66 percentage) in this study followed by Corynebacterium glucoronolyticum (10 percentage) and Corynebacterium minutissimum (10 percentage).The remaining species comprised less than 25 percentage of the isolates. In this study 88 percentage of the isolates were sensitive to each penicillin and erythromycin and 92 percentage were sensitive to each gentamicin and cotrimoxazole. All the strains were found to be susceptible to ciprofloxacin,tetracycline and vancomycin. Conclusion This study was done in an attempt to ascertain the clinical significance of diphtheroids among various infections and to study the susceptibility patterns of this group of organisms to some common antibacterial agents.