Coryneforms the Opportunistic Pathogens - An Emerging Challenge for Immunocompetent Individuals (original) (raw)

Coryneforms have emerged as important pathogens causing severe human infections in immunosuppressed patients. However, it is increasingly being perceived that the pathogenic potential of Coryneform bacteria is being underestimated and it is not limited to merely this group of patients. These organisms are reported to cause serious infections such as bacteremia, valvular endocarditis, neurosurgical shunt infections, meningitis, brain abscess, peritonitis, osteomyelitis, septic arthritis, pneumonia, empyema and urinary tract infections. The study was conducted in the Department of Microbiology, Jawaharlal Nehru Medical College and Hospital, Aligarh, INDIA for a period of eight months from August 2007 to March 2008. All the patients in the study were divided into two groups: (i) Immunocompromised (ii) Immunocompetent. Direct microscopic examination was done by Gram staining, followed by culture. All the isolated Coryneform species were subjected to antimicrobial susceptibility testing using Kirby bauer disc diffusion method on Mueller Hinton agar incorporated with 5% sheep blood. A total of 2508 samples (68.6%) showed growth on culture. Coryneforms were isolated and considered as pathogens in 5.5% samples. Monomicrobial infection of Corynebcaterium species was more common (69.1%) with surgical site infection (27.3%) as the commonest presentation. Coryneforms isolates from the immunocompetent patients accounted for 98(70.5%) isolates, whereas 41(29.5%) isolates were from patients with an immunocompromised status. C. minutissimum was the commonest Coryneform isolated in both the groups. The other Coryneform species isolated were C. jeikium, Microbacterium species, C. xerosis, C. striatum, C. urealyticum, C. afermentans, C. amycolatum and C. ulcerans. Alarmingly widespread antibiotic resistance was observed among most of the Coryneforms. The average sensitivity of the-lactam antimicrobials being just 55% and the aminoglycosides even less than 50% (48%). Only 67(47.5%) strains were sensitive to flouroquinolones. Linezolid was the only antimicrobial to which all the Coryneform isolates included in this study were uniformly sensitive. This study highlights the need for maintaining a high degree of suspicion as far as Coryneform infections are concerned. They should not be dismissed as skin commensals in immunocompetent patients without determining their clinical relevance. Sensitizing clinicians about these emerging pathogens and their multidrug resistant nature is also essential.