Isolation and antimicrobial susceptibility pattern of Nocardia among people with culture-proven ocular infections attending a tertiary care eye hospital in Tamilnadu, South India

Abstract

Aims: To evaluate the epidemiology, microbiological features, as well as antibiotic susceptibility patterns of Nocardiafrom cases with ocular nocardial infections seen over a period of 8 years in a tertiary eye care hospital. Methods: Microbiology records of 164 cases of culture-proven ocular nocardial infection diagnosed between March 1997 and February 2005 were reviewed retrospectively. The outcome data included isolation rate, predisposing factors, demography (age and sex), and category of infection, utility of conventional diagnostic methods, microbiological profile, and antibiogram-resistogram patterns. Results: A total of 164 (3.1%) Nocardia species were identified among 5378 culture-proven cases. Ninety-six (58.5%) isolates were from corneal scrapings followed by vitreous biopsy (17.0%). Most (58.0%) of the cases were between 51 and 80 age groups. Male preponderance was obvious. All the 164 (100%) nocardial infections were identified by culture. Of 125 ocular specimens subjected to Gram's staining, nocaridal filaments were identified in 70 (56%) specimens. In addition to KOH mounting, modified AFB staining was also found to be helpful. Upon in vitro susceptibility testing, 98.7 and 90.2% of nocardial isolates showed sensitivity towards amikacin and ciprofloxacin, respectively. Conclusions: Ocular nocardiosis is relatively rare among ocular infections. Amikacin and ciprofloxacin are highly effective in treating ocular nocardiasis. Prompt and accurate microbiological diagnosis and early administration of these antibiotics may have a positive effect on the ocular outcome as well as in controlling nocardial prevalence.