Nocardia asteroides ocular infection

Background

Nocardia asteroides can cause ocular infection in immunocompetent and immunocompromised individuals following minor trauma. Hence present study was carried out to isolate N. asteroides from the patients attending a tertiary eye care hospital and to analyse the antibiotic susceptibility pattern of the Nocardia isolates.

Methods

The ocular samples viz., corneal swab, corneal scraping, aqueous tap and vitreous tap were processed for culture and the isolated Nocardia species were further confirmed for speciation by standard microbiological procedures. Antibiotic susceptibility analysis for the confirmed isolates of N. asteroides was performed by agar disk diffusion method following the guidelines of Clinical Laboratory Standard Institute (CLSI, 2000).

Results

Out of 280 ocular clinical specimens collected, 25 isolates of N. asteroides were obtained. The rest of the pathogens included bacteria, fungi and mixed culture. The age in most of the cases yielding Nocardia was below 5 years (12%) and above 60 years (52%) and men (76%) were more infected than women (24%). Precisely, 17 isolates of N. asteroides were isolated from corneal ulcer, 5 from corneal swab and 3 from endophthalmitis. Upon analysis of antibiotic susceptibility tests the nocardial isolates were found to be more susceptible to fourth generation fluoroquinolones antibiotic family (75%), amikacin (66%), ampicillin (80%), vancomycin (50%) and norfloxacin (75%).

Conclusion

Ocular nocardiosis remains difficult to recognize, there by leading to misdiagnosis and underestimation of its incidence.