Purpose: To analyze the microbiological profile and in vitro antibiotic susceptibility patterns of bacterial isolates in canaliculitis, an infection of the lacrimal drainage system of the eye.

Methods: The laboratory records of patients presenting with canaliculitis from whom specimens were obtained for microbiological investigations at our tertiary eye care centre in South India from January 2010 to December 2020, were reviewed.

Results: A total of 130 canalicular pus samples were collected from 112 patients and submitted for microbiological studies during the study period. A total of 183 micro-organisms were isolated from 115 culture-positive specimens. The micro-organisms isolated were predominantly aerobic Gram-positive bacteria (83.44%), with Coagulase-negative Staphylococci (CoNS/Other Staphylococcus spp) (31.69%), Corynebacterium spp (15.3%), Staphylococcus aureus (9.84%) and Viridans Streptococci (9.84%) accounting for a majority of the isolates. Actinomycesspp (6.56%) was the most common anaerobic bacterium isolated. Our study revealed several bacteria not previously associated with canaliculitis namely Ottowia spp, Elizabethkingiameningoseptica, Aeromonassalmonicida, Capnocytophagaochracea and Campylobacter gracilis. Polymicrobial aetiology was observed in 39.13% of culture-positive samples. Analysis of antibiotic susceptibility patterns of the isolates revealed a high proportion of Gram-positive bacteria susceptible to chloramphenicol (90.16%) compared to fluoroquinolones including ciprofloxacin (74.42%), norfloxacin (64.15%) and gatifloxacin (60.49%).

Conclusion: This study represents the largest series of canaliculitis reporting the microbiological profile and antibiotic susceptibilities of the isolated micro-organisms, till date. Gram-positive bacteria accounted for a majority of isolates, predominated by Staphylococcus spp. The increasing resistance of Gram-positive bacteria to fluoroquinolones warrants antibiotic treatment in canaliculitis is based on in vitro antimicrobial susceptibility patterns.