Objective

To assess the trends in microbiological organisms identified from corneal scrapings from patients with infectious keratitis at a tertiary care medical centre in South India.

Methods

We reviewed the records of the microbiology laboratory at Aravind Eye Hospital in Madurai, India, from 2002 until 2012. We identified the microbiological causes of all corneal ulcers from the culture and smear results, and assessed for trends in bacterial and fungal keratitis over time.

Results

Of 23 897 corneal patients with ulcer with a corneal smear from 2002 to 2012 a fungal organism was identified in 34.3%, a bacterial organism in 24.7% and no organism in 38.3%. During this period, the annual number of keratitis cases due to bacteria decreased from 677 to 412, and the annual number due to fungus increased from 609 to 863. In analyses accounting for the total number of outpatients seen each year, the decline in number of smears positive for bacteria was statistically significant (p<0.001) but the increase in the number positive for fungus was not (p=0.73). The relative frequency of individual bacterial or fungal organisms remained relatively stable over this time.

Conclusions

At a tertiary eye care centre in South India, there has been a reduction in the numbers of smear-positive bacterial keratitis over the past 11 years. This decline likely reflects economic development in India and increased access to antibiotics.

Aims

To report trends in antibiotic resistance in cases of bacterial keratitis from a large eye hospital in South India.

Methods

In this retrospective cross-sectional study, the microbiology laboratory records of patients with infectious keratitis diagnosed at an eye hospital in South India from 2002 to 2013 were reviewed to determine the proportion with antibiotic non-susceptibility.

Results

3685 bacterial isolates had susceptibility testing performed over the 12-year period. The two most common organisms with resistance were Streptococcus pneumoniae (n=1204) and Pseudomonas aeruginosa (n=894). Antibiotic non-susceptibility was generally uncommon for these two organisms and no significant trends were detected over the course of the study. In contrast, Staphylococcus aureus (N=211) isolates demonstrated a significant increase in fluoroquinolone non-susceptibility over the 12-year study period. This coincided with a significant increase in methicillin-resistant S. aureus (MRSA) during the study period, though the increase in fluoroquinolone resistance was likewise seen in methicillin-sensitive S. aureus (MSSA). For example, ofloxacin resistance in MSSA increased from 11.1% in 2002 to 66.7% in 2013 (p=0.002). No trends were apparent for the aminoglycosides, cefazolin or vancomycin, for which in vitro non-susceptibility generally appeared to be low.

Conclusion

Resistance to antibiotics was generally stable for infectious keratitis isolates from a large eye hospital in South India, except for S. aureus, which experienced a significant increase in fluoroquinolone resistance from 2002 to 2013. Fluoroquinolone antibiotics currently have poor in vitro activity against both MRSA and MSSA in South India and are therefore not the ideal therapy for Staphylococcal corneal ulcers.