Purpose: To report demographics, organism occurrence, and in vitro resistance trends for patients presenting with bacterial conjunctivitis at Bascom Palmer Eye Institute in Miami, Florida from 1994 to 2003.
Design: Retrospective cross-sectional study.
Participants: Two thousand four hundred eight eyes.
Methods: The microbiology records of all patients with bacterial conjunctivitis seeking treatment at Bascom Palmer Eye Institute from January 1, 1994 through December 31, 2003 were reviewed. Data on age, gender, culture-positive trends, and in vitro susceptibility were collected. In vitro susceptibility data were generated using disc diffusion and minimal inhibitory concentrations.
Main outcome measures: Positive cultures by age, gender, and organism and in vitro resistance.
Results: During the 10-year period, 1254 culture-positive pathogens were recovered from 2408 consecutive conjunctival swabs (52.1%). The culture-positive rate from 1994 to 1998 was 55% and declined to 44% in the second 5 years. Male and female patients contributed equal percentages to the total isolates (50.0%). Females had a higher percentage of gram-positives than males (55.5%; P = 0.033). Gram-positive pathogens accounted for 52.2% of culture positive isolates. Staphylococcus aureus was the most frequent isolate overall (37.6%) and in patients older than 6 years (47.8%). Methicillin-resistant S. aureus showed a significant increase in the 10-year period (4.4%-42.9% of S. aureus isolates; P = 0.001). Haemophilus influenzae was the most frequent isolate recovered from patients under 7 years old (59.8%; P = 0.0002). There was a 3-fold increase in resistance of gram-positives to ciprofloxacin and oxacillin (P = 0.001). Overall, 9.5% of gram-positive isolates were resistant to gentamicin. Trimethoprim/sulfa showed a steady increase in resistance in gram-negative isolates (P = 0.05).
Conclusions: Staphylococcus aureus was the most common pathogen isolated. Methicillin-resistant S. aureus showed significant increasing prevalence. There were 2- and 3-fold increases in resistance of gram-positive organisms to erythromycin and ciprofloxacin, respectively. Gentamicin showed good sensitivity toward gram-positive pathogens.