Introduction: Bacterial conjunctivitis is a self-limiting process, but topical antibiotic treatment is recommended to eradicate the pathogen and reduce symptom duration. Since this treatment is usually empirical and prior cultures are not normally taken, the etiological agents involved in the process are unknown.
Patients and methods: A total of 596 conjunctival exudates from pediatric outpatients with a diagnosis of acute conjunctivitis in Medical Area 6 of Madrid, Spain, were studied over 3 years (from 2000 to 2002 inclusive). The patients were divided into three age groups: group 1 (infants), group 2 (2- to 6-year-olds) and group 3 (7- to 14-year-olds).
Results: A total of 428 bacteria were isolated. The most prevalent bacteria were Haemophilus influenzae (44.8 %) and Streptococcus pneumoniae (30.6 %) followed by Staphylococcus aureus (7.5 %), S. viridans (7.2 %), Moraxella catarrhalis (6.8 %) and Enterobacteriaceae (4.2 %). In 56 exudates (15.1 %), two or more bacteria were isolated and S. pneumoniae 1 H. influenzae were found in 8.1 % of the cases. By age group, S. aureus was significantly more prevalent (p < 0.0001) in group 3 than in groups 1 and 2. Isolation of Enterobacteriaceae, S. viridans and non-fermentative Gram negative bacilli was significantly more frequent (p < 0.05) in group 1 and isolation of S. pneumoniae (p < 0.05) was significantly more frequent in group 2. S. pneumoniae showed the greatest level of resistance to antibiotics used in eye drops and ophthalmic ointments. Ciprofloxacin, chloramphenicol and rifampin were active in the most prevalent pathogens.
Conclusions: The most prevalent bacteria were H. influenzae and S. pneumoniae. The most active antibiotics in these pathogens were ciprofloxacin, chloramphenicol and rifampin.