The effect of povidone–iodine on normal bacteria conjunctival flora in adult patients in Onitsha Nigeria

Abstract

Objectives: To determine the normal conjunctival flora and the effect of povidone–iodine on the flora in adult patients at the Guinness Eye Centre Onitsha Nigeria.

Materials and Methods: Each randomly recruited new adult patient had conjunctival swab taken from one eye; then a drop of 5% povidone–iodine solution was instilled on the conjunctiva. Conjunctival swabs were taken at 1, 5, and 10 min after povidone–iodine instillation. The swabs were smeared on glass slides and also inoculated unto MacConkey, chocolate, and nutrient agar. Microbial study of the specimens was undertaken.

Results: Of the 250 eyes of the 250 patients, 164 (65.6%) were culture-positive. A total of 225 organisms were isolated from the 164 culture-positive specimens as follows: Pseudomonas aeruginosa was isolated in 142 (63.1%), Staphylococcus epidermidis in 79 (35.1%), and Staphylococcus aureus in four (1.8%). Among the 61 specimens that grew more than one organism, 59 (96.7%) had a mixed growth of P. aeruginosa and S. epidermidis and 2 (3.3%) grew both S. epidermidis and S. aureus. Povidone–iodine significantly reduced the mean bacterial colony count in all bacterial isolates 10 min after instillation, that is: 114.4 to 35.7 for P. aeruginosa (P< 0.05), 71.7 to 15.8 for S. epidermidis (P< 0.05), and 45.5 to 3.0 for S. aureus (P<0.05). Bacterial colonies persisted in seven (2.8%) eyes 10 min after instillation of 5% povidone–iodine.

Conclusion: The normal conjunctiva of some patients harbor virulent bacteria, which load 5% povidone–iodine greatly reduced. These facts should be taken into consideration when planning intraocular surgery as part of the efforts to prevent endophthalmitis.

Keywords: Conjunctival bacteria flora, Nigeria, povidone–iodine