P0306 - Characteristics and Outcomes of Pediatric Polybacterial Conjunctivitis Infections in Studies with Besifloxacin Ophthalmic Suspension 0.6%

Purpose: Bacterial conjunctivitis can be due to infection with more than one bacterial pathogen. We identified pediatric patients with polybacterial infections at baseline in clinical studies of besifloxacin ophthalmic suspension 0.6% administered 3 to 7 days in the treatment of bacterial conjunctivitis and report on baseline characteristics and outcomes in this population.

Methods: This was a post-hoc analysis of data from five previously conducted multicenter randomized clinical studies (four vehicle- and one active-controlled). In each of these studies, conjunctival swabs were taken at baseline and two follow-up visits, and the same central laboratory was used to culture and identify bacterial species in swabs. To avoid attribution of conjunctivitis to normal commensal microflora, isolates were classified as causative only if their colony count (in CFU/mL) equaled or exceeded species-specific pre-specified threshold criteria. Subjects aged 1 through 17 years with polybacterial infections at baseline were identified across the studies, and baseline microbiological data and clinical microbial eradication rates were extracted for analyses. The fold-increase in colony count over threshold was used to rank order the contribution of each causative species.

Results: Of 730 pediatric subjects with culture-confirmed conjunctivitis across the studies, 172 (23.6%) had polybacterial infections at baseline. The mean (±SD) age of these subjects was 5.0 (±4.3) years, and 49% were female; 73.3% were infected with two species, 19.8% with three, and 7.0% with four or more. Compared to subjects with monobacterial infections, a greater proportion of subjects with polybacterial infections also had viral infections (5.2% vs 1.6%; P=0.007, CMH test). Haemophilus influenzae was the most common dominant causative species in polybacterial infections followed by Streptococcus pneumoniae. Moraxella catarrhalis and Streptococcus mitis/S. mitis group occurred more often whereas S. pneumoniae occurred half as often as dominant causative species among polybacterial compared to monobacterial infections (P≤0.032 for all, Fisher’s exact test). The most common secondary co-infecting species (based on rank order) in polybacterial infections were Staphylococcus aureus and S. mitis/S. mitis group. Treatment of polybacterial infections with besifloxacin led to significantly greater bacterial eradication rates compared to vehicle at the first follow-up visit (75.2% vs 45.8%; P<0.001 χ2test).

Conclusions: Nearly one in four pediatric subjects enrolled in studies evaluating besifloxacin 0.6% for the treatment of bacterial conjunctivitis had a polybacterial infection at baseline. Treatment with besifloxacin was effective in eradicating these mixed organism infections attesting to the broad-spectrum activity of this chloro-fluoroquinolone.