Abstract
Purpose :
Intravitreal injections have recently been used in pre-term infants to treat high-risk retinopathy of prematurity (ROP). There is no direct evidence on the efficacy of topical antiseptic preparation in reducing the conjunctival bacterial load in this unique patient population. This study evaluated the composition of the bacterial flora and antibiotic resistance patterns, as well as the effect of povidone-iodine (PI) on the conjunctival bacterial load in pre-term infants screened for ROP.
Methods :
Conjunctival cultures were obtained from a randomly selected eye of 10 pre-term infants during routine ROP examinations. Samples were collected (ESwab™) from the conjunctiva before and 2 minutes after instillation of two drops of 5% PI. The samples were sent to the microbiology laboratory at Children’s Hospital of Wisconsin for gram stain, culture, species identification, and quantification of colony-forming units (CFU). The organism isolates were also tested for minimum inhibitory concentration to the following antibiotics: erythromycin, ofloxacin, polymixin B, moxifloxacin, and tobramycin.
Results :
Cultures were positive in 90% of subjects. The most commonly isolated organism in this study was Staphylococcus epidermidis (50%), followed by Streptococcus mitis (20%), Corynebacterium species (20%), Staphylococcus hominis (10%), Gemella haemolysans (10%), viridans streptococci (10%), and coagulase-negative staphylococci, unspeciated (10%). One subject yielded polymicrobial growth. After exposure to PI, 70% of subjects were culture-positive, and 20% of subjects were found to have new organism isolates. CFU counts decreased for 82% of organism isolates and increased for 9% following PI exposure. Antibiotic resistance of organisms to erythromycin, ofloxacin, polymixin B, moxifloxacin, and tobramycin was 47%, 32%, 21%, 5%, and 0% respectively.
Conclusions :
Drop instillation of 5% PI lowers the CFU count of conjunctival samples, but may not significantly reduce the positive culture rate in pre-term infants screened for ROP in the neonatal intensive care unit. More studies are needed to compare the efficacy of more extensive antiseptic preparation of the eyelids and conjunctiva and antibiotic prophylaxis in this population.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.