Bacterial Species and Surgical Sites Involved in Contamination During Strabismus Surgery

Residual bacterial colonization of the eye after strabismus surgery is common. This study aimed to identify the bacterial pathogens and contaminated sites involved during strabismus surgery.

A prospective, case-control study of 44 patients aged 1-78 years who underwent strabismus surgery.

Before participation, we received clinical research board approval, and informed consent was obtained from each of the patients or the parents. Five percent povidone-iodine was used to sterilize the surgical site in all cases. Intraoperative swabs were taken from conjunctival incision site, plain gut suture, scleral surgery site, Vicryl suture, and lid specula. Bacteria isolates were identified by culture growth and Gram staining. Positive and negative control samples were collected.

Samples from 13 (29.5%) of 44 cases were positive for growth of bacteria. The conjunctival incision site was involved in 9 cases (20.5%), and the lid speculum in 7 cases (15.9%). All 13 colonized plates grew the coagulase-negative Staphylococcus strain. Staphylococcus aureus was cultured in 1 case (2.3%) and was associated with the only case of postoperative infection. The S. aureus cultures came from both the conjunctival incision site and the lid speculum.

Despite a high contamination rate of 29.5%, incidence of clinically significant infection was low. Our study suggests involvement of the eyelids and conjunctiva in harboring bacteria even after the use of povidone-iodine. Regardless of the mechanism of contamination, we should continue to focus our efforts on reducing intraoperative conjunctival bacterial load. Irregular tear film can contribute to postoperative complications.