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Antibiotic prophylaxis 1 day or 1 hour before surgery reduces conjunctival bacterial flora
Flush irrigation of the conjunctival sac with povidone-iodine yielded the greatest reduction in preoperative bacterial flora.
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Topical antibiotics administered 1 day or 1 hour before cataract surgery significantly reduced the aerobic and microaerophilic conjunctival bacterial flora but had no significant effect on anaerobic bacteria, according to a study.
Irrigation with povidone-iodine was the most effective method of reducing the preoperative bacterial load and thus reducing the possible risk of postoperative endophthalmitis.
“The application of preoperative antibiotic eye drops given on the day before surgery or on the day of surgery only resulted in a similar reduction of the conjunctival bacterial flora,” Martin M. Nentwich, MD, the corresponding author, told Ocular Surgery News. “However, no effect of this antibiotic prophylaxis was seen on anaerobic bacteria.”
Study design, methods
The prospective, randomized study, published in the Journal of Cataract and Refractive Surgery, included 133 eyes of 133 patients. Sixty-four eyes (group 1) received four applications of topical 3,500 IU/mL of neomycin sulfate, 6,000 IU/mL of polymyxin B sulfate plus 1 mg/mL of dexamethasone and 0.04 mg/mL of benzalkonium chloride eye drops 1 hour before surgery. Sixty-nine eyes (group 2) underwent the same antibiotic regimen 1 day before surgery. Fellow eyes that did not undergo surgery served as controls.
Surgical staff used povidone-iodine 10% to perform periorbital disinfection in the preoperative holding area. A second round of periorbital disinfection and flush irrigation of the conjunctival sac using 10 mL povidone-iodine 1% of all surgery eyes was performed in the operating room.
Conjunctival specimens were collected at four time points: baseline (control eyes without topical antibiotics), after antibiotic prophylaxis but before irrigation, after irrigation and periorbital disinfection, and at the end of surgery (treated eyes). Specimens were inoculated onto blood and chocolate blood agar and in thioglycollate broth.
Results of prophylaxis
Aerobic and microaerophilic conjunctival flora were significantly reduced in study eyes compared with control eyes in both groups (group 1, P = .028; group 2, P = .000).
“Both prophylactic regimens were equally effective in reducing part of the conjunctival bacterial flora (aerobic and microaerophilic conjunctival flora),” Nentwich said. “However, both regimens had no significant effect on anaerobic bacteria.”
Flush irrigation of the conjunctival sac with povidone-iodine significantly reduced the conjunctival bacterial load in both groups.
“The greatest reduction was achieved by the use of povidone-iodine,” Nentwich said.
No eyes developed postoperative endophthalmitis, and no clinically significant adverse reactions to irrigation or swabbing were noted.
Additional observations
Nentwich noted that intracameral antibiotics offer additional clinical benefits in complicated cases.
“It is known that the risk of postoperative endophthalmitis is increased in cases of complicated cataract surgery with prolonged duration of surgery and more intense intraoperative manipulation and complications such as a posterior capsule tear,” he said. “Especially in these cases, the additional use of intracameral antibiotics at the end of surgery should be considered as an additional preventive measure. The most important step in endophthalmitis prophylaxis remains diligent preoperative prophylaxis with povidone-iodine including a flush irrigation of the conjunctival sac.”
Nentwich also said that same-day preoperative antibiotic prophylaxis reduces patient burdens and medical costs.
“By limiting the preoperative antibiotic prophylaxis to the day of surgery, the patients do not need to buy any medication before surgery,” Nentwich said. “They do not have to apply any drops themselves before surgery, as the drops given on the day of surgery were applied during the preparation measures before surgery and given by medical personnel. Especially in the older age cataract surgery population, application of eye drops may be difficult. Thus, limiting the necessary duration of use increases patients’ comfort.” – by Matt Hasson
Reference:
Li B, et al. J Cataract Refract Surg. 2015;doi:10.1016/j.jcrs.2014.06.042.For more information:
Martin M. Nentwich, MD, can be reached at Department of Ophthalmology, Ludwig-Maximilians University, Munich, Germany; email: martin.nentwich@med.uni-muenchen.de.Disclosure: Nentwich reports no relevant financial disclosures.
Perspective
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Douglas R. Lazzaro, MD, FACS
In their study, Li and colleagues discuss the prophylactic efficacy of four topical doses of antibiotic used over 1 hour (group 1) or 1 day (group 2) before surgery to reduce conjunctival bacteria culture rates. The regimen was used before topical povidone-iodine in all surgery eyes, a known disinfectant currently used to reduce the incidence of postoperative endophthalmitis after cataract surgery. The authors correctly point out the conjunctival bacteria culture rates do not necessarily imply reduced endophthalmitis rates.
The prospective study included 133 eyes. Cultures were taken from the unoperated control eye, after topical antibiotic regimen in both groups but before topical povidone-iodine, after povidone-iodine and lastly at conclusion of surgery. The reduction of positive cultures in control eyes vs. study eyes after antibiotic prophylaxis was statistically significant in both groups.
A statistically significant reduction in aerobic and microaerophilic bacteria was found in both groups with topical antibiotic. However, there was no statistically significant effect on anaerobic bacteria, such as P acnes. Postoperatively, cultures were positive in five eyes (7.8%) in group 1 and six eyes (8.7%) in group 2. In reference to this last statement, the authors point out that intracameral antibiotic injection at the conclusion of surgery may be advantageous.
The authors summarize by stating that the use of topical antibiotics only on the day of surgery reduces health care cost burden vs. a day or days before surgery, but that independent of the duration of topical antibiotic prophylaxis (1 day vs. 1 hour), povidone-iodine was still the most effective preoperative measure in reducing the preoperative conjunctival bacterial load.
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