Methicillin resistance of Staphylococcus species among health care and nonhealth care workers undergoing cataract surgery

Abstract

Purpose: The purpose of this study is to characterize the bacterial flora of the ocular and periocular surface in cataract surgery patients and to determine the prevalence of methicillin resistance among staphylococcal isolates obtained from health care workers (HCWs) and non-HCWs.

Methods: In this prospective, multicenter, case series study, eyelid and conjunctival cultures were obtained from the nonoperative eye of 399 consecutive cataract patients on the day of surgery prior to application of topical anesthetics, antibiotics, or antiseptics. Speciation and susceptibility testing were performed at the Dean A. McGee Eye Institute. Logistic regression was utilized to evaluate whether any factors were significant in predicting the presence of methicillin-resistant staphylococcal isolates.

Results: Staphylococcus epidermidis (62.9%), followed by S. aureus (14.0%), was the most frequently isolated organism. Methicillin-resistant S. epidermidis accounted for 47.1% (178/378) of S. epidermidis isolates, and methicillin-resistant S. aureus accounted for 29.5% (26/88) of S. aureus isolates. Methicillin-resistant staphylococcal isolates were found in 157 of 399 (39.3%) patients, the majority (89.2%) of whom were non-HCWs. The likelihood of being colonized with methicillin-resistant organisms increased with age (odds ratio [OR], 1.27; 95% confidence interval [CI]: 1.02-1.58; P = 0.04) but decreased with diabetes (OR, 0.51; 95% CI: 0.29-0.89; P = 0.02). Being a HCW (OR, 1.25; 95% CI: 0.61-2.58; P = 0.54) was not a risk factor for colonization with methicillin-resistant organisms.

Conclusion: Patients without exposure to health care environments are as likely as HCWs to be colonized with methicillin-resistant organisms. Increasing methicillin resistance with age may partially explain the increased risk of endophthalmitis reported with older age.

Keywords: Staphylococci; age; bacterial flora; cataract surgery; methicillin resistance; ocular and periocular surface.

Figures

Figure 1A

Bacterial species on the lids and conjunctiva of cataract surgery patients. Notes: aIncluded S. hominis (n = 6; 1.5%), S. saprophyticus (n = 3; 0.8%), Streptococcus species (n = 3; 0.8%), S. sciuri (n = 2; 0.5%), S. lentus (n = 2; 0.5%), S haemolyticus (n = 2; 0.5%), S. caprae (n = 2; 0.5%), and S. cohnii spp urealyticus (n = 1; 0.3%); bIncluded Enterobacter agglomerans (n = 5; 1.3%), Serratia marcescens (n = 2; 0.5%), Kiebsiella ozaenae (n = 2; 0.5%), Enterobacter aerogenes (n = 1; 0.3%), Escherichia coli (n = 1; 0.3%), Acinetobacter lwoffii (n = 1; 0.3%), Kocuria varianslrosea (n = 1; 0.3%), and Shigella (n = 1; 0.3%).

Figure 1 B

Bacterial species on the lids and conjunctiva of cataract surgery patients. Notes: aIncluded S. hominis (n = 4; 1.6%), S. caprae (n = 3; 1.2%), S. haemolyticus (n = 3; 1.2%), S. xylosus (n = 2; 0.8%); bIncluded Kocuria varians/rosea (n = 2; 0.8%), Kocuria kristinae (n = 1; 0.4%), Enterobacter aerogenes (n = 1; 0.4%), Enterobacter cloacae (n = 1; 0.4%), Klebsiella pneumoniae (n = 1; 0.4%), Serratia marcescens (n = 1; 0.3%).

Figure 2A

Oxacillin (methicillin) susceptibility of lid and conjunctival Staphylococcus species. Notes: aFour (7%) S. aureus isolates, 2 (1.O%) S. epidermis isolates, 1 (50%) S. saprophyticus isolate, and 1 (12%) S. warneri isolate were intermediately resistant to oxacillin.

Figure 2B

Oxacillin (methicillin) susceptibility of lid and conjunctival Staphylococcus species. Notes: aFour (3%) S. epidermis isolates, 1 (3%) S. aureus isolate, and 1 (33%) S. caprae isolate were immediately resistant to oxacillin.