Antibiotic resistance of conjunctiva and nasopharynx evaluation study: a prospective study of patients undergoing intravitreal injections.

PURPOSE

To determine the baseline antibiotic susceptibility patterns of conjunctival and nasopharyngeal flora isolated from patients undergoing intravitreal (IVT) injections for choroidal neovascularization (CNV).

DESIGN

Prospective, observational study.

PARTICIPANTS

Forty-eight eyes of 24 patients undergoing unilateral IVT injections for CNV.

METHODS

Bilateral conjunctival and unilateral nasopharyngeal cultures on the treatment side were taken before application of any topical medications.

MAIN OUTCOME MEASURES

Bacterial isolates were identified and tested for antibiotic susceptibility to 16 different antibiotics using the Kirby-Bauer disc diffusion technique.

RESULTS

A total of 57 bacterial isolates were obtained from the conjunctiva of 48 eyes. Coagulase-negative staphylococci (CNS) accounted for 37 of the 57 isolates (65%). The most common CNS organisms were Staphylococcus epidermidis and Staphylococcus lugdunensis accounting for 73% and 11% of CNS isolates, respectively. More than half of S. epidermidis isolates demonstrated some level of resistance to ofloxacin and levofloxacin, and 33% and 37% of isolates showed some level of resistance against gatifloxacin and moxifloxacin, respectively. Some 60% and 30% of CNS isolates were resistant to ≥ 3 and ≥ 5 antibiotics, respectively. Among the 24 nasopharyngeal cultures, 8 (33%) grew Staphylococcus aureus, and 1 of the 8 isolates (13%) was resistant to all penicillin, cephalosporin, macrolide, and fluoroquinolone antibiotics tested.

CONCLUSIONS

Our results demonstrate subtantial levels of resistance to third- and fourth-generation fluoroquinolones and multiresistance among ocular CNS isolated from patients undergoing IVT injections for CNV.