Abstract
Purpose:
To report incidence rates and antibiotic susceptibilities among gram-negative isolates from patients with endophthalmitis.
Methods:
Microbiology reports were reviewed to identify the incidence rates of gram negative pathogens (Enterobacteriaceae vs NonEnterobacteriaceae) recovered from endophthalmitis patients during a 25 year period (1990-2014). A combination of disk diffusion, Vitek 2 and Etests were used to susceptibility trends for amikacin, ceftazidime, and ciprofloxacin. Etests were used to evaluate moxifloxacin. Identifications were confirmed using conventional methods and Vitek 2.
Results:
In period I (1990-1999, period I) Gram negative pathogens represent 11.4% (n=125/1095) of the cases. Organism spectrum included: Enterobacteriaceae (32%, n=40/125). Top pathogens were Proteus mirabilis (n=12/30%), Serratia marcescens (n=8/20%), and Klebsiella pneumoniae (n=7/17.5%). NonEnterobacteriaceae were the predominant group -68% (n= 85/125). Top pathogens: Pseudomonas aeruginosa (41/48%), Haemophilus influenzae (n=15/17.6%) and Moraxella species (n=8/9.4%).<br /> In period II (2000-2014), gram negative pathogen frequency was 11.6% (n=121/1039), 75/62% were nonEnterobacteriaceae. Top pathogens were: Pseudomonas aeruginosa (n=37/49.3%), Haemophilus influenzae (15/20%), Moraxella osloensis (8/10.7%). For Enterobacteriaceae, the rate was 38% (n= 46). Serratia marcescens (n=16/34.8%), Enterobacter cloacae (9/19.6%), and Klebsiella pneumoniae (5/10.9%).<br /> Antimicrobial susceptibilities for Enterobacteriaceae from period I were: amikacin-80%; ceftazidime-83% and ciprofloxacin-89%. Non-Enterobacteriaceae: amikacin-100%; ceftazidime-90%; and ciprofloxacin-98%. Susceptibilities for Enterobacteriaceae from period II: amikacin, 95%; ceftazidime, 97%; and ciprofloxacin- 89%. Non-Enterobacteriaceae: amikacin, 84%; ceftazidime, 91%; and ciprofloxacin-98%.<br /> Moxifloxacin susceptibility for the Enterobacteriaceae (N=12) was 83% versus 41% for the Non-Enterobacteriaceae (N=17).<br /> The highest resistance and/or nonsusceptible trends for all pathogens were observed for moxifloxacin-41% (n=12/29), followed by amikacin (10%), ceftazidime (6%) and ciprofloxacin (4%).
Conclusions:
Gram negative isolates from patients with endophthalmitis have remained stable over the 25 year period. Emerging resistance trends to commonly used antibiotics amikacin, ceftazidime, ciprofloxacin and moxifloxacin have been identified.