Purchase this article with an account.
D. Miller, M. G. Diaz, E. M. Perez, R. K. Forster, E. C. Alfonso; Frequency and Spectrum of Mixed Bacterial/Nonbacterial Cornea Ulcers in South Florida. Invest. Ophthalmol. Vis. Sci. 2007;48(13):2683.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Mixed bacteria/nonbacterial keratitis is thought to be rare. The true prevalence however is not known or incompletely documented. Laboratory surveillance was implemented to establish rate of polymicrobial keratitis and occurrence of mixed bacteria/nonbacterial corneal ulcers among this group.
Microbiology reports were surveyed to identify polymicrobial corneal ulcers among culture positive patients presenting between January 2003 and October 2006. Culture positive rates, isolate frequency, smear positivity, and detection time were documented and compared for bacteria/bacteria (B/B) versus bacteria/nonbacterial (B/NB) co-infections. In vitro susceptibility coverage for the aminoglycosides and fluoroquinolones was assessed for bacteria/bacteria mixed infections
During the surveillance period, the frequency of polymicrobial ulcers was 5.7% (64/1115) and ranged 4.9% (2006) to 6.9% (2004). The ratio (B/B):B/NB) among polymicrobial ulcers was 2:1 (64.1% vs 32.8%). Combinations of HSV/Acanthamoeba and HSV/Nocardia (NB/NB, 3.1%) were isolated from two patients. The general culture positive rates were B/B -3.8% (41/1115), B/NB- 1.9% (21/1115) and NB/NB-.<1% (2/1115). A total of 142 isolates were recovered from the 64 cases. Three or more isolates were documented for 18.7% (12/64) of the cases. General pathogen recovery rates were gram negative (GN)-46.5%, gram positive (GP)-34.5% , filamentous fungi (FF)-7.7%, HSV-4.9%, Yeast (Y)-4.2% Acanthamoeba (AC)-1.4% and Nocardia (N) <1%. Isolate frequency among the B/B group included GN + GP - 61.2% (21/41), GN + GN-31.7% (13/41) and GP + GP-7.1% (7/41). Pathogens mix in the B/NB, group included HSV/B -26.1% (6/23), filamentous fungi/B -43.5% (10/23), yeast/B -26.1% (6/23) and Acanthamoeba -4.3% (1/23). Mixed infections were observed on smears for 25% (7/28) of B/B infections vs 14.3% (3/21) for B/NB (NS, p= 0.290, 95 CI). The second isolate in the B/B group were more likely (46% vs 26%) to be recovered from broth media than in the B/NB group (NS, p = 0.0913, 95 CI). At least one third of the isolates in the B/NB group were recovered after 72 hours (39%) vs (9.8%) for the B/B group (p=0.0189). Only 53.1% (61/115) of the isolate were susceptible to the aminoglycosides and or fluoroquinolones.
Mixed bacterial/nobacterial co-infections may be more frequent than reported. Laboratory studies should include a variety of media and be held greater than 72 hours. Empirical monotherapy may provided incomplete coverage for these infections.
This PDF is available to Subscribers Only