Risks for Treating Bacterial Keratitis With Fluoroquinolone-Based Monotherapies

Abstract

 

Purpose:

 

Visual outcome of patients presenting bacterial keratitis (bac-k) can be seriously engaged if the appropriate treatments are not administered on-time. In France, around 5000 bac-k are documented yearly, with Gram+ cocci in 50 to 90% of cases and Gram- rods in 10 to 50% according to different series. The objective of this work was to study the susceptibility of 100 strains isolated (2007-2008) at the National Eye Center in Paris (CHNO) from patients with bac-k to 3 fluoroquinolones (FQ).

 

Methods:

 

Bacterial strains were isolated and tested for their susceptibilities to 3 FQ (ciprofloxacine, levofloxacine and norfloxacine) using the Kirby-Bauer disc diffusion test.

 

Results:

 

The species isolated were: 23 % negative coagulase Staphylococci (1 methicillin resistant), 17 % S. aureus (1 methicillin resistant), 12 % Streptococcus pneumoniae, 13 % S. sanguis, 19 % Pseudomonas aeruginosa, 11 % Serratia marcescens and 5 % Haemophilus influenzae. The results of the antibiotic susceptibility testing are presented hereafter

 

Conclusions:

 

Very frequently, ophthalmologists have to decide to administrate empiric treatments before the antibiotic susceptibility testing are available. The results obtained in this survey should warn on the risks -especially for negative coagulase Staphylococci and for Streptococci- of treating bac-k with empiric monotherapies. This study confirms our previous observations suggesting that before results of antibiotic susceptibility testing are available, treatments of bac-k require at least two broad spectrum antibiotics acting each one at different molecular targets of the bacteria.  

 

Keywords: keratitis • antibiotics/antifungals/antiparasitics • clinical laboratory testing