Topical Antibiotics for Managing Bacterial Keratitis
Topical Antibiotics for Managing Bacterial Keratitis
Background Severe bacterial keratitis (BK) typically requires intensive antimicrobial therapy. Empiric therapy is usually with a topical fluoroquinolone or fortified aminoglycoside–cephalosporin combination. Trials to date have not reached any consensus as to which antibiotic regimen most effectively treats BK.
Methods A systematic review and meta-analysis using Cochrane methodology was undertaken to evaluate the effectiveness of topical antibiotics in the management of BK. Outcomes included treatment success, time to cure, serious complications of infection and adverse effects.
Results A comprehensive search for trials resulted in 27 956 abstracts for review. This eventually resulted in 16 high quality trials involving 1823 participants included in the review. Treatment success, time to cure and serious complications of infection were comparable among all antibiotic treatments included in the review. Furthermore, there was no evidence of difference in the risk of corneal perforation with any included antibiotics or antibiotic classes. Fluoroquinolones significantly reduced risk of ocular discomfort and chemical conjunctivitis but increased the risk of white precipitate formation compared with aminoglycoside–cephalosporin. Fortified tobramycin–cefazolin was approximately three times more likely to cause ocular discomfort than other topical antibiotics.
Conclusions Results of this review suggest no evidence of difference in comparative effectiveness between fluoroquinolones and aminoglycoside–cephalosporin treatment options in the management of BK. There were differences in safety profile, however. Fluoroquinolones decreased the risk of ocular discomfort and chemical conjunctivitis while ciprofloxacin increased the risk of white corneal precipitate compared with aminoglycoside–cephalosporin.
Bacterial keratitis (BK) remains a leading cause of ocular morbidity worldwide. The effects of BK range from mild corneal irritation to visual loss, corneal perforation or blindness. Severe infection may require hospitalisation and is typically treated with an intensive empiric regimen consisting of 15 min to hourly instillation of topical fortified aminoglycoside–cephalosporin (combination therapy) or topical fluoroquinolone (monotherapy), following corneal scrape and cultures. Severe bacterial infection may result in significant stromal scarring, which may eventually require corneal transplantation to restore vision.
While empiric treatment of BK is necessary when awaiting the outcome of culture and sensitivity testing, or where culture facilities are unavailable, the antibiotic regimen chosen should be of a sufficiently broad spectrum to cover likely pathogens while considering bacterial prevalence, antibiotic sensitivities and geographically-specific epidemiological data. In this respect, a systematic review investigating geographic variations in microbial keratitis highlighted major differences. USA (Los Angeles) and Australia (Adelaide) reported the highest percentages of bacterial cases (95% in both countries); Paraguay had the highest percentage of Staphylococcal infection (79%). Thailand (Bangkok) reported the highest percentage of Pseudomonas infections (55%) while India (Tamil Nadu) reported the highest percentage of Streptococcal infections (47%).
Despite the publication of numerous clinical trials, there remains a lack of consensus as to which topical antibiotics and which regimen (ie, monotherapy or combination therapy) provide superior clinical outcomes. Therefore, the objective of this systematic review was to quantify the comparative effectiveness and safety of various topical antibiotics for BK.
Abstract and Introduction
Abstract
Background Severe bacterial keratitis (BK) typically requires intensive antimicrobial therapy. Empiric therapy is usually with a topical fluoroquinolone or fortified aminoglycoside–cephalosporin combination. Trials to date have not reached any consensus as to which antibiotic regimen most effectively treats BK.
Methods A systematic review and meta-analysis using Cochrane methodology was undertaken to evaluate the effectiveness of topical antibiotics in the management of BK. Outcomes included treatment success, time to cure, serious complications of infection and adverse effects.
Results A comprehensive search for trials resulted in 27 956 abstracts for review. This eventually resulted in 16 high quality trials involving 1823 participants included in the review. Treatment success, time to cure and serious complications of infection were comparable among all antibiotic treatments included in the review. Furthermore, there was no evidence of difference in the risk of corneal perforation with any included antibiotics or antibiotic classes. Fluoroquinolones significantly reduced risk of ocular discomfort and chemical conjunctivitis but increased the risk of white precipitate formation compared with aminoglycoside–cephalosporin. Fortified tobramycin–cefazolin was approximately three times more likely to cause ocular discomfort than other topical antibiotics.
Conclusions Results of this review suggest no evidence of difference in comparative effectiveness between fluoroquinolones and aminoglycoside–cephalosporin treatment options in the management of BK. There were differences in safety profile, however. Fluoroquinolones decreased the risk of ocular discomfort and chemical conjunctivitis while ciprofloxacin increased the risk of white corneal precipitate compared with aminoglycoside–cephalosporin.
Introduction
Bacterial keratitis (BK) remains a leading cause of ocular morbidity worldwide. The effects of BK range from mild corneal irritation to visual loss, corneal perforation or blindness. Severe infection may require hospitalisation and is typically treated with an intensive empiric regimen consisting of 15 min to hourly instillation of topical fortified aminoglycoside–cephalosporin (combination therapy) or topical fluoroquinolone (monotherapy), following corneal scrape and cultures. Severe bacterial infection may result in significant stromal scarring, which may eventually require corneal transplantation to restore vision.
While empiric treatment of BK is necessary when awaiting the outcome of culture and sensitivity testing, or where culture facilities are unavailable, the antibiotic regimen chosen should be of a sufficiently broad spectrum to cover likely pathogens while considering bacterial prevalence, antibiotic sensitivities and geographically-specific epidemiological data. In this respect, a systematic review investigating geographic variations in microbial keratitis highlighted major differences. USA (Los Angeles) and Australia (Adelaide) reported the highest percentages of bacterial cases (95% in both countries); Paraguay had the highest percentage of Staphylococcal infection (79%). Thailand (Bangkok) reported the highest percentage of Pseudomonas infections (55%) while India (Tamil Nadu) reported the highest percentage of Streptococcal infections (47%).
Despite the publication of numerous clinical trials, there remains a lack of consensus as to which topical antibiotics and which regimen (ie, monotherapy or combination therapy) provide superior clinical outcomes. Therefore, the objective of this systematic review was to quantify the comparative effectiveness and safety of various topical antibiotics for BK.
