Antibiotics versus control for toxoplasma retinochoroiditis
Abstract
Background
Acute toxoplasma retinochoroiditis causes transient symptoms of ocular discomfort and may lead to permanent visual loss. Antibiotic treatment primarily aims to reduce the risk of permanent visual loss, recurrent retinochoroiditis and the severity and duration of acute symptoms. There is uncertainty about the effectiveness of antibiotic treatment.
Objectives
To compare the effects of antibiotics versus placebo or no treatment for toxoplasma retinochoroiditis.
Search methods
We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2011, Issue 1), MEDLINE (January 1950 to February 2011), EMBASE (January 1980 to February 2011), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to February 2011), the metaRegister of Controlled Trials (mRCT) (www.controlled‐trials.com) (February 2011) and ClinicalTrials.gov (www.clinicaltrials.gov) (February 2011). We also searched the archived National Research Register (NRR) and the UK Clinical Research Network Portfolio Database (UKCRN) on 23 January 2008. Dissertation Abstracts was last searched in June 2001, PASCAL was last searched in March 2000 and proceedings of the Association for Research in Vision and Ophthalmology was searched from 1980 to 2001, we also searched international symposia on uveitis. We searched the reference lists of identified articles and contacted pharmaceutical companies for unpublished trials. There were no language or date restrictions in the search for trials. The electronic databases were last searched on 7 February 2011.
Selection criteria
We included randomised controlled trials that compared any systemic antibiotic treatment against placebo or no treatment. Trials that included immunocompromised patients were excluded.
Data collection and analysis
The primary outcomes for this review were visual acuity at least three months after treatment and risk of recurrent retinochoroiditis. Secondary outcomes were improvement in symptoms and signs of intraocular inflammation, size of lesion and adverse events. Effect measures were pooled using a random‐effects model.
Main results
Three trials which randomised a total of 173 participants met the inclusion criteria. All trials were methodologically poor. None reported the effect of treatment on visual acuity. Two studies reported results for recurrent retinochoroiditis: one (124 participants) found a significant reduction in participants in Brazil with chronic recurrent disease who were treated for 14 months (risk ratio (RR) 0.29, 95% confidence interval (CI) 0.10 to 0.81); the other (20 participants) found no evidence of an effect in participants with acute toxoplasma retinochoroiditis (RR 1.00, 95% CI 0.07 to 13.87). Two studies reported an improvement in intraocular inflammation in treated compared with untreated participants and one study reported no difference. Two studies found an increased risk of adverse events in treated participants.
Authors' conclusions
There is a lack of evidence to support routine antibiotic treatment for acute toxoplasma retinochoroiditis. There is weak evidence to suggest that long‐term treatment may reduce recurrence of retinochoroiditis in patients with chronic recurrent toxoplasma retinochoroiditis due to more virulent South American strains of Toxoplasma gondii. Placebo controlled trials of patients with acute and chronic toxoplasma retinochoroiditis affecting any part of the retina are required to determine the effectiveness of antibiotic treatment.
PICOs
Plain language summary
Antibiotics compared with no treatment or placebo for the treatment of toxoplasma retinochoroiditis
Toxoplasma retinochoroiditis occurs when a parasite called toxoplasma gondii gets into the retina (the light sensitive layer inside the eye) and the choroid (layer of the eyeball near the retina). This causes inflammation that can scar the retina and reduce vision. Symptoms include a sudden feeling of discomfort in the eye and loss of vision which usually resolve spontaneously within six to eight weeks. The infection can keep returning, increasing the chances of damage. Antibiotics are sometimes used to try and reduce the inflammation and scarring, or to prevent the infection from re‐emerging, but it is not known how well they work. The review found three studies with a total of 173 participants of any age which compared antibiotics with no treatment or a placebo. Two studies examined the effect of antibiotics on reducing the recurrence of episodes of the disease. One study found that in Brazilian adults infected with the more aggressive South American strains of the parasite who have frequently recurring eye symptoms, long‐term antibiotics over 14 months reduced the number of recurrent episodes of retinochoroiditis. The second study did not find that short‐term treatment with antibiotics made any difference. Side effects of giving antibiotics such as decreased white blood cells, loss of appetite, rashes and other allergic reactions, were investigated in two studies involving the antibiotic pyrimethamine: only weak evidence was found that antibiotics increase the risk of side effects. In all studies, there were problems with the design, conduct and analyses, which could have biased the results. There was a lack of evidence about whether antibiotics (short‐ or long‐term) prevent vision loss. More trials are needed, including trials of newer antibiotics.
