Infectious keratitis: trends in microbiological and antibiotic sensitivity patterns.

OBJECTIVES: To report the spectrum and trends of isolated microorganisms and their antibiotic susceptibility profile in patients with infectious keratitis in a 6-year period at a referral centre in Tehran. METHODS: The microbiology records of all corneal scrapings with a diagnosis of infectious keratitis were reviewed. RESULTS: A total of 6282 corneal scrapings were performed during the study period, of which 2479 (39.5%) samples were culture positive. Pseudomonas aeruginosa was found to be the most common causative agent in patients with keratitis, although Streptococcus pneumonia was the most prevalently isolated microorganism in patients older than 50 years. Fusarium sp. was the most common responsible pathogen in patients with fungal keratitis. The prevalence of bacterial keratitis due to gram positive microorganisms increased over time, however the number of Pseudomonas keratitis decreased in the second half of the study. Gram negative organisms showed a good sensitivity to levofloxacin, however, 34.1% of S. aureus isolates and 29.7% of coagulase negative staphylococci were resistant to this antibiotic. The odds of ciprofloxacin and levofloxacin resistance increased 1.25 and 1.15 for each 1-year increase in culture date, respectively (P < 0.001, P = 0.004). CONCLUSIONS: We documented an increasing trend in the percentage of gram positive bacteria. Levofloxacin monotherapy might still be a good option in patients with gram negative bacterial keratitis, however owing to increasing resistance of staphylococci to fluoroquinolones, a regimen consisting of a combination of fortified antibiotics may be more effective in staphylococcal keratitis.

Serological and molecular approaches in clinical diagnosis of ocular toxoplasmosis in Iran.

Background: Toxoplasma gondii (T. gondii) is the most common parasite that can lead to a disease called toxoplasmosis. In this study, serological and molecular complementary tests have been conducted to detect or diagnose this parasite. Methods: A total of 71 patients with clinical symptoms of ocular toxoplasmosis and 20 patients with other ocular infections were evaluated. Serum and buffy coat samples were collected and tested using enzyme-linked immunosorbent assay (ELISA) and nested polymerase chain reaction (nPCR) assessments. Superficial T. gondii B1 gene was evaluated in PCR. The ocular toxoplasmosis patients were followed-up 2 weeks after the first sampling and 4 weeks following the first laboratory testing. The main outcome measures were the efficiency of the diagnostic procedure and positive and negative predictive values (PPV and NPV). Results: Overall, of the samples, 69% were PCR+, IgG+, and IgM-, and 4.2% showed PCR+, IgG+, and IgM+. In the first follow-up, after 2 weeks, from the 41 referred patients, 29 (70%) showed PCR+, IgG+, and IgM-, which confirmed the results of the first sampling. In the second follow-up, 9 (47%) patients were PCR+, IgG+, and IgM-. A correlation was observed between the first referral and the follow-ups. Also, from 71 patients, diagnosed clinically as ocular toxoplasmosis, the disease was confirmed in 73.2% and 26.8% of those suffering from other ocular infections. Of the 20 control group samples, 55% showed PCR-, IgG+, and IgM-. The sensitivity, specificity, negative and positive predictive values, and negative and positive likelihoods were analyzed for IgG and IgM antibodies and for PCR using ELISA method. Conclusion: As the ophthalmologic signs of T. gondii may be mimicked by other infections, clinical methods may be complemented by laboratory approaches for a definite diagnosis. This would assist clinicians to achieve timely diagnosis and successful therapy and to control the infection.