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Thomas Lietman

Publications and source records attributed to Thomas Lietman.

12 recordsLinked to original sources
PubMed2006

Hookworm infestation as a risk factor for Mooren's ulcer in South India.

OBJECTIVE: To investigate the association between Mooren's ulcer and intestinal hookworm infestation in South India. DESIGN: Prospective observational case-control study. PARTICIPANTS: Fifteen patients with Mooren's ulcer and 30 age- and gender-matched controls seen at Aravind Eye Hospital. METHODS: Stool samples from the Mooren's ulcer patients and controls were collected and analyzed for presence of hookworm infestation. MAIN OUTCOME MEASURE: Prevalence of hookworm infestation in Mooren's ulcer patients and controls. RESULTS: There was a statistically significant correlation between intestinal hookworm infestation and the occurrence of Mooren's ulcer (P = 0.009). Retrospective exploratory subgroup analyses suggested that the correlation between intestinal hookworm infestation and the occurrence of Mooren's ulcer in men (P<0.0001) was stronger than the correlation in women, with no statistically significant difference being observed in the prevalence of hookworm infestation between women with Mooren's ulcer and female control subjects (P>0.99). Similarly, when both the Mooren's ulcer and the control subject groups were analyzed retrospectively by age > 50 years or age < 50, subjects with an age over 50 demonstrated a stronger correlation between hookworm infestation and Mooren's ulcer than controls (P = 0.017), whereas there was no statistically significant difference in the prevalence of hookworm infection between Mooren's ulcer subjects and control subjects < or = 50 (P = 0.31). CONCLUSION: Intestinal hookworm infestation appears to be associated with the development of Mooren's ulcer in South India. Although the power of our retrospective exploratory subgroup analyses was limited by multiple testing and small sample sizes, these data suggest further that the correlation between intestinal hookworm infestation and the development of Mooren's ulcer may be greatest in male patients with more advanced age.

Adolescent↗
PubMed2006

Clinical characteristics of Mooren's ulcer in South India.

AIM: To describe the clinical characteristics at presentation of a large cohort of patients with Mooren's ulcer in South India. METHODS: The medical records of patients with Mooren's ulcer examined in the cornea clinic at Aravind Eye Hospital Madurai, Tamil Nadu, India, over a 10-year period were reviewed in this retrospective observational case series. RESULTS: The cohort contained 242 eyes of 166 patients. All patients were from South India, and men outnumbered women by a ratio of 4.7:1. The median and mean ages at presentation were 65 and 61 years, respectively, with a range of 13-95 years. One eye was affected in 90 of 166 (54%) patients. Visual acuity in the affected eye at presentation ranged from 6/6 to light perception, and was 6/12 or better in 34 of 242 (14%) eyes, between 6/12 and 3/60 in 168 (69%) eyes, and worse than 3/60 in 40 (17%) eyes. Partial peripheral corneal ulceration was observed in 222 (92%) eyes, complete peripheral corneal ulceration was observed in 15 (6%) eyes and total corneal ulceration was observed in 5 (2%) eyes. For those 222 eyes with partial peripheral ulceration, 152 (68%) showed temporal involvement, 129 (58%) showed nasal involvement, 116 (52%) showed inferior involvement and 30 (14%) showed superior involvement. Perforation was observed in 26 (11%) eyes, and was more common in eyes with peripheral as compared with total ulceration (p<0.001). Identified risk factors in the cohort included evidence of prior corneal surgery (22%), corneal trauma (17%) and corneal infection (2%). CONCLUSIONS: Mooren's ulcer is a rare and potentially blinding eye condition observed not infrequently in the cornea clinic at Aravind Eye Hospital. Men are affected more often than women and may present with either unilateral or bilateral disease. Perforation is observed in approximately 1 in 10 affected eyes at presentation and occurs most often in the setting of peripheral ulceration. The occurrence of prior corneal surgery, trauma or infection in nearly one third of patients supports theories of exposure to corneal antigen in the pathogenesis of this disorder.

Adolescent↗
PubMed2006

Correlation between clinical suspicion and polymerase chain reaction verification of infectious vitritis.

PURPOSE: To compare polymerase chain reaction (PCR) results to presumptive clinical diagnosis in patients with vitritis. DESIGN: Retrospective review of PCR laboratory records from vitreous samples. METHODS: Fifty consecutive laboratory records of vitreous samples sent for PCR testing were reviewed. Three reviewers with uveitis training ranked the clinical suspicion of a specific diagnosis using a classification system (scale of 1 to 4) and were masked to the PCR results. RESULTS: The degree of clinical suspicion of a particular diagnosis was significantly associated with a positive PCR result (P = .048). Higher clinical suspicion was significantly more associated with a positive PCR result compared with cases with lower clinical suspicion (P = .01). CONCLUSIONS: If the clinical suspicion of a specific diagnosis is low, the PCR for any infectious etiology is unlikely to be positive.

Adult↗
PubMed2004

How reliable is the clinical exam in detecting ocular chlamydial infection?

PURPOSE: To describe the relationship between the clinical exam for trachoma and the polymerase chain reaction (PCR) for ocular chlamydia. METHODS: One hundred children in a trachoma-endemic area of Ethiopia were examined three times and swabbed twice for PCR analysis. The assays were compared, and an analysis of the variance between exam and PCR was performed. RESULTS: Inter-examiner agreement was 0.57 (Cohen's kappa), inter-PCR agreement 0.98, and agreement between examiner and PCR, 0.26-0.34. The positive predictive value of the exam in identifying infection was 66%. Inter-examiner variance accounted for 30% of the total variance between the exam and PCR, with the remainder presumably due to an underlying difference in what the exam and PCR measure. CONCLUSIONS: Despite modest inter-grader reliability and correlation with evidence of infection, the clinical exam is widely used due to its convenience and low cost. Efforts to make laboratory tests for ocular Chlamydia trachomatis more affordable would be useful.

Child↗
PubMed2004

Trends in the etiology of infectious corneal ulcers at the F. I. Proctor Foundation.

OBJECTIVE: We analyzed laboratory results from corneal ulcers seen from 1976 to 1999 at the Francis I. Proctor Foundation, a referral center in San Francisco, to determine the relative frequencies of pathogens and to analyze for trends in frequencies of the most common pathogens. The results were compared with a previous study of corneal ulcers seen from 1948 to 1976 at the same institution. METHODS: Ulcers presenting to the Proctor Foundation were Gram stained and cultured using standard techniques. Herpetic corneal ulcers were excluded from the study. RESULTS: Organisms were isolated from 427 ulcers, 38% of all cases. Two hundred seventy-eight (59%) isolates were gram-positive bacteria, 145 (31%) gram-negative bacteria, 16 (3%) Acanthamoeba spp., and 36 (8%) fungi. Staphylococcus aureus was the most common organism, composing 20% of all isolates, followed by viridans group streptococci (12%), Streptococcus pneumoniae (11%), Pseudomonas aeruginosa (6%), Moraxella spp. (5%), and Serratia marcescens (4%). Over the 24-year study period the proportion of positive cultures decreased and the incidence of S. marcescens increased significantly. Comparing the period of 1948-1976 to 1976-1999, the frequency of S. pneumoniae and P. aeruginosa decreased, and that of S. marcescens increased significantly. CONCLUSION: The common pathogens associated with corneal ulcers have changed over the past 50 years in Northern California, with S. pneumoniae and P. aeruginosa being isolated relatively less often and S. marcescens being isolated with increasing frequency. The decrease in isolation of organisms over the 1976-1999 period may have resulted from increasing empiric antibiotic treatment by referring ophthalmologists.

Acanthamoeba↗
PubMed2004

Genetic diversity of Chlamydia trachomatis and the prevalence of trachoma.

BACKGROUND: Considerable variation in the outer membrane protein (ompA) of Chlamydia trachomatis has been uncovered by immunotyping and, more recently, by genotyping. This diversity may assist Chlamydia in evading the human immune system; organisms may have a competitive advantage if they infect a host who has previously been infected only by other strains. If so, a diverse set of strains may attain a higher prevalence in a community than a single strain. We determined the predominant strains of ocular C. trachomatis in trachoma-endemic villages of Nepal and tested the hypothesis that strain diversity is associated with the prevalence of infection. METHODS: Major outer membrane protein gene sequences of chlamydial isolates were determined from ligase chain reaction-positive eye swab samples collected from 10 villages. The diversity of genovars was determined for each village, using Simpson's index. RESULTS: Two genovar families (Ba and C) and nine genovars were detected, with a single genovar (C1) comprising more than one-half of the samples. The prevalence of clinically active trachoma was significantly associated with the genetic diversity in a village, controlling for village size and number of samples taken in a village. CONCLUSION: Genetic diversity of C. trachomatis is associated with the prevalence of infection in a community, consistent with the hypothesis that diversity may be necessary to attain a high prevalence in a community.

Base Sequence↗
PubMed2003

Eliminating trachoma in areas with limited disease.

The common wisdom is that a trachoma program cannot eliminate ocular chlamydia from a community, just reduce infection to a level where blindness would be minimal. We describe the success of multiple mass antibiotic treatments, demonstrating that complete elimination of infection may be an attainable goal in an area with modest disease.

Anti-Bacterial Agents↗
PubMed2002

Disappearance of trachoma from Western Nepal.

We assessed how much of the observed decline in the prevalence of trachoma in a district of Western Nepal was due to an antibiotic treatment program and how much to an underlying secular trend outside of the program. Although antibiotic treatments clearly have an effect at 6 months, we were unable to show that this effect persisted at 12 months; in fact, long-term gains may be due to a secular trend in the area.

Anti-Bacterial Agents↗
PubMed2002

Rapid assessment of trachoma in Hainan Province, China: validation of the new World Health Organization methodology.

This study was undertaken to validate a WHO methodology for the rapid assessment of trachoma. Fourteen villages were chosen by random sampling in two counties in Hainan Province, China. For the rapid assessment, trichiasis patients were identified, 50 children ages 1-10 years were examined for active trachoma, and information was collected on community access to services and community risk factors. To validate the methodology, a prevalence survey was undertaken simultaneously in the same villages. For the prevalence survey, 2428 people from 1606 households in the 14 villages were chosen by random sampling. Very little active trachoma was found by either method, although the rates of trichiasis were more substantial. Ranking of the villages by the two methods for trichiasis was highly correlated (Spearman's correlation coefficient = 0.60, p = 0.02). For active trachoma, the Spearman's correlation coefficient for the ranking of villages by the two methods was 0.40 and not significant (p = 0.14), suggesting that a correlation this close may have been seen by chance alone. The observational data showed all the villages to be at risk of active trachoma (due to poor environmental hygiene conditions), suggesting that this aspect of the WHO methodology overestimates the risk for active trachoma. We conclude that, with the exception of the community assessment of risk, this rapid assessment methodology is a valid tool for the assessment of trichiasis and possibly of active trachoma in rural communities, although the level of active trachoma in this study was too low to effectively validate that aspect of the methodology.

Child↗
PubMed2002

Does clinical diagnosis indicate ocular chlamydial infection in areas with a low prevalence of trachoma?

The WHO has initiated a global program to eliminate trachoma. This program includes mass antibiotic administrations to reduce the prevalence of Chlamydia trachomatis, the causative agent in trachoma. DNA amplification tests are the most sensitive methods to diagnose C. trachomatis infection, but are expensive and not typically performed in trachoma-endemic areas. Trachoma programs use clinical examination to determine which communities and which individuals within communities would benefit from antibiotic treatment, so understanding the relationship between clinical activity and chlamydial infection is important. In this study, we determine what percent of individuals with clinically active trachoma are infected with chlamydia in low prevalence communities of China and Nepal (with <10% clinical activity in children), and compare this against a high prevalence community of Nepal (with >30% clinical activity in children). In the low prevalence areas, only 8% clinically active cases had evidence of chlamydia. In the high prevalence community, 70% of clinically active cases harbored chlamydia. These results imply that clinical activity is less indicative of infection at a lower prevalence. In the context of a trachoma program, both clinically active cases and the community as a whole may stand to benefit less from antibiotic treatment in lower prevalence areas.

Adolescent↗