Rapid quantitative serological test for detection of infection with Mycobacterium leprae, the causative agent of leprosy.

Leprosy remains an important health problem in a number of regions. Early detection of infection, followed by effective treatment, is critical to reduce disease progression. New sensitive and specific tools for early detection of infection will be a critical component of an effective leprosy elimination campaign. Diagnosis is made by recognizing clinical signs and symptoms, but few clinicians are able to confidently identify these. Simple tests to facilitate referral to leprosy experts are not widely available, and the correct diagnosis of leprosy is often delayed. In this report, we evaluate the performance of a new leprosy serological test (NDO-LID). As expected, the test readily detected clinically confirmed samples from patients with multibacillary (MB) leprosy, and the rate of positive results declined with bacterial burden. NDO-LID detected larger proportions of MB and paucibacillary (PB) leprosy than the alternative, the Standard Diagnostics leprosy test (87.0% versus 81.7% and 32.3% versus 6.5%, respectively), while also demonstrating improved specificity (97.4% versus 90.4%). Coupled with a new cell phone-based test reader platform (Smart Reader), the NDO-LID test provided consistent, objective test interpretation that could facilitate wider use in nonspecialized settings. In addition, results obtained from sera at the time of diagnosis, versus at the end of treatment, indicated that the quantifiable nature of this system can also be used to monitor treatment efficacy. Taken together, these data indicate that the NDO-LID/Smart Reader system can assist in the diagnosis and monitoring of MB leprosy and can detect a significant number of earlier-stage infections.

Quantification of yeast and bacterial gene transcripts in retail cheeses by reverse transcription-quantitative PCR.

The cheese microbiota contributes to a large extent to the development of the typical color, flavor, and texture of the final product. Its composition is not well defined in most cases and varies from one cheese to another. The aim of the present study was to establish procedures for gene transcript quantification in cheeses by reverse transcription-quantitative PCR. Total RNA was extracted from five smear-ripened cheeses purchased on the retail market, using a method that does not involve prior separation of microbial cells. 16S rRNA and malate:quinone oxidoreductase gene transcripts of Corynebacterium casei, Brevibacterium aurantiacum, and Arthrobacter arilaitensis and 26S rRNA and beta tubulin gene transcripts of Geotrichum candidum and Debaryomyces hansenii could be detected and quantified in most of the samples. Three types of normalization were applied: against total RNA, against the amount of cheese, and against a reference gene. For the first two types of normalization, differences of reverse transcription efficiencies from one sample to another were taken into account by analysis of exogenous control mRNA. No good correlation was found between the abundances of target mRNA or rRNA transcripts and the viable cell concentration of the corresponding species. However, in most cases, no mRNA transcripts were detected for species that did not belong to the dominant species. The applications of gene expression measurement in cheeses containing an undefined microbiota, as well as issues concerning the strategy of normalization and the assessment of amplification specificity, are discussed.

[Reliability and agreement of two smear reading scales for classification and monitoring of multidrug therapy in leprosy patients]. / Confiabilidad y concordancia de dos escalas de lectura de baciloscopias para clasificación y seguimiento del tratamiento con múltiples medicamentos de los pacientes con lepra.

INTRODUCTION: After the clinical diagnosis of leprosy, classification methods are necessary to define a treatment and prognosis of patients consistent with bacterial load. Bacteria are detected in skin smear, and bacterial load typically is established by the internationally used Ridley's logarithmic scale, However, in Colombia an alternative semiquantitative scale is used. OBJECTIVE: The interobserver reproducibility was established for the Ridley and Colombia scales, and the level of correlation-matching was identified between the bacillary indices obtained in order to assess the degree of interchangeability. MATERIALS AND METHODS: Standardization was attained by a reading of the smears by 2 readers with subsequent, blinded evaluation of inter-observer agreement. Each reader quantified the bacterial load of for each sample (n=325) using the Colombian and the Ridley scales. The degree of interobserver agreement was assessed with weighted kappa coefficient. The level of correlation and agreement between the measurements of the bacillary index was established with coefficient of Lin. RESULTS: The interobserver weighted kappa coefficient was 0.83 for the Colombia scale and 0.85 for the Ridley scale. The Lin coefficient was 0.96 for the correlation-matching of bacillary indexes. CONCLUSIONS: Interobserver agreement obtained for both scales was excellent as the correlation-matching bacillary indices determined with both methods. With the cut-off points yielded a good level of agreement, ensuring interchangeability between the scales defining the high or low bacterial load.