RAPD discloses high molecular diversity of Mycobacterium tuberculosis from Michoacan, Mexico.

Random amplified polymorphism DNA (RAPD) is an easy, inexpensive technique for the characterization of pathogens in low-income countries. In this study we used RAPD to assess the genetic diversity of a small collection of isolates of mycobacteria from the Mexican state of Michoacan. In contrast with the low annual tuberculosis incidence in Michoacan relative to the national average, we found a high molecular diversity value suggesting high population diversity of M. tuberculosis in the studied region. Our findings justify further typing efforts with other molecular tools such as MIRU-VNTR and spoligotyping.

Genetic diversity among Mycobacterium tuberculosis isolates from Mexican patients.

Forty-six isolates of the Mycobacterium tuberculosis complex were typified by PCR of the IS6110 region and by Mycobacterium bovis specific primers JB21/JB22. Isolate MVG01 was typified as M. bovis, being the first record of a case of human tuberculosis caused by this species in Mexico. RAPD-PCR was used to describe the genetic diversity of the remaining 45 M. tuberculosis complex isolates. The corrected genotypic diversity value calculated for the analyzed population was 0.96, the estimated mean gene diversity was 0.235, and the corrected Shannon-Weiner index was 2.15. All allele-loci combinations generated showed significant linkage disequilibria. The distribution of genetic variation was analyzed both by the unweighted pair group method with arithmetic averages clustering and by principal coordinates analysis. Unweighted pair group method with arithmetic averages clustering resulted in a tree with four main clusters and one unclustered strain (MVG20), the principal coordinates analysis strain distribution pattern being consistent with this grouping. The obtained results suggest that the studied isolates belong to a clonal population having significant genetic diversity. Our genetic diversity results are comparable with those reported for other populations of M. tuberculosis, although only three RAPD primers were used.

Determination of alpha- and beta-amanitin in clinical urine samples by Capillary Zone Electrophoresis.

Amanitins are toxins found in species of the mushroom genera Amanita, Lepiota and Galerina. Intoxication after ingestion of these mushrooms can be fatal with an estimated 20% of mortality rate. An early diagnosis is necessary in order to avoid invasive and expensive therapy and to improve patient's prognosis. In this paper, a Capillary Zone Electrophoresis method was developed and validated to determine alpha- and beta-amanitin in urine in less than 7 min using 5 mM, pH 10 borate buffer as background electrolyte. The separation conditions were: capillary: 75 microm I.D., 41 cm effective length, 48 cm total length, 25 degrees C, 20 KV and PDA detection at 214 nm. Sample treatment for analysis only required urine dilution in background electrolyte. The method was validated following established criteria and was found to be selective, linear in the range 5-100 ng/ml. Intra- and inter-day precision and accuracy were within required limits. Limit of detection (LOD) and limit of quantification (LOQ) were 1.5 and 5 ng/ml, respectively. Eight urine samples from suspected cases of intoxication with amanitins were analyzed after 2 years of storage at -20 degrees C, and beta-amanitin was determined in two samples with concentrations of 53 and 65 ng/ml, respectively. The method here described includes the use of non-aggressive reagents to the capillary or the system and is the first Capillary Electrophoresis method used to determine amanitins in clinical samples.