An allele-specific amplification method based on two genetic polymorphisms to differentiate Mycobacterium tuberculosisfrom Mycobacterium bovis was tested. Based on the differences found at position 169 in the pncA genes fromM. tuberculosis and M. bovis, a PCR system which was able to differentiate most of the 237 M. tuberculosis complex isolates tested in one of the two species was developed. All 121 M. tuberculosis strains showed the expected base (cytosine) at position 169. Most of the M. bovis isolates had a guanine at the cited position. Nevertheless, 18 of the 116 M. bovis isolates, all of them goat isolates, showed the pncA polymorphism specific to M. tuberculosis. These results suggest that goat M. bovis may be the nicotinamidase-missing link at the origin of theM. tuberculosis species. Based on the polymorphism found at position 285 in the oxyR gene, the same system was used to differentiate M. tuberculosis from M. bovis. In this case, DNAs from all 121 M. tuberculosis isolates had the expected base (guanine) at this position. In addition, all 116M. bovis isolates, including those from goats, showed the identical polymorphism (adenine). The oxyR allele-specific amplification method can differentiate M. bovis fromM. tuberculosis, is rapid (results can be obtained in less than 3 h), and is easy to perform.

The Global Meningococcal Initiative (GMI) is an international group of scientists and clinicians with expertise in meningococcal disease (MD). It promotes MD prevention through education and research. Given geographic differences in disease epidemiology, prevention strategies (e.g., vaccination) should be country-specific to ensure local needs are met. However, regional policies/recommendations and standardized disease diagnostic criteria should be implemented to improve surveillance and control strategies, and allow for more robust data comparisons. Consequently, the GMI convened a meeting with Latin American representatives to discuss the burden of MD and vaccination practices/policies, and consider if the global GMI recommendations could be tailored. The group determined that as robust, uniform epidemiologic data are required to make informed health-policy decisions, it would be useful to first summarize the regional situation herein (including disease surveillance, case definitions, epidemiology, vaccination and outbreak control strategies) and then determine a consensus-based meningococcal case definition for use throughout the region.

Nineteen multidrug-resistant (MDR) Mycobacterium complex strains isolated in a nosocomial outbreak were characterized at the molecular level. The strains were microbiologically characterized as Mycobacterium bovis. The mpt40 sequence was not present in chromosomal DNA from these strains, supporting the fact that they were M. bovis. All of the isolates were resistant to isoniazid, rifampin, pyrazinamide, ethambutol, streptomycin, para-aminosalicylic acid, clarithromycin, cycloserine, ethionamide, ofloxacin, capreomycin, and amikacin. By performing the standardized IS6110 fingerprinting by restriction fragment length polymorphism (RFLP) analysis, we were able to differentiate two groups (groups A and B) containing two (16 isolates) and three (3 isolates) IS6110 copies, respectively. These strains were typed by spoligotyping, developed to distinguish M. bovis strains and also to distinguish them from M. tuberculosis strains (J. Kamerbeek et al., J. Clin. Microbiol. 35:907-914, 1997). All the strains were confirmed to be M. bovis. In addition, spoligotyping showed a difference in only 1 of 43 spacers between RFLP groups A and B. The rpo␤ region of several strains representative of each identified group was cloned and sequenced, and identical mutations (Ser-531 to Leu) responsible for the rifampin resistance phenotype were found. To our knowledge, this is the first characterization at the molecular level of an MDR M. bovis strain responsible for a nosocomial outbreak.

Prevalence of Neisseria meningitidis carriers in children under five years of age and teenagers in certain populations of Mexico City.

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