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Category: Fungi and Fungal Pathogenesis; Clinical Microbiology
Molecular Epidemiology of Tuberculosis, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555818357/9781555819101_Chap33-1.gif /docserver/preview/fulltext/10.1128/9781555818357/9781555819101_Chap33-2.gifAbstract:
Molecular epidemiology is the integration of molecular techniques to track specific strains of pathogens with conventional epidemiologic approaches to understanding the distribution of disease in populations. This chapter describes the genetic elements of Mycobacterium tuberculosis that may be exploited as strain-specific markers, the strain-typing methods that are based on these elements, and some of the DNA fingerprinting results obtained to date and speculates on future directions in this field. M. tuberculosis complex bacteria constitute a remarkably homogeneous group, as revealed by the inability of multilocus enzyme electrophoresis to differentiate individual strains and the minimal DNA polymorphism in restriction fragments of randomly chosen chromosomal DNA fragments. Most investigators use the technique of Southern blotting to exploit the presence of the above-described genetic elements to reveal restriction fragment length polymorphisms (RFLP) among M. tuberculosis strains. The application of molecular techniques in this setting suggests that tuberculosis control efforts should be focused on this population to prevent the emergence and spread of multidrug-resistant (MDR) tuberculosis in Europe. Differences in the genetic stabilities of such genetic elements can be used to exploit these elements as molecular clocks in the evolution of divergent strains. A major future challenge of DNA fingerprinting of M. tuberculosis will be to determine the paces of change of the various elements and to match these to study specific epidemiologic questions.
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IS6110-based DNA fingerprinting results of initial (lanes A) and subsequent (lanes B) isolates of M. tuberculosis from patients with tuberculosis isolated from serial sputum samples. In each patient, the time interval between samples was 7 to 29 months, and subsequent isolates demonstrated increasing antimicrobial resistance. Serial RFLP patterns either are identical or differ by one additional band (arrow). The last two lanes contain negative and positive control DNA. (Reprinted by permission of the New England Journal of Medicine [ Small et al., 1993b ].)
IS6110-based DNA fingerprinting results of initial (lanes A) and subsequent (lanes B) isolates of M. tuberculosis from patients with tuberculosis isolated from serial sputum samples. In each patient, the time interval between samples was 7 to 29 months, and subsequent isolates demonstrated increasing antimicrobial resistance. Serial RFLP patterns either are identical or differ by one additional band (arrow). The last two lanes contain negative and positive control DNA. (Reprinted by permission of the New England Journal of Medicine [ Small et al., 1993b ].)
Insertion sequences and repetitive DNA in M. tuberculosis
Insertion sequences and repetitive DNA in M. tuberculosis