The application of molecular techniques to the diagnosis and epidemiology of mycobacterial diseases

High-throughput epidemiologic typing in clinical microbiology

“…Although it has been convincingly demonstrated that the rate of change of the mycobacterial IS6110 fingerprint is within the theoretical limitations posed by short-term epidemiology [53], mild criticism has recently been made of IS6110 RFLP analysis. Strains with limited numbers of IS6110 were discovered [54], and it was suggested that IS6110-related polymorphism was not random in M. tuberculosis, thereby possibly biasing epidemiologic studies [55]. The latter phenomenon was suggested because of rather extensive band sharing between otherwise unrelated strains, implying that non-significant overlap might confuse the epidemiologic interpretation of the data.…”

Science, medicine, and the future: Tuberculosis

“…After an extensive but disappointing search for a serological test, attention has largely turned to nucleic acid technology, particularly the polymerase chain reaction (PCR) and related techniques 6. In these techniques, the replication of the DNA chain that occurs in dividing cells is induced in vitro by the addition of the requisite enzymes and building blocks (ribonucleotides) and short strands of DNA specific for M tuberculosis (primers).…”

“…The amplification cycle is repeated many times, and in a two hour period just a few DNA chains may be amplified to millions and are thus readily detectable. Use of such tests, some of which are available commercially,6 has met with several problems including cross contamination, lower than expected sensitivity, considerable variation between laboratories in collaborative trials, and false positive results 7. This is a rapidly developing subject, and, while these problems are being addressed, other modifications of the technique such as the ligase chain reaction (LCR) are being tried.…”

“…These fragments are sorted by size on an electrophoretic gel, and the pattern of fragments produced by different strains are compared. It is also possible to do rapid fingerprinting on the DNA products of the polymerase chain reaction 6. There are also prospects for rapid detection of drug resistant strains based on detecting mutations in the genes determining drug susceptibility.…”

Dinâmica espacial do cancro cítrico, interação com a larva minadora dos citros (>i<Phyllocnistis citrella>/i<) e diversidade genética do seu agente causal (>i<Xanthomonas axonopodis PV. citri>/i<)

“…A estabilidade no tempo do perfil obtido por análise de Southern com um IS como sonda deve ser avaliada com cuidado, haja vista que o valor epidemiológico de elementos IS como ferramentas de tipagem se baseia muito neste parâmetro (Pestel-Caron & Arbeit, 1998). Embora IS's sejam elementos móveis, o evento de transposição pode ocorrer em baixas freqüências, e, conseqüentemente, os perfis obtidos serem estáveis durante um prolongado crescimento in vitro e in vivo (Bauer & Andersen, 1999;Butcher et al,1996;Hermans et al, 1991;Rastogi et al, 1992;Van Soolingen et al, 1991). A eficiência discriminatória de um elemento IS varia dependendo de sua habilidade de transposição dentro do genoma com alta ou baixa especificidade de seqüência alvo (Butcher et al, 1996).…”