The first occurrence of a multi-drug resistant tuberculosis epidemic in the Czech Republic caused by genetically closely related Mycobacterium tuberculosis strains.

DNA fingerprinting based on the detection of the insertion sequence IS6110 in Pvull restriction fragments was applied to M. tuberculosis isolates originating in the first microepidemic of multidrug resistant tuberculosis recorded in the Czech Republic. Their disseminators were 21 individuals living in--or roaming between three distant areas. The age of 17 males ranged from 36 to 64 years (average 45 years) and of 4 females aged from 38 to 52 years. The index person was most probably a former male prisoner, aged 49 years, who disseminated multidrug resistant M. tuberculosis over a period of 28 months. In ten of the patients the following risk factors for tuberculosis were found: imprisonment, homelessness, immigration and previous stay in asylum--or in a psychiatric ward. In six cases, M. kansasii infection preceded tuberculosis. Four out of the 21 patients died. The RFLP analysis separated the patients into two distinct groups: group A comprising 14 members of which M. tuberculosis strains were isolated with six IS6110 copies, whereas the isolates of seven individuals of the group B, the RFLP profile displayed highly similar RFLP patterns compared to the isolates of group A, but with two additional IS6110 copies. In one patient, both A and B patterns were found: the first one in a M. tuberculosis strain isolated in 1993 and the second one in the isolate isolated two years later. Both the appearance of pattern B among the isolates of a part of patients and the switch from A to B pattern in one of patients can be plausibly explained by the unstability of DNA genotypes caused by transposition of IS6110 elements.

A multidrug-resistant tuberculosis microepidemic caused by genetically closely related Mycobacterium tuberculosis strains.

IS6110 DNA fingerprinting was used to characterize an outbreak of multidrug-resistant tuberculosis in 21 individuals (17 males and 4 females) living in or roaming among four distantly separated areas in the Czech Republic. The restriction fragment length polymorphism (RFLP) analysis separated the collected Mycobacterium tuberculosis strains into group A, including 14 patients with six IS6110 copies, and group B, with 7 patients displaying highly similar RFLP patterns but with two additional IS6110 bands. A switch from pattern A to pattern B was observed in one patient, and the subsequent detection of subclone B in seven more individuals has been explained by the instability of DNA genotypes caused by transposition of IS6110 elements.

[A micro-epidemic of tuberculosis in the South Moravia Region]. / Mikroepidemie tuberkulózy v Jihomoravském kraji.

In the South Moravian region which is the area with the lowest prevalence of bacillary tuberculosis in the Czech Republic (6.6 per 100,000 population in 1996) in 1993-1996 a total of six local and family microepidemics of tuberculosis were detected. For their identification the RFLP fingerprinting method was used based on evidence of repeated sequence of IS6110 in the chromosomal DNA of the examined strains of Mycobacterium tuberculosis predigested with restrictive enzyme PvuII. The profiles of fingerprints of each microepidemic were included by means of a computer programme into the hierarchy of the fingerprint dendrogram of 184 strains of M. tuberculosis which made it possible to identify possible identical profiles of strains from patients from remote places in the Czech Republic. In three family microepidemics involving always two members no identical fingerprint profiles of other Czech strains of M. tuberculosis were revealed. To the fourth cluster formed by six members of one family an identical RFLP profile of a female patient living in a nearby locality was added. In another microepidemic recorded in three brothers identical fingerprints were found another four patients from the South Moravian region and in one from the Central Bohemian region. The last cluster of two brothers was surprisingly enlarged by six identical RFLP profiles of patients from the West Bohemian region and one from Prague. These findings suggest that in areas with a low prevalence tuberculosis persists more frequently than in areas with a high prevalence as familial or local microepidemics.

[Molecuar epidemiology of tuberculosis]. / Molekulární epidemiologie tuberkulózy.

Tuberculosis is a serious disease, killing many people every year. After decades of progressive decrease this disease, boosted by the appearance of HIV, reemerges showing a marked upward tendency and most afflicting populations in developing countries. At present, many researchers have been involved in molecular epidemiology of tuberculosis using DNA fingerprinting to determine restriction profiles of different strains. This method has also proved useful in detecting outbreaks of the disease in populations. That is very important for determining primary infection sources and their subsequent elimination from the environment to prevent recurrent infections.