Multidrug-resistant (MDR) Mycobacterium tuberculosis isolates are resistant to at least isoniazid (INH) and rifampin (RIF), the two most important components of effective antituberculosis therapy. Incorrect use of the drugs, treatment failures, and the transmission of MDR isolates have caused multidrug-resistant tuberculosis (MDR-TB) to become a rapidly increasing health problem in both developed and developing countries (3, 5). Drug susceptibility testing by conventional methods takes several weeks, while early diagnosis of the disease and the rapid identification of resistant strains are essential for efficient treatment and control of the MDR strains.In the last few years, there has been considerable progress in our understanding of the mechanisms of action and of the basis of resistance to the antituberculous drugs, especially resistance to INH and RIF. Resistance to INH has been associated with alterations in at least four genes, but extensive studies have demonstrated that INH resistance is most frequently associated with a specific mutation in codon 315 of M. tuberculosis catalase peroxidase (katG) gene (13). The prevalence of M. tuberculosis katG mutations varies geographically, but the katG codon 315 mutation is found in between 60 and 90% of the INH-resistant strains (1, 2, 4, 9, 10, 15). The mechanism of resistance to RIF involves missense mutations in a well-characterized region of the beta subunit of DNA-dependent RNA polymerase (which is encoded by the rpoB gene). Several studies have shown that more than 95% of RIF-resistant strains harbor a mutation within an 81-bp region of the rpoB gene (8,16,17).Generally, DNA sequencing-based approaches are considered the reference assays for the detection of mutations, but often, they have been found to be too cumbersome for routine use. The commercial strip assay INNO-LiPA Rif. TB (Innogenetics, Ghent, Belgium) has previously been evaluated for the detection of mutations conferring resistance to RIF in M. tuberculosis (7,11,14). The Genotype MTBDR assay (Hain Lifescience GmbH, Nehren, Germany) is a novel kit-based method for the detection of the most common mutations in M. tuberculosis katG and rpoB.The Genotype MTBDR test is based on the same general principle as the INNO-LiPA Rif. TB test, but it has the advantage of being able to detect the presence of mutations in both katG and rpoB simultaneously and thus predict resistance to both INH and RIF (6).Both strip tests are based on reverse hybridization of amplicons (katG in the Genotype MTBDR test and rpoB in both tests) to immobilized, membrane-bound probes covering the wild-type (WT) sequences; the katG 315 mutation (the Genotype MTBDR test); and the rpoB mutations Asp516Val, His526Tyr, His526Asp, and Ser531Leu. The aim of this study was to compare the performances of the Genotype MTBDR test and the INNO-LiPA Rif TB test for the rapid detection of MDR among Finnish and Russian M. tuberculosis isolates. The line probe assay results were compared to the results obtained by conventional sequencing and pheno...

Despite a rapid increase in the number of patients with Lyme neuroborreliosis (LNB), its neuropathological aspects are poorly understood. The objective of this study was evaluation of neuropathological, microbiological, and magnetic resonance imaging (MRI) findings in three patients with the Borrelia burgdorferi infection and neurological disease from whom brain tissue specimens were available. Perivascular or vasculitic lymphocytic inflammation was detected in all specimens. Large areas of demyelination in periventricular white matter were detected histologically and by MRI in one patient. The disease had a fatal outcome in this patient. Brain MRI suggested malignancies in two patients before histopathological studies were carried out. One of these two patients was a child with sudden hemiparesis. Another was a 40-year-old man presenting with epileptic seizures and MRI-detected multifocal lesions, which disappeared after repeated courses of antibiotics. We conclude that cerebral lymphocytic vasculitis and multifocal encephalitis may be associated with B. burgdorferi infection. The presence of B. burgdorferi DNA in tissue samples from areas with inflammatory changes indicates that direct invasion of B. burgdorferi may be the pathogenetic mechanism for focal encephalitis in LNB.

A total of 165 patients with disseminated Lyme borreliosis (diagnosed in 1990-94, all seropositive except one culture-positive patient) were followed after antibiotic treatment, and 32 of them were regarded as having a clinically defined treatment failure. Of the 165 patients, 136 were tested by polymerase chain reaction (PCR) during the follow-up. PCR was positive from the plasma of 14 patients 0-30 months after discontinuation of the treatment, and 12 of these patients had a clinical relapse. In addition, Borrelia burgdorferi was cultured from the blood of three patients during the follow-up. All three patients belonged to the group with relapse, and two of them were also PCR positive. This report focuses on the 13 patients with clinical relapse and culture or PCR positivity. Eight of the patients had culture or PCR-proven initial diagnosis, the diagnosis of the remaining five patients was based on positive serology only. All 13 patients were primarily treated for more than 3 months with intravenous and/or oral antibiotics (11 of them received intravenous ceftriaxone, nine for 2 weeks, one for 3 weeks and one for 7 weeks, followed by oral antibiotics). The treatment caused only temporary relief in the symptoms of the patients. All but one of them had negative PCR results immediately after the first treatment. The patients were retreated usually with intravenous ceftriaxone for 4-6 weeks. None of them was PCR positive after the retreatment. The response to retreatment was considered good in nine patients. We conclude that the treatment of Lyme borreliosis with appropriate antibiotics for even more than 3 months may not always eradicate the spirochete. By using PCR, it is possible to avoid unnecessary retreatment of patients with 'post-Lyme syndrome' and those with 'serological scars' remaining detectable for months or years after infection.

Lyme borreliosis, an infection caused by the tick-borne spirocheteBorrelia burgdorferi, is a major health problem for populations in areas of endemicity in the Northern Hemisphere. In the present study we assessed the density of ticks and the prevalence ofB. burgdorferi sensu lato among ticks in popular urban recreational areas of Helsinki, Finland. Altogether 1,688 Ixodes ricinus ticks were collected from five areas located within 5 km of the downtown section of Helsinki, and 726 of them (303 nymphs, 189 females, and 234 males) were randomly chosen for laboratory analysis. The midguts of the ticks were divided into three pieces, one for dark-field microscopy, one for cultivation in BSK-II medium, and one for PCR analysis. Ticks were found in all the study areas; their densities varied from 1 to 36 per 100 m along which a cloth was dragged. The rate of tick infection with B. burgdorferi sensu lato varied from 19 to 55%, with the average being 32%. Borellia afzelii was the most predominant genospecies in all the areas, and no B. burgdorferi sensu stricto isolates were detected. Only two ticks were concurrently infected with both B. afzelii and Borrelia garinii. Dark-field microscopy gave more positive results for B. burgdorferi than did cultivation or PCR analysis. However, the agreement between all three methods was fairly good. We conclude that Lyme borreliosis can be contracted even in urban environments not populated with large mammals like deer or elk. The disease should be taken into account in the differential diagnosis of certain symptoms of patients from these areas, and the use of measures to improve the awareness of the general population and health care officials of the risk of contracting the disease is warranted.

Altogether, 343 adult and 111 nymphal Ixodes ricinus ticks collected from parks in Turku and suburban and rural islands of the Turku archipelago, Finland, and 100 adult I. ricinus ticks collected from Vormsi Island, Estonia, were included in this study. Using the polymerase chain reaction the ticks were examined for 16S rDNA of the Ehrlichia phagocytophila genogroup and for Borrelia burgdorferi sensu lato recA and flagellin genes. None of the Finnish ticks was found to be infected with E. phagocytophila, whereas 3% of the Estonian ticks were positive for this organism. The rate of Finnish ticks infected with B. burgdorferi sensu lato varied from 0% to 11.6% (mean 5%; 9% for adult and 4% for nymphal ticks). The corresponding rate for Estonian ticks was 15%. Borrelia afzelii was the most common genospecies in both Finnish (2.6%) and Estonian (12%) ticks. B. burgdorferi sensu stricto was detected in 2.0% of the Finnish ticks, but in none of the Estonian ticks. These results suggest that the E. phagocytophila genogroup is very rare in Finnish ticks, although the ticks were collected from an area endemic for Lyme borreliosis. In Estonia, E. phagocytophila is found in ticks and may cause disease.