Implementation of a molecular typing system to support epidemiological investigations in the tuberculosis health care system in Vienna.

Tuberculosis continues to be one of the predominant infectious diseases. Effective control of its spread requires that sources of infection and routes of transmission be disclosed as quickly as possible. At present such investigations are still performed by conventional epidemiological methods. In the recent past, however, molecular typing systems were added to the spectrum of epidemiological tools. Unfortunately, they were applied to retrospective investigations rather than used as an aid in the health care system. In this study, 515 Mycobacterium tuberculosis strains isolated during 1997 and 1998 in Vienna were analysed by spoligotyping, a molecular technique requiring no further cultivation of mycobacteria. The study was aimed to assess the suitability of the method as a quick means of disclosing new cases. Thus, clusters obtained by spoligotyping were analysed along with demographic and epidemiological data and compared with clusters obtained by conventional epidemiological techniques alone. In addition, spoligotype-forming clusters were matched with an international database containing spoligotypes from four different studies. Of 515 isolates, 107 showed an unique pattern. The remaining 408 isolates were distributed into two large clusters of 82 and 73 isolates and into 49 smaller ones consisting of 2 to 33 isolates each. The two spoligotypes forming the large clusters were identical with the most prevalent spoligotypes in the world. Therefore, for the tuberculosis authorities, information was only gained by excluding rather than tracing possible ways of transmission. Twenty-two of the 49 spoligotypes forming smaller clusters were identical with strains found in other parts of the world. Seventeen of 22 infection chains assumed by conventional investigations were confirmed by spoligotyping. In small clusters, an additional 24 infections were assumed due to similarities such as living conditions or socioeconomic status. In 27 clusters, all patients sharing the same strain belong to the same country or geographical area. In conclusion, spoligotyping proved suitable as an early guide in conventional investigations to trace routes of M. tuberculosis transmission in a community. However, when a strain isolated from a patient belongs to a spoligotype shared by many isolates, a second molecular typing method is required.

Two enzyme immunoassays and PCR for detection of Helicobacter pylori in stool specimens from pediatric patients before and after eradication therapy.

This study of pediatric patients was intended to determine the suitability of stool PCR and two antigen enzyme immunoassays (EIAs; Premier Platinum HpSA and the novel FemtoLab H. pylori), which detect Helicobacter pylori antigens in feces, as pretreatment diagnostic tools and especially as posttreatment control. Forty-nine H. pylori-infected children with dyspepsia received eradication therapy. Successful treatment was determined by a negative [(13)C]urea breath test 4 and 12 weeks after discontinuation of therapy. Fecal specimens were collected prior to eradication therapy as well as 4 weeks after the end of treatment. Successfully treated children delivered stool samples at 6, 8, and 12 weeks posttreatment also. Specimens were examined by seminested PCR and Premier Platinum HpSA and were reexamined by both EIAs as soon as FemtoLab H. pylori was available. In the first test series, the overall sensitivities of PCR and Premier Platinum HpSA were 93.0 and 91.1%, respectively. With specimens collected at 4 weeks after treatment, the respective specificities were 68.8 and 79.3%. After longer follow-up periods, however, they gradually increased to 100 and 96.9%, respectively. In the new test series, Premier Platinum HpSA delivered a considerably lower number of false-positive results (4 versus 18), indicating intertest variations. The overall test sensitivity was 94.6%, and the overall specificity was 97.5%. FemtoLab H. pylori showed an excellent performance with an overall sensitivity and specificity of 98.2 and 98.1%, respectively. Thus, in contrast to PCR, both EIAs were shown to be suitable for early posttreatment control.

Drug resistance rates of Mycobacterium tuberculosis strains in Austria between 1995 and 1998 and molecular typing of multidrug-resistant isolates. The Austrian Drug Resistant Tuberculosis Study Group.

In this study the drug resistance pattern of 3559 Mycobacterium tuberculosis strains isolated in Austria between 1995 and 98 was evaluated. Of these strains, 165 (4.6%) were resistant to one or more drugs, 113 (3.2%) to one of the tested drugs and 53 (1.5%) to two or more drugs. Monodrug resistance was observed most often to isoniazid (56 strains), followed by streptomycin (44 strains). Resistance to rifampicin or ethambutol alone was rarely seen (12 strains and 1 strain, respectively). Of the 53 strains resistant to 2 or more drugs, 25 were resistant to isoniazid and streptomycin, while 17 were multidrug resistant. Molecular typing revealed a large diversity among the multidrug-resistant strains.