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Multidrug resistant tuberculosis in Sweden
18
Tubercle and Lung Disease: Supplement
pulmonary tuberculosis was made only at autopsy, having positive postmortem cultures.
_ all
The results demonstrate that bactericidal drugs cause a rapid fall in the amount of tubercle bacilli, but tubercle bacilli survive in the lung tissue in many patients longer than the two weeks’ period which has been considered the practical limit of contagiousness. However, infectivity and postmortem culture positivity are different concepts.
61 RAPID DIAGNOSIS OF PULMONARY TB BY THE GEN-PROBE@ AMPLIFIED MYCOBACTERIUM TUBERCULOSIS DIRECT TEST Pfyffer, G. E., Kissling, P., Wirth, R. & Weber, R.*; Swiss National Center of Mycobacteria, Dept. of Medical Microbiology, University of Zurich, 2028 Zurich, and *Div. of Infectious Diseases, Dept. of Internal Medicine, University Hospital, 8091 Zurich, Switzerland.
Gen-Probe has developed the Amplified M. tuberculosis Direct Test (MTD) for the detection of M. tuberculosis complex from respiratory specimens. Prior to hybridization to the acridinium-labeled DNA probe, an enzymemediated step amplifies the target rRNA of the bacteria. The test is easy to perform, does not require costly equipment, and reduces time to detection from weeks to 4-5 hours. In our study, a total of 938 specimens (633 sputa, 249 bronchial and tracheal aspirates, 56 broncho-alveolar lavages) from 589 patients were tested for direct detection of M. tuberculosis complex by the MTD and compared with the conventional methodology of fluorescence microscopy and cultivation (solid and radiometric media). One series (N = 515) was decontaminated with N-acetylL-cysteine (NALC)/NaOH, the other one (N = 423) with sodium dodecyl (lauryl) sulfate (SDS)/NaOH. Overall sensitivity and specificity of the MTD were 92.9 % and 96.2% after NALC decontamination, and 97.2% and 96.1% after SDS treatment. Analysis of the discordant results revealed that quite a few culture negative/MTD positive specimens were considered true positive after having reviewed the patients’ clinical data. Following resolution of the discrepancies 93.9 % sensitivityl97.6 % specificity for the first series (NALC), and 97.4 % sensitivity/96.9% specificity for the second one (SDS) were obtained. The positive predictive value of the MTD was 80.7% (NALC) and 76% (SDS), the negative predictive value was 99.3 % (NALC) and 99.7 % (SDS). As shown by our data the test works slightly though statistically not significantly (P > 0.05) better for SDS decontaminated specimens. In conclusion, MTD offers a new, extremely sensitive technique to rapidly detect M. tuberculosis complex in both smear-positive and smear-negative respiratory specimens.
62 MULTIDRUG RESISTANT TUBERCULOSIS IN SWEDEN Romanas, V., Hoffner, S. E., Kallenius, G. Swedish Instiute for Infectious Disease Control, S-10521 Stockholm, Sweden.
During the last decades the incidence of tuberculosis has steadily decreased in Sweden. However, during recent years the number of new cases has been unchanged, with about 550 new cases per year, and in 1992 the incidence increased to 610, mainly dependent on an increased immigration from countries with a high prevalence of
tuberculosis. We have investigated the incidence of patients with drug resistant tuberculosis presenting during the years 1991 and 1992 in Sweden. In 1991 30 (7.0%) of culture verified tuberculosis cases had isolates that were resistant to one or more of the drugs streptomycin, isoniazid, rifampicin pyrazinamide or ethambutol. In 1992 the corresponding figure was 24 (5.0 %). A majority (38/54) of the patients with resistant TB strains were immigrants. Resistance to the combination isoniazid/rifampicin was demonstrated in 1.2 % of cases in 1991 and 1992. Thus, the incidence of multidrug resistant tuberculosis was low.
63 DNA TYPING OF M. TUBERCULOSIS: EPIDEMIOLOGY AND EVALUATION OF CHEMOTHERAPY IN DEVELOPING COUNTRIES Rigouts, L., Gomez, J. E., Deun, A. V., Collar& .I. P. and Portaels, F.; Institute of Tropical Medicine, Nationalestraai 155, 2000 Antwerpen, Belgium
For the establishement of a data base of DNA types of M. tuberculosis, fingerprints were produced of 335 isolates from Colombia, Rwanda and Burundi. Strain specific fingerprints of PvuIZ restricted chromosomal DNA were generated after hybridisation with a DNA probe of the insertion sequence IS6110. Probe labeling and detection was performed using the enhanced chemiluminescence gene detection system (Amersham International plc). All investigated strains possess 1 to 20 copies of the IS6110. Results show that although about 50% of the strains from the highly endemic countries display countryspecific banding patterns, the fingerprinting data appear to be useful for epidemiological investigations due to small differences, which do exist between virtually all strains from a particular geographic origin. The IS6110 patterns of 38 patients from whom at least twice M. tuberculosis was isolated within a period of 6 months of short drug therapy, were identical for 33 patients indicating unsuccessful therapy at the time of monitoring. From 5 patients strains were isolated which differed in DNA type before and during less than four months of drug therapy. These strains all were drug sensitive, except one relapse strain, which was single resistant to rifampicin. Additional studies are under way to explain these results (reinfection with a new strain, double initial infection or errors during collection or processing the specimens). Fingerprints of drug resistant isolates in Kigali (Rwanda) suggest a nosocomial dissemination of 4 different multi drug resistant strains and of 1 single resistant (rifampicin) strain. These data indicate that clonal dissemination of multi drug resistant strains, as firstly observed in prisons and hospitals in the U. S. A., does occur also in Africa and that new strategies to control this alarming development are urgently needed.
64 &G-TYPE ANTIBODIES AGAINST ANTIGEN A60 OF M. TUBERCULOSIS IN TB AND OTHER LUNG DISEASES Rottoli, P., Olia, P.M., Rosi, P., Trusso, M. *, Vagliasindi, M.; Institute of Respiratory Diseases, University of Siena, Via dei Tufi I, and *Pneumology Unit, USL 30, 53100 Siena, Italy.
Contradictory data exists on the utility of investigating specific antibody response in the study of tuberculosis, due
Tubercle and Lung Disease: Supplement
pulmonary tuberculosis was made only at autopsy, having positive postmortem cultures.
_ all
The results demonstrate that bactericidal drugs cause a rapid fall in the amount of tubercle bacilli, but tubercle bacilli survive in the lung tissue in many patients longer than the two weeks’ period which has been considered the practical limit of contagiousness. However, infectivity and postmortem culture positivity are different concepts.
61 RAPID DIAGNOSIS OF PULMONARY TB BY THE GEN-PROBE@ AMPLIFIED MYCOBACTERIUM TUBERCULOSIS DIRECT TEST Pfyffer, G. E., Kissling, P., Wirth, R. & Weber, R.*; Swiss National Center of Mycobacteria, Dept. of Medical Microbiology, University of Zurich, 2028 Zurich, and *Div. of Infectious Diseases, Dept. of Internal Medicine, University Hospital, 8091 Zurich, Switzerland.
Gen-Probe has developed the Amplified M. tuberculosis Direct Test (MTD) for the detection of M. tuberculosis complex from respiratory specimens. Prior to hybridization to the acridinium-labeled DNA probe, an enzymemediated step amplifies the target rRNA of the bacteria. The test is easy to perform, does not require costly equipment, and reduces time to detection from weeks to 4-5 hours. In our study, a total of 938 specimens (633 sputa, 249 bronchial and tracheal aspirates, 56 broncho-alveolar lavages) from 589 patients were tested for direct detection of M. tuberculosis complex by the MTD and compared with the conventional methodology of fluorescence microscopy and cultivation (solid and radiometric media). One series (N = 515) was decontaminated with N-acetylL-cysteine (NALC)/NaOH, the other one (N = 423) with sodium dodecyl (lauryl) sulfate (SDS)/NaOH. Overall sensitivity and specificity of the MTD were 92.9 % and 96.2% after NALC decontamination, and 97.2% and 96.1% after SDS treatment. Analysis of the discordant results revealed that quite a few culture negative/MTD positive specimens were considered true positive after having reviewed the patients’ clinical data. Following resolution of the discrepancies 93.9 % sensitivityl97.6 % specificity for the first series (NALC), and 97.4 % sensitivity/96.9% specificity for the second one (SDS) were obtained. The positive predictive value of the MTD was 80.7% (NALC) and 76% (SDS), the negative predictive value was 99.3 % (NALC) and 99.7 % (SDS). As shown by our data the test works slightly though statistically not significantly (P > 0.05) better for SDS decontaminated specimens. In conclusion, MTD offers a new, extremely sensitive technique to rapidly detect M. tuberculosis complex in both smear-positive and smear-negative respiratory specimens.
62 MULTIDRUG RESISTANT TUBERCULOSIS IN SWEDEN Romanas, V., Hoffner, S. E., Kallenius, G. Swedish Instiute for Infectious Disease Control, S-10521 Stockholm, Sweden.
During the last decades the incidence of tuberculosis has steadily decreased in Sweden. However, during recent years the number of new cases has been unchanged, with about 550 new cases per year, and in 1992 the incidence increased to 610, mainly dependent on an increased immigration from countries with a high prevalence of
tuberculosis. We have investigated the incidence of patients with drug resistant tuberculosis presenting during the years 1991 and 1992 in Sweden. In 1991 30 (7.0%) of culture verified tuberculosis cases had isolates that were resistant to one or more of the drugs streptomycin, isoniazid, rifampicin pyrazinamide or ethambutol. In 1992 the corresponding figure was 24 (5.0 %). A majority (38/54) of the patients with resistant TB strains were immigrants. Resistance to the combination isoniazid/rifampicin was demonstrated in 1.2 % of cases in 1991 and 1992. Thus, the incidence of multidrug resistant tuberculosis was low.
63 DNA TYPING OF M. TUBERCULOSIS: EPIDEMIOLOGY AND EVALUATION OF CHEMOTHERAPY IN DEVELOPING COUNTRIES Rigouts, L., Gomez, J. E., Deun, A. V., Collar& .I. P. and Portaels, F.; Institute of Tropical Medicine, Nationalestraai 155, 2000 Antwerpen, Belgium
For the establishement of a data base of DNA types of M. tuberculosis, fingerprints were produced of 335 isolates from Colombia, Rwanda and Burundi. Strain specific fingerprints of PvuIZ restricted chromosomal DNA were generated after hybridisation with a DNA probe of the insertion sequence IS6110. Probe labeling and detection was performed using the enhanced chemiluminescence gene detection system (Amersham International plc). All investigated strains possess 1 to 20 copies of the IS6110. Results show that although about 50% of the strains from the highly endemic countries display countryspecific banding patterns, the fingerprinting data appear to be useful for epidemiological investigations due to small differences, which do exist between virtually all strains from a particular geographic origin. The IS6110 patterns of 38 patients from whom at least twice M. tuberculosis was isolated within a period of 6 months of short drug therapy, were identical for 33 patients indicating unsuccessful therapy at the time of monitoring. From 5 patients strains were isolated which differed in DNA type before and during less than four months of drug therapy. These strains all were drug sensitive, except one relapse strain, which was single resistant to rifampicin. Additional studies are under way to explain these results (reinfection with a new strain, double initial infection or errors during collection or processing the specimens). Fingerprints of drug resistant isolates in Kigali (Rwanda) suggest a nosocomial dissemination of 4 different multi drug resistant strains and of 1 single resistant (rifampicin) strain. These data indicate that clonal dissemination of multi drug resistant strains, as firstly observed in prisons and hospitals in the U. S. A., does occur also in Africa and that new strategies to control this alarming development are urgently needed.
64 &G-TYPE ANTIBODIES AGAINST ANTIGEN A60 OF M. TUBERCULOSIS IN TB AND OTHER LUNG DISEASES Rottoli, P., Olia, P.M., Rosi, P., Trusso, M. *, Vagliasindi, M.; Institute of Respiratory Diseases, University of Siena, Via dei Tufi I, and *Pneumology Unit, USL 30, 53100 Siena, Italy.
Contradictory data exists on the utility of investigating specific antibody response in the study of tuberculosis, due