Paediatric tuberculosis during universal and selective Bacillus Calmette-Guérin vaccination policy: a nationwide population-based retrospective study, Finland, 1995-2015.

IntroductionIn 2006, the Bacillus Calmette-Guérin (BCG) vaccination policy in Finland changed from universal to selective.AimWe assessed the impact of the policy change on tuberculosis (TB) morbidity in children under 5 years and epidemiological trends of paediatric TB in Finland.MethodsWe conducted a nationwide, population-based, retrospective registry study of all newly diagnosed active TB cases younger than 15 years in Finland from 1995 to 2015 by linking data from the National Infectious Diseases Register, Finnish Care Register for Health Care, medical patient records and Finnish Population Information System. We compared the TB incidence rate ratio of under 5 year-olds with universal and selective BCG vaccinations with a Poisson log-linear model and analysed incidence trends among those younger than 15 years with a negative binomial model.ResultsWe identified 139 paediatric TB cases: 50 native (including 24 second-generation migrants) and 89 foreign-born children. The TB rate of under 5 year-olds remained stable after changing to selective BCG vaccination (incidence rate ratio (IRR): 1.3; 95% confidence interval (CI): 0.7-2.3). TB rate in the native population under 15 years increased slightly (IRR = 1.06; 95% CI: 1.01-1.11).DiscussionPaediatric TB cases in Finland were concentrated in families with migrant background from high-TB incidence countries. The native TB morbidity in under 5-year-olds did not increase after the BCG policy revision, suggesting that selective vaccinations can prevent TB in the most vulnerable age group in low-incidence settings. Second-generation migrants under 15 years in Finland with high TB risk are probably increasing.

Risk factors affecting treatment outcomes for pulmonary tuberculosis in Finland 2007-2014: a national cohort study.

BACKGROUND: Major transition in tuberculosis (TB) epidemiology is taking place in many European countries including Finland. Monitoring treatment outcome of TB cases is important for identifying gaps in the national TB control program, in order to strengthen the system. The aim of the study was to identify potential risk factors for non-successful TB treatment outcomes, with a particular focus on the impact of comorbidities. We also evaluated the treatment outcome monitoring system. METHODS: All notified microbiologically confirmed pulmonary TB cases in Finland in 2007-2014 were included, except multi-drug resistant (MDR) cases. Nationwide register data were retrieved from: Infectious Diseases Register, Population Register, Cause of Death Register and Hospital Discharge Register. Non-successful outcomes were divided into three groups: death, unsatisfactory outcomes and non-defined outcomes. Logistic regression analyses were used to identify risk factors for non-successful outcomes. RESULTS: Treatment outcomes were notified for 98.6% of study cases (n = 1396/1416). Treatment success rate was 75%. The main reason for non-successful outcome was death (16%), whereas outcomes failed and lost to follow-up were rare (1% together). In a multivariable model, risk factors for death as outcome were increasing age, male gender and Charlson comorbidity index ≥1, for unsatisfactory outcomes non-MDR drug resistance and TB registered in the first study period, and for non-defined outcomes non-MDR drug resistance. Among 50 cases with unsatisfactory outcomes, we observed false outcome allocations in eight (16%), and > 2% of the cases transferred to another country or disappeared before or during treatment. CONCLUSIONS: With a high proportion of older population among tuberculosis cases, death is a common treatment outcome in Finland. Comorbidity is an important factor to be incorporated when interpreting and comparing outcome rates. There was a considerable inconsistency in outcome allocation in the monitoring system, which implies that there is need to review the guidelines and provide further training for outcome assessment.

Tuberculosis screening of asylum seekers in Finland, 2015-2016.

BACKGROUND: In Finland, asylum seekers from countries with high tuberculosis (TB) incidence (> 50/100,000 population/year) and those coming from a refugee camp or conflict area are eligible for TB screening. The aim of this study was to characterise the TB cases diagnosed during screening and estimate the yield of TB screening at the reception centres among asylum seekers, who arrived in Finland during 2015-2016. METHODS: Voluntary screening conducted at reception centres included an interview and a chest X-ray. Data on TB screening and health status of asylum seekers was obtained from the reception centres' national health register (HRS). To identify confirmed TB cases, the National Infectious Disease Register (NIDR) data of foreign-born cases during 2015-2016 were linked with HRS data. TB screening yield was defined as the percentage of TB cases identified among screened asylum seekers, stratified by country of origin. RESULTS: During 2015-2016, a total of 38,134 asylum applications were received (57% were from Iraq, 16% from Afghanistan and 6% from Somalia) and 25,048 chest x-rays were performed. A total of 96 TB cases were reported to the NIDR among asylum seekers in 2015-2016; 94 (98%) of them had been screened. Screening identified 48 (50%) cases: 83% were male, 56% aged 18-34 years, 42% from Somalia, 27% from Afghanistan and 13% from Iraq. Furthermore, 92% had pulmonary TB, 61% were culture-confirmed and 44% asymptomatic. TB screening yield was 0.19% (48/25048) (95%CI, 0.14-0.25%) and it varied between 0 and 0.83% stratified by country of origin. Number needed to screen was 522. CONCLUSIONS: TB screening yield was higher as compared with data reported from other European countries conducting active screening among asylum seekers. Half of the TB cases among asylum seekers were first suspected in screening; 44% were asymptomatic. TB yield varied widely between asylum seekers from different geographic areas.

Epidemiology and outcome of HIV patients in Finland co-infected with tuberculosis 1998-2015.

BACKGROUND: Tuberculosis (TB) is a major cause of death in HIV patients worldwide. Here we describe the epidemiology and outcome of HIV-TB co-infections in a high-income country with low TB incidence and integrated HIV and TB therapy according to European guidelines. METHODS: This study was based on the HIV cohort of the Helsinki University Hospital which includes all HIV patients in the Helsinki region with a population of 1.5 million. Totally, 1939 HIV-positives who have been under follow-up between 1998 and 2015 were included. RESULTS: TB was diagnosed in 53 (2.7%) of the HIV-patients. The TB incidence rate was higher in injecting drug users (IRR 3.15; 95% CI 1.33-7.52) and heterosexuals (IRR 3.46; 95% CI 1.64-7.29) compared to men having sex with men. The incidence rate was also higher in those born in Sub-Saharan Africa (IRR 3.53; 95% CI 1.78-7.03) compared to those born in Finland. There was a significant reduction in the total TB incidence rate of 59% per 6-year period between 1998 and 2015 (p < 0.001). In injecting drug users there was a reduction in incidence rate from 1182 to 88 per 100,000 (p < 0.001) and in people born in Sub-Saharan Africa from 2017 to 195 per 100,000 (p < 0.001). Among the 53 HIV-TB co-infected cases, one female and 15 males died during follow up. HIV was the primary cause of death in five patients but none of the deaths were caused by TB. CONCLUSION: The incidence rate of tuberculosis among HIV-positives in Finland has been declining between 1998 and 2015. Among injecting drug users, the reduction is probably explained by harm reduction interventions and care in comprehensive care centers in Helsinki. The increased coverage of antiretroviral therapy is probably another main reason for the decline in TB incidence rates. Despite good treatment results for both HIV and TB, the all-cause mortality among Finnish males with HIV-TB was high, and common causes of death were intoxications and suicides.

Tuberculosis knowledge, attitudes and practices: a cross-sectional study in the Somali population living in Finland.

BACKGROUND: In Finland, the epidemiology of tuberculosis is changing: incidence declined from 13/100 000 in 1995 to 4 in 2016 and the proportion of foreign-borns among all TB cases increased from 5% to 50%. The most common country of origin among foreign-born TB patients was Somalia. Knowledge, attitudes and practices (KAP) studies are used to collect information for planning and tailoring health care services. KAP studies in Finland have been used for other diseases but not to study Somalis in regards to TB. METHODS: The KAP were assessed by a piloted questionnaire. Convenience sampling was performed, and the questionnaire was administered in mosques, shops and Islamic events. Knowledge and attitudes were assessed by creating composite scores. Associations between sociodemographic characteristics and knowledge and attitudes were investigated using logistic regression to compute odds ratios (OR) and 95% confidence intervals (CI). RESULTS: A total of 407 participants took part; 49% were male. Low level of knowledge was held by 53% of participants, and favourable attitude regarding TB by 63%. Knowledge was not associated with gender or country of birth. Female participants were twice more likely to have a favourable attitude than males (adjusted OR, 2.37; 95%CI, 1.40-4.01). Those with high knowledge are twice more likely to have a favourable attitude towards TB (adjusted OR, 2.21; 95%CI, 1.32-3.69). CONCLUSIONS: The population held a favourable attitude towards TB, but knowledge gaps and misconceptions regarding TB were found. The results of this study can be used for designing health communication and targeted preventive measures for the Somali population.

Increase in Childhood Nontuberculous Mycobacterial Infections After Bacille Calmette-Guérin Coverage Drop: A Nationwide, Population-Based Retrospective Study, Finland, 1995-2016.

Background: Epidemiological data on childhood nontuberculous mycobacterial (NTM) disease is scarce and the protective effect of bacille Calmette-Guérin (BCG) vaccination remains debated. In 2006, the BCG policy in Finland changed from universal to selective. We aimed to study the effect of the BCG coverage decrease on the incidence of childhood NTM infections in Finland. Methods: We conducted a nationwide, population-based, retrospective study of NTM notifications recorded to the National Infectious Diseases Register between 1995 and 2016 and identified native-born children aged 0-4 years infected with NTM. Poisson log-linear model was used to estimate the change in the incidence rate of cohorts born during universal or selective BCG policy between 1995 and 2015. Results: We identified 97 native-born children aged <5 years infected with NTM (median age, 27 months; female-to-male ratio, 2:1). The most common species was Mycobacterium avium (n = 69 [71%]). The estimated incidence rates of NTM in universal-BCG and selective-BCG cohorts were 0.2 and 3.9 per 100000 person-years, respectively. The incidence rate ratio of selective-BCG cohorts compared to universal-BCG cohorts was 19.03 (95% confidence interval, 8.82-41.07; P < .001). Conclusions: After infant BCG coverage in Finland decreased, childhood NTM infections increased drastically. As there is no other apparent cause for the increase, this indicates that BCG offers protection against childhood NTM disease. This observation adds to the understanding of childhood NTM epidemiology and might explain why the disease is emerging in some countries.

Enhanced surveillance for tuberculosis among foreign-born persons, Finland, 2014-2016.

BACKGROUND: Tuberculosis (TB) in foreign-born residents is increasing in many European countries including Finland. We conducted enhanced TB surveillance to collect supplementary information on TB cases among recent immigrants and their children to provide data for revising TB control policies in Finland to take into account the decrease in native cases and increase in foreign-born cases. METHODS: TB cases were identified from the National Infectious Diseases Register. Data on foreign-born (if not available, most recent nationality other than Finnish) TB cases notified during 2014-2016 (country of birth, date of arrival to Finland, participation in TB screening, date of first symptoms, and details of possible contact tracing) were requested from physicians responsible for regional communicable disease control through a web-based questionnaire. RESULTS: Questionnaires were returned for 203 (65%) of 314 foreign-born TB cases; 36 (18%) were paediatric cases TB was detected in arrival screening in 42 (21%) and during contact tracing of another TB case in 18 (9%); 143 (70%) cases sought care for symptoms or were identified by chance (e.g. chest x-ray because of an accident). Of cases with data available, 48 (24%) cases were diagnosed within 3 months of arrival to Finland, 55 (27%) cases between 3 months and 2 years from arrival, and 84 (42%) cases after 2 years from arrival. Of all the foreign-born cases, 17% had been in a reception centre in Finland and 15% had been in a refugee camp abroad. CONCLUSIONS: In addition to asylum seekers and refugees, TB screening should be considered for immigrants arriving from high TB incidence countries, since the majority of TB cases were detected among persons who immigrated to Finland due to other reasons, presumably work or study. Further evaluation of the target group and timing of TB screening is warranted to update national screening guidance.

Recurrent tuberculosis in Finland 1995-2013: a clinical and epidemiological cohort study.

BACKGROUND: We investigated the epidemiology and prevalence of potential risk factors of tuberculosis (TB) recurrence in a population-based registry cohort of 8084 TB cases between 1995 and 2013. METHODS: An episode of recurrent TB was defined as a case re-registered in the National Infectious Disease Register at least 360 days from the date of the initial registration. A regression model was used to estimate risk factors for recurrence in the national cohort. To describe the presence of known risk factors for recurrence, patient records of the recurrent cases were reviewed for TB diagnosis confirmation, potential factors affecting the risk of recurrence, the treatment regimens given and the outcomes of the TB episodes preceding the recurrence. RESULTS: TB registry data included 84 patients, for whom more than 1 TB episode had been registered. After a careful clinical review, 50 recurrent TB cases (0.6%) were identified. The overall incidence of recurrence was 113 cases per 100,000 person-years over a median follow up of 6.1 years. For the first 2 years, the incidence of recurrence was over 200/100000. In multivariate analysis of the national cohort, younger age remained an independent risk factor at all time points, and male gender and pulmonary TB at 18 years of follow-up. Among the 50 recurrent cases, 35 patients (70%) had received adequate treatment for the first episode; in 12 cases (24%) the treating physician and in two cases (4%) the patient had discontinued treatment prematurely. In one case (2%) the treatment outcome could not be assessed. CONCLUSIONS: In Finland, the rate of recurrent TB was low despite no systematic directly observed therapy. The first 2 years after a TB episode had the highest risk for recurrence. Among the recurrent cases, the observed premature discontinuation of treatment in the first episode in nearly one fourth of the recurrent cases calls for improved training of the physicians.

[Recognize tuberculosis--prevent outbreak]. / Tunnista tuberkuloosi--ehkäise epidemia.

INTRODUCTION: The number of tuberculosis cases in Finland has decreased. Cases among immigrants have, however, increased, and the disease may not be recognized early enough. METHODS: We describe four group exposures to tuberculosis that occurred in Finland, the index patient coming from a country with a high incidence rate of tuberculosis. RESULTS: Over 900 persons were exposed to tuberculosis. Coordination of the surveys was hampered by the fact that several healthcare operators participated in the study. Three index patients had drug-resistant tuberculosis, one of which was multidrug resistant. CONCLUSIONS: Extensive operations of tracking and prevention could have been avoided, if the symptoms would have been recognized earlier.

Inventory study of non-tuberculous mycobacteria in the European Union.

BACKGROUND: Since non-tuberculous mycobacteria (NTM) disease is not notifiable in most European Union (EU) and European Economic Area (EEA) countries, the epidemiological situation of the >150 NTM species is largely unknown. We aimed to collect data on the frequency of NTM detection and NTM species types in EU/EEA countries. METHODS: Officially nominated national tuberculosis reference laboratories of all EU/EEA countries were asked to provide information on: laboratory routines for detection and identification of NTM, including drug sensitivity testing (DST) methods; data on the number and type of NTM species identified; coverage and completeness of the provided data on NTM; type and number of human specimens tested for NTM; and number of specimens tested for Mycobacterium tuberculosis complex and NTM. This information was summarized and the main results are described. RESULTS: In total, 99 different NTM species were identified with M. avium, M. gordonae, M. xenopi , M. intracellulare, and M. fortuitum identified most frequently. Seven percent of the NTM species could not be identified. NTM was cultured from between 0.4-2.0% of the specimens (data from four countries). The laboratories use culturing methods optimised for M. tuberculosis complex. Identification is mainly carried out by a commercial line probe assay supplemented with sequencing. Most laboratories carried out DST for rapid growers and only at the explicit clinical request for slow growers. CONCLUSION: It is likely that the prevalence of NTM is underestimated because diagnostic procedures are not optimized specifically for NTM and isolates may not be referred to the national reference laboratory for identification. Due to the diagnostic challenges and the need to establish the clinical relevance of NTM, we recommend that countries should concentrate detection and identification in only few laboratories.

[MDR tuberculosis]. / Monilääkeresistentti tuberkuloosi.

The causative agent of MDR tuberculosis is resistant to at least isoniazid and rifampin, and in the case of XDR tuberculosis, also to fluoroquinolones and aminoglycoside. In 2012, 450000 people had MDR tuberculosis and 170000 people died of it. The majority of the cases were reported in South Africa, India, and Russia. In North West Russia nearly one third of the new tuberculosis cases are MDR. In Finland 2-5 new cases of MDR tuberculosis are notified annually, and this far only one case of XDR tuberculosis has been reported. Treatment of MDR tuberculosis lasts longer and costs more than treatment of drug-susceptible tuberculosis. Moreover, the second line drugs used are less effective and have more side effects than the first line drugs.

Transmission of drug-resistant Mycobacterium tuberculosis isolates between Finnish- and foreign-born cases, 2014-2021: A molecular epidemiological study.

BACKGROUND: Data on the molecular epidemiology and transmission of drug-resistant Mycobacterium tuberculosis (MTB) in low-incidence settings with immigration from high-incidence settings is limited. METHOD: We included 115 drug-resistant (DR) MTB isolates with whole-genome sequencing data isolated in Finland between 2014 and 2021. Potential transmission clusters were identified using a threshold of 12 single-nucleotide polymorphisms (SNPs). Highly related clusters were identified using a threshold of 5 SNPs. RESULT: Of the 115 DR MTB isolates, 31 (27.0%) isolates were from Finnish-born cases and 84 (73.0%) were from foreign-born cases. The proportion of multidrug-resistant (MDR) MTB isolates (30/84, 35.7%) from foreign-born cases was higher than that of MDR MTB isolates from Finnish-born cases (8/31, 25.8%). Lineage 2 (40/115, 34.8%) and lineage 4 (40/115, 34.8%) were the most prevalent lineages. A total of 25 (21.7%) isolates were classified into eight potential transmission clusters (≤12 SNPs). Furthermore, five highly related clusters (≤5 SNPs) were identified, including three DR MTB isolates from Finnish-born cases and 14 DR isolates from foreign-born cases. CONCLUSION: The risk of DR MTB transmission between Finnish- and foreign-born persons is not negligible. Further research on clustering analysis in drug-susceptible MTB is worth to inform tuberculosis management and control in low-incidence settings with increasing immigration.

Molecular epidemiology of HIV-associated tuberculosis in Dar es Salaam, Tanzania: strain predominance, clustering, and polyclonal disease.

Molecular typing of Mycobacterium tuberculosis can be used to elucidate the epidemiology of tuberculosis, including the rates of clustering, the frequency of polyclonal disease, and the distribution of genotypic families. We performed IS6110 typing and spoligotyping on M. tuberculosis strains isolated from HIV-infected subjects at baseline or during follow-up in the DarDar Trial in Tanzania and on selected community isolates. Clustering occurred in 203 (74%) of 275 subjects: 124 (80%) of 155 HIV-infected subjects with baseline isolates, 56 (69%) of 81 HIV-infected subjects with endpoint isolates, and 23 (59%) of 39 community controls. Overall, 113 (41%) subjects had an isolate representing the East Indian "GD" family. The rate of clustering was similar among vaccine and placebo recipients and among subjects with or without cellular immune responses to mycobacterial antigens. Polyclonal disease was detected in 6 (43%) of 14 patients with multiple specimens typed. Most cases of HIV-associated tuberculosis among subjects from this study in Dar es Salaam resulted from recently acquired infection. Polyclonal infection was detected and isolates representing the East Indian GD strain family were the most common.

Multidrug-resistant tuberculosis in Finland: treatment outcome and the role of whole-genome sequencing.

Treatment of multidrug-resistant tuberculosis (MDR-TB) is a global challenge requiring long treatment with costly drugs. We assessed treatment combinations, outcome and the utility of whole-genome sequencing (WGS) in MDR-TB cases. Clinical, demographic and microbiological data were obtained of all patients with MDR-TB who started treatment in Finland in 2007-2016. Definitions of MDR, pre-extensively drug-resistant (pre-XDR) and XDR tuberculosis were those applicable at the study period. Treatment outcome was defined according to World Health Organization (WHO) guidelines. Mycobacterium tuberculosis isolates were analysed by WGS in addition to routinely performed phenotypic drug susceptibility testing and genotyping. Among the 47 cases, 35 (74%) had a successful treatment outcome. Risk factors for non-successful outcome were Finnish origin and XDR. Almost 90% of our cases had an adverse event for at least one drug. Phenotypic and WGS drug resistance results were fully concordant for isoniazid, fluoroquinolones and amikacin, and >90% concordant for rifampicin, pyrazinamide, kanamycin and capreomycin. >60% of phenotypically ethambutol-susceptible isolates were genotypically resistant. The results of the rifampicin and isoniazid nucleic acid amplification tests (NAATs) performed for the isolates were identical to the WGS results except for three isolates having uncommon resistance mutations not included in the NAATs. WGS did not reveal unexpected clustering. More training is needed for physicians treating MDR-TB, and especially XDR-TB, to improve treatment outcome. Phenotypic drug susceptibility testing was shown to be unreliable for ethambutol. WGS could aid in the selection of optimal treatment regimen in the future.

Transmission of tuberculosis between foreign-born and Finnish-born populations in Finland, 2014-2017.

We describe the epidemiology of tuberculosis (TB) and characterized Mycobacterium tuberculosis (M. tuberculosis) isolates to evaluate transmission between foreign-born and Finnish-born populations. Data on TB cases were obtained from the National Infectious Disease Register and denominator data on legal residents and their country of birth from the Population Information System. M. tuberculosis isolates were genotyped by spoligotyping and Mycobacterial Interspersed Repetitive Unit Variable Number Tandem Repeat (MIRU-VNTR). We characterized clusters by age, sex, origin and region of living which included both foreign-born cases and those born in Finland. During 2014-2017, 1015 TB cases were notified; 814 were confirmed by culture. The proportion of foreign-born cases increased from 33.3% to 39.0%. Foreign-born TB cases were younger (median age, 28 vs. 75 years), and had extrapulmonary TB or multidrug-TB more often than Finnish-born cases (P<0.01 for all comparisons). Foreign-born cases were born in 60 different countries; most commonly in Somalia (25.5%). Altogether 795 isolates were genotyped; 31.2% belonged to 80 different clusters (range, 2-13 cases/cluster). Fourteen (17.5%) clusters included isolates from both Finnish-born and foreign-born cases. An epidemiological link between cases was identified by (epidemiological) background information in two clusters. Although the proportion of foreign-born TB cases was considerable, our data suggests that transmission of TB between foreign and Finnish born population is uncommon.

Emerging source of infection - Mycobacterium tuberculosis in rescue dogs: a case report.

Rescue dog activity is a heavily increasing form of dog charity. Imported homeless dogs represent a reservoir of zoonotic diseases putting owners, veterinarians and pathologists repeatedly at risk. The clinical signs of tuberculosis in a dog are non-specific and diagnosis is often delayed or dismissed. We present a case of 9 months of possible exposure at home and definite exposure at laparotomy and autopsy to intestinal tuberculosis in a family dog imported from Romania to Finland. Persistent gastrointestinal symptoms started 2 years after the import. Abdominal pain, diarrhoea and vomiting proceeded and led to spontaneous death. Mycobacterium tuberculosis was identified in the liver, lymph nodes and intestine at autopsy. Exposed persons were notified and follow-up was provided, and no further infections were identified within 12 months of follow-up. The heavily increasing import of companion animals presents unexpected public health risks, such as prolonged exposure to tuberculosis, of which the general public is not aware. The dramatic consequences and high costs of tuberculosis could be reduced through accessible information of the risks of imported animals to both the general public and veterinarians, in addition to availability of rapid diagnostics and proper personal protection.

Basis for treatment of tuberculosis among HIV-infected patients in Tanzania: the role of chest x-ray and sputum culture.

BACKGROUND: Active tuberculosis (TB) is common among HIV-infected persons living in tuberculosis endemic countries, and screening for tuberculosis (TB) is recommended routinely. We sought to determine the role of chest x-ray and sputum culture in the decision to treat for presumptive TB using active case finding in a large cohort of HIV-infected patients. METHODS: Ambulatory HIV-positive subjects with CD4 counts > or = 200/mm3 entering a Phase III TB vaccine study in Tanzania were screened for TB with a physical examination, standard interview, CD4 count, chest x-ray (CXR), blood culture for TB, and three sputum samples for acid fast bacillus (AFB) smear and culture. RESULTS: Among 1176 subjects 136 (12%) were treated for presumptive TB. These patients were more frequently male than those without treatment (34% vs. 25%, respectively; p = 0.049) and had lower median CD4 counts (319/microL vs. 425/microL, respectively; p < .0001). Among the 136 patients treated for TB, 38 (28%) had microbiologic confirmation, including 13 (10%) who had a normal CXR and no symptoms. There were 58 (43%) treated patients in whom the only positive finding was an abnormal CXR. Blood cultures were negative in all patients. CONCLUSION: Many ambulatory HIV-infected patients with CD4 counts > or = 200/mm3 are treated for presumptive TB. Our data suggest that optimal detection requires comprehensive evaluation, including CXR and sputum culture on both symptomatic and asymptomatic subjects.

Isolation and automated ribotyping of Mycobacterium lentiflavum from drinking water distribution system and clinical specimens.

Automated ribotyping as a tool for identifying of nontuberculous mycobacteria was evaluated. We created a database comprising of riboprints of 60 strains, representing 32 species of nontuberculous mycobacteria. It was shown that combined ribopatterns generated after digestion with EcoRI and PvuII were distinguishable between species of both slow-growing and rapid-growing mycobacteria. The findings were in good agreement with the 16S rRNA gene sequencing results, allowing correct identification of Mycobacterium lentiflavum isolated from clinical specimens and from biofilms growing in public water distribution system. The automated ribotyping was powerful in discriminating between M. lentiflavum and closely related species M. simiae and M. palustre. Mycobacterium lentiflavum strains from drinking water biofilms were resistant to two to four antimycobacterial drugs. The drinking water distribution system may, thus, be a source of nontuberculous mycobacteria resistant to multiple drugs.

Relating the size of molecularly defined clusters of tuberculosis to the duration of symptoms.

Molecular profiling of Mycobacterium tuberculosis isolates has improved recognition of tuberculosis case clusters, but the determinants of cluster size are unknown. We hypothesized that longer duration of symptoms prior to initiation of tuberculosis therapy would be associated with increased cluster size. All patients with tuberculosis in Harris County, Texas, identified between 10/1/95 and 12/31/97 through a prospective population-based project were interviewed, had their medical records reviewed, and had M. tuberculosis isolates molecularly characterized. There were 506 symptomatic, evaluable patients in 74 clusters, ranging in size from 2 patients (32 clusters) to 61 patients (1 cluster). The median duration of symptoms was 46 days (range, 1-471 days). There was no association between the log-transformed duration of symptoms and cluster size in univariate or multivariate analysis. In multivariate analysis, age and HIV coinfection were inversely related to cluster size, but only weakly. The size of molecularly defined clusters of tuberculosis was not related to the duration of symptoms of most patients who belonged to clusters.