PCR colorimetric dot-blot assay and clinical pretest probability for diagnosis of Pulmonary Tuberculosis in Smear-Negative patients

Background  

Smear-negative pulmonary tuberculosis (SNPTB) accounts for 30% of Pulmonary Tuberculosis (PTB) cases reported annually in developing nations. Polymerase chain reaction (PCR) may provide an alternative for the rapid detection of Mycobacterium tuberculosis (MTB); however little data are available regarding the clinical utility of PCR in SNPTB, in a setting with a high burden of TB/HIV co-infection.     

The presence of a booster phenomenon among contacts of active pulmonary tuberculosis cases: a retrospective cohort

Background  

Assuming a higher risk of latent tuberculosis (TB) infection in the population of Rio de Janeiro, Brazil, in October of 1998 the TB Control Program of Clementino Fraga Filho Hospital (CFFH) routinely started to recommend a two-step tuberculin skin test (TST) in contacts of pulmonary TB cases in order to distinguish a boosting reaction due to a recall of delayed hypersensitivity previously established by infection with Mycobacterium tuberculosis (M.tb) or BCG vaccination from a tuberculin conversion. The aim of this study was to assess the prevalence of boosted tuberculin skin tests among contacts of individuals with active pulmonary tuberculosis (TB).     

Evaluation of oral antiseptic rinsing before sputum collection to reduce contamination of mycobacterial cultures

To assess whether rinsing with oral antiseptics before sputum collection would reduce contamination of mycobacterial cultures, 120 patients with suspected tuberculosis were randomly assigned to rinse with chlorhexidine or cetylpyridinium mouthwash before collection. The culture contamination rate was significantly lower after rinsing with chlorhexidine before collection, especially for cultures grown in MGIT medium.     

Prevalence of pulmonary tuberculosis among respiratory symptomatic subjects in an out-patient primary health unit.

SETTING: Out-patient primary health unit (OPHU) in Rio de Janeiro City, Brazil. OBJECTIVE: To evaluate the impact on the detection of tuberculosis (TB) cases of reducing the time of respiratory symptoms from 'cough > or = 3 weeks' to 'cough > or = 1 week' as a criteria for TB case finding among individuals visiting an OPHU for any other reason. DESIGN: Cross-sectional study. RESULTS: During the period of the study, 10.7% (765/ 7174) of subjects reported cough > or = 1 week. Among 542 subjects enrolled in the study with cough > or = 1 week, 15 (2.7%) cases were diagnosed with pulmonary tuberculosis (PTB, 2767/100000). The probability of detecting TB in the OPHU setting among subjects seeking care for respiratory symptoms was significantly higher than among those presenting to the OPHU for other reasons (OR 31.5, 95% CI 4.1-241.9; P < 0.0001). The probability of identifying TB among patients seeking care due to respiratory symptoms was not influenced by the duration of cough (P = 0.7). CONCLUSION: These findings suggest that the screening criteria for TB case finding of cough for less than the usual 3 weeks among patients who attend a health facility due to respiratory symptoms in settings with a high prevalence of TB may significantly improve the proportion of TB cases diagnosed.     

Latent tuberculosis infection among undergraduate medical students in Rio de Janeiro State, Brazil.

SETTING: Five medical schools in three cities with different tuberculosis (TB) incidence rates in Rio de Janeiro State, Brazil. OBJECTIVE: To estimate prevalence of and associated factors for latent tuberculosis infection (LTBI) among medical students. DESIGN: A cross-sectional survey was conducted among undergraduate students in pre-clinical, early and late clinical years from schools in cities with low (28/100,000), intermediate (63/100,000) and high (114/100,000) TB incidence rates. Information on socio-demographic profile, previous BCG vaccination, potential TB exposure, co-morbidity and use of respiratory protective masks was obtained. A tuberculin skin test (TST) was performed using the Mantoux technique by an experienced professional. A positive TST, defined as induration > or = 10 mm, was considered LTBI. RESULTS: LTBI prevalence was 6.9% (95%CI 5.4-8.6). In multivariate analysis, male sex (adjusted odds ratio [aOR] 1.8; 95% CI 1.1-3.0), late clinical years (aOR 1.9; 95% CI 1.01-3.5), intermediate TB incidence (aOR 4.3; 95% CI 1.3-14.6) and high TB incidence in the city of medical school (aOR 5.1; 95% CI 1.6-16.8) were significantly associated with LTBI. CONCLUSIONS: The higher prevalence of LTBI in late clinical years suggests that medical students are at increased risk for nosocomial Mycobacterium tuberculosis infection. The implementation of a TB control program may be necessary in medical schools, particularly in cities with higher TB incidence.     

Epidemiological study of Brazilian purpuric fever. Epidemic in a locality of S?o Paulo state (Brazil), 1986]

A case control model was used in the study of an outbreak of Brazilian purpuric fever BPF which occurred in Serrana, S. Paulo State, Brazil, in 1986. Three hypotheses were raised: 1--purulent conjunctivitis is associated with BPF; 2--a cluster effect occurs in BPF; 3--respiratory symptoms may be a variation of the clinical picture of the disease. Numerical values were attributed to different findings, as follows: fever = 5; diarrhea and/or vomiting = 1; haemorrhagic findings = 3; thrombocytopenia and/or leukopenia = 3; Haemophilus aegyptius positive hemoculture and/or Haemophilus aegyptius positive cerebrospinal fluid culture and/or H. a. oropharynx culture = 7; Waterhouse Friedrichsen syndrome = 7. Those cases for which the sum total of points reached or exceeded 13 were considered as confirmed and those obtaining between 8 and 12 were considered as suspect. Children with a score below 5 were taken as control cases. Cases and controls were matched according to sex, age and socioeconomic level. The total groups studied included 14 confirmed cases, 38 suspect cases and 78 controls. It was concluded that purpuric fever is strongly associated with previous and/or present purulent conjunctivities; a cluster effect seems to occur; respiratory symptoms such as coughing and/or coryza were not associated with BPF.     

Spatial distribution of M. tuberculosis-HIV coinfection in São Paulo State, Brazil, 1991-2001

OBJECTIVE: To assess the spatial pattern of tuberculosis incidence in relation to the AIDS epidemic, with the aim of investigating the geographical influence on causality. METHODS: All AIDS cases from State of S?o Paulo, notified to the Brazilian Ministry of Health between 1991 and 2001, were included. The cases were stratified by municipality, by administrative health regions, AIDS transmission categories, gender and years since diagnosis. A Gaussian geostatistical model was used to construct a thematic risk map, utilizing the tuberculosis incidence among AIDS cases as the response variable. RESULTS: Exploratory analysis showed two patterns of AIDS incidence: one for the state capital, and another, with increasing risk, for the other municipalities. The more populous regions presented higher risk of tuberculosis transmission, with a pattern that matched the land occupation pattern, from east to west. The health regions with the highest AIDS incidence coefficients (per 10,000 inhabitants) were Santos (53.5), S?o José do Rio Preto (43.1), Ribeir?o Preto (42.4) and S?o Paulo (40.3). The health regions with greatest tuberculosis incidence among AIDS cases were Santos (44.9%), Franco da Rocha (39.9%), Osasco (39.6%) and S?o Paulo (38.9%). CONCLUSIONS: The results allow the conclusion that geographical coordinates presented an association with tuberculosis risk, but not with AIDS risk.     

Accessibility to tuberculosis treatment: assessment of health service performance

The aim of this study was to assess the accessibility of patients to the treatment of tuberculosis in Ribeir?o Preto, countryside of S?o Paulo State. Evaluation study type, with a quantity approach. Interviews with 100 patients initiated on anti-tuberculosis chemotherapy between 2006-2007 were conducted, using a structured questionnaire based on the Primary Care Assessment Tool (PCAT). Data were analyzed through variance analysis. There was a positive feedback regarding to organizational accessibility, however, the performance of health services has been unsatisfactory in providing transportation vouchers and in addressing the need to use transport for displacement to the health unit, resulting in indirect costs to patients. The services with the highest number of patients treated were those with higher irregularity in the conduct of home visits, showing that the availability of resources (human, material and time) and the organization of care may influence the accessibility to treatment.     

A statistical model investigating the prevalence of tuberculosis in New York City using counting processes with two change-points

We considered a Bayesian analysis for the prevalence of tuberculosis cases in New York City from 1970 to 2000. This counting dataset presented two change-points during this period. We modelled this counting dataset considering non-homogeneous Poisson processes in the presence of the two-change points. A Bayesian analysis for the data is considered using Markov chain Monte Carlo methods. Simulated Gibbs samples for the parameters of interest were obtained using WinBugs software.