Sustained effect of isoniazid preventive therapy among household contacts in Brazil.

BACKGROUND: Isoniazid preventive therapy (IPT) is highly effective in preventing TB disease; however, its long-term benefit in household contacts (HHCs) of infectious TB cases is unclear.METHODS: We conducted a retrospective analysis of two household contact studies in Vitoria, ES, Brazil, between 2008 and 2015. Households with smear-positive, culture-proven TB disease were enrolled. Eligible HHCs with tuberculin skin test (TST) indurations of ≥10 mm were referred to local TB clinics and IPT was started according to national guidelines. We reviewed the national dataset information system in January 2020 to identify HHCs with a diagnosis of TB disease. Time to event and Cox proportional regression analysis were conducted to identify factors associated with TB disease.RESULTS: Of the 1097 HHCs enrolled, 654 (60%) had TST ≥10 mm; 160 (24%) initiated IPT, of whom 115 (71.9%) completed IPT, which accounts for an overall completion rate of 18% among the population at risk; 42 (6%) TB cases were identified. IPT was associated with a 71% decrease in TB disease rates (HR 0.29, 95% CI 0.10-0.82; P = 0.02) among HHCs with TST ≥10 mm. IPT effect was sustained, as TB cases in HHCs without IPT occurred along the 7.9-year follow-up, whereas all four TB cases in HHCs with IPT were diagnosed within the first 3 years after exposureCONCLUSION: Isoniazid provides long-term protection for TB disease in household contacts of culture-proven TB cases.

Sputum Mycobacterium tuberculosis mRNA as a marker of bacteriologic clearance in response to antituberculosis therapy.

mRNA is a marker of cell viability. Quantifying Mycobacterium tuberculosis mRNA in sputum is a promising tool for monitoring response to antituberculosis therapy and evaluating the efficacy of individual drugs. mRNA levels were measured in sputum specimens from patients with tuberculosis (TB) receiving monotherapy in an early bactericidal activity study of fluoroquinolones and in those receiving a standard rifampin-based regimen in an interleukin-2 (IL-2) trial. In the early bactericidal activity study, sputum for quantitative culture and mRNA analysis was collected for 2 days before and daily during 7 days of study drug administration. In the IL-2 trial, sputum was collected for quantitative culture, Bactec 460 liquid culture, and mRNA analysis throughout the intensive treatment phase. RNA was isolated from digested sputum and tested in quantitative reverse transcription-PCR assays for several gene targets. mRNA for the glyoxylate cycle enzyme isocitrate lyase declined at similar rates in patients receiving isoniazid, gatifloxicin, levofloxacin, and moxifloxacin monotherapy. Isocitrate lyase mRNA correlated highly with CFU in sputum prior to therapy and during 7 days of monotherapy in all treatment arms. Isocitrate lyase mRNA was detectable in sputum of culture-positive TB patients receiving a rifampin-based regimen for 1 month. At 2 months, sputum for isocitrate mRNA correlated more closely with growth in liquid culture than did growth on solid culture medium. Data suggest that isocitrate lyase mRNA is a reliable marker of M. tuberculosis viability.

Evaluation of low-colony-number counts of Mycobacterium tuberculosis on solid media as a microbiological marker of cross-contamination.

Low-colony-number counts on solid media are considered characteristic of cross-contamination, although they are normally observed in true-positive cultures from some groups of patients. The aim of this study was to evaluate low-yield growth cultures as a microbiological marker for cross-contamination. We evaluated 106 cultures with <15 colonies from 94 patients, and the proportions of false-positive cultures were 0.9% per sample and 1.1% per patient, which indicates that low-yield growth is not a reliable marker of cross-contamination.

Toll-like receptors blocking restores in vitro microbicidal activity in latent tuberculosis-infected subjects.

BACKGROUND: Latent tuberculous infection (LTBI) can function as a 'reservoir' for Mycobacterium tuberculosis. Given that T-regulatory cell (Treg) numbers are augmented in LTBI, it is likely that Toll-like receptors (TLRs) may have a role in Treg function. Elucidation of the immune mechanisms associated with tuberculosis (TB) development may help to control M. tuberculosis spread.OBJECTIVE: To investigate the role of TLR2, TLR4 and TLR9 in hindered in vitro microbicidal activity and increase Treg number during LTBI. DESIGN: Whole blood cell cultures from individuals with LTBI and healthy controls (HCs) infected with live M. tuberculosis H37Rv strain were used to investigate the effect of TLR2, TLR4 and TLR9 on Treg number, microbicidal activity, and interferon-gamma and interleukin (IL)10 production. RESULTS: LTBI subjects were characterised by increased Treg number and impaired microbicidal activity when compared with HCs. Specific blockade of TLR4 and TLR9 led to a significant reduction in Treg number, a decrease in IL-10 production and substantial upregulation of microbicidal activity. CONCLUSION: M. tuberculosis infection may activate TLR4 and TLR9 pathways to suppress M. tuberculosis-specific immune responses. Here, we show that activation of TLR4 and TLR9 hinder microbicidal activity during LTBI.

Multicentre evaluation of an automated BACTEC 960 system for susceptibility testing of Mycobacterium tuberculosis.

SETTING: Three mycobacteria reference laboratories in the south-eastern part of Brazil. OBJECTIVE: To evaluate the automated Mycobacteria Growth Indicator Tube (MGIT) for drug susceptibility testing of Mycobacterium tuberculosis. DESIGN: Performance of the automated BACTEC MGIT 960 (M960) system for testing M. tuberculosis susceptibility to streptomycin (SM), isoniazid (INH), rifampicin (RMP) and ethambutol (EMB) was evaluated with 95 clinical isolates and compared to the results of the radiometric BACTEC 460TB (B460) system, the proportion method (PM), and the resistance ratio method (RRM). Judicial susceptibility profiles of 88 isolates were defined based on two or more concordant results among B460, PM and RRM, and used as a reference for comparison with M960 results. RESULTS: Agreement rates between M960 and conventional methods were 95.2% with B460, 96.6% with the PM and 93.4% with the RRM. The lowest agreement rates were obtained for SM with the RRM and for EMB with B460. When comparing M960 with judicial susceptibility profiles, the agreement rate was 97.9%. The agreement rates obtained for INH and RMP were 99.2% and for SM and EMB they were 96.2% and 96.9%, respectively. The mean time to reporting the M960 results was 6.9 days. CONCLUSION: M960 offers great improvements when compared to the proportion and resistance ratio methods and would benefit patient treatment.

Early and extended early bactericidal activity of levofloxacin, gatifloxacin and moxifloxacin in pulmonary tuberculosis.

OBJECTIVE: To evaluate the early bactericidal activity (EBA) of the new fluoroquinolones levofloxacin, gatifloxacin and moxifloxacin in patients with pulmonary tuberculosis (PTB). DESIGN: Randomized, open-label trial. Forty adults with newly diagnosed smear-positive PTB (10 per arm) were assigned to receive isoniazid (INH) 300 mg, levofloxacin 1000 mg, gatifloxacin 400 mg, or moxifloxacin 400 mg daily for 7 days. Sputum for quantitative culture was collected for 2 days before and daily during 7 days of monotherapy. Bactericidal activity was estimated by measuring the decline in bacilli during the first 2 days (EBA 0-2) and last 5 days of monotherapy (extended EBA, EBA 2-7). Laboratory staff were blinded to treatment assignment. RESULTS: The EBA 0-2 of INH (0.67 log10 cfu/ml/day) was greater than that of moxifloxacin and gatifloxacin (0.33 and 0.35 log10 cfu/ml/day, respectively), but not of levofloxacin 1000 mg daily (0.45 log10 cfu/ml/day) (P = 0.14). Bactericidal activity between days 2 and 7 was similar for all three fluoroquinolones. In a pooled comparison, the EBA 2-7 of the fluoroquinolones was greater than for INH. CONCLUSION: Moxifloxacin, gatifloxacin, and high-dose levofloxacin have excellent EBA, only slightly less than for INH, and greater extended EBA. These drugs warrant further study in the treatment of drug-susceptible TB.

Infection and disease among household contacts of patients with multidrug-resistant tuberculosis.

SETTING: Urban public teaching and referral hospital in Espirito Santo, Brazil. OBJECTIVE: To assess whether rates of infection and progression to active tuberculosis (TB) differed between household contacts of patients with multidrug-resistant (MDR) and drug susceptible (DS) pulmonary tuberculosis. DESIGN: Household contacts were assessed for evidence of TB infection and disease by purified protein derivative (PPD) skin testing, physical examination, chest X-ray, and sputum smear and culture. RESULTS: Among 133 close contacts of patients with MDR-TB, 44% were PPD-positive (> or =10 mm) compared to 37% of 231 contacts of the DS-TB cases (P = 0.18, chi2 test, OR 1.2, 95%CI 0.8-2). In a multivariate logistic regression analysis, after allowance for between-household variation in PPD responses, PPD positivity among household contacts of patients with MDR-TB remained comparable to PPD positivity in contacts of patients with DS-TB (OR 2.1, 95%CI 0.7-6.5). Respectively six (4%) and 11 (4%) contacts of the MDR- and DS-TB cases were found to have active TB at the time of initial evaluation or during follow-up (P = 0.78, chi2 test). Five of six contacts of MDR-TB cases and nine of nine contacts of DS-TB cases who developed TB, and for whom drug susceptibility test results were available, had the same bacterial susceptibility profiles as their index cases. DNA fingerprinting analysis of Mycobacterium tuberculosis isolates was identical between household contacts with active TB and the index MDR or DS-TB case for all 14 pairs compared. CONCLUSION: Our data suggest that the prevalence of tuberculous infection and progression to active TB among household contacts exposed to DS and MDR-TB cases is comparable, despite a longer duration of exposure of contacts to the index case in patients with MDR-TB.

Transmission of tuberculosis in an endemic urban setting in Brazil.

SETTING: Two out-patient facilities in São Paulo, Brazil. OBJECTIVE: To study the transmission pattern of tuberculosis (TB) among human immunodeficiency virus (HIV) infected and uninfected persons in a setting endemic for TB. DESIGN: A prospective study comparing HIV-seropositive and -seronegative TB patients identified consecutively between 1 March 1995 and 1 April 1997. The patients were stratified according to their Mycobacterium tuberculosis isolate IS6110 RFLP patterns. Risk factors were sought for infection with an RFLP cluster pattern strain, inferred to represent recent transmission. RESULTS: Fifty-eight (38%) of 151 HIV-seropositive patients and 36 (25%) of 142 HIV-seronegative patients were infected with M. tuberculosis isolates that belonged to cluster patterns (OR 1.84, 95% CI 1.08-3.13). Multidrug-resistant (MDR) strains were isolated from 19 patients, all of whom were HIV seropositive; 12 (63%) of these, and 46 (35%) of 132 drug-susceptible isolates had cluster patterns (OR 3.20, 95% CI 1.08-9.77). CONCLUSION: In a TB-endemic urban setting in Brazil, the proportion of cases resulting from recent transmission appears to be greater among HIV-seropositive than among HIV-seronegative patients. A large proportion of MDR-TB (63%) cases was caused by strains that had cluster RFLP patterns, suggesting recent transmission of already resistant organisms. This type of knowledge regarding TB transmission may help to improve locally appropriate TB control programs.

Tuberculosis and drug resistance among patients seen at an AIDS Reference Center in São Paulo, Brazil.

OBJECTIVES: To assess the frequency of resistance of Mycobacterium tuberculosis to antituberculosis drugs and the factors associated with it among patients with tuberculosis (TB) and acquired immunodeficiency syndrome (AIDS). MATERIALS AND METHODS: The medical records of TB and AIDS cases diagnosed from 1992 to 1997 in a public service for AIDS care were reviewed. RESULTS: Resistance was diagnosed in 82 (19%) of 431 cases. The mean and median values between the diagnosis of AIDS and the diagnosis of TB were 214.8 days and 70.5 days, respectively. Multidrug-resistant TB (MDR TB) occurred in 11.3% of cases. Of the 186 patients with no previous treatment, 13 (6.9%) presented primary MDR TB. Of the 90 cases with previous treatment, six (6.7%) presented monoresistance to rifampin and 27 (30%) presented MDR TB. The distribution of cases with sensitive and resistant M. tuberculosis strains was homogeneous in terms of the following variables: gender, age, category of exposure to human immunodeficiency virus (HIV), alcoholism, and homelessness. Multivariate analysis showed an association between resistance and the two following variables: previous treatment and duration of AIDS prior to TB exceeding 71 days. The rates of primary multiresistance and of monoresistance to rifampin were higher than those detected in HIV-negative patients in Brazil. CONCLUSIONS: In this patient series, M. tuberculosis resistance was predominantly of the acquired type, and resistance was independently associated with previous treatment for TB and with duration of AIDS prior to TB exceeding 71 days.

IS1245 genotypic analysis of Mycobacterium avium isolates from patients in Brazil.

OBJECTIVE: Disseminated Mycobacterium avium infection is an emerging opportunistic disease among patients with acquired immunodeficiency syndrome (AIDS) in Brazil. The mode of transmission of M. avium in a developing country setting needs to be better characterized. METHODS: Mycobacterium avium strain collections in São Paulo and Rio de Janeiro were analyzed according to the strains' IS1245 DNA gel electrophoretic migration patterns. Medical records of the patients from whom M. avium isolates were available were reviewed, and their demographic characteristics were stratified according to the isolates' IS1245 DNA fingerprint patterns. RESULTS: Of 105 patients, 33 (31%) with M. avium isolated between 1990 and 1994 had strains having IS1245 patterns identical in patterns seen in isolates from two or more patients (designated as cluster pattern strains). Cluster pattern strains were isolated from 21 (39%) of 54 patients with disseminated infection (defined as infection due to M. avium isolated from a sterile site in an adult patient). Six of the cluster pattern strains were isolated only from sterile sites. In São Paulo, cluster pattern strains were significantly more likely to be isolated from patients with disseminated disease. CONCLUSIONS: These preliminary observations suggest that in large cities of Brazil, a high proportion (at least 39%) of disseminated M. avium infections in patients with AIDS results from a recent transmission. Some strains of M. avium may be more likely to cause disseminated disease than others after an infection.

Mycobacterium avium complex (MAC): an unusual potential pathogen in cerebrospinal fluid of AIDS patients.

Mycobacterium avium complex (MAC) is frequently isolated from patients with late complications of Acquired Immunodeficiency Syndrome (AIDS), especially in North America and Europe. However, its isolation from the central nervous system (CNS) has been seldom reported in these countries. MAC infections in AIDS patients in African and Latin American countries are believed to be uncommon. We report the isolation of MAC from cerebrospinal fluid (CSF) of 11 AIDS patients out of 1723 (0.63%) seen at "Centro de Referência e Treinamento-AIDS", São Paulo and discuss the significance of its isolation.

Drug resistance of M. tuberculosis isolated from patients with HIV infection seen at an AIDS Reference Center in São Paulo, Brazil.

M. tuberculosis-positive cultures were obtained from 228 patients seen in our service and drug sensitivity assays were carried out from January 1992 to December 1994. A survey of the medical records of these patients showed resistance to one or more drugs in 47 (20.6%), 25 of whom (10.9%), who reported previous treatment, were considered to have acquired resistance. Among the antecedents investigated, only previous treatment and alcoholism were the factors independently associated with the occurrence of resistance. The survival of patients with resistant strains was lower than that of patients attacked by non-resistant M. tuberculosis. We conclude that in the present series M. tuberculosis resistance to tuberculostatic agents was predominantly of the acquired type.

Bacterial agents isolated from cerebrospinal fluid of patients with acquired immunodeficiency syndrome (AIDS) and neurological complications.

Cerebrospinal fluid (CSF) samples from 2083 patients with acquired immunodeficiency syndrome (AIDS) and neurological complications were bacteriologically examined during a period of 7 years (1984-1990). The percentage of patients who had at least one bacterial agent cultured from the CSF was 6.2%. Mycobacterium tuberculosis was the most frequently isolated agent (4.3%), followed by Mycobacterium avium complex or MAC (0.7%), Pseudomonas spp (0.5%), Enterobacter spp (0.4%), and Staphylococcus aureus (0.3%). Among 130 culture positive patients, 89 (68.5%) had M. tuberculosis and 15 (11.6%) had MAC. The frequency of bacterial isolations increased from 1988 (5.2%) to 1990 (7.2%), partly due to the increase in MAC isolations. Bacterial agents were more frequently isolated from patients in the age group 21-30 years and from women (p < 0.05).

Mycobacterium avium complex (MAC) isolated from AIDS patients and the criteria required for its implication in disease.

Before the AIDS pandemia, the Mycobacterium avium complex (MAC) was responsible in most cases for the pneumopathies that attack patients with basic chronic pulmonary diseases such as emphysema and chronic bronchitis. In 1981, with the advent of the acquired immunodeficiency syndrome (AIDS), MAC started to represent one of the most frequent bacterial diseases among AIDS patients, with the disseminated form of the disease being the major clinical manifestation of the infection. Between January 1989 and February 1991, the Section of Mycobacteria of the Adolfo Lutz Institute, São Paulo, isolated MAC from 103 patients by culturing different sterile and no-sterile processed specimens collected from 2304 patients seen at the AIDS Reference and Training Center and/or Emilio Ribas Infectology Institute. Disseminated disease was diagnosed in 29 of those patients on the basis of MAC isolation from blood and/or bone marrow aspirate. The other 74 patients were divided into categories highly (5), moderately (26) and little suggestive of disease (43) according to the criteria of DAVIDSON (1989). The various criteria for MAC isolation from sterile and non-sterile specimens are discussed.

Smoking and 2-month culture conversion during anti-tuberculosis treatment.

OBJECTIVE: To investigate risk factors for delayed sputum culture conversion to negative during anti-tuberculosis treatment, with an emphasis on smoking. DESIGN: Nested case-control study of adults with non-cavitary, culture-confirmed pulmonary tuberculosis (TB) participating in an anti-tuberculosis treatment trial in Brazil. A case of delayed culture conversion was a patient who remained culture-positive after 2 months of treatment. Odds ratios with 95% confidence intervals were calculated. RESULTS: Fifty-three cases and 240 control patients were analyzed. Smokers had three-fold greater odds of remaining culture-positive after 2 months of treatment (P = 0.007) than non-smokers, while smokers and ex-smokers who smoked >20 cigarettes a day had two-fold greater odds of remaining culture-positive after 2 months of treatment (P = 0.045). CONCLUSION: Cigarette smoking adversely affects culture conversion during anti-tuberculosis treatment. Support for smoking cessation should be considered to improve outcomes in TB control programs.

Contribution of the Ogawa-Kudoh swab culture method to the diagnosis of pulmonary tuberculosis in Brazil.

OBJECTIVE: To analyse the contribution of the Ogawa-Kudoh (O-K) swab culture method to the diagnosis of pulmonary tuberculosis (PTB) in four different regions of Brazil. DESIGN: This study was carried out in two phases. Phase 1 was designed to compare the direct swab culture method (O-K) with the culture concentrated method (N-acetyl-L-cysteine-sodium hydroxide [NALC-NaOH]); for this purpose, 569 sputum samples were cultured by both methods. Phase 2 was carried out to assess the contribution of the O-K method to the diagnosis of PTB in four different regions in Brazil, based on the evaluation of 19,163 sputum samples. RESULTS: In the first phase of the study, O-K culture had a sensitivity of 94.8% and specificity of 99.8% in cases confirmed by NALC-NaOH/Löwenstein-Jensen (LJ) culture. In the second phase of the study, the overall contribution of O-K culture compared to acid-fast bacilli (AFB) examination (AFB-/culture+) to the diagnosis of PTB was 29.8%. CONCLUSION: O-K culture contributes significantly to the diagnosis of smear-negative PTB. Importantly, this method allows the recovery of clinical isolates in areas where use of the standard culture centrifuge is impossible, indicating that the O-K swab culture method should become a standard method for TB diagnosis in these regions.

Reduction of contamination of mycobacterial growth indicator tubes using increased PANTA concentration.

We assessed the effect of a double concentration of supplemental polymyxin B, amphotericin B, nalidixic acid, trimethoprim and azlocillin (PANTA) added to the Mycobacterial Growth Indicator Tube (MGIT) on contamination and positivity rates in 216 sputum cultures. Contamination rates were respectively 12.9% and 5.5% for samples processed using standard and double PANTA concentrations (P = 0.0001, McNemar's test). Thirty-five per cent of cultures performed using standard PANTA and 36.5% of those performed using two-fold PANTA concentrations were positive for Mycobacterium tuberculosis, compared to 25.9% of cultures inoculated on Ogawa medium. These results suggest that the use of MGIT with 2× PANTA may be useful in reducing culture contamination without reducing the diagnostic yield.

Spatial patterns of pulmonary tuberculosis incidence and their relationship to socio-economic status in Vitoria, Brazil.

OBJECTIVE: To investigate spatial patterns of the incidence of pulmonary tuberculosis (TB) and its relationship with socio-economic status in Vitoria, Espirito Santo, Brazil. DESIGN: In a 4-year, retrospective, territory-based surveillance study of all new pulmonary TB cases conducted in Vitoria between 2002 and 2006, spatial patterns of disease incidence were compared using spatial clustering statistics (Anselin's local indicators of spatial association [LISA] and Getis-Ord Gi* statistics), smoothed empirical Bayes estimates and model-predicted incidence rates. Spatial Poisson models were fit to examine the relationship between socio-economic status and TB incidence. RESULTS: A total of 651 TB cases were reported across 78 neighborhoods, with rates ranging from 0 to 129 cases per 100,000 population. Moran's I indicated strong spatial autocorrelation among incidence rates (0.399, P < 0.0001), and four areas of high incidence were identified by LISA and Gi* statistics. Smoothed spatial empirical Bayes estimates demonstrate that two of these areas range from 70 to 90 cases/100,000, while the other two range from 40 to 70 cases/100,000. TB incidence and socio-economic status had a significant curvilinear relationship (P = 0.02). CONCLUSIONS: Data derived from these spatial statistical tools will help TB control programs to allocate TB resources to those populations most at risk of increasing TB rates and to target areas where TB control efforts need to be concentrated.

Delay in diagnosis of pulmonary tuberculosis at a primary health clinic in Vitoria, Brazil.

SETTING: Primary health clinics in Vitoria, Espirito Santo, Brazil. OBJECTIVE: To identify risk factors associated with patient and health care delays among patients seeking care at primary health clinics. METHODS: A prospective study among tuberculosis (TB) patients diagnosed in Vitoria between 1 January 2003 and 30 December 2007. A questionnaire ascertained the date of onset and duration of TB symptoms and medical records were reviewed. Between-group distributions of delay were compared and multivariate logistic regression was performed. RESULTS: Of 304 patients, 296 (97%) reported at least one TB symptom presenting for the first time to a qualified health service; 244 (80%) reported cough > 3 weeks. Median health care delay was 30 days (range 5-68), and median total delay was 110 days (range 26-784). Multivariate analysis revealed any cough (OR(adj) 7.35, 95%CI 2.40-22.5) and weight at TB diagnosis < 60 kg (OR(adj) 5.92, 95%CI 1.83-19.1) to be associated with patient delay of ≥ 30 days. Factors increasing risk of prolonged delay (≥ 90 days) were age ≥ 30 years (OR(adj) 1.93, 95%CI 1.09-3.43) and chest pain (OR(adj) 2.42, 95%CI 1.29-4.53). CONCLUSION: Improving health care workers' education regarding TB symptoms and implementing active case finding in targeted populations may reduce delays.

Comparison of two concentrations of NALC-NaOH for decontamination of sputum for mycobacterial culture.

This study compared the effect of using two different concentrations of sodium hydroxide (NaOH) in the N-acetyl-L-cysteine-sodium hydroxide (NALC-NaOH) method for sputum decontamination on smear and culture positivity and the proportion of contaminated cultures: 14% of cultures were contaminated using the standard final 1% NaOH concentration during processing compared to 11% contaminated cultures using a final 1.25% NaOH concentration (P < 0.008). The proportion of cultures positive for mycobacteria decreased from 21% to 11% for sputum processed with 1% and 1.25% final NaOH concentrations, respectively (P < 0.001). Our findings suggest that a small reduction in culture contamination did not justify the considerable loss of positive cultures.