The changing epidemiology of acquired drug-resistant tuberculosis in San Francisco, USA

Incidence and predictors of acquired resistance to second-line antituberculosis drugs during the course of multi-drug resistant tuberculosis treatment: protocol for a systematic review and meta-analysis

INTRODUCTION

To date, acquired resistance to second-line antituberculosis drugs (SLDs) during multi-drug resistant tuberculosis (MDR-TB) treatment is becoming a public health concern. Different studies have assessed the incidence of acquired resistance to SLDs. However, the findings are inconsistent and there is limited global evidence. Thus, we are going to assess the incidence and predictors of acquired resistance to SLDs during MDR-TB treatment.

METHODS AND ANALYSIS

We designed this protocol following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist. Electronic databases and grey literature sources will be searched systematically for articles published up to 25 March 2023. Studies reporting the incidence and predictors of acquired resistance to SLDs in MDR-TB patients will be explored. The studies will be managed using Endnote X8 citation manager and a stepwise approach will be followed to select studies. Data will be summarised using Microsoft Excel 2016 spreadsheet. A Newcastle-Ottawa Scale quality assessment and cochrane risk-of-bias tools will be used to assess the study's quality. The authors will independently search databases, select studies, assess the study's quality and extract data. Data will be analysed using STATA V.17 software. We will estimate the pooled incidence of acquired resistance with 95% CI. In addition, the pooled effect measures (OR, HR, risk ratio) with their 95% CI will be estimated. Heterogeneity will be assessed using the I2 statistics. Publication bias will be assessed using funnel plot and Egger's test. A subgroup analysis will be conducted for the primary outcome (acquired resistance) per each study characteristics such as WHO regional category, country's TB/MDR-TB burden, data collection period and per the specific second-line anti-TB drug.

ETHICS AND DISSEMINATION

Since this study will be based on data extraction from published studies, ethical approval is not mandatory. The study will be published in peer-reviewed scientific journals and the findings will be presented at different scientific conferences.

PROSPERO REGISTRATION NUMBER

CRD42022371014.

A new blood-based RNA signature (R9), for monitoring effectiveness of tuberculosis treatment in a South Indian longitudinal cohort

Tuberculosis (TB) treatment involves a multidrug regimen for six months, and until two months, it is unclear if treatment is effective. This delay can lead to the evolution of drug resistance, lung damage, disease spread, and transmission. We identify a blood-based 9-gene signature using a computational pipeline that constructs and interrogates a genome-wide transcriptome-integrated protein-interaction network. The identified signature is able to determine treatment response at week 1-2 in three independent public datasets. Signature-based R9-score correctly detected treatment response at individual timepoints (204 samples) from a newly developed South Indian longitudinal cohort involving 32 patients with pulmonary TB. These results are consistent with conventional clinical metrics and can discriminate good from poor treatment responders at week 2 (AUC 0.93(0.81-1.00)). In this work, we provide proof of concept that the R9-score can determine treatment effectiveness, making a case for designing a larger clinical study.

Cathepsins and Their Endogenous Inhibitors in Host Defense During Mycobacterium tuberculosis and HIV Infection

The moment a very old bacterial pathogen met a young virus from the 80's defined the beginning of a tragic syndemic for humanity. Such is the case for the causative agent of tuberculosis and the human immunodeficiency virus (HIV). Syndemic is by definition a convergence of more than one disease resulting in magnification of their burden. Both pathogens work synergistically contributing to speed up the replication of each other. Mycobacterium tuberculosis (Mtb) and HIV infections are in the 21st century among the leaders of morbidity and mortality of humankind. There is an urgent need for development of new approaches for prevention, better diagnosis, and new therapies for both infections. Moreover, these approaches should consider Mtb and HIV as a co-infection, rather than just as separate problems, to prevent further aggravation of the HIV-TB syndemic. Both pathogens manipulate the host immune responses to establish chronic infections in intracellular niches of their host cells. This includes manipulation of host relevant antimicrobial proteases such as cathepsins or their endogenous inhibitors. Here we discuss recent understanding on how Mtb and HIV interact with cathepsins and their inhibitors in their multifactorial functions during the pathogenesis of both infections. Particularly we will address the role on pathogen transmission, during establishment of intracellular chronic niches and in granuloma clinical outcome and tuberculosis diagnosis. This area of research will open new avenues for the design of innovative therapies and diagnostic interventions so urgently needed to fight this threat to humanity.

Temporal Factors and Missed Doses of Tuberculosis Treatment. A Causal Associations Approach to Analyses of Digital Adherence Data

Rationale: Tuberculosis treatment lasts for 6 months or more. Treatment adherence is critical; regimen length, among other factors, makes this challenging. Globally, analyses mapping common types of nonadherence are lacking. For example, is there a greater challenge resulting from early treatment cessation (discontinuation) or intermittent missed doses (suboptimal dosing implementation)? This is essential knowledge for the development of effective interventions and more “forgiving” regimens, as well as to direct national tuberculosis programs.

Objectives: To granularly describe how patients take their tuberculosis medication and the temporal factors associated with missed doses.

Methods: The present study included patients with pulmonary tuberculosis enrolled in the control arm of a pragmatic, cluster-randomized trial in China of electronic reminders to improve treatment adherence. Treatment was the standard 6-month course (180 d), dosed every other day (90 doses). Medication monitor boxes recorded adherence (box opening) without prompting reminders. Patterns of adherence were visualized and described. Mixed-effects logistic regression models examined the temporal factors associated with per-dose suboptimal dosing implementation, adjusting for clustering within a participant. Cox regression models were used to examine the association between early suboptimal dosing implementation and permanent discontinuation.

Results: Across 780 patients, 16,794 (23.9%) of 70,200 doses were missed, 9,487 of which were from suboptimal dosing implementation (56.5%). By 60 days, 5.1% of participants had discontinued, and 14.4% had discontinued by 120 days. Most participants (95.9%) missed at least one dose. The majority of gaps were of a single dose (71.4%), although 22.6% of participants had at least one gap of 2 weeks or more. In adjusted models, the initiation–continuation phase transition (odds ratio, 3.07 [95% confidence interval, 2.68–3.51]) and national holidays (1.52 [1.39–1.65]) were associated with increased odds of suboptimal dosing implementation. Early-stage suboptimal dosing implementation was associated with increased discontinuation rates.

Conclusions: Digital tools provide an unprecedented step change in describing and addressing nonadherence. In our setting, nonadherence was common; patients displayed a complex range of patterns. Dividing nonadherence into suboptimal dosing implementation and discontinuation, we found that both increased over time. Discontinuation was associated with early suboptimal dosing implementation. These apparent causal associations between temporal factors and nonadherence present opportunities for targeted interventions.

Clinical trial registered with the ISRCTN Registry (ISRCTN46846388).

Bayesian Spatial Survival Analysis of Duration to Cure among New Smear-Positive Pulmonary Tuberculosis (PTB) Patients in Iran, during 2011-2018

Mycobacterium tuberculosis is the causative agent of tuberculosis (TB), and pulmonary TB is the most prevalent form of the disease worldwide. One of the most concrete actions to ensure an effective TB control program is monitoring TB treatment outcomes, particularly duration to cure; but, there is no strong evidence in this respect. Thus, the primary aim of this study was to examine the possible spatial variations of duration to cure and its associated factors in Iran using the Bayesian spatial survival model. All new smear-positive PTB patients have diagnosed from March 2011 to March 2018 were included in the study. Out of 34,744 patients, 27,752 (79.90%) patients cured and 6992 (20.10%) cases were censored. For inferential purposes, the Markov chain Monte Carlo algorithms are applied in a Bayesian framework. According to the Bayesian estimates of the regression parameters in the proposed model, a Bayesian spatial log-logistic model, the variables gender (male vs. female, TR = 1.09), altitude (>750 m vs. ≤750 m, TR = 1.05), bacilli density in initial smear (3+ and 2+ vs. 1–9 Basil & 1+, TR = 1.09 and TR = 1.02, respectively), delayed diagnosis (>3 months vs. <1 month, TR = 1.02), nationality (Iranian vs. other, TR = 1.02), and location (urban vs. rural, TR = 1.02) had a significant influence on prolonging the duration to cure. Indeed, pretreatment weight (TR = 0.99) was substantially associated with shorter duration to cure. In summary, the spatial log-logistic model with convolution prior represented a better performance to analyze the duration to cure of PTB patients. Also, our results provide valuable information on critical determinants of duration to cure. Prolonged duration to cure was observed in provinces with low TB incidence and high average altitude as well. Accordingly, it is essential to pay a special attention to such provinces and monitor them carefully to reduce the duration to cure while maintaining a focus on high-risk provinces in terms of TB prevalence.

All nonadherence is equal but is some more equal than others? Tuberculosis in the digital era

Adherence to treatment for tuberculosis (TB) has been a concern for many decades, resulting in the World Health Organization's recommendation of the direct observation of treatment in the 1990s. Recent advances in digital adherence technologies (DATs) have renewed discussion on how to best address nonadherence, as well as offering important information on dose-by-dose adherence patterns and their variability between countries and settings. Previous studies have largely focussed on percentage thresholds to delineate sufficient adherence, but this is misleading and limited, given the complex and dynamic nature of adherence over the treatment course. Instead, we apply a standardised taxonomy - as adopted by the international adherence community - to dose-by-dose medication-taking data, which divides missed doses into 1) late/noninitiation (starting treatment later than expected/not starting), 2) discontinuation (ending treatment early), and 3) suboptimal implementation (intermittent missed doses). Using this taxonomy, we can consider the implications of different forms of nonadherence for intervention and regimen design. For example, can treatment regimens be adapted to increase the "forgiveness" of common patterns of suboptimal implementation to protect against treatment failure and the development of drug resistance? Is it reasonable to treat all missed doses of treatment as equally problematic and equally common when deploying DATs? Can DAT data be used to indicate the patients that need enhanced levels of support during their treatment course? Critically, we pinpoint key areas where knowledge regarding treatment adherence is sparse and impeding scientific progress.

Rifampin-resistant Tuberculosis in the United States, 1998-2014

BACKGROUND

Monoresistance to rifamycins necessitates longer and more toxic regimens for tuberculosis (TB). We examined characteristics and mortality associated with rifampin-monoresistant (RMR) TB in the United States.

METHODS

We analyzed Mycobacterium tuberculosis culture-positive cases reported to the National TB Surveillance System (excluding California) between 1998 and 2014. We defined RMR TB found on initial drug susceptibility testing and possible acquired rifampin-resistant (ARR) TB. We assessed temporal trends in RMR TB. For both classifications of rifampin resistance, we calculated adjusted risk ratios (adjRRs) and 95% confidence intervals (CIs) for characteristics associated with mortality when compared with drug-susceptible TB in multivariable models using backward selection.

RESULTS

Of 180 329 TB cases, 126 431 (70%) were eligible for analysis, with 359 (0.28%) of eligible cases reported as RMR. The percentage of RMR TB cases with HIV declined 4% annually between 1998 and 2014. Persons with HIV and prior TB were more likely to have RMR TB (adjRR, 25.9; 95% CI, 17.6-38.1), as were persons with HIV and no prior TB (adjRR, 3.1; 95% CI, 2.4-4.1) vs those without either characteristic, controlling for other statistically significant variables. RMR cases had greater mortality (adjRR, 1.4; 95% CI, 1.04-1.8), controlling for HIV and other variables. Persons with HIV had greater risk of ARR than persons without HIV (adjRR, 9.6; 95% CI, 6.9-13.3), and ARR was also associated with increased mortality, controlling for HIV and other variables.

CONCLUSIONS

All forms of rifampin resistance were positively associated with HIV infection and increased mortality.

IMPACT study on intervening with a manualised package to achieve treatment adherence in people with tuberculosis: protocol paper for a mixed-methods study, including a pilot randomised controlled trial

INTRODUCTION

Compared with the rest of the UK and Western Europe, England has high rates of the infectious disease tuberculosis (TB). TB is curable, although treatment is for at least 6 months and longer when disease is drug resistant. If patients miss too many doses (non-adherence), they may transmit infection for longer and the infecting bacteria may develop resistance to the standard drugs used for treatment. Non-adherence may therefore risk both their health and that of others. Within England, certain population groups are thought to be at higher risk of non-adherence, but the factors contributing to this have been insufficiently determined, as have the best interventions to promote adherence. The objective of this study was to develop a manualised package of interventions for use as part of routine care within National Health Services to address the social and cultural factors that lead to poor adherence to treatment for TB disease.

METHODS AND ANALYSIS

This study uses a mixed-methods approach, with six study components. These are (1) scoping reviews of the literature; (2) qualitative research with patients, carers and healthcare professionals; (3) development of the intervention; (4) a pilot randomised controlled trial of the manualised intervention; (5) a process evaluation to examine clinical utility; and (6) a cost analysis.

ETHICS AND DISSEMINATION

This study received ethics approval on 24 December 2018 from Camberwell St. Giles Ethics Committee, UK (REC reference 18/LO/1818). Findings will be published and disseminated through peer-reviewed publications and conference presentations, published in an end of study report to our funder (the National Institute for Health Research, UK) and presented to key stakeholders.

TRIAL REGISTRATION NUMBER

ISRCTN95243114 SECONDARY IDENTIFYING NUMBERS: University College London/University College London Hospitals Joint Research Office 17/0726.National Institute for Health Research, UK 16/88/06.

Predictors for Pulmonary Tuberculosis Treatment Outcome in Denmark 2009-2014

Monitoring of tuberculosis (TB) treatment outcome is essential to ensure an effective TB control program. In this nationwide retrospective cohort study from Denmark we present TB treatment outcome rates and risk factors associated with an unfavourable outcome. All patients notified with pulmonary TB from 2009 through 2014 were included. Logistic regression analyses were used to identify risk factors for unfavourable outcome. In total, 1681 pulmonary TB cases were included. TB treatment success rates increased during the study period. In 2014, the treatment success rate reached 85% for new culture positive cases whereas 7% cases interrupted treatment. The mortality decreased during the study period from 12.3% to 4.1%. Several risk factors associated with unfavourable outcome were identified in a multivariable model: male (OR: 2.56), Greenlandic origin (OR: 1.80), abuse of alcohol (OR: 2.90), history of mental disorder (OR: 2.46), and anaemia at time of treatment initiation (OR: 1.92). In a TB low incidence setting such as the Danish, it is important to maintain focus on preventing an unfavourable TB outcome. Patient management and treatment can be optimized by taking into consideration risk factors such as those identified in the present study.

Rifampicin-resistant tuberculosis among known HIV-infected patients in Oyo State, Nigeria

A major opportunistic infection among HIV-infected people is tuberculosis (TB). It accelerates the deadly progression of HIV which results in further decline in the patient's immune status and early death. More than 9 million people suffer from this debilitating coinfection worldwide. More worrisome is the fact that some patients now develop resistance to rifampicin, a first-line drug against TB. This study therefore aimed at determining the rifampicin-resistant TB prevalence rate among known HIV-positive patients in Oyo State. This cross-sectional study was performed by collecting suitable sputum samples from 397 known HIV patients who attended ART Clinic between January and December 2017. The samples were analyzed using the GeneXpert machine, a real-time polymerase chain reaction-based equipment. Of the total 397 tested, 172 (43.3%) were male while 225 (56.7%) were females. Fifty (12.6%) of the 397 known HIV patients tested positive to TB and 6 (12%) of the 50 were resistant to rifampicin. Four (2.3%) of the 172 males had rifampicin-resistant TB and 2 (0.9%) of the 225 females were resistant to rifampicin. Age group 31-40 years was the most affected with pulmonary TB while age group 10-20 years was the most affected with rifampicin-resistant TB. Six (1.5%) of the total 397 were rifampicin resistant. In conclusion, strict compliance with the infection control measures is strongly advocated for to prevent further transmission of Mycobacterium tuberculosis to people living with HIV most of whom have their immune system already weakened.

Immunodeficiency and Intermittent Dosing Promote Acquired Rifamycin Monoresistance in Murine Tuberculosis

More-permissive preclinical models may be useful in evaluating antituberculosis regimens for their propensity to select drug-resistant mutants. To evaluate whether acquired rifamycin monoresistance could be recapitulated in mice and, if so, to evaluate the effects of immunodeficiency, intermittent dosing, and drug exposures, athymic nude and BALB/c mice were infected. Controls received daily rifapentine alone or 2 months of rifampin, isoniazid, pyrazinamide, and ethambutol, followed by 4 months of rifampin/isoniazid, either daily or twice weekly with one of two isoniazid doses. Test groups received the same intensive regimen followed by once-weekly rifapentine or isoniazid/rifapentine with rifapentine doses of 10, 15, or 20 mg/kg of body weight plus one of two isoniazid doses. All combination regimens rendered BALB/c mouse cultures negative but selected mutants resistant to isoniazid (8.5%, 12/140) or rifampin (3.5%, 5/140) in nude mice (P < 0.001). Intermittently dosed intensive-phase therapy selected isoniazid and rifampin resistance in 10% (8/80, P < 0.001) and 20% (16/80, P = 0.009) of nude mice, respectively, compared to 0% treated with a daily regimen. Once-weekly rifapentine-containing continuation-phase regimens selected rifampin-resistant mutants at a rate of 18.0% (18/100, P = 0.035 compared to rifampin/isoniazid regimens). Higher isoniazid doses in the intermittent-treatment control regimen and higher rifapentine doses in once-weekly regimens were associated with less selection of isoniazid resistance. Acquired resistance, including rifamycin monoresistance, was more likely to occur in nude mice despite administration of combination therapy. These results recapitulate clinical outcomes and indicate that nude mice may be useful for evaluating the ability of novel regimens to prevent the selection of resistance.

Low Frequency of Acquired Isoniazid and Rifampicin Resistance in Rifampicin-Susceptible Pulmonary Tuberculosis in a Setting of High HIV-1 Infection and Tuberculosis Coprevalence

Background

We estimated the incidence of acquired isoniazid and rifampicin resistance in rifampicin-susceptible tuberculosis in a setting of high human immunodeficiency virus type 1 (HIV-1) infection and tuberculosis coprevalence.

Methods

GeneXpert MTB/RIF–confirmed patients with rifampicin-susceptible tuberculosis were recruited at antituberculosis treatment initiation in Khayelitsha, South Africa. Liquid culture and adherence assessment were performed at 2 and 5–6 months. MTBDRplus was performed on mycobacteria-positive cultures to ascertain acquired drug resistance (ADR). Spoligotyping and whole-genome sequencing were performed to ascertain homogeneity between baseline isolates and isolates with ADR. Baseline isolates were retrospectively tested for isoniazid monoresistance. An electronic database review was performed to ascertain tuberculosis recurrences.

Results

A total of 306 participants (62% with HIV-1 coinfection, of whom 71% received antiretroviral therapy) were recruited. Ascertainment of outcomes was complete for 284 participants. Five acquired a resistant Mycobacterium tuberculosis strain during or subsequent to treatment. One strain was confirmed to have ADR, 2 were confirmed as causing exogenous reinfection, and 2 were unrecoverable for genotyping. Incident ADR was estimated to have ranged from 0.3% (95% confidence interval [CI], .1%–1.9%; 1 of 284 participants) to 1% (95% CI, .2%–3%; 3 of 284 participants). Seventeen of 279 baseline isolates (6.1%; 95% CI, 3.6%–9.6%) had isoniazid monoresistance (13 of 17 had an inhA promoter mutation), but 0 of 17 had amplified resistance.

Conclusions

Treatment with standardized antituberculosis regimens dosed daily throughout, high uptake of antiretroviral therapy, and low prevalence of isoniazid monoresistance were associated with a low frequency of ADR.

Impact of HIV co-infection on the evolution and transmission of multidrug-resistant tuberculosis

The tuberculosis (TB) epidemic is fueled by a parallel Human Immunodeficiency Virus (HIV) epidemic, but it remains unclear to what extent the HIV epidemic has been a driver for drug resistance in Mycobacterium tuberculosis (Mtb). Here we assess the impact of HIV co-infection on the emergence of resistance and transmission of Mtb in the largest outbreak of multidrug-resistant TB in South America to date. By combining Bayesian evolutionary analyses and the reconstruction of transmission networks utilizing a new model optimized for TB, we find that HIV co-infection does not significantly affect the transmissibility or the mutation rate of Mtb within patients and was not associated with increased emergence of resistance within patients. Our results indicate that the HIV epidemic serves as an amplifier of TB outbreaks by providing a reservoir of susceptible hosts, but that HIV co-infection is not a direct driver for the emergence and transmission of resistant strains.

Matching AIDS and tuberculosis registry data to identify AIDS/tuberculosis comorbidity cases in California

The purpose of this study was to evaluate the sensitivity and positive predictive value (PPV) of a registry data linkage procedure used in the California AIDS and Tuberculosis (TB) Registry Data Linkage Study to identify AIDS/TB comorbidity cases in California. The California AIDS registry data from 1981 to 2006 were linked to the California TB registry data from 1996 to 2006 using LinkPlus, a probabilistic record linkage program developed by the Centers for Disease Control and Prevention, and matched results were manually reviewed to determine true or false matches. We estimated the sensitivity of this procedure to range from 98.0 per cent (95% confidence interval, CI: 97.3%, 98.7%) to 98.8 per cent (95% CI: 98.1%, 99.2%), and the PPV to be 100 per cent (95% CI: 96.8%, 100.0%). Our study demonstrated the feasibility of using this linkage procedure to match AIDS and TB registry data with a very high degree of accuracy.

Risk Factors for Acquired Rifamycin and Isoniazid Resistance: A Systematic Review and Meta-Analysis

BACKGROUND

Studies looking at acquired drug resistance (ADR) are diverse with respect to geographical distribution, HIV co-infection rates, retreatment status and programmatic factors such as regimens administered and directly observed therapy. Our objective was to examine and consolidate evidence from clinical studies of the multifactorial aetiology of acquired rifamycin and/or isoniazid resistance within the scope of a single systematic review. This is important to inform policy and identify key areas for further studies.

METHODS

Case-control and cohort studies and randomised controlled trials that reported ADR as an outcome during antitubercular treatment regimens including a rifamycin and examined the association of at least 1 risk factor were included. Post hoc, we carried out random effects Mantel-Haenszel weighted meta-analyses of the impact of 2 key risk factors 1) HIV and 2) baseline drug resistance on the binary outcome of ADR. Heterogeneity was assessed used I2 statistic. As a secondary outcome, we calculated median cumulative incidence of ADR, weighted by the sample size of the studies.

RESULTS

Meta-analysis of 15 studies showed increased risk of ADR with baseline mono- or polyresistance (RR 4.85 95% CI 3.26 to 7.23, heterogeneity I2 58%, 95% CI 26 to 76%). Meta-analysis of 8 studies showed that HIV co-infection was associated with increased risk of ADR (RR 3.02, 95% CI 1.28 to 7.11); there was considerable heterogeneity amongst these studies (I2 81%, 95% CI 64 to 90%). Non-adherence, extrapulmonary/disseminated disease and advanced immunosuppression in HIV co-infection were other risk factors noted. The weighted median cumulative incidence of acquired multi drug resistance calculated in 24 studies (assuming whole cohort as denominator, regardless of follow up DST) was 0.1% (5th to 95th percentile 0.07 to 3.2%).

CONCLUSION

Baseline drug resistance and HIV co-infection were significant risk factors for ADR. There was a trend of positive association with non-adherence which is likely to contribute to the outcome of ADR. The multifactorial aetiology of ADR in a programmatic setting should be further evaluated via appropriately designed studies.

Mycobacterium tuberculosis mutation rate estimates from different lineages predict substantial differences in the emergence of drug-resistant tuberculosis

A critical question in tuberculosis control is why some strains of Mycobacterium tuberculosis are preferentially associated with multiple drug resistances. We demonstrate that M. tuberculosis strains from Lineage 2 (East Asian lineage and Beijing sublineage) acquire drug resistances in vitro more rapidly than M. tuberculosis strains from Lineage 4 (Euro-American lineage) and that this higher rate can be attributed to a higher mutation rate. Moreover, the in vitro mutation rate correlates well with the bacterial mutation rate in humans as determined by whole genome sequencing of clinical isolates. Finally, using a stochastic mathematical model, we demonstrate that the observed differences in mutation rate predict a substantially higher probability that patients infected with a drug susceptible Lineage 2 strain will harbor multidrug resistant bacteria at the time of diagnosis. These data suggest that interventions to prevent the emergence of drug resistant tuberculosis should target bacterial as well as treatment-related risk factors.

Antituberculosis drug resistance acquired during treatment: an analysis of cases reported in California, 1994-2006

BACKGROUND

To inform efforts to prevent antituberculosis drug resistance acquired during treatment, particularly multidrug-resistant (MDR) tuberculosis, we analyzed surveillance records from the US state with the highest morbidity.

METHODS

Surveillance data from the California tuberculosis registry of cases reported between 1994 and 2006 were examined retrospectively. Crude risks of acquired resistance were estimated. Multivariate logistic regression was used to estimate odds ratios of demographic, clinical, and case management characteristics associated with acquired drug resistance (ADR), and secular trends in the incidence of ADR were assessed.

RESULTS

One in 688 patients acquired MDR tuberculosis, with crude risks varying greatly by initial drug susceptibility test results: 1 in 1909 if initially susceptible to isoniazid and rifampin, 1 in 113 if initially isoniazid resistant, and 1 in 23 if initially rifampicin resistant. Acquired isoniazid and rifampicin monoresistance occurred in 1 in 1018 and 1 in 1455 patients, respectively. Independent predictors of acquired MDR tuberculosis were initial isoniazid resistance (odds ratio [OR], 19.2; 95% confidence interval [CI], 8.25-44.7; P < .001), initial rifampicin resistance (OR, 35.9; 95% CI, 8.61-150; P < .001), human immunodeficiency virus (HIV) infection (OR, 5.07; 95% CI, 1.73-14.9; P = .003), and cavitary disease in the absence of directly observed therapy throughout therapy (OR, 2.65; 95% CI, 1.05-6.69; P = .04). The annual incidence of ADR declined over the study period.

CONCLUSIONS

Although ADR is rare and declining in California, its costly consequences warrant improvements in treatment practices. Our findings suggest that we ensure DOT throughout the course of therapy for patients with baseline drug resistance, cavitary disease, or HIV infection.

Rifampicin-monoresistant Mycobacterium tuberculosis disease among children in Cape Town, South Africa

SETTING

Tygerberg Children's Hospital (TCH) and Brooklyn Chest Hospital (BCH), South Africa.

OBJECTIVES

To describe paediatric cases of rifampicin (RMP) monoresistant tuberculosis (RMR-TB) disease.

DESIGN

Records of children with culture-confirmed RMR-TB between 1 March 2003 and 28 February 2009 were identified from a prospectively recorded database of drug-resistant TB at TCH and BCH. Mutation analysis was performed on available specimens.

RESULTS

Eighteen children with a median age of 6.9 years (range 2 months-12.8 years) were identified. Nine (50%) were human immunodeficiency virus (HIV) infected and four (22%) were HIV-exposed but non-infected. Eleven (61%) had had previous TB treatment or prophylaxis. Nine children (50%) had cavitary disease and five children (22%) had extra-pulmonary disease. Twelve (67%) had adult TB source cases, including five (42%) adults with known RMR-TB. Primary transmission occurred among 11 children (61%) and acquisition of RMR-TB was possible in seven (39%) with prior RMP exposure. Median delay to specific RMR-TB treatment was 70 days (range 23-188). One child died from RMR-TB meningitis. Gene mutations consistent with RMR-TB were confirmed in five available samples.

CONCLUSION

RMR-TB disease is increasingly encountered, particularly among HIV-infected and HIV-exposed non-infected children. Delay in commencing appropriate treatment for RMR-TB and high rates of cavitary disease could be a source of RMR-TB transmission.

Epidemiological models of Mycobacterium tuberculosis complex infections

The resurgence of tuberculosis in the 1990s and the emergence of drug-resistant tuberculosis in the first decade of the 21st century increased the importance of epidemiological models for the disease. Due to slow progression of tuberculosis, the transmission dynamics and its long-term effects can often be better observed and predicted using simulations of epidemiological models. This study provides a review of earlier study on modeling different aspects of tuberculosis dynamics. The models simulate tuberculosis transmission dynamics, treatment, drug resistance, control strategies for increasing compliance to treatment, HIV/TB co-infection, and patient groups. The models are based on various mathematical systems, such as systems of ordinary differential equations, simulation models, and Markov Chain Monte Carlo methods. The inferences from the models are justified by case studies and statistical analysis of TB patient datasets.

A mutation in Mycobacterium tuberculosis rpoB gene confers rifampin resistance in three HIV-TB cases

Rifampin is a key component of standard short-course first-line therapy against Mycobacterium tuberculosis (MTB). Rifampin monoresistant MTB, previously a rare phenomenon, is now being reported at increasing rates worldwide. We report a mutation in the rpoB region leading to low level rifampin monoresistance in a cluster of HIV-positive patients. All rifampin monoresistant isolates identified from 2004 to 2006 underwent susceptibility confirmation, sequencing of rpoB and genotyping. Three patients were found to have a previously undocumented 3 base pair insertion at codon 525 in the rpoB region. The earliest initial case was infected with fully susceptible MTB. Disease relapse occurred 7 months later with a genotypically identical MTB isolate, showing acquired rifampin monoresistance. MTB isolates from 2 subsequent patients showed primary rifampin monoresistance with an identical genotype to the index case. Patients with rifampin monoresistant MTB tend to have poorer outcomes than those with fully susceptible strains. Risk factors for the development of rifampin monoresistance include co-morbid HIV infection and previously treated tuberculosis. HIV infection has been associated with malabsorption of anti-tuberculous medications leading to sub-therapeutic levels of administered drugs. These factors may have played a role in the development of this previously undocumented mutation.

Molecular analysis of Mycobacterium tuberculosis strains with an intact pks15/1 gene in a rural community of Mexico

BACKGROUND

Mycobacterium tuberculosis (MTB) is one of the leading causes of morbidity and mortality worldwide and infects approximately 1/3 of the human population, but only 10% of all infected individuals will ever develop the disease and half of these may result in a rapid progression to disease during the first 2 years after being infected. On the other hand, some phenotypic differences among mycobacterial strains contribute to variations in the outcome of the infection, e.g., the hypervirulent phenotype described in the Beijing family has been associated with the production of a phenolic glycolipid, which reduces the production of Th1 cytokines in the experimental model and requires the activity of a polyketide synthase enzyme encoded by the pks15/1 gene.

METHODS

We analyzed clinical isolates characterized by recent transmission and rapid progression to disease to identify factors that may influence such behavior from a rural and semi-urban community in eastern Mexico.

RESULTS

Using various typing tools, we were able to identify intrafamilial clusters which belonged to the East Asian lineage of MTB isolates (Beijing family) and another that belonged to the Indo-Oceanic lineage (Manila family). All isolates within these two clusters showed an intact pks15/1 gene sequence. Additionally, we identified three more family clusters that belonged to the Euro-American lineage and showed the typical 7-bp deletion of the pks15/1 gene. This 7-bp deletion was also found in the remaining 23 cases from non-family clusters.

CONCLUSIONS

This is the first report of cases caused by strains with an intact pks15/1 gene in Mexico. Interestingly, we identified the three main mycobacterial lineages described so far: East-Asian, Indo-Oceanic, and Euro-American in a human population with almost no present-day migration.

Resistência do Mycobacterium tuberculosis às drogas em pacientes HIV+ em cinco municípios da Baixada Santista, São Paulo, Brasil

No início dos anos 90, observou-se aumento da resistência do Mycobacterium tuberculosis às drogas antituberculose, com alta prevalência entre pacientes HIV+. Neste estudo, foram avaliados a freqüência de resistência, o perfil de sensibilidade do M. tuberculosis às drogas e os fatores predisponentes à resistência entre indivíduos HIV+ nos municípios de Santos, São Vicente, Cubatão, Praia Grande e Guarujá, Estado de São Paulo, Brasil. Foram pesquisados os prontuários de 301 pacientes com resultado de cultura positivo entre 1993 e 2003. A resistência ocorreu em 57 (18,9%) pacientes com a seguinte distribuição: 32 (10,6%) apresentaram tuberculose multirresistente (resistência ao menos à Rifampicina e Isoniazida); 4 (1,3%) casos apresentaram resistência a duas ou mais drogas e 21 (7%) à monorresistência. Observou-se resistência secundária em 70,2% dos casos. Estatisticamente associadas à tuberculose resistente foram: tratamento anterior com drogas antituberculose, tempo de diagnóstico de HIV e hospitalização prévia. Em análise multivariada, apenas tratamento anterior, ajustado por faixa etária, mostrou-se associado (OR = 5,49; IC95%: 2,60-11,60). A ocorrência de resistência em 18,9% dos casos e multirresistência em aproximadamente 10% confirmam a relevância deste problema entre pacientes HIV+ na Baixada Santista.

Correlates for disease progression and prognosis during concurrent HIV/TB infection

Mycobacterium tuberculosis (Mtb) and the human immunodeficiency virus (HIV) are both life-threatening pathogens in their own right, but their synergic effects on the immune system during co-infection markedly enhance their effect on the host. This review focuses on the bidirectional interaction between HIV and Mtb and discusses the relevance of sputum smear examination, CD4+ counts, viral load at baseline and after initiation of anti-retroviral therapy, as well as additional existing and new potential immune correlates of disease progression and prognosis. These markers include beta2-microglobulin, neopterin, tumor necrosis factor receptor II (TNFRII), CD8+/CD38+, soluble urokinase plasminogen activator receptor (suPAR) and CXCL10 (or IP-10).

Serum concentrations of antimycobacterial drugs in patients with pulmonary tuberculosis in Botswana

BACKGROUND

We conducted a pharmacokinetic study of antimycobacterial drugs involving a cohort of patients with pulmonary tuberculosis (TB) in Gaborone, Botswana, to assess the prevalence of and risk factors for low drug concentrations in serum.

METHODS

Adults participated if they had a history of cough > or =2 weeks, had abnormal chest radiograph findings, consented to testing for human immunodeficiency virus (HIV), had sputum cultures positive for Mycobacterium tuberculosis, and were receiving antituberculous therapy for >7 days. Observed maximum serum concentrations were compared with published normal ranges. RESULTS. Of 91 patients enrolled, 89 (98%) were outpatients, and 59 (68%) of 87 patients tested had HIV infection. The following numbers of patients had low serum concentrations of the following drugs: isoniazid, 27 (30%) of 90; rifampin, 71 (78%) of 91; ethambutol, 37 (41%) of 91; and pyrazinamide, 1 (1%) of 91. Low serum concentrations of both isoniazid and rifampin occurred in 23 (26%) of 90 patients. Low serum concentrations of rifampin were found in both HIV-infected and non-HIV-infected patients, and such patients were less likely to have >4 weeks of symptoms, more likely to have lymphadenopathy, and more likely to have low serum albumin levels (P<.05 for all). The associations with noncavitary pulmonary disease (P=.12) and HIV infection (P=.07) did not reach statistical significance. Delayed absorption was most common with ethambutol, followed by rifampin.

CONCLUSIONS

These data, predominantly from HIV-infected patients with TB, suggest that low isoniazid, rifampin, and ethambutol concentrations are common in Botswana. In contrast, pyrazinamide usually is well absorbed.

Multidrug-resistant Mycobacterium tuberculosis in HIV-infected persons, Peru

During 1999 to 2000, we identified HIV-infected persons with new episodes of tuberculosis (TB) at 10 hospitals in Lima-Peru and a random sample of other Lima residents with TB. Multidrug-resistant (MDR)-TB was documented in 35 (43%) of 81 HIV-positive patients and 38 (3.9%)of 965 patients who were HIV-negative or of unknown HIV status (p < 0.001). HIV-positive patients with MDR-TB were concentrated at three hospitals that treat the greatest numbers of HIV-infected persons with TB. Of patients with TB, those with HIV infection differed from those without known HIV infection in having more frequent prior exposure to clinical services and more frequent previous TB therapy or prophylaxis. However, MDR-TB in HIV-infected patients was not associated with previous TB therapy or prophylaxis. MDR-TB is an ongoing problem in HIV-infected persons receiving care in public hospitals in Lima and Callao; they represent sentinel cases for a potentially larger epidemic of nosocomial MDR-TB.

Understanding tuberculosis epidemiology using structured statistical models

Molecular epidemiological studies can provide novel insights into the transmission of infectious diseases such as tuberculosis. Typically, risk factors for transmission are identified using traditional hypothesis-driven statistical methods such as logistic regression. However, limitations become apparent in these approaches as the scope of these studies expand to include additional epidemiological and bacterial genomic data. Here we examine the use of Bayesian models to analyze tuberculosis epidemiology. We begin by exploring the use of Bayesian networks (BNs) to identify the distribution of tuberculosis patient attributes (including demographic and clinical attributes). Using existing algorithms for constructing BNs from observational data, we learned a BN from data about tuberculosis patients collected in San Francisco from 1991 to 1999. We verified that the resulting probabilistic models did in fact capture known statistical relationships. Next, we examine the use of newly introduced methods for representing and automatically constructing probabilistic models in structured domains. We use statistical relational models (SRMs) to model distributions over relational domains. SRMs are ideally suited to richly structured epidemiological data. We use a data-driven method to construct a statistical relational model directly from data stored in a relational database. The resulting model reveals the relationships between variables in the data and describes their distribution. We applied this procedure to the data on tuberculosis patients in San Francisco from 1991 to 1999, their Mycobacterium tuberculosis strains, and data on contact investigations. The resulting statistical relational model corroborated previously reported findings and revealed several novel associations. These models illustrate the potential for this approach to reveal relationships within richly structured data that may not be apparent using conventional statistical approaches. We show that Bayesian methods, in particular statistical relational models, are an important tool for understanding infectious disease epidemiology.

Tuberculosis and HIV: a partnership against the most vulnerable

Tuberculosis (TB) is a major cause of morbidity and mortality worldwide. Each year, there are eight million new Mycobacterium tuberculosis complex (MTB) infections and three million TB-related deaths. The catastrophic effects of TB are borne disproportionately among the most vulnerable. The HIV pandemic has further increased the burden so that the risk of TB reactivation from latency is 5 to 15 percent in HIV/TB coinfection. Tuberculosis reactivation fuels further primary infections, creating a vicious cycle of increasing infection, disease, and deaths. In addition, drug-resistant TB exacerbates this increasingly common problem. The clinical presentations of TB in relation to HIV and HIV-associated immune deficiency are discussed from the perspective of clinical diagnosis and treatment in patient care. Tuberculosis prophylaxis, concurrent drug treatment of TB and HIV, drug interactions, and overlapping toxicities are detailed for the practitioner. Immune reconstitution inflammatory reactions are now a common phenomenon in HIV treatment, where similar reactions have been less commonly described in TB treatment in the past. Global distributive injustices in wealth, the burden of disease, and the provision of healthcare are obvious in TB, and clearly show us that the needs of the most vulnerable populations must be met in order to address the problems.

Malabsorption of rifampin and isoniazid in HIV-infected patients with and without tuberculosis

The absorption of rifampin, isoniazid, and D-xylose in patients with human immunodeficiency virus (HIV) infection and diarrhea, in patients with HIV infection and tuberculosis (TB), in patients with pulmonary TB alone, and in healthy subjects was studied. Percentage of dose of the drugs, their metabolites, and D-xylose excreted in urine were calculated. A significant reduction in the absorption of drugs and D-xylose in both the HIV infection/diarrhea and HIV infection/TB groups was observed (P<.05), and the correlation between them was significant. Our results indicate that patients with HIV infection and diarrhea and those with HIV infection and TB have malabsorption of rifampin and isoniazid.

Fatores associados aos tratamentos inadequados em grupo de portadores de tuberculose multirresistente

INTRODUÇÃO: A tuberculose multirresistente é uma ameaça ao controle da tuberculose em todo o mundo. Tratamento inadequado é freqüentemente apontado como fator de risco para tuberculose multirresistente. OBJETIVO: Identificar fatores associados ao tratamento inadequado em portadores de tuberculose multirresistente. MÉTODO: Foram levantados e identificados os testes de sensibilidade para tuberculose, realizados no Laboratório Central do Estado do Ceará de 1990 a 1999. Foi realizado um estudo retrospectivo e prospectivo, em grupo de portadores de tuberculose multirresistente, comparando as características dos pacientes com tratamento adequado com as dos com tratamentos inadequados. Foi considerado multirresistente o bacilo resistente a pelo menos rifampicina + isoniazida e utilizado o método das proporções. RESULTADOS: Dos 1.500 testes de sensibilidade realizados, 266 eram multirresistentes. Destes, identificaram-se apenas 153 pacientes, dos quais 19 foram excluídos, restando, no estudo, 134 pacientes. Pela análise univariada os fatores associados significativamente ao tratamento inadequado foram: não-adesão ao tratamento, pobreza extrema, intolerância medicamentosa, falha no atendimento, falta de medicação, dois ou mais tratamentos anteriores, lesões radiológicas bilaterais e grandes cavidades pulmonares. Foi encontrada ainda associação (p < 0,001) de alcoolismo e/ou tabagismo com a não-adesão. Na análise multivariada, permaneceram associados ao tratamento inadequado: dois ou mais tratamentos anteriores (p < 0,0001, OR = 5,9; IC 95%: 2,5-13,7), grandes cavidades pulmonares (p < 0,0217, OR = 2,7; IC 95%: 1,2-6,1) e lesões radiológicas bilaterais (p < 0,0226, OR = 3,2; IC 95%: 1,4-7,4). CONCLUSÃO: Neste estudo, observou-se que os fatores associados aos tratamentos inadequados são de grande abrangência. Deve existir uma tentativa para controlar melhor a doença, principalmente nos pacientes em retratamento e nos portadores de grandes cavidades e/ou lesões bilaterais na radiografia torácica.

Fluoroquinolones, tuberculosis, and resistance

Although the fluoroquinolones are presently used to treat tuberculosis primarily in cases involving resistance or intolerance to first-line antituberculosis therapy, these drugs are potential first-line agents and are under study for this indication. However, there is concern about the development of fluoroquinolone resistance in Mycobacterium tuberculosis, particularly when administered as monotherapy or as the only active agent in a failing multidrug regimen. Treatment failures as well as relapses have been documented under such conditions. With increasing numbers of fluoroquinolone prescriptions and the expanded use of these broad-spectrum agents for many infections, the selective pressure of fluoroquinolone use results in the ready emergence of fluoroquinolone resistance in a diversity of organisms, including M tuberculosis. Among M tuberculosis, resistance is emerging and may herald a significant future threat to the long-term clinical utility of fluoroquinolones. Discussion and education regarding appropriate use are necessary to preserve the effectiveness of this antibiotic class against the hazard of growing resistance.

Managing antituberculosis drug therapy by therapeutic drug monitoring of rifampicin and isoniazid

BACKGROUND

Current therapeutic regimens with rifampicin and isoniazid have proven successful in treating tuberculosis, however, toxicity, therapeutic failure, relapse and multiple drug resistance are serious concerns. Optimizing drug dose using therapeutic drug monitoring (TDM) may be a better approach than administering therapy as a standard dose.

AIMS

To establish and evaluate a TDM service to optimize rifampicin and isoniazid therapy.

METHODS

A TDM service for rifampicin and isoniazid was established in November 1998. Drug concentration data were collected, with relevant information to interpret the results. The reason for the request, information on concomitant drug administration and a questionnaire to assess clinical response to the drug results were also obtained.

RESULTS

Ninety patient episodes were accepted for study. The rifampicin plasma concentrations showed significant scatter, with 46% of the rifampicin concentrations below the normal range and 2% above the normal range. Similarly, 48% of isoniazid concentrations were below the lower target of the normal range and 29% were above the upper normal limit. There was a greater proportion of isoniazid concentrations above the normal range in female patients.

CONCLUSION

Significant pharmacokinetic variability was observed for rifampicin and isoniazid in the patient population studied. Further, a substantial number of plasma concentrations fell outside the suggested normal range for both drugs. Isoniazid plasma concentrations were significantly higher in female patients compared with male patients. Despite these abnormal results, the dose of rifampicin and isoniazid was altered in only 17% of patients, however, many patients received follow-up education because of the drug result. The service was considered valuable by 83% of respondents to the questionnaire. While TDM of rifampicin and isoniazid is a valuable tool to optimize the dose of these drugs in some patients, there is an urgent need for concentration-effect studies and possibly education on the principles and practice of TDM for these drugs.

Antimycobacterial pimarane diterpenes from the Fungus Diaporthe sp

Two new pimarane diterpenes, diaportheins A (1) and B (2), were isolated from a culture broth of the fungus Diaporthe sp. BCC 6140. Diaporthein B (2) strongly inhibited the growth of Mycobacterium tuberculosis with the MIC value of 3.1 microg/mL, while diaporthein A (1) showed only mild activity (MIC value of 200 microg/mL).

Hirsutellide A, a new antimycobacterial cyclohexadepsipeptide from the entomopathogenic fungus Hirsutella kobayasii

A new cyclohexadepsipeptide, named hirsutellide A (1), was isolated from a cell extract of the entomopathogenic fungus Hirsutella kobayasii BCC 1660. The structure of 1 was elucidated by analyses of spectroscopic data, and its absolute stereochemistry was addressed by the use of Marfey's method. Hirsutellide A (1) exhibited antimycobacterial and antimalarial activities, but was inactive toward the Vero cell line (at 50 microg/mL).

Molecular detection of early appearance of drug resistance during Mycobacterium tuberculosis infection

During the early development of drug resistance in Mycobacterium tuberculosis (M. tuberculosis) infection only a small proportion of resistant bacteria are present within a milieu of sensitive bacteria. This complicates the use of molecular methods to predict the presence of a resistant phenotype and has been largely ignored in many of the newly developed molecular methods. In this study, mixtures of DNA from M. tuberculosis strains with known wild-type and mutant sequences were used to evaluate the sensitivity of three different molecular methods for detection of drug resistance. The dot-blot and amplification refractory mutation system (ARMS) methods showed sensitivities that approach those of routine phenotypic methods and are able to detect the presence of mutant sequences at a ratio of 1 in 50 (corresponding to 2% mutant sequences). This is 10-fold more sensitive than the commercial kit. The ARMS method was also used to investigate the use of molecular methods to identify mixed infections, and both drug-resistant and susceptible strain populations were identified in a single clinical isolate. These findings highlight the applicability of molecular methods to the rapid detection of drug resistance in tuberculosis patients, particularly in those who are non-compliant and in contacts of known drug-resistant tuberculosis patients, and assistance in limiting the spread of drug-resistant strains.

Sensitivity to anti-tuberculosis drugs in HIV-positive and -negative patients in Addis Ababa

A cross-sectional survey was conducted between 1 August and 31 December, 1998 in Addis Ababa, Ethiopia to determine the rate of primary drug resistance to anti-tuberculosis drugs and to investigate its possible association with HIV infection. Sputum culture, sensitivity to first-line anti-tuberculosis drugs and HIV testing were done for 236 sputum smear-positive pulmonary tuberculosis patients. Primary drug resistance level (single or multidrug resistance) had not changed significantly since 1994. Primary resistance occurred more often among HIV-positive than among HIV-negative patients. The association between drug resistance and HIV will have a serious impact in the control of tuberculosis because in recent years the prevalence of HIV has increased dramatically in Ethiopia. Therefore, further studies on drug resistance and HIV infection and the establishment of drug resistance surveillance are recommended.

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.

Discriminatory public policies and the New York City tuberculosis epidemic, 1975-1993

Discriminatory public policies removed over ten percent of the fire companies in New York City from 1972-1975, mainly from poor communities of color with very old multiple-dwellings. Hundreds of thousands of housing units were destroyed between 1972 and 1978. Patterns of housing overcrowding changed rapidly and social networks were broken. Tuberculosis went into obvious epidemic in 1979. The temporal and geographic dynamics of the TB epidemic is described here as are the lessons for Europe with respect to treatment of marginalized populations.

Predictors of tuberculosis transmission in prisons: an analysis using conventional and molecular methods

OBJECTIVE

To determine the tuberculosis (TB) transmission patterns within the prison system in Catalonia, conventional epidemiological techniques were combined with DNA fingerprinting of Mycobacterium tuberculosis.

METHODS

IS6110- and polymorphic GC-rich repeat sequence (PGRS)-based restriction fragment length polymorphism (RFLP) were combined with epidemiological studies to assess the relatedness of isolates from all patients with confirmed TB at five prisons in the province of Barcelona (Catalonia, Spain), between 1 July 1994 and 31 December 1996. Risk factors for transmission were analysed to a logistic regression. The extent of drug-resistant TB was also assessed.

RESULTS

The incidence of TB during the study period was 2775 cases per 100,000 inmate years. Of the 247 culture-positive cases, 126 (51%) appeared to have active TB as a result of recent transmission. Using conventional epidemiological methods, 14 active chains of transmission were identified in prison involving 65 isolates (52% of clustered patients). A lengthy history of imprisonment [odds ratio (OR) 2.8, 95% confidence interval (CI) 1.52-5.11] and pulmonary TB (OR 2.36, 95% CI 1.17-4.75) were independently associated with clustering. Low rates of both initial (2.9%) and acquired drug resistance (5.8%) were identified and there was no evidence of the transmission of drug-resistant TB.

CONCLUSION

In the prison system studied, the recent transmission of TB contributes substantially to the overall incidence of the disease. Both lengthy incarcerations and delays in identifying inmates with pulmonary symptoms play a key role in this recent transmission. Directly observed therapy (DOT) is a critical control strategy for reducing the emergence of drug resistance and for avoiding the transmission of resistant organisms.

Medication monitors to treat tuberculosis. A supplement to directly observed therapy

The use of directly observed therapy (DOT) for nearly all cases of pulmonary tuberculosis (TB) is being widely promoted by the Centers for Disease Control, but its implementation is being resisted by many health professionals. Consequently, less than half of the patients in major metropolitan health departments were given DOT in 1996. The usual justification for "universal" DOT instead of selective DOT is the well-known difficulty in differentiating between patients who are reliable in taking medication from those who are not. Devices called medication monitors, which record when medication is removed from a container, were shown to be effective in determining the reliability of TB patients in taking medication in the 1960s but were cumbersome to use. Since then several improved, convenient to use, electronic medication monitors have been introduced and further improvements can be anticipated. These increasingly practical medication monitors need to be studied as a supplement to DOT in order to make selective DOT an effective alternative to "universal" DOT in managing the medication compliance problem when treating TB.

Pathogens, old and new: an update for cardiovascular nurses

Infectious diseases remain the major cause of death throughout the world, and this is not likely to change in the foreseeable future. However, there are steps that can be taken to combat them, including both the recognition of and interventions against emerging infectious diseases. This article will provide general information about emerging infectious organisms, mechanisms of resistance to antimicrobial agents, and comments on a variety of prevention strategies. In addition, the reader is directed to a number of comprehensive references for additional information.

Cross-matching TB and AIDS registries: TB patients with HIV co-infection, United States, 1993-1994

OBJECTIVES

Because of limited reporting of HIV status in case reports to the national tuberculosis (TB) surveillance system, the authors conducted this study to estimate the proportion of US TB cases with HIV co-infection and to describe demographic and clinical characteristics of co-infected patients.

METHODS

The 50 states, New York City, and Puerto Rico submitted the results of cross-matches of TB registries and HIV-AIDS registries. The authors determined the number of TB cases reported for 1993-1994 that were listed in HIV-AIDS registries and analyzed data on demographic and clinical characteristics by match status.

RESULTS

Of 49,938 TB cases reported for 1993-1994, 6863 (14%) were listed in AIDS or HIV registries. The proportions of TB-AIDS cases among TB cases varied by reporting area, from 0% to 31%. Anti-TB drug resistance was higher among TB-AIDS cases, particularly resistance to isoniazid and rifampin (multidrug resistance) and rifampin alone, In some areas with low proportions of multidrug-resistant TB cases, however, the difference in multidrug resistance between TB-AIDS patients and non-AIDS TB patients was not found.

CONCLUSIONS

The proportion of TB cases with HIV co-infection, particularly in some areas, underscores the importance of the HIV-AIDS epidemic for the epidemiology of TB. Efforts to improve HIV testing as well as reporting of HIV status for TB patients should continue to ensure optimum management of coinfected patients, enhance surveillance activities, and promote judicious resource allocation and targeted prevention and control activities.