Nosocomial transmission of Mycobacterium bovis resistant to 11 drugs in people with advanced HIV-1 infection

Síndrome de Wiskott-Aldrich en España: incidencia, mortalidad y sesgo de género durante 21 años

Antecedentes

El síndrome de Wiskott-Aldrich (SWA) es un raro trastorno ligado al cromosoma X que se considera que afecta predominantemente a varones.

Objetivo

El objetivo de este estudio consistía en investigar la incidencia y la mortalidad intrahospitalaria del SWA en España, así como el sesgo de género.

Métodos

Se llevó a cabo un estudio epidemiológico retrospectivo poblacional en 97 pacientes con SWA diagnosticados en hospitales españoles entre 1997 y 2017, utilizando para ello datos del Sistema Nacional de Vigilancia de Datos Hospitalarios.

Resultados

Nuestros resultados revelaron que la incidencia anual media del SAW en España fue de 1,1 caso por cada 10 millones de habitantes (IC del 95 %, 0,45-2,33). El riesgo relativo fue mayor en los varones que en las mujeres (2,42). El diagnóstico de SWA se establece a una edad más avanzada en las mujeres (mediana de 47 años) que en los varones (mediana de 5,5 años). Únicamente los varones ingresaron en el hospital en al menos 10 ocasiones diferentes y todas las muertes se detectaron en varones. La tasa de mortalidad intrahospitalaria fue del 9,28 % en el SAW y la mayoría de las muertes se asociaron a hemorragia cerebral o infección.

Conclusiones

El SWA, una enfermedad rara, se diagnostica a una edad más avanzada en las mujeres y la mortalidad se observó exclusivamente en varones, asociada en la mayoría de los casos a hemorragia cerebral e infección.

A case report of transmission and disease caused by Mycobacterium caprae and Mycobacterium bovis in Lima, Peru

BACKGROUND

The Tuberculosis (TB) burden in Peru is significant with respect to both disease morbidity and mortality. Furthermore the recent diversification of farming enterprise to include a wide range of animal species has necessitated the consideration of members of the Mycobacterium Tuberculosis Complex (MTBC) with the potential for zoonotic transmission. M. bovis and M. caprae, a lesser known member of the MTBC exhibit an exceptionally wide host spectrum in animals and are capable of causing disease in humans. M. bovis has a predictable resistance profile which includes resistance to pyrazinamide. Thus, failure to identify M. bovis as the causative agent in reported TB cases leads to higher levels of treatment failure and contributes to the transmission of drug-resistant TB.

CASE PRESENTATION

Reported here are the clinical presentations, investigations and treatment histories of two patients identified from a population level genotyping study in Lima, Peru that were at the time of treatment thought to be M. tuberculosis patients but in retrospect were spectated using whole genome sequencing as M. caprae and M. Bovis.

CONCLUSIONS

The cases reported here constitute convincing evidence that M. caprae and M. bovis are causative agents of TB infection in humans in Peru and underscore the importance of species-level MTBC member identification to effectively control and treat zoonotic TB. Furthermore these cases highlight the challenges of using clinical risk factors to identify cases of zoonotic TB in humans as their clinical presentation and transmission history is often difficult to distinguish from anthroponotic TB.

Zoonotic Tuberculosis in Humans: Control, Surveillance, and the One Health Approach

Zoonotic tuberculosis is a reemerging infectious disease in high-income countries and a neglected one in low- and middle-income countries. Despite major advances in its control as a result of milk pasteurization, its global burden is unknown, especially due the lack of surveillance data. Additionally, very little is known about control strategies. The purpose of this review was to contextualize the current knowledge about the epidemiology of zoonotic tuberculosis and to describe the available evidence regarding surveillance and control strategies in high-, middle-, and low-income countries. We conducted this review enriched by a One Health perspective, encompassing its inherent multifaceted characteristics. We found that the burden of zoonotic tuberculosis is likely to be underreported worldwide, with higher incidence in low-income countries, where the surveillance systems are even more fragile. Together with the lack of specific political commitment, surveillance data is affected by lack of a case definition and limitations of diagnostic methods. Control measures were dependent on risk factors and varied greatly between countries. This review supports the claim that a One Health approach is the most valuable concept to build capable surveillance systems, resulting in effective control measures. The disease characteristics and suggestions to implement surveillance and control programs are discussed.

Detection of a streptomycin-resistant Mycobacterium bovis strain through antitubercular drug susceptibility testing of Tunisian Mycobacterium tuberculosis complex isolates from cattle

Background

A rising isolation trend of drug-resistant M. bovis from human clinical cases is documented in the literature. Here we assessed Mycobacterium tuberculosis complex isolates from cattle for drug susceptibility by the gold standard agar proportion method and a simplified resazurin microtitre assay (d-REMA). A total of 38 M. tuberculosis complex strains, including M. bovis (n = 36) and M. caprae (n = 2) isolates, from cattle in Tunisia were tested against isoniazid, rifampin, streptomycin, ethambutol, kanamycin and pyrazinamide.

Results

M. caprae isolates were found to be susceptible to all test drugs. All M. bovis strains were resistant to pyrazinamide, as expected. In addition, one M. bovis isolate showed high-level resistance to streptomycin (MIC > 500.0 μg/ml). Concordant results with the two methods were found. The most common target genes associated with streptomycin resistance, namely the rrs, rpsL and gidB genes, were DNA sequenced. A non-synonymous mutation at codon 43 (K43R) was found in the rpsL gene. To the best of our knowledge, this is the first report describing the isolation of a streptomycin-resistant M. bovis isolate from animal origin.

Conclusions

Antitubercular drug susceptibility testing of M. bovis isolates from animals should be performed in settings where bTB is endemic in order to estimate the magnitude of the risk of drug-resistant tuberculosis transmission to humans.

AIDS Clinical Research in Spain-Large HIV Population, Geniality of Doctors, and Missing Opportunities

The first cases of AIDS in Spain were reported in 1982. Since then over 85,000 persons with AIDS have been cumulated, with 60,000 deaths. Current estimates for people living with HIV are of 145,000, of whom 20% are unaware of it. This explains the still high rate of late HIV presenters. Although the HIV epidemic in Spain was originally driven mostly by injection drug users, since the year 2000 men having sex with men (MSM) account for most new incident HIV cases. Currently, MSM represent over 80% of new yearly HIV diagnoses. In the 80s, a subset of young doctors and nurses working at Internal Medicine hospital wards became deeply engaged in attending HIV-infected persons. Before the introduction of antiretrovirals in the earlier 1990s, diagnosis and treatment of opportunistic infections was their major task. A new wave of infectious diseases specialists was born. Following the wide introduction of triple combination therapy in the late 1990s, drug side effects and antiretroviral resistance led to built a core of highly devoted HIV specialists across the country. Since then, HIV medicine has improved and currently is largely conducted by multidisciplinary teams of health care providers working at hospital-based outclinics, where HIV-positive persons are generally seen every six months. Antiretroviral therapy is currently prescribed to roughly 75,000 persons, almost all attended at clinics belonging to the government health public system. Overall, the impact of HIV/AIDS publications by Spanish teams is the third most important in Europe. HIV research in Spain has classically been funded mostly by national and European public agencies along with pharma companies. Chronologically, some of the major contributions of Spanish HIV research are being in the field of tuberculosis, toxoplasmosis, leishmaniasis, HIV variants including HIV-2, drug resistance, pharmacology, antiretroviral drug-related toxicities, coinfection with viral hepatitis, design and participation in clinical trials with antiretrovirals, immunopathogenesis, ageing, and vaccine development.

Mycobacterium tuberculosis genotypes and predominant clones among the multidrug-resistant isolates in Spain 1998-2005

Although the incidence of tuberculosis (TB) is gradually decreasing in Spain, there is an increase in the proportion of foreign-born cases. This changing scenario is slowly shifting the local TB epidemiology from endemic to imported cases with an increased risk for multidrug-resistant (MDR) and extensively drug resistant (XDR) strains of Mycobacterium tuberculosis complex. MDR/XDR strains from Spain (n=366 MTBC isolates, 1 strain per patient) isolated between 1998 and 2005 were retained for this retrospective analysis. All strains were analyzed by spoligotyping, while 12-loci MIRU-VNTR data were available for 106 isolates from 2003 to 2005. Demographic, phylogenetic, and epidemiologic analyses using anonymized data were collected and analyzed using the SITVIT2 database. Our study provides with a first snapshot of genetic diversity of MDR/XDR-TB in several autonomous regions of Spain. It highlights significantly more of SIT1/Beijing and SIT66/BOV MDR isolates (5.7% and 7.38% respectively) and increasingly more foreign-born cases from Eastern Europe. Future studies should focus on shared genotypes between Spanish and foreign-born patients to decipher the modes of transmission and risk factors involved, and decipher the proportion of imported cases of active disease versus cases of reactivation of latent TB infection among foreign-born individuals.

Assessment of listing and categorisation of animal diseases within the framework of the Animal Health Law (Regulation (EU) No 2016/429): bovine tuberculosis

Bovine tuberculosis has been assessed according to the criteria of the Animal Health Law (AHL), in particular criteria of Article 7 on disease profile and impacts, Article 5 on the eligibility of bovine tuberculosis to be listed, Article 9 for the categorisation of bovine tuberculosis according to disease prevention and control rules as in Annex IV and Article 8 on the list of animal species related to bovine tuberculosis. The assessment has been performed following a methodology composed of information collection and compilation, expert judgement on each criterion at individual and, if no consensus was reached before, also at collective level. The output is composed of the categorical answer, and for the questions where no consensus was reached, the different supporting views are reported. Details on the methodology used for this assessment are explained in a separate opinion. According to the assessment performed, bovine tuberculosis can be considered eligible to be listed for Union intervention as laid down in Article 5(3) of the AHL. The disease would comply with the criteria as in Sections 2, 3, 4 and 5 of Annex IV of the AHL, for the application of the disease prevention and control rules referred to in points (b), (c), (d) and (e) of Article 9(1). The main animal species to be listed for bovine tuberculosis according to Article 8(3) criteria are several mammal species, as indicated in the present opinion.

The changing epidemiology of tuberculosis in a Spanish tertiary hospital (1995-2013)

Important epidemiological changes and improvement of new diagnostic approaches, mainly molecular tools, might have impacted the management and outcome of tuberculosis (TB) in the last years in industrialized countries. In order to describe the epidemiological trends, and changes in clinical, diagnostic, and therapeutic aspects in patients with TB, an observational study was performed in a tertiary hospital in Western Europe (Madrid, Spain).All adult patients (>16 years) with a diagnosis of TB in the period 1995 to 2013 were included in the study.TB was diagnosed in 1284 patients, including 304 (24%) foreign-born and 298 (23.2%) human immunodeficiency virus (HIV)-infected patients. The proportion of foreign-born patients increased significantly, from 7.4% (1995) to 40.3% (2013), P < .001, while the proportion of patients with HIV infection decreased (from 41% to 15%, P < .001). Extrapulmonary locations of TB increased (from 23.9% to 37.1%, P < .001), although the miliary forms were less frequent (from 16% to 5.6%, P < .001). Pulmonary involvement remained constant during the period of study (from 50% to 46%, P = .18). The yield of microbiological diagnostic methods in different clinical specimens has remained very similar. Only molecular techniques have improved the diagnosis in respiratory, urinary, and peritoneal samples. The global cure rate was 64.8% and mortality rate was 9.1% (6.5% directly attributable to TB). Mortality has decreased significantly during the years of study (from 11% to 2%, P < .001).There has been a significant decline in the number of patients with TB. Changes in HIV coinfection and immigration have conditioned other epidemiological and clinical aspects of the disease, including the clinical presentation, treatment response, and mortality. Only the use of molecular tests has provided an improvement in the diagnosis of pulmonary and extrapulmonary TB.

Human tuberculosis caused by Mycobacterium bovis: a retrospective comparison with Mycobacterium tuberculosis in a Mexican tertiary care centre, 2000-2015

Background

Human tuberculosis caused by Mycobacterium bovis is believed to be frequent in developing countries. Transmission is usually through ingestion of unpasteurized dairy products, although airborne contagion is possible. Disease caused by M. tuberculosis or M. bovis is clinically indistinguishable from each other. The aim of this study was to determine the factors associated with M. bovis disease.

Methods

Retrospective analysis of all culture-positive cases of M. bovis and M. tuberculosis from 2000 to 2015, in a Mexican tertiary-care centre. Sociodemographic, clinical, and radiographic data from medical records were compared. Disease site was classified as pulmonary, extrapulmonary, or pulmonary and extrapulmonary, based on cultures.

Results

We evaluated 533 cases, 372 (69.7 %) of which were caused by M. tuberculosis and 161 (30.2 %) by M. bovis. Characteristics associated with M. bovis disease were: younger age (aOR 0.97, 95 % CI 0.95–0.98), glucocorticoid use (aOR 2.27, 95 % CI 1.42–3.63), and extrapulmonary disease (aOR 1.80, 95 % CI 1.21–2.69). M. tuberculosis was associated with lower socioeconomic status (aOR 0.52, 95 % CI 0.28–0.97). When we analysed only pulmonary cases, younger age (aOR 0.97, 95 % CI 0.96–0.99), glucocorticoid use (aOR 2.41, 95 % CI 1.30–4.46), and smoking (aOR 1.94, CI 95 % 1.15–3.27) were associated with M. bovis. Both groups showed similar proportions of direct microscopy smear results (respiratory samples) and chest X-ray cavitations.

Conclusions

Younger age, glucocorticoid use, and extrapulmonary disease were associated with M. bovis as the causative agent of tuberculosis in a group of patients from a tertiary care centre in a country where bovine tuberculosis is endemic. Further studies must be conducted in the general population to determine pathogen-specific associated factors and outcomes.

Trends of Mycobacterium bovis Isolation and First-Line Anti-tuberculosis Drug Susceptibility Profile: A Fifteen-Year Laboratory-Based Surveillance

BACKGROUND

Mycobacterium tuberculosis causes the majority of tuberculosis (TB) cases in humans; however, in developing countries, human TB caused by M. bovis may be frequent but undetected. Human TB caused by M. bovis is considered a zoonosis; transmission is mainly through consumption of unpasteurized dairy products, and it is less frequently attributed to animal-to-human or human-to-human contact. We describe the trends of M. bovis isolation from human samples and first-line drug susceptibility during a 15-year period in a referral laboratory located in a tertiary care hospital in Mexico City.

METHODOLOGY/PRINCIPAL FINDINGS

Data on mycobacterial isolates from human clinical samples were retrieved from the laboratory's database for the 2000-2014 period. Susceptibility to first-line drugs: rifampin, isoniazid, streptomycin (STR) and ethambutol was determined. We identified 1,165 isolates, 73.7% were M. tuberculosis and 26.2%, M. bovis. Among pulmonary samples, 16.6% were M. bovis. The proportion of M. bovis isolates significantly increased from 7.8% in 2000 to 28.4% in 2014 (X(2)trend, p<0.001). Primary STR resistance was higher among M. bovis compared with M. tuberculosis isolates (10.9% vs.3.4%, p<0.001). Secondary multidrug resistance (MDR) rates were 38.5% and 34.4% for M. bovis and M. tuberculosis, respectively (p = 0.637). A rising trend of primary STR monoresistance was observed for both species (3.4% in 2000-2004 vs. 7.6% in 2010-2014; p = 0.02).

CONCLUSIONS/SIGNIFICANCE

There is a high prevalence and a rising trend of M. bovis isolates in our region. The proportion of pulmonary M. bovis isolates is higher than in previous reports. Additionally, we report high rates of primary anti-tuberculosis resistance and secondary MDR in both M. tuberculosis and M. bovis. This is one of the largest reports on drug susceptibility of M. bovis from human samples and shows a significant proportion of first-line anti-tuberculosis drug resistance.

[Epidemiology of hospitalizations for tuberculosis in Spain: analysis of minimum data set 1999-2009]

INTRODUCTION

The National Hospital Discharge Registry is a clinical-administrative database on hospital discharges, which is very useful at a regional level as a complementary source for surveillance. There are few national studies on tuberculosis (TB) using the National Hospital Discharge Registry, thus it was considered of interest to study the characteristics and trends of hospital discharges for TB in Spain.

METHODS

A descriptive study was performed using the main variables in the National Hospital Discharge Registry (sex, age, main diagnosis, type of discharge, length of stay), and trend analysis of hospitalization rates per 100,000 population, as well as primary diagnosis, by sex, age group, and type of TB (pulmonary [TBP]/extrapulmonary [TBEP]), for the period 1999-2009 in Spain.

RESULTS

A total of 65,609 hospital discharges were included in the study (66% male, 66% TBP, and 52% between 15-44 years). The overall rate of TB for the entire hospitalization period was 13.93 per 100,000 inhabitants, being 18.83 in males and 9.18 in females. The hospitalization rates for TBP and TBEP decreased in the period 1999-2009 in both sexes (TBP in males, from 18 to 13, and in females, from 8 to 6; TBEP in males from 4 to 3, and from 3 to 2 in female hospitalizations/100,000 habitants). In TBP, children are those with a smallest decline, and in TBEP there is an increase in males in all age groups from 2005.

CONCLUSIONS

The results are consistent with those from surveillance. The slow decline in rates in children and the increase in extrapulmonary forms in males may be related to immigration, so it is necessary to improve TB monitoring in these groups.

Current knowledge and pending challenges in zoonosis caused by Mycobacterium bovis: a review

Mycobacterium bovis is both the causative agent of bovine tuberculosis (TB) and a zoonotic pathogen. In humans, considerably fewer cases of TB are caused by M. bovis than M. tuberculosis; nevertheless, diagnostic limitations mean that currently available data on prevalence grossly underestimate the true dimension of the problem. The routes of transmission from animals to humans are well known and include direct exposure to infected animals or consumption of contaminated animal products. Application of fingerprinting tools facilitates analysis of the molecular epidemiology of M. bovis in animal-to-human and human-to-human transmission. Apart from cattle and M. bovis, other animal species and members within the M. tuberculosis complex can contribute to the zoonosis. Improvements in diagnostic techniques, application of more advanced discriminatory genotyping tools, and collaboration between veterinary and human health care researchers are key to our understanding of this zoonosis.

The re-emergence of tuberculosis: what have we learnt from molecular epidemiology?

Tuberculosis (TB) has re-emerged over the past two decades: in industrialized countries in association with immigration, and in Africa owing to the human immunodeficiency virus epidemic. Drug-resistant TB is a major threat worldwide. The variable and uncertain impact of TB control necessitates not only better tools (diagnostics, drugs, and vaccines), but also better insights into the natural history and epidemiology of TB. Molecular epidemiological studies over the last two decades have contributed to such insights by answering long-standing questions, such as the proportion of cases attributable to recent transmission, risk factors for recent transmission, the occurrence of multiple Mycobacterium tuberculosis infection, and the proportion of recurrent TB cases attributable to re-infection. M. tuberculosis lineages have been identified and shown to be associated with geographical origin. The Beijing genotype is strongly associated with multidrug resistance, and may have escaped from bacille Calmette-Guérin-induced immunity. DNA fingerprinting has quantified the importance of institutional transmission and laboratory cross-contamination, and has helped to focus contact investigations. Questions to be answered in the near future with whole genome sequencing include identification of chains of transmission within clusters of patients, more precise quantification of mixed infection, and transmission probabilities and rates of progression from infection to disease of various M. tuberculosis lineages, as well as possible variations in vaccine efficacy by lineage. Perhaps most importantly, dynamics in the population structure of M. tuberculosis in response to control measures in high-prevalence areas should be better understood.

Population estimation and trappability of the European badger (Meles meles): implications for tuberculosis management

Estimates of population size and trappability inform vaccine efficacy modelling and are required for adaptive management during prolonged wildlife vaccination campaigns. We present an analysis of mark-recapture data from a badger vaccine (Bacille Calmette–Guérin) study in Ireland. This study is the largest scale (755 km²) mark-recapture study ever undertaken with this species. The study area was divided into three approximately equal–sized zones, each with similar survey and capture effort. A mean badger population size of 671 (SD: 76) was estimated using a closed-subpopulation model (CSpM) based on data from capturing sessions of the entire area and was consistent with a separate multiplicative model. Minimum number alive estimates calculated from the same data were on average 49–51% smaller than the CSpM estimates, but these are considered severely negatively biased when trappability is low. Population densities derived from the CSpM estimates were 0.82–1.06 badgers km⁻², and broadly consistent with previous reports for an adjacent area. Mean trappability was estimated to be 34–35% per session across the population. By the fifth capture session, 79% of the adult badgers caught had been marked previously. Multivariable modelling suggested significant differences in badger trappability depending on zone, season and age-class. There were more putatively trap-wary badgers identified in the population than trap-happy badgers, but wariness was not related to individual’s sex, zone or season of capture. Live-trapping efficacy can vary significantly amongst sites, seasons, age, or personality, hence monitoring of trappability is recommended as part of an adaptive management regime during large–scale wildlife vaccination programs to counter biases and to improve efficiencies.

Bovine tuberculosis at the human-livestock-wildlife interface: is it a public health problem in Tanzania? A review

Despite the apparent public health concern about Bovine tuberculosis (BTB) in Tanzania, little has been done regarding the zoonotic importance of the disease and raising awareness of the community to prevent the disease. Bovine tuberculosis is a potential zoonotic disease that can infect a variety of hosts, including humans. The presence of multiple hosts including wild animals, inefficient diagnostic techniques, absence of defined national controls and eradication programs could impede the control of bovine TB. In Tanzania, the diagnosis of Mycobacterium bovis in animals is mostly carried out by tuberculin skin testing, meat inspection in abattoirs and only rarely using bacteriological techniques. The estimated prevalence of BTB in animals in Tanzania varies and ranges across regions from 0.2% to 13.3%, which is likely to be an underestimate if not confirmed by bacteriology or molecular techniques. Mycobacterium bovis has been detected and isolated from different animal species and has been recovered in 10% of apparently healthy wildebeest that did not show lesions at post-mortem. The transmission of the disease from animals to humans can occur directly through the aerosol route and indirectly by consumption of raw milk. This poses an emerging disease threat in the current era of HIV confection in Tanzania and elsewhere. Mycobacterium bovis is one of the causative agents of human extra pulmonary tuberculosis. In Tanzania there was a significant increase (116.6%) of extrapulmonary cases reported between 1995 and 2009, suggesting the possibility of widespread M. bovis and Mycobacterium tuberculosis infection due to general rise of Human Immunodeficiency virus (HIV). This paper aims to review the potential health and economic impact of bovine tuberculosis and challenges to its control in order to safeguard human and animal population in Tanzania.

Modeling the dynamic relationship between HIV and the risk of drug-resistant tuberculosis

The emergence of highly drug-resistant tuberculosis (TB) and interactions between TB and HIV epidemics pose serious challenges for TB control. Previous researchers have presented several hypotheses for why HIV-coinfected TB patients may suffer an increased risk of drug-resistant TB (DRTB) compared to other TB patients. Although some studies have found a positive association between an individual's HIV status and his or her subsequent risk of multidrug-resistant TB (MDRTB), the observed individual-level relationship between HIV and DRTB varies substantially among settings. Here, we develop a modeling framework to explore the effect of HIV on the dynamics of DRTB. The model captures the acquisition of resistance to important classes of TB drugs, imposes fitness costs associated with resistance-conferring mutations, and allows for subsequent restoration of fitness because of compensatory mutations. Despite uncertainty in several key parameters, we demonstrate epidemic behavior that is robust over a range of assumptions. Whereas HIV facilitates the emergence of MDRTB within a community over several decades, HIV-seropositive individuals presenting with TB may, counterintuitively, be at lower risk of drug-resistant TB at early stages of the co-epidemic. This situation arises because many individuals with incident HIV infection will already harbor latent Mycobacterium tuberculosis infection acquired at an earlier time when drug resistance was less prevalent. We find that the rise of HIV can increase the prevalence of MDRTB within populations even as it lowers the average fitness of circulating MDRTB strains compared to similar populations unaffected by HIV. Preferential social mixing among individuals with similar HIV status and lower average CD4 counts among HIV-seropositive individuals further increase the expected burden of MDRTB. This model suggests that the individual-level association between HIV and drug-resistant forms of TB is dynamic, and therefore, cross-sectional studies that do not report a positive individual-level association will not provide assurance that HIV does not exacerbate the burden of resistant TB in the community.

Discovery of novel 5-(ethyl or hydroxymethyl) analogs of 2'-'up' fluoro (or hydroxyl) pyrimidine nucleosides as a new class of Mycobacterium tuberculosis, Mycobacterium bovis and Mycobacterium avium inhibitors

Discovery of novel antimycobacterial compounds that work on distinctive targets and by diverse mechanisms of action is urgently required for the treatment of mycobacterial infections due to the emerging global health threat of tuberculosis. We have identified a new class of 5-ethyl or hydroxy (or methoxy) methyl-substituted pyrimidine nucleosides as potent inhibitors of Mycobacterium bovis, Mycobacterium tuberculosis (H37Ra, H37Rv) and Mycobacterium avium. A series of 2'-'up' fluoro (or hydroxy) nucleosides (1, 2, 4-6, 9, 10, 13, 16, 18, 21, 24) was synthesized and evaluated for antimycobacterial activity. Among 2'-fluorinated compounds, 1-(3-bromo-2,3-dideoxy-2-fluoro-β-d-arabinofuranosyl)-5-ethyluracil (13) exhibited promising activity against M. bovis and Mtb alone, and showed synergism when combined with isoniazid. The most active compound emerging from these studies, 1-(β-d-arabinofuranosyl)-4-thio-5-hydroxymethyluracil (21) inhibited Mtb (H37Ra) (MIC(50)=0.5 μg/mL) and M. bovis (MIC(50)=0.5 μg/mL) at low concentrations, and was ten times more potent against Mtb (H37Ra) than cycloserine (MIC(50)=5.0 μg/mL), a second line drug. It also showed an additive effect when combined with isoniazid. Compound 21 retained sensitivity against a rifampicin-resistant (H37Rv) strain of Mtb (MIC(50)=1 μg/mL) at concentrations similar to that for a rifampicin-sensitive (H37Rv) strain, suggesting that it has no cross-resistance to a first-line anti-TB drug. In addition, the replication of M. avium was also inhibited by 21 (MIC(50)=10 μg/mL). No cellular toxicity of 13 or 21 was observed up to the highest concentration tested (CC(50)>100 μg/mL). These observations offer promise for a new drug treatment regimen to augment and complement the current chemotherapy of TB.

Rapid identification of mycobacteria and drug-resistant Mycobacterium tuberculosis by use of a single multiplex PCR and DNA sequencing

Tuberculosis (TB) remains a significant global health problem for which rapid diagnosis is critical to both treatment and control. This report describes a multiplex PCR method, the Mycobacterial IDentification and Drug Resistance Screen (MID-DRS) assay, which allows identification of members of the Mycobacterium tuberculosis complex (MTBC) and the simultaneous amplification of targets for sequencing-based drug resistance screening of rifampin-resistant (rifampin(r)), isoniazid(r), and pyrazinamide(r) TB. Additionally, the same multiplex reaction amplifies a specific 16S rRNA gene target for rapid identification of M. avium complex (MAC) and a region of the heat shock protein 65 gene (hsp65) for further DNA sequencing-based confirmation or identification of other mycobacterial species. Comparison of preliminary results generated with MID-DRS versus culture-based methods for a total of 188 bacterial isolates demonstrated MID-DRS sensitivity and specificity as 100% and 96.8% for MTBC identification; 100% and 98.3% for MAC identification; 97.4% and 98.7% for rifampin(r) TB identification; 60.6% and 100% for isoniazid(r) TB identification; and 75.0% and 98.1% for pyrazinamide(r) TB identification. The performance of the MID-DRS was also tested on acid-fast-bacterium (AFB)-positive clinical specimens, resulting in sensitivity and specificity of 100% and 78.6% for detection of MTBC and 100% and 97.8% for detection of MAC. In conclusion, use of the MID-DRS reduces the time necessary for initial identification and drug resistance screening of TB specimens to as little as 2 days. Since all targets needed for completing the assay are included in a single PCR amplification step, assay costs, preparation time, and risks due to user errors are also reduced.

Tuberculosis in special populations

The susceptibility to infection, the pathogenesis and the clinical manifestations of tuberculosis (TB) depend on the immunological status of the host. Immunological status is largely determined by age and comorbidities, but is also affected by other less well known factors. In Spain, most incidental cases of TB arise from the reactivation of remotely acquired latent infections and are favored by the aging of the population and the use of aggressive immunosuppressive therapies. The diagnosis and management of TB in these circumstances is often challenging. On the one hand, the atypical presentation with extrapulmonary involvement may delay diagnosis, and on the other, the toxicity and interactions of the antituberculous drugs frequently make treatment difficult. Immigration from resource-poor, high incidence TB countries, where the social and economic conditions are often suboptimal, adds a new challenge to the control of the disease in Spain. This chapter summarizes our current knowledge of epidemiological, clinical and treatment aspects of TB in particularly susceptible populations.

[Tuberculosis outbreak in a primary school: description and reflections on the value of gastric juice in the management of micro-epidemics]

AIMS

To describe a tuberculosis outbreak in a primary school arising from a secondary case.

METHODS

Contact study and clinical study of exposed patients. Chest x-ray, gastric aspirate processing, and clinical evaluation of all children with a positive tuberculin skin test (TST) were recorded. Differential diagnosis between tuberculosis disease (TB) and latent tuberculosis infection (LTI).

RESULTS

Two groups were identified: one of higher exposure to the index case (> 6 hours/day, for 3 months; n=17 children) and one of sporadic exposure (< 6 hours/day; n=82 children). Clinical or bacteriological criteria for diagnosing TB were seen in 6 out of 17 (35%) highly exposed children. Four of them had clinical or radiological criteria. The other two children were asymptomatic and had a normal chest X ray, but had a positive gastric aspirate for M. tuberculosis. The overall infection rate (TB+LTI) was 94%. One child out of 82 (1.2%) sporadically exposed children had radiological criteria for TB. Staff latent infection rate was 15%. Apart from the index case, there were no other tuberculosis cases among the staff. Relative risk (RR) of exposed children was 28.5 (95% CI: 3-250).

CONCLUSIONS

Prolonged exposure to a baciliferous patient may infect almost every child exposed in closed groups. It can also cause a high attack rate. In this scenario, routine gastric aspirate may be considered for all children with a positive TST. It may identify early subclinical TB with an increased probability of isolating the M. tuberculosis. The potential benefit of this isolation may reach the entire cohort.

The emergence of extensively drug-resistant tuberculosis: a global health crisis requiring new interventions: part I: the origins and nature of the problem

Surveillance studies and outbreak investigations indicate that an extensively drug-resistant (XDR) form of tuberculosis (TB) is increasing in prevalence worldwide. In outbreak settings among HIV-infected, there is a high-case fatality rate. Better outcomes occur in HIV-uninfected, particularly if drug susceptibility test (DST) results are available rapidly to allow tailoring of drug therapy. This review will be presented in two segments. The first characterizes the problem posed by XDR-TB, addressing the epidemiology and evolution of XDR-TB and treatment outcomes. The second reviews technologic advances that may contribute to the solution, new diagnostics, and advances in understanding drug resistance and in the development of new drugs.

[Multidrug-resistant tuberculosis]

The emergence and spread of Mycobacterium tuberculosis strains resistant to multiple drugs represent a threat for global tuberculosis control. The World Health Organization (WHO) estimates that almost 500,000 cases of M. tuberculosis resistant to isoniazid and rifampicin (multidrug-resistant, or MDR-TB), at least, emerged in 2006. In addition, new cases of extensively drug-resistant tuberculosis (XDR-TB), defined as MDR-TB with resistance to a fluoroquinolone and at least one second line injectable agent, have been reported in 45 countries in all five continents. Multidrug-resistant tuberculosis is an emerging problem in Spain but the impact of this disease is limited: the WHO estimates that 0.1% of new cases of tuberculosis and 4.3% of previously treated cases are MDR-TB. Treatment of MDR-TB is especially complicated, since this disease requires the use of drugs that are less effective and more toxic, requiring treatment to be administered over longer periods and severely reducing the probability of success. This situation poses a serious problem for low income countries, especially those with a high prevalence of human immunodeficiency virus type 1 (HIV-1) infection. MDR-TB and XDR-TB are also of special concern in wealthy countries, due to mass immigration. Therefore, tuberculosis resistant to multiple drugs should be given high priority in global public health and biomedical research.

Human tuberculosis due to Mycobacterium bovis in the United States, 1995-2005

BACKGROUND

Understanding the epidemiology of human Mycobacterium bovis tuberculosis (TB) in the United States is imperative; this disease can be foodborne or airborne, and current US control strategies are focused on TB due to Mycobacterium tuberculosis and airborne transmission. The National TB Genotyping Service's work has allowed systematic identification of M. tuberculosis-complex isolates and enabled the first US-wide study of M. bovis TB.

METHODS

Results of spacer oligonucleotide and mycobacterial interspersed repetitive units typing were linked to corresponding national surveillance data for TB cases reported for the period 2004-2005 and select cases for the period 1995-2003. We also used National TB Genotyping Service data to evaluate the traditional antituberculous drug resistance-based case definition of M. bovis TB.

RESULTS

Isolates from 165 (1.4%) of 11,860 linked cases were identified as M. bovis. Patients who were not born in the United States, Hispanic patients, patients <15 years of age, patients reported to be HIV infected, and patients with extrapulmonary disease each had increased adjusted odds of having M. bovis versus M. tuberculosis TB. Most US-born, Hispanic patients with TB due to M. bovis (29 [90.6%] of 32) had extrapulmonary disease, and their overall median age was 9.5 years. The National TB Genotyping Service's data indicated that the pyrazinamide-based case definition's sensitivity was 82.5% (95% confidence interval; 75.3%-87.9%) and that data identified 14 errors in pyrazinamide-susceptibility testing or reporting.

CONCLUSIONS

The prevalence of extrapulmonary disease in the young, US-born Hispanic population suggests recent transmission of M. bovis, possibly related to foodborne exposure. Because of its significantly different epidemiologic profile, compared with that of M. tuberculosis TB, we recommend routine surveillance of M. bovis TB. Routine surveillance and an improved understanding of M. bovis TB transmission dynamics would help direct the development of additional control measures.

Drug susceptibility of Spanish Mycobacterium tuberculosis complex isolates from animals

Mycobacterium bovis and Mycobacterium caprae are zoonotic bacteria that cause tuberculosis with several clinical manifestations. We have evaluated the susceptibility to anti-tuberculosis drugs of a panel of Spanish isolates of animal origin. The analysis of the sequence of the main genes involved in resistance was performed in 41 M. bovis and five M. caprae. The katG, inhA, rpsL, embB and gyrA genes had single nucleotide polymorphisms, not previously described in other organisms of the complex. Thirty-two M. bovis and three M. caprae isolates were tested for susceptibility to isoniazid (INH), rifampin, streptomycin, ethambutol, and ofloxacin using the standard proportion method. The results revealed that the isolates were sensitive to the five drugs. However, interference caused by sodium pyruvate in the INH test was detected: 94.3% grew at 0.2 microg INH/ml and 68.6% grew at 1 microg INH/ml. In the medium without pyruvate, 34.3% of the isolates did not grow whereas growth of the others was poor and slow. Nine M. bovis isolates were also tested by ESP Culture System II test and were sensitive to INH. The susceptibility of M. bovis to INH cannot be reliably determined using the standard proportion method due to the M. bovis growth requirements and the interference of pyruvate with INH.

Inhibition of Mycobacterium tuberculosis, Mycobacterium bovis, and Mycobacterium avium by Novel Dideoxy Nucleosides

The prevalence of tuberculosis (TB) and mutidrug-resistant tuberculosis (MDR-TB) has been increasing, leading to serious infections, high mortality, and a global health threat. Here, we report the identification of a novel class of dideoxy nucleosides as potent and selective inhibitors of Mycobacterium bovis, Mycobacterium tuberculosis, and drug-resistant Mycobacterium tuberculosis. A series of 5-acetylenic derivatives of 2',3'-dideoxyuridine (3-8) and 3'-fluoro-2',3'-dideoxyuridine (22-27) were synthesized and tested for their antimycobacterial activity against M. bovis, M. tuberculosis, and M. avium. 2',3'-Dideoxyuridine possessing 5-decynyl, 5-dodecynyl, 5-tridecynyl, and 5-tetradecynyl substituents (4-7) exhibited the highest antimycobacterial activity against all three mycobacteria. In contrast, in the 3'-fluoro-2',3'-dideoxyuridine series, a 5-tetradecynyl analogue (26) displayed the most potent activity against these mycobacteria. Among other derivatives, 5-bromo-2',3'-dideoxycytidine (11), 5-methyl-2',3'-dideoxycytidine (12), and 5-chloro-4-thio-2',3'-dideoxyuridine (19) exhibited modest inhibition of M. bovis and M. tuberculosis. In the series of dideoxy derivatives of adenosine, guanosine, and purines, 2-amino-6-mercaptoethyl-9-(2,3-dideoxy-beta-d-glyceropentofuranosyl)purine (32) and 2-amino-4-fluoro-7-(2,3-dideoxy-beta-d-glyceropentofuranosyl)pyrrolo[2,3-d]pyrimidine (35) were the most efficacious against M. bovis and M. tuberculosis, and M. avium, respectively.

Growth Inhibition of Mycobacterium bovis, Mycobacterium tuberculosis and Mycobacterium avium In Vitro: Effect of 1-β-d-2‘-Arabinofuranosyl and 1-(2‘-Deoxy-2‘-fluoro-β-d-2‘-ribofuranosyl) Pyrimidine Nucleoside Analogs

The resurgence of tuberculosis and the emergence of multiple-drug-resistant strains of Mycobacteria necessitate the search for new classes of antimycobacterial agents. We synthesized a series of 1-beta-D-2'-arabinofuranosyl and 1-(2'-deoxy-2'-fluoro-beta-D-ribofuranosyl) pyrimidine nucleosides possessing diverse sets of alkynyl, alkenyl, alkyl, and halo substituents at the C-5 position of the uracil and investigated their effect on activity against M. tuberculosis, M. bovis, and M. avium. Among these molecules, 5-alkynyl-substituted derivatives emerged as potent inhibitors of M. bovis, M. tuberculosis, and M. avium. Nucleosides 1-beta-D-2'-arabinofuranosyl-5-dodecynyluracil (5), 1-(2'-deoxy-2'-fluoro-beta-D-ribofuranosyl)-5-dodecynyluracil (24), and 1-(2'-deoxy-2'-fluoro-beta-D-ribofuranosyl)-5-tetradecynyluracil (25) showed the highest antimycobacterial potency against M. bovis and M. tuberculosis. The MIC90 exhibited by compounds 5, 24, and 25 was similar or close to that of the reference drug rifampicin. The most active compounds 5, 24, and 25 were also found to retain sensitivity against a rifampicin-resistant strain of M. tuberculosis H37Rv at similar concentrations. Some of these analogs also revealed in vitro antimicrobial effect against several other gram-positive pathogens.

Molecular epidemiology of multidrug-resistant Mycobacterium bovis isolates with the same spoligotyping profile as isolates from animals

PCR-based characterization techniques have been adopted in most laboratories for Mycobacterium bovis typing. We report a molecular characterization of human multidrug-resistant M. bovis isolates and three bovine isolates that share the spoligotyping profile. The analysis of the direct repeat region showed that both groups differed in the presence of spacers not included in the current membrane. They were also distinguished by two out of the nine mycobacterial interspersed repetitive unit variable-number tandem repeat loci tested, indicating that the human infection was not acquired from the cattle from which isolates were obtained. These results highlight that a combination of techniques is required for appropriate discrimination, even for those spoligotypes that have a low frequency.

Fatal case of tuberculous chancre in a patient with AIDS

Mycobacterium bovis is an unusual cause of tuberculosis. A fatal case of disseminated tuberculosis due to M. bovis with a chancre as a primary portal of entry and lymph node, pulmonary and renal involvement is presented in a patient with AIDS.

In vitro activity of linezolid against Mycobacterium tuberculosis complex, including multidrug-resistant Mycobacterium bovis isolates

The activity of linezolid was studied against 55 Mycobacterium tuberculosis (42 susceptible, 3 isoniazid resistant and 10 isoniazid and rifampicin resistant), one Mycobacterium bovis and two multidrug-resistant M. bovis isolates using the standard 7H10 agar proportion and the ESP Culture System II methods. Both methods displayed similar MIC(90) values (minimum inhibitory concentrations for 90% of the organisms) of 0.5mg/L; however, the former method yielded slightly lower MIC(50) values (MICs for 50% of the organisms) (0.25mg/L) compared with the latter method (0.5mg/L). No differences were observed between susceptible and resistant isolates, including multidrug-resistant M. bovis isolates, with a MIC range of 0.12-0.5mg/L. The potential role of linezolid in tuberculosis patients requires further in vivo evaluation.

Design and Studies of Novel 5-Substituted Alkynylpyrimidine Nucleosides as Potent Inhibitors of Mycobacteria

We herein report a new category of 5-substituted pyrimidine nucleosides as potent inhibitors of mycobacteria. A series of 5-alkynyl derivatives of 2'-deoxyuridine (1-8), 2'-deoxycytidine (9-14), uridine (15-17), and 2'-O-methyluridine (18, 19) were synthesized and evaluated for their antimycobacterial activity in vitro. 5-Decynyl, 5-dodecynyl, and 5-tetradecynyl derivatives showed the highest antimycobacterial potency against M. bovis and M. avium, with the 2'-deoxyribose derivatives being more effective than the ribose analogues. Nucleosides bearing short alkynyl side chains 5-ethynyl, 5-propynyl, 5-pentynyl, and 5-heptynyl were mostly not inhibitory. Incorporation of a phenylethynyl function at the 5-position diminished the antimicrobial effect. Furthermore, related bicyclic analogues (20-24) were devoid of antimycobacterial activity, indicating that an acyclic side chain at the C-5 position of the pyrimidine ring is essential for potent activity. Compounds 1-17 were synthesized by the Pd-catalyzed coupling reactions of respective alkynes with 5-iodo derivatives of 2'-deoxyuridine, 2'-deoxycytidine, and uridine. Intramolecular cyclization of 1 and 3-6 in the presence of Cu afforded the corresponding bicyclic compounds 20-24. The investigated nucleosides are recognized here for the first time to be potent inhibitors of mycobacteria. This class of compounds could be of interest for lead optimization as antimycobacterial agents.

Pleuropulmonary infections caused by Mycobacterium bovis: a re-emerging disease

Between 1980 and 2003, 13 patients (0.95% of all cases of tuberculosis) at a 600-bed university hospital in Madrid, Spain, were diagnosed with Mycobacterium bovis infection. All 13 cases occurred between 1994 and 1999; the mean age of the patients was 50 years (range 23-83 years), and 77% were males. Four (30%) patients were also positive for human immunodeficiency virus (HIV). The most frequent localisation of the disease was the lung (ten patients; 77%). Seven patients, including four HIV-positive patients who died, had multidrug-resistant M. bovis infection. No other patient died, including two HIV-negative patients with multidrug-resistant disease.

Determinants of health system delay among confirmed tuberculosis cases in Spain

BACKGROUND

Health system delay (HSD) is an important issue in tuberculosis (TB) control. This report investigates HSD and associated factors in a cohort of Spanish culture-confirmed TB patients.

METHODS

Data were collected from clinical records. Using logistic regression with two different cut-off points to define HSD (median and 75th percentile), adjusted odds ratios were used to estimate the association between HSD and different variables.

RESULTS

A total of 5184 culture-confirmed TB cases were included. Median and 75th percentile HSD were 6 and 25 days respectively. HSD significantly greater than the median was associated with: age >44 years, past or present intravenous drug use, diagnosis at a primary-care centre, prior preventive therapy, positive histology, request for drug-sensitivity testing, presence of silicosis or neoplasia in addition to TB, presence of non-TB related symptoms, and gastrointestinal site. HSD greater than the 75th percentile was related to the same variables, with the exception of diagnosis at a primary-care centre, positive histology, silicosis, non-TB-related symptoms and gastrointestinal site, for which the association disappeared; in contrast, an association with female gender emerged.

CONCLUSION

Despite free health care being universally available in Spain, there are some groups of TB patients whose treatment is unduly delayed.

Linezolid for the treatment of multidrug-resistant tuberculosis

OBJECTIVES

In vitro studies have shown good activity of linezolid against Mycobacterium tuberculosis, including multidrug-resistant strains. However, clinical experience with linezolid in tuberculosis is scarce.

METHODS

We report our clinical experience with five consecutive patients with multidrug-resistant tuberculosis infection treated with combination regimens that included linezolid.

RESULTS

Two patients had multidrug-resistant Mycobacterium bovis infection, with resistance to 12 antituberculous agents (one of them with HIV co-infection and <50 CD4 cells/mm(3)). The other three patients were infected by multidrug-resistant M. tuberculosis strains, with resistance to all first-line drugs and other second-line drugs. All patients received linezolid in combination with thiacetazone, clofazimine or amoxicillin/clavulanate. Susceptibility tests showed linezolid MIC values < or =0.5 mg/L against all tuberculosis strains tested (standard proportion method, Middlebrook agar 7H10). In all cases, tuberculosis cultures from respiratory samples were sterile after 6 weeks of therapy. Three patients have clinical and microbiological cure of tuberculosis with a combination regimen with linezolid (range: 5-24 months). One patient was lost to follow-up at month 5. The remaining patient has completed 11 months of therapy and is still on treatment. Four patients developed anaemia and needed blood transfusions. In two of these patients, the linezolid daily-dose (600 mg twice a day) was successfully reduced to 50% (300 mg twice a day) to decrease toxicity while maintaining efficacy. Peripheral neuropathy (two patients) and pancreatitis (one patient) were other adverse events observed during linezolid treatment.

CONCLUSIONS

In our experience, linezolid has been a valid alternative drug in the management of multidrug-resistant tuberculosis. The prolonged use of linezolid is frequently associated with toxicity, mainly anaemia and peripheral neuropathy, that requires special management.

Systematic molecular characterization of multidrug-resistant Mycobacterium tuberculosis complex isolates from Spain

We used spoligotyping and restriction fragment length polymorphism (RFLP) of the IS6110-insertion sequence to study the molecular epidemiology of multidrug-resistant (MDR) tuberculosis in Spain. We analyzed 180 Mycobacterium tuberculosis complex isolates collected between January 1998 and December 2000. Consecutive isolates from the same patients (n = 23) always had identical genotypes, meaning that no cases of reinfection occurred. A total of 105 isolates (58.3%) had unique RFLP patterns, whereas 75 isolates (41.7%) were in 20 different RFLP clusters. Characterization of the katG and rpoB genes showed that 14 strains included in the RFLP clusters did not actually cluster. Only 33.8% of the strains isolated were suggestive of MDR transmission, a frequency lower than that for susceptible strains in Spain (46.6%). We found that the Beijing/W genotype, which is prevalent worldwide, was significantly associated with immigrants. The 22 isolates in the largest cluster corresponded to the Mycobacterium bovis strain responsible for two nosocomial MDR outbreaks in Spain.

Prolonged Survival of an HIV-Infected Patient with Multidrug-Resistant Mycobacterium bovis Infection Treated with Surgical Resection

We describe a case of multidrug-resistant tuberculosis due to Mycobacterium bovis in a human immunodeficiency virus-infected woman with good immunologic status. The patient presented with a hard mass measuring 10 cm in diameter on the lower left ribs and a lung nodule measuring 3 cm in diameter in the left superior lobe. No adequate pharmacological treatment was available. Both lesions were surgically resected. The patient has remained asymptomatic (without fever, cough, lymphadenopathy, or cutaneous masses) for 20 months, after discharge from the hospital.

Hypermutation as a Factor Contributing to the Acquisition of Antimicrobial Resistance

Contrary to what was thought previously, bacteria seem to be, not merely spectators to their own evolution, but, through a variety of mechanisms, able to increase the rate at which mutations occur and, consequently, to increase their chances of becoming resistant to antibiotics. Laboratory studies and mathematical models suggest that, under stressful conditions, such as antibiotic challenge, selective pressure favors mutator strains of bacteria over nonmutator strains. These hypermutable strains have been found in natural bacterial populations at higher frequencies than expected. The presence of mutator strains in the clinical setting may indicate an enhanced risk of acquiring antibiotic resistance through mutational and recombinational events. In addition, some antibiotics are inducers of mechanisms that transiently increase the mutation rate, and thus probably act, not only as mere selectors of antibiotic resistant clones, but also as resistance-promoters.

Control of Mycobacterium bovis infections and the risk to human populations

Conventional control methods based on test-and-slaughter policies have, in several countries, led to the successful eradication of bovine tuberculosis in cattle. However, new approaches for control of bovine tuberculosis are required in developing countries and those with a wildlife reservoir of infection. Recent developments include improved diagnostics and evaluation of new vaccination strategies.