Extrapulmonary nontuberculous mycobacterial infections: a guide for the general physician

Non-tuberculous mycobacteria (NTM) infections predominantly present as pulmonary disease. Although relatively rare, 20-30 % originate from extrapulmonary sites resulting in a wide range of clinical syndromes. Immunocompromised individuals are particularly susceptible. Clinical manifestations include skin and soft-tissue infections, lymphadenitis, musculoskeletal infections and disseminated disease. Diagnosing extrapulmonary NTM is challenging, and management is complex, often involving multiple radiological and microbiological investigations, long courses of combination antibiotic regimens and may require adjuvant surgical interventions. We highlight both the importance of involving NTM experts at an early stage and the role of a multidisciplinary approach in the diagnosis and management of these infections.

Prognostic value of interferon-γ release assays and tuberculin skin test in predicting the development of active tuberculosis (UK PREDICT TB): a prospective cohort study

BACKGROUND

Tackling tuberculosis requires testing and treatment of latent tuberculosis in high-risk groups. The aim of this study was to estimate the predictive values of the tuberculin skin test (TST) and two interferon-γ release assays (IGRAs) for the development of active tuberculosis in high-risk groups-ie, people in recent contact with active tuberculosis cases and from high-burden countries.

METHOD

In this prospective cohort study, we recruited participants from 54 centres (eg, clinics, community settings) in London, Birmingham, and Leicester in the UK. Participants were eligible if they were aged 16 years or older and at high risk for latent tuberculosis infection (ie, recent contact with someone with active tuberculosis [contacts] or a migrant who had arrived in the UK in the past 5 years from-or who frequently travelled to-a country with a high burden of tuberculosis [migrants]). Exclusion criteria included prevalent cases of tuberculosis, and participants who were treated for latent tuberculosis after a positive test result in this study. Each participant received three tests (QuantiFERON-TB Gold-In Tube, T-SPOT.TB, and a Mantoux TST). A positive TST result was reported using three thresholds: 5 mm (TST-5), 10 mm (TST-10), and greater than 5 mm in BCG-naive or 15 mm in BCG-vaccinated (TST-15) participants. Participants were followed up from recruitment to development of tuberculosis or censoring. Incident tuberculosis cases were identified by national tuberculosis databases, telephone interview, and review of medical notes. Our primary objective was to estimate the prognostic value of IGRAs compared with TST, assessed by the ratio of incidence rate ratios and predictive values for tuberculosis development. The study was registered with ClinicalTrials.gov, NCT01162265, and is now complete.

FINDINGS

Between May 4, 2010, and June 1, 2015, 10 045 people were recruited, of whom 9610 were eligible for inclusion. Of this cohort, 4861 (50·6%) were contacts and 4749 (49·4%) were migrants. Participants were followed up for a median of 2·9 years (range 21 days to 5·9 years). 97 (1·0%) of 9610 participants developed active tuberculosis (77 [1·2%] of 6380 with results for all three tests). In all tests, annual incidence of tuberculosis was very low in those who tested negatively (ranging from 1·2 per 1000 person-years, 95% CI 0·6-2·0 for TST-5 to 1·9 per 1000 person-years, 95% CI 1·3-2·7, for QuantiFERON-TB Gold In-Tube). Annual incidence in participants who tested positively were highest for T-SPOT.TB (13·2 per 1000 person-years, 95% CI 9·9-17·4), TST-15 (11·1 per 1000 person-years, 8·3-14·6), and QuantiFERON-TB Gold In-Tube (10·1 per 1000 person-years, 7·4-13·4). Positive results for these tests were significantly better predictors of progression than TST-10 and TST-5 (eg, ratio of test positivity rates in those progressing to tuberculosis compared with those not progressing T-SPOT.TB vs TST-5: 1·99, 95% CI 1·68-2·34; p<0·0001). However, TST-5 identified a higher proportion of participants who progressed to active tuberculosis (64 [83%] of 77 tested) than all other tests and TST thresholds (≤75%).

INTERPRETATION

IGRA-based or BCG-stratified TST strategies appear most suited to screening for potential disease progression among high-risk groups. Further work will be needed to assess country-specific cost-effectiveness of each screening test, and in the absence of highly specific diagnostic tests, cheap non-toxic treatments need to be developed that could be given to larger groups of people at potential risk.

FUNDING

National Institute for Health Research Health Technology Assessment Programme 08-68-01.

The risk of tuberculosis in transplant candidates and recipients: a TBNET consensus statement

Tuberculosis (TB) is a possible complication of solid organ and hematopoietic stem cell transplantation. The identification of candidates for preventive chemotherapy is an effective intervention to protect transplant recipients with latent infection with Mycobacterium tuberculosis from progressing to active disease. The best available proxy for diagnosing latent infection with M. tuberculosis is the identification of an adaptive immune response by the tuberculin skin test or an interferon-γ based ex vivo assay. Risk assessment in transplant recipients for the development of TB depends on, among other factors, the locally expected underlying prevalence of infection with M. tuberculosis in the target population. In areas of high prevalence, preventive chemotherapy for all transplant recipients may be justified without immunodiagnostic testing while in areas of medium and low prevalence, preventive chemotherapy should only be offered to candidates with positive M. tuberculosis-specific immune responses. The diagnosis of TB in transplant recipients can be challenging. Treatment of TB is often difficult due to substantial interactions between anti-TB drugs and immunosuppressive medications. This management guideline summarises current knowledge on the prevention, diagnosis and treatment of TB related to solid organ and hematopoietic stem cell transplantation and provides an expert consensus on questions where scientific evidence is still lacking.

An unusual cause of bronchial obstruction

We present here a case of bronchial obstruction secondary to late paradoxical reactive enlargement and erosion by mediastinal lymph nodes into the left main bronchus in a 26-year-old woman with tuberculosis lymphadenitis. Bronchial obstruction due to paradoxical reactions, especially in the late phase of treatment, has not been described in adults before.

Guidelines for the prevention and management of Mycobacterium tuberculosis infection and disease in adult patients with chronic kidney disease

Guidelines have been compiled by the Joint Tuberculosis Committee of the British Thoracic Society for the prevention and management of Mycobacterium tuberculosis infection and disease in patients with all grades of renal impairment.

Tuberculosis and HIV seroprevalence in Lambeth, Southwark and Lewisham, an area of South London

Since the mid-1980s the number of cases of TB notified within the U.K. has continued to rise although the contribution of HIV to this rise remains unclear. A 12-month prospective cohort study was conducted at chest and HIV clinics in four hospitals in Lambeth, Southwark and Lewisham (LSL), an area of South London, to determine the proportion of patients with culture-proven TB infected with HIV. Secondary aims were to determine the proportion of patients with TB and undiagnosed HIV at first presentation to chest clinics, to determine the proportion of patients presenting with TB as an AIDS defining illness (ADI) and to identify risk factors for co-infection with TB and HIV. In chest clinics, demographic data and left-over blood from patients aged 16 or over with culture-proven TB was collected, anonymised and HIV tested. In HIV clinics, demographic data on patients with TB already known to be HIV seropositive were also obtained. Twenty-one patients (13%, 95% CI-8-19%) of 159 with culture-proven TB were infected with HIV Four (3%) of 133 patients at first presentation to chest clinics had undiagnosed HIV; two were subsequently diagnosed. Of the 21 patients withTB and HIV, nine (43%) presented with TB as an ADI. Patients with TB and HIV were significantly more likely to be aged between 35 and 55 years compared to HIV seronegative patients [12/21 (57%) vs. 38/138 (28%), P=0.006]. None of the patients from the Indian Subcontinent were HIV seropositive [0/21 vs. 25/138 (18%), P=0.047]. At the present time, universal HIV testing of patients with culture-provenTB in chest clinics within the U.K. is unlikely to significantly reduce the number of patients with undiagnosed HIV.

Pulmonary cryptosporidiosis occurring in a bone marrow transplant patient

We describe what is believed to be the first bone marrow transplant patient, a 32-year-old man, in whom pulmonary cryptosporidiosis was associated with terminal respiratory failure. The diagnosis, treatment and postmortem histology are discussed together with a brief review of the literature.