Evaluation of effectiveness of mass screening for tuberculosis infection in children from 1 to 7 years old in Moscow

The objective: to evaluate effectiveness of mass screening for tuberculosis infection in children aged 1 to 7 years in different periods – before and after the use of tuberculosis recombinant allergen skin test (TRA) in primary health care as an additional diagnostic method.Subjects and Methods. The study was designed as continuous observational prospective-retrospective study. Two different periods were assessed: the first one was 2014-2016 when screening for tuberculosis infection was performed in all children from 1 to 17 years (inclusive) using Mantoux test with 2 TU PPD-L in pediatric primary health care, and then children suspected to have a positive reaction were referred to TB dispensary where they were examined with a skin test with TRA if necessary. The second period was from 2018 to 2020 when children of 1-7 years old were given Mantoux test and if tuberculosis infection was suspected, a skin test with TRA was done both in primary health care network and TB units. In the first 3 years, 1,864,137 children were examined and in the second 3 years, 2,078,800 children from 1 to 7 years old were examined.Results. Among children of 1-7 years old who were screened by two stages (initial Mantoux test, and then in those who had a positive reaction, the TRA test was used), only 10-12% of those referred to a phthisiologist were subject to dispensary follow-up. Thus, with the implementation of the new edict on screening for tuberculosis infection in children with two tests, this proportion has not changed compared to previous years, when screening was carried out only with one Mantoux test. The reason why almost 90% of the children who were referred to TB Dispensary were not subject to dispensary follow-up is the following: children who have had previous conversion of tuberculin tests, along with everyone else are again screened with Mantoux test despite being previously followed up by TB dispensary due to the primary infection.Recommendations:Currently, there is no division of Group VI into Subgroups A, B, C in the dispensary follow up grouping. Why should conversion of Mantoux test reaction from negative into positive not be considered an infection, and the increase in the reaction must be at least 6 mm.Since Order No. 124n of the Russian Ministry of Health allows testing with TRA in the primary health care in case of suspected infection, it is advisable to refer those who have already had this test to a phthisiologist.A child with conversion of Mantoux test should not be re-screened with Mantoux test but the TRA test should be used. If a positive reaction to the TRA test occurs for the first time, it should be considered as conversion of this test, and in this case the child should be examined by computed tomography (CT), and preventive therapy should be prescribed. If in subsequent years the TRA reaction increases by at least 6 mm after previous preventive therapy, the child should be re-referred for CT to rule out the development of active tuberculosis.

Improving screening and management of latent tuberculosis infection: development and evaluation of latent tuberculosis infection primary care model

Background In Australia, demand for specialist infectious diseases services exceeds capacity to provide timely management of latent tuberculosis infection (LTBI) in areas of high refugee and asylum seeker settlement. A model for treating LTBI patients in primary care has been developed and piloted in a refugee-focused primary health service (Monash Health Refugee Health and Wellbeing [MHRHW]) and a universal primary care clinic. This study reports on the development and evaluation of the model, focusing on the model feasibility, and barriers and enablers to its success. Methods A convergent mix-methods design was used to evaluate the model for treating LTBI patients in primary care, where a prospective cohort study of patients commencing treatment either at MHRHW or the universal primary care clinic determined the model feasibility, while focus groups with clinicians directly involved in treating these patients explored barriers and enablers to sustainability and success of the model. Results From January 2017 to April 2018, 65 patients with confirmed LTBI presented at participating clinics. Treatment was accepted by 31 (48%) patients, of whom 15(48%) were treated at MHRHW and 16 (52%) at the universal primary care clinic. The 6-months’ treatment completion rate was higher at MHRHW compared to the universal primary care clinic (14 (93%) compared to 9 (56%) respectively, p = 0.0373). Reasons for non-completion included adverse reaction, opting out and relocation. At the completion of the pilot, 15 clinicians participated in two focus groups. Clinicians identified barriers and enablers for successful LTBI management at patient, provider, organisational and clinical levels. While barriers for treatment completion and adherence were consistent across the two pilot sites, enablers, such as resources to facilitate patient education and follow-up, were available only at MHRHW. Conclusion Screening and management of LTBI patients can be achieved within the primary care setting, considerate of barriers and enablers at patient, provider, organisational and clinical levels. Upscaling of a primary care response to the management of LTBI will require supporting primary care clinics with resources to employ dedicated clinical staff for patient education, follow-up communication and monitoring medication adherence.

Glutamine is required for M1-like polarization in response to Mycobacterium tuberculosis infection

In response to Mycobacterium tuberculosis infection, macrophages mount early proinflammatory and antimicrobial responses similar to those observed in M1 macrophages classically activated by LPS and IFN-γ. A metabolic reprogramming to HIF-1-mediated uptake of glucose and its metabolism by glycolysis is required for M1-like polarization, but little is known about other metabolic programs driving M1-like polarization during M. tuberculosis infection. Identification and quantification of labeling patterns of U 13 C glutamine and U 13 C glucose-derived metabolites demonstrated that glutamine, rather than glucose, is catabolized in both the oxidative and reductive TCA cycle of M1-like macrophages, thereby generating signaling molecules that include succinate, biosynthetic precursors such as aspartate, and the antimicrobial metabolite itaconate. This conclusion is corroborated by diminished M1 polarization via chemical inhibition of glutaminase (GLS), the key enzyme of the glutaminolysis pathway, and by genetic deletion of GLS in infected macrophages. Furthermore, characterization of the labeling distribution pattern of U 15 N glutamine in M1-like macrophages indicates that glutamine serves as a nitrogen source for the synthesis of intermediates of purine and pyrimidine metabolism plus amino acids including aspartate. Thus, the catabolism of glutamine, as an integral component of metabolic reprogramming in activating macrophages, fulfills the cellular demand for bioenergetic and biosynthetic precursors of M1-like macrophages. Knowledge of these new immunometabolic features of M1-like macrophages is expected to advance the development of host-directed therapies that will enhance bacterial clearance and prevent immunopathology during tuberculosis.

A blunted GPR183/oxysterol axis during dysglycemia results in delayed recruitment of macrophages to the lung during M. tuberculosis infection

We previously reported that the oxidised cholesterol-sensing receptor GPR183 is significantly downregulated in blood from tuberculosis (TB) patients with diabetes compared to TB patients without co-morbidities and that lower GPR183 expression in blood is associated with more severe pulmonary TB on chest-x-ray consistent with observations in dysglycemic mice. To further elucidate the role of this receptor and its endogenous high affinity agonist 7α,25-dihydroxycholesterol (7α,25-OHC) in the lung, we studied high fat diet (HFD)-induced 28 dysglycemic mice infected with M.tuberculosis. We found that the 7α,25-OHC-producing enzymes cholesterol 25-hydroxylase (CH25H) and cytochrome P450 family 7 subfamily member B1 (CYP7B1) were highly upregulated upon M.tuberculosis infection in the lungs of normoglycemic mice, and this was associated with increased expression of GPR183 indicative of effective recruitment of GPR183-expressing immune cells to the site of infection. We demonstrated that CYP7B1 was predominantly expressed by macrophages in the centre of TB granulomas. Expression of CYP7B1 was significantly blunted in lungs from HFD-fed dysglycemic animals and this coincided with 36 delayed recruitment of macrophages to the lung during early infection and more severe lung pathology. GPR183 deficient mice similarly had reduced macrophage recruitment during early infection demonstrating a requirement of the GPR183/oxysterol axis for macrophage infiltration into the lung in TB. Together our data demonstrate that oxidised cholesterols and GPR183 play an important role in positioning macrophages to the site of M. tuberculosis infection and that this is impaired by HFD-induced dysglycemia, adding a mechanistic explanation to the poorer TB outcomes in patients with diabetes.