Human Cytomegalovirus-Induced Interleukin-10 Production Promotes the Proliferation of Mycobacterium massiliense in Macrophages.

Human cytomegalovirus (HCMV) exploits the interleukin-10 (IL-10) pathway as a part of its infection cycle through the manipulation of the host IL-10 signaling cascade. Based on its immunomodulatory nature, HCMV attenuates the host immune response and facilitates the progression of co-infection with other pathogens in an immune-competent host. To investigate the impact of HCMV infection on the burden of non-tuberculous mycobacteria (NTM), whose prevalence is growing rapidly worldwide, macrophages were infected with HCMV and further challenged with Mycobacterium massiliense in vitro. The results showed that HCMV infection significantly increased host IL-10 synthesis and promoted the proliferation of M. massiliense in an IL-10-dependent manner. Transcriptomic analysis revealed that HCMV infection dampened the regulatory pathways of interferon gamma (IFN-γ), tumor necrosis factor alpha (TNF-α), and interleukin-1 (IL-1), consequently abrogating the immune responses to M. massiliense coinfection in macrophages. These findings provide a mechanistic basis of how HCMV infection may facilitate the development of pathogenic NTM co-infection by upregulating IL-10 expression.

Nontuberculous mycobacteria in cervical lymphadenopathies of HIV positive and HIV-negative adults / Micobacterias no tuberculosas en linfadenopatías cervicales de adultos VIH positivos y VIH negativos

Background: Tuberculosis is a global public health problem, especially in emerging countries. Mycobacterium tuberculosis is the main cause of cervical lymphadenopathy; nontuberculous mycobacteria are relatively common in children and rare in adults. Objective: To identify and establish the frequency of infectious etiology by nontuberculous mycobacteria in Mexican adult patients with cervical lymphadenopathy. Methods: The study included 85 patients over 18 years with cervical lymphadenopathy; 45 were HIV-positive, 40 were HIV-negative; they had no history of tuberculosis treatment and were selected from a third-level hospital. It was carried out a biopsy of the lymph node for the histopathological study, a search for acid-fast bacilli, a tube culture to indicate growth of Mycobacterium BACTEC (MGIT-960) and identification of mycobacterial strain by PCR-RFLP (restriction fragment length polymorfism) of hsp65. Results: In 42 HIV-positive patients (93%), strains corresponded to Mycobacterium tuberculosis complex, two (4.4%) to M. intracellulare and one (2.2%) to M. gordonae. Among HIV-negative patients, 39 of strains (97.5%) corresponded to patients with M. tuberculosis complex and one strain (2.5%) to M. fortuitum. Conclusion: The presence of nontuberculous mycobacteria was found in 4.7% of all cases. Despite this low frequency, it must be taken into account as a possible cause of lymphadenopathy, since its prompt identification enables introducing specific treatment.

Introducción: la tuberculosis es un problema de salud pública mundial, sobre todo en países emergentes. El Mycobacterium tuberculosis es el principal causante de las adenopatías cervicales; las micobacterias no tuberculosas son relativamente frecuentes en el niño y raras en adultos. Objetivo: identificar y establecer la frecuencia de la etiología infecciosa por micobacterias no tuberculosas (MNT) en pacientes adultos mexicanos con linfadenopatias cervicales. Métodos: se estudiaron 85 pacientes mayores de 18 años, con linfadenopatía cervical, 45 con positividad al virus de la inmunodeficiencia humana (VIH) y 40 VIH negativos, sin antecedentes de tratamiento antituberculoso, seleccionados en un hospital de concentración de especialidad de tercer nivel. Se realizó biopsia de nodo linfático para su estudio histopatológico, búsqueda de bacilos ácido-alcohol resistentes, cultivo en el tubo indicador del crecimiento de Mycobacterium BACTEC (MGIT-960) y la identificación de cepa micobacteriana por PCR-RFLP (restriction fragment lenght polymorfism) de hsp65. Resultados: las cepas correspondieron al complejo Mycobacterium tuberculosis en 42 pacientes VIH positivos (93%), dos (4.4%) a M. intracellulare y una (2.2%) a M. gordonae. Las cepas correspondieron al complejo M. tuberculosis en 39 pacientes VIH negativos (97.5%) y una a M. fortuitum (2.5%). Conclusión: la presencia de MNT se encontró en 4.7% de todos los casos. A pesar de su baja frecuencia, deben ser tomadas en cuenta como posible causa de linfadenopatías, porque su identificación oportuna permite instaurar un tratamiento específico.

Mycobacterium marinum antagonistically induces an autophagic response while repressing the autophagic flux in a TORC1- and ESX-1-dependent manner.

Autophagy is a eukaryotic catabolic process also participating in cell-autonomous defence. Infected host cells generate double-membrane autophagosomes that mature in autolysosomes to engulf, kill and digest cytoplasmic pathogens. However, several bacteria subvert autophagy and benefit from its machinery and functions. Monitoring infection stages by genetics, pharmacology and microscopy, we demonstrate that the ESX-1 secretion system of Mycobacterium marinum, a close relative to M. tuberculosis, upregulates the transcription of autophagy genes, and stimulates autophagosome formation and recruitment to the mycobacteria-containing vacuole (MCV) in the host model organism Dictyostelium. Antagonistically, ESX-1 is also essential to block the autophagic flux and deplete the MCV of proteolytic activity. Activators of the TORC1 complex localize to the MCV in an ESX-1-dependent manner, suggesting an important role in the manipulation of autophagy by mycobacteria. Our findings suggest that the infection by M. marinum activates an autophagic response that is simultaneously repressed and exploited by the bacterium to support its survival inside the MCV.

Characterizing Non-Tuberculous Mycobacteria Infection in Bronchiectasis.

Chronic airway infection is a key aspect of the pathogenesis of bronchiectasis. A growing interest has been raised on non-tuberculous mycobacteria (NTM) infection. We aimed at describing the clinical characteristics, diagnostic process, therapeutic options and outcomes of bronchiectasis patients with pulmonary NTM (pNTM) disease. This was a prospective, observational study enrolling 261 adult bronchiectasis patients during the stable state at the San Gerardo Hospital, Monza, Italy, from 2012 to 2015. Three groups were identified: pNTM disease; chronic P. aeruginosa infection; chronic infection due to bacteria other than P. aeruginosa. NTM were isolated in 32 (12%) patients, and among them, a diagnosis of pNTM disease was reached in 23 cases. When compared to chronic P. aeruginosa infection, patients with pNTM were more likely to have cylindrical bronchiectasis and a "tree-in-bud" pattern, a history of weight loss, a lower disease severity and a lower number of pulmonary exacerbations. Among pNTM patients who started treatment, 68% showed a radiological improvement, and 37% achieved culture conversion without recurrence, while 21% showed NTM isolation recurrence. NTM isolation seems to be a frequent event in bronchiectasis patients, and few parameters might help to suspect NTM infection. Treatment indications and monitoring still remain an important area for future research.

Non-tuberculous mycobacterial infections at San Francisco General Hospital.

BACKGROUND AND AIMS: The epidemiology of non-tuberculous mycobacteria (NTM) infection is not well defined. We evaluated the trends in incidence of NTM infections at San Francisco General Hospital (SFGH), a large metropolitan county hospital. METHODS: We performed a retrospective review of microbiologic and clinical records of all patients with a positive NTM culture reported from 1993 to 2001. NTM infection was defined by the isolation of >1 NTM from any clinical specimen. Patients were stratified by human immunodeficiency virus (HIV) status. Univariate and multivariate logistic regression were used to identify factors that were independently associated with NTM infection. Trends over time were assessed using Poisson test for trend. RESULTS: During the study period, 25 736 samples from 7395 patients were cultured for mycobacteria. Of these samples, 2853 (11.1%) from 1345 patients (18.2%) were culture positive for NTM. Patient characteristics associated with infection included younger age (P < 0.001), male gender (P < 0.001), White ethnicity compared with Asian and Hispanic (P < 0.001 and P = 0.01, respectively), and HIV positivity (P < 0.001). Overall, NTM infection at SFGH decreased significantly from 319 cases in 1993 to 59 in 2001 (P < 0.001). Mycobacterium avium was predominant in both HIV-positive and HIV-negative populations (74.5% and 44.6% of isolates, respectively), and Mycobacterium kansasii was the second most common NTM species isolated. The proportion of other NTM species isolated in these groups differed. CONCLUSION: In contrast to other published studies, time-series analyses show that NTM isolation rates decreased during the study period at SFGH, where NTM was most strongly associated with HIV infection.

Multi-drug resistant non-tuberculous mycobacteria infection in a non-HIV infected child.

Non-tuberculous mycobacteria (NTM) are widely dispersed in our environment. Pulmonary disease, lymphadenitis, skin and soft tissue infections, bone and joint infections and disseminated infections are common clinical syndromes in immuno-compromised patients. NTM infections are frequently overlooked in developing countries like India withendemic TB due to non-specific clinical manifestations, unfamiliarity of clinicians with mycobacteria, and inadequacy of laboratory services. Here we report a case of multidrug resistant (MDR) pulmonary NTM infection in a non-HIV infected child and her response to therapy.

Cytomegalovirus disease in patients with common variable immunodeficiency: three case reports.

Common variable immunodeficiency (CVID) is the most frequent clinically relevant primary immunodeficiency and shows enormous heterogeneity in clinical presentation. Despite clinical immunodeficiency, opportunistic infections are not a typical manifestation of CVID. A retrospective study of 32 patients followed up for 335 patient-years was performed to determine the frequency of cytomegalovirus (CMV) disease. Symptomatic CMV infection was documented in 3 CVID patients. Patients No. 1 and 2 suffered from CMV pneumonia, with complications due to atypical mycobacteriosis in patient No. 1. Patient No. 3 suffered from CMV enteritis. A history of cancer and chronic hepatitis C infection (patient No. 1), immunosuppressive therapy for interstitial lung disease (patient No. 2) and serious enteropathy complicated with malnutrition (patient No. 3) may have contributed to the complications despite only mild abnormalities in T-cell subpopulations. The direct detection of CMV in bronchoalveolar lavage, stool or tissue samples was the most beneficial diagnostic laboratory method, whereas the detection of CMV DNA in blood did not produce positive results. Adequate treatment of CMV disease led to significant clinical improvement in all 3 patients. The frequency of CMV disease appears to be higher than previously described. In our experience, the probability of opportunistic infections in CVID patients increases with secondary comorbidities and their management.

The dUTPase enzyme is essential in Mycobacterium smegmatis.

Thymidine biosynthesis is essential in all cells. Inhibitors of the enzymes involved in this pathway (e.g. methotrexate) are thus frequently used as cytostatics. Due to its pivotal role in mycobacterial thymidylate synthesis dUTPase, which hydrolyzes dUTP into the dTTP precursor dUMP, has been suggested as a target for new antitubercular agents. All mycobacterial genomes encode dUTPase with a mycobacteria-specific surface loop absent in the human dUTPase. Using Mycobacterium smegmatis as a fast growing model for Mycobacterium tuberculosis, we demonstrate that dUTPase knock-out results in lethality that can be reverted by complementation with wild-type dUTPase. Interestingly, a mutant dUTPase gene lacking the genus-specific loop was unable to complement the knock-out phenotype. We also show that deletion of the mycobacteria-specific loop has no major effect on dUTPase enzymatic properties in vitro and thus a yet to be identified loop-specific function seems to be essential within the bacterial cell context. In addition, here we demonstrated that Mycobacterium tuberculosis dUTPase is fully functional in Mycobacterium smegmatis as it rescues the lethal knock-out phenotype. Our results indicate the potential of dUTPase as a target for antitubercular drugs and identify a genus-specific surface loop on the enzyme as a selective target.

Immune reconstitution syndrome from nontuberculous mycobacterial infection after initiation of antiretroviral therapy in children with HIV infection.

The immune reconstitution syndrome caused by nontuberculous mycobacterial (NTM) infection is reported in 9 of 153 HIV-infected children 2 to 26 weeks after initiation of antiretroviral therapy. The clinical syndrome included fever and dyspnea (2 children), fever and abdominal pain (3), subcutaneous nodules or suppurative lymphadenitis (4). The causative species were Mycobacterium avium (4), Mycobacterium scrofulaceum (3), Mycobacterium kansasii (1) and Mycobacterium simiae (1).

Localized pulmonary infection associated with Mycobacterium tilburgii in an HIV-infected patient.

The case of an HIV-infected patient with low CD4+ cell count and localized pulmonary infection associated with Mycobacterium tilburgii, a recently recognized atypical mycobacterial species, is reported. Diagnosis was confirmed by repeated detection of mycobacterial DNA in lung biopsy specimens. After surgical removal of the pulmonary nodules, treatment with antimycobacterial combination therapy led to a complete and sustained recovery of the respiratory symptoms.M. tilburgii so far has only been described to cause disseminated infection in three patients, two of them suffering from acquired immunodeficiency syndrome. To our knowledge, this is the first report of localized pulmonary disease attributed to this mycobacterial species. As it responds to antimycobacterial combination therapy, efforts to establish the diagnosis using PCR methods in patients with suspected pulmonary disease due to mycobacteria other than tuberculosis should be undertaken.

HIV-related nontuberculous mycobacterial infection: incidence, survival analysis and associated risk factors.

To evaluate the incidence and survival time for AIDS-patients affected by different stages of nontuberculous mycobacterial (NTM) infection we performed a retrospective study. Data of 1540 hospitalised AIDS-patients was analyzed with respect to survival time and incidence rates. The overall incidence rate of NTM following AIDS was 16.6/100 person-years (PY), with an increase from 12.1/100PY (1987-1990) to 18.9/100PY (1991-1994). Antiretroviral therapy (ART) and toxoplasmosis prophylaxis reduced the risk of NTM disease whereas CD4 cells <40/ microl at time of the first AIDS defining illness led to a 2.5 fold higher risk. Pneumocystis carinii pneumonia (PCP), wasting syndrome and PCP prophylaxis increased the risk of progression from colonization to dissemination. Cryptococcus neoformans infection, wasting syndrome, PCP prophylaxis and CD4 cells <40/ microl were linked to immediate NTM dissemination. Though the incidence of NTM dissemination increased by the factor 1.56 in 1991-1994, survival did not differ between patients with and without NTM infection.