Ramiro López-Medrano

Immunological response to Mycobacterium tuberculosis infection in blood from type 2 diabetes patients

The convergence of tuberculosis and diabetes represents a co-epidemic that threatens progress against tuberculosis. We have investigated type 2 diabetes as a risk factor for tuberculosis susceptibility, and have used as experimental model whole blood infected in vitro with Mycobacterium tuberculosis. Blood samples from diabetic patients were found to have a higher absolute neutrophil count that non-diabetic controls, but their immune functionality seemed impaired because they displayed a lower capacity to phagocytose M. tuberculosis, a finding that had been previously reported only for monocytes. In contrast, an increased production of TNFα was detected in infected blood from diabetic patients. Despite the altered phagocytic capacity showed by cells from these patients, the antimicrobial activity measured in both whole blood and monocyte derived macrophages was similar to that of controls. This unexpected result prompts further improvements in the whole blood model to analyze the immune response of diabetes patients to tuberculosis.

Contribución de la microbiología al diagnóstico de la tuberculosis en Castilla y León: conclusiones del estudio GRUMICALE 2013

INTRODUCTION AND OBJECTIVES A retrospective study was conducted by collecting microbiological tuberculosis (TB) data in Castile and León during the year 2013 in order to determine the incidence and distribution of TB, and resistance to the tuberculostatic drug, and compare them with the epidemiological data provided by the Department of Epidemiological Surveillance (SIVE). MATERIAL AND METHODS Microbiologists of the 14 hospitals of the Castile and León public health network (GRUMICALE) collected epidemiological, microbiological, and management data from the Microbiology laboratories in the community during the year 2013. A single isolate of Mycobacterium tuberculosis complex (MTC) per patient was considered. RESULTS The study included a total of 270 MTC isolates (an incidence rate of 11.63 cases/100,000 inhab./year). A total of 288 cases of TB (11.43 cases/100,000 inhab. year) were recovered using epidemiological data, which included 243 confirmed, 29 suspected, and 16 as probable cases. Pulmonary TB was predominant, followed a long way off by the pleural TB and the remaining locations. A total of 27,620 samples were processed for mycobacterial detection. Mycobacterial growth was observed in 3.46% of automated fluid cultures, and 50.37% were positive by direct staining of the smear. Resistance to one tuberculostatic drug, mostly to isoniazid, was observed in 16 (5.92%) isolates of Mycobacterium tuberculosis (MT). The province with greater incidence and number of isolates was León (24.23 cases/100,000 inhab./year), with the highest being observed in El Bierzo health area (30.46 cases/100,000 inhab./year). CONCLUSIONS An adequate collection of microbiological information is essential to determine the epidemiology of TB in our region.

In vitro infection with Mycobacterium tuberculosis induces a distinct immunological pattern in blood from healthy relatives of tuberculosis patients

Part of the susceptibility to tuberculosis has a genetic basis, which is clear in primary immunodeficiencies, but is less evident in apparently immunocompetent subjects. Immune responses were analysed in blood samples from tuberculosis patients and their healthy first-degree relatives who were infected in vitro with mycobacteria (either Mycobacterium tuberculosis or M. bovis BCG). The antimicrobial activity against M. tuberculosis in blood from relatives was significantly lower than that observed in healthy controls. Tuberculosis patients exhibited a higher number of neutrophils, and monocyte phagocytosis was inhibited in both relatives and tuberculosis patients. A remarkable finding was that the production of reactive oxygen species by infected neutrophils was higher in relatives than in healthy controls. A higher production of TNFα in infected blood from relatives was also observed. These results may indicate that relatives display a stronger inflammatory response and that their immune response to M. tuberculosis is different from those of unrelated controls. First-degree relatives may represent a highly informative group for the analysis of tuberculosis susceptibility.