Formation of Mycobacterium abscessus colonies in cellular culture in an in vitro infection model.

Mycobacterium abscessus is one of the most important nontuberculous mycobacteria that cause lung diseases. In vitro infection models developed to analyze the immune response are frequently based on the addition of mycobacteria to mononuclear cells or neutrophils from peripheral blood. An important requirement of these assays is that most cells phagocytose mycobacteria, only accomplished by using large multiplicities of infection (1 or more bacteria per cell) which may not adequately reflect the inhalation of a few mycobacteria by the host. We propose modifications that try to mimic some of the conditions in which immune cells deal with mycobacteria. For the preparation of the inoculum mycobacteria are grown in solid media followed by preparation to a single cell suspension. Multiplicities of infection (number of bacteria per cell) are below 0.01. Serum-free cellular media is used to allow the growth of M. abscessus. After several days of incubation Bacterial Colonies in Cellular Culture (BCCC) develop, which are enumerated directly under an inverted microscope. These colonies may represent biofilm formation during chronic infections. •Low multiplicity of infection (below 0.01 bacteria per cell) reflects more realistically conditions encountered by immune cells in the lungs.•The surface of mycobacteria prepared for infection assays that are grown in solid media are less affected than that of mycobacteria grown in liquid media with detergents.•Colony formation in the infected cells may reflect the aggregation and biofilm formation in the lungs during chronic infection.

Mycobacterium abscessus Infected Neutrophils as an In Vitro Model for Bronchiectasis. Neutrophils Prevent Mycobacterial Aggregation

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A strategy based on Amplified Fragment Length Polymorphism (AFLP) for routine genotyping of nontuberculous mycobacteria at the clinical laboratory.

The increasing worldwide incidence of mycobacteriosis and the need to achieve improved clinical management makes nontuberculous mycobacteria (NTM) genotyping a useful tool. However, because of technical difficulties, medium size microbiology laboratories do not attempt to compare the genetic patterns that each of their isolates present. We have aimed to optimize a genotyping method with a reduced hands-on experimental time and that requires few technical resources. A strategy based on the Amplified Fragment Length Polymorphism (AFLP) methodology was developed using two rare-cutters enzymes (SacI and BglII). One out of seven primers was sequentially used in each amplification reaction that was analyzed by agarose gel electrophoresis. This approach makes it possible the timely genotyping of a moderate number of strains and its characterization without the need of image analysis software. We have genotyped 28 Mycobacterium intracellulare and 4 M. abscessus. Clinical researchers are encouraged to routinely genotype their NTM isolates.

Síndrome de Lady Windermere en Castilla y León / Lady Windermere syndrome in Castile and León

INTRODUCCIÓN: El síndrome de Lady Windermere (SLW) es una patología pulmonar causada por Mycobacterium avium complex (MAC). El objetivo es conocer su frecuencia y sus características en el área norte de la comunidad de Castilla y León. MÉTODOS: Estudio retrospectivo de pacientes con aislamientos de MAC en muestras respiratorias de cinco hospitales públicos de la comunidad a lo largo de seis años, siguiendo criterios de la ATS/IDSA. Las cepas de MAC se identificaron por sondas de hibridación inversa Genotype Mycobacterium o PCR-RFLP del gen hsp65. RESULTADOS: De 183 casos de MAC identificados, únicamente 5 (2,7%) mujeres de 68,8 ± 10,7 años cumplían criterios de SLW. En tres casos se aisló MAC conjunta e intermitentemente con otros patógenos. Solo un paciente se trató siguiendo criterios de la ATS/IDSA. DISCUSIÓN: El SLW permanece infraestimado, y al ser los afectados muy demandantes de recursos sanitarios durante largos periodos, es necesario un mayor conocimiento microbiológico y terapéutico

INTRODUCTION: Lady Windermere syndrome (LWS) is a pulmonary disease caused by Mycobacterium avium complex (MAC). The objective of this study is to ascertain its frequency and characteristics in the northern area of the autonomous community of Castile and León. METHODS: A retrospective study of patients with MAC isolates in respiratory samples from five public hospitals in the autonomous community over a six-year period, following the ATS/IDSA criteria. The MAC strains were identified by GenoType Mycobacterium reverse hybridisation probes or PCR-RFLP analysis of the hsp65 gene. RESULTS: Of 183 cases of MAC identified, only five women (2.7 %) aged 68.8± 10.7 years met LWS criteria. In three cases, MAC was isolated jointly and intermittently with other pathogens. Only one patient was treated according to ATS/IDSA criteria. DISCUSSION: LWS remains underestimated, with affected patients representing a significant burden on healthcare resources over long periods of time. As a result, greater microbiological and therapeutic knowledge of the syndrome is needed

Lady Windermere syndrome in Castile and León. / Síndrome de Lady Windermere en Castilla y León.

INTRODUCTION: Lady Windermere syndrome (LWS) is a pulmonary disease caused by Mycobacterium avium complex (MAC). The objective of this study is to ascertain its frequency and characteristics in the northern area of the autonomous community of Castile and León. METHODS: A retrospective study of patients with MAC isolates in respiratory samples from five public hospitals in the autonomous community over a six-year period, following the ATS/IDSA criteria. The MAC strains were identified by GenoType Mycobacterium reverse hybridisation probes or PCR-RFLP analysis of the hsp65 gene. RESULTS: Of 183 cases of MAC identified, only five women (2.7%) aged 68.8±10.7years met LWS criteria. In three cases, MAC was isolated jointly and intermittently with other pathogens. Only one patient was treated according to ATS/IDSA criteria. DISCUSSION: LWS remains underestimated, with affected patients representing a significant burden on healthcare resources over long periods of time. As a result, greater microbiological and therapeutic knowledge of the syndrome is needed.

Blood antimicrobial activity varies against different Mycobacterium spp.

In vitro analysis of mycobacterial pathogenicity or host susceptibility has traditionally relied on the infection of macrophages, the target cell of mycobacteria, despite difficulties reproducing their antimycobacterial activity. We have employed alternative models, namely whole blood and leukocytes in plasma, from QuantiFERON negative individuals, and performed infections with the pathogenic M. tuberculosis, the less pathogenic M. avium, M. kansasii and M. chelonae and the occasionally pathogenic M. gordonae and M. bovis. The anticoagulant used in blood extraction, heparin or EDTA, had a major influence in the outcome of the infection. Thus, while in the heparinized models a similar number of bacteria were enumerated in the inoculum and after seven days, in the presence of EDTA a killing effect was observed, despite the inhibitory effect of EDTA on cellular functions like the production of cytokines or reactive oxygen species (ROS). A special case was the rapidly growing mycobacteria M. chelonae, that multiplied in heparinized models but was eliminated in models with EDTA. We verified that EDTA is not responsible for the bactericidal effect, but acts as a bacteriostatic agent. Further work will determine whether blood derived models are a better alternative to the classical macrophage.

Plasma contributes to the antimicrobial activity of whole blood against Mycobacterium tuberculosis.

The whole blood model for infection has proven useful to analyze the immunological response to Mycobacterium tuberculosis, because it exerts a significant antimicrobial activity. Although this activity has been generally assumed to be cellular, we have found that the leukocyte fraction of blood from healthy volunteers did not kill the bacilli. We have discovered that plasma was responsible for a large proportion, but not all, of the antimicrobial activity. Furthermore, infected monocytes controlled the mycobacterial multiplication when cultivated in the presence of plasma. Intriguingly, serum from the same donors did not share this activity, although it was able to eliminate the non-pathogenic Mycobacterium gordonae To identify the remaining components that participate in the antimycobacterial activity we fractionated blood in leukocytes, plasma, erythrocytes and platelets, and analyzed the bactericidal power of each fraction and their combinations using a factorial design. We found that erythrocytes, but not platelets, participated and showed by flow cytometry that mycobacteria physically associated with erythrocytes. We propose that in exposed healthy individuals that show 'early clearance' of the mycobacteria, the innate response is predominantly humoral, probably through the effect of antimicrobial peptides and proteins.