Lung infections as well as lymphadenitis are most often caused by M. NTM cause skin infections, lung diseases, lymphadenitis and disseminated disease mostly in immuno-compromised persons. While the incidence of tuberculosis is declining in the developed world, infection rates by NTM are increasing. Remarkably, NTM are resistant to amoeba and protected against adverse conditions inside amoebal cysts. They are ubiquitous and have been isolated from soil, natural water sources, tap water, biofilms, aerosols, dust and sawdust. tuberculosis as well as environmental opportunistic bacteria called NTM. The genus Mycobacterium ( M.) comprises highly pathogenic bacteria such as M. By this method, four new MAH genes were identified that may be involved in virulence. We established a random mutagenesis method for MAH that can be easily carried out and combined it with a set of phenotypic screening methods for the identification of virulence-associated mutants. The mutated genes were MAV_4334 (nitroreductase family protein), MAV_5106 (phosphoenolpyruvate carboxykinase), MAV_1778 (GTP-binding protein LepA) and MAV_3128 (lysyl-tRNA synthetase LysS). Out of 50 randomly chosen Hygromycin-resistant colonies, four revealed to be affected in virulence-related traits. Screening for mutations possibly affecting virulence was performed by monitoring of pH resistance, colony morphology, cytokine induction in infected macrophages and intracellular persistence. We developed a random mutagenesis method based on illegitimate recombination and integration of a Hygromycin-resistance marker. avium and identification of virulence-associated genes are therefore needed. More efforts in developing new methods for mutagenesis of M. avium have been defined among other things due to difficulties in generating M. hominissuis (MAH), which is considered to be among the clinically most important NTM. NTM are ubiquitous and have been isolated from soil, natural water sources, tap water, biofilms, aerosols, dust and sawdust. tuberculosis as well as environmental opportunistic bacteria called non-tuberculous mycobacteria (NTM).
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