Mycobacteria are opportunistic pathogens. Some cases of pulmonary mycobacteriosis were recently notified in some hospitals where immunodepressed subjects were present. It could be important to get the infective dose for assessing the risk.
Probably yes in some cases, but the biological consequence of infection also depends on the otherside of the question, on the actual immun status of the intected individual.
you are on the right track,bymentioning the dimmunosuppression. The level ofimmunosuppression can be different.
NTM are purely opprotunistic pathogens. For this type of microorganisms infective doses cannot be determined as infections resulting from contacts are influenced by too many cofactors.
Harald is right. The infective dose here is meaningless, as the local (pre-existent pulmonary damage / disease) or systemic impairment of immunity largely determine the chance to develop infection and disease after exposure. It is likely that the bacterial load / inoculum plays a role, but a minor one. In animal models, you could establish an infective dose, but it is unlikely that that can be extrapolated to humans.
for extrapulmonary disease after inoculation (M. marinum skin disease, NTM tenosynovitis after trauma), an infective dose may be calculated; to the best of my knowledge, this has never been done.
Hi Lucia,
an infective dose is very hard to arrive at for a couple of reasons. Firstly the infections are for the most part opportunistic and so dependent on the immune status of the host. Given this is a complex of organisms virulence is very variable between strains and species. MAC cause a variety of different infections which will probably require different routes of transmission and therefore different dose responses. As a result I don't think you will find an infective dose that would be useful in risk assessment.
hope this helps
Cheers,
Richard
They are purely opportunistic disease. The disease is determined by immune staus of the subject and not the dose/ cell counts . There are reported cases where infections had been acquired by patients undergoing open heart surgeries from operation theaters. However, assays to determine relative virulence of the non tuberculous mycobacteria using tissue cultures have been tried. I am not aware if this tests are available or have been further tested.
I deeply appreciate for all your contributions. Thank you very much for your extremely helpful and detailed response to my question !
Best regards
Lucia
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