From discussions with colleagues, I get the impression that a single TB infection involves a single strain. This cannot be unless there is a preventive mechanism that renders the acquisition of another Mtb strain by the already infected person. Years ago I began to look into this question with specimen received from a Portuguese prison whose inmates share cells. Many of these inmates acquire the infection in prison and it seems that the opportunity to acquire another infecting organism is present. What are your thoughts or ideas on this topic?
I think the possibility of getting different Mtb strains infection is still standing that what i noticed after collecting blood samples from patients and there contacts to start tracing using different molecular and gene level methods and always there is different strains even u reached the single source strain patient .
Infection with multiple strains can happen as documented by Braden (1) and colleagues. What is unknown is how often this happens. Exposure to a second strain of Mtb must be relatively common in endemic areas and prior exposure does not result in immunity (see 2), so concurrent infection with two strains may be surprisingly common.
(1) Braden CR, Morlock GP, Woodley CL, Johnson KR, Colombel AC, Cave MD, et al. Simultaneous infection with multiple strains of Mycobacterium tuberculosis. Clin. Infect. Dis. 2001 Sep 15;33(6):e42–7.
(2) van Rie A, Warren R, Richardson M, Victor TC, Gie RP, Enarson DA, et al. Exogenous reinfection as a cause of recurrent tuberculosis after curative treatment. N. Engl. J. Med. 1999 Oct 14;341(16):1174–9.
The cited paper refers to a second infection following cure. I am speaking of two strains infecting the same host at the same time.
Dear Len,
Sabine Thiel wrote an interesting ERJ paper with my group that shows that in Uzbekistan, some patients clearly have multiple (Beijing) strains infecting them at the same time. Also, with Sahal Al-Hajoj we have described a patient with clonal variants of one strain in different body sites. Hopefully that is of help to you.
Article Microevolution of Mycobacterium tuberculosis in a Tuberculosis Patient
Dear Len,
Hope that you read this, I have described a secondary infection which took place during the hospital stay of one patient (A case of healthcare-associated, multidrug-resistant tuberculosis in Austria: reconsidering the value of cohorting of patients with culture-positive tuberculosis.) I think this happens quite often, but we dont see it since we are used to treat the infection of with the MTC strain having the worst resistance pattern.
Alexander
I face such experience like this, we isolate two Mycobacterium tuberculosis strain from the same patient from Sudan with different susceptibility pattern to isoniazid. Upon intensive molecular typing they appears as two different spoligotypes.
Infection with different strains of M. tuberculosis can occur in the same individual. Many reports have been there in the past. References are as below:
Robin M. Warren, Thomas C. Victor, Elizabeth M. Streicher, Madalene Richardson, Nulda Beyers, Nicolaas C. Gey van Pittius, and Paul D. van Helden "Patients with Active Tuberculosis often Have Different Strains in the Same Sputum Specimen", American Journal of Respiratory and Critical Care Medicine, Vol. 169, No. 5 (2004), pp. 610-614;Mixed-Strain Mycobacterium tuberculosis Infections among Patients Dying in a Hospital in KwaZulu-Natal, South AfricaTed Cohen*, Douglas Wilson, Kristina Wallengren, Elizabeth Y. Samuel and Megan Murray.J. Clin. Microbiol. January 2011 vol. 49 no. 1 385-388
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