title: Strains of Mycobacterium tuberculosis differ in affinity for human osteoblasts and alveolar cells in vitro.
abstract: Although the lung is the primary site of infection of tuberculosis, Mycobacterium tuberculosis is capable of causing infection at other sites. In 5-10 % such extra-pulmonary tuberculosis is located in bone tissue of the spine. It is unknown whether host or microbial factors are responsible for the site where extra-pulmonary tuberculosis manifests itself. One MDR isolate belonging to strain F28, one susceptible F11 and one isolate each of susceptible, MDR and XDR F15/LAM4/KZN were cultured in Middlebrook 7H9 media. Human osteoblasts (SaOS-2) and human alveolar epithelial cells (A549) were exposed to these different isolates of M. tuberculosis and invasion capacity and intra-cellular multiplication rates were established. Mouse macrophage (MHS) cells exposed to M. tuberculosis H37Rv served as control. The invasion capacity of F15/LAM4/KZN representatives increased with the level of resistance. The F28 MDR strain showed similar invasion capacity as the XDR F15/LAM4/KZN for pulmonary epthelial cells, whilst the fully susceptible F11 strain displayed a propensity for osteoblasts. The differences observed may in part explain why certain strains are able to cause infection at specific extra-pulmonary sites. We postulated that the development of extra-pulmonary tuberculosis depends on the ability of the microbe to pass effectively through the alveolar epithelial lining and its affinity for cells other than those in pulmonary tissue.
authors.affiliation: Department of Infection Prevention and Control, Nelson R Mandela School of Medicine, School of Laboratory Medicine and Medical Science, College of Health Science, University of KwaZulu-Natal, 719 Umbilo Road, Durban, 4075 South Africa.
authors.forename: Shrabanti
authors.initials: S
authors.lastname: Sarkar
authors.affiliation: Department of Infection Prevention and Control, Nelson R Mandela School of Medicine, School of Laboratory Medicine and Medical Science, College of Health Science, University of KwaZulu-Natal, 719 Umbilo Road, Durban, 4075 South Africa.
authors.forename: Muyalo G
authors.initials: MG
authors.lastname: Dlamini
authors.affiliation: Department of Infection Prevention and Control, Nelson R Mandela School of Medicine, School of Laboratory Medicine and Medical Science, College of Health Science, University of KwaZulu-Natal, 719 Umbilo Road, Durban, 4075 South Africa.
authors.forename: Debapriya
authors.initials: D
authors.lastname: Bhattacharya
authors.affiliation: Department of Infection Prevention and Control, Nelson R Mandela School of Medicine, School of Laboratory Medicine and Medical Science, College of Health Science, University of KwaZulu-Natal, 719 Umbilo Road, Durban, 4075 South Africa.
authors.forename: Olubisi T
authors.initials: OT
authors.lastname: Ashiru
authors.affiliation: Department of Infection Prevention and Control, Nelson R Mandela School of Medicine, School of Laboratory Medicine and Medical Science, College of Health Science, University of KwaZulu-Natal, 719 Umbilo Road, Durban, 4075 South Africa.
authors.forename: A Willem
authors.initials: AW
authors.lastname: Sturm
authors.affiliation: Department of Infection Prevention and Control, Nelson R Mandela School of Medicine, School of Laboratory Medicine and Medical Science, College of Health Science, University of KwaZulu-Natal, 719 Umbilo Road, Durban, 4075 South Africa.
authors.forename: Prashini
authors.initials: P
authors.lastname: Moodley
keywords: Extra-pulmonary tuberculosis; Human alveolar epithelial cells (A549); Human osteoblasts (SaOS-2); Mycobacterium tuberculosis; XDR F15/LAM4/KZN