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Detection of natural infection with Mycobacterium intracellulare in healthy wild-caught Chacma baboons (Papio ursinus) by ESAT-6 and CFP-10 IFN-gamma ELISPOT tests following a tuberculosis outbreak.

Chege GK, Warren RM, Gey van Pittius NC, Burgers WA, Wilkinson RJ, Shephard EG, Williamson AL - BMC Microbiol. (2008)

Bottom Line: Screening of mycobacterial infections in NHP is traditionally done by tuberculin skin test (TST), which is unable to distinguish between pathogenic and non-pathogenic mycobacterial infections.This assay performed better than the TST, which failed to detect one M. tuberculosis and two early M. intracellulare infections.There is some doubt, however, concerning specificity, as the assay scored positive three animals infected with M. intracellulare.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Clinical Laboratory Sciences, Faculty of Health Sciences, University of Cape Town, Anzio Road, Observatory 7925, Cape Town, South Africa. Gerald.Chege@uct.ac.za

ABSTRACT

Background: Both tuberculous and non-tuberculous mycobacteria can cause infection in nonhuman primates (NHP), indicating the existence of potential zoonotic transmission between these animals and visitors to zoos or animal handlers in primate facilities. Screening of mycobacterial infections in NHP is traditionally done by tuberculin skin test (TST), which is unable to distinguish between pathogenic and non-pathogenic mycobacterial infections. In this study, we investigated the use of ESAT-6 and CFP-10 for detection of mycobacterial infections in a wild-caught baboon colony after one baboon died of tuberculosis (TB).

Methods: Peripheral blood lymphocytes for interferon-gamma enzyme-linked immunospot assay (IFN-gamma ELISPOT) assay were obtained from TST positive baboons and those in contact with tuberculous baboons before being euthanased, autopsied and lung tissues taken for histology and mycobacterial culture.

Results: Both ESAT-6 and CFP-10 IFN-gamma ELISPOT assays were able to detect early M. tuberculosis but also M. intracellulare infection. Although this indicates potential cross-reactivity with M. intracellulare antigens, the method was able to distinguish M. bovis BCG vaccination from M. tuberculosis infection. This assay performed better than the TST, which failed to detect one M. tuberculosis and two early M. intracellulare infections.

Conclusion: These results suggest that the IFN-gamma ELISPOT assay could improve the detection of M tuberculosis infections when screening NHP. There is some doubt, however, concerning specificity, as the assay scored positive three animals infected with M. intracellulare.

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Related in: MedlinePlus

Summary of the TST, ESAT-6 and CFP-10 IFN-γ ELISPOT assay and mycobacterial culture outcome. A flow diagram showing the outcome of tuberculin skin test (TST), ESAT-6 and CFP-10 IFN-γ ELISPOT assay and mycobacterial culture.
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Figure 1: Summary of the TST, ESAT-6 and CFP-10 IFN-γ ELISPOT assay and mycobacterial culture outcome. A flow diagram showing the outcome of tuberculin skin test (TST), ESAT-6 and CFP-10 IFN-γ ELISPOT assay and mycobacterial culture.

Mentions: Following the death of one baboon (B662) due to pulmonary TB diagnosed at necropsy, the remaining 89 baboons in the colony were screened for mycobacterial infection using bovine PPD tuberculin. Initially, only eight baboons tested positive, including three (B454, B536 & B548) with known prior vaccination with BCG or recombinant BCG. One additional baboon (B369) tested positive three months after initially testing negative, resulting in a total of nine tuberculin reactors (Figure 1 and Table 1). The test reaction ranged from severe (drooping of the eyelid, necrosis of the palpebrum with eyelid completely closed; B524, B531 & B629) to slight reactions (erythema of palpebrum with minimal swelling; B369, B454, B536 & B548). Reactions on eyelids of baboon B659 and B697 were moderate (obvious swelling of palpebrum without drooping or necrosis).


Detection of natural infection with Mycobacterium intracellulare in healthy wild-caught Chacma baboons (Papio ursinus) by ESAT-6 and CFP-10 IFN-gamma ELISPOT tests following a tuberculosis outbreak.

Chege GK, Warren RM, Gey van Pittius NC, Burgers WA, Wilkinson RJ, Shephard EG, Williamson AL - BMC Microbiol. (2008)

Summary of the TST, ESAT-6 and CFP-10 IFN-γ ELISPOT assay and mycobacterial culture outcome. A flow diagram showing the outcome of tuberculin skin test (TST), ESAT-6 and CFP-10 IFN-γ ELISPOT assay and mycobacterial culture.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2275275&req=5

Figure 1: Summary of the TST, ESAT-6 and CFP-10 IFN-γ ELISPOT assay and mycobacterial culture outcome. A flow diagram showing the outcome of tuberculin skin test (TST), ESAT-6 and CFP-10 IFN-γ ELISPOT assay and mycobacterial culture.
Mentions: Following the death of one baboon (B662) due to pulmonary TB diagnosed at necropsy, the remaining 89 baboons in the colony were screened for mycobacterial infection using bovine PPD tuberculin. Initially, only eight baboons tested positive, including three (B454, B536 & B548) with known prior vaccination with BCG or recombinant BCG. One additional baboon (B369) tested positive three months after initially testing negative, resulting in a total of nine tuberculin reactors (Figure 1 and Table 1). The test reaction ranged from severe (drooping of the eyelid, necrosis of the palpebrum with eyelid completely closed; B524, B531 & B629) to slight reactions (erythema of palpebrum with minimal swelling; B369, B454, B536 & B548). Reactions on eyelids of baboon B659 and B697 were moderate (obvious swelling of palpebrum without drooping or necrosis).

Bottom Line: Screening of mycobacterial infections in NHP is traditionally done by tuberculin skin test (TST), which is unable to distinguish between pathogenic and non-pathogenic mycobacterial infections.This assay performed better than the TST, which failed to detect one M. tuberculosis and two early M. intracellulare infections.There is some doubt, however, concerning specificity, as the assay scored positive three animals infected with M. intracellulare.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Clinical Laboratory Sciences, Faculty of Health Sciences, University of Cape Town, Anzio Road, Observatory 7925, Cape Town, South Africa. Gerald.Chege@uct.ac.za

ABSTRACT

Background: Both tuberculous and non-tuberculous mycobacteria can cause infection in nonhuman primates (NHP), indicating the existence of potential zoonotic transmission between these animals and visitors to zoos or animal handlers in primate facilities. Screening of mycobacterial infections in NHP is traditionally done by tuberculin skin test (TST), which is unable to distinguish between pathogenic and non-pathogenic mycobacterial infections. In this study, we investigated the use of ESAT-6 and CFP-10 for detection of mycobacterial infections in a wild-caught baboon colony after one baboon died of tuberculosis (TB).

Methods: Peripheral blood lymphocytes for interferon-gamma enzyme-linked immunospot assay (IFN-gamma ELISPOT) assay were obtained from TST positive baboons and those in contact with tuberculous baboons before being euthanased, autopsied and lung tissues taken for histology and mycobacterial culture.

Results: Both ESAT-6 and CFP-10 IFN-gamma ELISPOT assays were able to detect early M. tuberculosis but also M. intracellulare infection. Although this indicates potential cross-reactivity with M. intracellulare antigens, the method was able to distinguish M. bovis BCG vaccination from M. tuberculosis infection. This assay performed better than the TST, which failed to detect one M. tuberculosis and two early M. intracellulare infections.

Conclusion: These results suggest that the IFN-gamma ELISPOT assay could improve the detection of M tuberculosis infections when screening NHP. There is some doubt, however, concerning specificity, as the assay scored positive three animals infected with M. intracellulare.

Show MeSH
Related in: MedlinePlus