[afro-nets] Reinfection "the main cause" of drug resistant TB

[Leela McCullough <leela@healthnet.org>]

Reinfection "the main cause" of drug resistant TB
-------------------------------------------------

Talent Ngandwe
23 February 2007

Source: SciDev.Net
http://www.scidev.net/News/index.cfm?fuseaction=readNews&itemid=3439&language=1

A major shift in TB control strategies could be necessary
following a Shanghai study that found that most cases of drug-
resistant tuberculosis were caused, not by poor treatment
regimes, but by patients being reinfected with a different drug-
resistant strain.

The discovery counters current thinking that the tuberculosis
(TB) bacteria mutates to become drug resistant and suggests that
new strategies for controlling the disease are needed.

Qian Gao of Shanghai Medical School and colleagues from Shanghai
Municipal Centre for Disease Control and Prevention, looked at a
group of 32 patients with drug resistant TB.

To assess the level of drug susceptibility, they analysed the
genetic makeup of Mycobacterium tuberculosis the bacteria that
causes the disease in patient samples over five years.

They discovered that in the majority of patients, samples taken
at the beginning of treatment and during treatment had different
genetic makeups, showing that new strains of M.tuberculosis had
infected the patients, rather than an existing strain having
mutated.

The results show that the assumption that poor treatment
adherence usually causes drug resistance is false, Gao told
SciDev.Net.

He said this might drive a major shift in strategy for
controlling TB.

Multidrug-resistant TB affects over a quarter of treated TB
patients in China, where some 1.3 million people are diagnosed
every year.

Resistance to drugs can also build up when the initial infecting
strain mutates as a result of inappropriately prescribed drugs,
or patients fail to follow treatment regimes.

The study is published in the March issue of The Journal of
Infectious Diseases.
Link to full paper in The Journal of Infectious Diseases:
http://www.journals.uchicago.edu/JID/journal/issues/v195n6/37266/37266.html

Reference: The Journal of Infectious Diseases 195, 864 (2007)

--
Leela McCullough, Ed.D.
Director of Information Services
AED-SATELLIFE Center for Health Information and Technology
30 California Street, Watertown, MA 02472, USA
Tel: +1-617-926-9400
Fax: +1-617-926-1212
mailto:lmccullough@aed.org
http://www.healthnet.org