Published Date: 2009-01-14 03:00:51
Subject: PRO/EDR> Tuberculosis, MDR - China
Archive Number: 20090114.0151
TUBERCULOSIS, MDR - CHINA
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: Sat 10 Jan 2009
Source: Reuters Health [edited]
Levels of drug-resistant tuberculosis (TB) in China are nearly twice the
global average and almost 10 per cent of cases are resistant to the most
effective 1st-line drugs, a study has shown.
China has an estimated 4.5 million cases of people with TB, the 2nd largest
number of TB cases in the world after that of India and is struggling with
high levels of drug-resistant TB, which is costly and difficult to treat.
In a survey involving 10 provinces between 1996 and 2004, researchers found
that multi-drug resistant (MDR) TB made up 9.3 per cent of all cases, 5.4
per cent of new cases, and 25.6 per cent of previously treated cases.
All 3 figures were markedly higher than global MDR-TB figures, which stand
at 4.8 per cent for all cases, 3.1 per cent for new cases, and 19.3 per
cent for previously treated cases, the researchers wrote in the journal BMC
Infectious Diseases [He GX, et al. Prevalence of tuberculosis drug
resistance in 10 provinces of China. BMC Infect Dis 2008; 8: 166; abstract
available at <http://www.biomedcentral.com/1471-2334/8/166>].
Regular TB requires a 6 to 12 months course of treatment, but many patients
tend to give up because of side effects or a careless attitude. But this
comes with a serious risk, as they may develop drug resistance and require
stronger drugs the next time round, which may be too expensive or simply
MDR-TB, which is defined as resistance to 2 of the most potent anti-TB
drugs [isoniazid and rifampin], takes 2 years to treat and is costly. Toxic
and less effective 2nd-line drugs are used and infected patients are less
likely to survive.
With a good TB control program, the proportion of previously treated
patients among all TB patients should be low. But the study found that the
proportion of previously treated patients [?among patients with active
tuberculosis] in China was around 20 per cent, compared to a global average
of 11 per cent.
"Many possible explanations for the development of drug resistance in China
exist, and different explanations may prevail in different areas of this
vast country," the researchers wrote. "These include the inadequate use of
anti-TB drugs in public hospitals, lack of supervision of treatment
[so-called directly observed therapy or DOT], poor drug-management, and
absence of infection control measures in hospitals. Also, availability of
anti-TB drugs without a prescription in some areas of China in the past may
have contributed to the development of drug resistance," they said.
[reporting by Tan Ee Lyn; editing by Valerie Lee]
[MDR-TB and its most dangerous form, extremely drug-resistant TB (XDR-TB),
nowadays are becoming the most serious public health problems. The study
authors concur with what has been previously reported in other parts of the
world, when pointing out the reasons for the greater frequency of MDR-TB in
China. It is urgent to strengthen anti-tuberculous therapy programs and to
make sure patients comply with them [DOTS, DOTS-Plus] in order to improve
the worrying figures presented in this report. - Mod.JG
DOTS stands for directly observed treatment, short course, which consists
of isoniazid (INH), rifampin, pyrazinamide, and ethambutol (or
streptomycin). The course of DOTS is 6 months. DOTS prevents the emergence
of multidrug resistant tuberculosis (MDR-TB) (resistance to both INH and
rifampin) by ensuring that patients adhere to the full course of treatment.
In resource-poor, developing countries, for example, perhaps in rural
China, DOTS may be started on the basis of suggestive symptoms and a
positive microscopic examination of a sputum smear for acid-fast bacilli
Mycobacterial cultures and drug susceptibility testing are not necessarily
required in DOTS, in which case drug resistance will not be detected even
if it is present. Patients with MDR-TB would not be expected to respond to
such therapy and continue to spread MDR-TB in the population. The study on
which the news release above was based emphasized the importance of having
quality-assured laboratories available for culture and drug susceptibility
DOTS-Plus stands for directly observed treatment in the presence of MDR, in
which a combination of 2nd-line antituberculosis drugs is used for 18 to 24
months. The regimen should include 2 or more drugs to which the isolate is
susceptible in an attempt to present emergence of further drug resistance.
2nd-line drugs are more toxic and expensive, and less effective, than
1st-line drugs that are used in DOTS. The DOTS-Plus regimen is either:
individualized according to drug susceptibility test results of the _M.
tuberculosis_ isolate identified on culture; or given as a standardized
empiric regimen when culture and drug susceptibility testing is not
available to patients suspected of having MDR-TB
pilot projects are only recommended in settings where the DOTS strategy is
fully in place (<http://www.tbcindia.org/pdfs/DOTS-Plus%20Guidelines.pdf>).