MDR-TB

[kent nickell]

The WHO together with the South African Medical Assn and the Norwegian Medical Assn has produced a free of charge web based self-learning program on Multi Drug Resistant Tuberculosis including treatment guidelines which can be found at http://lupin-nma.net/index.cfm?m=2&s=1&kursid=126&file=kurs/K126/intro.cfm It is in English but will soon be translated into French, Spanish, Chinese and Russian...

 

[kent nickell]

Re: MDR-TB

This appears to be the currently accepted definition of XDR-TB. It appears to reflect clinical experience and limitations to drug sensitivity testing.... It is an extension of MDR-TB which is resistance to the first line drugs isoniazid and rifampin...

http://jama.ama-assn.org/cgi/content/full/296/23/2792

JAMA Vol. 296 No. 23, December 20, 2006

From the Centers for Disease Control and Prevention: Morbidity and Mortality Weekly Report

Notice to Readers: Revised Definition of Extensively Drug-Resistant Tuberculosis

JAMA. 2006;296:2792.
MMWR. 2006;55:1176

In a report published on March 24, 2006, MMWR reported that CDC, incollaboration with the World Health Organization (WHO) and participating supranational reference laboratories, had agreed to define extensively drug-resistant tuberculosis (XDR TB) as cases of TB disease in persons whose Mycobacterium tuberculosis isolates were resistant to isoniazid and rifampin and at least three of the six main classes of second-line drugs (aminoglycosides, polypeptides, fluoroquinolones, thioamides, cycloserine, and para-aminosalicyclic acid).1

Since that original publication, additional reports have documented the presence of XDR TB in Iran and South Africa with high mortality among persons infected with human immunodeficiency virus (HIV) who are benefiting from antiretroviral therapy.2-3

The emergence and transmission of these strains of M. tuberculosis highlight the urgency of strengthening national TB and HIV/acquired immunodeficiency syndrome control programs worldwide, particularly in settings with high HIV prevalence. CDC is collaborating with national and international health agencies to provide leadership, technical support, and capacity building to ensure proper action is taken to limit the development and spread of XDR TB. An initial consultation was convened by the South Africa Medical Research Council in Johannesburg, South Africa, during September 6-7, 2006. A seven-point emergency action plan to combat XDR TB was issued by agencies represented at this meeting (additional information is available at http://www.mrc.ac.za/pressreleases/8pres2006.htm).

Subsequently, WHO organized the first meeting of the Global XDR TB Task Force, held in Geneva, Switzerland, during October 8-9, 2006. This meeting was called by WHO to develop a rapid response to the emerging problem of XDR TB.

As a result of the meeting, participants agreed upon a revised case definition of XDR TB. According to laboratory professionals in attendance, drug-susceptibility testing to fluoroquinolones and second-line injectable drugs (i.e., amikacin [aminoglycoside], kanamycin [aminoglycoside], or capreomycin [polypeptide]) yields reproducible and reliable results, whereas drug-susceptibility testing to other second-line drugs is less reliable. Additionally, investigators have observed that resistance to these drugs (fluoroquinolones and second-line injectable drugs) has been associated with poor treatment outcomes.

Accordingly, the new agreed-upon definition of XDR TB is the occurrence of TB in persons whose M. tuberculosis isolates are resistant to isoniazid and rifampin plus resistant to any fluoroquinolone and at least one of three injectable second-line drugs (i.e., amikacin, kanamycin, or capreomycin).

Health-care providers and local health departments in the United States should collect all second-line drug-susceptibility results obtained at diagnosis and during treatment of persons with TB disease and report these results to their local and state health department TB programs. Complete capture of these results will allow health departments and CDC to accurately identify XDR TB cases and monitor trends. Additional information about XDR TB is available at http://www.who.int/tb/en.

REFERENCES
1. CDC. Emergence of Mycobacterium tuberculosis with extensive resistance to second-line drugs?worldwide, 2000-2004. MMWR. 2006;55:301-305. PUBMED\
2. Masjedi MR, Farnia P, Sorooch S, et al. Extensively drug-resistant tuberculosis: 2 years of surveillance in Iran. Clin Infect Dis. 2006;43:841-847. FULL TEXT | PUBME
3. Gandhi NR, Moll A, Sturm AW, et al. Extensively drug-resistant tuberculosis as a cause of death in patients co-infected with tuberculosis and HIV in a rural area of South Africa. Lancet. 2006;(October):26 http://www.thelancet.com/journals/lancet/article/PIIS0140673606695731. Online.

 

[kent nickell]

Re: MDR-TB

A few points from this course... MDR-TB (and this is not as bad as XDR-TB) is 100 times more expensive to treat than drug susceptible TB...

Over a third of all fatalities among HIV-positive people include patients with TB. If TB is not treated properly, drug-resistant TB can spread quickly among other HIV-positive individuals, health workers and hospital visitors.

 

[kent nickell]

Re: MDR-TB

The last chapter in this course is on TB in prisons which presents special problems. Prisons can be a breeding ground for HIV and MDR and XDR-TB. They are often under Ministries of Interior and Justice with little interaction with Ministries of Health let alone national TB programs. There are often overcrowded conditions with little health screening or treatment. There are 'bridging' populations of people including lawyers, prison staff, family members, repair and sanitation workers etc who interact with prison populations and then return to communities where they can spread any disease they may catch at the prison. Also most prisoners are eventually released back into the community sometimes with a death sentence of MDR or XDR TB which they can spread to family members or community members and they can also migrate across borders. This TB problem does seem to be leading to more public and political concern for prisoner health issues.