Published Date: 2007-01-25 00:00:00
Subject: PRO/EDR> Tuberculsos, extensively drug-resistant - Canada (ON)(02)
Archive Number: 20070125.0340
TUBERCULOSIS, EXTENSIVELY DRUG-RESISTANT - CANADA (ONTARIO)(02)
A ProMED-mail post
ProMED-mail, a program of the
International Society for Infectious Diseases
Date: Thu, 25 Jan 2007
Source: Frances Jamieson <firstname.lastname@example.org>
As a clarification to the posting from 24 Jan 2007, please note that
Ontario currently has 2 cases of XDR-TB, as defined by the new
definition from WHO of November 2006. There are also MDR-TB cases
with some 2nd-line drug resistance which do not meet the current
XDR-TB case definition. These cases are undergoing appropriate
treatment and follow-up.
Frances B. Jamieson, MD
Public Health Laboratories Branch,
Ontario Ministry of Health and Long-Term Care
[ProMED thanks Dr. Jamieson for the information.
The definition of XDR TB until the fall of 2006 was an isolate of _M.
tuberculosis_ resistant to isoniazid and rifampin and at least 3 of
the 6 main classes of 2nd-line drugs (aminoglycosides, polypeptides,
fluoroquinolones, thioamides, cycloserine, and para-aminosalicyclic
acid) as stated in the MMWR report cited in the comment to the previous post.
After the WHO Report of the meeting of the WHO Global Task Force on
XDR-TB, Geneva, Switzerland, 9-10 Oct 2006, the definition was
modified to: an isolate resistant to INH and rifampin (also called
rifampicin) which was also resistant to a fluoroquinolone and to 1 or
more of the following 3 injectable antituberculosis drugs:
capreomycin, kanamycin and amikacin.
According to the report
number of considerations were used in revising the definition, including:
- technical feasibility and reproducibility of testing for second-line drugs
- efficacy and availability of second line drugs
- the need for a definition with significant worse treatment outcome
than MDR-TB alone. - Mod.LL]