Download - MDR TB
HARIKRISHNAN. M2010 MBBS
MDR TB
DEFINITION
MDR TB: TB caused by a strain of M. tuberculosis that is resistant to both isoniazid and rifampicin.
Why INH and Rifampin
Most potent and bactericidal.Mono-resistance to one of them can be
treated effectively with a regimen containing the other agent with very low failure rate (2.5-5%)
Failure rate when INH + Rifampicin resistant is 44% in non-HIV and 70% in HIV patients
Duration required for cure doubles to triples.
EPIDEMIOLOGY
STATISTICS -INDIA
Estimates of MDR-TB burden 2012
New Retreatment
% of TB cases with MDR-TB
2.2(1.9-2.6) 15(11-19)
MDR –TB cases among notified pulmonary 21000(18000-25000) 43000 (32000-54000) TB cases
Reported cases of MDR TB 2012
Total
Cases tested for MDR TB 55611
Laboratory confirmed MDR TB cases
16588
Patients started on MDR TB treatment
14143
MDR SUSPECT
Category I failuresCategory II patients who are smear positive
at 4 months or later.Contacts of MDR cases who are found to be
smear positive.(2009)
DIAGNOSIS
MDR-TB is not clinically distinguishable from drug-susceptible TB at the outset.
Signs, symptoms, and radiological findings are similar initially to drug-susceptible TB.
Sputum culture
DST(Drug Susceptibility Testing) –
definitive diagnosis of drug resistant TB.
2 methods Phenotypic and Genotypic
Phenotypic method- culturing of M. tuberculosis in the presence of anti TB drugs to detect growth (indicating drug resistance) or inhibition of growth (indicating drug susceptibility)
Phenotype DST methods are performed as direct or indirect tests on solid or liquid media.
And among them Indirect phenotype test is extensively validated and are currently regarded as GOLD STANDARD.
Genotypic method- targets specific molecular mutations associated with resistance against individual drugs.
Moleular testing allows rapid detection of resistance to rifampicin( alone or in combination with isoniazid). It provides DST results within one day.
Catridge based nucleic acid amplification test(NAAT) –very high sensitivity.
TREATMENT
Difficult.WHO recommends DOTS PLUS guidelines
initiated by PMDT (Programmatic Management of Drug Resistant TB)
After diagnosis treatment of MDR TB is initiated at designated DOTS Plus sites which are established in tertiary care centres ( like medical colleges, large speciality hospitals).
DOTS PLUS
Treatment regime : 6 (9) months - kanamycin ofloxacin ethionamide cycloserine pyrazinamide ethambutol
18 months –Ofloxacin Ethionamide cycloserine ethambutol
Follow up: Smear examination should be conducted
monthly during intensive phase and atleast quarterly during continuation phase.
Culture examination should be done atleast at 4,6,12, 18 and 24 months of treatment.
Treatment adherence : patient and family members counselled prior to treatment initiation and during follow up visits.
Efforts should be made to administer treatment under DOTS over entire period of treatment.
Documentation of treatment : Systemic record of treatment, regimen, doses, duration, side effects, investigation results and treatment outcome for all patients initiated on second line treatment should be maintained.
2009 DOTS PLUS policy
Defn of MDR suspect revised to include ‘contacts of MDR cases who are found to be smear positive’ besides Cat I failures and Cat II patients who are smear positive at 4 months or later.
The existing exclusion criteria for MDR suspects i.e. age <15 years and history of intake of 2nd line drugs for more than 1 month in the past has been withdrawn. A new weight band (16-25 kgs) has been added for the treatment of pediatric MDR patients.
Inorder to make the Cat IV regimen more effective it has been decided to replace Ofloxacin with Levofloxacin.
Guidelines for management of MDR patients with pregnancy has been finalised.
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