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.

THANK YOU