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DRUG RESISTANCE IN TUBERCULOSIS:Causes

Drug resistant bacilli are the consequence of human error in any of the following

  • Prescription of chemotherapy
  • Management of drug supply
  • Case management
  • Process of drug delivery to the patient
The most common medical errors are the following :
  • the prescription of inadequate therapy to the multibacillary pulmonary tuberculosis cases o(e.g only 2 or 3 drugs during the initial phase of treatment in a new smear positive patient with bacilli initially resistant to isoniazid).It is important to give 3 or more drugs during the initial phase because mutants resistant to drug a(eg Isoniazid)are killed by drug B(eg Rifampicin).In addition because the mutations occur at a low frequency it is highly improbable that a single organism would evolve spontaneous resistance to both organisms.
  • Failure to impress upon the patient the need to take all  the prescribed drugs.Some patients may omit one or more drugs either because of ignorance or some misconceived notions regarding toxicity.The directly observed chemotherapy avoids this error.
  • The addition of single drug to a failing regimen because if failure were due to drug resistant,the bacillary population is vulnerable to the acquisition of further resistance,in this manner the strains may become sequentially resistant to several agents
The most common errors observed in the management of drug supply are the following :
  1. the difficulty experienced by the poor patients in obtaining all the drugs they need
  2. frequent or prolonged shortages of antitubercular drugs(due to financial constraints and or poor management in stock replenishment in developing countries
  3. use of drugs (or combinations of unproven bioavailability)
Introduction | Criteria of MDR TB | Causes | Prevention | Management | Dosage and side effects

Disclaimer Altough every precaution has been taken in the preparation of this site,the author assumes no responsiblity for errors or omisssions.Neither is any liability assumed for damages resulting from the use of the information contained herein
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