ANTIMICROBIAL DRUG RESISTANCE

 

OBJECTIVES OF THIS ARTICLE:  By the end of this article, the reader will be able to;

1.  Understand the reason some microbes don't die from commonly used antibiotics.

2.  Identify the reasons microbes become resistant to drugs

3.  Predict the possible consequences of irrational drug used especially antibiotics.

INTRODUCTION:  The drugs that are used to treat microbes are termed antibiotics and they are of different classes, types and with varying duration of action and dosage regimens.  With the introduction of antimicrobial agents, it was thought that soon mankind would get rid of the infectious diseases.  But this was not to be.  One of the major factor contributing to the persistence of infectious diseases has been the tremendous capacity of the microorganisms for circumventing the action of inhibitory drugs.  This ability has also offered a serious threat to the future usefulness of present day chemotherapeutic agents.  The basis of drug resistant strains could be genetic or non-genetic.  [ANTIMICROBIAL AGENTS]

ORIGIN OF DRUG RESISTANT STRAINS:  The drug resistant strains arise either by mutation and selection or by genetic exchange in which a sensitive organism receives the genetic material or part of DNA, from the resistant organism and the part of DNA carries with it the information of mode of inducing resistance against one or multiple antimicrobial agents.  The drug resistance can arise by random mutation and when with it the organism becomes resistant to a drug, the application of that drug shall select out the resistant organisms and let them multiply.  [STRUCTURE OF DNA]

TRANSMISSIBLE (INFECTIOUS) DRUG RESISTANCE:  Apart from chromosomal resistance, extrachromosomal material which is called as plasmid (or episome) is also capable of conferring resistance to antibiotics.  There is adequate evidence to suggest that transfer of resistance can occur within the intestinal tract of human beings as well as the animals.

BIOCHEMICAL MECHANISMS OF DRUG RESISTANCE:  The biochemical changes which are seen in bacteria which have become resistant due to mutation are:  

(1)            Increased synthesis of drug antagonist Decreased permeability to drug  

(2)            Increased destruction of inhibitor  

(3)            Induction of different relative affinity of substrate and antagonist. The mechanism of drug resistance induced by plasmids is different than what is seen in mutated organism.

RELATED;

1.  BETA LACTAMASE INHIBITORS

2.  DYNAMICS OF DRUGS AND THE HUMAN BODY

3.  PHARMACOLOGY AND THERAPEUTICS

[REFERENCES]