Question

Why would a dr perform a gram stain on a sample before prescribing an antibiotic?

Answer 1

irst of all, I have yet to witness a physician perform a gram stain. That is normally the job of the medical lab tech. lol 

The Gram stain is indispensable in identifying unknown bacteria. It allows the MLT to determine if the organism is either a Gram (+) rod, Gram (-) rod, a Gram (+) coccus, a Gram (-) coccus or a Gram-nonreactive. 

Gram (+) organisms are more susceptible to Penicillin than Gram (-). 

Determining the Gram reactions of the bacteria helps to facilitate the diagnosis and treatment. 

Gram (+) bacteria include causative organisms of anthrax, rheumatic fever, diphtheria, botulism, etc. 

Gram(-) bacteria are identified as causative agents of cholera, typhoid, dysentery, whooping cough, some food poisonings, bubonic plague, etc. 

Thus, the importance of determining the Gram (+) and the Gram(-) bacteria. This is how the physician will determine the diagnosis and treatment. 

Note: The cell wall is the main factor in deciphering which is Gram (+) or Gram (-) The cell wall with either "take up" the stain readily or will not . This is what differentiates the (+) from the (-). 

The Gram (+) and Gram (-) bacteria will require different certain antibiotics to eradicate the bacteria. Some are susceptible to a particular antibiotic and some are resistant the the same antibiotic. This is how the physician decides which antibiotic to administer or prescribe.