What Are Gram Negative Antibiotics?

Mary McMahon
Mary McMahon

Gram negative antibiotics are medications effective against infections with Gram negative bacteria like Escherichia coli. These infections can be difficult to treat, as the bacteria resist many common antibiotics, and rather than being treatable with a broad spectrum drug, it may be necessary to use a very specific formulation. This requires the doctor to conduct tests to find out which organism is causing the infection, rather than providing the patient with a basic antibiotic in the hopes that it will work.

Gram negative antibiotics may be administered to treat E. coli.
Gram negative antibiotics may be administered to treat E. coli.

The distinction between Gram negative and Gram positive bacteria depends on how they perform in a Gram stain, a laboratory test where a technician exposes the cells to crystal violet and then counterwashes them to see if they retain color. If the bacteria stain, they are Gram positive. Gram negative bacteria do not stain because of differences in the structure of their cell walls. These differences prove to be key to determining what kinds of antibiotics the organisms respond to. Gram positive organisms are more susceptible to antibiotics in general and are often treatable with broad spectrum drugs.

Bacteria associated with urinary tract infections are often Gram negative.
Bacteria associated with urinary tract infections are often Gram negative.

Designers of Gram negative antibiotics must develop drugs capable of punching through the cell membrane of Gram negative bacteria to deliver lethal medications to the organism, and each cell wall is different, making this challenging. The drugs may interfere with cell wall synthesis, bacterial reproduction, or metabolism, making it impossible for the organism to survive and breed to create a new generation of bacteria.

Some side effects of gram negative antibiotics can be potentially dangerous.
Some side effects of gram negative antibiotics can be potentially dangerous.

Bacteria associated with urinary, respiratory, and gastrointestinal tract infections are often Gram negative. Doctors treating such infections need to select appropriate Gram negative antibiotics to treat the patient's condition. If the doctor uses the wrong drug, the bacteria will not respond and the infection can get worse. Aminoglycoside antibiotics like streptomycin are examples of Gram negative antibiotics. Bacteria can still develop resistance to them over time as a result of poor habits while taking prescribed antibiotics.

Bacterial cultures may be used to identify the effectiveness of antibiotics for a specific infection.
Bacterial cultures may be used to identify the effectiveness of antibiotics for a specific infection.

Like other antibiotics, these drugs can cause side effects like nausea, headaches, and skin rashes. Patients may have allergic responses in some circumstances, in which case they will develop acute symptoms like difficulty breathing, skin blistering, and hives. If a patient appears to have an allergic response to Gram negative antibiotics, it is advisable to consult a doctor to get rapid treatment, including an alternative antibiotic to treat the patient without sparking another allergic response. If a patient has a history of adverse reactions, this will be noted in the chart to prevent accidental prescriptions for drugs the patient shouldn't take.

Bacteria associated with urinary tract infections are often Gram negative.
Bacteria associated with urinary tract infections are often Gram negative.
Negative antibiotics can cause side effects like headaches.
Negative antibiotics can cause side effects like headaches.
If a patient has an allergic response to Gram negative antibiotics, he or she should consult a doctor.
If a patient has an allergic response to Gram negative antibiotics, he or she should consult a doctor.
The difference between Gram negative and Gram positive bacteria depends on how they perform in certain laboratory tests.
The difference between Gram negative and Gram positive bacteria depends on how they perform in certain laboratory tests.
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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