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Antimicrobial Use

Learn more about the different types of antimicrobial therapy.
Pillbox containing pills

Antibiotics are used for a variety of infections. For some infections, a singular antimicrobial agent is used (monotherapy) and for others, multiple antibiotics are employed (combination therapy). The decision as to which treatment approach is used is often dependent on the species of the bacterial infection.

Each methodology has its advantages and disadvantages, though these can change depending on the specific infection that needs to be treated. For now, we will look at the generic pros and cons of each treatment regime.


The table below displays the advantages and disadvantages of using a singular microbial agent to treat an infection.

Advantages Disadvantages
Fewer sides effects – can be less toxic than combination therapy May not be as potent as using multiple antibiotics
Potentially less expensive than combination therapy

Combination Antibiotic Therapy

The table below shows the advantages and disadvantages of using multiple antibiotics to treat an infection.

Advantages Disadvantages
Potentially more effective at treating an infection due to synergistic mechanisms of action Potentially more adverse side effects – more toxic to the patient
Potentially more effective at treating multiple-drug resistant infections May increase antibiotic resistance
Potentially more effective when treating an infection that contains different species of bacteria May increase costs
May prevent antibiotic resistance

As mentioned in previous steps, the mechanism of action can differ in varying antibiotics. The knowledge of different mechanisms of actions and combining antibiotics with different mechanisms of actions can cause a synergistic effect. A synergistic effect of multiple antibiotics used simultaneously, is often described as an enhanced result in treating an infection, which is more effective than if the infection was treated with each antibiotic singularly.

In the treatment of stomach ulcers caused by Helicobacter pylori, usually multiple antibiotics are used, as well as a proton pump inhibitor. As for the antibiotics, one is usually amoxicillin, a penicillin which targets the cell wall. The second antibiotic that is often used is clarithromycin, which belongs to the drug class of macrolides which target the ribosomes. This synergistic combination of these antibiotics is more effective than trying to treat the stomach ulcer with just one of these antibiotics.

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Introduction to Practical Microbiology

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