A combination antibiotic is one in which two ingredients are added together for additional therapeutic effect. One or both ingredients may be antibiotics. Antibiotic combinations are increasingly important because of

antimicrobial resistance Antimicrobial resistance (AMR) occurs when microbes evolve mechanisms that protect them from the effects of antimicrobials. All classes of microbes can evolve resistance. Fungi evolve antifungal resistance. Viruses evolve antiviral resistance. ...

. This means that individual antibiotics that used to be effective are no longer effective, and because of the absence of new classes of antibiotic, they allow old antibiotics to be continue to be used. In particular, they may be required to treat

multiresistant organisms Multiple drug resistance (MDR), multidrug resistance or multiresistance is antimicrobial resistance shown by a species of microorganism to at least one antimicrobial drug in three or more antimicrobial categories. Antimicrobial categories are c ...

, such as

carbapenem-resistant Enterobacteriaceae Carbapenem-resistant Enterobacteriaceae (CRE) or carbapenemase-producing Enterobacteriaceae (CPE) are Gram-negative bacteria that are resistant to the carbapenem class of antibiotics, considered the drugs of last resort for such infections. They ...

. Some combinations are more likely to result in successful treatment of an infection.

Uses

Antibiotics are used in combination for a number of reasons: * to treat

, such as

. *

Amoxicillin/clavulanic acid Amoxicillin/clavulanic acid, also known as co-amoxiclav or amox-clav, sold under the brand name Augmentin, among others, is an antibiotic medication used for the treatment of a number of bacterial infections. It is a combination consisting of a ...

, which includes the

beta lactam A beta-lactam (β-lactam) ring is a four-membered lactam. A ''lactam'' is a cyclic amide, and ''beta''-lactams are named so because the nitrogen atom is attached to the β-carbon atom relative to the carbonyl. The simplest β-lactam possible is ...

amoxicillin with the suicide inhibitor clauvanic acid, which helps the amoxicillin overcome the action of

beta lactamase Beta-lactamases, (β-lactamases) are enzymes () produced by bacteria that provide multi-resistance to beta-lactam antibiotics such as penicillins, cephalosporins, cephamycins, monobactams and carbapenems (ertapenem), although carbapenem ...

* because a person may be infected with more than one microbe simultaneously, for example infections of the

abdominal cavity The abdominal cavity is a large body cavity in humans and many other animals that contains many organs. It is a part of the abdominopelvic cavity. It is located below the thoracic cavity, and above the pelvic cavity. Its dome-shaped roof is the th ...

after

bowel perforation Gastrointestinal perforation, also known as ruptured bowel, is a hole in the wall of part of the gastrointestinal tract. The gastrointestinal tract includes the esophagus, stomach, small intestine, and large intestine. Symptoms include severe abd ...

. * because antibiotics used together may act synergisticly to increase the efficacy of both, * because antibiotics used together may have a broader spectrum than each antibiotic used individually.

Examples

Examples of combinations include: *

, which includes the

amoxicillin with the suicide inhibitor clauvanic acid, which helps the amoxicillin overcome the action of

Trimethoprim/sulfamethoxazole Trimethoprim/sulfamethoxazole, sold under the brand name Bactrim among others, is a fixed-dose combination antibiotic medication used to treat a variety of bacterial infections. It consists of one part trimethoprim to five parts sulfamethoxazo ...

Research

Research into combination antibiotics is ongoing.

References

{{reflist Antibiotics *