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Monobactam – Effect, Application & Risks


Monobactams are a group of antibiotics that are often used as a last resort or in combination with other antibiotics. The best- known representative is the antibiotic Aztreonam .

What is Monobactam?

Monobactams are semi-synthetic antibiotics. Gram -negative bacteria produce a substance that is then synthetically modified. Like other ß-lactam antibiotics, monobactam contains a monocyclic ß-lactam ring. ß-Lactam is a cyclic organic chemical compound containing an amide bond in the ring. However, monobactams do not contain an additional fused ring. This is a typical property of ß-lactam antibiotics.

Monobactams are stable to ß-lactamase. ß-lactamases are enzymes produced by various bacteria. They play a crucial role in the development of antibiotic resistance by bacteria. However, antibiotics from the group of monobactams can be cleaved by extended spectrum ß-lactamases (ESBL). Thus, ESBL-producing bacteria such as E.coli and Klebsiella are resistant to monobactams.

Pharmacological action

Monobactams have a bactericidal effect. They inhibit the synthesis of the cell wall of bacteria. The cell wall is vital for bacteria. They have a very high osmotic particle concentration within their cell plasma. If the cell wall is no longer there or is damaged, water flows into the interior of the bacteria’s cell. They swell, so over time the plasmalemma, a cell membrane that encloses the cytoplasm, ruptures. The bacteria burst and perish.

The spectrum of activity of monobactams is quite broad. They work primarily in the gram-negative range. Gram-negative bacteria can be stained red in the Gram stain. In contrast to gram-positive bacteria, in addition to a thin peptidoglycan layer made of murein, they also have another outer cell membrane. Gram- negative pathogens include, for example , staphylococci , streptococci , mycobacteria , nocardia, listeria and clostridia .

Monobactams have no effect on gram-positive pathogens such as legionella , campylobacter , helicobacter pylori , enterobacteria , borrelia and chlamydia . Anaerobes cannot be treated with antibiotics from this group either. Since monobactams cannot be absorbed from the gastrointestinal tract , they must be administered parenterally. This means that they are usually injected into a vein . Intramuscular or inhalative application is also possible.

The bioavailability of monobactams is almost 100 percent. Metabolism takes place in the liver . The kidneys then excrete the resulting metabolites.

Medical Application & Use

Monobactams act mainly as reserve antibiotics. These special antibiotics may only be used in infections with resistant pathogens. In the case of severe infections, they are also used directly if an infestation by resistant pathogens is to be expected. It should be noted that reserve antibiotics are by no means more effective than standard antibiotics. Often they even have a worse effect and are associated with more side effects. However, they are still effective against resistant pathogens.

Monobactams are used in particular in the treatment of complicated urinary tract infections or intra-abdominal infections. For this purpose, the drugs are combined with the antibiotics metronidazole or clindamycin . The effect of the monobactams must also be verified by an antibiogram.

The main indication for the use of aztreonam, the main representative of monobactams, is chronic lung infection with the pathogen Pseudomonas aeruginosa in patients with cystic fibrosis . Cystic fibrosis is an inherited disease characterized by the production of a viscous secretion by the body’s exocrine glands . Antibiotics from the monobactam group are also used in patients with an allergy to penicillin or cephalosporins .

Risks & side effects

Monobactams should not be used in children under the age of 18. Its use is also contraindicated in patients with renal dysfunction or in patients who are allergic to beta-lactam antibiotics.

Adverse drug effects include coughing and wheezing. Pain in the throat or larynx can also occur. Other side effects include nasal congestion and runny to slimy nasal discharge.

Some patients also experience fever and chest discomfort when treated with monobactams . Bronchial spasms can also be one of the possible side effects. A rash may also develop during treatment .

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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.