Monobactams are bacterially-produced monocyclic β-lactam antibiotics. The β-lactam ring is not fused to another ring, in contrast to most other β-lactams. Monobactams are narrow-spectrum antibiotics effective only against (strictly or facultatively) aerobic

Gram-negative Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is that their cell envelope consists ...

bacilli Bacilli is a Taxonomy (biology), taxonomic Class (biology), class of bacteria that includes two orders, Bacillales and Lactobacillales, which contain several well-known pathogens such as ''Bacillus anthracis'' (the cause of anthrax). ''Bacilli'' ...

, exhibiting a high level of resistance to beta-lactamases of these organisms. Due to their narrow spectrum, monobactams can be used to treat infections by susceptible bacteria without disrupting the patient's

microbiota Microbiota are the range of microorganisms that may be commensal, mutualistic, or pathogenic found in and on all multicellular organisms, including plants. Microbiota include bacteria, archaea, protists, fungi, and viruses, and have been found ...

. Monobactams are nevertheless seldom used. Aztreonam is the archetypal monobactam. Other monobactams include tigemonam, nocardicin A, carumonam and tabtoxin. An example of a monobactam that lacks antibiotic activity, but is used clinically for other purposes, is the cholesterol absorption inhibitor ezetimibe which is used to treat

hypercholesterolemia Hypercholesterolemia, also called high cholesterol, is the presence of high levels of cholesterol in the blood. It is a form of hyperlipidemia (high levels of lipids in the blood), hyperlipoproteinemia (high levels of lipoproteins in the blood), ...

Pharmacology

Monobactams exert their antibacterial effects by binding to penicillin-binding proteins (PBPs), thereby inhibiting bacterial wall synthesis. Monobactams exhibit poor affinity for PBPs of Gram-positive bacteria as well as of strictly anaerobic bacteria, resulting in a lack of significant antimicrobial activity against these kinds of organisms. Monobactams are synergetic with

aminoglycosides Aminoglycoside is a medicinal chemistry, medicinal and bacteriology, bacteriologic category of traditional Gram-negative antibacterial medications that inhibit protein synthesis and contain as a portion of the molecule an amino-modified glycoside ...

, and piperacillin. Bacterial resistance to monobactams have been observed, and is mediated by bacterial beta-lactamases.

Adverse effects

Adverse effects to monobactams can include skin rash and occasional abnormal liver functions. Monobactam antibiotics exhibit no IgE cross-reactivity reactions with

penicillin Penicillins (P, PCN or PEN) are a group of beta-lactam antibiotic, β-lactam antibiotics originally obtained from ''Penicillium'' Mold (fungus), moulds, principally ''Penicillium chrysogenum, P. chrysogenum'' and ''Penicillium rubens, P. ru ...

but have shown some cross reactivity with

cephalosporin The cephalosporins (sg. ) are a class of β-lactam antibiotics originally derived from the fungus '' Acremonium'', which was previously known as ''Cephalosporium''. Together with cephamycins, they constitute a subgroup of β-lactam antibio ...

s, most notably ceftazidime, which contains an identical side chain as aztreonam. Monobactams can trigger seizures in patients with history of seizures, although the risk is lower than with penicillins.

Research

Siderophore-conjugated monobactams show promise for the treatment of multi drug-resistant pathogens.

References

External links

* {{CephalosporinAntiBiotics