Carbapenem
Beta-Lactam Antibiotic

Beta-Lactam Antibiotic

Beta Lactam antibiotics is a group name for all the antibiotics that have Beta-Lactum nucleus in its structure. Most of the frequently used antibiotics are beta lactam. All these antibiotics work on a simple principle of stopping or inhibiting the cell wall synthesis of the bacteria. These are often the most commonly used antibiotics which include penams, which implies penicillin and its derivatives, carbapenems, cephams or monobactams.

Some of these are narrow spectrum, moderate spectrum and broad spectrum antibiotics. Penams themselves are narrow spectrum, which include Beta Lactamase sensitive, Pencillinase resistant pencillins and beta-lactamase resisitant pencillines. Amongst moderate spectrum penicillin’s are amoxicillin and ampicillin, and broad spectrum are amoxicillin+ clavulanic acid. Amongst extended spectrum are azlocillin, piperacillin. Cephalosporins also called Cephems which also belong to this group which are moderate spectrum, moderate spectrum with anti haemophilus activity, with anti anaerobic activity and third generation broad spectrum cephems with anti pseudomonas activity. Fourth generation cephems are broad spectrum which are against gram positive bacteria. Carbanepems also belong to this group, although they are kept as last line of treatment. Amongst those broad spectrum ones are imipenem and meropenem. There are also Monobactams which are less sensitive to cross sensitive reactions. Also Beta Lactamase inhibitors are added to some to prevention of inactivation of beta-lactam antibiotics.

These bacteria sometimes are resistant to beta lactam antibiotics as they produce beta lactamase. This enzyme can be detrimental to the beta lactam ring. Hence, sometimes beta lactamase inhibitors are also given alongwith the antibiotics.

Beta Lactam antibiotics are used against gram positive and gram negative bacteria. These are considered bactericidal. All of these Beta lactam antibiotics have a common structural feature, called a beta-lactam ring The exact mechanism of the action that these antibiotics have is to attack the cell membrane, this happens by deactivating enzymes located in the bacterial cell. In the bacterial cell wall there are certain enzymes, all what these antibiotics do are inactivate these enzymes, which are involved in third stage of cell wall synthesis. So, in effect by taking this antibiotic, you are preventing the last stage of cell wall synthesis of the bacteria that causes infection. In the presence of these beta-lactam antibiotics, the cell wall can no longer protect the new cells and the cells become large spheroblasts. So the cell division does not happen effectively which results in bacteria not surviving and slowly in the infection goes away.

Bacterial resistance to these antibiotics is a great concern. Many of the bacterial species can mutate and resist beta-lactams. Earlier this was limited to some species such as S.marcescens and C.freundi, but later this resistant is found in K.neumoniae etc.

There are some members of this family which are resistant to penicillins but they are not resistant to Extended Spectrum Cephalosporins. However, recently there have been strains that are reported to be resistant to Carbapenems. While Carbapenems are used for very serious infections, but the concern to this resistance is posing serious healthcare challenges.

It is important to mention that many or most of these Beta Lactam antibiotics may cause adverse drug reactions. These can range from nausea, diarrhoea, urticaria, vomiting, erythema, dermatitis. With Carbapenems, these drug reactions can be far more severe. Not very common, but seizures are also a side effect of some of these beta lactams. Sometimes the injection site can become painful. However, it is for the healthcare provider or the patient to see whether the side effects outweigh the benefits provided by these antibiotics to treat infection.

It is always important to report any known allergy to any of these antibiotics. While some of these can be administered orally, some are injected or administered intravenously. It is important to inform your health care provider if you are taking any prescription on non prescription drug while taking any of these antibiotics.