Antibacterial drugs bactericidal effect

The effect of antibacterial drugs can be observed in vitro (3). Bacteria multiply in a growth medium under control conditions. If the medium contains an antibacterial drug, two results can be discerned 1. bacteria are killed—bactericidal effect 2. bacteria survive, but do not multiply-bacteriostatic effect Although variations may occur under therapeutic conditions, different drugs Lullmann, Color Atlas of Pharmacology... 

Consequently, drugs that cause inadequate production of peptidoglycans or other structural components within the cell wall may produce a selective bactericidal effect. Also, a limited number of antibacterial agents directly punch holes in the bacterial cell membrane, destroying the selective permeability and separation of internal from external environment,... 

Antibacterial drugs can be either bactericidal or bacteriostatic The effectiveness of bacteriostatic drugs depends on an intact host immune system. Antimicrobial agents may be administered singly or in combination. Some combinations induce synergy and/or delay emergence of resistance. 

Due to their excellent bactericidal and bacteriostatic properties and their general lack of serious side-effects (ref. 16) the B-lactam antibiotics still belong to the most favoured antibacterial drugs that are avaible. The research activities in the field of 6-lactam antibiotics including the chemical synthesis of 6-lactam antibiotics and related compounds, have increased up to now (ref. 16). 

In many therapeutic situations the drug combinations are completely misused (12). Adding another drug to a combination does not reduce the need for sound clinical judgement in therapy. Although there are many disease situations in which the use of more than one antibacterial agent may be justified, generalizations about various combinations of bactericidal or bacteriostatic antibiotics or admixtures have not proven valid. Basically, antibiotic combinations should be avoided as a common practice unless they have shown a clear increase in effectiveness as reported in the literature. 

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