Pharmacology for Anaesthesia and Intensive Care

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Antimicrobials

Antimicrobial agents are used to kill or suppress the growth of microorganisms.

The term antibiotic specifically refers to a chemical substance that is produced by

microorganisms and has the capacity to kill or inhibit the growth of another microor-

ganism.

Antimicrobials are used widely in intensive care where the selection and dissem-

ination of resistance is a constant concern. Methicillin ResistantStaphylococcus

Aureus(MRSA) and Vancomycin Resistant Enterococcus (VRE) have caused out-

breaks in developed countries costing millions to control. Antimicrobial therapy

should be directed by microbiological evidence wherever possible, empirical treat-

ment should be rationalised to appropriate narrow spectrum cover and treatment

should be discontinued at the earliest opportunity. The choice of agent must be

influenced by unit protocols that will reflect the local pathogen prevalence and their

known pattern of sensitivity.

This chapter can, therefore, only generalize about each agent’s spectrum of activ-

ity and will refrain from suggesting appropriate treatment regimes. The following

headings are used to discuss the various antimicrobials:


Antibacterial drugs


Antifungal drugs


Antiviral drugs

Antibacterial drugs

β-Lactam antibacterial drugs

β-Lactam drugs can be subdivided into


Penicillins


Cephalosporins


Carbapenems


Monobactams

Penicillins

This group of antimicrobial drugs are based around the penicillin nucleus, which

contains a fusedβ-lactam/thiazolidine ring.