Understanding antibiotic resistance
Understanding antibiotic resistance

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Understanding antibiotic resistance

2.1 Classification

There are numerous different antibiotics, some of which are naturally occurring while others are semi- or fully synthetic. Don’t worry if you don’t understand these terms, as they will be explained later. One of the most useful ways of classifying antibiotics is by chemical structure because structurally similar antibiotics tend to have similar antibacterial activity.

Examples of common antibiotic classes are shown in Table 1.

Table 1 Common classes of antibiotic

Antibiotic class Example Cellular process targeted* Effect on bacteria**
ß-Lactams (penicillins) ampicillin bacterial cell wall synthesis bactericidal
ß-Lactams (cephalosporins) cephazolin bacterial cell wall synthesis bactericidal
ß-Lactams (carbapenems) imipenem bacterial cell wall synthesis bactericidal
Glycopeptides vancomycin bacterial cell wall synthesis bactericidal
Aminoglycosides streptomycin protein synthesis bactericidal
Macrolides azithromycin protein synthesis bacteriostatic
Tetracyclines tetracycline protein synthesis bacteriostatic
Oxazolidinones linezolid protein synthesis bacteriostatic
Fluoroquinolones ciprofloxacin DNA synthesis bactericidal
Rifamycins rifampicin RNA synthesis bactericidal
Not applicable trimethoprim metabolic reactions bactericidal
(Source: OpenStax College Microbiology, n.d.)
* You will learn more about these cellular processes in Week 2.
** Common effect but partly depends on the concentration at which the antibiotic is used.

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