3rd August 2023

Others

Other important antibiotics to be aware of are summarised in the table below.

Antibiotic	Mechanism	Spectrum	Notes
Clindamycin	Similar to macrolides – bacteriostatic drugs, which inhibit bacterial growth by binding to the 50s subunit of the bacterial ribosome	Gram positive and anaerobic cover	Often used in skin and soft tissue infections
Trimethoprim	Bactericidal – inhibits dihydrofolate reductase.	Gram positive and gram negative – but best known for the cover of Gram negative anaerobes	Commonly used to treat UTIs Contraindicated in pregnancy due to its effect on folate levels, and with the antifolate drug methotrexate
Co-trimoxazole (sulfamethoxazole/Trimethoprim	Sulfamethoxazole also acts on the folate metabolism pathway	Broad spectrum against Gram positive and negative bacteria	The addition of Sulfamethoxazole to Trimethoprim results in a synergistic effect Used to treat Pneumocystis jirovecii pneumonia
Nitrofurantoin	Poorly understood – damages bacterial DNA	Concentrated in the urine, so highly useful against a variety of Gram positive and negative pathogens that cause UTI	Often first line for UTI Contraindicated in people with renal impairment
Metronidazole	Nitroimidazole antibiotic, which inhibits nucleic acid synthesis	Effective against anaerobic bacteria and parasitic infections	Alcohol consumption is advised against whilst taking metronidazole. Used to treat pelvic inflammatory disease, to provide Gram negative and anaerobic cover in intra-abdominal infections, and to treat bacterial vaginosis and Giardiasis

Table 2: Miscellaneous antibacterial drugs

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