Escherichia coli is a Gram negative bacillus which produces penicillinases, but it remains sensitive to numerous antibiotics.

Bacterial resistance to antibiotics is a major problem and where possible sensitivities should be checked before blind treatment of infections is commenced.

Ampicillin and amoxicillin are broad spectrum antibiotics active against non-beta lactamase producing Gram positive and Gram negative organisms. They are inactivated by penicillinases and since up to 50% ofEscherichia coli strains are now resistant, they would be an unsuitable choice.

Co-amoxiclav consists of amoxicillin and the beta-lactamase inhibitor clavulanic acid. Thus it is active against beta-lactamase producing bacteria that are resistant to amoxicillin, including strains of Escherichia coli.

Cefuroxime is a cephalosporin that is resistant to inactivation by bacterial beta-lactamases and so may be used against Escherichia coli.

Ciprofloxacin has a 6-fluoro substituent which confers enhanced antibacterial potency against both Gram positive and Gram negative organisms, including Escherichia coli.