Examples of resistance genes encoding for the enzymatic modification of antibacterials.

Resistance mechanism	Resistance gene(s)	Enzyme	Resistance phenotype	Ref.
Hydrolytic modification	bla	β-Lactamases	β-Lactam antibiotics in Gram positive and Gram negative	9
	ere	Esterases	Macrolides in Gram positive and Gram negative	26
Chemical modification	aac	Acetyltransferases	Aminoglycosides in Gram positive and Gram negative	27
	ant	Nucleotidyltransferases
	aph	Phosphotransferases
	fosA	Glutathionetransferase	Fosfomycin in Gram positive and Gram negative	28
	fosB	Bacillithioltransferase
	fomA	Phosphotransferases
	fomB
	cat	Acetyltransferases	Chloramphenicol in Gram positive and Gram negative	29
	orf2	Phosphotransferase
	nat	Acetyltransferase	Isoniazid in M. tuberculosis	23
	rgt	Glycosylation	Rifamycin Gram positive and mycobacteria	30
	rph	Phosphotransferase
	arr	Ribosyltransferase
	tetX	Oxidoreductases	Tetracyclines in Gram negative	31