Elaboration of inactivating enzymes are the impoant mechanism of drug resistance among all of these antibiotics EXCEPT:
QUINOLONES AND FLUROQUIONOLONES- QUINOLONES:NALIDIXIC ACID FLUROQUINOLONES:CIPROFLOXACIN,NORFLOXACIN,PERFLOXACIN,OFLOXACIN,LEVOFLOXACIN Mechanism of resistance :Because of the unique mechanism of action, plasmid mediated transferable resistance probably does not occur. Resistance noted so far is due to chromosomal mutation producing a DNA gyrase or topeisomerase IV with reduced affinity for FQs, or due to reduced permeability / increased efflux of these drugs across bacterial membranes. In contrast to nalidixic acid which selects single step resistant mutants at high frequency, FQ-resistant mutants are not easily selected. Therefore, resistance to FQs has been slow to develop. However, increasing resistance has been repoed among Salmonella, Pseudomonas, staphylococci, gonococci and pneumococci. ESSENTIALS OF MEDICAL PHARMACOLOGY K.D.TRIPATHI SIXTH EDITION PAGE NO:688
Quinolones
Penicillin
Chloramphenicol
Aminoglycosides
Chemotherapy