<prompt> Not a mechanism of resistance to erythromycin?Alteration in ribosomal binding sitePlasmid mediatedErythromycin esterase productionEfflux proteins  <response>: Ans. is None c i.e., Erythromycin esterase production o All are true. Mechanism of drug resistance for erythromycin o Bacterial resistance to erythromycin occurs by: i Target site alteration alteration in the 505 ribosomal binding site by methylation by enzyme methylase which is encoded by plasmid -4 Most common ii Altered transpo with active efflux to pump it out by efflusx protein -- 2nd most common iii Drug modification by enzyme, i.e. erythromycin esterase rare o Mechanisms i and ii are the most common mechanisms for bacterial resistance to erythromycin o Resistance may be chromosomal mediated or plasmid mediated and it may be inducible or constitutive. o Resistance to erythromycin implies resistance to all macrolides. Coming back to question o Most appropriate answer of this question is None. o However, if the question is repeated as such go ahead with option c because: 1. Two most common mechanism for erythromycin resistance are: i Alteration in ribosomoal binding side option a by plasmid encoded option b methylase ii Active efflux of drug by efflux protein option d 2. Production of erythromycin esterase is an uncommon mechanism for erythromycin resistance. 