Special Phenotypic Methods for Detecting Antibacterial Resistance

Abstract

Special phenotypic tests may be performed as an adjunct or surrogate to standard antimicrobial susceptibility testing methods to help characterize an isolate's antimicrobial susceptibility to a drug or drug class or detect a particular resistance mechanism or phenotype. Special phenotypic susceptibility tests are categorized into supplemental tests, screening tests, surrogate agent tests, and equivalent agent tests. Phenotypic methods for the detection of resistance have been developed for use with both clinical specimens and cultured growth. Resistance to streptomycin is mediated by a different resistance mechanism, and consequently, streptomycin resistance must be determined separately from gentamicin resistance. Although erythromycin and clindamycin are in separate antimicrobial agent classes, i.e., macrolides and lincosamides, respectively, their mechanisms of action and mechanisms of resistance are similar. Antimicrobial resistance among Gram‐negative bacilli, and especially resistance to β‐lactam agents, is a serious public health concern worldwide.