Phenotypic methods, such as disk diffusion or E-test, directly assess bacterial growth in the presence of macrolides. These provide a rapid, cost-effective initial screen. Minimum inhibitory concentration (MIC) determination using broth microdilution offers greater precision, quantifying the antibiotic concentration required to inhibit bacterial growth. This is particularly useful for guiding treatment choices and surveillance.
Genotypic methods offer a deeper understanding. PCR-based assays targeting specific mutations within the 23S rRNA gene, the primary site of macrolide resistance, are rapid and sensitive. Sequencing this gene provides detailed information on the precise mutations present, informing resistance mechanisms. Whole-genome sequencing allows simultaneous detection of macrolide resistance genes and other resistance determinants, offering a broader antimicrobial resistance profile. This is valuable for complex infections or outbreaks.
Choosing the appropriate method depends on available resources and clinical needs. For rapid screening, phenotypic tests are suitable. For precise MIC determination and detailed resistance mechanism analysis, genotypic methods are preferable. Whole-genome sequencing offers a comprehensive approach, ideal for epidemiological investigations and complex resistance profiles.
