ermB / ermC — MLSb resistance

Mechanism

Methylate the 23S ribosomal RNA target shared by macrolides, lincosamides and streptogramin B.

What it removes from the grid

Erythromycin, azithromycin, clarithromycin and clindamycin.

What it spares

Agents that act elsewhere — the oxazolidinones, glycopeptides and beta-lactams are unaffected.

A multiplex panel can't say which organism in a mixed specimen carries a detected gene. CORE-ABR applies ermB / ermC only to organisms known to carry it, and only to the agents its mechanism defeats — so a detected gene moves the right cells and spares the rest.

Organisms it is applied to

Staphylococcus aureusThe leading cause of skin and soft-tissue infection, and the organism most wound reports are built around.Gram-positive bacteria · UTI · Wound · STI Staphylococcus epidermidisA coagulase-negative staphylococcus that lives on normal skin. Usually a colonizer; sometimes the cause — particularly w…Gram-positive bacteria · UTI · Wound Streptococcus pyogenesGroup A streptococcus — a cause of cellulitis, erysipelas and necrotizing soft-tissue infection.Gram-positive bacteria · UTI · Wound Streptococcus agalactiaeGroup B streptococcus — found in urinary, genital and diabetic-foot specimens.Gram-positive bacteria · UTI · Wound Streptococcus pneumoniaePneumococcus — primarily a respiratory pathogen, included on some wound panels.Gram-positive bacteria · Wound Enterococcus speciesGram-positive cocci common in urinary and wound specimens. Many panels detect E. faecalis and E. faecium in one pooled w…Gram-positive bacteria · UTI · Wound Cutibacterium acnesAn anaerobic gram-positive rod of normal skin. Most often a colonizer or contaminant; a genuine cause of device, shoulde…Gram-positive bacteria · Wound

Coding

Z16.29 (resistance to other single specified antibiotic), as documentation supports. CORE-ABR adds resistance findings as supporting codes, not primary, and prints the rationale on the report.

Tagged

Decision support only. The treating clinician decides. Molecular genotype does not replace phenotypic susceptibility testing, culture, or public-health reporting. Absence of a detected resistance gene does not establish susceptibility. Organism targets vary by panel; CORE-ABR is configured to the assay each laboratory runs.