Antimicrobial Treatment Options for Granulomatous Mastitis Caused by Corynebacterium Species

Abstract

Corynebacteriumspecies are increasingly recognized as important pathogens in granulomatous mastitis. Currently, there are no published treatment protocols forCorynebacteriumbreast infections. This study describes antimicrobial treatment options in the context of other management strategies used for granulomatous mastitis.Corynebacteriumspp. isolated from breast tissue and aspirate samples stored from 2002 to 2013 were identified and determined to the species level using matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS), 16S RNA sequencing, andrpoBgene targets. The MICs for 12 antimicrobials were performed using Etest for each isolate. Correlations of these with antimicrobial characteristics, choice of antimicrobial, and disease outcome were evaluated.Corynebacteriumspp. from breast tissue and aspirate samples were confirmed in 17 isolates from 16 patients. Based on EUCAST breakpoints,Corynebacterium kroppenstedtiiisolates (n= 11) were susceptible to seven antibiotic classes but resistant to β-lactam antibiotics.Corynebacterium tuberculostearicumisolates (n= 4) were multidrug resistant. Two nonlipophilic species were isolated,Corynebacterium glucuronolyticumandCorynebacterium freneyi, both of which have various susceptibilities to antimicrobial agents. Short-course antimicrobial therapy was common (median, 6 courses per subject; range, 1 to 9 courses). Patients withC. kroppenstedtiipresented with a hot painful breast mass and underwent multiple surgical procedures (median, 4 procedures; range, 2 to 6 procedures). The management ofCorynebacteriumbreast infections requires a multidisciplinary approach and includes culture and appropriate sensitivity testing to guide antimicrobial therapy. Established infections have a poor outcome, possibly because adequate concentrations of some drugs will be difficult to achieve in lipophilic granulomata. Lipophilic antimicrobial therapy may offer a therapeutic advantage. The role of immunotherapy has not been defined.