Multidrug resistance in anaerobes

Multidrug resistance (MDR) in anaerobes is not a well-known topic. Bacteroides fragilis group isolates have numerous resistance determinants such as multidrug efflux pumps, cfiA and nimB genes and activating insertion sequences, and some isolates exhibited extensive drug-resistant patterns. MDR rates in B. fragilis group were from 1.5 to >18% and up to >71% in cfiA and nimB positive isolates carrying insertion sequences. MDR was present in >1/2 of Clostridioides difficile isolates, most often in epidemic/hypervirulent strains and unusually high metronidazole or vancomycin resistance has been reported in single studies. MDR was found in Prevotella spp. (in <= 10% of isolates), Finegoldia magna, Veillonella spp. and Cutibac-terium acnes. Resistance in the anaerobes tends to be less predictable and anaerobic microbiology is required in more laboratories. New hopes may be new antibiotics such as eravacycline, cadazolid, suroto-mycin, ridinilazol or C. difficile toxoid vaccines; however, more efforts are needed to track the MDR in anaerobes.