Antimicrobial susceptibility of anaerobic clinical isolates: A two-year surveillance

Robinsoniella peoriensis Infections in Humans-A Narrative Review

Robinsoniella peoriensis is a Gram-positive, strictly anaerobic, spore-forming, rod-shaped bacterium belonging to the phylum Firmicutes and the family Lachnospiraceae. Until now, R. peoriensis is the only species of its genus. It was first isolated in 2003 during a study into the flora of lagoons and manure pits. Given the rarity of this microorganism and the sparse information in the literature about its way of transmission, the way to diagnose its infections and identify it in the microbiology laboratory, and its public health relevance, the present study aimed to identify all the published cases of Robinsoniella, describe the epidemiological, clinical, and microbiological characteristics, and provide information about its antimicrobial resistance, treatment, and outcomes. A narrative review was performed based on a Pubmed/Medline and Scopus databases search. In total, 14 studies provided data on 17 patients with infections by Robinsoniella. The median age of patients was 63 years and 47% were male. The most common types of infection were bone and joint infections, bacteremia, infective endocarditis, and peritonitis. The only isolated species was R. peoriensis, and antimicrobial resistance to clindamycin was 50%, but was 0% to the combination of piperacillin with tazobactam, aminopenicillin with a beta-lactamase inhibitor, and metronidazole which were the most commonly used antimicrobials for the treatment of these infections. The overall mortality depends on the type of infection and is notable only for bacteremia, while all other infections had an optimal outcome. Future studies should better assess these infections' clinical and epidemiological characteristics and the mechanisms of the antimicrobial resistance of this microorganism from a mechanistic and genetic perspective.

Recent Trends in Antimicrobial Resistance among Anaerobic Clinical Isolates

Anaerobic bacteria are normal inhabitants of the human commensal microbiota and play an important role in various human infections. Tedious and time-consuming, antibiotic susceptibility testing is not routinely performed in all clinical microbiology laboratories, despite the increase in antibiotic resistance among clinically relevant anaerobes since the 1990s. β-lactam and metronidazole are the key molecules in the management of anaerobic infections, to the detriment of clindamycin. β-lactam resistance is usually mediated by the production of β-lactamases. Metronidazole resistance remains uncommon, complex, and not fully elucidated, while metronidazole inactivation appears to be a key mechanism. The use of clindamycin, a broad-spectrum anti-anaerobic agent, is becoming problematic due to the increase in resistance rate in all anaerobic bacteria, mainly mediated by Erm-type rRNA methylases. Second-line anti-anaerobes are fluoroquinolones, tetracyclines, chloramphenicol, and linezolid. This review aims to describe the up-to-date evolution of antibiotic resistance, give an overview, and understand the main mechanisms of resistance in a wide range of anaerobes.