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Introduction: Clostridium perfringens and other gas gangrene-forming clostridia are commensals of the human gut and vaginal microbiota, but can cause serious or even fatal infections. As there are relatively few published studies on antibiotic susceptibility of these bacteria, we decided to perform a 10-year retrospective study in a SouthEastern Hungarian clinical centre. Methods: A total of 372 gas gangrene-forming Clostridium spp. were isolated from clinically relevant samples and identified with rapid ID 32A (bioM erieux, France) and MALDI-TOF MS (Bruker Daltinics, Germany) methods. Antibiotic susceptibility was determined with E-tests. Results: We identified 313 C. perfringens, 20 C. septicum, 10 C. sordellii, 10 C. sporogenes, 9 C. tertium, 6 C. bifermentans, 4 C. histolyticum isolates. In C. perfringens isolates, the rate of penicillin resistance was 2.6% and the rate of clindamycin resistance 3.8%. Penicillin resistance was found in 6.8% and clindamycin resistance in 8.5% of the non-perfringens Clostridium spp. isolates. Conclusion: The antibiotic susceptibility of C. perfringens isolates was in good agreement with previous publications. The rates of resistance to penicillin and clindamycin were very low. The resistance rates of non-perfringens Clostridium spp. isolates were higher than those of C. perfringens strains, but lower than those published in the literature.

Solobacterium moorei is a strict anaerobic gram-positive rod. It is found in the human microbiota in different parts of the body, but it also appears to be an opportunistic pathogen in some infectious processes. We describe six cases of severe infections identified in 2016 in which S. moorei was isolated alone or in mixed culture involving other anaerobes or both aerobic and anaerobic bacteria. Three cases were associated with the oral cavity, including a middle ear infection, a wound infection after total laryngectomy, and a mandibular abscess as a result of bisphosphonate therapy. In the other three patients, the sites of infection had no connections with the oral cavity and included chronic osteomyelitis of the tibia, a superinfection of cutaneous tuberculosis associated with hidradenitis suppurativa, and the isolation of S. moorei from the blood culture of a cachectic man with several comorbidities. Based on our findings, S. moorei does not appear to be that virulent of a bacterium; except for the case with bacteraemia, S. moorei was recovered as a co-pathogen in patients with several immunosuppressive predisposing factors. We highlight the finding that the routine use of MALDI-TOF MS in microbiology laboratories can in a timely and detailed manner identify members of mixed infections involving different anaerobic bacteria that may be rare and difficult-to-culture and identify species, such as S. moorei.

In the past 12 years, only a few cases of MDR Bacteroides infections have been reported. Within a comprehensive multicentre survey, we demonstrated the relatively high prevalence of MDR strains isolated in one centre with five isolates as well as one isolate from another centre during a relatively short period of time. This study highlights the importance of antimicrobial susceptibility testing and surveillance among B. fragilis group isolates.

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