Epidemiological Study on Cigar-shaped Clostridia Isolated in a Local Japanese General Hospital

Cigar-shaped clostridia such as Clostridium clostridioforme and Clostridium symbiosum have been found in serious infections such as bacteremia. In Japan, however, these strains are unrecognized as clinically significant because they are overlooked as unidentified gram-negative rods. We isolated 60 strains of cigar-shaped Clostridium spp. from 48 clinical specimens treated at our laboratory from November 2004 to September 2006. Of these, 19 (39.6%) were primary infections and 29 (60.4%) postsurgical. Primary infections included infected decubitus ulcer (7), peritonitis, intra abdominal abscess, sepsis (2 cases in each group), pyometra, Bartholin's gland abscess, and Fournier's gangrene (1 case in each group). Secondary infections included 28 cases of surgical site infection and 1 case of pyothorax. CRP in 30 cases (62.5%) exeeded 10mg/dL. In 26 (54.2%), WBC exceeded 12, 000/pL. The 60 isolated strains were as follows by 16S rRNA sequencing: Clostridium hathewayi (26.7%), C. clostridioforme (16.7%), Clostridium bolteae (18.3%), Clostridium citroniae (10%), Clostridium aldenense (8.3%), and Clostridium symbiosum (20%). In antimicrobial susceptibility, strains of C. hathewayi showed relatively higher MIC for cefotaxime; (MIC50 64μg/mL, MIC90; 128μg/mL). Three strains of C. bolteae were β-lactamase-producing and their MICs for ampicillin exceeded 128μg/mL.