Experience with Infections Caused by Tissierella praeacuta: An Emerging Anaerobic Surgical Pathogen.

Background: Tissierella praeacuta (TP), previously known as Clostridium hastiforme, is a rare and potentially underreported pathogen. TP may cause a variety of infections, including the potential as an important pathogen of intra-abdominal infections (IAIs). Still little data on this anaerobic gram-positive rod are available. Patients and Methods: The institutional database was searched for TP infections during a 4-year period. Isolation and identification of the pathogen were done according to standard guidelines, including those for anaerobic culture. Results: A total of 21 patients, including 11 males and 10 females, with a median age of 63.8 (range 35.8-90) years with infections because of TP (24 isolates) were identified. There were eight IAIs, 12 soft tissue infections, and 1 pleural empyema; two patients had bacteremia. In 19 cases, microscopy was done revealing white blood cells in 79%, gram-positive cocci in 53%, gram-negative rods in 47%, and gram-positive rods in 32%. Final cultures grew TP monoculture in 38%; in 62%, TP was part of a mixed flora. Twenty-four co-pathogens were identified, including gram-positive cocci (13), gram-negative rods (9), and gram-positive rods (2). Treatment consisted of antibiotic agents, including beta-lactams, clindamycin, or metronidazole, and surgery or interventional drainage for the majority of cases. Outcomes were generally favorable with 19 of the 21 patients surviving. Conclusions: This is a first large series of infections because of the emerging pathogen TP from a rural area. TP mainly causes purulent infections requiring surgical intervention. The series emphasizes the importance of anaerobic cultures in surgical specimens.