A Rare Case of Sacrococcygeal Pilonidal Abscess Caused by Coinfection of Actinomyces Turicensis and Actinotignum Schaalii: A Case Report.

Sacrococcygeal pilonidal abscesses are typically caused by anaerobic and Gram-negative bacteria due to their anatomical proximity to the anus; however, mixed infections involving Actinomyces and Actinotignum species are exceptionally rare, and to our knowledge, this is the first reported case of a sacrococcygeal pilonidal abscesses caused by Actinomyces turicensis and Actinotignum schaalii. The patient, an 18-year-old female, presented with one week of localized pain, redness, and swelling, which failed to respond to conventional antibiotics. Pelvic CT revealed an abscess, prompting surgical debridement and subsequent recovery. Rapid pathogen identification was achieved using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) from a single colony culture. This case underscores the importance of microbiological identification using tools like MALDI-TOF MS to recognize uncommon pathogens, which is critical for avoiding ineffective empiric antibiotics and guiding appropriate therapy. Further research is needed to optimize management strategies for such rare infections.