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

Jiayuan Ye,1,2,* Shanshan Zhao,3,* Yilian Xie,4 Qiuqin Mao,5 Lijun Chen,6 Bing Shen,6 Yuxiang Xu7 1Department of Infectious Diseases, the Shangyu People’s Hospital of Shaoxing University, Shaoxing, Zhejiang Province, People’s Republic of China; 2Health Science Center, Ningbo University, Ningbo, Zhejiang, People’s Republic of China; 3Department of Clinical Laboratory, the Shangyu People’s Hospital of Shaoxing University, Shaoxing, Zhejiang Province, People’s Republic of China; 4Department of Infectious Diseases, the First Affiliated Hospital of Ningbo University, Ningbo, Zhejiang, People’s Republic of China; 5Department of Nursing, the Shangyu People’s Hospital of Shaoxing University, Shaoxing, Zhejiang Province, People’s Republic of China; 6Department of General Medicine, the Shangyu People’s Hospital of Shaoxing University, Shaoxing, Zhejiang Province, People’s Republic of China; 7Medical department, the Shangyu People’s Hospital of Shaoxing University, Shaoxing, Zhejiang Province, People’s Republic of China*These authors contributed equally to this workCorrespondence: Yuxiang Xu, Medical department, the Shangyu People’s Hospital of Shaoxing University, No. 517, Minsheng Avenue, Baiguan Street, Shangyu District, Shaoxing City Shangyu District Baiguan Street City Avenue 517, Shaoxing, Zhejiang Province, People’s Republic of China, Tel +86057582185313, Email [email protected]: 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.Keywords: pilonidal abscess, actinomyces turicensis, actinotignum schaalii, case report, coinfection