1361. Actinotignum schaalii an Under-recognized Cause of Infections: A Case Series in Calgary from 2012 - 2020

Abstract

Abstract Background Actinotignum schaalii is a gram-positive rod that is a fastidious commensal of the urogenital tract. Infections with A. schaalii are underdiagnosed previously because phenotypic methods fail to identify it. Both MALDI-TOF mass spectrometry and 16S rRNA sequencing allow definitive identification of this opportunistic emerging pathogen. A. schaalii is an infrequent but important cause of UTIs in the elderly, particularly with urological abnormalities. The spectrum of invasive disease caused by A. schaalii is not well characterized; however, it has been isolated in severe infections including necrotizing skin and soft tissue infections, bacteremia, osteomyelitis, and endocarditis. We used a population-based approach to characterize and describe the clinical and microbiological features of invasive A. schaalii infections in our region. Methods All adult and pediatric cases enrolled had microbiological isolates of Actinotignum schaalii recovered from blood cultures, sterile fluids and tissue cultures from Jan 2012 to Dec 2020 by APL, a regional centralized microbiology laboratory serving the Calgary Zone in Alberta, Canada. Clinical data were retrieved and linked from administrative health databases, chart review and the laboratory information system. Standard descriptive statistics were used. Results We identified 84 unique A. schaalii infections, 35 were from bloodstream, 32 soft tissue, 7 post-operative infections. Median age and Charslon comorbidity score was higher in BSI. 54.3% of patient with BSI had a genitourinary pathology, with 51.4% caused by a complicated urinary infection, while soft and skin tissue infections caused 65.3% of non-BSI. Using EUCAST MIC cut-offs, 48% and 100% of the isolates were resistant to clindamycin and metronidazole, respectively. In contrast, all specimens were susceptible to penicillin. Hospitalization and 90-days mortality were higher in the BSI group. Conclusion A. schaalii is an anaerobic opportunistic pathogen that can cause life-threatening invasive infections, particularly in older adults with underlying genitourinary pathology. BSI were associated with higher rates of hospitalization and mortality. In contrast, patients with A. schaalii isolated from cutaneous sources were younger and had better clinical outcomes. Disclosures All Authors: No reported disclosures