title: Optimal Length of Cultivation Time for Isolation of Propionibacterium acnes in Suspected Bone and Joint Infections Is More than 7 Days.
abstract: Diagnosis of Propionibacterium acnes bone and joint infection is challenging due to the long cultivation time of up to 14 days. We retrospectively studied whether reducing the cultivation time to 7 days allows accurate diagnosis without losing sensitivity. We identified patients with at least one positive P. acnes sample between 2005 and 2015 and grouped them into "infection" and "no infection." An infection was defined when at least two samples from the same case were positive. Clinical and microbiological data, including time to positivity for different cultivation methods, were recorded. We found 70 cases of proven P. acnes infection with a significant faster median time to positivity of 6 days (range, 2 to 11 days) compared to 9 days in 47 cases with P. acnes identified as a contamination (P < 0.0001). In 15 of 70 (21.4%) patients with an infection, tissue samples were positive after day 7 and in 6 patients (8.6%) after day 10 when a blind subculture of the thioglycolate broth was performed. The highest sensitivity was detected for thioglycolate broth (66.3%) and the best positive predictive values for anaerobic agar plates (96.5%). A prolonged transportation time from the operating theater to the microbiological laboratory did not influence time to positivity of P. acnes growth. By reducing the cultivation time to 7 days, false-negative diagnoses would increase by 21.4%; thus, we recommend that biopsy specimens from bone and joint infections be cultivated to detect P. acnes for 10 days with a blind subculture at the end.
authors.affiliation: Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Bossard
authors.affiliation: Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
authors.forename: Bruno
authors.initials: B
authors.lastname: Ledergerber
authors.affiliation: Department of Orthopedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland.
authors.forename: Patrick O
authors.initials: PO
authors.lastname: Zingg
authors.affiliation: Department of Orthopedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland.
authors.forename: Christian
authors.initials: C
authors.lastname: Gerber
authors.affiliation: Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
authors.forename: Annelies S
authors.initials: AS
authors.lastname: Zinkernagel
authors.affiliation: Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Zbinden
authors.affiliation: Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland yvonne.achermann@usz.ch.|Department of Orthopedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Achermann
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001170:Arthritis, Infectious / Q000175:diagnosis* / Q000382:microbiology; D003470:Culture Media / Q000378:metabolism; D046508:Culture Techniques / Q000379:methods; D005260:Female; D016908:Gram-Positive Bacterial Infections / Q000175:diagnosis* / Q000382:microbiology; D006621:Hip Joint / Q000382:microbiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011425:Propionibacterium acnes / Q000254:growth & development* / Q000302:isolation & purification*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012785:Shoulder Joint / Q000382:microbiology; D013864:Thioglycolates / Q000378:metabolism; D055815:Young Adult
chemical_list: D003470:Culture Media; D013864:Thioglycolates