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Culture of periprosthetic tissue specimens in blood culture bottles is more sensitive than conventional techniques, but the impact on laboratory workflow has yet to be addressed. Herein, we examined the impact of culture of periprosthetic tissues in blood culture bottles on laboratory workflow and cost. The workflow was process mapped, decision tree models were constructed using probabilities of positive and negative cultures drawn from our published study (T. N. Peel, B. L. Dylla, J. G. Hughes, D. T. Lynch, K. E. Greenwood-Quaintance, A. C. Cheng, J. N. Mandrekar, and R. Patel, mBio 7:e01776-15, 2016, https://doi.org/10.1128/mBio.01776-15), and the processing times and resource costs from the laboratory staff time viewpoint were used to compare periprosthetic tissues culture processes using conventional techniques with culture in blood culture bottles. Sensitivity analysis was performed using various rates of positive cultures. Annualized labor savings were estimated based on salary costs from the U.S. Labor Bureau for Laboratory staff. The model demonstrated a 60.1% reduction in mean total staff time with the adoption of tissue inoculation into blood culture bottles compared to conventional techniques (mean ± standard deviation, 30.7 ± 27.6 versus 77.0 ± 35.3 h per month, respectively; < 0.001). The estimated annualized labor cost savings of culture using blood culture bottles was $10,876.83 (±$337.16). Sensitivity analysis was performed using various rates of culture positivity (5 to 50%). Culture in blood culture bottles was cost-effective, based on the estimated labor cost savings of $2,132.71 for each percent increase in test accuracy. In conclusion, culture of periprosthetic tissue in blood culture bottles is not only more accurate than but is also cost-saving compared to conventional culture methods.

Background Current approaches in tracking Clostridioides difficile infection (CDI) and individualizing patient management are incompletely defined. Methods We recruited 468 subjects with C. difficile infection at Mayo Clinic Rochester between May and December 2016 and performed whole genome sequencing (WGS) on C. difficile isolates from 397. WGS was also performed on isolates from a subset of the subjects at the time of recurrence of infection. Sequence data were analyzed by determining core genome multilocus sequence type (cgMLST), with isolates grouped by allelic differences and predicted ribotype. Results There was no correlation between C. difficile isolates based on cgMLST or ribotype groupings and CDI outcome. Epidemiologic assessment of hospitalized subjects harboring C. difficile isolates with ≤2 allelic differences based on standard infection prevention and control assessment revealed no evidence of person-to-person transmission. Interestingly, community-acquired CDI subjects in 40% of groups with ≤2 allelic differences resided within the same zip code. Among 18 subjects clinically classified as having recurrent CDI, WGS revealed 14 with initial and subsequent isolates differing by ≤2 allelic differences, suggesting relapse of infection with the same initial strain, and 4 with isolates differing by &gt;50 allelic differences, suggesting reinfection. Among the 5 subjects classified as having reinfection based on timing of recurrence, 3 had isolates with ≤2 allelic differences between them suggesting relapse, with 2 having isolates differing by &gt;50 allelic differences - suggesting reinfection. Conclusions Our findings point to potential transmission of C. difficile in the community. WGS better differentiates relapse from reinfection than do definitions based on timing of recurrence.

Propionibacterium acnes is an agent of shoulder infection, especially postsurgically (1, 2). The study by Butler-Wu et al. suggests a minimum culture incubation of 13 days for recovery of P. acnes from periprosthetic tissues and fluids (3). Methods for recovery of anaerobes vary, and parameters beyond duration of incubation may influence optimal P. acnes recovery. Butler-Wu et al. did not use anaerobic broth culture, and specimens were not transported under anaerobic conditions. We have routinely collected specimens for anaerobic culture into anaerobic tissue/fluid vials and have included an anaerobic thioglycolate broth incubated for 7 days in our anaerobic bacterial isolation strategy for tissue specimens. We had not been aware of any obvious limitation in isolation of P. acnes using this approach. In response to the findings by Butler-Wu et al., we examined whether 2-week culture incubation is needed for isolation of P. acnes when utilizing an anaerobic thioglycolate broth in conjunction with collection of specimens into anaerobic tissue/fluid vials.Our study was performed over ϳ6 months in 2011. Immediately following collection in the operating room, orthopedic fluids and tissues were placed into anaerobic fluid vials (20-ml serum stopper vials with 1.3 ml prereduced peptone yeast extract broth, 0.5 g/liter cysteine hydrochloride, and 1 mg/liter resazurin indicator) or tissue vials (sterile 30-ml screw-top vials filled with CO 2 ), respectively. Tissues were homogenized using a Seward Stomacher 80 Biomaster (Seward Inc., Port St. Lucie, FL) in 3 ml of brain heart infusion broth for 1 min. A 0.1-ml sample of tissue homogenate or fluid in anaerobic transport medium was inoculated onto CDC anaerobic sheep blood agar and placed in a CO 2 -flushed holding jar which, within 2 h, was set up with an AnaeroPack (Thermo Fisher Scientific, Lenexa, KS). After the jar was opened for plate examination, subsequent incubation was in a glove box at 37°C for 14 days. A 1-ml sample of fluid or homogenate was also inoculated into an anaerobically prereduced hemin-thioglycolate broth, which was closed and incubated at 37°C for 14 days. The broth was examined daily or until positive; cloudy broth was subcultured. The plate was examined Monday, Wednesday, and Friday for the first week and then on days 7 and 14 or until positive. Subjects with more than one specimen cultured on the same date (event) from a shoulder bone/joint source and with more than one specimen yielding P. acnes (1, 4) were analyzed.Fourteen subjects had more than one positive shoulder bone/joint culture for P. acnes. (One subject had two events, and another subject, who had blastomycosis of the joint from which P. acnes was isolated, was excluded, yielding 14 analyzed events.) The Butler-Wu study was similar in size, with 17 patient events involving more than one specimen culture positive for P. acnes (3). Among the 14 events in our study, there were 72 anaerobic plate and broth cultures performed (range, 3 to 13 per event); P. acnes grew on 28 plates (27 withi...

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