Title: Culturing periprosthetic tissue in blood culture bottles results in isolation of additional microorganisms.  van den Bijllaardt W, van der Jagt OP, Peijs M, Janssens M, Buiting AG, Reuwer AQ. European Journal of Clinical Microbiology & Infectious Diseases. 2018 Epub. DOI: 10.1007/s10096-018-3420-6

Summary and Editorial by  Dr. Marjan Wouthuyzen-Bakker and Dr. Sreeram Penna

The aim of this prospective clinical validation study was to evaluate if there is an added diagnostic value to culturing periprosthetic tissues in blood culture bottles (BCB) in addition to standard conventional cultures in diagnosing periprosthetic joint infection (PJI). The study was conducted over a 12-month period with 113 episodes in 90 patients. The researchers utilized the Infectious Diseases Society of America (IDSA) criteria for PJI as a gold standard in assessing sensitivity and specificity of culture. In the studied cohort, 45 patients met the IDSA criteria for PJI, and of these cases, 34 were acute infections. The main finding of this study was that periprosthetic tissue cultures in BCB led to the isolation of additional microorganisms in 30% of cases and increased the sensitivity for PJI diagnosis with 10% compared to standard cultures in agar and broth. Moreover, in 9 cases, virulent microorganisms were cultured in BCB only.

Culture-negative PJIs remains a concern for physicians treating patients with PJIs and in the last decade, many studies have been performed to improve culture techniques in order to increase culture yield. Several studies already demonstrated the clinical benefit of culturing synovial fluid and sonication in fluid in BCB by increasing the diagnostic yield and reducing the time to detection[1,2], but only a few studies evaluated its potential benefit for tissues samples. Peel et al., demonstrated an increased sensitivity of inoculating tissue samples in BCB compared to conventional cultures. Its benefit was most evident in patients with chronic infections.[3] In addition, Minassian et al. demonstrated a shorter time to positivity in which the majority of microorganisms were identified within 3 days.[2] This paper of the week conducted by van den Bijllaardt et al. adds to the current literature. In the studied cohort, four cases would be missed as infected if only clinical, serological and conventional cultures findings were used to diagnose PJI and multiple microorganisms would remain undetected with conventional methods. As in the current study, synovial fluid was not inoculated in BCB and sonication was not performed, it is unclear whether the inoculation of tissue samples in BCB will add to these methods. A recent study by Yan et al. could not find a significant difference in sensitivity of tissue culture in BCBs compared to sonicate fluid culture[4], and the use of BCB for tissue samples could be an alternative approach for centers that do not apply sonication.

References

[1]    Portillo ME, Salvadó M, Trampuz A, Siverio A, Alier A, Sorli L, et al. Improved diagnosis of orthopedic implant-associated infection by inoculation of sonication fluid into blood culture bottles. J Clin Microbiol 2015;53:1622–7. doi:10.1128/JCM.03683-14.

[2]    Minassian AM, Newnham R, Kalimeris E, Bejon P, Atkins BL, Bowler IC. Use of an automated blood culture system (BD BACTECTM) for diagnosis of prosthetic joint infections: easy and fast. BMC Infect Dis 2014;14:233. doi:10.1186/1471-2334-14-233.

[3]    Peel TN, Dylla BL, Hughes JG, Lynch DT, Greenwood-Quaintance KE, Cheng AC, et al. Improved Diagnosis of Prosthetic Joint Infection by Culturing Periprosthetic Tissue Specimens in Blood Culture Bottles. MBio 2016;7. doi:10.1128/mBio.01776-15.

[4]    Yan Q, Karau MJ, Greenwood-Quaintance KE, Mandrekar JN, Osmon DR, Abdel MP, et al. Comparison of Diagnostic Accuracy of Periprosthetic Tissue Culture in Blood Culture Bottles to That of Prosthesis Sonication Fluid Culture for Diagnosis of Prosthetic Joint Infection (PJI) by Use of Bayesian Latent Class Modeling and IDSA PJI Criteria for Classification. Journal of Clinical Microbiology 2018;56:e00319-18. doi:10.1128/JCM.00319-18.