Sonication culture improves microbiological diagnosis of modular megaprostheses

Abstract

Modular megaprostheses are known for high infection rates followed by high rates of revisions. Microbial biofilms growing adherently on prosthetic surfaces may inhibit the detection of the pathogens causing prosthetic joint infections. We sought to answer the following questions: Does sonication culture (SC) improve the microbiological diagnosis of periprosthetic infections of megaprostheses compared to conventional tissue culture (TC)? Which pathogens were detected on the surface of megaprostheses with either SC or TC and do the findings help to identify low-grade infections? Included were 31 patients with modular megaprostheses, whose implant had been explanted due to suspected joint infection or revision surgery. SCs were performed according to the protocol by Trampuz et al. The diagnosis of infection was evaluated according to the definition of the Musculoskeletal Infection Society. The sensitivity of SC was 91.3% compared to 52.2% for TC and the specificity was 100% for SC and TC (p = 0.004). Under preoperative antibiotic therapy, the sensitivity of SC was 83.3% while the sensitivity of TC was 50%. Without preoperative antibiotic therapy the sensitivity of SC was 100% compared to 54.5% for TC. In nine cases, SCs detected microorganisms, while TC was negative. Detected bacteria were Staphylococcus epidermidis in four, Micrococcus species in one, Finegoldia magna in one, Brevibacterium casei in one, Pseudomonas fluorescens in one, and Enterococcus faecium in one. SC is a reliable method for dislodging pathogens from orthopedic implants. The SC of modular megaprostheses showed significantly higher pathogen detection than the periprosthetic TC, especially for low virulence pathogens. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1383-1387, 2017.

The impact of sonication cultures when the diagnosis of prosthetic joint infection is inconclusive

“…By contrast, other authors have demonstrated that sonication fluid culture provides greater sensitivity than both tissue and synovial fluid cultures [ 17 , 18 , 22 , 23 ], possibly enhancing microbiological detection in biofilm-related orthopedic infections. Trampuz et al, were the first authors back in 2007 to found greater sensitivity for sonication cultures than for tissue cultures, and a non-statistically significant difference compared with synovial fluid cultures.…”

“…Both ICM 2018 and EBJIS endorsed sonication culture as an adjunct to tissue and synovial fluid cultures for diagnosing PJI [ 4 , 5 , 21 ]. In recent years, a number of authors have demonstrated that sonication fluid culture provides greater sensitivity than both tissue and synovial fluid cultures, reporting levels of 78–97% [ 17 , 18 , 22 , 23 ]. In contrast, others published their results showing a stand-in against culturing sonication fluid of retrieved implants [ 24 , 25 ].…”

Rapid analysis of bacterial composition in prosthetic joint infection by 16S rRNA metagenomic sequencing

“…19 In addition, cultures have high false-negative rates and are time consuming, as they might need one to two weeks for bacteria growth, especially in patients with low-grade infections. 35,36 Targeted cloning and subsequent Sanger sequencing of 16S rDNA has also been used in the past decade, for example to identify disease-associated bacteria in clinical specimens, such as dorsal tongue and bronchoalveolar lavage fluid, 37 enamel and dentin lesions, 38 and pus from brain abscesses. 39,40 Remarkably, this approach identified many bacteria that were not previously detected in these specimens, some of which were unculturable.…”

“…Third, 16S rRNA metagenomics is strongly susceptible to contamination from reagents and sample processing, 49 which may generate false positives or false negatives. 24,50 For instance, analysis of sonicated samples may be more sensitive than analysis of whole tissues, 36,51 but additional procedures and reagents for sonication and inefficient DNA extraction also increase the risk of contamination. 21,23,52 Indeed, removal of interference from contaminating DNA is a major challenge.…”

Antibiotic-laden cement wrap: A simple but effective way of treating patients with megaprosthesis infection

“…Hence, there are reports on the partial implant removal. 3,11 In our patients, we would also advise exchange for all detachable parts, in order to minimize the bacterial load and remove the biofilm, 20 if any. This may not be possible for the custom-made prostheses.…”