Sonication Fluid Culture Research Articles

Laboratory Diagnosis of Prosthetic Joint Infection, Part II

Prosthetic joint infection (PJI), although a rare complication of primary or revision arthroplasty, is reported more frequently as the number patients undergoing arthroplasty increases. Accurate diagnosis of PJI is essential for adequate management and outcome. Although multiple tests have been applied, in some cases, differentiation of PJI from aseptic loosening of the prosthesis remains a challenge. Here, we review the current diagnostic laboratory modalities used for the diagnosis PJI. In Part I of this two-part article, components of the preoperative evaluation of the patient and the histology of the intraoperative evaluation were discussed. Part II of the article discusses the remaining components of the intraoperative evaluation, including periprosthetic tissue and sonicate fluid cultures. In addition, recent investigational approaches for the diagnosis of PJI, antimicrobial susceptibility testing, and management of PJIs are reviewed.

Sonication cultures of explanted components as an add‐on test to routinely conducted microbiological diagnostics improve pathogen detection

The purpose of this study was to improve the pathogen detection in prosthetic joint infections, particularly to evaluate the feasibility of the sonication culture method in the clinical routine. Explanted components of all patients with presumptive prosthetic or implant infection were sonicated separately in sterile containers to dislodge the adherent bacteria from the surfaces and cultured. The results of sonication culture were compared to the conventional tissue culture. We investigated 60 consecutive patients with loosening of the prostheses or implants Forty patients had septic and 20 aseptic loosening (24 knee prostheses, 21 hip prostheses, 6 mega-prostheses, 2 shoulder prostheses, 6 osteosynthesis, 1 spinal instrumentation). The sensitivity of sonication fluid culture was 83.3%, of single positive tissue culture was 72.2% and 61.1% when two or more cultures yielded the same microorganism. In patients receiving antibiotic therapy the sensitivity was 65.9%, 57.5%, and 42.5%, respectively. Pathogens detected in a single tissue culture as well as in sonication culture yielded a significantly higher rate of prosthetic infection than conventional tissue culture alone (p = 0.008), even in patients receiving continuous antibiotic therapy before explantation (p = 0.016). The sonication method represents an essential add-on in pathogen detection compared to conventional tissue culture.

A Biofilm Approach to Detect Bacteria on Removed Spinal Implants

This is a prospective study comparing the diagnosis of spinal implant infection by conventional peri-implant tissue culture with a technique which uses a combination of vortexing and bath sonication to dislodge bacteria growing as a biofilm on the surface of retrieved spinal implants. We hypothesized that the biofilm-sampling technique would be more sensitive than peri-implant tissue culture. Culture of peri-implant tissue is inaccurate for the diagnosis of orthopedic device-related infection; cultures taken from the implant may be more sensitive. We have developed a technique which uses vortexing-bath sonication to sample bacterial biofilms on the surface of retrieved hip and knee implants, and shown that it is more sensitive than peri-prosthetic tissue culture for the microbiologic diagnosis of prosthetic knee, hip, and shoulder infection. We compared peri-implant tissue culture to the vortexing-bath sonication technique which samples bacterial biofilm on the surface of retrieved spinal implants, for the diagnosis of spinal implant infection. In addition, we compared detection of Staphylococcus and Propionibacterium acnes by rapid cycle real-time polymerase chain reaction with culture of sonicate fluid. A total of 112 subjects were studied; 22 had spinal implant infection. The sensitivities of peri-implant tissue and sonicate fluid culture were 73% and 91% (P = 0.046), and the specificities were 93% and 97%, respectively. P. acnes and coagulase-negative staphylococci were the most frequent microorganisms detected among subjects with spinal implant infection, with P. acnes detected in 56 and 45%, and coagulase-negative staphylococci detected in 31 and 40% of peri-implant tissue and sonicate fluid cultures, respectively. Compared with the culture of sonicate fluid, polymerase chain reaction was 100 and 67% sensitive for the detection of culture-positive Staphylococcus and P. acnes spinal implant infection, respectively. Implant sonication followed by culture is more sensitive than peri-implant tissue culture for the microbiologic diagnosis of spinal implant infection.

Bacterial Colonization and Infection of Electrophysiological Cardiac Devices Detected With Sonication and Swab Culture

Electrophysiological cardiac devices are increasingly used. The frequency of subclinical infection is unknown. We investigated all explanted devices using sonication, a method for detection of microbial biofilms on foreign bodies. Consecutive patients in whom cardiac pacemakers and implantable cardioverter/defibrillators were removed at our institution between October 2007 and December 2008 were prospectively included. Devices (generator and/or leads) were aseptically removed and sonicated, and the resulting sonication fluid was cultured. In parallel, conventional swabs of the generator pouch were performed. A total of 121 removed devices (68 pacemakers, 53 implantable cardioverter/defibrillators) were included. The reasons for removal were insufficient battery charge (n=102), device upgrading (n=9), device dysfunction (n=4), or infection (n=6). In 115 episodes (95%) without clinical evidence of infection, 44 (38%) grew bacteria in sonication fluid, including Propionibacterium acnes (n=27), coagulase-negative staphylococci (n=11), Gram-positive anaerobe cocci (n=3), Gram-positive anaerobe rods (n=1), Gram-negative rods (n=1), and mixed bacteria (n=1). In 21 of 44 sonication-positive episodes, bacterial counts were significant (>or=10 colony-forming units/mL of sonication fluid). In 26 sterilized controls, sonication cultures remained negative in 25 cases (96%). In 112 cases without clinical infection, conventional swab cultures were performed: 30 cultures (27%) were positive, and 18 (60%) were concordant with sonication fluid cultures. Six devices and leads were removed because of infection, growing Staphylococcus aureus, Streptococcus mitis, and coagulase-negative staphylococci in 6 sonication fluid cultures and 4 conventional swab cultures. Bacteria can colonize cardiac electrophysiological devices without clinical signs of infection.

Improved detection of microbial ureteral stent colonisation by sonication

The diagnosis of microbial ureteral stent colonisation (MUSC) is difficult, since routine diagnostic techniques do not accurately detect microorganisms embedded in biofilms. New methods may improve diagnostic yield and understanding the pathophysiology of MUSC. The aim of the present study was to evaluate the potential of sonication in the detection of MUSC and to identify risk factors for device colonisation. Four hundred and eight polyurethane ureteral stents of 300 consecutive patients were prospectively evaluated. Conventional urine culture (CUC) was obtained prior to stent placement and device removal. Sonication was performed to dislodge adherent microorganisms. Data of patient sex and age, indwelling time and indication for stent placement were recorded. Sonicate-fluid culture detected MUSC in 36%. Ureteral stents inserted during urinary tract infection (UTI) were more frequently colonised (59%) compared to those placed in sterile urine (26%; P<0.001). Female sex (P<0.001) and continuous stenting (P<0.005) were significant risk factors for MUSC; a similar trend was observed in patients older than 50 years (P=0.16). MUSC and indwelling time were positively correlated (P<0.005). MUSC was accompanied by positive CUC in 36%. Most commonly isolated microorganisms were Coagulase-negative staphylococci (18.3%), Enterococci (17.9%) and Enterobacteriaceae (16.9%). Sonication is a promising approach in the diagnosis of MUSC. Significant risk factors for MUSC are UTI at the time of stent insertion, female sex, continuous stenting and indwelling time. CUC is a poor predictor of MUSC. The clinical relevance of MUSC needs further evaluation to classify isolated microorganism properly as contaminants or pathogens.

Improving Microbiological Diagnosis of Prosthetic Joint–Related Infections

Identifying the pathogen responsible for prosthetic joint–related infections is often difficult, particularly when cultures are not obtained until after patients have already received antimicrobial therapy. Previous studies have shown that diagnostic yield improves with sonication of resected prosthetic joints and culture of the sonication fluid. Might molecular …

Sonication of Removed Breast Implants for Improved Detection of Subclinical Infection

Capsular fibrosis is a severe complication after breast implantation with an uncertain etiology. Microbial colonization of the prosthesis is hypothesized as a possible reason for the low-grade infection and subsequent capsular fibrosis. Current diagnostic tests consist of intraoperative swabs and tissue biopsies. Sonication of removed implants may improve the diagnosis of implant infection by detachment of biofilms from the implant surface. Breast implants removed from patients with Baker grades 3 and 4 capsular contracture were analyzed by sonication, and the resulting sonication fluid was quantitatively cultured. This study investigated 22 breast implants (6 implants with Baker 3 and 16 implants with Baker 4 capsular fibrosis) from 13 patients. The mean age of the patients was 49 years (range, 31-76 years). The mean implant indwelling time was 10.4 years (range, 3 months to 30 years). Of the 22 implants, 12 were used for breast reconstruction and 10 for aesthetic procedures. The implants were located subglandularly (n = 12), submuscularly (n = 6), and subcutaneously (n = 4). Coagulase-negative staphylococci, Propionibacterium acnes, or both were detected in the sonication fluid cultures of nine implants (41%), eight of which grew significant numbers of microorganisms (>100 colonies/ml of sonication fluid). Sonication detected bacteria in 41% of removed breast implants. The identified bacteria belonged to normal skin flora. Further investigation is needed to determine any causal relation between biofilms and capsular fibrosis.

Microbiologic Diagnosis of Prosthetic Shoulder Infection by Use of Implant Sonication

We recently described a sonication technique for the diagnosis of prosthetic knee and hip infections. We compared periprosthetic tissue culture to implant sonication followed by sonicate fluid culture for the diagnosis of prosthetic shoulder infection. One hundred thirty-six patients undergoing arthroplasty revision or resection were studied; 33 had definite prosthetic shoulder infections and 2 had probable prosthetic shoulder infections. Sonicate fluid culture was more sensitive than periprosthetic tissue culture for the detection of definite prosthetic shoulder infection (66.7 and 54.5%, respectively; P = 0.046). The specificities were similar (98.0% and 95.1%, respectively; P = 0.26). Propionibacterium acnes was the commonest species detected among culture-positive definite prosthetic shoulder infection cases by periprosthetic tissue culture (38.9%) and sonicate fluid culture (40.9%). All subjects from whom P. acnes was isolated from sonicate fluid were male. We conclude that sonicate fluid culture is useful for the diagnosis of prosthetic shoulder infection.

Sonication of Removed Hip and Knee Prostheses for Diagnosis of Infection

Culturing of samples of periprosthetic tissue is the standard method used for the microbiologic diagnosis of prosthetic-joint infection, but this method is neither sensitive nor specific. In prosthetic-joint infection, microorganisms are typically present in a biofilm on the surface of the prosthesis. We hypothesized that culturing of samples obtained from the prosthesis would improve the microbiologic diagnosis of prosthetic-joint infection. We performed a prospective trial comparing culture of samples obtained by sonication of explanted hip and knee prostheses to dislodge adherent bacteria from the prosthesis with conventional culture of periprosthetic tissue for the microbiologic diagnosis of prosthetic-joint infection among patients undergoing hip or knee revision or resection arthroplasty. We studied 331 patients with total knee prostheses (207 patients) or hip prostheses (124 patients); 252 patients had aseptic failure, and 79 had prosthetic-joint infection. With the use of standardized nonmicrobiologic criteria to define prosthetic-joint infection, the sensitivities of periprosthetic-tissue and sonicate-fluid cultures were 60.8% and 78.5% (P<0.001), respectively, and the specificities were 99.2% and 98.8%, respectively. Fourteen cases of prosthetic-joint infection were detected by sonicate-fluid culture but not by prosthetic-tissue culture. In patients receiving antimicrobial therapy within 14 days before surgery, the sensitivities of periprosthetic tissue and sonicate-fluid culture were 45.0% and 75.0% (P<0.001), respectively. In this study, culture of samples obtained by sonication of prostheses was more sensitive than conventional periprosthetic-tissue culture for the microbiologic diagnosis of prosthetic hip and knee infection, especially in patients who had received antimicrobial therapy within 14 days before surgery.

Sonication of Explanted Prosthetic Components in Bags for Diagnosis of Prosthetic Joint Infection Is Associated with Risk of Contamination

Explanted orthopedic implants from 54 patients with aseptic failure and 24 patients with prosthetic knee or hip infection were sonicated in polyethylene bags. The sensitivities of periprosthetic tissue and sonicate fluid cultures for the diagnosis of prosthetic joint infection were 54% and 75%, whereas the specificities were 98% and 87%, respectively. Sonication in bags improved bacterial recovery from the surface of orthopedic implants; however, it lacked specificity, due to bag leakage.