Positive Tissue Cultures Research Articles

Synovial fluid leukocytes as diagnostic marker in periprosthetic shoulder infection

BackgroundLimited data exist regarding the diagnostic accuracy of synovial fluid leukocyte count (SFLC) in diagnosing periprosthetic shoulder infection (PSI). The main objective of this study was to determine the diagnostic value of leukocyte count at a common threshold of 3 cells/nL and the optimal cut-off value. MethodsPatients, who underwent shoulder arthroplasty revision surgery and aspiration with SFLC between 2012 and 2023 were retrospectively included. The International Consensus Meeting (ICM) 2018 definition was used to characterize infection status for SFLC threshold and synovial fluid neutrophil percentage (SFNP). Sensitivity and specificity were presented using cross tabulation. The area under the curve was calculated, and the optimal cut-off was determined using maximized Youden Index. Results35 cases with an average age of 71 years (43% male) were included in our study. At a threshold of 3 cells/nL, SFLC showed a sensitivity of 70% and specificity of 83%. The corresponding positive and negative predictive values (PPV, NPV) were 89% and 59%. We found the optimal cut-off for our cohort at 4.7 cells/nL, increasing specificity to 92% while maintaining sensitivity at 70% (PPV = 94%, NPV = 61%). SFNP at a cut-off of 80% demonstrated 50% sensitivity and 91% specificity, with corresponding PPV and NPV of 92% and 48%. The optimum threshold for SFNP was 54%, which had a sensitivity of 77% and a specificity of 64%, as well as a PPV of 81%, and NPV of 58%. The area under the curve was 0.72 for SFLC and 0.74 for SFNP. Sonication detected pathogens in 63% of cases, while 57% of all cases showed positive tissue cultures and 43% positive aspirate cultures. Especially the most frequently found microorganism, Cutibacterium acnes, was detected less often in aspirate culture. ConclusionsSFLC shows good specificity but moderate sensitivity for diagnosing PSI when using a threshold of 4.7 cells/nL. Therefore, it can serve as a confirmatory test for diagnosing PSI but not for ruling out infection.

Above-knee amputation shows higher complication and mortality rates in line with lower functional outcome compared to knee arthrodesis in severe periprosthetic joint infection

AimsIn cases of severe periprosthetic joint infection (PJI) of the knee, salvage procedures such as knee arthrodesis (KA) or above-knee amputation (AKA) must be considered. As both treatments result in limitations in quality of life (QoL), we aimed to compare outcomes and factors influencing complication rates, mortality, and mobility.MethodsPatients with PJI of the knee and subsequent KA or AKA between June 2011 and May 2021 were included. Demographic data, comorbidities, and patient history were analyzed. Functional outcomes and QoL were prospectively assessed in both groups with additional treatment-specific scores after AKA. Outcomes, complications, and mortality were evaluated.ResultsA total of 98 patients were included, 52 treated with arthrodesis and 47 with AKA. The mean number of revision surgeries between primary arthroplasty and arthrodesis or AKA was 7.85 (SD 5.39). Mean follow-up was 77.7 months (SD 30.9), with a minimum follow-up of two years. Complications requiring further revision surgery occurred in 11.5% of patients after arthrodesis and in 37.0% of AKA patients. Positive intraoperative tissue cultures obtained during AKA was significantly associated with the risk of further surgical revision. Two-year mortality rate of arthrodesis was significantly lower compared to AKA (3.8% vs 28.3%), with age as an independent risk factor in the AKA group. Functional outcomes and QoL were better after arthrodesis compared to AKA. Neuropathic pain was reported by 19 patients after AKA, and only 45.7% of patients were fitted or were intended to be fitted with a prosthesis. One-year infection-free survival after arthrodesis was 88.5%, compared to 78.5% after AKA.ConclusionAbove-knee amputation in PJI results in high complication and mortality rates and poorer functional outcome compared to arthrodesis. Mortality rates after AKA depend on patient age and mobility, with most patients not able to be fitted with a prosthesis. Therefore, arthrodesis should be preferred whenever possible if salvage procedures are indicated.Cite this article: Bone Joint J 2024;106-B(7):669–679.

Outcomes in Patients With Heel Ulcerations that Underwent Below the Knee Amputations Versus Vertical Contour Calcanectomy: Importance of Selection Criteria

The aim of the study was to compare preoperative factors and postoperative outcomes in patients with heel ulcerations that primarily had a transtibial (below the knee) amputation (N = 38) versus vertical contour calcanectomy (n = 62). The groups had no statistical difference between their Charlson Comorbidity Index Score, a prognostic score of 10-year survival in patients with multiple comorbidities. The odds of primary closure were 21.1 times higher in patients that underwent below knee amputation compared to patients that underwent vertical contour calcanectomy (OR 21.1 [95% CI 3.89-114.21]). The odds of positive soft tissue culture at time of closure were 17.1 times higher for patients that underwent vertical contour calcanectomy (OR 17.1 [95% CI 5.40-54.16]). The odds of a patent posterior tibial artery were 3.3 times higher for patients that underwent vertical contour calcanectomy (OR 3.3 [95% 1.09-10.09]). The secondary aim of the study was to evaluate preoperative factors and postoperative outcomes in patients with failed vertical contour calcanectomy, defined as needing a below knee amputation. The odds of vertical contour calcanectomy failure was 13.7 times higher in male patients (OR 13.7 [95% CI 1.80-107.60]). Vertical contour calcanectomy failure was 5.7 times higher in patients with renal disease (OR 5.7 [95% CI 1.10-30.30]), and vertical contour calcanectomy failure was 16.1 times higher for patients who needed additional surgery post closure (OR 16.1 [95% CI 1.40-183.20]).

Acute Interstitial Inflammation on Skin Biopsies and Positive Tissue Cultures in Cellulitis Patients Are Associated a Worse Prognosis.

Cellulitis is a significant public health burden and lacks a gold standard for diagnosis. Up to 1/3 of patients are incorrectly diagnosed. The skin biopsy has been proposed as the gold standard. In this study, we evaluate the histopathologic characteristics and tissue culture positivity of biopsies in patients diagnosed with cellulitis seen by our inpatient dermatology consultation service. This retrospective cohort study examined patients who were hospitalized with a skin and soft tissue infection at our institution between 2011 and 2020 and underwent a skin biopsy. Those with a positive tissue culture were more likely to die within 30 days compared with those with negative tissue cultures (26% vs. 6%, P = 0.048). Patients who died within 30 days were more likely to have acute interstitial inflammation as a feature on histopathology (38%, P = 0.03). Single institutional design, unintentional exclusion of patients with organism-specific diagnosis, and selection for a medically complex patient population because of the nonroutine collection of biopsies. Positive tissue cultures and histopathology showing acute interstitial space inflammation on skin and soft tissue infection (SSTI) biopsies are associated with increased mortality and thus may serve as indicators of poor prognosis.

Developing a Novel Murine Meningococcal Meningitis Model Using a Capsule-Null Bacterial Strain.

Neisseria meningitidis (meningococcus) is a Gram-negative bacterium that colonises the nasopharynx of about 10% of the healthy human population. Under certain conditions, it spreads into the body, causing infections with high morbidity and mortality rates. Although the capsule is the key virulence factor, unencapsulated strains have proved to possess significant clinical implications as well. Meningococcal meningitis is a primarily human infection, with limited animal models that are dependent on a variety of parameters such as bacterial virulence and mouse strain. In this study, we aimed to develop a murine Neisseria meningitidis meningitis model to be used in the study of various antimicrobial compounds. We used a capsule-deficient Neisseria meningitidis strain that was thoroughly analysed through various methods. The bacterial strain was incubated for 48 h in brain-heart infusion (BHI) broth before being concentrated and injected intracisternally to bypass the blood-brain barrier in CD-1 mice. This prolonged incubation time was a key factor in increasing the virulence of the bacterial strain. A total of three more differently prepared inoculums were tested to further solidify the importance of the protocol (a 24-h incubated inoculum, a diluted inoculum, and an inactivated inoculum). Antibiotic treatment groups were also established. The clinical parameters and number of deaths were recorded over a period of 5 days, and comatose mice with no chance of recovery were euthanised. The bacterial strain was confirmed to have no capsule but was found to harbour a total of 56 genes coding virulence factors, and its antibiotic susceptibility was established. Meningitis was confirmed through positive tissue culture and histological evaluation, where specific lesions were observed, such as perivascular sheaths with inflammatory infiltrate. In the treatment groups, survival rates were significantly higher (up to 81.25% in one of the treatment groups compared to 18.75% in the control group). We managed to successfully develop a cost-efficient murine (using simple CD-1 mice instead of expensive transgenic mice) meningococcal meningitis model using an unencapsulated strain with a novel method of preparation.

Outcomes Following Different Management of Mycotic Infrarenal Abdominal Aortic Aneurysms.

The objective was to present our experience on managing mycotic infrarenal abdominal aortic aneurysm (MIAAA) through a retrospective cohort study. Data of patients with MIAAA managed in our center from July 2016 to October 2022 were retrospectively analyzed. The diagnosis of MIAAA was made based on: (1) preoperative clinical signs of infection; (2) elevated serologic infection parameters; (3) para-aneurysmal infection features on enhanced computed tomography; and (4) positive blood or tissue cultures. All the patients received standard antibiotic therapy. Surgical management including endovascular aneurysm repair (EVAR), initial EVAR followed by open re-operation, and initial open surgical repair (OSR) were conducted according to disease seriosity, physical condition, and patient's will. Infection index and clinical outcome were evaluated during the follow-up time. A total of 23 patients (21 men; averaged=66.3 years, range=49-79 years) were included, with a mean follow-up time of 19.9 months (range=1-75 months). Bacteria culture from blood or tissue specimen was positive in 15 patients (Salmonella, n=8; Escherichia coli, n=3; methicillin-sensitive Staphylococcus aureus [MSSA], n=1; Klebsiella pneumoniae, n=1; Staphylococcus epidermidis, n=1; Mycobacterium tuberculosis, n=1). Seven patients received OSR as the initial surgical intervention, whereas 14 patients chose EVAR instead. The 2 conservatively managed patients (refused surgery) died within 30 days. The 7 patients who received initial OSR survived till now. Among the 14 patients who underwent initial EVAR, infection deteriorated without exception (14/14, 100%). Three of these patients refused re-operation and died within 6 months. Eleven patients received secondary surgical intervention (10 cases of aneurysm and endograft resection, thorough debridement, subclavian to bi-femoral artery bypass, or in situ aorta reconstruction; 1 case of laparoscopic debridement) and 7 survived the follow-up time. The overall mortality rate was 39.1% (9/23). The mortality rates differed greatly following different intervention methods (merely antibiotic management, 100%; initial open operation, 0%; initial EVAR without secondary operation, 100%; initial EVAR plus secondary operation, 36.4%). Open surgical repair is still the first choice for hemodynamically stable and low-risk patients. Merely EVAR is related with disastrous results, which should be reserved as a temporary alternative for patients with ruptured aneurysms, hemodynamic instability or high surgical risk, and followed by timely secondary OSR. The management of mycotic or primary-infected aortic aneurysm is challenging; treatment remains controversial. Our center has reviewed our experience over the past 6 years and found that open surgical repair is still the first choice for hemodynamically stable and low-risk patients. Merely endovascular aneurysm repair (EVAR) is related with disastrous results, which should be reserved as a temporary alternative for patients with ruptured aneurysms, hemodynamic instability or high surgical risk, and followed by timely secondary open surgical repair.

Intraoperative calprotectin lateral flow immunoassay can assist decision-making between one- and two-stage revision total hip arthroplasty for patients with suspected periprosthetic joint infection.

Accurate diagnosis of chronic periprosthetic joint infection (PJI) presents a significant challenge for hip surgeons. Preoperative diagnosis is not always easy to establish, making the intraoperative decision-making process crucial in deciding between one- and two-stage revision total hip arthroplasty (THA). Calprotectin is a promising point-of-care novel biomarker that has displayed high accuracy in detecting PJI. We aimed to evaluate the utility of intraoperative calprotectin lateral flow immunoassay (LFI) in THA patients with suspected chronic PJI. The study included 48 THAs in 48 patients with a clinical suspicion of PJI, but who did not meet European Bone and Joint Infection Society (EBJIS) PJI criteria preoperatively, out of 105 patients undergoing revision THA at our institution for possible PJI between November 2020 and December 2022. Intraoperatively, synovial fluid calprotectin was measured with LFI. Cases with calprotectin levels ≥ 50 mg/l were considered infected and treated with two-stage revision THA; in negative cases, one-stage revision was performed. At least five tissue cultures were obtained; the implants removed were sent for sonication. Calprotectin was positive (≥ 50 mg/l) in 27 cases; out of these, 25 had positive tissue cultures and/or sonication. Calprotectin was negative in 21 cases. There was one false negative case, which had positive tissue cultures. Calprotectin showed an area under the curve of 0.917, sensitivity of 96.2%, specificity of 90.9%, positive predictive value of 92.6%, negative predictive value of 95.2%, positive likelihood ratio of 10.6, and negative likelihood ratio of 0.04. Overall, 45/48 patients were correctly diagnosed and treated by our algorithm, which included intraoperative calprotectin measurement. This yielded a 93.8% concordance with postoperatively assessed EBJIS criteria. Calprotectin can be a valuable tool in facilitating the intraoperative decision-making process for cases in which chronic PJI is suspected and diagnosis cannot be established preoperatively.

Percutaneous Disc Biopsy versus Bone Biopsy for the Identification of Infectious Agents in Osteomyelitis/Discitis

PurposeTo determine whether sampling of the disc or bone is more likely to yield positive tissue culture results in patients with vertebral discitis and osteomyelitis (VDO). Materials and MethodsRetrospective review was performed of consecutive patients who underwent vertebral disc or vertebral body biopsy at a single institution between February 2019 and May 2023. Inclusion criteria were age ≥18 years, presumed VDO on spinal magnetic resonance (MR) imaging, absence of paraspinal abscess, and technically successful percutaneous biopsy with fluoroscopic guidance. The primary outcome was a positive biopsy culture result, and secondary outcomes included complications such as nerve injury and segmental artery injury. ResultsSixty-six patients met the inclusion criteria; 36 patients (55%) underwent disc biopsy, and 30 patients (45%) underwent bone biopsy. Six patients required a repeat biopsy for an initially negative culture result. No significant demographic, laboratory, antibiotic administration, or pain medication use differences were observed between the 2 groups. Patients who underwent bone biopsy were more likely to have a history of intravenous drug use (26.7%) compared with patients who underwent disc biopsy (5.5%; P = .017). Positive tissue culture results were observed in 41% of patients who underwent disc biopsy and 15% of patients who underwent bone biopsy (P = .016). No vessel or nerve injuries were detected after procedure in either group. ConclusionsPercutaneous disc biopsy is more likely to yield a positive tissue culture result than vertebral body biopsy in patients with VDO.

Chronic disseminated candidiasis in a patient with acute leukemia - an illustrative case and brief review for clinicians

Chronic disseminated candidiasis (CDC) is a severe but rarely seen fungal infection presenting in patients with hematologic malignancies after a prolonged duration of neutropenia. A high index of suspicion is required to diagnose CDC as standard culture workup is often negative. While tissue biopsy is the gold standard of diagnosis, it is frequently avoided in patients with profound cytopenias and increased bleeding risks. A presumptive diagnosis can be made in patients with recent neutropenia, persistent fevers unresponsive to antibiotics, imaging findings of hypoechoic, non-rim enhancing target-like lesions in the spleen and liver, and mycologic evidence. Here, we describe the case of an 18-year-old woman with relapsed B-cell acute lymphoblastic leukemia treated with re-induction chemotherapy who subsequently developed CDC with multi-organ involvement. The diagnosis was made based on clinical and radiologic features with positive tissue culture from a skin nodule and hepatic lesion. The patient was treated for a total course of 11 months with anti-fungal therapy, most notably amphotericin B and micafungin, and splenectomy. After initial diagnosis, the patient was monitored with monthly CT abdomen imaging that showed disease control after 5 months of anti-fungal therapy and splenectomy. The diagnosis, treatment, and common challenges of CDC are outlined here to assist with better understanding, diagnosis, and treatment of this rare condition.

Comparative study of tissue culture and sensitivity versus swab culture and sensitivity of microorganisms in the healing of diabetic foot ulcers

This prospective observational study, conducted at the Department of General Surgery, SRM Medical College and Hospital, aimed to assess the effectiveness of tissue culture and sensitivity compared to swab culture and sensitivity in the healing of diabetic foot ulcers through antibiotic sensitivity of microorganisms. Between May 2016 and August 2017, 160 subjects with diabetic foot ulcers were randomly assigned treatment based on either swab or tissue culture findings. Patients were followed at 15-day intervals for up to 60 days. Results showed positive swab cultures in 76.88% and positive tissue cultures in 92.50% of the study population. The most prevalent organism in swab cultures was Proteus (14.38%), while Pseudomonas (16.88%) dominated in tissue cultures. The cumulative proportion of subjects developing granulation tissue was faster in the tissue culture group, reaching 57.50% at 15 to 30 days and 99% at 31 to 45 days. The swab culture group exhibited proportions of 48.80%, 75%, and 93.80% at the same intervals. In conclusion, diabetic foot ulcer treatment based on tissue culture showed slightly faster healing rates compared to swab culture. However, both groups achieved good ulcer healing within the 60-day follow-up period. These findings emphasize the importance of choosing an appropriate culture method for effective management of diabetic foot ulcers.

Intramedullary Positive Tissue Culture Increases the Risk of Reinfection Following One-Stage Septic Revision Total Knee Arthroplasty

BackgroundIntraoperative acquisition of representative tissue samples is essential during revision arthroplasty of the infected total knee arthroplasty (TKA). While the number of intraoperative tissue samples needed to identify the organism is well described in the literature, there is still a paucity of evidence regarding the location of positive intraoperative samples and their correlation to postoperative outcomes. MethodsThere were forty-two patients who had septic failure following one-stage revision TKA for periprosthetic joint infection who were identified between January 2009 and December 2017. They were matched to a control group of patients who had successful one-stage revision TKA without septic failure. The location of positive intraoperative tissue samples was categorized as: 1) soft tissue; 2) interface between bone and prosthesis; and 3) intramedullary (IM). Chi-square, Student’s t-, and Wilcoxon Mann-Whitney U-tests were used as appropriate. Univariate and multivariate logistic regression analyses were performed to evaluate predictors of septic failure. ResultsWeight > 100 kilograms (P = .033), higher Charlson Comorbidity Index (P < .001), and positive IM cultures (P < .001) were associated with a higher risk of reinfection after one-stage revision TKA. A positive IM sample carried a nearly five-fold increase in odds of reinfection (odds ratio 4.86, 95% confidence interval 1.85 to 12.78, P = .001). ConclusionsA positive IM culture sample is significantly associated with septic failure after one-stage exchange for periprosthetic joint infection of the knee. Patients who had positive IM cultures may benefit from longer postoperative antibiotic therapy for the treatment of one-stage exchange arthroplasty to minimize the risk of reinfection.

The microbiology of periprosthetic joint infections as revealed by sonicate cultures in Korea: Routine use of fungal and mycobacterial cultures is necessary?

Although sonication is a valuable diagnostic tool for periprosthetic joint infections (PJI), it is not commonly utilized. We analyzed sonicate and intraoperative tissue culture results obtained from three hospitals to define the microbial etiology of PJIs in Korea. Furthermore, we investigated necessity of conducting regular fungal and mycobacterial cultures. We retrospectively analyzed data for patients with suspected orthopedic-related infections between 2017 and 2022, who had undergone prostheses removal surgery. We included 193 patients with suspected PJIs, and bacterial (n = 193), fungal (n = 193), and mycobacterial (n = 186) cultures were conducted on both sonicate and intraoperative tissue samples. The diagnosis of PJI was based on the European Bone and Joint Infection Society (EBJIS) criteria. Out of 193 patients, 121 (62.7%) had positive sonicate cultures, while 112 (58.0%) had positive periprosthetic tissue cultures. According to EBJIS criteria, a total of 181 patients were diagnosed with PJI, and 141 patients received microbiological confirmation through sonicate fluid culture or tissue culture. Of the 181 patients, 28 were classified with acute PJI (within 3 months of implantation) and 153 with chronic PJI. Among 141 patients, staphylococci were the most common organisms, accounting for 51.8% of cases, followed by Gram-negative organisms (15.6%), fungus (8.5%), and mycobacteria (3.5%). Nearly 91.7% of fungal isolates were Candida species, which also grew in bacterial cultures. In total, 11 cases cultured positive only in tissue culture, whereas 20 cases cultured positive only in sonicate culture. The antibiotic treatment plans were adjusted according to culture results. Utilizing sonicate culture has greatly assisted in identifying pathogens responsible for chronic indolent PJIs, allowing suitable antimicrobial treatment. Based on few cases involving non-Candida and mycobacterial infections, it appears that routine fungal and mycobacterial cultures may not be necessary.

Is an isolated positive sonication fluid culture in revision arthroplasties clinically relevant?

ObjectivesThe aim of this study was to investigate the clinical relevance of an isolated positive sonication fluid culture (SFC) in patients who underwent revision surgery of a prosthetic joint. We hypothesized that cases with a positive SFC have a higher rate of infection during follow-up compared with controls with a negative SFC. MethodsThis retrospective multicentre observational study was performed within the European Study Group of Implant-Associated Infections. All patients who underwent revision surgery of a prosthetic joint between 2013 and 2019 and had a minimum follow-up of 1 year were included. Patients with positive tissue cultures or synovial fluid cultures were excluded from the study. ResultsA total of 95 cases (positive SFC) and 201 controls (negative SFC) were included. Infection during follow-up occurred in 12 of 95 cases (12.6%) versus 14 of 201 controls (7.0%) (p = 0.125). In all, 79.8% of cases were with treated with antibiotics (76/95). Of the non-treated cases, 89% (17/19) had a positive SFC with a low virulent microorganism. When solely analysing patients who were not treated with antibiotics, 16% of the cases (3/19) had an infection during follow-up versus 5% of the controls (9/173) (p = 0.08). DiscussionAlthough not statistically significant, infections were almost twice as frequent in patients with an isolated positive SFC. These findings require further exploration in larger trials and to conclude about the potential benefit of antibiotic treatment in these cases.

Arthroscopic tissue biopsy as a preoperative diagnostic test for periprosthetic shoulder arthroplasty infections: a systematic review and meta-analysis.

The diagnosis of periprosthetic infection in shoulder arthroplasty remains a challenge. Conventional methods for evaluating periprosthetic joint infections are poor because of lower-virulence organisms affecting the shoulder. The aim of our systematic review was to evaluate the diagnostic accuracy of preoperative arthroscopic tissue cultures compared with tissue biopsy samples obtained at the time of revision surgery. We conducted a systematic search of the MEDLINE, Embase, and Cochrane Central databases. The inclusion criteria consisted of studies that used arthroscopy to obtain preoperative tissue cultures for the diagnosis of shoulder arthroplasty infections. Studies were excluded if they obtained non-arthroscopic tissue samples. We reported the sensitivity, specificity, positive predictive value, and negative predictive value. Culture findings from the arthroscopic biopsy samples were also compared with conventional tests of fluoroscopy-guided joint aspiration and serum inflammatory marker testing (positive erythrocyte sedimentation rate or C-reactive protein) within the included studies. A meta-analysis was performed to assess the overall diagnostic accuracy of the studies. Our search strategy yielded 795 potentially relevant publications; 572 underwent title and abstract screening, and 14 studies underwent full-text review, of which 7 were included in our systematic review. The studies represented a balance of shoulder arthroplasty types, including anatomic total shoulder arthroplasty (n=75, 38%), reverse total shoulder arthroplasty (n=60, 30%), and hemiarthroplasty (n=64, 32%). There were 56 of 120 arthroscopic procedures that returned positive tissue culture findings compared with 64 of 157 positive open biopsy culture findings obtained from revision surgery. The meta-analysis total for sensitivity and specificity for all studies combined indicated that arthroscopic tissue cultures (0.76 [95% confidence interval (CI), 0.57-0.88] and 0.91 [95% CI, 0.79-0.97], respectively) were superior to both aspiration (0.15 [95% CI, 0.03-0.48] and 0.93 [95% CI, 0.65-0.99], respectively) and a positive erythrocyte sedimentation rate or C-reactive protein level (0.14 [95% CI, 0.02-0.62] and 0.83 [95% CI, 0.56-0.95], respectively) in diagnosing periprosthetic shoulder infections. Our systematic review demonstrated that preoperative arthroscopic tissue biopsy used for microbiology cultures accurately predicts intraoperative culture findings obtained during revision surgery with high sensitivity and specificity. Additionally, arthroscopy appears to be superior to conventional techniques of joint aspiration and inflammatory marker testing. Therefore, arthroscopic tissue cultures may be an emerging useful tool to help guide the management of periprosthetic infections in shoulder arthroplasty.

THE DIAGNOSTIC ACCURACY OF INTRAOPERATIVE SYNOVIAL FLUID CALPROTECTIN IN SUSPECTED LOW-GRADE PERIPROSTHETIC HIP JOINT INFECTIONS

Pre-operative definitive diagnosis of infection in painful total hip arthroplasty (THA) is not always easy to be established, making the intra-operative decision-making process crucial in management of revision hip surgery. Calprotectin is a promising point-of-care novel biomarker that has displayed high accuracy in detecting PJIs.From November 2020 to December 2022, 105 patients with painful primary THA were treated with revision THA in 3 orthopaedic departments. Pre-operatively, 23 were considered infected and treated with two-stage revision THA. The remaining 82 were likely infected according to the 2019 EBJIS criteria. The suspicion of low-grade infection was based on clinical (rest and/or night pain), laboratory (CRP, ESR, WBC – normal or slightly elevated) and radiological evaluation (loosening). Hip aspiration under CT imaging was performed in these cases and 34 of them yielded positive culture and were treated with two-stage revision. Aspiration was ineffective in the remaining 48 cases (33 negative, 15 unsuccessful attempts). Intra-operatively, calprotectin was measured with lateral flow immunoassay test in these patients. Cases with calprotectin levels ≥ 50 mg/L were treated with 2-stage revision THA; otherwise, they were considered not-infected and one-stage revision was performed. Synovial fluid and tissue samples were collected for analysis. Implants were sent for sonication fluid cultures.Calprotectin was positive (≥ 50 mg/L) in 27 cases and negative in 21 cases. There was 1 false negative case with positive tissue cultures. Out of the 27 positive cases, 25 had positive tissue cultures and sonication. However, 2 cases with high calprotectin levels (&gt;200 mg/L) were not infected. The false positive result was attributed to severe metallosis. Calprotectin sensitivity was 96.2%, specificity 90.9%, PPV 92.6%, NPV 95.2%, AUC 0.935.The results of this ongoing study indicate that calprotectin seems to be a valuable tool in facilitating the intra-operative decision-making process in cases that low-grade infection is suspected and diagnosis cannot be established pre-operatively.

The value of sonication in the differential diagnosis of septic and aseptic femoral and tibial shaft nonunion in comparison to conventional tissue culture and histopathology: a prospective multicenter clinical study

BackgroundSeptic and aseptic nonunion require different therapeutic strategies. However, differential diagnosis is challenging, as low-grade infections and biofilm-bound bacteria often remain undetected. Therefore, the examination of biofilm on implants by sonication and the evaluation of its value for differentiating between femoral or tibial shaft septic and aseptic nonunion in comparison to tissue culture and histopathology was the focus of this study.Materials and methodsOsteosynthesis material for sonication and tissue samples for long-term culture and histopathologic examination from 53 patients with aseptic nonunion, 42 with septic nonunion and 32 with regular healed fractures were obtained during surgery. Sonication fluid was concentrated by membrane filtration and colony-forming units (CFU) were quantified after aerobic and anaerobic incubation. CFU cut-off values for differentiating between septic and aseptic nonunion or regular healers were determined by receiver operating characteristic analysis. The performances of the different diagnostic methods were calculated using cross-tabulation.ResultsThe cut-off value for differentiating between septic and aseptic nonunion was ≥ 13.6 CFU/10 ml sonication fluid. With a sensitivity of 52% and a specificity of 93%, the diagnostic performance of membrane filtration was lower than that of tissue culture (69%, 96%) but higher than that of histopathology (14%, 87%). Considering two criteria for infection diagnosis, the sensitivity was similar for one tissue culture with the same pathogen in broth-cultured sonication fluid and two positive tissue cultures (55%). The combination of tissue culture and membrane-filtrated sonication fluid had a sensitivity of 50%, which increased up to 62% when using a lower CFU cut-off determined from regular healers. Furthermore, membrane filtration demonstrated a significantly higher polymicrobial detection rate compared to tissue culture and sonication fluid broth culture.ConclusionsOur findings support a multimodal approach for the differential diagnosis of nonunion, with sonication demonstrating substantial usefulness.Level of Evidence: Level 2Trial registration DRKS00014657 (date of registration: 2018/04/26)

Age and CRP Associated With Improved Tissue Pathogen Identification in Children With Blood Culture Negative Osteomyelitis: Results From the CORTICES Multicenter Database.

Acute hematogenous osteomyelitis (AHO) is a relatively common condition in children, and identifying the offending pathogen with blood or tissue cultures aids in diagnosis and medical management while reducing treatment failure. Recent 2021 AHO clinical practice guidelines from the Pediatric Infectious Disease Society recommend obtaining routine tissue cultures, particularly in cases with negative blood cultures. The purpose of this study was to identify variables associated with positive tissue cultures when blood cultures are negative. Children with AHO from 18 pediatric medical centers throughout the United States through the Children's ORthopaedic Trauma and Infection Consortium for Evidence-based Study were evaluated for predictors of positive tissue cultures when blood cultures were negative. Cutoffs of predictors were determined with associated sensitivity and specificity. One thousand three children with AHO were included, and in 688/1003 (68.6%) patients, both blood cultures and tissue cultures were obtained. In patients with negative blood cultures (n=385), tissue was positive in 267/385 (69.4%). In multivariate analysis, age (P<0.001) and C-reactive protein (CRP) (P=0.004) were independent predictors. With age >3.1 years and CRP >4.1mg/dL as factors, the sensitivity of obtaining a positive tissue culture when blood cultures were negative was 87.3% (80.9-92.2%) compared with 7.1% (4.4-10.9%) if neither of these factors was present. There was a lower ratio of methicillin-resistant Staphylococcus aureus in blood culture-negative patients who had a positive tissue culture 48/188 (25.5%), compared with patients who had both positive blood and tissue cultures 108/220 (49.1%). AHO patients with CRP ≤ 4.1mg/dL and age under 3.1 years are unlikely to have clinical value from tissue biopsy that exceeds the morbidity associated with this intervention. In patients with CRP > 4.1mg/dL and age over 3.1 years, obtaining a tissue specimen may add value; however, it is important to note that effective empiric antibiotic coverage may limit the utility of positive tissue cultures in AHO. Level III-Retrospective comparative study.

The role of sonication in the diagnosis of periprosthetic joint infection in total shoulder arthroplasty

An increased sensitivity of sonication compared to periprosthetic tissue cultures in the diagnosis of periprosthetic joint infection (PJI) of hip and knee arthroplasty has been reported. The goal of this study was to determine if there is also an added value of implant sonication in the diagnosis of PJI in total shoulder arthroplasty (TSA). A retrospective analysis of patients who underwent removal of their TSA combined with sonication of the implant for suspicion of PJI between April 2009 and August 2017 was performed. The diagnosis of PJI was based on the major criteria described by Parvizi. We calculated sensitivity, specificity, predictive values, likelihood ratios and diagnostic accuracy for sonication cultures in comparison with periprosthetic tissue cultures. Data from 41 patients were analysed. Standard synovial fluid cultures combined with intraoperative periprosthetic tissue cultures had a sensitivity of 95%, specificity of 95% and total accu- racy of 95%. Sonication cultures had a sensitivity of 91%, specificity of 68% and total accuracy of 80%. Six patients had negative standard cultures but positive sonication cultures. In patients with only one positive standard culture, the pathogen of the sonication culture corresponded to the pathogen of the positive soft tissue culture. We found a possible added value of sonication of TSA in the diagnosis of PJI in conjunction with standard intraoperative cultures. In some patients with suspicion of low-grade TSA infection, sonication could identify a possible causal microorganism despite negative standard cultures.

Clinical Application of the Mycobacterium tuberculosis-RNA Assay of Pericardial Tissue Specimens in the Diagnosis of Tuberculous Pericarditis.

To assess the accuracy of the Mycobacterium tuberculosis (MTB)-RNA assay using pericardial tissue specimens for tuberculous pericarditis (TBP) diagnosis. MTB culture and MTB-RNA assay were performed for patients with suspected TBP. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and area under the curve (AUC) of these two assays were analyzed. This study included 79 patients. The sensitivity, specificity, PPV, NPV, and AUC were 28.1% (18/64), 100.0% (15/15), 100.0% (18/18), 24.6% (15/61), and 0.64 for the MTB culture and 37.5% (24/64), 100.0% (15/15), 100.0% (24/24), 27.3% (15/55), and 0.69 for the MTB-RNA assay, respectively. Patients with positive pericardial tissue culture were defined as having definite TBP; in other words, culture was the gold standard for this group of patients and had a sensitivity, specificity, PPV, and NPV of 100% and an AUC of 1.00. However, these values were found to be 72.2% (13/18), 100.0% (15/15), 100.0% (13/13), 75.0% (15/20), and 0.86 for the MTB-RNA assay, respectively. Among patients with probable TBP (culture-negative patients), the sensitivity, specificity, NPV, and AUC of MTB culture were 0.0% (0/46), 100.0% (15/15), 24.6% (15/61), and 0.50, respectively, but the PPV could not be determined. These values were found to be 23.9% (11/46), 100.0% (15/15), 100.0% (11/11), 30.0% (15/50), and 0.62 for the MTB-RNA assay, respectively. MTB-RNA assay using pericardial tissues had limited diagnostic efficacy for TBP. In culture-positive TBP, the diagnostic accuracy of MTB-RNA was good. In contrast, in culture-negative TBP, its diagnostic accuracy was unsatisfactory.

Microbial colonization of sacral nerve stimulators pseudo-capsule: A single institution experience.

To evaluate the incidence and type of microbial colonization of the pseudo-capsule (PC) that forms around sacral nerve stimulators (SNS) and consequently the significance of surgical excision of this PC at time of SNS revision or removal. A cohort of 31 patients who underwent SNS revision or removal from January 2018 to June 2021 were retrospectively reviewed. The baseline demographics, rate and type of PC microbial colonization and development of SNS insertion site infection were reported. A cohort of 31 patients who underwent "InterStim device (Medtronic)" revision or removal were included. The majority were females (93.5%). The most common indication for SNS insertion was refractory overactive bladder (67.7%). Nine patients (29.0%) underwent SNS revision due to malfunctional device, and 9 patients had SNS removal for the need of MRI procedures. Four patients (12.9%) had positive tissue culture growing Coryneform bacillus (50.0%), Cutibacterium acnes (25.0%) and Pseudomonas aeruginosa (25.0%). PC colonization was uncommon at the time of SNS explant. However, more research is needed to better understand the role of PC-positive culture in increasing the risk of SNS device infections if strict adherence to sterile techniques is adopted.