Treatment outcomes of patients with Cutibacterium acnes-positive cultures during total joint replacement revision surgery: a minimum 2-year follow-up.

INTRODUCTION: Periprosthetic joint infection (PJI) is a devastating complication following total joint replacement (TJR). Cutibacterium acnes (C. acnes) is a low virulent skin commensal, commonly found during TJR revision surgery for "aseptic" causes. The purpose of the present study was to report the treatment outcomes of patients with C. acnes contamination or infection in the presence of a TJR treated with a revision surgery ± implant exchange ± prolonged (≥ 8 weeks) postoperative antibiotics. METHODS: Medical records of patients with at least one positive C. acnes culture in intraoperative tissue samples or sonication fluid from a TJR revision surgery between January 2005 and December 2014 were retrospectively evaluated. The primary endpoint was infection eradication according to Delphi criteria. The diagnostic accuracy of preoperative TJR aspiration regarding the diagnosis of C. acnes PJI was also investigated. RESULTS: A total of 52 TJR (28 shoulders, 17 hips, 7 knees) in 52 patients (35 males, 17 females) with an average age of 63 ± 11 (33-86) years were included. At an average follow-up of 67 ± 33 (24-127) months, the infection eradication of C. acnes PJI was 97% regardless of the surgical treatment or administration of prolonged postoperative antibiotics. The incidence of unsuspected C. acnes PJI was 28.8%. The sensitivity and specificity of preoperative joint aspiration in detecting C. acnes PJI were 59% and 88%, whereas the PPV and NNV were 83% and 67%, respectively. CONCLUSION: Infection eradication of C. acnes PJI was very high at a minimum follow-up of 24 months, suggesting that C. acnes PJI could be adequately treated with a combination of revision surgery and prolonged postoperative antibiotics. The preoperative diagnosis of C. acnes PJI might be challenging with more than one-quarter of patients presenting without suspicion of C. acnes PJI. The appropriate treatment of patients with a single positive culture remains still unclear. A negative TJR aspiration should not rule out a C. acnes PJI, especially in the presence of clinical correlates of infection. LEVEL OF EVIDENCE: Retrospective case-control study, Level III. IRB APPROVAL: Kantonale Ethikkommission Zürich, BASEC Nr.:2017-00567.

Clostridioides difficile infection (CDI) epidemiology and patient characteristics in Switzerland.

OBJECTIVES: Clostridioides difficile infection (CDI) is a disease with high morbidity and mortality rates. The objective of this study was to describe CDI epidemiology and patient characteristics over a 5-year period in Switzerland and assess risk factors for mortality, recurrence and severe CDI. PATIENTS AND METHODS: We retrospectively included all consecutive CDI cases having occurred in adult patients hospitalized in two tertiary centers: the Lausanne University Hospital (1000 beds) and the University Hospital of Zurich (900 beds), between 2014 and 2018. Suspected cases of CDI were identified from the microbiology laboratory database on the basis of a positive test and confirmed by records review. RESULTS: During first CDI episodes, the median age was 67 years and the median Charlson comorbidity index (CCI) score was 5. All in all, 299 out of 826 patients (36.2%) had severe infection based on the Infectious Diseases Society of America criteria. In the multivariable analysis, CCI was associated with increased risk of mortality. None of the factors recorded on admission were significantly associated with increased risk of recurrence. In the multivariable analysis, male sex and CCI were associated with severity, while immunosuppression was associated with less severe presentation. CONCLUSIONS: If we did not identify any criteria on admission that could be predictive of recurrences, this could be explained the retrospective nature of the study. A higher comorbidity index is a key driver for severe CDI and mortality. Reporting of CDI is not mandatory in Switzerland; structuration of CDI reporting should be a short-term priority.

Diagnostic accuracy of 99mTc-antigranulocyte SPECT/CT in patients with osteomyelitis and orthopaedic device-related infections: A retrospective analysis.

OBJECTIVES: Conventional imaging techniques are routinely used in the diagnostic work-up of patients with suspected osteomyelitis or orthopaedic implant-associated infections. Hybrid nuclear medicine imaging techniques are a suitable alternative to routine imaging modalities as they provide anatomical and functional information within one procedure. Our study investigated the performance of anti-granulocyte SPECT/CT using 99mTc-labelled monoclonal antibodies in the diagnosis of osteomyelitis and orthopaedic implant-associated infections. METHODS: In this retrospective analysis, we included patients with 99mTc-antigranulocyte SPECT/CT acquired in the context of a suspected bone and joint infection. All patients underwent routine diagnostics and/or had a clinical follow-up of at least 12months. RESULTS: 26 episodes were included. Fifteen exams were performed for suspected osteomyelitis, and 11 for suspected orthopaedic implant-associated infection. SPECT/CT was ordered most often if standard diagnostic tests or conventional imaging modalities remained inconclusive. The overall sensitivity and specificity for the diagnosis of an infection were 77.8% and 94.1%, respectively. The positive predictive value was 87.5% and the negative predictive value 88.9%. Diagnostic accuracy was 88.5%. CONCLUSIONS: 99mTc-antigranulocyte SPECT/CT imaging has a high accuracy in the diagnosis of osteomyelitis and orthopaedic implant-associated infections and is a suitable non-invasive diagnostic tool if standard diagnostic examinations are inconclusive or not applicable.

Synovial C-reactive protein features high negative predictive value but is not useful as a single diagnostic parameter in suspected periprosthetic joint infection (PJI).

OBJECTIVES: Synovial fluid C-reactive protein (syCRP) has been recently described as a new biomarker in preoperative diagnostics to identify periprosthetic joint infections (PJI). The aim of this study was to evaluate syCRP in a large cohort of patients with suspected PJI and to calculate the optimal cut-off to diagnose PJI. METHODS: Between September 2015 and June 2017, we prospectively included patients with suspected PJI, in which syCRP was additionally measured along with routine preoperative diagnostic serum and synovial biomarkers. We analysed the sensitivity and specificity of syCRP using receiver operating characteristic curves. RESULTS: We included 192 cases (hip n = 80, knee n = 91, shoulder n = 21) with a final diagnosis of PJI in 26 cases (14.0%). Combined for all joints, the syCRP values were significantly higher in the PJI group than in the no PJI group (median: 13.8 vs. 0 mg/l; p < 0.001). The optimal cut-off (Youden Index: 0.71) for the PJI diagnosis combined for all joints was at a syCRP value of 2.9 mg/l with a sensitivity of 88%, a specificity of 82%, and a negative predictive value of 98%. CONCLUSIONS: SyCRP features high negative predictive value but is not useful as a single diagnostic parameter in suspected periprosthetic joint infection (PJI).

Inflammatory disorders mimicking periprosthetic joint infections may result in false-positive α-defensin.

OBJECTIVES: The antimicrobial peptide α-defensin has recently been introduced as a potential 'single' biomarker with a high sensitivity and specificity for the preoperative diagnosis of periprosthetic joint infections (PJIs). However, most studies assessed the benefits of the test with exclusion of patients with rheumatic diseases. We aimed to evaluate the α-defensin test in a cohort study without exclusion of people with inflammatory diseases. METHODS: Between June 2016 and June 2017, we prospectively included cases with a suspected PJI and an available lateral flow test α-defensin (Synovasure®) in synovial fluid. We compared the test result to the diagnostic criteria for PJIs published by an International Consensus Group in 2013. RESULTS: We included 109 cases (49 hips, 60 knees) in which preoperative α-defensin tests had been performed. Among these, 20 PJIs (16 hips, four knees) were diagnosed. Preoperative α-defensin tests were positive in 25 cases (22.9%) with a test sensitivity and specificity of 90% and 92.1% (95% CI 68.3%-98.8% and 84.5%-96.8%, respectively), and a high negative predictive value of 97.6% (95% CI 91.7%-99.4%). We interpreted seven α-defensin tests as false positive, mainly in cases with inflammatory rheumatic diseases, including crystal deposition diseases. CONCLUSIONS: A negative synovial α-defensin test can reliably rule out a PJI. However, the test can be false positive in conjunction with an underlying non-infectious inflammatory disease. We therefore propose to use the α-defensin test only in combination with Musculoskeletal Infection Society criteria and assessment for crystals in synovial aspirates.

Characteristics and treatment outcomes of 69 cases with early prosthetic joint infections of the hip and knee.

PURPOSE: Early prosthetic joint infection (PJI) can be treated with an intensive surgical debridement and implant retention (DAIR) of the prosthesis if (1) the prosthesis is stable, (2) the pathogen is not a difficult-to-treat microorganism, (3) symptoms have lasted for <3 weeks and (4) a sinus tract is absent. METHODS: We retrospectively evaluated the treatment outcome of early PJI in the hip and knee in a single orthopaedic centre. An early PJI was defined as a prosthesis infection within 3 months after primary implantation or revision surgery for a non-infectious cause. RESULTS: We identified 69 patients with confirmed early PJI, with a median age of 71 (range 33-84) years. Only 64 % presented with ≥2 acute signs of infection. The most commonly isolated bacteria were coagulase-negative staphylococci (38 %) and Staphylococcus aureus (25 %). Surgical procedures included DAIR (50 cases, 69 %) and two-stage exchange (19 cases, 31 %). At last follow-up, five of remaining living 67 patients (7.5 %) had a relapse of infection. The overall relapse-free survival of the prosthesis after 2 years was 92.3 % (95 % confidence interval 82-97 %) with no significant difference between DAIR and exchange of prosthesis. CONCLUSION: Our data suggest that an early PJI should be treated with DAIR as a less invasive procedure whenever possible according to the established treatment algorithm.

Nodular secondary syphilis in a woman.

We report the case of a 21-year-old woman with symmetrically distributed, ulcerated nodules and plaques on the face, neck and arms. Initial differential diagnoses included pyoderma or sarcoidosis based on the clinical presentation and histopathology with non-caseating granulomas. After inefficient treatment with topical and systemic fusidic acid and steroids, we diagnosed nodular secondary syphilis owing to positive serology and immunohistochemical staining of Treponema pallidum in lesional skin. After treatment with benzathine penicillin, skin lesions improved and antibody titres declined significantly within 3 months. Nodular skin lesions in secondary syphilis are rare with 15 reported cases within the last 20 years. Furthermore, the granulomatous histology is often misleading. Our patient's case suggests that the physicians should be aware of syphilis as a possible differential diagnosis also in patients outside a high-risk population for sexually transmitted diseases and with an unusual clinical presentation.

Factors associated with rifampin resistance in staphylococcal periprosthetic joint infections (PJI): a matched case-control study.

PURPOSE: Rifampin combination therapy plays an important role in the management of staphylococcal periprosthetic joint infection (PJI). However, the emergence of rifampin resistance is a feared complication. We retrospectively analysed predetermined potential risk factors in patients with rifampin-resistant staphylococcal PJI in a multicentre case-control study. METHODS: Cases (n = 48) were defined as PJI caused by rifampin-resistant staphylococci. Rifampin-susceptible controls (n = 48) were matched for microorganism and type of prosthetic joint. Uni- and multivariable conditional logistic regression analyses were performed to estimate odds ratios (OR) with 95 % confidence intervals (95 % CI). RESULTS: Forty-eight cases (31 men; median age 67 years; age range 39-88 years) with hip- (n = 29), knee- (n = 13), elbow- (n = 4), shoulder- (n = 1) or ankle-PJI (n = 1) were enrolled in the study. Staphylococcus aureus and coagulase-negative staphylococci were isolated in ten and 38 episodes, respectively. Most of the cases (n = 44, 92 %) had a previous PJI, and 93 % (n = 41) of these had been treated with rifampin. There was an independent association of emergence of rifampin resistance with male sex (OR 3.6, 95 % CI 1.2-11), ≥ 3 previous surgical revisions (OR 4.7, 95 % CI 1.6-14.2), PJI treatment with high initial bacterial load (inadequate surgical debridement, <2 weeks of intravenous treatment of the combination medication; OR 4.9, 95 % CI 1.6-15) and inadequate rifampin therapy (OR 5.4, 95 % CI 1.2-25). CONCLUSIONS: Based on our results, extensive surgical debridement and adequate antibiotic therapy are needed to prevent the emergence of rifampin resistance.

Characteristics and outcome of 16 periprosthetic shoulder joint infections.

PURPOSE: Shoulder arthroplasties are increasingly performed, but data on periprosthetic joint infections (PJI) in this anatomical position are limited. We retrospectively investigated the characteristics and outcome of shoulder PJI after primary arthroplasty from 1998 to 2010 in a single centre. METHODS: Periprosthetic joint infection was defined as periprosthetic purulence, presence of sinus tract or microbial growth. A Kaplan-Meier survival method was used to estimate relapse-free survival of prosthesis. RESULTS: From 1,571 primary shoulder prostheses, we evaluated 16 patients with a PJI at different stages, i.e, early (n = 4), delayed (n = 6) and late (n = 6) infections. The median patient age was 67 (range 53-86) years, and 69 % were females. The most commonly isolated microorganism was Propionibacterium acnes in 38 % of patients (monobacterial in four and polymicrobial in two patients). In 14 of the 16 patients, surgical interventions consisting of debridement and implant retention (6 patients), exchange (7) and explantation (1) were performed. Four patients had a relapse of infection with P. acnes (n = 3) or Bacteroides fragilis (n = 1). The relapse-free survival of the prosthesis was 75 % (95 % confidence interval 46-90 %) after 1 and 2 years, 100 % in six patients following the treatment algorithm for hip and knee PJI and 60 % in 10 patients not followed up. All but one of the relapses were previously treated without exchange of the prosthesis. CONCLUSIONS: As recommended for hip and knee PJI, we suggest treating shoulder PJI with a low-grade infection by microorganisms such as P. acnes with an exchange of the prosthesis. Cohort studies are needed to verify our results.

Multicentric Castleman's disease as a cause for unclear febrile episodes in a 55-year-old HIV-infected man.

Our case illustrates the difficulties involved in diagnosing multicentric Castleman's disease (MCD) in a human immunodeficiency virus-infected man with febrile episodes and malaise. In the absence of well-established treatment protocols, we have chosen a new treatment algorithm with rituximab, etoposide, and valganciclovir, which led to the remission of clinical symptoms. Yet, we advocate focused exploration for MCD in immunosuppressed patients with unclear febrile episodes, as recent advances in treatment are promising.

Group B streptococcus in prosthetic hip and knee joint-associated infections.

The incidence of invasive group B streptococcus (GBS) infections in non-pregnant adults is increasing. Little is known about GBS in periprosthetic joint infections (PJIs). We aimed to analyse the clinical presentation of GBS PJI and its treatment in association with the outcome. The characteristics of 36 GBS PJIs collected from 10 centres were investigated. In 34 episodes, follow-up examination of ≥ 2 years was available, allowing treatment and outcome analysis. Most infections (75%) occurred ≥ 3 months after implantation. Most patients (91%) had at least one comorbidity; 69% presented with acute symptoms and 83% with damaged periprosthetic soft tissue. In 20 of 34 episodes debridement and retention of implant was attempted, but in five of these the prosthesis was ultimately removed. Hence, in 19 (56%) episodes, the implant was removed, including 14 immediate removals. In four episodes the removal was permanent. Penicillin derivatives and clindamycin were the most common antimicrobials administered (68%). In 94% the infection was cured, and in 82% functional mobility preserved. Debridement with implant retention was successful if the duration of symptoms was short, the prosthesis stable, and the tissue damage minor (10/10 vs 3/10 episodes, P = 0.003). Surgery that complied with a published algorithm was associated with a favourable outcome (P = 0.049).

Characteristics and outcome of 27 elbow periprosthetic joint infections: results from a 14-year cohort study of 358 elbow prostheses.

Elbow arthroplasty is increasingly performed in patients with rheumatic and post-traumatic arthritis. Data on elbow periprosthetic joint infection (PJI) are limited. We investigated the characteristics and outcome of elbow PJI in a 14-year cohort of total elbow arthroplasties in a single centre. Elbow prosthesis, which were implanted between 1994 and 2007 at Schulthess Clinic in Zurich, were retrospectively screened for infection. PJI was defined as periprosthetic purulence, the presence of sinus tract or microbial growth. A Kaplan-Meier survival method and Cox proportional hazard analysis were performed. Of 358 elbow prostheses, PJI was identified in 27 (7.5%). The median patient age (range) was 61 (39-82) years; 63% were females. Seventeen patients (63%) had a rheumatic disorder and ten (37%) had osteoarthritis. Debridement and implant retention was performed in 78%, followed by exchange or removal of the prosthesis (15%) or no surgery (7%).The relapse-free survival (95% CI) was 79% (63-95%) after 1 year and 65% (45-85%) after 2 years. The outcome after 2 years was significantly better when patients were treated according to the algorithm compared to patients who were not (100% vs. 33%, p <0.05). In 21 patients treated with debridement and retention, the cure rate was also higher when the algorithm was followed (100% vs. 11%, p <0.05). The findings of the present study suggest that the treatment algorithm developed for hip and knee PJI can be applied to elbow PJI. With proper patient selection and antimicrobial therapy, debridement and retention of the elbow prosthesis is associated with good treatment outcome.