Incidence of Acute Kidney Injury Among Critically Ill Patients With Brief Empiric Use of Antipseudomonal ß-Lactams With Vancomycin.

BACKGROUND: Nephrotoxins contribute to 20%-40% of acute kidney injury (AKI) cases in the intensive care unit (ICU). The combination of piperacillin-tazobactam (PTZ) and vancomycin (VAN) has been identified as nephrotoxic, but existing studies focus on extended durations of therapy rather than the brief empiric courses often used in the ICU. The current study was performed to compare the risk of AKI with a short course of PTZ/VAN to with the risk associated with other antipseudomonal ß-lactam/VAN combinations. METHODS: The study included a retrospective cohort of 3299 ICU patients who received ≥24 but ≤72 hours of an antipseudomonal ß-lactam/VAN combination: PTZ/VAN, cefepime (CEF)/VAN, or meropenem (MER)/VAN. The risk of developing stage 2 or 3 AKI was compared between antibiotic groups with multivariable logistic regression adjusted for relevant confounders. We also compared the risk of persistent kidney dysfunction, dialysis dependence, or death at 60 days between groups. RESULTS: The overall incidence of stage 2 or 3 AKI was 9%. Brief exposure to PTZ/VAN did not confer a greater risk of stage 2 or 3 AKI after adjustment for relevant confounders (adjusted odds ratio [95% confidence interval] for PTZ/VAN vs CEF/VAN, 1.11 [.85-1.45]; PTZ/VAN vs MER/VAN, 1.04 [.71-1.42]). No significant differences were noted between groups at 60-day follow-up in the outcomes of persistent kidney dysfunction (P = .08), new dialysis dependence (P = .15), or death (P = .09). CONCLUSION: Short courses of PTZ/VAN were not associated with a greater risk of short- or 60-day adverse renal outcomes than other empiric broad-spectrum combinations.

Sonication Culture of Antimicrobial Agent-Containing Cement Spacers Removed during Staged Revisions for Arthroplasty Infection.

Diagnosis of persistent infection at the time of reimplantation for staged revision of infected arthroplasties is challenging. Implant sonication culture for the diagnosis of prosthetic joint infection (PJI) has improved sensitivity compared to standard periprosthetic tissue culture. We report our experience with periprosthetic tissue culture and sonication culture of antimicrobial agent-containing cement spacers (ACSs) collected during second stages of staged revisions for arthroplasty infection. We studied 87 ACSs from 66 patients undergoing two-stage revision arthroplasty for PJI submitted for sonication culture, along with conventional periprosthetic tissue cultures. Two or more positive periprosthetic tissue cultures with the same organism were considered a positive tissue culture. For sonication culture, ≥20 CFU of bacteria per 10 ml of sonicate fluid was considered positive. The sensitivity and specificity of periprosthetic tissue and ACS sonication culture in detecting persistent infection, as well as their association with outcome, were assessed. Persistent infection occurred in 26% of cases. Periprosthetic tissue and sonicate fluid culture had specificities of 96.3 and 100% (P = 0.50), respectively, and sensitivities of 31.6 and 26.3% (P = 1.00), respectively, for the diagnosis of persistent infection. Thirteen subjects deemed not to have persistent infection at time of reimplantation and who had negative periprosthetic tissue and sonicate fluid cultures subsequently developed overt infection. Sonication culture of cement spacers identifies a similar proportion of patients with persistent infection during staged revisions, as detected by periprosthetic tissue cultures; both have low sensitivities to detect persistent infection.

Diagnostic evaluation and management of culture-negative cardiovascular implantable electronic device infections.

BACKGROUND: Culture-negative (CN) cardiovascular implantable electronic device (CIED) infections represent a significant management challenge for clinicians with no specific guidelines addressing this subgroup of patients. The aim of the current investigation is to report our institutional experience of CN CIED infections and propose a systematic approach to diagnostic evaluation and management of these complicated cases based on our observations. METHODS: We retrospectively screened all CIED infection cases at Mayo Clinic from 2005 through 2017. Using standardized criteria to define significant microbial growth, all patients with positive blood or pocket/device cultures were excluded. RESULTS: A total of 835 cases of CIED infection were screened, and of these, 47 (6%) met CN-CIED infection criteria. Majority of patients (77%) in this cohort had received antimicrobial therapy prior to device cultures with a median duration of 8 days. The most common presentation was device pocket infection (81%). All patients underwent device removal. Route of antibiotics was switched from oral to parenteral and spectrum of activity expanded from initial therapy in 23% of patients despite negative cultures. Majority of patients (80%) were dismissed on parenteral therapy. Adverse events attributed to intravenous antibiotic therapy were documented in 63% of the cases. No recurrence was reported and 6-month survival was 94.8%. CONCLUSIONS: Pocket and device cultures in suspected CIED infections may be negative due to preextraction oral antibiotics. However, frequently these patients are managed with broad-spectrum parenteral therapy postextraction.

Outcomes in Patients With Cardiovascular Implantable Electronic Device Infection Managed With Chronic Antibiotic Suppression.

BACKGROUND.: Most cardiovascular implantable electronic device (CIED) recipients are elderly, have multiple comorbid conditions, and are at increased risk of CIED infection (CIEDI). Current guidelines recommend complete device removal in patients with CIEDI to prevent relapse and mortality. However, comorbidities or other factors may preclude device removal, thus prompting a nonsurgical approach that includes chronic antibiotic suppression (CAS). There are limited data on outcomes of patients receiving CAS for CIEDI. METHODS.: We retrospectively screened 660 CIEDI cases from 2005 to 2015 using electronic health records and a CIEDI institutional database and identified 48 patients prescribed CAS. Primary outcomes were infection relapse and survival. RESULTS.: The median age was 78 years, and 73% (35/48) were male. The median Charlson comorbidity index was 4. Common pathogens were coagulase-negative staphylococci (21%, 10/48) and methicillin-sensitive Staphylococcus aureus (19%, 9/48). At 1 month after hospitalization, 25% (12/48) of patients had died, of whom only 1 initiated CAS; 67% (8/12) of these had staphylococcal infections. Of the 37 patients who initiated CAS, the most common antimicrobials were trimethoprim-sulfamethoxazole, penicillin, and amoxicillin (22%, 8/37 each). Estimated median overall survival was 1.43 years (95% confidence interval, 0.27-2.14), with 18% (6/33 survivors) developing relapse within 1 year. Of the 6 patients who relapsed, 2 (33%) subsequently underwent CIED extraction. CONCLUSION.: CAS is reasonable in select patients who are not candidates for complete device removal for attempted cure of CIEDI. Nevertheless, 1-month mortality in our sample of CAS-eligible patients was high and reflective of high rates of comorbid conditions.

A Novel Prosthetic Joint Infection Pathogen, Mycoplasma salivarium, Identified by Metagenomic Shotgun Sequencing.

Defining the microbial etiology of culture-negative prosthetic joint infection (PJI) can be challenging. Metagenomic shotgun sequencing is a new tool to identify organisms undetected by conventional methods. We present a case where metagenomics was used to identify Mycoplasma salivarium as a novel PJI pathogen in a patient with hypogammaglobulinemia.

Utility of Brain Magnetic Resonance Imaging in the Surgical Management of Infective Endocarditis.

BACKGROUND: Brain magnetic resonance imaging (MRI) is frequently obtained in patients with infective endocarditis, yet its utility in predicting outcomes for valve replacement surgery in patients is unknown. The objective of this study was to determine how brain MRI findings impact clinical management and outcomes. METHODS: Demographic and clinical data from electronic medical records at Mayo Clinic were retrospectively reviewed for patients hospitalized with definite or possible infective endocarditis according to the modified Duke criteria between January 1, 2007 and December 31, 2014. There were 364 patients included in the study. RESULTS: Cardiac valve replacement surgery was performed in 195 of 364 (53.6%) patients, and 95 (48.7%) of the surgical patients underwent preoperative MRI, which was associated with preoperative neurologic symptoms in 56 of 95 (58.9%) patients (odds ratio = 12.92; 95% confidence interval, 5.98-27.93; P <.001). Postoperative neurologic complications occurred in 24 of 195 (12.3%) patients, including new ischemic stroke in 4 of 195 (2.1%) and new intracerebral hemorrhage in 3 of 195 (1.5%). No patients with microhemorrhages developed postoperative hemorrhage. No significant differences existed in rates of postoperative complications between patients with and those without preoperative MRI. There were no substantial associations between preoperative MRI findings and postoperative neurologic complications, functional outcomes as described by the modified Rankin Scale score, or 6-month mortality. CONCLUSIONS: In patients undergoing valve replacement surgery, preoperative MRI findings were not associated with differences in postoperative outcomes, irrespective of finding or timing of valve replacement surgery.

Infective Endocarditis in Adults: Diagnosis, Antimicrobial Therapy, and Management of Complications: A Scientific Statement for Healthcare Professionals From the American Heart Association.

BACKGROUND: Infective endocarditis is a potentially lethal disease that has undergone major changes in both host and pathogen. The epidemiology of infective endocarditis has become more complex with today's myriad healthcare-associated factors that predispose to infection. Moreover, changes in pathogen prevalence, in particular a more common staphylococcal origin, have affected outcomes, which have not improved despite medical and surgical advances. METHODS AND RESULTS: This statement updates the 2005 iteration, both of which were developed by the American Heart Association under the auspices of the Committee on Rheumatic Fever, Endocarditis, and Kawasaki Disease, Council on Cardiovascular Disease of the Young. It includes an evidence-based system for diagnostic and treatment recommendations used by the American College of Cardiology and the American Heart Association for treatment recommendations. CONCLUSIONS: Infective endocarditis is a complex disease, and patients with this disease generally require management by a team of physicians and allied health providers with a variety of areas of expertise. The recommendations provided in this document are intended to assist in the management of this uncommon but potentially deadly infection. The clinical variability and complexity in infective endocarditis, however, dictate that these recommendations be used to support and not supplant decisions in individual patient management.

Cardiovascular Implantable Electronic Device Infections due to Propionibacterium Species.

INTRODUCTION: Propionibacterium species are part of the normal skin flora and often considered contaminants when identified in cultures. However, they can cause life-threatening infections, including prosthetic cardiovascular device infections. Clinical presentation and management of cardiovascular implantable electronic device (CIED) infection due to Propionibacterium species has not been well described. METHODS: Retrospective review of all cases of CIED infection due to Propionibacterium species admitted to Mayo Clinic between January 1, 1990 and December 31, 2014. Patient charts were reviewed for clinical, microbiological, and imaging data. Descriptive analysis was performed. RESULTS: We identified 14 patients with CIED infection due to Propionibacterium species, accounting for 2.3% of all CIED infections. Patients were predominantly male (n = 12, 86%). The median age at admission was 58.5 years (range 22-83). Twelve patients had implantable cardioverter defibrillators (ICDs) and two had permanent pacemaker systems. Twelve patients had generator pocket infection (86%). Two patients met clinical criteria for CIED-related infective endocarditis. Median time between last device manipulation and infection was 9 months (range 1-98). All patients were treated with complete device removal and antibiotic therapy. Six-month follow-up data were available for 10 patients (71%), with no relapses documented. CONCLUSION: CIED infections due to Propionibacterium species accounted for 2.3% of all device infections over a 25-year period. The most common infectious syndrome was generator pocket infection with delayed onset. There was an unanticipated predominance of ICDs in this cohort. Cure was achieved in all cases with complete device removal and antibiotic therapy.

Randomized Trial of Rapid Multiplex Polymerase Chain Reaction-Based Blood Culture Identification and Susceptibility Testing.

BACKGROUND: The value of rapid, panel-based molecular diagnostics for positive blood culture bottles (BCBs) has not been rigorously assessed. We performed a prospective randomized controlled trial evaluating outcomes associated with rapid multiplex PCR (rmPCR) detection of bacteria, fungi, and resistance genes directly from positive BCBs. METHODS: A total of 617 patients with positive BCBs underwent stratified randomization into 3 arms: standard BCB processing (control, n = 207), rmPCR reported with templated comments (rmPCR, n = 198), or rmPCR reported with templated comments and real-time audit and feedback of antimicrobial orders by an antimicrobial stewardship team (rmPCR/AS, n = 212). The primary outcome was antimicrobial therapy duration. Secondary outcomes were time to antimicrobial de-escalation or escalation, length of stay (LOS), mortality, and cost. RESULTS: Time from BCB Gram stain to microorganism identification was shorter in the intervention group (1.3 hours) vs control (22.3 hours) (P < .001). Compared to the control group, both intervention groups had decreased broad-spectrum piperacillin-tazobactam (control 56 hours, rmPCR 44 hours, rmPCR/AS 45 hours; P = .01) and increased narrow-spectrum ß-lactam (control 42 hours, rmPCR 71 hours, rmPCR/AS 85 hours; P = .04) use, and less treatment of contaminants (control 25%, rmPCR 11%, rmPCR/AS 8%; P = .015). Time from Gram stain to appropriate antimicrobial de-escalation or escalation was shortest in the rmPCR/AS group (de-escalation: rmPCR/AS 21 hours, control 34 hours, rmPCR 38 hours, P < .001; escalation: rmPCR/AS 5 hours, control 24 hours, rmPCR 6 hours, P = .04). Groups did not differ in mortality, LOS, or cost. CONCLUSIONS: rmPCR reported with templated comments reduced treatment of contaminants and use of broad-spectrum antimicrobials. Addition of antimicrobial stewardship enhanced antimicrobial de-escalation. CLINICAL TRIALS REGISTRATION: NCT01898208.

Predicting Risk of Endocarditis Using a Clinical Tool (PREDICT): Scoring System to Guide Use of Echocardiography in the Management of Staphylococcus aureus Bacteremia.

BACKGROUND: Infective endocarditis (IE) is a serious complication of Staphylococcus aureus bacteremia (SAB). There is limited clinical evidence to guide use of echocardiography in the management of SAB cases. METHODS: Baseline and 12-week follow-up data of all adults hospitalized at our institution with SAB from 2006 to 2011 were reviewed. Clinical predictors of IE were identified using multivariable logistic regression analysis. RESULTS: Of the 757 patients screened, 678 individuals with SAB (24% community acquired, 56% healthcare associated, and 20% nosocomial) met study criteria. Eighty-five patients (13%) were diagnosed with definite IE within the 12 weeks of initial presentation based on modified Duke criteria. The proportion of patients with IE was 22% (36/166) in community-acquired SAB, 11% (40/378) in community-onset healthcare-associated SAB, and 7% (9/136) in nosocomial SAB. Community-acquired SAB, presence of cardiac device, and prolonged bacteremia (≥ 72 hours) were identified as independent predictors of IE in multivariable analysis. Two scoring systems, day 1 (SAB diagnosis day) and day 5 (when day 3 culture results are known), were derived based on the presence of these risk factors, weighted in magnitude by the corresponding regression coefficients. A score of ≥ 4 for day 1 model had a specificity of 96% and sensitivity of 21%, whereas a score of <2 for day 5 model had a sensitivity of 98.8% and negative predictive value of 98.5%. CONCLUSIONS: We propose 2 novel scoring systems to guide use of echocardiography in SAB cases. Larger prospective studies are needed to validate the classification performance of these scoring systems.

Association of Mitral Valve Prolapse With Infective Endocarditis Due to Viridans Group Streptococci.

Although patients with certain cardiac valve abnormalities have increased risk of infective endocarditis (IE), it is unknown whether these abnormalities are associated with specific pathogens in IE cases. We report a strong association between mitral valve prolapse and viridans group streptococcal IE in a population-based cohort from Olmsted County, Minnesota.

Novel Bone-Targeting Agent for Enhanced Delivery of Vancomycin to Bone.

We examined the pharmacokinetic properties of vancomycin conjugated to a bone-targeting agent (BT) with high affinity for hydroxyapatite after systemic intravenous administration. The results confirm enhanced persistence of BT-vancomycin in plasma and enhanced accumulation in bone relative to vancomycin. This suggests that BT-vancomycin may be a potential carrier for the systemic targeted delivery of vancomycin in the treatment of bone infections, potentially reducing the reliance on surgical debridement to achieve the desired therapeutic outcome.

Temporal trends in infective endocarditis epidemiology from 2007 to 2013 in Olmsted County, MN.

BACKGROUND: The aim of this study is to determine if there have been contemporary shifts in infective endocarditis (IE) epidemiology in our local population; an analysis of cases from 2007 to 2013 was conducted. METHODS: This is a population-based review of all adults (≥18 years) residing in Olmsted County, MN, with definite or possible IE using the Rochester Epidemiology Project from January 1, 2007, to December 31, 2013. RESULTS: We identified 51 cases of IE in Olmsted County, MN, between 2007 and 2013. Median age of IE cases was 68.8 years (interquartile range 55.6-76.5), and 41% were females. Age- and sex-adjusted incidence of IE was 7.4 (95% CI 5.3-9.4) cases per 100,000 person-years. From a multivariable Poisson regression model, incidence of IE did not change significantly during the study period (P = .222) but was significantly higher in males and those of older age (P < .001). The annual incidences (per 100,000 person-years) were 2.5 for Staphylococcus aureus, 1.1 for viridans group streptococci, 1.6 for Enterococcus species, and 0.8 for coagulase-negative staphylococci. Only 19.6% (10/51) of Olmsted County patients underwent valve surgery between 2007 and 2013 as compared with 44.4% (197/444) of non-Olmsted County patients treated at Mayo Clinic Rochester. CONCLUSION: In this population-based study, no significant change in the overall incidence of IE in Olmsted County, MN, between 2007 and 2013 was seen, and it was similar to that seen between 1970 and 2006. Male gender and older age were associated with increased IE risk. With a lesser extent of cases attributable to viridans group streptococcal IE compared with previous years, S aureus was the predominant pathogen in IE cases during 2007 to 2013. The relatively low valve surgery rate was disparate from that reported from large, tertiary care centers (including our own) with non-population-based cohorts, which are subject to referral bias and can influence the expected characterization of IE.

Do claims-based comorbidities adequately capture case mix for surgical site infections?

BACKGROUND: There is increasing interest in using administrative claims data for surveillance of surgical site infections in THAs and TKAs, but the performance of claims-based models for case-mix adjustment has not been well studied. Performance of claims-based models can be improved with the addition of clinical risk factors for surgical site infections. QUESTIONS/PURPOSES: We assessed (1) discrimination and calibration of claims-based risk-adjustment models for surgical site infections; and (2) the incremental value of adding clinical risk factors to claims-based risk-adjustment models for surgical site infections. PATIENTS AND METHODS: Our study included all THAs and TKAs performed at a large tertiary care hospital from January 1, 2002 to December 31, 2009 (total n = 20,171 procedures). Revision procedures for infections were excluded. Comorbidity data were ascertained through administrative records and classified by the Charlson comorbidity index. Clinical details were obtained from the institutional joint registry and patients' electronic health records. Cox proportional hazards regression models were used to estimate the 1-year risk of surgical site infections with a robust sandwich covariance estimator to account for within-subject correlation of individuals with multiple surgeries. The performance of claims-based risk models with and without the inclusion of four clinical risk factors (morbid obesity, prior nonarthroplasties on the same joint, American Society of Anesthesiologists score, operative time) was assessed using measures of discrimination (C statistic, Somers' D xy rank correlation, and the Nagelkerke R(2) index). Furthermore, calibrations of claims-based risk models with and without clinical factors were assessed graphically by plotting the smoothed trends between model predictions and empirical rates from Kaplan-Meier. RESULTS: Discrimination of the claims-based risk models was moderate for the THA (C statistic = 0.662, D xy = 0.325, R(2) = 0.028) and TKA (C statistic = 0.621, D xy = 0.241, R(2) = 0.017) cohorts. Inclusion of four clinical risk factors improved discrimination in both cohorts with significant improvement in the C statistic in the THA cohort (C statistic = 0.043; 95% CI, 0.012-0.074) and in the TKA cohort (C statistic = 0.027; 95% CI, 0.007-0.047). Visual inspection suggested that calibration of the claims-based risk models was adequate and comparable to that of models which included the four additional clinical factors. CONCLUSIONS: Claims-based risk-adjustment models for surgical site infections in THA and TKA appear to be adequately calibrated but lack predictive discrimination, particularly with TKAs. The addition of clinical risk factors improves the discriminative ability of the models to a moderate degree; however, addition of clinical factors did not change calibrations, as the models showed reasonable degrees of calibration. When used in the clinical setting, the predictive performance of claims-based risk-adjustment models may be improved further with inclusion of additional clinical data elements.

Clinical presentation and outcomes of cardiovascular implantable electronic device infections in hemodialysis patients.

BACKGROUND: Infection is a serious complication of cardiovascular implantable electronic device (CIED) implantation. Kidney failure is as an independent risk factor for CIED infection and associated mortality. The presence of multiple comorbid conditions may contribute to varied clinical presentations and poor outcomes in hemodialysis (HD)-dependent patients with cardiac device infection. STUDY DESIGN: Case series. SETTING & PARTICIPANTS: CIED infections in HD patients (n=17) and non-HD patients (n=398) at Mayo Clinic in Rochester, MN, between 1991 and 2008. OUTCOMES: Surgical management and death. MEASUREMENTS: Clinical presentations, microbial organisms. RESULTS: Of 415 patients admitted with CIED infection, 17 (4%) were receiving maintenance HD therapy. Among those on HD therapy, mean age was 72±15 (SD) years, 59% were women, and 53% had a central venous catheter for dialysis access. All 17 patients receiving HD therapy presented with CIED-associated bloodstream infection and 41% of these had infected vegetations on CIED leads or cardiac valves. A majority (82%) were managed with complete device removal and almost half (43%) received a replacement device when bloodstream infection cleared. Device infection was associated with significant short-term mortality in HD patients and 90-day survival was only 76% in this group of patients. LIMITATIONS: Smaller sample size, majority white cohort, observational study. CONCLUSIONS: CIED infection in patients receiving HD usually is associated with bloodstream infection and frequently is complicated with device-related endocarditis. Despite complete device removal in the majority of HD patients with infection, mortality remains high.

Incidence of infective endocarditis caused by viridans group streptococci before and after publication of the 2007 American Heart Association's endocarditis prevention guidelines.

BACKGROUND: The American Heart Association published updated guidelines for infective endocarditis (IE) prevention in 2007 that markedly restricted the use of antibiotic prophylaxis in certain at-risk patients undergoing dental and other invasive procedures. The incidence of IE caused by viridans group streptococci (VGS) in the United States after publication of the 2007 American Heart Association guidelines has not been reported. METHODS AND RESULTS: We performed a population-based review of all definite or possible cases of VGS-IE using the Rochester Epidemiology Project of Olmsted County, Minnesota. Patient demographics and microbiological data were collected for all VGS-IE cases diagnosed from January 1, 1999, through December 31, 2010. We also examined the Nationwide Inpatient Sample hospital discharge database to determine the number of VGS-IE cases included between 1999 and 2009. We identified 22 cases with VGS-IE in Olmsted County over the 12-year study period. Rates of incidence (per 100 000 person-years) during time intervals of 1999-2002, 2003-2006, and 2007-2010 were 3.19 (95% confidence interval, 1.20-5.17), 2.48 (95% confidence interval, 0.85-4.10), and 0.77 (95% confidence interval, 0.00-1.64), respectively (P=0.061 from Poisson regression). The number of hospital discharges with a VGS-IE diagnosis in the Nationwide Inpatient Sample database during 1999-2002, 2003-2006, and 2007-2009 ranged between 15 318 to 15 938, 16 214 to 17 433, and 14 728 to 15 479, respectively. CONCLUSIONS: On the basis of data complete through 2010, there has been no perceivable increase in the incidence of VGS-IE in Olmsted County, Minnesota, since the publication of the 2007 American Heart Association endocarditis prevention guidelines.

Diagnosis and management of prosthetic joint infection: clinical practice guidelines by the Infectious Diseases Society of America.

These guidelines are intended for use by infectious disease specialists, orthopedists, and other healthcare professionals who care for patients with prosthetic joint infection (PJI). They include evidence-based and opinion-based recommendations for the diagnosis and management of patients with PJI treated with debridement and retention of the prosthesis, resection arthroplasty with or without subsequent staged reimplantation, 1-stage reimplantation, and amputation.

Executive summary: diagnosis and management of prosthetic joint infection: clinical practice guidelines by the Infectious Diseases Society of America.

These guidelines are intended for use by infectious disease specialists, orthopedists, and other healthcare professionals who care for patients with prosthetic joint infection (PJI). They include evidence-based and opinion-based recommendations for the diagnosis and management of patients with PJI treated with debridement and retention of the prosthesis, resection arthroplasty with or without subsequent staged reimplantation, 1-stage reimplantation, and amputation.

Rapid molecular microbiologic diagnosis of prosthetic joint infection.

We previously showed that culture of samples obtained by prosthesis vortexing and sonication was more sensitive than tissue culture for prosthetic joint infection (PJI) diagnosis. Despite improved sensitivity, culture-negative cases remained; furthermore, culture has a long turnaround time. We designed a genus-/group-specific rapid PCR assay panel targeting PJI bacteria and applied it to samples obtained by vortexing and sonicating explanted hip and knee prostheses, and we compared the results to those with sonicate fluid and periprosthetic tissue culture obtained at revision or resection arthroplasty. We studied 434 subjects with knee (n = 272) or hip (n = 162) prostheses; using a standardized definition, 144 had PJI. Sensitivities of tissue culture, of sonicate fluid culture, and of PCR were 70.1, 72.9, and 77.1%, respectively. Specificities were 97.9, 98.3, and 97.9%, respectively. Sonicate fluid PCR was more sensitive than tissue culture (P = 0.04). PCR of prosthesis sonication samples is more sensitive than tissue culture for the microbiologic diagnosis of prosthetic hip and knee infection and provides same-day PJI diagnosis with definition of microbiology. The high assay specificity suggests that typical PJI bacteria may not cause aseptic implant failure.

PCR-electrospray ionization mass spectrometry for direct detection of pathogens and antimicrobial resistance from heart valves in patients with infective endocarditis.

Microbiological diagnosis is pivotal to the appropriate management and treatment of infective endocarditis. We evaluated PCR-electrospray ionization mass spectrometry (PCR/ESI-MS) for bacterial and candidal detection using 83 formalin-fixed paraffin-embedded heart valves from subjects with endocarditis who had positive valve and/or blood cultures, 63 of whom had positive valvular Gram stains. PCR/ESI-MS yielded 55% positivity with concordant microbiology at the genus/species or organism group level (e.g., viridans group streptococci), 11% positivity with discordant microbiology, and 34% with no detection. PCR/ESI-MS detected all antimicrobial resistance encoded by mecA or vanA/B and identified a case of Tropheryma whipplei endocarditis not previously recognized.