Machine learning for adverse event prediction in outpatient parenteral antimicrobial therapy: a scoping review.

OBJECTIVE: This study aimed to conduct a scoping review of machine learning (ML) techniques in outpatient parenteral antimicrobial therapy (OPAT) for predicting adverse outcomes and to evaluate their validation, implementation and potential barriers to adoption. MATERIALS AND METHODS: This scoping review included studies applying ML algorithms to adult OPAT patients, covering techniques from logistic regression to neural networks. Outcomes considered were medication intolerance, toxicity, catheter complications, hospital readmission and patient deterioration. A comprehensive search was conducted across databases including Cochrane Central, Cochrane Reviews, Embase, Ovid MEDLINE and Scopus, from 1 January 2000 to 1 January 2024. RESULTS: Thirty-two studies met the inclusion criteria, with the majority being single-centre experiences primarily from North America. Most studies focused on developing new ML models to predict outcomes such as hospital readmissions and medication-related complications. However, there was very little reporting on the performance characteristics of these models, such as specificity, sensitivity and C-statistics. There was a lack of multi-centre or cross-centre validation, limiting generalizability. Few studies advanced beyond traditional logistic regression models, and integration into clinical practice remains limited. DISCUSSION: ML shows promise for enhancing OPAT outcomes by predicting adverse events and enabling pre-emptive interventions. Despite this potential, significant gaps exist in development, validation and practical implementation. Barriers include the need for representative data sets and broadly applicable, validated models. CONCLUSION: Future research should address these barriers to fully leverage ML's potential in optimizing OPAT care and patient safety. Models must deliver timely, accurate and actionable insights to improve adverse event prediction and prevention in OPAT settings.

Personalisation and embodiment in e-Learning for health professionals: A randomised controlled trial.

PURPOSE: Mayer's theory of multimedia learning proposes that personalisation and embodiment (P/E) can improve outcomes in e-Learning. The authors hypothesised that an e-Learning module enhanced by P/E principles would lead to higher knowledge, perceived P/E and motivation among health care professionals, compared with an unenhanced module. METHODS: The authors conducted a randomised trial comparing two versions of a 30-minute multimedia e-Learning module addressing the antibiotic management of pneumonia. The unenhanced format used slides with voiceover (human voice but no visible speaker), formal language and no specific P/E strategies. The enhanced format additionally implemented P/E strategies including conversational style, polite language, visible author, social congruence, human-like presence and professional presence by subtly changing the script and substituting several short videos of subject matter experts. Participants included pharmacists, physicians and advanced practice providers from three academic and several community hospitals. Outcomes included knowledge, perceived P/E (assessed by the Congruence Personalisation Questionnaire, CPQ), motivation (assessed via the Instructional Materials Motivation Survey [IMMS] and Motivated Strategies for Learning Questionnaire [MSLQ]) and course satisfaction. RESULTS: There were 406 participants including 225 pharmacists, 109 physicians and 72 advanced practice providers. Post-module knowledge was slightly higher for the enhanced versus the unenhanced format, but the difference did not reach statistical significance (adjusted mean difference, 0.04 of 10 possible, [95% CI -0.26, 0.34], p = 0.78; Cohen d 0.02). Participant perceptions of P/E (measured via CPQ) were significantly greater for the enhanced format (difference 0.46 of 5 possible [0.35, 0.56], p < 0.001; Cohen d 0.85), as were motivational features of the e-Learning course (measured via IMMS) (difference 0.14 of 5 possible [0.02, 0.26], p = 0.02; Cohen d 0.24). Participants' overall motivational orientation (measured via MSLQ) and course satisfaction were not significantly different between the two formats (p > 0.05). CONCLUSION: Application of P/E principles to an e-Learning module led to greater perceived P/E and motivational features but did not influence knowledge.

Comparison of Oral and Intravenous Definitive Antibiotic Therapy for Beta-Hemolytic Streptococcus Species Bloodstream Infections from Soft Tissue Sources: a Propensity Score-Matched Analysis.

Beta-hemolytic streptococci are common causes of bloodstream infection (BSI). There is emerging data regarding oral antibiotics for BSI but limited for beta-hemolytic streptococcal BSI. We conducted a retrospective study of adults with beta-hemolytic streptococcal BSI from a primary skin/soft tissue source from 2015 to 2020. Patients transitioned to oral antibiotics within 7 days of treatment initiation were compared to those who continued intravenous therapy, after propensity score matching. The primary outcome was 30-day treatment failure (composite of mortality, infection relapse, and hospital readmission). A prespecified 10% noninferiority margin was used for the primary outcome. We identified 66 matched pairs of patients treated with oral and intravenous antibiotics as definitive therapy. Based on an absolute difference in 30-day treatment failure of 13.6% (95% confidence interval 2.4 to 24.8%), the noninferiority of oral therapy was not confirmed (P = 0.741); on the contrary, the superiority of intravenous antibiotics is suggested by this difference. Acute kidney injury occurred in two patients who received intravenous treatment and zero who received oral therapy. No patients experienced deep vein thrombosis or other vascular complications related to treatment. In patients treated for beta-hemolytic streptococcal BSI, those who transitioned to oral antibiotics by day 7 showed higher rates of 30-day treatment failure than propensity-matched patients. This difference may have been driven by underdosing of oral therapy. Further investigation into optimal antibiotic choice, route, and dosing for definitive therapy of BSI is needed.

Impact of the Coronavirus Disease 2019 (COVID-19) Vaccine on Asymptomatic Infection Among Patients Undergoing Preprocedural COVID-19 Molecular Screening.

BACKGROUND: Several vaccines are now available under emergency use authorization in the United States and have demonstrated efficacy against symptomatic COVID-19. Vaccine impact on asymptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is largely unknown. METHODS: We conducted a retrospective cohort study of consecutive, asymptomatic adult patients (n = 39 156) within a large US healthcare system who underwent 48 333 preprocedural SARS-CoV-2 molecular screening tests between 17 December 2020 and 8 February 2021. The primary exposure of interest was vaccination with ≥1 dose of an mRNA COVID-19 vaccine. The primary outcome was relative risk (RR) of a positive SARS-CoV-2 molecular test among those asymptomatic persons who had received ≥1 dose of vaccine compared with persons who had not received vaccine during the same time period. RR was adjusted for age, sex, race/ethnicity, patient residence relative to the hospital (local vs nonlocal), healthcare system regions, and repeated screenings among patients using mixed-effects log-binomial regression. RESULTS: Positive molecular tests in asymptomatic individuals were reported in 42 (1.4%) of 3006 tests and 1436 (3.2%) of 45 327 tests performed on vaccinated and unvaccinated patients, respectively (RR, .44; 95% CI, .33-.60; P < .0001). Compared with unvaccinated patients, risk of asymptomatic SARS-CoV-2 infection was lower among those >10 days after the first dose (RR, .21; 95% CI, .12-.37; P < .0001) and >0 days after the second dose (RR, .20; 95% CI, .09-.44; P < .0001) in the adjusted analysis. CONCLUSIONS: COVID-19 vaccination with an mRNA-based vaccine showed a significant association with reduced risk of asymptomatic SARS-CoV-2 infection as measured during preprocedural molecular screening. Results of this study demonstrate the impact of the vaccines on reduction in asymptomatic infections supplementing the randomized trial results on symptomatic patients.

Myocarditis Following Coronavirus Disease 2019 mRNA Vaccine: A Case Series and Incidence Rate Determination.

BACKGROUND: Myocarditis following coronavirus disease 2019 (COVID-19) mRNA vaccines (Pfizer-BioNTech and Moderna) has been increasingly reported. Incidence rates in the general population are lacking, with pericarditis rather than myocarditis diagnostic codes being used to estimate background rates. This comparison is critical for balancing the risk of vaccination with the risk of no vaccination. METHODS: A retrospective case series was performed using the Mayo Clinic COVID-19 Vaccine Registry. We measured the incidence rate ratio (IRR) for myocarditis temporally related to COVID-19 mRNA vaccination compared with myocarditis in a comparable population from 2016 through 2020. Clinical characteristics and outcomes of the affected patients were collected. A total of 21 individuals were identified, but ultimately 7 patients met the inclusion criteria for vaccine-associated myocarditis. RESULTS: The overall IRR of COVID-19-related myocarditis was 4.18 (95% confidence interval [CI], 1.63-8.98), which was entirely attributable to an increased IRR among adult males (IRR, 6.69; 95% CI, 2.35-15.52) compared with females (IRR 1.41; 95% CI, .03-8.45). All cases occurred within 2 weeks of a dose of the COVID-19 mRNA vaccine, with the majority occurring within 3 days (range, 1-13) following the second dose (6 of 7 patients, 86%). Overall, cases were mild, and all patients survived. CONCLUSIONS: Myocarditis is a rare adverse event associated with COVID-19 mRNA vaccines. It occurs in adult males with significantly higher incidence than in the background population. Recurrence of myocarditis after a subsequent mRNA vaccine dose is not known at this time.

Imported Haycocknema perplexum Infection, United States1.

We report an imported case of myositis caused by a rare parasite, Haycocknema perplexum, in Australia in a 37-year-old man who had progressive facial, axial, and limb weakness, dysphagia, dysphonia, increased levels of creatine kinase and hepatic aminotransferases, and peripheral eosinophilia for 8 years. He was given extended, high-dose albendazole.

Safety and Tolerability of Fluoroquinolones in Patients with Staphylococcal Periprosthetic Joint Infections.

BACKGROUND: Fluoroquinolones (FQs) are known to be accompanied by significant risks. However, the incidence of adverse events (ADEs) resulting in unplanned drug discontinuation when used for periprosthetic joint infections (PJIs) is currently unknown. METHODS: This study included 156 patients over the age of 18 treated for staphylococcal PJI with debridement, antibiotics, and implant retention between 1 January 2007 and 21 November 2019. Of the 156 patients, 64 had total hip arthroplasty (THA) and 92 had total knee arthroplasty (TKA) infections. The primary outcome was rate of unplanned drug discontinuation. Secondary outcomes included incidence of severe ADEs, unplanned rifamycin discontinuation, mean time to unplanned regimen discontinuation, and all-cause mortality. RESULTS: Overall, unplanned drug discontinuation occurred in 35.6% of patients in the FQ group and 3% of patients in the non-FQ group. The rate of unplanned discontinuation of FQ regimens as compared with non-FQ regimens was 27.5% vs 4.2% (P = .021) in THA infections and 42% vs 2.4% (P < .001) in TKA infections. There was no significant difference in severe ADEs between FQ and non-FQ regimens in both THA and TKA infections. The overall rate of nonsevere ADEs in FQ compared with non-FQ regimens was 43.3% vs 6.1% (P < .001). FQs were associated with tendinopathy, myalgia, arthralgia, and nausea. CONCLUSIONS: A significantly higher rate of unplanned drug discontinuation was associated with FQ as compared with non-FQ regimens. This provides a real-world view of the implications of FQ-related ADEs on unplanned discontinuation when used in prolonged durations for the management of staphylococcal PJIs.

Effectiveness of Messenger RNA Coronavirus Disease 2019 (COVID-19) Vaccines Against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection in a Cohort of Healthcare Personnel.

In a large cohort of United States healthcare personnel without prior coronavirus disease 2019 (COVID-19) infection, 94 382 doses of messenger RNA (mRNA) COVID-19 vaccine were administered to 49 220 individuals. The adjusted vaccine effectiveness following 2 doses of each of the 2 available brands of mRNA vaccine exceeded 96%.

Randomized Trial Evaluating Clinical Impact of RAPid IDentification and Susceptibility Testing for Gram-negative Bacteremia: RAPIDS-GN.

BACKGROUND: Rapid blood culture diagnostics are of unclear benefit for patients with gram-negative bacilli (GNB) bloodstream infections (BSIs). We conducted a multicenter, randomized, controlled trial comparing outcomes of patients with GNB BSIs who had blood culture testing with standard-of-care (SOC) culture and antimicrobial susceptibility testing (AST) vs rapid organism identification (ID) and phenotypic AST using the Accelerate Pheno System (RAPID). METHODS: Patients with positive blood cultures with Gram stains showing GNB were randomized to SOC testing with antimicrobial stewardship (AS) review or RAPID with AS. The primary outcome was time to first antibiotic modification within 72 hours of randomization. RESULTS: Of 500 randomized patients, 448 were included (226 SOC, 222 RAPID). Mean (standard deviation) time to results was faster for RAPID than SOC for organism ID (2.7 [1.2] vs 11.7 [10.5] hours; P < .001) and AST (13.5 [56] vs 44.9 [12.1] hours; P < .001). Median (interquartile range [IQR]) time to first antibiotic modification was faster in the RAPID arm vs the SOC arm for overall antibiotics (8.6 [2.6-27.6] vs 14.9 [3.3-41.1] hours; P = .02) and gram-negative antibiotics (17.3 [4.9-72] vs 42.1 [10.1-72] hours; P < .001). Median (IQR) time to antibiotic escalation was faster in the RAPID arm vs the SOC arm for antimicrobial-resistant BSIs (18.4 [5.8-72] vs 61.7 [30.4-72] hours; P = .01). There were no differences between the arms in patient outcomes. CONCLUSIONS: Rapid organism ID and phenotypic AST led to faster changes in antibiotic therapy for gram-negative BSIs. CLINICAL TRIALS REGISTRATION: NCT03218397.

Histoplasmosis in Inflammatory Bowel Disease with Tumor Necrosis Factor-Alpha Inhibitors: Safe to Continue Biologics?

BACKGROUND: The advent of tumor necrosis factor-α (TNF-α) inhibitor therapy has transformed inflammatory bowel disease management; however, these medications carry a boxed warning for risk of serious infections, including invasive fungal infections. AIMS: We aimed to study the clinical features, severity, and outcomes of histoplasmosis in patients on TNF-α inhibitors for IBD. METHODS: We performed a retrospective review of IBD patients receiving TNF-α inhibitors who developed histoplasmosis from January 1, 2001, to May 31, 2018. Patients with drug indications other than ulcerative colitis or Crohn's disease were excluded. IBD was diagnosed histologically, radiographically, or endoscopically. RESULTS: We identified 49 patients (median age 44 years; range 19-76) with histoplasmosis on TNF-α inhibitors. Patients with disseminated disease had a median urine antigen of 10.76 ng/mL compared with pulmonary disease alone 0.375 ng/mL (p < 0.001). Charlson Comorbidity Index and urine antigen levels showed a trend toward predicting disease severity (p > 0.05). Median length of stay was 9.5 days. Itraconazole was used for maintenance in all patients. Median follow-up was 4.7 years. Total treatment duration ranged from 3 to 15 months. TNF-α inhibitor therapy was continued in nine and resumed in ten patients after completing antifungals. Three deaths occurred (6%). CONCLUSIONS: Histoplasmosis outcomes were mostly favorable. Many patients were young with few comorbidities; however, those with more comorbidities experienced more severe histoplasmosis. Compared to prior studies, many of these patients resumed or continued biologic therapy. There were no histoplasmosis recurrences after resuming TNF-α inhibitor therapy. Vigilance for disseminated fungal infections in this patient population is essential.

Cerebral Venous Sinus Thrombosis is not Significantly Linked to COVID-19 Vaccines or Non-COVID Vaccines in a Large Multi-State Health System.

OBJECTIVE: To assess the association of COVID-19 vaccines and non-COVID-19 vaccines with cerebral venous sinus thrombosis (CVST). MATERIALS AND METHOD: We retrospectively analyzed a cohort of 771,805 vaccination events across 266,094 patients in the Mayo Clinic Health System between 01/01/2017 and 03/15/2021. The primary outcome was a positive diagnosis of CVST, identified either by the presence of a corresponding ICD code or by an NLP algorithm which detected positive diagnosis of CVST within free-text clinical notes. For each vaccine we calculated the relative risk by dividing the incidence of CVST in the 30 days following vaccination to that in the 30 days preceding vaccination. RESULTS: We identified vaccination events for all FDA-approved COVID-19 vaccines including Pfizer-BioNTech (n = 94,818 doses), Moderna (n = 36,350 doses) and Johnson & Johnson - J&J (n = 1,745 doses). We also identified vaccinations events for 10 common FDA-approved non-COVID-19 vaccines (n = 771,805 doses). There was no statistically significant difference in the incidence rate of CVST in 30-days before and after vaccination for any vaccine in this population. We further found the baseline CVST incidence in the study population between 2017 and 2021 to be 45 to 98 per million patient years. CONCLUSIONS: This real-world evidence-based study finds that CVST is rare and is not significantly associated with COVID-19 vaccination in our patient cohort. Limitations include the rarity of CVST in our dataset, a relatively small number of J&J COVID-19 vaccination events, and the use of a population drawn from recipients of a SARS-CoV-2 PCR test in a single health system.

Repeat transesophageal echocardiography in infective endocarditis: An analysis of contemporary utilization.

BACKGROUND: Current guidelines from the American Heart Association (AHA) recommend repeating transesophageal echocardiography (TEE) in three to five days if there is high suspicion of IE despite an initial TEE that was negative. This recommendation, however, is based on limited published data. OBJECTIVES: This investigation attempts to identify specific factors that prompted repeat TEE and evaluate the yield of IE-related findings demonstrated by repeat TEE as compared to initial or prior TEE. METHODS: A retrospective cohort who had at least one repeat TEE during an index hospitalization or initial course of antimicrobial therapy for IE between January 2014 and September 2018. We assessed the impact of repeat TEE on IE diagnosis and patient management and included a comparative analysis of patients with initial TEE only. RESULTS: Overall, 59 (44.7%) of 132 IE patients underwent repeat TEE. In a comparative analysis that involved patients who had undergone an initial TEE only versus those who had repeat TEE, male gender (P = .029) and presence of a prosthetic valve or annuloplasty ring (P = .017) were significantly associated with repeat TEE. Importantly, 8 (17.4%) of repeat TEE were critical for IE diagnosis, 8 (17.4%) impacted antimicrobial management, and 11 (23.9%) supported cardiovascular surgical intervention. CONCLUSIONS: From a population-based cohort of incident IE cases, repeat TEE was more frequently (44.7%) done in patients with suspect or proven IE and associated complications than anticipated. Repeat TEE remains pivotal in a contemporary practice that involves critical aspects of IE diagnosis and management.

Destination Joint Spacers, Reinfection, and Antimicrobial Suppression.

In this cohort of 51 patients managed with retained "destination spacers" after the resection of infected joint prostheses, the presence of preoperative sinus drainage was significantly associated with reinfection. Chronic antimicrobial suppression after destination-spacer retention did not significantly prevent reinfections.

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.

Mycobacterium lepromatosis Lepromatous Leprosy in US Citizen Who Traveled to Disease-Endemic Areas.

We report Mycobacterium lepromatosis infection in a US-born person with an extensive international travel history. Clinical symptoms, histopathology, and management are similar to those of infections caused by M. leprae. Clinicians should consider this pathogen in the diagnosis of patients with symptoms of leprosy who have traveled to endemic areas.

Cystatin C-Guided Vancomycin Dosing in Critically Ill Patients: A Quality Improvement Project.

BACKGROUND: The aim of the study was to determine whether a vancomycin dosing algorithm based on estimated glomerular filtration rate from creatinine and cystatin C levels (eGFRcr-cys) improves target trough concentration achievement compared to an algorithm based on estimated creatinine clearance (eCLcr) in critically ill patients. STUDY DESIGN: This prospective quality improvement project evaluated intensive care unit (ICU) patients started on intravenous vancomycin using one of 2 different strategies. Dosing regimens were selected and implemented after an individualized goal trough range was established (10-15 or 15-20mg/L). Steady-state goal trough achievement was compared between treatment arms with and without adjustment for potential confounders. SETTING & PARTICIPANTS: 3 medical and surgical ICUs at a single tertiary medical center. QUALITY IMPROVEMENT PLAN: During January 2012 to October 2013, vancomycin was dosed according to eCLcr using the Cockcroft-Gault formula (control arm). During December 2013 to May 2015, a multidisciplinary quality improvement team implemented a novel vancomycin dosing algorithm according to eGFRcr-cys using the CKD-EPI equation (intervention arm). OUTCOME: Steady-state initial goal vancomycin trough concentration achievement. MEASUREMENTS & RESULTS: More patients in the intervention arm (67 of 135 [50%]) achieved therapeutic trough vancomycin levels than in the control arm (74 of 264 [28%]; OR, 2.53; 95% CI, 1.65-3.90; P<0.001). Improved trough achievement was maintained even after adjustment for age, sex, APACHE (Acute Physiology and Chronic Health Evaluation) III score, fluid balance, baseline CLcr, surgical admission diagnosis, presence of sepsis, and goal trough concentration range (adjusted OR, 2.79; 95% CI, 1.76-4.44; P<0.001). Clinical outcomes were similar between groups. LIMITATIONS: Nonrandomized, incomplete algorithm compliance. CONCLUSIONS: A vancomycin dosing nomogram based on eGFRcr-cys significantly improved goal trough achievement compared to eCLcr among ICU patients with stable kidney function. Further studies are warranted to characterize the relationship between use of cystatin C-guided dosing and clinical outcomes.

Differential Antimicrobial Susceptibilities of Granulicatella adiacens and Abiotrophia defectiva.

MICs of 25 Abiotrophia defectiva and 109 Granulicatella adiacens isolates were determined by broth microdilution. Using CLSI breakpoints, the susceptibilities of A. defectiva and G. adiacens isolates were, respectively, 24% and 34% to penicillin, 92% and 22% to ceftriaxone, 48% and 3% to cefepime, 72% and 87% to meropenem, 92% and 10% to cefotaxime, 100% and 97% to levofloxacin, 92% and 80% to clindamycin, and 24% and 50% to erythromycin. All isolates were susceptible to vancomycin. In the penicillin-susceptible subgroup, all A. defectiva isolates were susceptible to ceftriaxone; however, 62% of G. adiacens isolates were ceftriaxone nonsusceptible.

Mycoplasma hominis vertebral spine infection: Case report and a review of infections of bone and joints.

BACKGROUND: Mycoplasma hominis (M. hominis) is a common commensal that colonizes the human urogenital tract, wherein it is also known to cause genito-urinary infections. It has rarely been reported to cause spinal infections. CASE DESCRIPTION: We describe the case of a 53-year old diabetic woman who developed spontaneous, culture-negative L3-4 osteomyelitis that progressed clinically and radiographically despite debridement, stabilization, and empiric broad-spectrum antimicrobial therapy. After her third debridement procedure, cultures of the multiple intraoperative specimens yielded M. hominis. LITERATURE REVIEW: A PubMed search identified a total of 4 reports of M. hominis causing spinal osteomyelitis and 22 other cases involving bones and joints. CLINICAL RELEVANCE: M. hominis is a rare cause of bone and joint infections. Because of low clinical suspicion for this pathogen, combined with its fastidious nature and the difficult growth characteristics of this organism, M. hominis infections may be unrecognized and untreated, resulting in high morbidity. In addition to bacterial culture, molecular tests are available to detect M. hominis in clinical samples. This case report and review of the literature suggest that, in some cases of purulent culture-negative osteomyelitis, especially if not responding to standard empiric antibacterial therapy, M. hominis should be considered as a potential pathogen.

Streptococcus suis-related prosthetic joint infection and streptococcal toxic shock-like syndrome in a pig farmer in the United States.

Streptococcus suis is an emerging swine-associated zoonotic agent that can cause meningitis and septicemia in humans. We present, to our knowledge, the first case of S. suis arthroplasty infection and streptococcal toxic shock-like syndrome due to an nonencapsulated serotype 5 strain in North America.

Prosthetic joint infection due to Salmonella species: a case series.

BACKGROUND: Prosthetic joint infection (PJI) due to Salmonella is rare. Numerous outbreaks of Salmonella have been reported throughout the United States in the last decade. We reviewed and analyzed cases of Salmonella PJI seen at our institution. METHODS: The medical records of all patients diagnosed with a Salmonella PJI between 1969-2013 were reviewed. Patients were followed till death, treatment failure or loss to follow-up. RESULTS: Six patients of Salmonella PJI were identified during the 44 year study period. Five were male; median age was 63.5 years (range 52-76). Five patients were immunodeficient. Five had a total hip arthroplasty infection, while one had a total knee arthroplasty infection. Median prosthesis age at the time of diagnosis of first episode of Salmonella PJI was 5 years (range 4 months-9 years). Four presented with fever and constitutional signs within two weeks of symptom onset. Two patients each had gastrointestinal symptoms and Salmonella bacteremia. Salmonella enterica serovar Enteritidis was the most common organism isolated (4 patients). None were Salmonella enterica serovar Typhi. Initial management included aspiration and antimicrobial therapy only (3), debridement and component retention (1) and two-staged exchange (2). All four patients treated without resection failed treatment a median of 2.5 months (range 2-11) after diagnosis and required resection arthroplasty. All six patients who underwent prosthesis removal (and exchange or arthrodesis) had successful outcome with a median duration of follow-up of 11 years (range 4-21). Three of these received oral antimicrobial therapy for a median duration eight weeks (range 4-8) and three received parenteral antimicrobial therapy for a median duration of six weeks (range 4-6). CONCLUSIONS: The increase in Salmonella outbreaks does not seem to lead to increased Salmonella PJI. PJIs due to Salmonella remain rare, and the presentation is often acute with fever. It frequently occurs in immunocompromised patients. In our patient population, removal of prosthesis with or without reimplantation, along with 4-6 weeks of effective parenteral antimicrobial therapy was most often associated with successful eradication of infection.