Incidence, Microbiological Studies, and Factors Associated With Prosthetic Joint Infection After Total Knee Arthroplasty.

Importance: Despite the frequency of total knee arthroplasty (TKA) and clinical implications of prosthetic joint infections (PJIs), knowledge gaps remain concerning the incidence, microbiological study results, and factors associated with these infections. Objectives: To identify the incidence rates, organisms isolated from microbiological studies, and patient and surgical factors of PJI occurring early, delayed, and late after primary TKA. Design, Setting, and Participants: This cohort study obtained data from the US Department of Veterans Affairs (VA) Corporate Data Warehouse on patients who underwent elective primary TKA in the VA system between October 1, 1999, and September 30, 2019, and had at least 1 year of care in the VA prior to TKA. Patients who met these criteria were included in the overall cohort, and patients with linked Veterans Affairs Surgical Quality Improvement Program (VASQIP) data composed the VASQIP cohort. Data were analyzed between December 9, 2021, and September 18, 2023. Exposures: Primary TKA as well as demographic, clinical, and perioperative factors. Main Outcomes and Measures: Incident hospitalization with early, delayed, or late PJI. Incidence rate (events per 10 000 person-months) was measured in 3 postoperative periods: early (≤3 months), delayed (between >3 and ≤12 months), and late (>12 months). Unadjusted Poisson regression was used to estimate incidence rate ratios (IRRs) with 95% CIs of early and delayed PJI compared with late PJI. The frequency of organisms isolated from synovial or operative tissue culture results of PJIs during each postoperative period was identified. A piecewise exponential parametric survival model was used to estimate IRRs with 95% CIs associated with demographic and clinical factors in each postoperative period. Results: The 79 367 patients (median (IQR) age of 65 (60-71) years) in the overall cohort who underwent primary TKA included 75 274 males (94.8%). A total of 1599 PJIs (2.0%) were identified. The incidence rate of PJI was higher in the early (26.8 [95% CI, 24.8-29.0] events per 10 000 person-months; IRR, 20.7 [95% CI, 18.5-23.1]) and delayed periods (5.4 [95% CI, 4.9-6.0] events per 10 000 person-months; IRR, 4.2 [95% CI, 3.7-4.8]) vs the late postoperative period (1.3 events per 10 000 person-months). Staphylococcus aureus was the most common organism isolated overall (489 [33.2%]); however, gram-negative infections were isolated in 15.4% (86) of early PJIs. In multivariable analyses, hepatitis C virus infection, peripheral artery disease, and autoimmune inflammatory arthritis were associated with PJI across all postoperative periods. Diabetes, chronic kidney disease, and obesity (body mass index of ≥30) were not associated factors. Other period-specific factors were identified. Conclusions and Relevance: This cohort study found that incidence rates of PJIs were higher in the early and delayed vs late post-TKA period; there were differences in microbiological cultures and factors associated with each postoperative period. These findings have implications for postoperative antibiotic use, stratification of PJI risk according to postoperative time, and PJI risk factor modification.

The Penn Medicine COVID-19 Therapeutics Committee-Reflections on a Model for Rapid Evidence Review and Dynamic Practice Recommendations During a Public Health Emergency.

The Penn Medicine COVID-19 Therapeutics Committee-an interspecialty, clinician-pharmacist, and specialist-front line primary care collaboration-has served as a forum for rapid evidence review and the production of dynamic practice recommendations during the 3-year coronavirus disease 2019 public health emergency. We describe the process by which the committee went about its work and how it navigated specific challenging scenarios. Our target audiences are clinicians, hospital leaders, public health officials, and researchers invested in preparedness for inevitable future threats. Our objectives are to discuss the logistics and challenges of forming an effective committee, undertaking a rapid evidence review process, aligning evidence-based guidelines with operational realities, and iteratively revising recommendations in response to changing pandemic data. We specifically discuss the arc of evidence for corticosteroids; the noble beginnings and dangerous misinformation end of hydroxychloroquine and ivermectin; monoclonal antibodies and emerging viral variants; and patient screening and safety processes for tocilizumab, baricitinib, and nirmatrelvir-ritonavir.

Durability of Severe Acute Respiratory Syndrome Coronavirus 2 Messenger RNA Booster Vaccine Protection Against Omicron Among Healthcare Workers With a Vaccine Mandate.

BACKGROUND: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant has spread rapidly throughout the world since being identified in South Africa in November 2021. Few studies have assessed primary series and booster vaccine effectiveness against Omicron among US healthcare workers. METHODS: We conducted a test-negative case-control design to estimate BNT162b2 and mRNA1273 primary vaccination and booster effectiveness against SARS-CoV-2 infection and symptomatic coronavirus disease 2019 during an Omicron surge among employees of the University of Pennsylvania Health System. The study period was between 1 July 2021 and 5 April 2022. We defined the Delta period as 1 July to 12 December 2021 and the Omicron period as beginning 12 December 21. RESULTS: Our sample included 14 520 tests (2776 [19%] positive)-7422 (506 [7%] positive) during Delta and 7098 (2270 [32%] positive) during Omicron. Benchmarked against Delta, the vaccine effectiveness of 2 vaccine doses was lower during Omicron, with no significant protection against infection. Booster doses added significant protection, although they also showed reduced effectiveness during Omicron. Compared with findings in employees who had received 2 vaccine doses, 3 doses of BNT162b2 had a relative effectiveness of 50% (95% confidence interval, 42%-56%) during Omicron, relative to 78% (63%-87%) during Delta; 3 doses of mRNA1273 had a relative effectiveness of 56% (45%-65%) during Omicron, relative to 96% (82%-99%) during Delta. Restricting the sample to symptomatic tests yielded similar results to our primary analysis. After initial waning in BNT162b2 booster protection against infection, it remained largely stable for ≥16 weeks after vaccination. CONCLUSIONS: Our findings provide a strong rationale for boosters among healthcare workers in the Omicron era.

Development and validation of case-finding algorithms to identify prosthetic joint infections after total knee arthroplasty in Veterans Health Administration data.

PURPOSE: To determine the positive predictive values (PPVs) of ICD-9, ICD-10, and current procedural terminology (CPT)-based diagnostic coding algorithms to identify prosthetic joint infection (PJI) following knee arthroplasty (TKA) within the United States Veterans Health Administration. METHODS: We identified patients with: (1) hospital discharge ICD-9 or ICD-10 diagnosis of PJI, (2) ICD-9, ICD-10, or CPT procedure code for TKA prior to PJI diagnosis, (3) CPT code for knee X-ray within ±90 days of the PJI diagnosis, and (4) at least 1 CPT code for arthrocentesis, arthrotomy, blood culture, or microbiologic procedure within ±90 days of the PJI diagnosis date. Separate samples of patients identified with the ICD-9 and ICD-10-based PJI diagnoses were obtained, stratified by TKA procedure volume at each medical center. Medical records of sampled patients were reviewed by infectious disease clinicians to adjudicate PJI events. The PPV (95% confidence interval [CI]) for the ICD-9 and ICD-10 PJI algorithms were calculated. RESULTS: Among a sample of 80 patients meeting the ICD-9 PJI algorithm, 60 (PPV 75.0%, [CI 64.1%-84.0%]) had confirmed PJI. Among 80 patients who met the ICD-10 PJI algorithm, 68 (PPV 85.0%, [CI 75.3%-92.0%]) had a confirmed diagnosis. CONCLUSIONS: An algorithm consisting of an ICD-9 or ICD-10 PJI diagnosis following a TKA code combined with CPT codes for a knee X-ray and either a relevant surgical procedure or microbiologic culture yielded a PPV of 75.0% (ICD-9) and 85.0% (ICD-10), for confirmed PJI events and could be considered for use in future pharmacoepidemiologic studies.

Blood culture utilization at an academic hospital: Addressing a gap in benchmarking.

OBJECTIVE: To describe the pattern of blood culture utilization in an academic university hospital setting. DESIGN: Retrospective cohort study. SETTING: A 789-bed tertiary-care university hospital that processes 40,000+blood cultures annually. METHODS: We analyzed blood cultures collected from adult inpatients at the Hospital of the University of Pennsylvania between July 1, 2014, and June 30, 2015. Descriptive statistics and regression models were used to analyze patterns of blood culture utilization: frequency of blood cultures, use of repeat cultures following a true-positive culture, and number of sets drawn per day. RESULTS: In total, 38,939 blood culture sets were drawn during 126,537 patient days (incidence rate, 307.7 sets per 1,000 patient days). The median number of blood culture sets drawn per hospital encounter was 2 (range, 1-76 sets). The median interval between blood cultures was 2 days (range, 1-71 days). Oncology services and cultures with gram-positive cocci were significantly associated with greater odds of having repeat blood cultures drawn the following day. Emergency services had the highest rate of drawing single blood-culture sets (16.9%), while oncology services had the highest frequency of drawing ≥5 blood culture sets within 24 hours (0.91%). Approximately 10% of encounters had at least 1 true-positive culture, and 89.2% of those encounters had repeat blood cultures drawn. The relative risk of a patient having repeat blood cultures was lower for those in emergency, surgery, and oncology services than for those in general medicine. CONCLUSIONS: Ordering practices differed by service and culture results. Analyzing blood culture utilization can contribute to the development of guidelines and benchmarks for appropriate usage.

Clostridium difficile-associated diarrhea: an emerging threat to pregnant women.

OBJECTIVE: To estimate if Clostridium difficile-associated disease (CDAD) is increasing in peripartum women. STUDY DESIGN: Peripartum CDAD was assessed through 1) passive surveillance collecting clinical and pathology data on severe cases and 2) survey among infectious disease consultants (ICDs) in the Emerging Infections Network. RESULTS: Ten severe cases were collected; most had associated antibiotic use. Seven women were either admitted to the ICU or underwent colectomy. Three infants were stillborn, and 3 women died. The epidemic Clostridium difficile strain was found in 2 cases. Among 798 ICDs, 419 (52%) participated in the survey. Thirty-seven respondents (9%) recalled 55 cases, mostly in the postpartum period with 21 complications, mainly due to relapse. CONCLUSION: Severe CDAD may be increasing in peripartum women. Clinicians should have a low threshold for testing, be aware of the potential for severe outcomes, and take steps to reduce both the risk of disease and resultant complications.

Neurosyphilis: A Current Review.

Neurosyphilis continues to be a difficult diagnosis for clinicians. The decision to perform a lumbar puncture, interpretation of cerebrospinal fluid findings, clear diagnostic guidelines, establishment of definitive therapy (including alternatives to penicillins), and approach to the follow-up of patients with neurosyphilis are all areas that pose ongoing challenges to clinicians. Coinfection with HIV has also further complicated the already challenging arena of neurosyphilis presentation, diagnosis, and management. Clinicians must recognize the recent changes in the epidemiology of syphilis and know when to initiate appropriate screening. This article highlights the limitations and controversies related to neurosyphilis diagnosis and treatment, and current recommendations on management of patients with neurosyphilis, including those coinfected with HIV.

Misidentification of Mycobacterium peregrinum, the causal organism of a case of bacteremia and automatic implantable cardioverter defibrillator-associated infection, due to its unusual acid-fast staining characteristics.

We report an unusual case of Mycobacterium peregrinum bacteremia and infection of an automatic implantable cardioverter defibrillator that was originally misidentified as a Nocardia sp. due, in part, to its partially acid-fast staining characteristic, morphology, and odor. The misdiagnosis had a direct effect on patient care, though the patient was subsequently successfully treated.

The newer fluoroquinolones.

This article discusses the newer fluoroquinolones in detail with respect to their pharmacokinetics, pharmacodynamics, safety, and spectrum of in vitro activity. The newer agents are compared and contrasted with the older ones, particularly ciprofloxacin. Efficacy of the newer fluoroquinolones when compared with antimicrobial agents in other classes is also presented in detail. Appropriate use of the newer fluoroquinolones is addressed, including their ever expanding role in the treatment of both upper and lower respiratory tract infections and skin and soft tissue infection. Available data on the use of the newer fluoroquinolones in the management of genitourinary tract infections, gastrointestinal infections, and osteomyelitis are also discussed.

Urinary tract infections. How to manage nursing home patients with or without chronic catheterization.

Urinary tract infections (UTIs)--including cystitis, pyelonephritis, and catheter-associated infections--are among the most common nursing home-acquired infections. Asymptomatic bacteriuria can be identified in 20 to 50% of nursing home residents who do not have bladder catheters and in 100% of those who do. Diagnostic tests for nursing home patients with suspected UTI include urinalysis, urine culture, and sensitivity testing. Treatment of cystitis can usually be managed in the nursing home with oral antibiotics. Initial therapy with a parenteral agent is often recommended in nursing home-acquired pyelonephritis.