Detection of OXA-181 Carbapenemase in Shigella flexneri.

We report the detection of OXA-181 carbapenemase in an azithromycin-resistant Shigella spp. bacteria in an immunocompromised patient. The emergence of OXA-181 in Shigella spp. bacteria raises concerns about the global dissemination of carbapenem resistance in Enterobacterales and its implications for the treatment of infections caused by Shigella bacteria.

Measuring waning protection from seasonal influenza vaccination during nine influenza seasons, Ontario, Canada, 2010/11 to 2018/19.

BackgroundWaning immunity from seasonal influenza vaccination can cause suboptimal protection during peak influenza activity. However, vaccine effectiveness studies assessing waning immunity using vaccinated and unvaccinated individuals are subject to biases.AimWe examined the association between time since vaccination and laboratory-confirmed influenza to assess the change in influenza vaccine protection over time.MethodsUsing linked laboratory and health administrative databases in Ontario, Canada, we identified community-dwelling individuals aged ≥ 6 months who received an influenza vaccine before being tested for influenza by RT-PCR during the 2010/11 to 2018/19 influenza seasons. We estimated the adjusted odds ratio (aOR) for laboratory-confirmed influenza by time since vaccination (categorised into intervals) and for every 28 days.ResultsThere were 53,065 individuals who were vaccinated before testing for influenza, with 10,264 (19%) influenza-positive cases. The odds of influenza increased from 1.05 (95% CI: 0.91-1.22) at 42-69 days after vaccination and peaked at 1.27 (95% CI: 1.04-1.55) at 126-153 days when compared with the reference interval (14-41 days). This corresponded to 1.09-times increased odds of influenza every 28 days (aOR = 1.09; 95% CI: 1.04-1.15). Individuals aged 18-64 years showed the greatest decline in protection against influenza A(H1N1) (aORper 28 days = 1.26; 95% CI: 0.97-1.64), whereas for individuals aged ≥ 65 years, it was against influenza A(H3N2) (aORper 28 days = 1.20; 95% CI: 1.08-1.33). We did not observe evidence of waning vaccine protection for individuals aged < 18 years.ConclusionsInfluenza vaccine protection wanes during an influenza season. Understanding the optimal timing of vaccination could ensure robust protection during seasonal influenza activity.

Disproportionate Rates of COVID-19 Among Black Canadian Communities: Lessons from a Cross-Sectional Study in the First Year of the Pandemic.

BACKGROUND: Racialized communities, including Black Canadians, have disproportionately higher COVID-19 cases. We examined the extent to which SARS-CoV-2 infection has affected the Black Canadian community and the factors associated with the infection. METHODS: We conducted a cross-sectional survey in an area of Ontario (northwest Toronto/Peel Region) with a high proportion of Black residents along with 2 areas that have lower proportions of Black residents (Oakville and London, Ontario). SARS-CoV-2 IgG antibodies were determined using the EUROIMMUN assay. The study was conducted between August 15, 2020, and December 15, 2020. RESULTS: Among 387 evaluable subjects, the majority, 273 (70.5%), were enrolled from northwest Toronto and adjoining suburban areas of Peel, Ontario. The seropositivity values for Oakville and London were comparable (3.3% (2/60; 95% CI 0.4-11.5) and 3.9% (2/51; 95% CI 0.5-13.5), respectively). Relative to these areas, the seropositivity was higher for the northwest Toronto/Peel area at 12.1% (33/273), relative risk (RR) 3.35 (1.22-9.25). Persons 19 years of age or less had the highest seropositivity (10/50; 20.0%, 95% CI 10.3-33.7%), RR 2.27 (1.23-3.59). There was a trend for an interaction effect between race and location of residence as this relates to the relative risk of seropositivity. INTERPRETATION: During the early phases of the pandemic, the seropositivity within a COVID-19 high-prevalence zone was threefold greater than lower prevalence areas of Ontario. Black individuals were among those with the highest seroprevalence of SARS-CoV-2.

Viral dynamics of the SARS-CoV-2 Omicron Variant in Paediatric Patients; A prospective cohort study.

BACKGROUND: There are limited data on the viral dynamics of SARS-CoV-2 in children. Understanding viral load changes over the course of illness and duration of viral shedding may provide insight into transmission dynamics to inform public health and infection control decisions. METHODS: We conducted a prospective cohort study of children 18 years and younger with PCR confirmed SARS-CoV-2 between February 1, 2022 and March 14, 2022. SARS-CoV-2 testing occurred on daily samples for 10 days; a subset of participants completed daily rapid antigen testing (RAT). Viral RNA trajectories were described in relation to symptom onset and resolution. The associations between both time since symptom onset/resolution and non-infectious viral load were evaluated using a Cox proportional hazards model. FINDINGS: Among 101 children aged 2 to 17 years, the median time to study-defined non-infectious viral load was 5 days post symptom onset, with 75% meeting this threshold by 7 days, and 90% by 10 days. On the day of and day after symptom resolution, 43 of 87 (49%) and 52 (60%) had met the non-infectious thresholds, respectively. Of the 50 participants completing RAT, positivity at symptom onset and on the day after symptom onset was 67% (16/24) and 75% (14/20). On the first day where the non-infectious threshold was met, 61% (n = 27/44) of participant RAT results were positive. INTERPRETATION: Children often met the study-defined non-infectiousness threshold on the day after symptom resolution. RAT tests were often negative early in the course of illness and should not be relied on to exclude infection. CLINICAL TRIALS REGISTRATION: NCT05240183.

Effectiveness of maternal influenza vaccination during pregnancy against laboratory-confirmed seasonal influenza among infants under 6 months of age in Ontario, Canada.

BACKGROUND: Randomized trials conducted in low- and middle-income settings demonstrated efficacy of influenza vaccination during pregnancy against influenza infection among infants <6 months of age. However, vaccine effectiveness (VE) estimates from settings with different population characteristics and influenza seasonality remain limited. METHODS: We conducted a test-negative study in Ontario, Canada. All influenza virus tests among infants <6 months from 2010-2019 were identified and linked with health databases to ascertain information on maternal-infant dyads. VE was estimated from the odds ratio for influenza vaccination during pregnancy among cases versus controls, computed using logistic regression with adjustment for potential confounders. RESULTS: Among 23,806 infants tested for influenza, 1,783 (7.5%) were positive and 1,708 (7.2%) were born to mothers vaccinated against influenza during pregnancy. VE against laboratory-confirmed infant influenza infection was 64% (95% confidence interval [CI]: 50%-74%). VE was similar by trimester of vaccination (1st/2nd: 66%, 40%-80%; 3rd: 63%, 46%-74%), infant age at testing (0-<2 months: 63%, 46%-75%; 2-<6 months: 64%, 36%-79%), and gestational age at birth (≥37 weeks: 64%, 50%-75%; < 37 weeks: 61%, 4%-86%). VE against influenza hospitalization was 67% (95%CI: 50%-78%). CONCLUSIONS: Influenza vaccination during pregnancy offers effective protection to infants <6 months, for whom vaccines are not currently available.

Uptake of pertussis immunization in pregnancy and determinants of vaccination in Toronto, Canada.

INTRODUCTION: Pertussis causes significant morbidity and mortality in infants aged <6 months. Maternal pertussis vaccination during pregnancy has been recommended in Canada since 2018 to reduce these negative outcomes. In the absence of routine immunization coverage data, our objective was to evaluate uptake in Toronto, Canada. METHODS: We recruited mother-infant pairs at The Hospital for Sick Children, Toronto, between 2018 and 2020. We performed logistic regression to examine associations between demographics and self-reported pertussis vaccination. RESULTS: 76/243 mothers (31.3 %) reported receiving pertussis vaccination during their most recent pregnancy. Odds of receiving vaccination more than doubled with each 1-year increase in year of pregnancy (aOR: 2.2; 95 % CI: 1.3, 3.6; p < 0.01) and among those born in Canada as compared to those not (aOR: 2.0; 95 % CI: 1.1, 3.6; p = 0.02) CONCLUSION: Uptake of pertussis vaccination during pregnancy in Ontario has increased in recent years, however coverage remains lower than desirable.

A 20-year Study of Intracranial Pyogenic Complications of Sinusitis in Children.

BACKGROUND: Intracranial pyogenic complications of sinusitis in children can lead to serious sequelae. We characterize the clinical, epidemiologic and microbiologic characteristics of children with such complications over a 20-year period. METHODS: Single-center retrospective chart review. Cases were identified based on International Classification of Diseases diagnostic codes (ICD)-9 and ICD-10 depending on the year and by reviewing all intracranial microbiological samples. RESULTS: A total of 104 cases of complicated sinusitis were included after review of 1591 charts. Median age was 12 (IQR 9-14); 72 were male (69%). The most frequent complications were epidural empyema (n = 50, 48%), subdural empyema (n = 46, 44%) and Pott's puffy tumor (n = 27, 26%). 52% (n = 54) underwent neurosurgery and 46% (n = 48) underwent otolaryngological surgery. The predominant pathogen isolated from sterile site specimens was Streptococcus anginosus (n = 40, 63%), but polymicrobial growth was common (n = 24; 38%). The median duration of intravenous antibiotic therapy was 51 days (IQR 42-80). Persistent neurological sequelae (or death, n = 1) were found in 24% (n = 25) and were associated with the presence of cerebritis and extensive disease on neuroimaging ( P = 0.02 and P = 0.04, respectively). CONCLUSIONS: Intracranial complications of sinusitis continue to cause significant morbidity in children. Polymicrobial infections are common, which reinforces the need for broad-spectrum empiric antibiotic therapy and cautious adjustment of the antibiotic regimen based primarily on sterile site cultures. The association of neurologic sequelae with the presence of cerebritis and extensive intracranial involvement on neuroimaging suggest that delayed diagnosis may be a contributor to adverse outcome.

Severe acute hepatitis of unknown etiology in a large cohort of children.

BACKGROUND: We evaluated the proportion, clinical features, and outcomes of previously healthy children presenting to a large Canadian quaternary pediatric center with severe acute hepatitis of unknown etiology. METHODS: All patients with serum alanine aminotransferase (ALT) > 500 U/L or aspartate aminotransferase (AST) > 500 U/L between June 1, 2018, and May 31, 2022, at The Hospital for Sick Children, were identified. Subjects with only AST > 500 U/L were excluded. Clinical characteristics, investigations, and outcomes for patients without clear etiology for ALT > 500 U/L (severe acute hepatitis of unknown etiology) for our study period and from October 1 to May 31 of each year 2018-2021 were reviewed. RESULTS: Of 977 patients with ALT/AST> 500 U/L, 720 had only ALT > 500 U/L. We excluded age below 6 months (n = 99) or above 16 years (n = 66), known pre-existing liver conditions (n = 66), and ALT > 500 U/L in already admitted patients (n = 151). Among the remaining 338 children with ALT > 500 U/L at presentation, an etiology was identified in 303 subjects. 33 (9.8%) children [median age 6.1 y (range 0.5-15.5); 61% male] were confirmed as severe acute hepatitis of unknown etiology. Twenty patients (60.6%) were tested for blood adenovirus by PCR, and 1 (5%) was positive (serotype B7). Liver tissue specimens from 18 patients revealed no evidence of viral inclusions or adenovirus. Twelve (36.3%) presented with pediatric acute liver failure, with 8 (24.2%) requiring liver transplantation. There were no deaths. Hepatitis-associated aplastic anemia occurred in 5 (15%) patients. CONCLUSIONS: Of children presenting with severe acute hepatitis to a quaternary children's hospital over a 48-month period, 9.8% had unknown etiology with no change over time. Liver transplantation remains an important treatment strategy for those presenting with pediatric acute liver failure phenotype. The frequency of cases associated with human adenovirus infection was noncontributory.

Prevalence of Low-Frequency, Antiviral Resistance Variants in SARS-CoV-2 Isolates in Ontario, Canada, 2020-2023.

Importance: Nirmatrelvir-ritonavir is an oral antiviral medication that improves outcomes in SARS-CoV-2 infections. However, there is concern that antiviral resistance will develop and that these viruses could be selected for after treatment. Objective: To determine the prevalence of low-frequency SARS-CoV-2 variants in patient samples that could be selected for by nirmatrelvir-ritonavir. Design, Setting, and Participants: This retrospective cohort study was conducted at 4 laboratories that serve community hospitals, academic tertiary care centers, and COVID-19 assessment centers in Ontario, Canada. Participants included symptomatic or asymptomatic patients who tested positive for SARS-CoV-2 virus and submitted virus samples for diagnostic testing between March 2020 and January 2023. Exposure: SARS-CoV-2 infection. Main Outcomes and Measures: Samples with sufficient viral load underwent next-generation genome sequencing to identify low-frequency antiviral resistance variants that could not be identified through conventional sequencing. Results: This study included 78 866 clinical samples with next-generation whole-genome sequencing data for SARS-CoV-2. Low-frequency variants in the viral nsp5 gene were identified in 128 isolates (0.16%), and no single variant associated with antiviral resistance was predominate. Conclusions and Relevance: This cohort study of low-frequency variants resistant to nirmatrelvir-ritonavir found that these variants were very rare in samples from patients with SARS-CoV-2, suggesting that selection of these variants by nirmatrelvir-ritonavir following the initiation of treatment may also be rare. Surveillance efforts that involve sequencing of viral isolates should continue to monitor for novel resistance variants as nirmatrelvir-ritonavir is used more broadly.

Estimating the Incidence of First RSV Hospitalization in Children Born in Ontario, Canada.

BACKGROUND: Respiratory syncytial virus (RSV) contributes significantly to morbidity in children, placing substantial burdens on health systems, thus RSV vaccine development and program implementation are a public health priority. More data on burden are needed by policymakers to identify priority populations and formulate prevention strategies as vaccines are developed and licensed. METHODS: Using health administrative data, we calculated incidence rates of RSV hospitalization in a population-based birth cohort of all children born over a six-year period (May 2009 to June 2015) in Ontario, Canada. Children were followed until their first RSV hospitalization, death, 5th birthday, or the end of the study period (June 2016). RSV hospitalizations were identified using a validated algorithm based on International Classification of Diseases, 10th Revision, and/or laboratory-confirmed outcomes. We calculated hospitalization rates by various characteristics of interest, including calendar month, age groups, sex, comorbidities, and gestational age. RESULTS: The overall RSV hospitalization rate for children <5 years was 4.2 per 1000 person-years (PY) with a wide range across age groups (from 29.6 to 0.52 per 1000 PY in children aged 1 month and 36-59 months, respectively). Rates were higher in children born at a younger gestational age (23.2 per 1000 PY for those born at <28 weeks versus 3.9 per 1000 PY born at ≥37 weeks); this increased risk persisted as age increased. While the majority of children in our study had no comorbidities, rates were higher in children with comorbidities. For all age groups, rates were highest between December and March. CONCLUSIONS: Our results confirm the high burden of RSV hospitalization and highlight young infants are at additional risk, namely premature infants. These results can inform prevention efforts.

Evaluating the Impact of Statin Use on Influenza Vaccine Effectiveness and Influenza Infection in Older Adults.

BACKGROUND: Older adults are recommended to receive influenza vaccination annually, and many use statins. Statins have immunomodulatory properties that might modify influenza vaccine effectiveness (VE) and alter influenza infection risk. METHODS: Using the test-negative design and linked laboratory and health administrative databases in Ontario, Canada, we estimated VE against laboratory-confirmed influenza among community-dwelling statin users and nonusers aged ≥66 years during the 2010-2011 to 2018-2019 influenza seasons. We also estimated the odds ratio for influenza infection comparing statin users and nonusers by vaccination status. RESULTS: Among persons tested for influenza across the 9 seasons, 54 243 had continuous statin exposure before testing and 48 469 were deemed unexposed. The VE against laboratory-confirmed influenza was similar between statin users and nonusers (17% [95% confidence interval, 13%-20%] and 17% [13%-21%] respectively; test for interaction, P = .87). In both vaccinated and unvaccinated persons, statin users had higher odds of laboratory-confirmed influenza than nonusers (odds ratios for vaccinated and unvaccinated persons 1.15 [95% confidence interval, 1.10-1.21] and 1.15 [1.10-1.20], respectively). These findings were consistent by mean daily dose and statin type. VE did not differ between users and nonusers of other cardiovascular drugs, except for ß-blockers. We did not observe that vaccinated and unvaccinated users of these drugs had increased odds of influenza, except for unvaccinated ß-blocker users. CONCLUSIONS: Influenza VE did not differ between statin users and nonusers. Statin use was associated with increased odds of laboratory-confirmed influenza in vaccinated and unvaccinated persons, but these associations might be affected by residual confounding.

Utility of SARS-CoV-2 Genomic Sequencing for Understanding Transmission and School Outbreaks.

OBJECTIVE: An understanding of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) transmission in schools is important. It is often difficult, using epidemiological information alone, to determine whether cases associated with schools represent multiple introductions from the community or transmission within the school. We describe the use of whole genome sequencing (WGS) in multiple schools to investigate outbreaks of SARS-CoV-2 in the pre-Omicron period. STUDY DESIGN: School outbreaks were identified for sequencing by local public health units based on multiple cases without known epidemiological links. Cases of SARS-CoV-2 from students and staff from 4 school outbreaks in Ontario underwent WGS and phylogenetic analysis. The epidemiological clinical cohort data and genomic cluster data are described to help further characterize these outbreaks. RESULTS: A total of 132 positive SARS-CoV-2 cases among students and staff from 4 school outbreaks were identified with 65 (49%) of cases able to be sequenced with high-quality genomic data. The 4 school outbreaks consisted of 53, 37, 21 and 21 positive cases; within each outbreak there were between 8 and 28 different clinical cohorts identified. Among the sequenced cases, between 3 and 7 genetic clusters, defined as different strains, were identified in each outbreak. We found genetically different viruses within several clinical cohorts. CONCLUSIONS: WGS, together with public health investigation, is a useful tool to investigate SARS-CoV-2 transmission within schools. Its early use has the potential to better understand when transmission may have occurred, can aid in evaluating how well mitigation interventions are working and has the potential to reduce unnecessary school closures when multiple genetic clusters are identified.

Invasive Pneumococcal Disease in High-risk Children: A 10-Year Retrospective Study.

BACKGROUND: Despite the availability of conjugate pneumococcal vaccines, children with high-risk conditions remain vulnerable to invasive pneumococcal disease (IPD). This study sought to describe IPD prevalence, vaccination and outcomes among high-risk children. METHODS: We used International Classification of Disease10 discharge and microbiology codes to identify patients hospitalized for IPD at a large pediatric hospital from January 1, 2009, to December 31, 2018. Patients were considered high-risk if they had: primary immunodeficiency, asplenia, transplant, active malignancy, sickle cell disease, cochlear implant, nephrotic syndrome, chronic lung disease, cerebrospinal fluid leak, HIV or used immunosuppressive therapy. RESULTS: In total 94 high-risk patients were hospitalized for IPD. The most common high-risk conditions included malignancy (n = 33, 35%), solid-organ or bone marrow transplant (n = 17, 18%) and sickle cell disease (n = 14, 15%). Bacteremia was the most common presentation (n = 81, 86%) followed by pneumonia (n = 23, 25%) and meningitis (n = 9, 10%). No deaths occurred. Of 66 patients with known pneumococcal vaccination status, 15 (23%) were unvaccinated, and 51 (77%) received at least one dose of a pneumococcal vaccine; 20 received all four recommended pneumococcal conjugate vaccine (PCV) doses. Only three children received PPSV23. Of 20 children with no or partial (<3 doses) immunization, 70% (14) of IPD episodes were due to vaccine-preventable serotypes. Of 66 known IPD serotypes, 17% (n = 11) were covered by PCV13, 39% (n = 26) were covered by PPSV23 and 39% (n = 26) were nonvaccine serotype. CONCLUSIONS: Despite the availability of effective pneumococcal vaccines, IPD persists among children with high-risk conditions. Improving PCV13 and PPSV23 vaccination could significantly reduce IPD; most episodes were due to vaccine-preventable serotypes in incompletely immunized patients.

Travel-associated extensively drug-resistant typhoid fever: a case series to inform management in non-endemic regions.

BACKGROUND: Extensively drug-resistant (XDR) typhoid fever is a threat to travelers to Pakistan. We describe a multicontinental case series of travel-acquired XDR typhoid fever to demonstrate the global spread of the problem and encourage preventive interventions as well as appropriate empiric antimicrobial use. METHODS: Cases were extracted from the GeoSentinel database, microbiologic laboratory records of two large hospitals in Toronto, Canada, and by invitation to TropNet sites. All isolates were confirmed XDR Salmonella enterica serovar Typhi (Salmonella typhi), with resistance to ampicillin, ceftriaxone, ciprofloxacin and trimethoprim-sulfamethoxazole. RESULTS: Seventeen cases were identified in Canada (10), USA (2), Spain (2), Italy (1), Australia (1) and Norway (1). Patients under 18 years represented 71% (12/17) of cases, and all patients travelled to Pakistan to visit friends or relatives. Only one patient is known to have been vaccinated. Predominant symptoms were fever, abdominal pain, vomiting and diarrhoea. Antimicrobial therapy was started on Day 1 of presentation in 75% (12/16) of patients, and transition to a carbapenem or azithromycin occurred a median of 2 days after blood culture was drawn. Antimicrobial susceptibilities were consistent with the XDR S. typhi phenotype, and whole genome sequencing on three isolates confirmed their belonging to the XDR variant of the H58 clade. CONCLUSIONS: XDR typhoid fever is a particular risk for travelers to Pakistan, and empiric use of a carbapenem or azithromycin should be considered. Pre-travel typhoid vaccination and counseling are necessary and urgent interventions, especially for visiting friends and relatives travelers. Ongoing sentinel surveillance of XDR typhoid fever is needed to understand changing epidemiology.

A Practical Workflow for the Identification of Aspergillus, Fusarium, Mucorales by MALDI-TOF MS: Database, Medium, and Incubation Optimization.

There is an increasing body of literature on the utility of MALDI-TOF MS in the identification of filamentous fungi. However, the process still lacks standardization. In this study, we attempted to establish a practical workflow for the identification of three clinically important molds: Aspergillus, Fusarium, and Mucorales using MALDI-TOF MS. We evaluated the performance of Bruker Filamentous Fungi database v3.0 for the identification of these fungi, highlighting when there would be a benefit of using an additional database, the MSI-2 for further identification. We also examined two other variables, namely, medium effect and incubation time on the accuracy of fungal identification. The Bruker database achieved correct species level identification in 85.7% of Aspergillus and 90% of Mucorales, and correct species-complex level in 94.4% of Fusarium. Analysis of spectra using the MSI-2 database would also offer additional value for species identification of Aspergillus species, especially when suspecting species with known identification limits within the Bruker database. This issue would only be of importance in selected cases where species-level identification would impact therapeutic options. Id-Fungi plates (IDFP) had almost equivalent performance to Sabouraud dextrose agar (SDA) for species-level identification of isolates and enabled an easier harvest of the isolates with occasional faster identification. Our study showed accurate identification at 24 h for Fusarium and Mucorales species, but not for Aspergillus species, which generally required 48 h.

A Prolonged Outbreak of Human Adenovirus A31 (HAdV-A31) Infection on a Pediatric Hematopoietic Stem Cell Transplantation Ward with Whole Genome Sequencing Evidence of International Linkages.

A surge in hematopoietic stem cell transplantation (HSCT) human adenovirus A31 (HAdV-A31) infections was initially observed in late 2014/2015 at SickKids (SK) Hospital, Toronto, Canada. In response, enhanced laboratory monitoring for all adenovirus infections was conducted. Positive samples underwent genotyping, viral culture, and, in selected cases, whole-genome sequencing (WGS). HAdV-A31 specimens/DNA obtained from four international pediatric HSCT centers also underwent WGS. During the SK outbreak period (27 October 2014 to 31 October 2018), 17/20 HAdV-A31 isolates formed a distinct clade with 0 to 8 mutations between the closest neighbors. Surveillance before and after the outbreak detected six additional HAdV-A31 HSCT cases; three of the four sequenced cases clustered within the outbreak clade. Two SK outbreak isolates were identical to sequences from two patients in an outbreak in England. Three SK non-outbreak sequences also had high sequence similarity to strains from three international centers. Environmental PCR testing of the HSCT ward showed significant adenovirus contamination. Despite intense infection control efforts, we observed re-occurrence of infection with the outbreak strain. Severe but nonfatal infection was observed more commonly with HAdV-A31 compared to other genotypes, except HAdV-C1. Our findings strongly implicate nosocomial spread of HAdV-A31 over 10 years on a HSCT unit and demonstrate the value of WGS in defining and mapping the outbreak. Close linkages among strains in different countries suggest international dissemination, though the mechanism is undetermined. This large, extended outbreak emphasizes the pre-eminent role of HAdV-A31 in causing intractable pediatric HSCT outbreaks of severe illness worldwide.

Decreasing Misdiagnoses of Urinary Tract Infections in a Pediatric Emergency Department.

BACKGROUND AND OBJECTIVES: Urinary tract infection (UTI) is a common diagnosis in the emergency department (ED), often resulting in empirical antibiotic treatment before culture results. Diagnosis of a UTI, particularly in children, can be challenging and misdiagnosis is common. The aim of this initiative was to decrease the misdiagnosis of uncomplicated pediatric UTIs by 50% while improving antimicrobial stewardship in the ED over 4 years. METHODS: By using the Model for Improvement, 3 interventions were developed: (1) an electronic UTI diagnostic algorithm, (2) a callback system, and (3) a standardized discharge antibiotic prescription. Outcome measures included the percentage of patients with UTI misdiagnosis (prescribed antibiotics, but urine culture results negative) and antibiotic days saved. As a balancing measure, positive urine culture results without a UTI diagnosis were reviewed for ED return visits or hospitalization. Statistical process control and run charts were used for analysis. RESULTS: From 2017 to 2021, the mean UTI misdiagnosis decreased from 54.6% to 26.4%. The adherence to the standardized antibiotic duration improved from 45.1% to 84.6%. With the callback system, 2128 antibiotic days were saved with a median of 89% of patients with negative culture results contacted to discontinue antibiotics. Of 186 patients with positive urine culture results with an unremarkable urinalysis, 14 returned to the ED, and 2 were hospitalized for multiresistant organism UTI treatment. CONCLUSIONS: A UTI diagnostic algorithm coupled with a callback system safely reduced UTI misdiagnoses and antibiotic usage. Embedding these interventions electronically as a decision support tool, targeted audit and feedback, reminders, and education all supported long-term sustainability.