Prevalence and risk factors for Q fever, spotted fever group rickettsioses, and typhus group rickettsioses in a pastoralist community of northern Tanzania, 2016-2017

BACKGROUND

In northern Tanzania, Q fever, spotted fever group (SFG) rickettsioses, and typhus group (TG) rickettsioses are common causes of febrile illness. We sought to describe the prevalence and risk factors for these zoonoses in a pastoralist community.

METHODS

Febrile patients ≥2 years old presenting to Endulen Hospital in the Ngorongoro Conservation Area were enrolled from August 2016 through October 2017. Acute and convalescent blood samples were collected, and a questionnaire was administered. Sera were tested by immunofluorescent antibody (IFA) IgG assays using Coxiella burnetii (Phase II), Rickettsia africae, and Rickettsia typhi antigens. Serologic evidence of exposure was defined by an IFA titre ≥1:64; probable cases by an acute IFA titre ≥1:128; and confirmed cases by a ≥4-fold rise in titre between samples. Risk factors for exposure and acute case status were evaluated.

RESULTS

Of 228 participants, 99 (43.4%) were male and the median (interquartile range) age was 27 (16-41) years. Among these, 117 (51.3%) had C. burnetii exposure, 74 (32.5%) had probable Q fever, 176 (77.2%) had SFG Rickettsia exposure, 134 (58.8%) had probable SFG rickettsioses, 11 (4.8%) had TG Rickettsia exposure, and 4 (1.8%) had probable TG rickettsioses. Of 146 participants with paired sera, 1 (0.5%) had confirmed Q fever, 8 (5.5%) had confirmed SFG rickettsioses, and none had confirmed TG rickettsioses. Livestock slaughter was associated with acute Q fever (adjusted odds ratio [OR] 2.54, 95% confidence interval [CI] 1.38-4.76) and sheep slaughter with SFG rickettsioses case (OR 4.63, 95% CI 1.08-23.50).

DISCUSSION

Acute Q fever and SFG rickettsioses were detected in participants with febrile illness. Exposures to C. burnetii and to SFG Rickettsia were highly prevalent, and interactions with livestock were associated with increased odds of illness with both pathogens. Further characterisation of the burden and risks for these diseases is warranted.

Utility of Methicillin-Resistant Staphylococcus aureus Nasal PCR Testing in Pediatric Patients With Suspected Respiratory Infections

Observational studies in adults suggest nasal methicillin-resistant Staphylococcus aureus (MRSA) swabs have a high negative predictive value (NPV) for ruling out MRSA pneumonia, however, pediatric data are limited. This retrospective study of 505 pediatric patients found a 99.8% NPV among children with suspected respiratory infections.

Pediatric Antimicrobial Stewardship Programs Reduce Antibiotic Use at Combined Adult-Pediatric Hospitals

Implementation of dedicated pediatric antimicrobial stewardship programs (ASPs) at two combined adult-pediatric hospitals with existing ASPs was associated with sustained decreases in pediatric antibiotic use (AU) out of proportion to declines seen in adult inpatient units. ASPs in combined hospitals may not detect excessive pediatric AU without incorporating pediatric expertise.

Variations in antibiotic prescribing among children enrolled in North Carolina Medicaid, 2013-2019

PURPOSE

The majority of pediatric antibiotic prescribing occurs in the outpatient setting and inappropriate use contributes to antimicrobial resistance. There are regional variations in outpatient antibiotic use with the highest rates occurring in the Southern states, including in Appalachia. The purpose of this study was to describe the rates and risk factors for inappropriate antibiotic prescription among pediatric patients enrolled in North Carolina (NC) Medicaid.

METHODS

We used Medicaid prescription claims data from 2013 to 2019 to describe patterns of pediatric antibiotic prescription in NC. We assessed patient and provider factors to identify variations in prescribing.

FINDINGS

Children who were less than 2 years of age, non-Hispanic White, and living in a rural area had the highest overall rates of antibiotic prescription. Compared to pediatricians, the risk of inappropriate antibiotic prescription was highest among other specialists and general practioners and lowest among nurse practitioners. Rural areas of NC had the highest rates of inappropriate antibiotic prescribing, and the risk for non-Hispanic Black children compared to children of other races/ethnicities was compounded by rurality.

CONCLUSIONS

Prescribing practices in NC differ compared to neighboring states with a lower overall risk of inappropriate prescription in Appalachian regions; however, disparities by race and rurality exist. Outpatient stewardship efforts in NC should focus on ensuring health equity by appreciating racial and geographic variations in prescribing patterns and providing education to all health care providers.

Impact of the COVID-19 Pandemic on Pediatric Preventive Health Care Among North Carolina Children Enrolled in Medicaid

BACKGROUND

Children enrolled in private insurance had reduced preventive health care during the coronavirus disease 2019 (COVID-19) pandemic. However, the impact of the pandemic on children enrolled in Medicaid has been minimally described.

METHODS

We used an administrative claims database from North Carolina Medicaid to evaluate the rates of well-child visits and immunization administration for children ≤14 months of age, and used a quasi-Poisson regression model to estimate the rate ratio (RR) of each outcome during the pandemic period (3/15/2020 through 3/15/2021) compared with the pre-pandemic period (3/15/2019 through 3/14/2020).

RESULTS

We included 83 442 children during the pre-pandemic period and 96 634 children during the pandemic period. During the pre-pandemic period, 405 295 well-child visits and 715 100 immunization administrations were billed; during the pandemic period, 287 285 well-child visits and 457 144 immunization administrations were billed. The rates of well-child visits (RR 0.64; 95% CI, 0.64-0.64) and vaccine administration (RR 0.55; 95% CI, 0.55-0.55) were lower during the pandemic compared with the pre-pandemic period.

CONCLUSIONS

The rates of well-child visits and immunization administrations among North Carolina children enrolled in public insurance substantially decreased during the first year of the COVID-19 pandemic.

Antibacterial Utilization for Febrile Illnesses and Laboratory-Confirmed Bloodstream Infections in Northern Tanzania

Background

We describe antibacterial use in light of microbiology data and treatment guidelines for common febrile syndromes in Moshi, Tanzania.

Methods

We compared data from 2 hospital-based prospective cohort studies, cohort 1 (2011-2014) and cohort 2 (2016-2019), that enrolled febrile children and adults. A study team member administered a standardized questionnaire, performed a physical examination, and collected blood cultures. Participants with bloodstream infection (BSI) were categorized as receiving effective or ineffective therapy based upon antimicrobial susceptibility interpretations. Antibacterials prescribed for treatment of pneumonia, urinary tract infection (UTI), or presumed sepsis were compared with World Health Organization and Tanzania Standard Treatment Guidelines. We used descriptive statistics and logistic regression to describe antibacterial use.

Results

Among participants, 430 of 1043 (41.2%) and 501 of 1132 (44.3%) reported antibacterial use prior to admission in cohorts 1 and 2, respectively. During admission, 930 of 1043 (89.2%) received antibacterials in cohort 1 and 1060 of 1132 (93.6%) in cohort 2. Inpatient use of ceftriaxone, metronidazole, and ampicillin increased between cohorts (P ≤ .002 for each). BSI was detected in 38 (3.6%) participants in cohort 1 and 47 (4.2%) in cohort 2. Of 85 participants with BSI, 81 (95.3%) had complete data and 52 (64.2%) were prescribed effective antibacterials. Guideline-consistent therapy in cohort 1 and cohort 2 was as follows: pneumonia, 87.4% and 56.8%; UTI, 87.6% and 69.0%; sepsis, 84.4% and 61.2% (P ≤ .001 for each).

Conclusions

Receipt of antibacterials for febrile illness was common. While guideline-consistent prescribing increased over time, more than one-third of participants with BSI received ineffective antibacterials.

Racial Inequities in Sepsis Mortality Among Children in the United States

BACKGROUND

Racial inequities influence health outcomes in the United States, but their impact on sepsis outcomes among children is understudied. We aimed to evaluate for racial inequities in sepsis mortality using a nationally representative sample of pediatric hospitalizations.

METHODS

This population-based, retrospective cohort study used the 2006, 2009, 2012 and 2016 Kids' Inpatient Database. Eligible children 1 month to 17 years old were identified using sepsis-related International Classification of Diseases, Ninth Revision or International Classification of Diseases, Tenth Revision codes. We used modified Poisson regression to evaluate the association between patient race and in-hospital mortality, clustering by hospital and adjusting for age, sex and year. We used Wald tests to assess for modification of associations between race and mortality by sociodemographic factors, geographic region and insurance status.

RESULTS

Among 38,234 children with sepsis, 2555 (6.7%) died in-hospital. Compared with White children, mortality was higher among Hispanic (adjusted relative risk: 1.09; 95% confidence interval: 1.05-1.14), Asian/Pacific Islander (1.17, 1.08-1.27) and children from other racial minority groups (1.27, 1.19-1.35). Black children had similar mortality to White children overall (1.02, 0.96-1.07), but higher mortality in the South (7.3% vs. 6.4%; P < 0.0001). Hispanic children had higher mortality than White children in the Midwest (6.9% vs. 5.4%; P < 0.0001), while Asian/Pacific Islander children had higher mortality than all other racial categories in the Midwest (12.6%) and South (12.0%). Mortality was higher among uninsured children than among privately insured children (1.24, 1.17-1.31).

CONCLUSIONS

Risk of in-hospital mortality among children with sepsis in the United States differs by patient race, geographic region and insurance status.

Causal Association of Physician-in-Triage with Improved Pediatric Sepsis Care: A Single-Center, Emergency Department Experience

Approximately 75,000 children are hospitalized for sepsis yearly in the United States, with 5%-20% mortality estimates. Outcomes are closely related to the timeliness of sepsis recognition and antibiotic administration.

Methods

A multidisciplinary sepsis task force formed in the Spring of 2020 aimed to assess and improve pediatric sepsis care in the pediatric emergency department (ED). The electronic medical record identified pediatric sepsis patients from September 2015 to July 2021. Data for time to sepsis recognition and antibiotic delivery were analyzed using statistical process control charts (X̄-S charts). We identified special cause variation, and Bradford-Hill Criteria guided multidisciplinary discussions to identify the most probable cause.

Results

In the fall of 2018, the average time from ED arrival to blood culture orders decreased by 1.1 hours, and the time from arrival to antibiotic administration decreased by 1.5 hours. After qualitative review, the task force hypothesized that initiation of attending-level pediatric physician-in-triage (P-PIT) as a part of ED triage was temporally associated with the observed improved sepsis care. P-PIT reduced the average time to the first provider exam by 14 minutes and introduced a process for physician evaluation before ED room assignment.

Conclusions

Timely assessment by an attending-level physician improves time to sepsis recognition and antibiotic delivery in children who present to the ED with sepsis. Implementing a P-PIT program with early attending-level physician evaluation is a potential strategy for other institutions.

Defining Variability in Evaluation and Management of Children with Chronic Osteomyelitis

Pediatric chronic osteomyelitis is a rare, debilitating condition lacking management guidelines. In a national survey of 162 pediatric infectious disease physicians through the Emerging Infections Network, tremendous variability in diagnostic approaches and management was noted, highlighting a need for a prospective study to better define the spectrum of pathogens and disease.

1164. Antibacterial Utilization for Febrile Illnesses and Laboratory-Confirmed Bloodstream Infections in Northern Tanzania

Background

Antimicrobial resistance is an important cause of morbidity and mortality globally; low- and middle-income countries (LMICs) face an especially high burden. Ineffective antimicrobial prescriptions and use of broad-spectrum agents contribute to resistance. We describe antibacterial prescribing patterns in patients with febrile illnesses and bloodstream infections (BSI) in northern Tanzania.

Methods

We compared data from two hospital-based prospective cohort studies, cohort 1 (2011-2014) and cohort 2 (2016-2019), both enrolled febrile pediatric and adult inpatients in Moshi, Tanzania. Aerobic blood culture was obtained in all patients and standard methods were used to determine isolate antimicrobial susceptibility. To describe management of febrile illness, we analyzed antibacterial drug prescription prior to and after enrollment. Broad-spectrum antibacterials were categorized using published frameworks. Treatments were categorized as discordant if a blood culture isolate was not susceptible to the patient’s antibacterial regimen. We performed descriptive statistics and logistic regression to understand predictors of receiving an antibacterial.

Results

In total, 2,176 febrile inpatients were enrolled. Antibacterials were administered to 430 (42.0%) and 501 (45.1%) patients prior to enrollment, and 930 (89.1%) and 1,060 (93.6%) during admission in cohorts 1 and 2, respectively. Infancy and duration of fever were associated with higher antibacterial prescribing prior to enrollment (Table 2). Broad-spectrum antibacterials were administered to 548 (52.5%) in cohort 1 and 682 (60.2%) in cohort 2. Laboratory-confirmed bacteremia was detected in 87 (4%) patients. Susceptibility results were available in 73 patients; of these, 41 (56.2%) received discordant antibacterials.

Conclusion

Antibacterials were commonly administered for febrile illness in outpatient and inpatient settings; over half of patients received broad-spectrum antibacterials. A high proportion of patients with culture-positive BSI were treated with ineffective antimicrobials. Improved laboratory diagnostics for febrile illness, antimicrobial stewardship interventions, context-specific clinical guidelines, and provider education may improve prescribing practices.

Disclosures

Julian Hertz, MD, Roche Diagnostics: Grant/Research Support.

1314. Defining Variability in the Evaluation and Management of Children with Chronic Osteomyelitis

Background

Pediatric chronic osteomyelitis (COM) is an uncommon, poorly defined, debilitating disorder often requiring multiple surgeries and prolonged antibiotic courses. Serious long-term sequelae may occur. As accepted diagnostic criteria do not exist, assessments of disease incidence, medical/surgical approach to management and outcomes are lacking.

Methods

We created a 14-question web-based survey sent to 390 pediatric infectious disease (PID) physician members of the Emerging Infections Network of the Infectious Diseases Society of America. With no standard definition of COM, respondents were asked to conceptualize this disease as they would during routine clinical practice. Of the 148 (38%) survey respondents so far (Table 1), 126 (85%) reported caring for children with COM. We assessed provider characteristics, diagnostic approach, and site-standard surgical and antibiotic management (including oral and intravenous [IV] antimicrobial choice and duration). We performed descriptive statistics on survey results.

Results

Of the 126 respondents, most were >5 years post-fellowship training and nearly half reported managing 3-6 cases of COM per year (Table 2). Prolonged duration of symptoms (79%), normal inflammatory markers (45%), and abnormal plain films (44%) were the most common findings used for diagnosis; however, diagnostic criteria varied. The most common risk factor was orthopedic implants (44%). Management choices and duration are in Figure 1. Most treated with IV antibiotics for < 2 weeks (34%), continuing oral antibiotics for at least 3-6 months (55%). In COM with retained orthopedic implant, most physicians (48%) use oral therapy until implant removal. Considerations for transition from IV to oral antibiotics included improved physical examination (60%), inflammatory markers (52%), extent of disease (55%), causative organism (41%) and location of infection (38%). Though 85% reported being comfortable diagnosing and managing COM, practices varied widely.

Reported approaches to surgical management (a), duration of IV antibiotics (b), and duration of oral antibiotics (c) in children with COM, and management of COM in patients with implanted hardware (d)

Responses from 126 pediatric infectious diseases physician participating in an Emerging Infections Network survey regarding diagnosis and management of chronic osteomyelitis (COM). Figure 1a) missing data for 2 respondents; figure 1b) missing data for 5 respondents; figure 1c) missing data for 2 respondents; figure 1d) missing data for 9 respondents. COM: Chronic osteomyelitis; IV: intravenous; abx: antibiotics.

Conclusion

Pediatric COM is a complex infection. Formal diagnostic criteria and future prospective studies for medical/surgical management by pathogen/site of infection and presence of foreign material are needed to optimize care and outcomes.

Disclosures

Daniel Benjamin, Jr., MD PhD MPH, Allergan: Advisor/Consultant|Melinta Therapuetics: Advisor/Consultant|Syneos Health: Advisor/Consultant.

Test-to-Stay After SARS-CoV-2 Exposure: A Mitigation Strategy for Optionally Masked K-12 Schools

OBJECTIVES

We evaluated the impact of a test-to-stay (TTS) program on within-school transmission and missed school days in optionally masked kindergarten through 12th grade schools during a period of high community severe acute respiratory syndrome coronavirus 2 transmission.

METHODS

Close contacts of those with confirmed severe acute respiratory syndrome coronavirus 2 infection were eligible for enrollment in the TTS program if exposure to a nonhousehold contact occurred between November 11, 2021 and January 28, 2022. Consented participants avoided school exclusion if they remained asymptomatic and rapid antigen testing at prespecified intervals remained negative. Primary outcomes included within-school tertiary attack rate (test positivity among close contacts of positive TTS participants) and school days saved among TTS participants. We estimated the number of additional school-acquired cases resulting from TTS and eliminating school exclusion.

RESULTS

A total of 1675 participants tested positive or received at least 1 negative test between days 5 and 7 and completed follow-up; 92% were students and 91% were exposed to an unmasked primary case. We identified 201 positive cases. We observed a tertiary attack rate of 10% (95% confidence interval: 6%-19%), and 7272 (89%) of potentially missed days were saved through TTS implementation. We estimated 1 additional school-acquired case for every 21 TTS participants remaining in school buildings during the entire study period.

CONCLUSIONS

Even in the setting of high community transmission, a TTS strategy resulted in substantial reduction in missed school days in optionally masked schools.

Test-to-Stay After Exposure to SARS-CoV-2 in K-12 Schools

OBJECTIVES

We evaluated the safety and efficacy of a test-to-stay program for unvaccinated students and staff who experienced an unmasked, in-school exposure to someone with confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Serial testing instead of quarantine was offered to asymptomatic contacts. We measured secondary and tertiary transmission rates within participating schools and in-school days preserved for participants.

METHODS

Participating staff or students from universally masked districts in North Carolina underwent rapid antigen testing at set intervals up to 7 days after known exposure. Collected data included location or setting of exposure, participant symptoms, and school absences up to 14 days after enrollment. Outcomes included tertiary transmission, secondary transmission, and school days saved among test-to-stay participants. A prespecified interim safety analysis occurred after 1 month of enrollment.

RESULTS

We enrolled 367 participants and completed 14-day follow-up on all participants for this analysis. Nearly all (215 of 238, 90%) exposure encounters involved an unmasked index case and an unmasked close contact, with most (353 of 366, 96%) occurring indoors, during lunch (137 of 357, 39%) or athletics (45 of 357, 13%). Secondary attack rate was 1.7% (95% confidence interval: 0.6%-4.7%) based on 883 SARS-CoV-2 serial rapid antigen tests with results from 357 participants; no tertiary cases were identified, and 1628 (92%) school days were saved through test-to-stay program implementation out of 1764 days potentially missed.

CONCLUSION

After unmasked in-school exposure to SARS-CoV-2, even in a mostly unvaccinated population, a test-to-stay strategy is a safe alternative to quarantine.

A School-Based SARS-CoV-2 Testing Program: Testing Uptake and Quarantine Length After In-School Exposures

OBJECTIVES

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-related quarantines, which are required after close contact with infected individuals, have substantially disrupted in-person education for kindergarten through 12th grade (K-12) students. In recent recommendations, shortened durations of quarantine are allowed if a negative SARS-CoV-2 test result is obtained at 5 to 7 days postexposure, but access to testing remains limited. We hypothesized that providing access to in-school SARS-CoV-2 testing postexposure would increase testing and reduce missed school days.

METHODS

This prospective cohort study was conducted in one large public K-12 school district in North Carolina and included 2 periods: preimplementation (March 15, 2021, to April 21, 2021) and postimplementation (April 22, 2021, to June 4, 2021), defined around initiation of an in-school SARS-CoV-2 testing program in which on-site access to testing is provided. Number of quarantined students and staff, testing uptake, test results, and number of missed school days were analyzed and compared between the preimplementation and postimplementation periods.

RESULTS

Twenty-four schools, including 12 251 in-person learners, participated in the study. During preimplementation, 446 close contacts were quarantined for school-related exposures; 708 close contacts were quarantined postimplementation. Testing uptake after school-related exposures increased from 6% to 40% (95% confidence interval: 23% to 45%) after implementation, and 89% of tests were conducted in-school. After in-school testing implementation, close contacts missed ∼1.5 fewer days of school (95% confidence interval: -2 to -1).

CONCLUSIONS

Providing access to in-school testing may be a worthwhile mechanism to increase testing uptake after in-school exposures and minimize missed days of in-person learning, thereby mitigating the pandemic's ongoing impact on children.

Masking Adherence in K-12 Schools and SARS-CoV-2 Secondary Transmission

OBJECTIVES

Masking is an essential coronavirus 2019 mitigation tool assisting in the safe return of kindergarten through 12th grade children and staff to in-person instruction; however, masking adherence, compliance evaluation methods, and potential consequences of surveillance are currently unknown. We describe 2 school districts' approaches to promote in-school masking and the consequent impact on severe acute respiratory syndrome coronavirus 2 secondary transmission.

METHODS

Two North Carolina school districts developed surveillance programs with daily versus weekly interventions to monitor in-school masking adherence. Safety teams recorded the proportion of students and staff appropriately wearing masks and provided real-time education after observation of improper masking. Primary infections, within-school transmission, and county-level severe acute respiratory syndrome coronavirus 2 infection rates were assessed.

RESULTS

Proper mask use was high in both intervention groups and districts. There were variations by grade level, with lower rates in elementary schools, and proper adherence being higher in the weekly surveillance group. Rates of secondary transmission were low in both districts with surveillance programs, regardless of intervention frequency.

CONCLUSIONS

Masking surveillance interventions are effective at ensuring appropriate masking at all school levels. Creating a culture of safety within schools led by local leadership is important and a feasible opportunity for school districts with return to in-person school. In our study of schools with high masking adherence, secondary transmission was low.

Building a National Framework to Pair Scientists and Schools During a Global Pandemic

The coronavirus disease 2019 (COVID-19) pandemic forced the suspension of in-person education in schools serving students in kindergarten through 12th grade (K-12) across the United States. As time passed, teachers, students, and parents struggled with remote education. With limited guidance at the federal level, physicians and school leaders across the country collaborated to develop local solutions for schools. This article describes the lessons learned from the development of 4 academic-community partnerships and collaboration among these partnerships to provide national leadership on managing COVID-19 mitigation in the K-12 environment. In addition, we describe a pathway forward for using academic-community partnerships to improve child health.

Safety and Pharmacokinetics of Exebacase in an Infant With Disseminated Staphylococcus aureus Infection

Exebacase, an antistaphylococcal lysin produced from a bacteriophage-encoded gene, is a promising adjunctive therapy for severe methicillin-resistant Staphylococcus aureus infections. We describe the first infant to receive exebacase, dosing, and pharmacokinetics. Exebacase may be safe and efficacious in children; however, further clinical trials are needed to optimize dosing.

Community SARS-CoV-2 Surge and Within-School Transmission

OBJECTIVES

When the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic began, experts raised concerns about in-person instruction in the setting of high levels of community transmission. We describe secondary transmission of SARS-CoV-2 within North Carolina kindergarten through 12th-grade school districts during a winter surge to determine if mitigation strategies can hinder within-school transmission.

METHODS

From October 26, 2020, to February 28, 2021, 13 North Carolina school districts participating in The ABC Science Collaborative were open for in-person instruction, adhered to basic mitigation strategies, and tracked community- and school-acquired SARS-CoV-2 cases. Public health officials adjudicated each case. We combined these data with that from August 2020 to evaluate the effect of the SARS-CoV-2 winter surge on infection rates as well as weekly community- and school-acquired cases. We evaluated the number of secondary cases generated by each primary case as well as the role of athletic activities in school-acquired cases.

RESULTS

More than 100 000 students and staff from 13 school districts attended school in person; of these, 4969 community-acquired SARS-CoV-2 infections were documented by molecular testing. Through contact tracing, North Carolina local health department staff identified an additional 209 infections among >26 000 school close contacts (secondary attack rate <1%). Most within-school transmissions in high schools (75%) were linked to school-sponsored sports. School-acquired cases slightly increased during the surge; however, within-school transmission rates remained constant, from presurge to surge, with ∼1 school-acquired case for every 20 primary cases.

CONCLUSIONS

With adherence to basic mitigation strategies, within-school transmission of SARS-CoV-2 can be interrupted, even during a surge of community infections.

Skeletal muscle and plasma concentrations of cefazolin during complex paediatric spinal surgery

BACKGROUND

Surgical site infections (SSIs) can have devastating consequences for children who undergo spinal instrumentation. Prospective evaluations of prophylactic cefazolin in this population are limited. The purpose of this study was to describe the pharmacokinetics and skeletal muscle disposition of prophylactic cefazolin in a paediatric population undergoing complex spinal surgery.

METHODS

This prospective pharmacokinetic study included 17 children with adolescent idiopathic scoliosis undergoing posterior spinal fusion, with a median age of 13.8 [interquartile range (IQR) 13.4-15.4] yr and a median weight of 60.6 (IQR 50.8-66.0) kg. A dosing strategy consistent with published guidelines was used. Serial plasma and skeletal muscle microdialysis samples were obtained during the operative procedure and unbound cefazolin concentrations measured. Non-compartmental pharmacokinetic analyses were performed. The amount of time that the concentration of unbound cefazolin exceeded the minimal inhibitory concentration for bacterial growth for selected SSI pathogens was calculated.

RESULTS

Skeletal muscle concentrations peaked at a median of 37.6 (IQR 26.8-40.0) µg ml(-1) within 30-60 min after the first cefazolin 30 mg kg(-1) dose. For patients who received a second 30 mg kg(-1) dose, the peak concentrations reached a median of 40.5 (IQR 30.8-45.7) µg ml(-1) within 30-60 min. The target cefazolin concentrations for SSI prophylaxis for meticillin-sensitive Staphylococcus aureus (MSSA) and Gram-negative pathogens were exceeded in skeletal muscle 98.9 and 58.3% of the intraoperative time, respectively.

CONCLUSIONS

For children with adolescent idiopathic scoliosis undergoing posterior spinal fusion, the cefazolin dosing strategy used in this study resulted in skeletal muscle concentrations that were likely not to be effective for intraoperative SSI prophylaxis against Gram-negative pathogens.

Urine assay for tenofovir to monitor adherence in real time to tenofovir disoproxil fumarate/emtricitabine as pre-exposure prophylaxis

OBJECTIVES

Tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) is approved for pre-exposure prophylaxis (PrEP) against HIV infection. Adherence is critical for the success of PrEP, but current adherence measurements are inadequate for real-time adherence monitoring. We developed and validated a urine assay to measure tenofovir (TFV) to objectively monitor adherence to PrEP.

METHODS

We developed a urine assay using high-performance liquid chromatography coupled to tandem mass spectrometry with high sensitivity/specificity for TFV that allowed us to determine TFV concentrations in log₁₀ categories between 0 and 10 000 ng/mL. We validated the assay in three cohorts: (1) HIV-positive subjects with undetectable viral loads on a TDF/FTC-based regimen, (2) healthy HIV-negative subjects who received a single dose of TDF/FTC, and (3) HIV-negative subjects receiving daily TDF/FTC as PrEP for 24 weeks.

RESULTS

The urine assay detected TFV with greater sensitivity than plasma-based measures and with a window of measurements within 7 days of the last TDF/FTC dose. Based on the urine log-linear clearance after the last dose and its concordance with all detectable plasma levels, a urine TFV concentration > 1000 ng/mL was identified as highly predictive of the presence of TFV in plasma at > 10 ng/mL. The urine assay was able to distinguish high and low adherence patterns within the last 48 h (> 1000 ng/mL versus 10-1000 ng/mL), as well as nonadherence (< 10 ng/mL) extended over at least 1 week prior to measurement.

CONCLUSIONS

We provide proof of concept that a semiquantitative urine assay measuring levels of TFV could be further developed into a point-of-care test and be a useful tool to monitor adherence to PrEP.