Postdiscontinuation Antibiotic Exposure in Hospitalized Infants at Risk for Late-onset Sepsis in the Neonatal Intensive Care Unit.

BACKGROUND: In the neonatal intensive care unit, infants are at risk for late-onset sepsis. When blood cultures are negative, antibiotic stewardship efforts encourage stopping antibiotics, yet the duration of therapeutic exposure after the last dose is unknown. METHODS: This retrospective cohort study of simulated antibiotic exposures used published population pharmacokinetic models within drug-specific neonatal intensive care unit cohorts of preterm and term infants, postnatal age 7-60 days and exposed to cefepime, piperacillin-tazobactam or tobramycin. Monte Carlo simulations (NONMEM 7.3) were used to predict steady-state exposures after a 72-hour antibiotic course per Neofax dosing. Exposure was assessed relative to drug-specific minimum inhibitory concentration (MIC) targets between 1 and 16 mcg/mL for Pseudomonas and Enterobacteriaceae species. Postdiscontinuation antibiotic exposure (PDAE) was defined as the time from the last dose to when antibiotic concentration decreased below a specific MIC. RESULTS: Piperacillin-tazobactam, cefepime and tobramycin cohorts included infants with median gestation age 29, 32 and 32 weeks and postnatal age 17, 19 and 15 days, respectively. The mean PDAE was 19-68 hours, depending on the specific antibiotic/MIC combination. PDAE was longer for infants <28 days old and preterm (vs. term) infants. Cefepime exhibited the longest mean PDAE of 68 hours for Enterobacteriaceae MIC 1. Piperacillin mean PDAE was 25 hours for Enterobacteriaceae MIC 8. Tobramycin had a short mean PDAE of 19 hours. CONCLUSIONS: Piperacillin and cefepime exposures remained therapeutic long after the expected 8- to 12-hour dosing interval. PDAE is an important consideration for antibiotic stewardship among hospitalized infants, particularly premature infants and those within 1 month postbirth.

Antibiotic Use Among Infants Admitted to Neonatal Intensive Care Units.

This cross-sectional study examines antibiotic exposure, days of therapy, types of antibiotics, and changes in use patterns among newborns in neonatal intensive care units (NICUs) across the US from 2009 to 2021.

Measles Serostatus Among Parturient Patients at 2 Philadelphia Hospitals in 2021.

This observational study explores whether rubella serostatus, which is routinely assessed during pregnancy, can serve as a proxy for measles serostatus in parturient persons.

Preterm infants at low risk for early-onset sepsis differ in early fecal microbiome assembly.

Antibiotics are administered near-universally to very low birth weight (VLBW) infants after birth for suspected early-onset sepsis (EOS). We previously identified a phenotypic group of VLBW infants, referred to as low-risk for EOS (LRE), whose risk of EOS is low enough to avoid routine antibiotic initiation. In this cohort study, we compared 18 such infants with 30 infants categorized as non-LRE to determine if the lower risk of pathogen transmission at birth is accompanied by differences in microbiome acquisition and development. We did shotgun metagenomic sequencing of 361 fecal samples obtained serially. LRE infants had a higher human-to-bacterial DNA ratio than non-LRE infants in fecal samples on days 1-3 after birth, confirming lower bacterial acquisition among LRE infants. The microbial diversity and composition in samples from days 4-7 differed between the groups with a predominance of Staphylococcus epidermidis in LRE infants and Enterobacteriaceae sp. in non-LRE infants. Compositional differences were congruent with the distribution of virulence factors and antibiotic resistant genes. After the first week, the overall composition was similar, but changes in relative abundance for several taxa with increasing age differed between groups. Of the nine late-onset bacteremia episodes, eight occurred in non-LRE infants. Species isolated from the blood culture was detected in the pre-antibiotic fecal samples of the infant for all episodes, though these species were also found in infants without bacteremia. In conclusion, LRE infants present a distinct pattern of microbiome development that is aligned with their low risk for EOS. Further investigation to determine the impact of these differences on later outcomes such as late-onset bacteremia is warranted.

Breast Milk and Saliva for Postnatal Cyto†megalovirus Screening among Very Low Birth Weight Infants.

BACKGROUND: The optimal approach to managing postnatal cytomegalovirus disease (pCMV) among very low birth weight (VLBW) infants remains unknown. Methods to facilitate screening are needed. OBJECTIVE: Determine whether mother's milk and infant saliva can be used to reliably identify maternal cytomegalovirus (CMV) serostatus and detect infant pCMV acquisition. METHODS: This was a single-center, prospective cohort study of VLBW infants, and their mothers, born between 2017 and 2020. Maternal milk samples were tested for CMV immunoglobulin G (IgG) using a CMV glycoprotein B binding enzyme-linked immunosorbent assay and the results were compared with maternal serum CMV IgG results. Biweekly paired saliva and urine samples were collected from infants born to mothers with positive or unknown CMV serostatus. Saliva samples were tested for CMV DNA by quantitative real-time polymerase chain reaction (PCR) and compared with urine CMV qualitative PCR results obtained from a clinical laboratory. RESULTS: Among 108 infants without congenital CMV included in the study, 10 (9%) acquired pCMV. Both milk and blood CMV serology results were available for 70 mothers. Maternal milk antibody testing had a sensitivity of 97.2% (95% CI: 85.5-99.9%) and specificity of 91.2% (95% CI: 76.3-98.1%) in establishing CMV serostatus. Paired serially collected saliva and urine samples (n = 203) were available for 66 infants. Saliva PCR had a sensitivity of 30.0% (95% CI: 6.7-65.2%) and specificity of 92.7% (95% CI: 88.1-96.0%) in detecting pCMV acquisition. CONCLUSIONS: Maternal breast milk is a reliable alternative sample to determine CMV serostatus. Serial testing of infant saliva was not adequately sensitive for identifying pCMV acquisition in preterm infants.

Ampicillin dosing in premature infants for early-onset sepsis: exposure-driven efficacy, safety, and stewardship.

OBJECTIVE: Define optimal ampicillin dosing for empiric early-onset sepsis (EOS) therapy in preterm neonates. STUDY DESIGN: We simulated ampicillin concentrations in newborns (birthweight < 1500 g; gestational age 22-27 weeks), summarizing three 48 h regimens: high 100 mg/kg Q8hr, medium 100 mg/kg Q12hr, and standard 50 mg/kg Q12hr. Concentration data were analyzed for concentration above minimum inhibitory concentration (MIC), below neurotoxicity threshold (Cmax ≤ 140 mcg/mL), and duration limited to 48 h. RESULTS: Among 34,689 newborns, all dosing regimens provided concentrations above MIC through 48 h, but Cmax exceeded the neurotoxicity threshold. With the 4-dose standard regimen, >90% maintained concentrations >MIC beyond 48 h. With the 2-dose regimen, newborns maintained the mean concentration >MIC within the 48 h culture window and below neurotoxicity level. Infants 22-24 weeks' gestation had higher drug concentrations and more prolonged exposure duration than 25-27 weeks' gestation. CONCLUSIONS: For EOS in preterm infants, two ampicillin doses (50 mg/kg) provided optimal bactericidal exposures, while minimizing potential toxicity.

Challenges and opportunities for improving access to approved neonatal drugs and devices.

Neonatal drug and device development has lagged behind other patient populations. Oftentimes, providers are using drugs and devices without adequate study of safety and efficacy. Neonates deserve dedicated drug and device development programs, which will require novel approaches and unique collaborations between multiple key stakeholders. Legislative efforts, infrastructure, clinical trial methodology, and international collaborations have all contributed to improvements in neonatal drug and device development, but more work is still needed. Leadership from neonatologists, clinical care providers, and parents is essential to implement needed changes.

Immunization in the Neonatal Intensive Care Unit.

Premature infants admitted to the neonatal intensive care unit are at risk for severe infections and infectious complications caused by vaccine-preventable diseases. Both maternal and neonatal vaccination prevent such infections and improve outcomes for premature infants. An understanding of vaccine efficacy, safety, and administration recommendations, as well as reasons for vaccine hesitancy among clinicians and caregivers, facilitate strategies for improving vaccination rates for infants in the neonatal intensive care unit. Timely vaccination of premature infants confers important protection and improves vaccination rates during childhood.

Prolonged Post-Discontinuation Antibiotic Exposure in Very Low Birth Weight Neonates at Risk for Early-Onset Sepsis.

BACKGROUND: Premature, very low birth weight (VLBW) neonates are at risk for early-onset sepsis and receive ampicillin and gentamicin post-birth. Antimicrobial stewardship supports short-course antibiotics, but how long antibiotic concentrations remain therapeutic post-last dose is unknown. METHODS: Using Monte Carlo simulations (NONMEM 7.3), we analyzed antibiotic exposures in a retrospective cohort of 34 689 neonates (<1500 g, 22-27 weeks of gestation). Therapeutic exposure for ampicillin and gentamicin was evaluated relative to the minimum inhibitory concentration (MIC) for common pathogens (MIC 0.25-8 mcg/mL for group B streptococcus [GBS] and Escherichia coli). Post-discontinuation antibiotic exposure (PDAE) was defined as the time from the last dose to time when concentration decreased below MIC. RESULTS: Neonates had a median (range) gestational age of 26 (22-27) weeks and BW, 790 g (400-1497) . All ampicillin dosing regimens (50-100 mg/kg every 8-12 hours for 2-6 doses) achieved therapeutic exposures > MIC range. After the last dose, the PDAE mean (95% confidence interval [CI]) ranged from 34 to 50 hours (17-79) for E. coli (MIC 8) and 82 to 104 hours (95% CI: 39-122) for GBS (MIC 0.25); longer PDAE occurred with higher dose, shorter interval, and longer course. Short-course ampicillin (2 doses, 50 mg/kg every 12 hours) provided PDAE 34 hours for E. coli and 82 hours for GBS. Single-dose 5 mg/kg gentamicin provided PDAE > MIC 2 for 26 hours. CONCLUSIONS: In VLBW neonates, ampicillin exposure remains therapeutic long after the last dose. Short-course ampicillin provided therapeutic exposures throughout the typical blood culture incubation period.

Clinical impact of neonatal hypoglycemia screening in the well-baby care.

OBJECTIVES: To determine the proportion of well-appearing newborns screened for hypoglycemia, yield of specific screening criteria, and impact of screening on breastfeeding. STUDY DESIGN: The retrospective study of well-appearing at-risk infants born ≥36 weeks' gestation with blood glucose (BG) measurements obtained ≤72 h of age. RESULTS: Of 10,533 eligible well newborns, 48.7% were screened for hypoglycemia. Among tested infants, BG < 50 mg/dL occurred in 43% and 4.6% required intensive care for hypoglycemia. BG < 50 mg/dL was associated with lower rates of exclusive breastfeeding (22% vs 65%, p < 0.001). Infants screened due to late-preterm birth were most frequently identified as hypoglycemic. The fewest abnormal values occurred among appropriate weight, late-term infants of nondiabetic mothers. CONCLUSION: Hypoglycemia risk criteria result in screening a large proportion of otherwise well newborns and negatively impact rates of exclusive breastfeeding. The risks and benefits of hypoglycemia screening recommendations should be urgently addressed.

Dosing and Safety of Off-label Use of Caffeine Citrate in Premature Infants.

OBJECTIVE: To characterize the dosing and safety of off-label caffeine citrate in a contemporary cohort of extremely premature infants. STUDY DESIGN: We used electronic health records (2010-2013) from 4 neonatal intensive care units to identify infants of ≤28 weeks of gestational age exposed to caffeine citrate. Safety outcomes included death, bronchopulmonary dysplasia, necrotizing enterocolitis, spontaneous intestinal perforation, intraventricular hemorrhage, patent ductus arteriosus ligation, seizures, and arrhythmias. We used multivariable logistic regression to evaluate the association of caffeine citrate exposure with clinical events. RESULTS: Of 410 infants with a median (IQR) gestational age of 26 (24-27) weeks, 95% received caffeine citrate for >0 days. Infants received a median (IQR) daily dose of 8 (5-10) mg/kg/day. Incidences of clinical events on day of caffeine citrate exposure were death 2%, patent ductus arteriosus ligation 12%, and medical and surgical necrotizing enterocolitis 5% and 4%, respectively. Bronchopulmonary dysplasia occurred in 37% of infants and was not associated with caffeine dose. Increased caffeine citrate dose was associated with lower odds of patent ductus arteriosus ligation and necrotizing enterocolitis. CONCLUSIONS: Caffeine citrate was used in extremely premature infants at younger gestation, at higher doses, and for longer durations than recommended on the drug label. Increased caffeine citrate exposure, dose, or therapy duration was not associated with increased risk of necrotizing enterocolitis.

Physiologically-Based Pharmacokinetic Modeling of Fluconazole Using Plasma and Cerebrospinal Fluid Samples From Preterm and Term Infants.

Fluconazole is used to treat hematogenous Candida meningoencephalitis in preterm and term infants. To characterize plasma and central nervous system exposure, an adult fluconazole physiologically-based pharmacokinetic (PBPK) model was scaled to infants, accounting for age dependencies in glomerular filtration and metabolism. The model was optimized using 760 plasma samples from 166 infants (median postmenstrual age (range) 28 weeks (24-50)) and 27 cerebrospinal fluid (CSF) samples from 22 infants (postmenstrual age 28 weeks (24-33)). Simulations evaluated achievement of the surrogate efficacy target of area under the unbound concentration-time curve ≥ 400 mg • hour/L over the dosing interval in plasma and CSF using dosing guidelines. Average fold error of predicted concentrations was 0.73 and 1.14 for plasma and CSF, respectively. Target attainment in plasma and CSF was reached faster after incorporating a loading dose of 25 mg/kg. PBPK modeling can be useful in exploring CNS kinetics of drugs in children.

Drugs for the Prevention and Treatment of Sepsis in the Newborn.

Antimicrobial medications are the most commonly used medications in the neonatal intensive care unit. Antibiotics are used for infection prophylaxis, empiric treatment, and definitive treatment of confirmed infection. The choice of medication should be informed by the epidemiology and microbiology of infection in specific clinical scenarios and by the clinical condition of the infant. Understanding evolving pathogen susceptibility to antimicrobials and key pharmacotherapy determinants in neonates can inform optimal antibiotic use.

Factors in Premature Infants Associated With Low Risk of Developing Retinopathy of Prematurity.

Importance: Most premature infants will not develop retinopathy of prematurity (ROP) of clinical relevance, yet screening evaluations often continue beyond hospital discharge, even for those infants without ROP. Objectives: To identify the characteristics of infants at low risk for ROP, for whom further postdischarge screening may be of limited value. Design, Setting, and Participants: This study took place in North American neonatal intensive care units where clinicians had expertise in ROP. Infants with birth weight less than 1251 g who were born at or transferred into an Telemedicine Approaches to Evaluating Acute-Phase ROP (e-ROP) study center were enrolled. The study included post hoc analysis of prospectively collected in-hospital ROP examination results among infants enrolled in the e-ROP study. We characterized infants without ROP and performed logistic regression on the subset of infants who were 27 to 33 weeks' gestational age to determine characteristics associated with the absence of ROP during all in-hospital examinations. Main Outcomes and Measures: The main measure was the absence of ROP prior to hospital discharge; the main outcome was treatment for ROP. Results: A total of 1257 infants born at 22 to 35 weeks' gestation (median [interquartile range (IQR)], 26 [25-28] weeks) with birth weights less than 1251 g (median [IQR], 860 [690-1040] g) underwent 4113 ROP examinations between 31 and 47 weeks' postmenstrual age. Overall, 1153 examinations (38%) showed no ROP, and 456 infants (36%) did not have ROP prior to study center discharge or study end point. Among infants without ROP during examinations at 32 and 33 weeks' postmenstrual age, 16 (9.4%) and 14 (5.3%) subsequently underwent ROP treatment, respectively. At hospital discharge, there was no ROP in 59% of infants of 27 to 33 weeks' gestational age, compared with 15% of those who were less than 27 weeks' gestational age (difference, 44% [95% CI, 38.5%-48.1%]; P ≤ .001). With more than 85% follow-up among infants without ROP by 37 weeks' postmenstrual age, none (95% CI, 0%-0.98%) were treated for ROP. In multivariate analysis of infants born at 27 to 33 weeks' gestation, larger birth weight (OR, 4.1 [95% CI, 1.6-10.3]) and higher gestational age (OR, 4.0 [95% CI, 1.5-10.8]) were significantly associated with absence of ROP. Conclusions and Relevance: These findings suggest that, for infants of 27 weeks' gestational age or greater and birth weights larger than 750 g, if no ROP has been detected by discharge at near-term postmenstrual age, then further ROP surveillance has limited value. Studies of all infants at risk are needed to develop more specific, objective criteria for termination of ROP surveillance and focus resources on infants at higher risk of ROP. Trial Registration: ClinicalTrials.gov Identifier: NCT01264276.

External Evaluation of Two Fluconazole Infant Population Pharmacokinetic Models.

Fluconazole is an antifungal agent used for the treatment of invasive candidiasis, a leading cause of morbidity and mortality in premature infants. Population pharmacokinetic (PK) models of fluconazole in infants have been previously published by Wade et al. (Antimicrob Agents Chemother 52:4043-4049, 2008, https://doi.org/10.1128/AAC.00569-08) and Momper et al. (Antimicrob Agents Chemother 60:5539-5545, 2016, https://doi.org/10.1128/AAC.00963-16). Here we report the results of the first external evaluation of the predictive performance of both models. We used patient-level data from both studies to externally evaluate both PK models. The predictive performance of each model was evaluated using the model prediction error (PE), mean prediction error (MPE), mean absolute prediction error (MAPE), prediction-corrected visual predictive check (pcVPC), and normalized prediction distribution errors (NPDE). The values of the parameters of each model were reestimated using both the external and merged data sets. When evaluated with the external data set, the model proposed by Wade et al. showed lower median PE, MPE, and MAPE (0.429 µg/ml, 41.9%, and 57.6%, respectively) than the model proposed by Momper et al. (2.45 µg/ml, 188%, and 195%, respectively). The values of the majority of reestimated parameters were within 20% of their respective original parameter values for all model evaluations. Our analysis determined that though both models are robust, the model proposed by Wade et al. had greater accuracy and precision than the model proposed by Momper et al., likely because it was derived from a patient population with a wider age range. This study highlights the importance of the external evaluation of infant population PK models.

Population Pharmacokinetics of Fluconazole in Premature Infants with Birth Weights Less than 750 Grams.

Fluconazole is an effective agent for prophylaxis of invasive candidiasis in premature infants. The objective of this study was to characterize the population pharmacokinetics (PK) and dosing requirements of fluconazole in infants with birth weights of <750 g. As part of a randomized clinical trial, infants born at <750 g birth weight received intravenous (i.v.) or oral fluconazole at 6 mg/kg of body weight twice weekly. Fluconazole plasma concentrations from samples obtained by either scheduled or scavenged sampling were measured using a liquid chromatography-tandem mass spectrometry assay. Population PK analysis was conducted using NONMEM 7.2. Population PK parameters were allometrically scaled by body weight. Covariates were evaluated by univariable screening followed by multivariable assessment. Fluconazole exposures were simulated in premature infants using the final PK model. A population PK model was developed from 141 infants using 604 plasma samples. Plasma fluconazole PK were best described by a one-compartment model with first-order elimination. Only serum creatinine was an independent predictor for clearance in the final model. The typical population parameter estimate for oral bioavailability in the final model was 99.5%. Scavenged samples did not bias the parameter estimates and were as informative as scheduled samples. Simulations indicated that the study dose maintained fluconazole troughs of >2,000 ng/ml in 80% of simulated infants at week 1 and 59% at week 4 of treatment. Developmental changes in fluconazole clearance are best predicted by serum creatinine in this population. A twice-weekly dose of 6 mg/kg achieves appropriate levels for prevention of invasive candidiasis in extremely premature infants.

A Comparison of Strategies for Retinopathy of Prematurity Detection.

BACKGROUND AND OBJECTIVES: Delayed detection of type 1 retinopathy of prematurity (ROP) can lead to permanent visual impairment. Providing ROP examinations is challenging because of the limited ophthalmology workforce. This study compares digital imaging-based ROP detection strategies versus serial ROP examinations. METHODS: We conducted an individual-level microsimulation study of a hypothetical cohort of 650 infants with gestational age from 23 to 30 weeks. Infants were evaluated by using strategies based on indirect ophthalmoscopy or digital imaging beginning at 32 weeks' postmenstrual age (PMA) and continuing to discharge, transfer, or 40 weeks' PMA. ROP status and the accuracy of digital imaging were based on the e-ROP (Telemedicine Approaches to Evaluating Acute-Phase ROP) study, which enrolled high-risk infants. RESULTS: Within the hypothetical NICU, the strategy of ROP examinations identified an average of 45.8 cases of type 1 ROP by discharge, transfer, or 40 weeks' PMA, and another 1.9 cases were included in the group of infants recommended to have later follow-up. Digital imaging with an ROP examination at discharge identified all 47.7 cases of type 1 ROP. On average, the ROP examination-only strategy required 1745.7 ROP examinations, whereas digital imaging with a discharge examination required 1065.5 ROP examinations and 1786.2 digital imaging sessions. CONCLUSIONS: Although digital imaging decreased the number of ROP examinations per infant, there was an increase in the total number of interventions (ie, ROP examinations and imaging sessions). Providing an ROP examination at the time of NICU discharge can significantly reduce the number of infants who require follow-up.

Safety of Retinopathy of Prematurity Examination and Imaging in Premature Infants.

OBJECTIVES: To describe adverse events (AEs) and noteworthy clinical or ocular findings associated with retinopathy of prematurity (ROP) evaluation procedures. STUDY DESIGN: Descriptive analysis of predefined AEs and noteworthy findings reported in a prospective observational cohort study of infants <1251 g birth weight who had ROP study visits consisting of both binocular indirect ophthalmoscopy (BIO) and digital retinal imaging. We compared infant characteristics during ROP visits with and without AEs. We compared respiratory support, nutrition, and number of apnea, bradycardia, or hypoxia events 12 hours before and after ROP visits. RESULTS: A total of 1257 infants, mean birth weight 802 g, had 4263 BIO and 4048 imaging sessions (total 8311 procedures). No serious AEs were related to ROP visits. Sixty-five AEs were reported among 61 infants for an AE rate of 4.9% infants (61/1257) or 0.8% total procedures (65/8311 BIO + imaging). Most AEs were due to apnea, bradycardia, and/or hypoxia (68%), tachycardia (16%), or emesis (8%). At ROP visit, infants with AEs, compared with those without, were more likely to be on mechanical ventilation (26% vs 12%, P = .04) even after adjustment for weight and postmenstrual age. Noteworthy clinical findings were reported during 8% BIO and 15% imaging examinations. Respiratory and nutrition support were not significantly different before and after ROP evaluations. CONCLUSIONS: Retinal imaging by nonphysicians combined with BIO was safe. Noteworthy clinical findings occurred during both procedures. Ventilator support was a risk factor for AEs. Monitoring rates of AEs and noteworthy findings are important to the safe implementation of ROP imaging protocols. TRIAL REGISTRATION: Clinicaltrials.gov: NCT01264276.

Fluconazole population pharmacokinetics and dosing for prevention and treatment of invasive Candidiasis in children supported with extracorporeal membrane oxygenation.

Candida infections are a leading cause of infectious disease-related death in children supported by extracorporeal membrane oxygenation (ECMO). The ECMO circuit can alter drug pharmacokinetics (PK); thus, standard fluconazole dosing may result in suboptimal drug exposures. The objective of our study was to determine the PK of fluconazole in children on ECMO. Forty children with 367 PK samples were included in the analysis. The PK data were analyzed using nonlinear mixed-effect modeling (NONMEM). A one-compartment model best described the data. Weight was included in the base model for clearance (CL) and volume of distribution (V). The final model included the effect of serum creatinine (SCR) level on CL and the effect of ECMO on V as follows: CL (in liters per hour) = 0.019 × weight × (SCR/0.4)(-0.29) × exp(ηCL) and V (in liters) = 0.93 × weight × 1.4(ECMO) × exp(ηV). The fluconazole V was increased in children supported by ECMO. Consequently, children on ECMO require a higher fluconazole loading dose for prophylaxis (12 mg/kg of body weight) and treatment (35 mg/kg) paired with standard maintenance doses to achieve exposures similar to those of children not on ECMO.

New antifungal and antiviral dosing.

Neonatal fungal and viral infections are associated with mortality and neurologic impairment among survivors. Advances in pharmacokinetics (PK) and pharmacodynamics (PD) of antimicrobial medications have led to improved dosing guidance for neonates. This article discusses the basic PK/PD properties and dosing of the most common antifungal and antiviral medications used in neonates.