Exposure Matching of Pediatric Anti-infective Drugs: Review of Drugs Submitted to the Food and Drug Administration for Pediatric Approval

PURPOSE

Over the last decade, few new antibiotics have been approved by the Food and Drug Administration (FDA) for pediatric use. For most anti-infective agents, including antibiotics, extrapolation of efficacy from adults to children is possible if the disease and therapeutic exposures are similar between the 2 populations. This approach reduces the number of studies required in children, but relies heavily on exposure matching between children and adults. Failures in exposure matching can lead to delays in pediatric approvals of new anti-infective agents. We sought to determine the extent of exposure matching, defined by a comparison of area under the concentration-time curve, between children and adults, for anti-infective drug products submitted to the FDA for approval.

METHODS

We reviewed anti-infective submissions to the FDA (2002-2014) for pediatric indication. We included drug products administered via oral, intravenous, or intramuscular administration routes, and those with AUC estimates for children in available FDA reports. Our main outcome of interest was the proportion of drugs with median (or mean) pediatric AUC within 20% of the median (or mean) reported adult value.

FINDINGS

We identified 29 drug products that met inclusion criteria, 14 (48%) of which had mean (or median) AUCs of all submitted age groups within 20% of that in adults. Only route of administration and drug class were associated with pediatric AUC within 20% of adult AUC.

IMPLICATIONS

Future research is needed to define criteria for and predictors of successful exposure matching of anti-infectives between children and adults.

Clindamycin Pharmacokinetics and Safety in Preterm and Term Infants

Clindamycin may be active against methicillin-resistant Staphylococcus aureus, a common pathogen causing sepsis in infants, but optimal dosing in this population is unknown. We performed a multicenter, prospective pharmacokinetic (PK) and safety study of clindamycin in infants. We analyzed the data using a population PK analysis approach and included samples from two additional pediatric trials. Intravenous data were collected from 62 infants (135 plasma PK samples) with postnatal ages of <121 days (median [range] gestational age of 28 weeks [23 to 42] and postnatal age of 17 days [1 to 115]). In addition to body weight, postmenstrual age (PMA) and plasma protein concentrations (albumin and alpha-1 acid glycoprotein) were found to be significantly associated with clearance and volume of distribution, respectively. Clearance reached 50% of the adult value at PMA of 39.5 weeks. Simulated PMA-based intravenous dosing regimens administered every 8 h (≤32 weeks PMA, 5 mg/kg; 32 to 40 weeks PMA, 7 mg/kg; >40 to 60 weeks PMA, 9 mg/kg) resulted in an unbound, steady-state concentration at half the dosing interval greater than a MIC for S. aureus of 0.12 μg/ml in >90% of infants. There were no adverse events related to clindamycin use. (This study has been registered at ClinicalTrials.gov under registration no. NCT01728363.).

Solithromycin Pharmacokinetics in Plasma and Dried Blood Spots and Safety in Adolescents

We assessed the pharmacokinetics and safety of solithromycin, a fluoroketolide antibiotic, in a phase 1, open-label, multicenter study of 13 adolescents with suspected or confirmed bacterial infections. On days 3 to 5, the mean (standard deviation) maximum plasma concentration and area under the concentration versus time curve from 0 to 24 h were 0.74 μg/ml (0.61 μg/ml) and 9.28 μg · h/ml (6.30 μg · h/ml), respectively. The exposure and safety in this small cohort of adolescents were comparable to those for adults. (This study has been registered at ClinicalTrials.gov under registration no. NCT01966055.).

Postnatal Cytomegalovirus Infection and the Risk for Bronchopulmonary Dysplasia

IMPORTANCE

Postnatally acquired cytomegalovirus (CMV) is typically benign in term infants but in very low-birth-weight (VLBW) infants can cause pneumonitis and sepsislike illness. Whether postnatal CMV infection results in long-term pulmonary sequelae in these infants is unknown.

OBJECTIVE

To investigate the association between postnatal CMV infection and bronchopulmonary dysplasia (BPD) and mortality in a large multicenter cohort of VLBW infants.

DESIGN, SETTING, AND PARTICIPANTS

Conducted between October 2014 and June 2015, this propensity-matched retrospective cohort study involved 101,111 hospitalized VLBW (<1500 g) infants at 348 neonatal intensive care units in the United States from 1997 to 2012. We matched infants with postnatal CMV infection 1:1 to comparison infants using propensity scores, and we used Poisson regression to examine the effect of postnatal CMV on the combined risk for death or BPD at 36 weeks' postmenstrual age. To describe features of postnatal CMV infection, we extracted clinical and laboratory data from 7 days before until 7 days after infants met criteria for postnatal CMV.

EXPOSURES

Postnatal CMV infection was defined as a diagnosis of CMV or detection of CMV from blood, urine, cerebrospinal fluid, or respiratory secretions on or after day of life 21. Infants with a CMV diagnosis or virologic detection of CMV prior to day of life 21 were not considered to have postnatal infection.

MAIN OUTCOMES AND MEASURES

The primary outcome was death or BPD at 36 weeks' postmenstrual age.

RESULTS

Of 101,111 infants, 328 (0.3%) had postnatal CMV infection. We matched a comparison infant to 303 CMV-infected infants (92%) for a final cohort of 606 infants. The median gestational age and birth weight of this cohort were 25 weeks and 730 g, respectively. Postnatal CMV infection was associated with an increased risk for death or BPD at 36 weeks' postmenstrual age (risk ratio, 1.21; 95% CI, 1.10-1.32) and BPD (risk ratio, 1.33; 95% CI, 1.19-1.50). Changes in cardiorespiratory status associated with postnatal CMV infection included a new requirement for vasopressor medications (9%; n = 29), intubation for mechanical ventilation (15%; n = 49), a new oxygen requirement (28%; n = 91), and death (1.2%; n = 4).

CONCLUSIONS AND RELEVANCE

In VLBW infants, postnatal CMV infection was associated with increased risk for BPD. Further studies are needed to determine the role of preventive measures against CMV in this population.

Burden of Invasive Staphylococcus aureus Infections in Hospitalized Infants

IMPORTANCE

Staphylococcus aureus is a frequent cause of infection in hospitalized infants. These infections are associated with increased mortality and morbidity and longer hospital stays, but data on the burden of S aureus disease in hospitalized infants are limited.

OBJECTIVES

To compare demographics and mortality of infants with invasive methicillin-resistant S aureus (MRSA) and methicillin-susceptible S aureus (MSSA), to determine the annual proportion of S aureus infections that were MRSA, and to contrast the risk of death after an invasive MRSA infection with the risk after an invasive MSSA infection.

DESIGN, SETTING, AND PARTICIPANTS

Multicenter retrospective study of a large, nationally representative cohort at 348 neonatal intensive care units managed by the Pediatrix Medical Group. Participants were 3888 infants with an invasive S aureus infection who were discharged from calendar year 1997 through calendar year 2012.

EXPOSURE

Invasive S aureus infection.

MAIN OUTCOMES AND MEASURES

The incidence of invasive S aureus infections, as well as infant characteristics and mortality after MRSA or MSSA infection.

RESULTS

The 3888 infants had 3978 invasive S aureus infections (2868 MSSA and 1110 MRSA). The incidence of invasive S aureus infection was 44.8 infections per 10,000 infants. The yearly proportion of invasive infections caused by MRSA increased from calendar year 1997 through calendar year 2006 and has moderately decreased since then. Infants with invasive MRSA or MSSA infections had similar gestational ages and birth weights. Invasive MRSA infections occurred more often at a younger postnatal age. For infants with available mortality data, more infants with invasive MSSA infections (n = 237) died before hospital discharge than infants with invasive MRSA infections (n = 110). The proportions of infants who died after invasive MSSA and MRSA infections were similar at 237 of 2474 (9.6%) and 110 of 926 (11.9%), respectively (P = .05). The adjusted risk of death before hospital discharge was similar after invasive MSSA and MRSA infections (risk ratio, 1.19; 95% CI, 0.96-1.49). The risks of death at 7 and 30 days after invasive infection were similar between infants with invasive MSSA infection and infants with invasive MRSA infection.

CONCLUSIONS AND RELEVANCE

Infant mortality after invasive MRSA and MSSA infections is similar, but MSSA causes more infections and more deaths in infants than MRSA. Measures to prevent S aureus infection should include MSSA in addition to MRSA.

Survival Benefit of Empirical Therapy for Staphylococcus aureus Bloodstream Infections in Infants

BACKGROUND

The impact of early adequate empirical antibiotic therapy on outcomes of infants in the neonatal intensive care unit (NICU) who develop Staphylococcus aureus bloodstream infections (BSI) is unknown.

METHODS

Infants with S. aureus BSI discharged in 1997-2012 from 348 NICUs managed by the Pediatrix Medical Group were identified. Early adequate empirical antibiotic therapy was defined as exposure to ≥1 antibiotic with anti-staphylococcal activity on the day the first positive blood culture was obtained. All other cases were defined as inadequate empirical antibiotic therapy. We evaluated the association between inadequate empirical antibiotic therapy on outcomes controlling for gestational age, small for gestational age status, gender, discharge year, mechanical ventilation, inotropic support and use of supplemental oxygen. The primary outcome was 30-day mortality. Secondary outcomes were 7-day mortality, death before hospital discharge and length of bacteremia.

RESULTS

Of the 3339 infants with S. aureus BSI, 2492 (75%) had methicillin-susceptible S. aureus (MSSA) BSI and 847 (25%) had methicillin-resistant S. aureus (MRSA) BSI. Inadequate empirical antibiotic therapy was administered in 725 (22%) cases. Inadequate empirical antibiotic therapy was associated with increased 30-day mortality (odds ratio: 2.03; 95% confidence interval: 1.08-3.82) among infants with MRSA BSI. Inadequate empirical antibiotic therapy was not associated with increases in mortality among infants with MSSA BSI.

CONCLUSIONS

After controlling for confounders, inadequate empirical antibiotic therapy was associated with a modestly increased mortality at 30 days for infants with MRSA BSI.

Cefepime and Ceftazidime Safety in Hospitalized Infants

BACKGROUND

Cefepime and ceftazidime are cephalosporins used for the treatment of serious Gram-negative infections. These cephalosporins are used off-label in the setting of minimal safety data for young infants.

METHODS

We identified all infants discharged from 348 neonatal intensive care units managed by the Pediatrix Medical Group between 1997 and 2012 who were exposed to either cefepime or ceftazidime in the first 120 days of life. We reported clinical and laboratory adverse events occurring in infants exposed to cefepime or ceftazidime and used multivariable logistic regression to compare the odds of seizures and death between the 2 groups.

RESULTS

A total of 1761 infants received 13,293 days of ceftazidime, and 594 infants received 4628 days of cefepime. Laboratory adverse events occurred more frequently on days of therapy with ceftazidime than with cefepime (373 vs. 341 per 1000 infant days, P < 0.001). Seizure was the most commonly observed clinical adverse event, occurring in 3% of ceftazidime-treated infants and 4% of cefepime-treated infants (P = 0.52). Mortality was similar between the ceftazidime and cefepime groups (5% vs. 3%, P = 0.07). There was no difference in the adjusted odds of seizure [odds ratio (OR) = 0.96 (95% confidence interval: 0.89-1.03)] or the combined outcome of mortality or seizures [OR = 1.00 (0.96-1.04)] in infants exposed to ceftazidime versus those exposed to cefepime.

CONCLUSIONS

In this cohort of infants, cefepime was associated with fewer laboratory adverse events than ceftazidime, although this may have been due to a significant difference in clinical exposures and severity of illness between the 2 groups. There was no difference in seizure risk or mortality between the 2 drugs.

Use and Safety of Erythromycin and Metoclopramide in Hospitalized Infants

OBJECTIVE

Prokinetic medications are used in premature infants to promote motility and decrease time to full enteral feeding. Erythromycin and metoclopramide are the most commonly used prokinetic medications in the neonatal intensive care unit (NICU), but their safety profile is not well defined.

METHODS

We conducted a large retrospective cohort study using data from 348 NICUs managed by the Pediatrix Medical Group. All of the infants exposed to ≥1 dose of erythromycin, metoclopramide, or both, from a cohort of 8,87,910 infants discharged between 1997 and 2012 were included. We collected laboratory and clinical information while infants were exposed to erythromycin or metoclopramide and described the frequency of laboratory abnormalities and clinical adverse events (AEs).

RESULTS

Metoclopramide use increased from 1997 to 2005 and decreased from 2005 to 2012, whereas erythromycin use remained stable. Erythromycin use was most often associated with a diagnosis of feeding problem (40%), whereas metoclopramide was most often associated with a diagnosis of gastroesophageal reflux (59%). The most common laboratory AE during exposure to erythromycin or metoclopramide was hyperkalemia (8.6/1000 infant days on erythromycin and 11.0/1000 infant days on metoclopramide). Incidence of pyloric stenosis was greater with erythromycin than with metoclopramide (10/1095, 0.9% vs 76/19,001, 0.4%; P = 0.01), but odds were not significantly increased after adjusting for covariates (odds ratio 0.52, 95% confidence interval [CI] 0.26-1.02, P = 0.06). More infants experienced an AE while treated with metoclopramide than with erythromycin (odds ratio 1.21, 95% CI 1.03-1.43).

CONCLUSIONS

Metoclopramide was associated with increased risk of AEs compared with erythromycin. Studies are needed to confirm safety and effectiveness of both the drugs in infants.

Gaps in Drug Dosing for Obese Children: A Systematic Review of Commonly Prescribed Emergency Care Medications

PURPOSE

Approximately 1 of 6 children in the United States is obese. This has important implications for drug dosing and safety because pharmacokinetic (PK) changes are known to occur in obesity due to altered body composition and physiologic mechanisms. Inappropriate drug dosing in an emergency setting can limit therapeutic efficacy and increase drug-related toxic effects for obese children. Few systematic reviews examining PK properties and drug dosing in obese children have been performed.

METHODS

We identified 25 emergency care drugs from the Strategic National Stockpile and Acute Care Supportive Drugs List and performed a systematic review for each drug in 3 study populations: obese children (2-18 years of age), normal weight children, and obese adults (aged >18 years). For each study population, we first reviewed a drug's Food and Drug Administration label and then performed a systematic literature review. From the literature, we extracted drug PK data, biochemical properties, and dosing information. We then reviewed data in 3 age subpopulations (2-7 years, 8-12 years, and 13-18 years) for obese and normal weight children and by route of drug administration (intramuscular, intravenous, oral, and inhaled). If sufficient PK data were not available by age and route of administration, a data gap was identified.

FINDINGS

Only 2 of 25 emergency care drugs (8%) contained dosing information on the Food and Drug Administration label for obese children and adults compared with 22 of 25 (88%) for normal weight children. We found no sufficient PK data in the literature for any of the emergency care drugs in obese children. Sufficient PK data were found for 7 of 25 emergency care drugs (28%) in normal weight children and 3 of 25 (12%) in obese adults.

IMPLICATIONS

Insufficient information exists to guide dosing in obese children for any of the emergency care drugs reviewed. This knowledge gap is alarming, given the known PK changes that occur in the setting of obesity. Future clinical trials examining the PK properties of emergency care medications in obese children should be prioritized.

Neonatal Escherichia coli Bloodstream Infections: Clinical Outcomes and Impact of Initial Antibiotic Therapy

BACKGROUND

Escherichia coli is a common cause of bloodstream infections (BSIs) in infants and is associated with high mortality and morbidity among survivors. The clinical significance of antibiotic resistance and timing of appropriate antimicrobial therapy in this population is poorly understood.

METHODS

We identified all infants with E. coli BSIs discharged from 77 neonatal intensive care units managed by the Pediatrix Medical Group in 2012. We used multivariable logistic regression to evaluate the association between 30-day mortality and ampicillin-resistant E. coli BSI, as well as the number of active empiric antimicrobial agents administered, controlling for gestational age, small-for-gestational age status, early-onset versus late-onset BSI, oxygen requirement, ventilator support and inotropic support on the day of the first positive blood culture.

RESULTS

We identified 258 episodes of E. coli BSI, including 123 (48%) ampicillin-resistant isolates. Unadjusted 30-day mortality did not significantly differ between infants with ampicillin-resistant versus ampicillin-susceptible E. coli BSI [11 of 123 (9%) vs. 7 of 135 (5%); P = 0.33; adjusted odds ratio = 1.37 (95% confidence interval: 0.39, 4.77)]. Among ampicillin-resistant E. coli BSIs, 30-day mortality was not significantly lower for infants treated with at least one empiric antimicrobial active against ampicillin-resistant E. coli versus infants receiving no active empiric agent [adjusted odds ratio = 1.50 (0.07, 33.6)].

CONCLUSIONS

In this population of infants with E. coli BSI, ampicillin resistance was not associated with significantly increased mortality. Among the subset of infants with ampicillin-resistant E. coli, appropriate empirical antibiotic therapy was not associated with lower mortality.

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.

Drug Dosing and Pharmacokinetics in Children With Obesity: A Systematic Review

IMPORTANCE

Obesity affects nearly one-sixth of US children and results in alterations to body composition and physiology that can affect drug disposition, possibly leading to therapeutic failure or toxic side effects. The depth of available literature regarding obesity's effect on drug safety, pharmacokinetics, and dosing in obese children is unknown.

OBJECTIVE

To perform a systematic literature review describing the current evidence of the effect of obesity on drug disposition in children.

EVIDENCE REVIEW

We searched the MEDLINE, Cochrane, and EMBASE databases (January 1, 1970-December 31, 2012) and included studies if they contained data on drug clearance, volume of distribution, or drug concentration in obese children (aged ≤18 years). We compared exposure and weight-normalized volume of distribution and clearance between obese and nonobese children. We explored the association between drug physicochemical properties and clearance and volume of distribution.

FINDINGS

Twenty studies met the inclusion criteria and contained pharmacokinetic data for 21 drugs. The median number of obese children studied per drug was 10 (range, 1-112) and ages ranged from newborn to 29 years (1 study described pharmacokinetics in children and adults together). Dosing schema varied and were either a fixed dose (6 [29%]) or based on body weight (10 [48%]) and body surface area (4 [19%]). Clinically significant pharmacokinetic alterations were observed in obese children for 65% (11 of 17) of the studied drugs. Pharmacokinetic alterations resulted in substantial differences in exposure between obese and nonobese children for 38% (5 of 13) of the drugs. We found no association between drug lipophilicity or Biopharmaceutical Drug Disposition Classification System class and changes in volume of distribution or clearance due to obesity.

CONCLUSIONS AND RELEVANCE

Consensus is lacking on the most appropriate weight-based dosing strategy for obese children. Prospective pharmacokinetic trials in obese children are needed to ensure therapeutic efficacy and enhance drug safety.

Rifampin use and safety in hospitalized infants

OBJECTIVE

This study aims to examine the use and safety of rifampin in the hospitalized infants.

STUDY DESIGN

Observational study of clinical and laboratory adverse events among infants exposed to rifampin from 348 neonatal intensive care units managed by the Pediatrix Medical Group between 1997 and 2012.

RESULT

Overall, 2,500 infants received 4,279 courses of rifampin; mean gestational age was 27 weeks (5th, 95th percentile; 23, 36) and mean birth weight was 1,125 g (515; 2,830). Thrombocytopenia (121/1,000 infant days) and conjugated hyperbilirubinemia (25/1,000 infant days) were the most common laboratory adverse events. The most common clinical adverse events were medical necrotizing enterocolitis (64/2,500 infants, 3%) and seizure (60/2,500 infants, 2%).

CONCLUSION

The overall incidence of adverse events among infants receiving rifampin appears low; however, additional studies to further evaluate safety and dosing of rifampin in this population are needed.

Advances in the treatment of invasive neonatal candidiasis

INTRODUCTION

Invasive candidiasis is responsible for ∼ 10% of nosocomial sepsis in very-low-birth-weight infants and is associated with substantial morbidity and mortality. Over the last two decades, the antifungal armamentarium against Candida spp. has increased; however, efficacy and safety studies in this population are lacking.

AREAS COVERED

We reviewed the medical literature and extracted information on clinical and observational studies evaluating the use of antifungal agents in neonates with invasive candidiasis.

EXPERT OPINION

Efficacy and safety data for antifungals in neonates are lacking, and the majority of studies conducted to date have concentrated on pharmacokinetic/pharmacodynamic evaluations. Unlike other anti-infective agents, efficacy data in the setting of neonatal candidiasis cannot be extrapolated from adult studies due to differences in the pathophysiology of the disease in this population relative to older children and adults. Data for amphotericin B deoxycholate, fluconazole, and micafungin suggest that these are the current agents of choice for this disease in neonates until data for newer antifungal agents become available. For prophylaxis, data from fluconazole randomized controlled trials will be submitted to the regulatory agencies for labeling. Ultimately, the field of therapeutics for neonatal candidiasis will require multidisciplinary collaboration given the numerous challenges associated with conducting clinical trials in neonates.

Association of Adverse Pregnancy Outcomes With Glyburide vs Insulin in Women With Gestational Diabetes

IMPORTANCE

Glyburide is thought to be safe for use during pregnancy for treatment of gestational diabetes mellitus (GDM). However, there are limited data on the effectiveness of glyburide when compared with insulin as used in a real-world setting.

OBJECTIVE

To estimate the risk of adverse maternal and neonatal outcomes in women with GDM treated with glyburide compared with insulin.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective cohort study of a population-based cohort from a nationwide US employer-based insurance claims database from January 1, 2000, to December 31, 2011. We identified women with GDM and their newborns. We excluded those with type 1 or 2 diabetes and those younger than 15 years or older than 45 years.

EXPOSURES

Treatment with glyburide or insulin during pregnancy within 150 days before delivery.

MAIN OUTCOMES AND MEASURES

We used binomial regression to estimate risk ratios (RRs) and risk differences with 95% confidence intervals for the association of glyburide with diagnosis codes for obstetric trauma, cesarean delivery, birth injury, preterm birth, hypoglycemia, respiratory distress, jaundice, large for gestational age, and hospitalization in the neonatal intensive care unit. Inverse probability of treatment weights were used to adjust for maternal characteristics that differed between the treatment groups.

RESULTS

Among 110,879 women with GDM, 9173 women (8.3%) were treated with glyburide (n = 4982) or insulin (n = 4191). After adjusting for differences at baseline, newborns of women treated with glyburide were at increased risk for neonatal intensive care unit admission (RR = 1.41; 95% CI, 1.23-1.62), respiratory distress (RR = 1.63; 95% CI, 1.23-2.15), hypoglycemia (RR = 1.40; 95% CI, 1.00-1.95), birth injury (RR = 1.35; 95% CI, 1.00-1.82), and large for gestational age (RR = 1.43; 95% CI, 1.16-1.76) compared with those treated with insulin; they were not at increased risk for obstetric trauma (RR = 0.92; 95% CI, 0.71-1.20), preterm birth (RR = 1.06; 95% CI, 0.93-1.21), or jaundice (RR = 0.96; 95% CI, 0.48-1.91). The risk of cesarean delivery was 3% lower in the glyburide group (adjusted RR = 0.97; 95% CI, 0.93-1.00). The risk difference associated with glyburide was 2.97% (95% CI, 1.82-4.12) for neonatal intensive care unit admission, 1.41% (95% CI, 0.61-2.20) for large for gestational age, and 1.11% (95% CI, 0.50-1.72) for respiratory distress.

CONCLUSIONS AND RELEVANCE

Newborns from privately insured mothers treated with glyburide were more likely to experience adverse outcomes than those from mothers treated with insulin. Given the widespread use of glyburide, further investigation of these differences in pregnancy outcomes is a public health priority.

No survival benefit with empirical vancomycin therapy for coagulase-negative staphylococcal bloodstream infections in infants

BACKGROUND

Coagulase-negative Staphylococcus (CoNS) is the most common cause of bloodstream infections (BSI) in hospitalized infants. CoNS BSI is most reliably treated with vancomycin; however, concerns about side effects and promoting resistance often delay empirical vancomycin therapy until culture results become available.

METHODS

All infants with CoNS BSI discharged from 348 neonatal intensive care units managed by the Pediatrix Medical Group from 1997 to 2012 were identified. Empirical vancomycin therapy was defined as vancomycin exposure on the day of the first positive blood culture. Delayed vancomycin therapy was defined as vancomycin exposure 1-3 days after the first positive blood culture. We used multivariable logistic regression with random effects for site to evaluate the association between the use of empirical vancomycin therapy versus delayed vancomycin therapy and 30-day mortality, controlling for gestational age, small-for-gestational age status, postnatal age on the day of the first positive culture, oxygen requirement, ventilator support and inotropic support on the day the first positive culture was obtained.

RESULTS

A total of 4364 infants with CoNS BSI were identified; 2848 (65%) were treated with empirical vancomycin. The median postnatal age at first positive culture was 14 days (interquartile range: 9, 21). Unadjusted 30-day mortality was similar for infants treated with empirical vancomycin and infants treated with delayed vancomycin therapy [166/2848 (6%) vs. 69/1516 (4%); P = 0.08]. There was no significant difference in 30-day mortality on multivariable analysis [odds ratio: 1.14 (0.84, 1.56)]. The median duration of bacteremia was 1 day longer for infants with delayed vancomycin therapy [4 days (interquartile range: 2, 6) vs. 3 days (2, 5); P < 0.0001].

CONCLUSIONS

The median duration of bacteremia was 1 day longer in infants with CoNS BSI who received delayed vancomycin therapy. Despite this finding, empirical vancomycin therapy for CoNS BSI was not associated with improved mortality.

The epidemiology and diagnosis of invasive candidiasis among premature infants

Invasive candidiasis is a leading infectious cause of morbidity and mortality in premature infants. Improved recognition of modifiable risk factors and antifungal prophylaxis has contributed to the recent decline in the incidence of this infection among infants. Invasive candidiasis typically occurs in the first 6 weeks of life and presents with nonspecific signs of sepsis. Definitive diagnosis relies on the growth of Candida in blood culture or cultures from other normally sterile sites, but this may identify fewer than half of cases. Improved diagnostics are needed to guide the initiation of antifungal therapy in premature infants.

Population pharmacokinetics of micafungin and its metabolites M1 and M5 in children and adolescents

The aim of this analysis was to identify therapeutic micafungin regimens for children that produce the same micafungin exposures known to be effective for the prevention and treatment of Candida infections in adults. Pediatric pharmacokinetic data from 229 patients between the ages of 4 months and <17 years were obtained from four phase I and two phase III clinical trials. Population pharmacokinetic models were used to simulate the proportion of children who had a steady-state area under the concentration-time curve at 24 hours (AUC24) of micafungin within the 10th to 90th percentile range observed in a population of adults receiving a dose of micafungin with established efficacy for invasive candidiasis (100 mg/day), i.e., 75 to 139 μg·h/ml. Simulated pediatric dosages of 0.5 to 5 mg/kg of body weight/day were explored. A two-compartment model was used that incorporated body weight as a predefined covariate for allometric scaling of the pharmacokinetic parameters. During construction of the model, aspartate aminotransferase and total bilirubin were also identified as covariates that had a significant effect on micafungin clearance. A dose of 2 mg/kg resulted in the highest proportion of children within the predefined micafungin AUC24 target range for invasive candidiasis. Cutoffs of 40 or 50 kg for weight-based dosing resulted in heavier children being appropriately dosed. Thus, dose regimens of 1, 2, and 3 mg/kg/day micafungin are appropriate for the prevention of invasive candidiasis, the treatment of invasive candidiasis, and the treatment of esophageal candidiasis, respectively, in children aged 4 months to <17 years.

Anaerobic antimicrobial therapy after necrotizing enterocolitis in VLBW infants

OBJECTIVE

To evaluate the effect of anaerobic antimicrobial therapy for necrotizing enterocolitis (NEC) on clinical outcomes in very low birth weight (≤1500 g) infants.

METHODS

We identified very low birth weight infants with NEC from 348 US NICUs from 1997 to 2012. Anaerobic antimicrobial therapy was defined by antibiotic exposure on the first day of NEC. We matched (1:1) infants exposed to anaerobic antimicrobial therapy with infants who were not exposed by using a propensity score stratified by NEC severity (medical and surgical). The primary composite outcome was in-hospital death or intestinal stricture. We assessed the relationship between anaerobic antimicrobial therapy and outcome by using a conditional logistic regression on the matched cohort.

RESULTS

A total of 1390 infants exposed to anaerobic antimicrobial therapy were matched with 1390 infants not exposed. Mean gestational age and birth weight were 27 weeks and 946 g, respectively, and were similar in both groups. We found no significant difference in the combined outcome of death or strictures, but strictures as a single outcome were more common in the anaerobic antimicrobial therapy group (odds ratio 1.73; 95% confidence interval, 1.11-2.72). Among infants with surgical NEC, mortality was less common with anaerobic antimicrobial therapy (odds ratio 0.71; 95% confidence interval, 0.52-0.95).

CONCLUSIONS

Anaerobic antimicrobial therapy was not associated with the composite outcome of death or strictures but was associated with an increase in intestinal strictures. This higher incidence of intestinal strictures may be explained by the fact that death is a competing outcome for intestinal strictures, and mortality was slightly lower in the anaerobic cohort. Infants with surgical NEC who received anaerobic antimicrobial therapy had lower mortality.

Simultaneous determination of trimethoprim and sulfamethoxazole in dried plasma and urine spots

BACKGROUND

Trimethoprim-sulfamethoxazole (TMP-SMX) is an antimicrobial drug combination commonly prescribed in children and adults. The study objectives were to validate and apply an HPLC-MS/MS method to quantify TMP-SMX in dried plasma spots (DPS) and dried urine spots (DUS), and perform a comparability analysis with liquid matrices.

RESULTS

For TMP the validated range was 100-50,000 ng/ml for DPS and 500-250,000 ng/ml for DUS; for SMX, the validated range was 1000-500,000 ng/ml for both DPS and DUS. Good agreement was noted between DPS/DUS and liquid plasma and urine samples for TMP, while only modest agreement was observed for SMX in both matrices.

CONCLUSION

A precise, accurate and reproducible method was developed to quantify TMP-SMX in DPS and DUS samples.

Neonatal candidiasis: diagnosis, prevention, and treatment

Infection with Candida species is associated with significant morbidity and mortality in infants. The incidence of Candida infection varies widely across centers, likely due to differences in practice related to modifiable risk factors such as exposure to empiric antibiotics and length of parenteral nutrition. Early diagnosis of Candida and prompt treatment with appropriate antifungal agents, such as fluconazole, amphotericin B deoxycholate, and micafungin, are critical for improved outcomes. This paper reviews the current literature relating to the prevention, diagnosis, and treatment of Candida infections in the neonatal intensive care unit.