Acyclovir is used to treat herpes infections in preterm and term infants; however, the influence of maturation on drug disposition and dosing requirements is poorly characterized in this population.
We administered intravenous acyclovir to preterm and term infants <31 days postnatal age and collected plasma samples. We performed a population pharmacokinetic analysis. The primary pharmacodynamic target was acyclovir concentration ≥3 mg/L for ≥50% of the dosing interval. The final model was simulated using infant data from a clinical database.
The analysis included 28 infants (median 30 weeks gestation). Acyclovir pharmacokinetics was described by a 1-compartment model: clearance (L/h/kg) = 0.305 × (postmenstrual age [PMA]/31.3 weeks)3.02. This equation predicts a 4.5-fold increase in clearance from 25 to 41 weeks PMA. With proposed dosing, the pharmacodynamic target was achieved in 91% of infants: 20 mg/kg every 12 hours in infants <30 weeks PMA; 20 mg/kg every 8 hours in infants 30 to <36 weeks PMA; 20 mg/kg every 6 hours in infants 36–41 weeks PMA.
Acyclovir clearance increased with infant maturation. A dosing strategy based on PMA accounted for developmental changes in acyclovir disposition to achieve the surrogate pharmacodynamic target in the majority of infants.
herpes simplex virus; preterm infants; acyclovir
To compare effectiveness of three surfactant preparations (beractant, calfactant, and poractant alpha) in premature infants for preventing three outcomes: (1) air leak syndromes; (2) death; and (3) bronchopulmonary dysplasia (BPD) or death (composite outcomes).
We conducted a comparative effectiveness study of premature infants admitted to 322 neonatal intensive care units in the U.S. from 2005–2010 who were treated with beractant, calfactant, or poractant alfa. We compared the incidence of air leak syndromes, death, and bronchopulmonary dysplasia (BPD) or death, adjusting for gestational age, antenatal steroids, discharge year, and small-for-gestational-age status.
51,282 infants received surfactant; 40% received beractant, 30% calfactant, and 30% poractant alfa. Median birth weight was 1435 g (interquartile range 966–2065); median gestational age was 30 weeks (27–33). On adjusted analysis, we observed a similar risk of air leak syndromes (calfactant vs. beractant odds ratio [OR]=1.17 [95% confidence interval: 0.95, 1.43]; calfactant vs. poractant OR=1.23 [0.98, 1.56]; beractant vs. poractant OR=1.06 [0.87, 1.29]), death (calfactant vs. beractant OR=1.14 [0.93, 1.39]; calfactant vs. poractant OR=0.98 [0.78, 1.23]; beractant vs. poractant OR=0.86 [0.72, 1.04]), and BPD or death (calfactant vs. beractant OR=1.08 [0.93, 1.26]; calfactant vs. poractant OR=1.19 [1.00, 1.41]; beractant vs. poractant OR=1.10 [0.96, 1.27]).
Beractant, calfactant, and poractant alfa demonstrated similar effectiveness in prevention of air leak syndromes, death, and BPD or death in premature infants when adjusted for site. Previously described differences in mortality between surfactants likely do not represent true differences in effectiveness but may relate to site variation in outcomes.
beractant; calfactant; poractant alfa; premature infants; respiratory distress syndrome
Necrotizing enterocolitis (NEC) is associated with significant morbidity and mortality in premature infants. We sought to identify the frequency of NEC in very-low-birth-weight infants with isolated ventricular septal defects (VSD) or atrial septal defects (ASD) using a large multicenter database.
We identified a cohort of infants with birth weight <1500 g cared for in 312 neonatal intensive care units managed by the Pediatrix Medical Group between 1997 and 2010. We examined the association between presence of an ASD or a VSD with development of NEC using logistic regression to control for small-for-gestational-age status, antenatal steroid use, antenatal antibiotic use, gestational age, sex, race, Apgar score at 5 minutes, and method of delivery.
Of the 98,523 infants who met inclusion criteria, 1,904 (1.9%) had an ASD, 1943 (2.0%) had a VSD, and 146 (0.1%) had both. The incidence of NEC was 6.2% in infants without septal defects, 9.3% in those with an ASD, 7.8% in those with a VSD, and 10.3% in infants with both an ASD and a VSD. Compared to infants without septal defects, the adjusted odds ratios for developing NEC for each group—ASD alone, VSD alone, and ASD with VSD—were 1.26 (95% confidence interval 1.06–1.49), 1.27 (1.08–1.52), and 1.80 (1.03–3.12), respectively.
The presence of an ASD or a VSD was associated with NEC in this cohort of premature infants.
necrotizing enterocolitis; atrial septal defect; ventricular septal defect
Carbapenems are commonly used in hospitalized infants despite a lack of complete safety data and associations with seizures in older children. We compared the incidence of adverse events in hospitalized infants receiving meropenem versus imipenem/cilastatin.
We conducted a retrospective cohort study of 5566 infants treated with meropenem or imipenem/cilastatin in neonatal intensive care units managed by the Pediatrix Medical Group between 1997 and 2010. Multivariable conditional logistic regression was performed to evaluate the association between carbapenem therapy and adverse events, controlling for infant factors and severity of illness.
Adverse events were more common with use of meropenem compared with imipenem/cilastatin (62.8/1000 infant days vs. 40.7/1000 infant days, P<0.001). There was no difference in seizures with meropenem vs. imipenem/cilastatin (adjusted odds ratio [OR] 0.96; 95% confidence interval 0.68, 1.32). The incidence of death, as well as the combined outcome of death or seizure, was lower with meropenem use—OR 0.68 (0.50, 0.88) and OR 0.77 (0.62, 0.95), respectively.
In this cohort of infants, meropenem was associated with more frequent but less severe adverse events when compared with imipenem/cilastatin.
meropenem; imipenem/cilastatin; adverse events; infant
Urinary tract infections (UTI) are common in the neonatal intensive care unit (NICU). Blood, urine, and cerebrospinal fluid (CSF) cultures are frequently obtained to evaluate for infection. We sought to determine the concordance between positive urine cultures and blood or CSF cultures.
Infants <121 days of age with a UTI admitted to 322 NICUs managed by the Pediatrix Medical Group from 1997–2010 were identified. UTIs were defined by isolation of a single pathogenic organism in a urine sample obtained by catheterization or suprapubic tap. The UTI was concordant if the same organism was identified in the blood or CSF within 3 days of the urine culture.
Of 5681 infants with a urine culture, 984 had 1162 UTIs. Nine hundred seventy-six UTIs (84%) had a blood culture collected within 3 days, and 127 (13%) were concordant. Of the 1162 UTIs, 77 (7%) had a CSF culture collected within 3 days, and 2 (3%) were concordant.
Collection of a urine culture in infants evaluated for late-onset sepsis is important. Concordance was observed in 13% of blood cultures and 3% of CSF cultures. These findings may be related to the initiation of empirical antimicrobial therapy before evaluation for disseminated infection or poor blood culture sensitivity.
Very low birth weight neonates (≤1500 g, VLBWs) have a high rate of infection and distinct baseline immune function compared with more mature populations. In critically ill children and adults, sepsis increases subsequent infection risk. It is unknown whether sepsis modifies the risk of subsequent infection in VLBWs.
We conducted a retrospective cohort study of VLBWs ≤32 weeks gestation at birth cared for in 312 neonatal intensive care units in the United States from 1997–2011 (n=103,376). Early-onset sepsis (EOS, culture-positive only) and late-onset sepsis (LOS, culture-positive or clinical) cases were identified. Cox proportional hazards models were used to control for clinical variables between neonates with and without EOS to determine if EOS modified risk of LOS, necrotizing enterocolitis (NEC), or death.
LOS occurred in 12,112/102,317 (11.8%) neonates without EOS and in 133/1059 (12.6%) of those with EOS. After adjustment for clinical variables, the risk of LOS was not different between neonates with or without a history of EOS (hazard ratio [HR]=0.92; 95% confidence interval [CI] 0.74, 1.16). EOS increased the risk of 120-day mortality (HR=1.78; 95% CI 1.49, 2.13).
In contrast to findings in children and adults, EOS was not associated with an increased risk of LOS in this cohort. Age-specific investigations are needed to determine if post-sepsis immunologic alterations are present.
preterm; neonate; sepsis; immunoparalysis
Daptomycin is approved for the treatment of complicated skin and skin structure infections and Staphylococcus aureus bacteremia. We sought to characterize daptomycin single-dose pharmacokinetics and tolerability in young infants.
Subjects <120 days of age with suspected systemic infections were eligible for inclusion. Each subject was given a single 6 mg/kg intravenous dose of daptomycin. An average of 4 post-dose concentrations per infant was obtained.
Data from 20 infants are presented. Median gestational age at birth and postnatal age were 32 weeks (range 23, 40) and 3 days (1, 85), respectively. The median area under the concentration curve at 24 hours, volume of distribution, total body clearance, and half-life of daptomycin were 262.4 mg*h/L (166.7, 340.2), 0.21 L/kg (0.11, 0.34), 0.021 L/hr/kg (0.016, 0.034), and 6.2 hours (3.7, 9.0), respectively. No adverse events related to daptomycin were observed, including changes in creatine phosphokinase concentrations.
Daptomycin clearance in young infants was similar to that in 2–6-year-olds and higher than that observed in adolescents and adults.
daptomycin; complicated skin and skin structure infections; Staphylococcus aureus; pharmacokinetics
To assess the impact of emperic antifungal therapy of invasive candidiasis on subsequent outcomes in premature infants.
This was a cohort study of infants ≤1000 g birth weight cared for at Neonatal Research Network sites. All infants had at least 1 positive culture for Candida. Emperic antifungal therapy was defined as receipt of a systemic antifungal on the day of or the day before the first positive culture for Candida was drawn. We created Cox proportional hazards and logistic regression models stratified on propensity score quartiles to determine the effect of emperic antifungal therapy on survival, time to clearance of infection, retinopathy of prematurity, bronchopulmonary dysplasia, end-organ damage, and neurodevelopmental impairment (NDI).
136 infants developed invasive candidiasis. The incidence of death or NDI was lower for infants who received emperic antifungal therapy (19/38, 50%) compared with those who had not (55/86, 64%; odds ratio=0.27 [95% confidence interval 0.08–0.86]). There was no significant difference between the groups for any single outcome or other combined outcomes.
Emperic antifungal therapy was associated with increased survival without NDI. A prospective randomized trial of this strategy is warranted.
Candida; neonate; mortality; neurodevelopmental impairment
Early-onset sepsis is an important cause of morbidity and mortality in neonates, and its diagnosis remains challenging. The complete blood cell count and differential have been previously evaluated as diagnostic tools for early-onset sepsis in small, single-center reports. We evaluated the diagnostic accuracy of the complete blood count and differential in early-onset sepsis in a large, multicenter population of neonates admitted to the neonatal intensive care unit.
Using a cohort of 166,092 neonates with suspected early-onset sepsis with cultures admitted to 293 neonatal intensive care units, we calculated odds ratios and receiver operating characteristic curves for complete blood cell count indices and prediction of a positive culture. We determined sensitivity, specificity, and likelihood ratios for various commonly used cut-off values from the complete blood cell count.
Low white blood cell counts, low absolute neutrophil counts, and high immature-to-total neutrophil ratios were associated with increasing odds of infection (highest odds ratios: 5.38, 6.84, and 7.97, respectively). Specificity and negative predictive values were high (73.7–99.9% and >99.8%). However, sensitivities were low (0.3–54.5%) for all complete blood cell count indices analyzed.
Low white blood cell count, absolute neutrophil count, and high immature-to-total neutrophil ratio were associated with increasing odds of infection, but no complete blood cell count-derived index possesses the sensitivity to rule out reliably early-onset sepsis in neonates.
neonatal; early-onset sepsis; blood cell count
Late-onset sepsis is an important cause of morbidity and mortality in infants. Diagnosis of late-onset sepsis can be challenging. The complete blood cell count and differential have been previously evaluated as diagnostic tools for late-onset sepsis in small, single-center reports.
We evaluated the diagnostic accuracy of the complete blood count and differential in late-onset sepsis in a large multicenter population.
Using a cohort of all infants with cultures and complete blood cell count data from a large administrative database, we calculated odds ratios for infection, as well as sensitivity, specificity, positive and negative predictive values, and likelihood ratios for various commonly used cut-off values.
High and low white blood cell counts, high absolute neutrophil counts, high immature-to-total neutrophil ratios, and low platelet counts were associated with late-onset sepsis. Associations were weaker with increasing postnatal age at the time of the culture. Specificity was highest for white blood cell counts <1000/mm3 and >50,000/mm3 (>99%). Positive likelihood ratios were highest for white blood cell counts <1000/mm3 (4.1) and platelet counts <50,000/mm3 (3.5).
No complete blood count index possessed adequate sensitivity to reliably rule out late-onset sepsis in this population.
neonatal; late-onset sepsis; blood cell count
We sought to determine if a center’s approach to care of premature infants at the youngest gestational ages (22–24 weeks’ gestation) is associated with clinical outcomes among infants of older gestational ages (25–27 weeks’ gestation).
Inborn infants of 401 to 1000 g birth weight and 22 0/7 to 27 6/7 weeks’ gestation at birth from 2002 to 2008 were enrolled into a prospectively collected database at 20 centers participating in the Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network. Markers of an aggressive approach to care for 22- to 24-week infants included use of antenatal corticosteroids, cesarean delivery, and resuscitation. The primary outcome was death before postnatal day 120 for infants of 25 to 27 weeks’ gestation. Secondary outcomes were the combined outcomes of death or a number of morbidities associated with prematurity.
Our study included 3631 infants 22 to 24 weeks’ gestation and 5227 infants 25 to 27 weeks’ gestation. Among the 22- to 24-week infants, use of antenatal corticosteroids ranged from 28% to 100%, cesarean delivery from 13% to 65%, and resuscitation from 30% to 100% by center. Centers with higher rates of antenatal corticosteroid use in 22- to 24-week infants had reduced rates of death, death or retinopathy of prematurity, death or late-onset sepsis, death or necrotizing enterocolitis, and death or neurodevelopmental impairment in 25- to 27-week infants.
This study suggests that physicians’ willingness to provide care to extremely low gestation infants as measured by frequency of use of antenatal corticosteroids is associated with improved outcomes for more-mature infants.
low-birth weight infant; NICUs; treatment; patient outcome assessment
Very-low-birth-weight (VLBW, <1500 g birth weight) infants are at high risk for both early- and late-onset sepsis. Prior studies have observed a predominance of gram-negative organisms as a cause of early-onset sepsis and gram-positive organisms as a cause of late-onset sepsis. These reports are limited to large, academic neonatal intensive care units (NICUs) and may not reflect findings in other units. The purpose of this study was to determine the risk factors for sepsis, the causative organisms, and mortality following infection in a large and diverse sample of NICUs.
We analyzed the results of all cultures obtained from VLBW infants admitted to 313 NICUs from 1997 to 2010.
Over 108,000 VLBW infants were admitted during the study period. Early-onset sepsis occurred in 1032 infants, and late-onset sepsis occurred in 12,204 infants. Gram-negative organisms were the most commonly isolated pathogens in early-onset sepsis, and gram-positive organisms were most commonly isolated in late-onset sepsis. Early- and late-onset sepsis were associated with increased risk of death controlling for other confounders (odds ratio 1.45 [95% confidence interval 1.21, 1.73], and OR 1.30 [95% CI 1.21, 1.40], respectively).
This is the largest report of sepsis in VLBW infants to date. Incidence for early-onset sepsis and late-onset sepsis has changed little over this 14-year period, and overall mortality in VLBW infants with early- and late-onset sepsis is higher than in infants with negative cultures.
early-onset sepsis; late-onset sepsis; very-low-birth-weight infants
We sought to describe the incidence, pathogen distribution, and mortality associated with blood culture-proven sepsis in young infants with congenital heart disease (CHD) admitted to a neonatal intensive care unit (NICU).
Cohort study of all blood cultures obtained from infants with CHD between 4 and 120 days of age cared for in250 NICUs managed by the Pediatrix Medical Group in the United States between 1996 and 2007.
Of 11,638 infants with CHD, 656 (6%) had 821 episodes of sepsis: a cumulative incidence of 71/1000 admissions. Gram-positive organisms were the most common cause (64%), and coagulase-negative Staphylococcus and Staphylococcus aureus were the most frequently isolated species. On multivariable regression, infants with sepsis were more likely to die compared to infants with sterile blood cultures (odds ratio [OR] = 1.53 [95% confidence interval: 1.09, 2.13]). Infants with gram-negative bacteremia and candidemia were more likely to die than infants with sterile blood cultures (OR = 2.01 [1.20, 3.37], and OR = 3.18 [1.60, 6.34], respectively).
Infants with CHD have a high incidence of culture-proven sepsis, especially with staphylococcal organisms. Gram-negative bacteremia and candidemia are strongly associated with increased mortality in this group of young infants.
infant; sepsis; infection; congenital heart disease; epidemiology; outcomes
Neonatal sepsis causes significant morbidity and mortality, especially in preterm infants. Consequently, clinicians are compelled to treat with empirical antibiotics at the first signs of suspected sepsis. Unfortunately, both broad-spectrum antibiotics and prolonged treatment with empirical antibiotics are associated with adverse outcomes including invasive candidiasis, increased antimicrobial resistance, necrotizing enterocolitis, late-onset sepsis, and death. Most common neonatal pathogens are susceptible to narrow-spectrum antibiotics. The choice of antibiotic and duration of empirical treatment are strongly associated with center-based rather than with individual patient risk factors, implying that these choices are modifiable across centers. Thus, clinicians should aim to treat with short courses of narrow-spectrum antibiotics whenever possible, choosing the appropriate antibiotics and treatment duration to balance the risks of potentially untreated sepsis against the adverse effects of treatment in infants with sterile cultures.
neonatal intensive care unit; empirical; antibiotic; sepsis; infection
In premature infants with suspected intra-abdominal infection, biomarkers for treatment response to antimicrobial therapy are lacking. Intestinal fatty acid-binding protein (I-FABP) is specific to the enterocyte and is released in response to intestinal mucosal injury. I-FABP has not been evaluated as a surrogate marker of disease response to antimicrobial therapy. We examined the relationship between metronidazole exposure and urinary I-FABP concentrations in premature infants with suspected intra-abdominal infection.
We conducted an intravenous metronidazole pharmacokinetic study, collecting ≤3 urine samples per infant for I-FABP concentration measurements. We analyzed the relationship between I-FABP concentrations and measures of metronidazole exposure and pharmacokinetics, maturational factors, and other covariates.
Twenty-six samples from 19 premature infants were obtained during metronidazole treatment. When analyzed without regard to presence of necrotic gastrointestinal disease, there were no significant associations between predictor variables and I-FABP concentrations. However, when the sample was limited to premature infants with necrotic gastrointestinal disease, an association was found between average predicted metronidazole concentration and I-FABP concentration (p=0.006).
While a predictive association between urinary I-FABP and metronidazole systemic exposure was not observed, the data suggest the potential of this endogenous biomarker to serve as a pharmacodynamic surrogate for antimicrobial treatment of serious abdominal infections in neonates and infants.
necrotizing enterocolitis; biomarkers; pharmacokinetics; premature infants; antimicrobial agents
Handoff communication is a point of vulnerability when valuable patient information can be inaccurate or omitted. In 2005 we implemented a protocol to improve the handoff process for children from the operating room to the intensive care unit after cardiac surgery. We performed a cross-sectional study of the present process to understand how users adapt a communication intervention over time. 29 handoff events were observed. Individuals required for the handoff were present at 97% of events. Content items averaged a 53% reporting rate. Some clinical information not specified in the protocol demonstrated a higher reporting rate, such as echocardiogram results (68%) and vascular access (79%). A mean of 2.3 environmental distractions per minute of communication were noted. Participant-directed adjustments in content reporting suggest that a facilitator in process improvement is user-centered innovation. Future handoff communication interventions should reduce nonessential distractions and incorporate a discussion of the anticipated patient course.
handoff; safety; communication; pediatric intensive care units; congenital heart defects; postoperative care
Coagulase-negative staphylococci (CoNS) are the most commonly isolated pathogens in the neonatal intensive care unit (NICU). CoNS infections are associated with increased morbidity including neurodevelopmental impairment.
Describe the epidemiology of CoNS infections in the NICU. Determine mortality among infants with definite, probable, or possible CoNS infections.
We performed a retrospective cohort study of all blood, urine, and cerebrospinal fluid cultures from infants <121 postnatal days.
248 NICUs managed by the Pediatrix Medical Group from 1997 to 2009.
We identified 16,629 infants with 17,624 episodes of CoNS infection: 1734 (10%) definite, 3093 (17%) probable, and 12,797 (73%) possible infections. Infants with lower gestational age and birth weight had a higher incidence of CoNS infection. Controlling for gestational age, birth weight, and 5-minute Apgar score, infants with definite, probable, or possible CoNS infection had lower mortality—OR=0.74 (95% confidence interval; 0.61, 0.89), OR= 0.68 (0.59, 0.79), and OR=0.69 (0.63, 0.76)—compared to infants with negative cultures (P<0.001). No significant difference in overall mortality was found in infants with definite CoNS infection compared to those with probable or possible CoNS infection—OR=0.93 (0.75, 1.16) and OR=0.85 (0.70, 1.03), respectively.
CoNS infection was strongly related to lower gestational age and birth weight. Infants with clinical sepsis and culture-positive CoNS infection had lower mortality rates than infants with clinical sepsis and negative blood culture results. No difference in mortality between infants diagnosed with definite, probable, or possible CoNS infection was observed.
nosocomial infection; infant; prematurity; Staphylococcus
To determine whether the daily risk of central line–associated bloodstream infections (CLABSIs) increases over the dwell time of peripherally inserted central catheters (PICCs) in high-risk neonates.
Multicenter retrospective cohort including NICU patients with a PICC inserted between January 2005 and June 2010. We calculated incidence rates and used Poisson regression models to assess the risk of developing CLABSI as a function of PICC dwell time.
A total of 4797 PICCs placed in 3967 neonates were included; 149 CLABSIs occurred over 89 946 catheter-days (incidence rate 1.66 per 1000 catheter-days). In unadjusted analysis, PICCs with a dwell time of 8 to 13 days, 14 to 22 days, and ≥23 days each had an increased risk of infection compared with PICCs in place for ≤7 days (P < .05). In adjusted analysis, the average predicted daily risk of CLABSIs after PICC insertion increased during the first 2 weeks after PICC insertion and remained elevated for the dwell time of the catheter. There was an increased risk of CLABSIs in neonates with concurrent PICCs (adjusted incidence rate ratio 2.04, 1.12–3.71). The incidence of Gram-negative CLABSIs was greater in PICCs with dwell times >50 days (incidence rate ratio 5.26, 2.40–10.66).
The risk of CLABSIs increased during the 2 weeks after PICC insertion and then remained elevated until PICC removal. Clinicians should review PICC necessity daily, optimize catheter maintenance practices, and investigate novel CLABSI prevention strategies in PICCs with prolonged dwell times.
infection; catheter-related infections; NICU; central venous catheters; peripheral venous catheterization
Background: Human milk reduces morbidities in extremely low birth weight (ELBW) infants. However, clinical instability often precludes ELBW infants from receiving early enteral feeds. This study compared clinical outcomes before and after implementing an oropharyngeal colostrum (COL) protocol in a cohort of inborn (born at our facility) ELBW infants.
Study Design: This is a retrospective cohort study of inborn ELBW infants admitted to the Duke Intensive Care Nursery from January 2007 to September 2011. In November 2010, we initiated a COL protocol for infants not enterally fed whose mothers were providing breastmilk. Infants received 0.1 mL of fresh COL to each cheek every 4 hours for 5 days beginning in the first 48 postnatal hours. We assessed demographics, diagnoses, feeding history, and mortality and for the presence of medical necrotizing enterocolitis (NEC), surgical NEC, and spontaneous perforation. Between-group comparisons were made using Fisher's exact test or Wilcoxon rank sum testing where appropriate.
Results: Of the 369 infants included, 280 (76%) were born prior to the COL protocol (Pre-COL Cohort [PCC]), and 89 (24%) were born after (COL Cohort [CC]). Mortality and the percentage of infants with surgical NEC and spontaneous perforations were statistically similar between the groups. The CC weighed an average (interquartile range) of 1,666 (1,399, 1,940) g at 36 weeks versus 1,380 (1,190, 1,650) g for the PCC (p<0.001). In a multivariable analysis with birth weight as a covariable, weight at 36 weeks was significantly greater (37 g; p<0.01).
Conclusions: Initiating oropharyngeal COL in ELBW infants in the first 2 postnatal days appears feasible and safe and may be nutritionally beneficial. Further research is needed to determine if early COL administration reduces neonatal morbidity and mortality.
Piperacillin-tazobactam is often given to infants with severe infection in spite of limited pharmacokinetics (PK) data. We evaluated piperacillin-tazobactam PK in premature and term infants of ages <61 days with suspected systemic infection. Infants received intravenous piperacillin-tazobactam (80 to 100 mg/kg of body weight every 8 h [q 8 h]) based on gestational and postnatal age. Sparse plasma samples were obtained after first and multiple doses. Drug concentrations were measured by tandem mass spectrometry. PK data were analyzed using population nonlinear mixed-effect modeling. Target attainment rates for the time unbound piperacillin concentrations remained above the MIC for 50% and 75% of the dosing interval at steady state were evaluated. Bias in population PK parameter estimates was assessed for dried blood spot (DBS) samples, and a comparability analysis was performed for DBS and plasma drug concentrations using linear regression. We obtained 128 plasma samples from 32 infants, median gestational age of 30 weeks (range, 23 to 40 weeks) and postnatal age of 8 days (range, 1 to 60). Piperacillin and tazobactam PK models included body weight (WT) and postmenstrual age (PMA) as covariates for clearance and WT for volume of distribution and were used to optimize dosing in infants. DBS drug concentrations were 50 to 60% lower than those in plasma, but when combined with plasma concentrations and a matrix effect, the data generated PK model parameters similar to those for plasma alone. With PMA-based dosing (100 mg/kg q 8 h, 80 mg/kg q 6 h, and 80 mg/kg q 4 h for PMA of ≤30, 30 to 35, and 35 to 49 weeks, respectively), 90% of simulated infants achieved the surrogate therapeutic target of time above the MIC (≤32 mg/liter) for 75% of the dosing interval.
The purpose of this study is to examine the results of repeat lumbar puncture in infants with initial positive cerebrospinal fluid (CSF) cultures in order to determine the clinical characteristics and outcomes of infants with repeat positive cultures.
Cohort study of infants with an initial positive CSF culture undergoing repeat lumbar puncture between 1997 and 2004 at 150 neonatal intensive care units managed by the Pediatrix Medical group. We compared the clinical outcomes of infants with repeat positive cultures and infants with repeat negative cultures.
We identified 118 infants with repeat CSF cultures. Of these, 26 infants had repeat positive cultures. A higher proportion with repeat positive cultures died compared to those with repeat negative cultures, 6/23 (26%) vs. 6/81 (7%), respectively (p=0.02).
Among infants with a positive CSF culture, a repeat positive CSF culture is common. The presence of a second positive culture is associated with increased mortality.
neonate; newborn; cerebrospinal fluid; infection; mortality
Limited pharmacokinetic (PK) data of metronidazole in premature infants has led to various dosing recommendations. Surrogate efficacy targets for metronidazole are ill-defined and therefore aimed to exceed minimum inhibitory concentration of organisms responsible for intra-abdominal infections.
We evaluated the PK of metronidazole using plasma and dried blood spot (DBS) samples from infants ≤32 weeks gestational age in an open-label, PK, multicenter (N=3) study using population PK modeling (NONMEM). Monte Carlo simulations (N=1000 virtual subjects) were used to evaluate the surrogate efficacy target. Metabolic ratios of parent and metabolite were calculated.
Twenty-four premature infants (111 plasma and 51 DBS samples) were enrolled: median (range) gestational age at birth 25 (23–31) weeks, postnatal age 27 (1–82) days, postmenstrual age (PMA) 31 (24–39) weeks, and weight 740 (431–1466) g. Population clearance (CL, L/h/kg) was 0.038 × (PMA/30)2.45 and volume of distribution (L/kg) of 0.93. PK parameter estimates and precision were similar between plasma and DBS samples. Metabolic ratios correlated with CL.
Simulations suggested the majority of infants in the neonatal intensive care unit (>80%) would meet the surrogate efficacy target using PMA-based dosing.
neonate; drug; pharmacokinetics; metronidazole; dried blood spots
End-tidal carbon dioxide (ETCO2) is a surrogate, noninvasive measurement of arterial carbon dioxide (PaCO2); however, its clinical applicability in the intensive care unit setting remains unclear. Available research on the relationship between ETCO2 and PaCO2 has not taken a detailed assessment of physiologic dead space into consideration. We hypothesize that ETCO2 reliably predicts PaCO2 across all levels of physiologic dead space provided that the expected ETCO2-PaCO2 gradient is considered.
Fifty-six mechanically ventilated pediatric patients (0-17 years; 19.5 ± 24.5 kg) were monitored with volumetric capnography. For every arterial blood gas obtained during routine care, ETCO2 values were collected, and Vd/Vt values calculated. The ETCO2-PaCO2 relationship was assessed by Pearson's correlation coefficients within specified ranges of Vd/Vt.
Vd/Vt was ≤ 0.4 for 125 (25%) measurements, 0.41-0.55 for 160 (32%) measurements, 0.55-0.7 for 154 (31%) measurements, and > 0.7 for 54 (11%) measurements. The correlation coefficients between ETCO2 and PaCO2 were 0.95 (mean gradient = 0.3 ± 2.1) for Vd/Vt ≤ 0.4, 0.88 (mean gradient = 5.9 ± 4.3) for Vd/Vt 0.41-0.55, 0.86 (mean gradient = 13.6 ± 5.2) for Vd/Vt 0.55-0.7, and 0.78 (mean gradient = 17.8 ± 6.7) for Vd/Vt > 0.7.
Strong correlations between ETCO2 and PaCO2 were found for all Vd/Vt ranges. The ETCO2-PaCO2 gradient increased predictably with increasing Vd/Vt.
capnography; artificial respiration; blood gas analysis; pediatric; infant; mechanical ventilation; carbon dioxide
Neonatal candidiasis is serious and often fatal. Blood culture, the standard for diagnosis, has a sensitivity of 50% or less, and isolate speciation and susceptibility takes several days. This review explores recent advances in Candida detection using various diagnostic strategies.