Antibiotics in neonatal infections: a review

Oral amoxicillin plus gentamicin regimens may be superior to the procaine-penicillin plus gentamicin regimens for treatment of young infants with possible serious bacterial infection when referral is not feasible: Pooled analysis from three trials in Africa and Asia

Background

Hospital referral and admission in many- low and middle-income countries are not feasible for many young infants with sepsis/possible serious bacterial infection (PSBI). The effectiveness of simplified antibiotic regimens when referral to a hospital was not feasible has been shown before. We analysed the pooled data from the previous trials to compare the risk of poor clinical outcome for young infants with PSBI with the two regimens containing injectable procaine penicillin and gentamicin with the oral amoxicillin plus gentamicin regimen currently recommended by the World Health Organization (WHO) when referral is not feasible.

Methods

Infant records from three individually randomised trials conducted in Africa and Asia were collated in a standard format. All trials enrolled young infants aged 0-59 days with any sign of PSBI (fever, hypothermia, stopped feeding well, movement only when stimulated, or severe chest indrawing). Eligible young infants whose caretakers refused hospital admission and consented were enrolled and randomised to a trial reference arm (arm A: procaine benzylpenicillin and gentamicin) or two experimental arms (arm B: oral amoxicillin and gentamicin or arm C: procaine benzylpenicillin and gentamicin initially, followed by oral amoxicillin). We compared the rate of poor clinical outcomes by day 15 (deaths till day 15, treatment failure by day 8, and relapse between day 9 and 15) in reference arm A with experimental arms and present risk differences with 95% confidence interval (CI), adjusted for trial.

Results

A total of 7617 young infants, randomised to arm A, arm B, or arm C in the three trials, were included in this analysis. Most were 7-59 days old (71%) and predominately males (56%). Slightly over one-fifth of young infants had more than one sign of PSBI at the time of enrolment. Severe chest indrawing (45%), fever (43%), and feeding problems (25%) were the most common signs. Overall, those who received arm B had a lower risk of poor clinical outcome compared to arm A for both per-protocol (risk difference = -2.1%, 95% CI = -3.8%, -0.4%; P = 0.016) and intention-to-treat (risk difference = -1.8%, 95% CI = -3.5%, -0.2%; P = 0.031) analyses. Those who received arm C did not have an increased risk of poor clinical outcome compared to arm A for both per-protocol (risk difference = -1.1%, 95% CI = -2.8%, 0.6%) and intention-to-treat (risk difference = -0.8%, 95% CI = -2.5%, 0.9%) analyses. Overall, those who received arm B had a lower risk of poor clinical outcome compared to the combined arms A and C for both per-protocol (risk difference = -1.6%, 95% CI = -3.5%, -0.1%; P = 0.035) and intention-to-treat (risk difference = -1.4%, 95% CI = -2.8%, -0.1%; P = 0.049) analyses.

Conclusions

Analysis of pooled individual patient-level data from three large trials in Africa and Asia showed that the WHO-recommended simplified antibiotic regimen B (oral amoxicillin and injection gentamicin) was superior to regimen A (injection procaine penicillin and injection gentamicin) and combined arms A and C (injection procaine penicillin and injection gentamicin, followed by oral amoxicillin) in terms of poor clinical outcome for the outpatient treatment of young infants with PSBI when inpatient treatment was not feasible.

Registration

AFRINEST study [9] is registered with the Australian New Zealand Clinical Trials Registry: ACTRN12610000286044. SATT Bangladesh study [10] is registered with ClinicalTrials.gov: NCT00844337. SATT Pakistan study [11] is registered at ClinicalTrials.gov: NCT01027429.

Optimal dose of cefotaxime in neonates with early-onset sepsis: A developmental pharmacokinetic model-based evaluation

Objective: The perspective of real-world study is especially relevant to newborns, enabling dosage regimen optimization and regulatory approval of medications for use in newborns. The aim of the present study was to conduct a pharmacokinetic analysis of cefotaxime and evaluate the dosage used in newborns with early-onset sepsis (EOS) using real-world data in order to support the rational use in the clinical practice.

Methods: This prospective, open-label study was performed in newborns with EOS. A developmental pharmacokinetic-pharmacodynamic model of cefotaxime in EOS patients was established based on an opportunistic sampling method. Then, clinical evaluation of cefotaxime was conducted in newborns with EOS using real-world data.

Results: A one-compartment model with first-order elimination was developed, using 101 cefotaxime concentrations derived from 51 neonates (30.1–41.3°C weeks postmenstrual age), combining current weight and postnatal age. The pharmacokinetic-pharmacodynamic target was defined as the free cefotaxime concentration above MIC during 70% of the dosing interval (70% fT > MIC), and 100% of neonates receiving the dose of 50 mg/kg, BID attained the target evaluated using the model. Additionally, only two newborns had adverse reactions possibly related to cefotaxime treatment, including diarrhea and feeding intolerance.

Conclusion: This prospective real-world study demonstrated that cefotaxime (50 mg/kg, BID) had a favorable efficacy and an accepted safety profile for neonates with EOS.

Plasma-Treated Water Affects Listeria monocytogenes Vitality and Biofilm Structure

Background: Plasma-generated compounds (PGCs) such as plasma-processed air (PPA) or plasma-treated water (PTW) offer an increasingly important alternative for the control of microorganisms in hard-to-reach areas found in several industrial applications including the food industry. To this end, we studied the antimicrobial capacity of PTW on the vitality and biofilm formation of Listeria monocytogenes, a common foodborne pathogen. Results: Using a microwave plasma (MidiPLexc), 10 ml of deionized water was treated for 100, 300, and 900 s (pre-treatment time), after which the bacterial biofilm was exposed to the PTW for 1, 3, and 5 min (post-treatment time) for each pre-treatment time, separately. Colony-forming units (CFU) were significantly reduced by 4.7 log10 ± 0.29 log10, as well as the metabolic activity decreased by 47.9 ± 9.47% and the cell vitality by 69.5 ± 2.1%, compared to the control biofilms. LIVE/DEAD staining and fluorescence microscopy showed a positive correlation between treatment and incubation times, as well as reduction in vitality. Atomic force microscopy (AFM) indicated changes in the structure quality of the bacterial biofilm. Conclusion: These results indicate a promising antimicrobial impact of plasma-treated water on Listeria monocytogenes, which may lead to more targeted applications of plasma decontamination in the food industry in the future.

Infection control and other stewardship strategies in late onset sepsis, necrotizing enterocolitis, and localized infection in the neonatal intensive care unit

Suspected or proven late onset sepsis, necrotizing enterocolitis, urinary tract infections, and ventilator associated pneumonia occurring after the first postnatal days contribute significantly to the total antibiotic exposures in neonatal intensive care units. The variability in definitions and diagnostic criteria in these conditions lead to unnecessary antibiotic use. The length of treatment and choice of antimicrobial agents for presumed and proven episodes also vary among centers due to a lack of supportive evidence and guidelines. Implementation of robust antibiotic stewardship programs can encourage compliance with appropriate dosages and narrow-spectrum regimens.

Early Bacterial Colonization and Antibiotic Resistance Gene Acquisition in Newborns

Several studies have recently identified the main factors contributing to the bacterial colonization of newborns and the dynamics of the infant microbiome development. However, most of these studies address large time periods of weeks or months after birth, thereby missing on important aspects of the early microbiome maturation, such as the acquisition of antibiotic resistance determinants during postpartum hospitalization. The pioneer bacterial colonization and the extent of its associated antibiotic resistance gene (ARG) dissemination during this early phase of life are largely unknown. Studies addressing resistant bacteria or ARGs in neonates often focus only on the presence of particular bacteria or genes from a specific group of antibiotics. In the present study, we investigated the gut-, the oral-, and the skin-microbiota of neonates within the first 72 h after birth using 16S rDNA sequencing approaches. In addition, we screened the neonates and their mothers for the presence of 20 different ARGs by directed TaqMan qPCR assays. The taxonomic analysis of the newborn samples revealed an important shift of the microbiota during the first 72 h after birth, showing a clear site-specific colonization pattern in this very early time frame. Moreover, we report a substantial acquisition of ARGs during postpartum hospitalization, with a very high incidence of macrolide resistance determinants and mecA detection across different body sites of the newborns. This study highlights the importance of antibiotic resistance determinant dissemination in neonates during hospitalization, and the need to investigate the implication of the mothers and the hospital environment as potential sources of ARGs.

Evaluation of a System-Specific Function To Describe the Pharmacokinetics of Benzylpenicillin in Term Neonates Undergoing Moderate Hypothermia

The pharmacokinetic (PK) properties of intravenous (i.v.) benzylpenicillin in term neonates undergoing moderate hypothermia after perinatal asphyxia were evaluated, as they have been unknown until now. A system-specific modeling approach was applied, in which our recently developed covariate model describing developmental and temperature-induced changes in amoxicillin clearance (CL) in the same patient study population was incorporated into a population PK model of benzylpenicillin with a priori birthweight (BW)-based allometric scaling. Pediatric population covariate models describing the developmental changes in drug elimination may constitute system-specific information and may therefore be incorporated into PK models of drugs cleared through the same pathway. The performance of this system-specific model was compared to that of a reference model. Furthermore, Monte-Carlo simulations were performed to evaluate the optimal dose. The system-specific model performed as well as the reference model. Significant correlations were found between CL and postnatal age (PNA), gestational age (GA), body temperature (TEMP), urine output (UO; system-specific model), and multiorgan failure (reference model). For a typical patient with a GA of 40 weeks, BW of 3,000 g, PNA of 2 days (TEMP, 33.5°C), and normal UO (2 ml/kg/h), benzylpenicillin CL was 0.48 liter/h (interindividual variability [IIV] of 49%) and the volume of distribution of the central compartment was 0.62 liter/kg (IIV of 53%) in the system-specific model. Based on simulations, we advise a benzylpenicillin i.v. dose regimen of 75,000 IU/kg/day every 8 h (q8h), 150,000 IU/kg/day q8h, and 200,000 IU/kg/day q6h for patients with GAs of 36 to 37 weeks, 38 to 41 weeks, and ≥42 weeks, respectively. The system-specific model may be used for other drugs cleared through the same pathway accelerating model development.

A Population and Developmental Pharmacokinetic Analysis To Evaluate and Optimize Cefotaxime Dosing Regimen in Neonates and Young Infants

Cefotaxime is one of the most frequently prescribed antibiotics for the treatment of Gram-negative bacterial sepsis in neonates. However, the dosing regimens routinely used in clinical practice vary considerably. The objective of the present study was to conduct a population pharmacokinetic study of cefotaxime in neonates and young infants in order to evaluate and optimize the dosing regimen. An opportunistic sampling strategy combined with population pharmacokinetic analysis using NONMEM software was performed. Cefotaxime concentrations were measured by high-performance liquid chromatography-tandem mass spectrometry. Developmental pharmacokinetics-pharmacodynamics, the microbiological pathogens, and safety aspects were taken into account to optimize the dose. The pharmacokinetic data from 100 neonates (gestational age [GA] range, 23 to 42 weeks) were modeled with an allometric two-compartment model with first-order elimination. The median values for clearance and the volume of distribution at steady state were 0.12 liter/h/kg of body weight and 0.64 liter/kg, respectively. The covariate analysis showed that current weight, GA, and postnatal age (PNA) had significant impacts on cefotaxime pharmacokinetics. Monte Carlo simulations demonstrated that the current dose recommendations underdosed older newborns. A model-based dosing regimen of 50 mg/kg twice a day to four times a day, according to GA and PNA, was established. The associated risk of overdose for the proposed dosing regimen was 0.01%. We determined the population pharmacokinetics of cefotaxime and established a model-based dosing regimen to optimize treatment for neonates and young infants.

[Effects of antibiotic stewardship on neonatal bloodstream infections]

OBJECTIVE

To investigate the effects of antibiotic stewardship on the pathogen and clinical outcome of neonatal bloodstream infections (BSIs).

METHODS

A retrospective study was performed on neonates with BSIs who were admitted to the neonatal ward in the years of 2010 (pre-stewardship) and 2013 (post-stewardship) for pathogens, antibiotic resistance, antibiotic use, and clinical outcomes.

RESULTS

The admission rate of BSIs (6.47% vs 2.78%) and the incidence of nosocomial BSIs (0.70% vs 0.30%) in 2013 were significantly higher than in 2010 (P<0.01). However, there were no signicant differences in the clinical outcomes between the years of 2010 and 2013 (P>0.05). The four most common pathogens isolated from blood cultures, Staphylococcus haemolyticus, Staphylococcus epidermidis, Klebsiella pneumoniae ssp pneumoniae and E.coli, were similar between the two years. There were no significant differences in the detection rates of extended spectrum β-lactamase-positve Klebsiella pneumoniae ssp pneumoniae or E.coli between the two years. The detection rates of methicillin-resistant Staphylococcus/β-lactamase-positive Staphylococcus haemolyticus and Staphylococcus epidermidis were similar between the two years (P>0.05).

CONCLUSIONS

Since the implementation of antibiotic stewardship, there has been no marked variation in the common pathogens and their antibacterial resistance in neonatal BSIs. The antibiotic stewardship could promote the recovery of patients with BSIs.

Antimicrobial dressings for the prevention of catheter-related infections in newborn infants with central venous catheters

BACKGROUND

Central venous catheters (CVCs) provide secured venous access in neonates. Antimicrobial dressings applied over the CVC sites have been proposed to reduce catheter-related blood stream infection (CRBSI) by decreasing colonisation. However, there may be concerns on the local and systemic adverse effects of these dressings in neonates.

OBJECTIVES

We assessed the effectiveness and safety of antimicrobial (antiseptic or antibiotic) dressings in reducing CVC-related infections in newborn infants. Had there been relevant data, we would have evaluated the effects of antimicrobial dressings in different subgroups, including infants who received different types of CVCs, infants who required CVC for different durations, infants with CVCs with and without other antimicrobial modifications, and infants who received an antimicrobial dressing with and without a clearly defined co-intervention.

SEARCH METHODS

We used the standard search strategy of the Cochrane Neonatal Review Group (CNRG). We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library 2015, Issue 9), MEDLINE (PubMed), EMBASE (EBCHOST), CINAHL and references cited in our short-listed articles using keywords and MeSH headings, up to September 2015.

SELECTION CRITERIA

We included randomised controlled trials that compared an antimicrobial CVC dressing against no dressing or another dressing in newborn infants.

DATA COLLECTION AND ANALYSIS

We extracted data using the standard methods of the CNRG. Two review authors independently assessed the eligibility and risk of bias of the retrieved records. We expressed our results using risk difference (RD) and risk ratio (RR) with 95% confidence intervals (CIs).

MAIN RESULTS

Out of 173 articles screened, three studies were included. There were two comparisons: chlorhexidine dressing following alcohol cleansing versus polyurethane dressing following povidone-iodine cleansing (one study); and silver-alginate patch versus control (two studies). A total of 855 infants from level III neonatal intensive care units (NICUs) were evaluated, 705 of whom were from a single study. All studies were at high risk of bias for blinding of care personnel or unclear risk of bias for blinding of outcome assessors. There was moderate-quality evidence for all major outcomes.The single study comparing chlorhexidine dressing/alcohol cleansing against polyurethane dressing/povidone-iodine cleansing showed no significant difference in the risk of CRBSI (RR 1.18, 95% CI 0.53 to 2.65; RD 0.01, 95% CI -0.02 to 0.03; 655 infants, moderate-quality evidence) and sepsis without a source (RR 1.06, 95% CI 0.75 to 1.52; RD 0.01, 95% CI -0.04 to 0.06; 705 infants, moderate-quality evidence). There was a significant reduction in the risk of catheter colonisation favouring chlorhexidine dressing/alcohol cleansing group (RR 0.62, 95% CI 0.45 to 0.86; RD -0.09, 95% CI -0.15 to -0.03; number needed to treat for an additional beneficial outcome (NNTB) 11, 95% CI 7 to 33; 655 infants, moderate-quality evidence). However, infants in the chlorhexidine dressing/alcohol cleansing group were significantly more likely to develop contact dermatitis, with 19 infants in the chlorhexidine dressing/alcohol cleansing group having developed contact dermatitis compared to none in the polyurethane dressing/povidone-iodine cleansing group (RR 43.06, 95% CI 2.61 to 710.44; RD 0.06, 95% CI 0.03 to 0.08; number needed to treat for an additional harmful outcome (NNTH) 17, 95% CI 13 to 33; 705 infants, moderate-quality evidence). The roles of chlorhexidine dressing in the outcomes reported were unclear, as the two assigned groups received different co-interventions in the form of different skin cleansing agents prior to catheter insertion and during each dressing change.In the other comparison, silver-alginate patch versus control, the data for CRBSI were analysed separately in two subgroups as the two included studies reported the outcome using different denominators: one using infants and another using catheters. There were no significant differences between infants who received silver-alginate patch against infants who received standard line dressing in CRBSI, whether expressed as the number of infants (RR 0.50, 95% CI 0.14 to 1.78; RD -0.12, 95% CI -0.33 to 0.09; 1 study, 50 participants, moderate-quality evidence) or as the number of catheters (RR 0.72, 95% CI 0.27 to 1.89; RD -0.05, 95% CI -0.20 to 0.10; 1 study, 118 participants, moderate-quality evidence). There was also no significant difference between the two groups in mortality (RR 0.55, 95% CI 0.15 to 2.05; RD -0.04, 95% CI -0.13 to 0.05; two studies, 150 infants, I² = 0%, moderate-quality evidence). No adverse skin reaction was recorded in either group.

AUTHORS' CONCLUSIONS

Based on moderate-quality evidence, chlorhexidine dressing/alcohol skin cleansing reduced catheter colonisation, but made no significant difference in major outcomes like sepsis and CRBSI compared to polyurethane dressing/povidone-iodine cleansing. Chlorhexidine dressing/alcohol cleansing posed a substantial risk of contact dermatitis in preterm infants, although it was unclear whether this was contributed mainly by the dressing material or the cleansing agent. While silver-alginate patch appeared safe, evidence is still insufficient for a recommendation in practice. Future research that evaluates antimicrobial dressing should ensure blinding of caregivers and outcome assessors and ensure that all participants receive the same co-interventions, such as the skin cleansing agent. Major outcomes like sepsis, CRBSI and mortality should be assessed in infants of different gestation and birth weight.

Treating disorders of the neonatal central nervous system: pharmacokinetic and pharmacodynamic considerations with a focus on antiepileptics

A major consideration in the treatment of neonatal disorders is that the selected drug, dose and dosage frequency is safe, effective and appropriate for the intended patient population. Thus, a thorough knowledge of the pharmacokinetics and pharmacodynamics of the chosen drug within the patient population is essential. In paediatric and neonatal populations two additional challenges can often complicate drug treatment - the inherently greater physiological variability, and a lack of robust clinical evidence of therapeutic range. There has traditionally been an overreliance in paediatric medicine on extrapolating doses from adult values by adjusting for bodyweight or body surface area, but many other sources of variability exist which complicate the choice of dose in neonates. The lack of reliable drug dosage data in neonates has been highlighted by regulatory authorities, as only ~50% of the most commonly used paediatric medicines have been examined in a paediatric population. Moreover, there is a paucity of information on the pharmacokinetic parameters which affect drug concentrations in different body tissues, and pharmacodynamic responses to drugs in the neonate. Thus, in the present review, we draw attention to the main pharmacokinetic factors that influence the unbound brain concentration of neuroactive drugs. Moreover, the pharmacodynamic differences between neonates and adults that affect the activity of centrally-acting therapeutic agents are briefly examined, with a particular emphasis on antiepileptic drugs.

Inadequate vancomycin therapy in term and preterm neonates: a retrospective analysis of trough serum concentrations in relation to minimal inhibitory concentrations

Background

Vancomycin is effective against gram-positive bacteria and the first-line antibiotic for treatment of proven coagulase-negative staphylococcal infections. The aim of this study is bipartite: first, to assess the percentage of therapeutic initial trough serum concentrations and second, to evaluate the adequacy of the therapeutic range in interrelationship with the observed MIC-values in neonates.

Methods

In this study, preterm and term neonates admitted at a tertiary NICU in the Netherlands from January 2009 to December 2012 and treated with vancomycin for a proven gram-positive infection were included. Trough serum concentrations were measured prior to administration of the 5th dose. Trough concentrations in the range of 10 to 15 mg/L were considered therapeutic. Staphylococcal species minimal inhibitory concentrations (MIC’s) were determined using the E-test method. Species identification was performed by matrix-assisted laser desorption/ionisation mass spectrometry.

Results

Of the 112 neonates, 53 neonates (47%) had sub-therapeutic initial trough serum concentrations of vancomycin, whereas 22% had supra-therapeutic initial trough serum concentrations. In all patients doses were adjusted on basis of the initial trough concentration. In 40% (23/57) of the neonates the second trough concentration remained sub-therapeutic. MIC’s were determined for 30 coagulase-negative Staphylococcus isolates obtained from 19 patients. Only 4 out of 19 subjects had a trough concentration greater than tenfold the MIC.

Conclusions

Forty-seven percent of the neonates had sub-therapeutic initial trough serum concentrations of vancomycin. The MIC-data indicate that the percentages of underdosed patients may be greater. It may be advisable to increase the lower limit of the therapeutic range for European neonates.

Simplified regimens for management of neonates and young infants with severe infection when hospital admission is not possible: study protocol for a randomized, open-label equivalence trial

BACKGROUND

In resource-limited settings, most young infants with signs of severe infection do not receive the recommended inpatient treatment with intravenous broad spectrum antibiotics for 10 days or more because such treatment is not accessible, acceptable or affordable to families. This trial was initiated in the Democratic Republic of Congo, Kenya and Nigeria to assess the safety and efficacy of simplified treatment regimens for the young infants with signs of severe infection who cannot receive hospital care.

METHODS

This is a randomized, open-label equivalence trial in which 3600 young infants with signs of clinical severe infection will be enrolled. The primary outcome is treatment failure in 7 days after enrollment, which includes death or worsening of the clinical condition on any day, or no improvement in the clinical condition by day 4 of treatment. Secondary outcomes include compliance with study therapy, adverse effects due to the study drugs and relapse or death during the week after completion of treatment.

DISCUSSION

The results of this study, along with ongoing studies in Pakistan and Bangladesh, will inform the development of global policy for treatment of severe neonatal infections in resource-limited settings.

Scientific rationale for study design of community-based simplified antibiotic therapy trials in newborns and young infants with clinically diagnosed severe infections or fast breathing in South Asia and sub-Saharan Africa

BACKGROUND

Newborns and young infants suffer high rates of infections in South Asia and sub-Saharan Africa. Timely access to appropriate antibiotic therapy is essential for reducing mortality. In an effort to develop community case management guidelines for young infants, 0-59 days old, with clinically diagnosed severe infections, or with fast breathing, 4 trials of simplified antibiotic therapy delivered in primary care clinics (Pakistan, Democratic Republic of Congo, Kenya and Nigeria) or at home (Bangladesh and Nigeria) are being conducted.

METHODS

This article describes the scientific rationale for these trials, which share major elements of trial design. All the trials are in settings of high neonatal mortality, where hospitalization is not feasible or frequently refused. All use procaine penicillin and gentamicin intramuscular injections for 7 days as reference therapy and compare this to various experimental arms utilizing comparatively simpler combination regimens with fewer injections and oral amoxicillin.

CONCLUSION

The results of these trials will inform World Health Organization policy regarding community case management of young infants with clinical severe infections or with fast breathing.

RT-PCR detection of respiratory pathogens in newborn children admitted to a neonatal medium care unit

BACKGROUND

This study aimed to determine the prevalence of respiratory pathogens among newborns admitted to a neonatal medium care unit (NMCU) and to identify clinical predictors.

METHODS

A 1-y observational study was performed of neonates admitted to an NMCU in Amsterdam, The Netherlands. Nasopharyngeal samples were collected for the detection of respiratory viruses and bacteria by real-time PCR (RT-PCR). Cycle threshold (Ct) values were provided to estimate viral load. Predictors for the presence of study pathogens were identified.

RESULTS

From October 2010 through September 2011, 334 neonates (median age 1.3 d, 53.6% male) were included. Overall, 37 respiratory pathogens were detected in 34 children (10.2%): parainfluenza-1 (n = 9), human rhinovirus (n = 7), parainfluenza-3 (n = 6), respiratory syncytial virus (RSV, n = 6), Streptococcus pneumoniae (n = 3), adenovirus (n = 2), human coronavirus (n = 2), influenza A (n = 1), and bocavirus (n = 1). Neonates with higher viral loads (Ct <35; n = 11) were more often clinically ill than those with lower viral loads (Ct ≥35; n = 23). Two variables significantly contributed to the detection of study pathogens: age (odds ratio (OR) 1.21 for each day older; 95% confidence interval 1.12-1.30) and rhinorrhea (OR 6.71; 95% confidence interval 1.54-29.21).

CONCLUSION

Respiratory pathogens seem to play a role in neonates admitted to an NMCU. The influence of respiratory pathogen detection on clinical management remains to be determined.

Infections of the nervous system

Glycemic control is an important aspect of patient care in the surgical Infections of the nervous system are among the most difficult infections in terms of the morbidity and mortality posed to patients, and thereby require urgent and accurate diagnosis. Although viral meningitides are more common, it is the bacterial meningitides that have the potential to cause a rapidly deteriorating condition that the physician should be familiar with. Viral encephalitis frequently accompanies viral meningitis, and can produce focal neurologic findings and cognitive difficulties that can mimic other neurologic disorders. Brain abscesses also have the potential to mimic and present like other neurologic disorders, and cause more focal deficits. Finally, other infectious diseases of the central nervous system, such as prion disease and cavernous sinus thrombosis, are explored in this review.

Cefotaxime-induced near-fatal anaphylaxis in a neonate: A case report and review of literature

A case of 7-day-old male neonate with cefotaxime-induced near-fatal anaphylaxis is being reported. Child was started on intravenous cefotaxime on day 3 of life in view of early-onset sepsis with pneumonia, following which there was clinical improvement. Child was then shifted out of intensive care to general ward for completion of antibiotic course. One day prior to the planned discharge, child suddenly developed poor sensorium, flaccidity, apnea, and cyanosis within seconds of receiving intravenous cefotaxime and was found to have bradypnea with bradycardia. Prompt resuscitation was carried out with artificial ventilation, adrenaline, and steroids. Spontaneous breathing reappeared and the clinical condition improved.

Systematic review: neonatal meningitis in the developing world

Meningitis is more common in the neonatal period than any other time in life and is an important cause of morbidity and mortality globally. Despite the majority of the burden occurring in the developing world, the majority of the existing literature originates from wealthy countries. Mortality from neonatal meningitis in developing countries is estimated to be 40-58%, against 10% in developed countries. Important differences exist in the spectrum of pathogens isolated from cerebrospinal fluid cultures in developed versus developing countries. Briefly, while studies in developed countries have generally found Group B streptococcus (GBS), Escherichia coli and Listeria monocytogenes as important organisms, we describe how in the developing world results have varied; particularly regarding GBS, other Gram negatives (excluding E. coli), Listeria and Gram-positive organisms. The choice of empiric antibiotics should take into consideration local epidemiology if known, early versus late disease, resistance patterns and availability within resource constraints. Gaps in knowledge, the role of adjuvant therapies and future directions for research are explored.

Pharmacokinetics of cefotaxime and desacetylcefotaxime in infants during extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation (ECMO) is used to temporarily sustain cardiac and respiratory function in critically ill infants but can cause pharmacokinetic changes necessitating dose modifications. Cefotaxime (CTX) is used to prevent and treat infections during ECMO, but the current dose regimen is based on pharmacokinetic data obtained for non-ECMO patients. The objective of this study was to validate the standard dose regimen of 50 mg/kg of body weight twice a day (postnatal age [PNA], <1 week), 50 mg/kg three times a day (PNA, 1 to 4 weeks), or 37.5 mg/kg four times a day (PNA, >4 weeks). We included 37 neonates on ECMO, with a median (range) PNA of 3.3 (0.67 to 199) days and a median (range) body weight of 3.5 (2.0 to 6.2) kg at the onset of ECMO. Median (range) ECMO duration was 108 (16 to 374) h. Plasma samples were taken during routine care, and pharmacokinetic analysis of CTX and its active metabolite, desacetylcefotaxime (DACT), was done using nonlinear mixed-effects modeling (NONMEM). A one-compartment pharmacokinetic model for CTX and DACT adequately described the data. During ECMO, CTX clearance (CL(CTX)) was 0.36 liter/h (range, 0.19 to 0.75 liter/h), the volume of distribution of CTX (V(CTX)) was 1.82 liters (0.73 to 3.02 liters), CL(DACT) was 1.46 liters/h (0.48 to 5.93 liters/h), and V(DACT) was 11.0 liters (2.32 to 28.0 liters). Elimination half-lives for CTX and DACT were 3.5 h (1.6 to 6.8 h) and 5.4 h (0.8 to 14 h). Peak CTX concentration was 98.0 mg/liter (33.2 to 286 mg/liter). DACT concentration varied between 0 and 38.2 mg/liter, with a median of 10 mg/liter in the first 12 h postdose. Overall, CTX concentrations were above the MIC of 8 mg/liter over the entire dose interval. Only 1 of the 37 patients had a sub-MIC concentration for over 50% of the dose interval. In conclusion, the standard cefotaxime dose regimen provides sufficiently long periods of supra-MIC concentrations to provide adequate treatment of infants on ECMO.

Therapeutic drug monitoring of aminoglycosides in neonates

The efficacy and toxicity of aminoglycosides show a strong direct positive relationship with blood drug concentrations, therefore, therapy with aminoglycosides in adults is usually guided by therapeutic drug monitoring. Dosing regimens in adults have evolved from multiple daily dosing to extended-interval dosing. This evolution has also taken place in neonates. Neonates, however, display large interindividual differences in the pharmacokinetics of aminoglycosides due to developmental differences early in life. The volume of distribution of aminoglycosides shows a strong relationship with bodyweight, which tends to be larger (corrected for bodyweight) in more premature infants and those with sepsis. Renal clearance of aminoglycosides increases with gestational age and accelerates immediately after birth. Because of these developmental influences, there is great inter- and intraindividual variability in the volume of distribution and clearance of these drugs, and investigators have established aminoglycoside dosing regimens based on bodyweight and/or gestational age. Widely practised dosing regimens comprise 4-5 mg/kg bodyweight of gentamicin every 24-48 hours as a first dose, followed by dose adjustment based on therapeutic drug monitoring. Although formal toxicity studies are scarce, there is no evidence that aminoglycoside toxicity in neonates differs from that in adults. Monitoring of blood drug concentrations and intelligent reconstruction of individual pharmacokinetic behaviour using a population pharmacokinetic model, optimally chosen blood sampling times and appropriate pharmacokinetic software, help clinicians to quickly optimize aminoglycoside dosing regimens to maximize the clinical effect and minimize the toxicity of these drugs.

Evaluating and managing neonatal acute renal failure in a resource-poor setting

Acute renal failure (ARF) is encountered in neonatal care where it may be associated with significant morbidities. Pre-renal failure, which is due to impaired renal tissue perfusion, is the commonest type of ARF. It is amenable to treatment with excellent prognosis following prompt diagnosis and timely institution of appropriate intervention. Unfortunately, ARF in the newborn is usually asymptomatic and it is only suspected when a newborn infant has not been observed to pass urine over several hours or when serum Creatinine is observed to be elevated or rising. In resource-poor settings, it is often difficult to conduct detailed evaluation of suspected cases of newborn ARF due to lack of appropriate equipments and infrastructure. Similarly, therapeutic facilities are sparse and there is heavy reliance on conservative management of cases. Such difficulties encountered in the evaluation and management of newborns with ARF in most parts of the developing world, like Nigeria, where diagnostic and therapeutic facilities are limited are highlighted.

Clinical microbiology of early-onset and late-onset neonatal sepsis, particularly among preterm babies

Prematurity has got special challenge for clinicians and also other medical staff, such as microbiologists. Immature host defense mechanisms support early-onset sepsis, which can be very serious with very high mortality. While the past decade has been marked by a significant decline in early-onset group B streptococcal (GBS) sepsis in both term and preterm neonates, the overall incidence of early-onset sepsis has not decreased in many centers, and several studies have found an increase in sepsis due to gram-negative organisms. With increasing survival of these more fastidious preterm infants, late-onset sepsis or specially nosocomial bloodstream infection (BSI) will continue to be a challenging complication that affects other morbidities, length of hospitalization, cost of care, and mortality rates. Especially the very low birthweight (VLBW) infants sensitive to serious systemic infection during their initial hospital stay. Sepsis caused by multiresistant organisms and Candida spp. are also increasing in incidence, has become the most common cause of death among preterm infants. This review focuses on the clinical microbiology of neonatal sepsis, particularly among preterm babies, summarizing the most frequent bacterial and fungal organisms causing perinatally acquired and also nosocomial sepsis.

Parenteral antibiotics for the treatment of serious neonatal bacterial infections in developing country settings

BACKGROUND

A number of special issues must be considered when selecting simple, safe, inexpensive, and effective antimicrobial regimens for treatment of neonatal sepsis in developing country community settings.

METHODS

We reviewed available data regarding pharmacologic profiles of parenteral antibiotics with specific attention to properties relevant to their use in the treatment of neonatal infections in developing country communities.

RESULTS

For community-based management of neonatal infections, particularly attractive properties include efficacy and safety of extended-interval, intramuscular dosing regimens. The penicillins and cephalosporins have relatively favorable efficacy and safety profiles. Although the aminoglycosides have narrow therapeutic indices, when used appropriately, they are safe and effective. Although inexpensive and effective, the potential for significant life-threatening toxicity among neonates associated with chloramphenicol makes it the least preferred of the parenteral agents for empiric therapy.

CONCLUSIONS

The preferred parenteral regimens for community and first-level facility use are a combination of procaine penicillin G and gentamicin, or ceftriaxone given alone, which are safe and retain efficacy when dosed at extended intervals (> or =24 hours) by intramuscular administration.

Maternal Intrapartum Antibiotic Use and Severity of Neonatal Infection in Qatar: A hospital-based cohort study

To study the effect of intrapartum antibiotics on neonatal mortality and morbidity for infants with cultureproven neonatal sepsis the records were reviewed of all live born infants with culture positive neonatal septicemia admitted to the Neonatal Intensive Care Unit (NICU), Women's Hospital, Qatar between January 1st 2004 and April 30th 2005. Of 113 infants with culture-proven septicemia, 59 had received intrapartum antibiotics. Using univariate analysis, infants whose mothers had received intrapartum antibiotics were less likely to survive the septic episode (OR 0.09,95% CL 0.11-0.75, p = 0.009) and more likely to have severe septicemia (OR 4.38, 95% CI 1.74-11.02, p = 0.01) but gestational age adjusted estimates of survival and severe sepsis showed no difference between study and comparison groups. Being retrospective the study had certain limitations in variables but there is no clear evidence that intrapartum use of antibiotics plays a direct role in increasing mortality in septicemic infants.

N-acetylcysteine as a potential antidote and biomonitoring agent of methylmercury exposure

BACKGROUND

Many people, by means of consumption of seafood or other anthropogenic sources, are exposed to levels of methylmercury (MeHg) that are generally considered to be quite low, but that may nevertheless produce irreversible brain damage, particularly in unborn babies. The only way to prevent or ameliorate MeHg toxicity is to enhance its elimination from the body.

OBJECTIVES

Using N-acetylcysteine (NAC), we aimed to devise a monitoring protocol for early detection of acute exposure or relatively low MeHg levels in a rodent model, and to test whether NAC reduces MeHg levels in the developing embryo.

RESULTS

NAC produced a transient, dose-dependent acceleration of urinary MeHg excretion in rats of both sexes. Approximately 5% of various MeHg doses was excreted in urine 2 hr after injection of 1 mmol/kg NAC. In pregnant rats, NAC markedly reduced the body burden of MeHg, particularly in target tissues such as brain, placenta, and fetus. In contrast, NAC had no significant effect on urinary MeHg excretion in preweanling rats.

CONCLUSIONS

Because NAC causes a transient increase in urinary excretion of MeHg that is proportional to the body burden, it is promising as a biomonitoring agent for MeHg in adult animals. In view of this and because NAC is effective at enhancing MeHg excretion when given either orally or intravenously, can decrease brain and fetal levels of MeHg, has minimal side effects, and is widely available in clinical settings, NAC should be evaluated as a potential antidote and biomonitoring agent in humans.

Amoxicillin Pharmacokinetics in (Preterm) Infants Aged 10 to 52 Days: Effect of Postnatal Age

The pharmacokinetic parameters of amoxicillin were determined in 32 newborn infants aged 10 to 52 days (mean postnatal age, 24.7 +/- 12.4 days) to improve amoxicillin dosing in this age group. Amoxicillin plasma concentrations were determined using reversed-phase high-performance liquid chromatography in surplus plasma samples from routine gentamicin assays. Amoxicillin pharmacokinetic parameters (mean +/- SD) were as follows: first-order elimination constant (K(el)) = 0.27 +/- 0.10 h(-1), volume of distribution corrected for body weight (V/W) = 0.66 +/- 0.27 L/kg, total body clearance corrected for body weight (CL/W) = 0.18 +/- 0.10 Lkg(-1)h(-1), and elimination half-life (t(1/2)) = 3.0 +/- 1.3 hours. Amoxicillin body clearance was approximately twofold greater in our patients compared with published values in younger neonates (mean postnatal age, 0.76 +/- 1.57 days). Simulation studies using the observed amoxicillin pharmacokinetic data suggest an amoxicillin dose of 40 mg/kg administered every 8 hours in infants older than 9 days postnatal age, independent of gestational age and postconceptional age, to achieve satisfactory target plasma amoxicillin concentrations less than 140 mg/L and time above minimum inhibitory concentration of at least 40%. Prospective evaluation of this suggested new dosage regimen is necessary before implementation in the care of ill neonates.

Population pharmacokinetics and dosing of amoxicillin in (pre)term neonates

Amoxicillin plasma concentrations, pharmacokinetic parameters, and the influence of demographic, anthropometric, and clinical covariates were investigated in 150 neonates. Gestational age (GA) ranged from 25 to 42 weeks and mean postnatal age (PNA) was 0.8 days. Amoxicillin concentrations were measured with reversed-phase HPLC in surplus plasma from routine assays of coadministered gentamicin. Mean total body clearance corrected for body weight (CL/W) was 0.096 +/- 0.036 L/kg(-1)h(-1), mean elimination half-life (t(1/2)) was 5.2 +/- 1.9 hours, and mean volume of distribution corrected for body weight (V/W) was 0.65 +/- 0.13 L/kg. Multiple regression equations were calculated for the prediction of CL/W amoxicillin. CL/W gentamicin, V/W gentamicin, and GA were significant predictors of CL/W amoxicillin. Amoxicillin peak and trough concentrations after the second dose and the time the concentration exceeds the minimum inhibitory concentration (T>MIC), reached with the current dosage regimen, were evaluated. Toxic plasma concentrations were reached in several patients. Therefore, the authors have proposed a lower dosage regimen, based on GA, population pharmacokinetic parameters, bacterial susceptibility (T>MIC), and possible toxicity: 15 mg/kg per 8 hours and 20 mg/kg per 8 hours for neonates with GA < or = 34 and GA>34 weeks, respectively. Simulation with this new dosage regimen indicated that satisfactory plasma concentrations were reached in all 150 neonates. Therefore, use of therapeutic drug monitoring and pharmacokinetic calculations for dosage adjustment is generally not necessary.

Evaluating the near-term infant for early onset sepsis: progress and challenges to consider with 16S rDNA polymerase chain reaction testing

Although the rate of early onset sepsis in the near-term neonate is low (one to eight of 1,000 cases), the rate of mortality and morbidity is high. As a result, infants receive multiple, broad-spectrum antibiotic therapy, many for up to 7 days despite blood cultures showing no growth. Maternal intrapartum antibiotic prophylaxis and small blood volume collections from infants are cited as reasons for the lack of confidence in negative culture results. Incorporating an additional, more rapid test could facilitate a more timely diagnosis in these infants. To this end, a 16S rDNA polymerase chain reaction (PCR) assay was compared to blood culturing for use as a tool in evaluating early onset sepsis. Of 1,751 neonatal intensive care unit admissions that were screened, 1,233 near-term infants met inclusion criteria. Compared to culture, PCR demonstrated excellent analytical specificity (1,186 of 1,216, 97.5%) and negative predictive value (1,186 of 1,196, 99.2%); however, PCR failed to detect a significant number of culture-proven cases. These findings underscore the cautionary stance that should be taken at this time when considering the use of a molecular amplification test for diagnosing neonatal sepsis. The experience gained from this study illustrates the need for changes in sample collection and preparation techniques so as to improve analytical sensitivity of the assay.

Neonatal chlamydial infections: prevention and treatment

Neonatal chlamydial infection, which manifests principally as ophthalmia neonatorum (ON) or pneumonia, is a significant cause of neonatal morbidity. Widespread use of silver nitrate drops resulted in a dramatic decline in the incidence of gonococcal ophthalmia but had much less impact on the incidence of neonatal chlamydial infection. Chlamydia trachomatis has become the most common infectious cause of ON in developed countries.A number of prophylactic antibiotic or antiseptic agents have been used to prevent ON. Prophylaxis with 1% silver nitrate ophthalmic drops, 0.5% erythromycin ophthalmic ointment, or 1% tetracycline ointment has comparable efficacy for the prevention of chlamydial ophthalmia but does not offer protection against nasopharyngeal colonization or the development of pneumonia. Erythromycin or tetracycline topically have been used as prophylactic agents because of their allegedly superior activity for the prevention of ON and because they produced less chemical conjunctivitis compared with silver nitrate. However, the relative efficacy of these agents for chlamydial infection and the emergence of beta-lactamase-producing Neisseria gonorrheae has raised questions regarding their effectiveness when applied topically for prophylaxis of ON. Compared with these agents, a 2.5% povidone-iodine ophthalmic solution has been found to have greater efficacy for the prevention of ON generally, and chlamydial ophthalmia specifically. In countries where the incidence of ON is very low, an alternative strategy is to institute prenatal screening and treatment of infected mothers, forgo routine neonatal prophylaxis, and follow-up infants after birth for the possible development of infection. For the treatment of chlamydial ophthalmia or pneumonia, oral erythromycin for 2 weeks is recommended; additional topical therapy is unnecessary. However, in approximately 20-30% of infants, therapy will not eradicate the organism and the infant may require a repeat oral course of antibiotics. The few published studies on the use of the new oral macrolide antibiotics, such as azithromycin, roxithromycin, or clarithromycin for chlamydial infections in neonates suggest that these agents may be effective; however, more data on their tolerability and efficacy in this patient group are warranted.

Real-time polymerase chain reaction for detecting bacterial DNA directly from blood of neonates being evaluated for sepsis

Speed is of the essence when evaluating an infant with symptoms consistent with sepsis. Because of the high morbidity and mortality associated with neonatal sepsis, infants receive multiple, broad-spectrum antibiotics before receiving finalized blood culture results. Incorporating an additional, reliable, yet rapid assay to detect bacteria directly from blood would facilitate timely diagnosis and appropriate care. To this end, we designed a real-time polymerase chain reaction (PCR) assay targeting the highly conserved 380 bases of 16S rDNA. DNA was extracted from whole-blood samples using a Qiagen column. The limit of detection for the TaqMan-based assay, using a Smartcycler instrument, was 40, 50, or 2000 colony-forming units per milliliter of blood (CFU/ml) of Escherichia coli, group B Streptococcus, and Listeria monocytogenes, respectively, when white blood cell counts were below 39,000/microl. Implementing this approach requires less than 4 hours for both sample preparation and real-time PCR compared with 1 to 2 days to detect growth in culture or 5 days to finalize no-growth culture results. There was an overall agreement between the results of culture and real-time PCR of 94.1% (80 of 85) in this study. These results suggest that molecular techniques can augment culture-based methods for diagnosing neonatal sepsis, especially in infants whose mothers have received intrapartum antibiotic prophylaxis.

New dosing strategies for antibacterial agents in the neonate

Dosing of antibiotics in neonates requires finding a delicate balance between maximal efficacy and minimal toxicity. There is a lack of data on efficacy of currently used antibiotics in neonates, and rational dosing therefore needs to be based on gestational- and postnatal-age-dependent pharmacokinetics in combination with surrogate markers. These surrogate markers are: (i) the area-under-the serum concentration time curve to minimum inhibitory concentration ratio (AUC/MIC); (ii) peak concentration to MIC ratio (Cmax/MIC); and (iii) the time the concentration remains above the MIC (T>MIC). Whereas the efficacy of beta-lactam antibiotics (including carbapenems) depends on T>MIC, the efficacy of most other antimicrobials (including aminoglycosides and fluoroquinolones) is related to AUC/MIC and Cmax/MIC. Most modern dosing regimens are adequate when these concentration effect relationships are taken into account. Dosing adjustments in neonates are suggested, based on these relationships. Several antimicrobial combinations for treatment of meningitis and necrotizing enterocolitis exist. Empiric treatment should be based on efficacy, concerns about resistance as well as information from institutional microbiological surveillance.

Experimental study of teicoplanin, alone and in combination, in the therapy of cephalosporin-resistant pneumococcal meningitis

OBJECTIVES

The aim of the study was to determine the efficacy of teicoplanin, alone and in combination with ceftriaxone, in a rabbit model of cephalosporin-resistant pneumococcal meningitis, and to assess the effect of concomitant therapy with dexamethasone.

METHODS

In vitro killing curves of teicoplanin, with and without ceftriaxone, were performed. Groups of eight animals per treatment were inoculated with a cephalosporin-resistant pneumococcal strain (penicillin MIC, 4 mg/L; ceftriaxone MIC, 2 mg/L; teicoplanin MIC, 0.03 mg/L) and treated over a 26 h period. Teicoplanin was administered at a dose of 15 mg/kg, alone and in combination with ceftriaxone at 100 mg/kg with or without dexamethasone at 0.25 mg/kg. CSF samples were collected at different time-points, and bacterial titres, white blood cell counts, lactate and protein concentrations and bacteriostatic/bactericidal titres were determined. Blood and CSF teicoplanin pharmacokinetic and pharmacodynamic parameters were determined.

RESULTS

Teicoplanin alone promoted a decrease in bacterial counts at 6 h of -2.66 log cfu/mL and was bactericidal at 24 h, without therapeutic failures. Similar good results were obtained when dexamethasone was used simultaneously, in spite of the penetration of teicoplanin into the CSF being significantly reduced, from 2.31% to 0.71%. Teicoplanin and ceftriaxone combinations were synergic in vitro, but not in the meningitis model.

CONCLUSIONS

Teicoplanin alone was very effective in this model of cephalosporin-resistant pneumococcal meningitis. The use of concomitant dexamethasone resulted in lower CSF teicoplanin levels, but not in therapeutic failures. The combination of teicoplanin plus ceftriaxone and dexamethasone might be a good alternative for the empirical therapy of pneumococcal meningitis. Additional data should confirm our experiments, in advance of clinical trials to assess efficacy in humans.

Étude de la corrélation entre les prescriptions d’antibiotiques et les recommandations dans une unité de soins intensifs néonatals

The increasing use of wide spectrum antibiotics has been reported to be associated with a greater prevalence of multi-resistant bacteria.

OBJECTIVES

The aims of this study were to survey the use of antibiotics and to evaluate the correlations between patterns of prescription of antibiotics and prescription guidelines in a neonatal intensive care unit.

MATERIAL AND METHODS

In this 6-month study, all newborns admitted to the NICU and treated with antibiotics were included. Data regarding criteria of antibiotic prescription, length of treatment, and criteria of withdrawing treatment were collected. The correlation between prescriptions and guidelines was evaluated a posteriori by a non-prescriber physician. One hundred and sixteen newborns were included, of whom nine had received antibiotics on more than one occasion. Mean gestational age was 33.5 weeks. In 82% of cases, the reason for hospitalisation was respiratory distress syndrome.

RESULTS

Patients received systemic antibiotics for primary infection (78%), nosocomial infection (17%) and postsurgical prophylaxis (5%). Suspected foeto-maternal infections (SFMI) were the dominant features of primary infection (96%). In 49% of cases, suspected infection was not proven and justified withdrawal of treatment within 3 days. Sixty percent of nosocomial infections occurred in newborns with gestational ages of less than 28 weeks. Bacterial criteria were decision-making factors only in nosocomial infections. An absence of observance of guidelines occurred in 9% of treated newborns, and in most cases involved excessive length of treatment.

CONCLUSION

These results show: (1) the majority of antibiotic prescriptions were for not proven SMFI; (2) a low rate of nosocomial infections; (3) the predominance of nosocomial infections in premature newborns; (4) less than 10% of non-observance of guidelines. It appears necessary to develop more precise guidelines to limit antibiotic use and to evaluate them regularly.

Six day antimicrobial therapy for early-onset group B streptococcal infection in near-term and term neonates

Antibiotics for the treatment of group B streptococcal (GBS) infection are usually given for 7-10 d. The aim of this prospective investigation was to study whether antibiotic treatment for 6 d is sufficient to treat early-onset GBS infection in term and near-term neonates. During a 2 y period 67 neonates of GBS-positive mothers developed GBS infection and were admitted to the neonatal intensive care unit. All neonates showed clinical signs of infection, C-reactive protein levels > 20 mg/l and/or elevated immature to total neutrophil ratio > 0.25. Two groups were differentiated: 10 neonates with proven sepsis with GBS-positive blood cultures (15%) and 57 neonates with presumed GBS infection with negative blood cultures but with GBS-positive surface swab cultures of ear (68%), nasopharyngeal (21%) or gastric aspirate (16%). All patients were GBS positive in 1 or more cultures. Antimicrobial therapy with ampicillin and cefotaxime was discontinued after 6 d. At that time all neonates were asymptomatic and laboratory results were normal. No relapse or death within 4 weeks after therapy was detected. In conclusion, antibiotic therapy for 6 d was sufficient to treat 10 neonates with proven and 57 neonates with presumed early-onset GBS infection. Owing to the small sample size, further studies are needed to show significant differences to longer therapy regimens.

Linezolid for the treatment of children with bacteremia or nosocomial pneumonia caused by resistant gram-positive bacterial pathogens

BACKGROUND

Nosocomial infections, particularly hospital-acquired pneumonia (HAP) and bacteremia, are an increasing concern in pediatric hospitals and pediatric intensive care units. Gram-positive pathogens are a leading cause of these infections in children. Linezolid is well-tolerated and as effective as vancomycin in the treatment of these infections in adults.

OBJECTIVE

To evaluate the clinical effectiveness and safety of iv/oral linezolid and iv vancomycin in children with resistant Gram-positive HAP or bacteremia.

METHODS

Hospitalized children <12 years of age were randomized 2:1 to linezolid or vancomycin. Patients received linezolid 10 mg/kg iv every 8 h with the option to change treatment to oral linezolid suspension 10 mg/kg every 8 h or iv vancomycin 10 to 15 mg/kg every 6 to 24 h. Clinical response was evaluated at follow-up. Results from an analysis of patients with HAP or bacteremia are presented.

RESULTS

Thirty-nine patients (linezolid, 23; vancomycin, 16) with HAP and 113 patients with bacteremia (linezolid, 81; vancomycin, 32) were included in the intent-to-treat group. Clinical cure rates for clinically evaluable patients with HAP did not differ between treatment groups (linezolid, 90.0% and vancomycin, 100%; P = 0.305). No significant difference was seen in clinical cure rates in the clinically evaluable population between the linezolid and vancomycin groups for patients with catheter-related bacteremia (84.8 and 80.0%, respectively; P = 0.716) or patients with bacteremia of unknown source (79.2 and 69.2%, respectively; P = 0.501). In this subset fewer linezolid-treated patients had drug-related adverse events than did vancomycin-treated patients (19.4% vs. 28.3%; P = 0.230). Similar percentages of patients with laboratory abnormalities, including selected hematologic parameters, were seen in both treatment groups.

CONCLUSIONS

Intravenous/oral linezolid was well-tolerated and as effective as vancomycin in treating children with resistant Gram-positive HAP or bacteremia.

Efficacy and safety of arbekacin for staphylococcal infection in the NICU

BACKGROUND

This is a retrospective study on the efficacy and safety of arbekacin (ABK), an aminoglycoside antibiotic, for acquired staphylococcal infection in the neonatal intensive care nursery.

PATIENTS AND METHODS

Subjects were 29 infants treated with ABK in a tertiary care neonatal center. They were 23-39 (median 28) weeks' gestation, 530-3334 (median 930) grams at birth, and 3-157 (median 17) days of age. Diagnosis of staphylococcal infection was made by clinical signs and laboratory findings. Sensitivity of the isolated organisms to ABK was tested by the microliquid dilution method. Serum ABK level was monitored to achieve the therapeutic range during the treatment. Effectiveness was defined by improving clinical signs and laboratory findings within 3 days. Effectiveness was studied in relation to type of infection and other antibiotics administered. Auditory brainstem response and serum creatinine changes were studied for ototoxicity and nephrotoxicity assessment, respectively.

RESULTS

Twenty-seven (93.1%) cases of infection were attributed to methicillin-resistant Staphylococcus aureus (MRSA) and two (6.9%) were attributed to coagulase-negative staphylococci (CNS). The rate of in vitro sensitivity to ABK was 85.2% for MRSA and 100.0% for CNS. The overall clinical effeciveness rate was 79.3% (23/29) with no difference associated with types of infection. Combination of ABK with sulbactam/ampicillin showed greater effectiveness (100.0%) than with other antibiotics (64.3%) (P < 0.05). There was no abnormal auditory brainstem response or serum creatinine change associated with ABK treatment.

CONCLUSION

ABK is an effective and safe antibiotic for the treatment of acquired staphylococcal infection in the neonatal intensive care nursery.

Pharmacokinetics and dosing of arbekacin in preterm and term newborn infants

BACKGROUND

The objective of the present study was to determine pharmacokinetic variables and to characterize a new initial dosing regimen of arbekacin (ABK) for preterm and term newborn infants.

PATIENTS AND METHODS

Subjects were 40 infants treated with ABK in a tertiary care neonatal unit over a period of 18 months. At birth, the infants were 23 5/7-40 0/7 weeks and weighed 530-3428 g. Serum ABK concentration was measured at two points in a course of treatment. Data were analyzed by a one-compartment model to obtain volume of distribution (Vd) and clearance (CL) of ABK. These variables were correlated with the patients' demographic and laboratory data. The new initial dosing regimen was determined based on these data.

RESULTS

Sixty pairs of blood samples were taken from the infants. They were divided into three groups: preterm early (PE), gestational age (GA) < 37 weeks and postnatal age (PNA) < 28 days; preterm late (PL), GA < 37 weeks and PNA >or= 28 days; and term (T), GA >or= 37 weeks and PNA < 28 days. The Vd was 0.50 +/- 0.02, 0.48 +/- 0.04, and 0.43 +/- 0.03 L/kg, and CL was 0.59 +/- 0.04, 1.12 +/- 0.10, and 0.78 +/- 0.09 mL/min per kg (mean +/- SEM) in PE, PL, and T, respectively. The new dosing regimen is 5 mg/kg every 48 h, 5 mg/kg every 24 h, and 4 mg/kg every 24 h for PE, PL, and T, respectively.

CONCLUSIONS

With the new dosing regimen, more infants achieved serum ABK levels within the optimal range than the conventional one.

Dose regimen for vancomycin not needing serum peak levels?

AIM

To determine the safety, efficacy, and need to measure peak serum vancomycin concentrations in a neonatal population using a standard vancomycin dosage regimen.

METHOD

A total of 101 infants who were admitted to a regional neonatal intensive care unit and received vancomycin (15 mg/kg every 12 or 18 hours depending on postnatal age) were studied retrospectively. Infants who had been started on vancomycin before they were transferred to the unit were excluded. The proportion of infants was measured whose serum vancomycin concentrations were within a conservative therapeutic range of trough 5-10 mg/l, peak 20-40 mg/l, and a less conservative, but still safe, range of trough 5-12 mg/l, peak 15-60 mg/l.

RESULTS

Trough concentrations of 5-10 mg/l were achieved by 46.5% of infants, and 5-12 mg/l by 55.4%. Peak concentrations of 20-40 mg/l were found in 83.2% of infants, and 15-60 mg/l in 99.0%. Highest peak concentration was 47.2 mg/l. Some 89.4% of infants with trough concentrations of 5-10 mg/l had a peak concentration of 20-40 mg/l.

CONCLUSIONS

The vancomycin dosage regimen used in this study produces acceptable therapeutic serum vancomycin concentrations. Peak serum vancomycin concentrations do not need to be measured in neonates using this dosage regimen.

Population pharmacokinetics and relationship between demographic and clinical variables and pharmacokinetics of gentamicin in neonates

Population pharmacokinetic parameter estimates were calculated from 725 routine plasma gentamicin concentrations obtained in 177 neonates of 24 to 42 weeks' gestational age in their first week of life. Kel increases and V/W decreases with increasing gestational age. Almost identical results were obtained with iterative two-stage Bayesian fitting (MW\PHARM 3.30) as with a non-parametric maximization algorithm (NPEM2). The effect of various covariates on drug disposition was investigated retrospectively using multiple regression analysis. Predictive power for Kel increases with rising gestational age. For neonates </=28.5 weeks and neonates >28.5 weeks and </=30.9 weeks, the predictive power of the regression equation for Kel was relatively low (r2 respectively 0.270 and 0.364). Better predictivity was found for Kel at gestational ages >30.9 weeks (r2 = 0.482), with gestational age, postnatal age, and Apgar score at 5 minutes being predictors. A very strong correlation existed between volume of distribution and weight (r2 = 0.83). Volume as a function of weight could be described with low predictivity by gestational age and to a lesser degree by Apgar score at 5 minutes (r2 = 0.298). The developed models need appropriate prospective clinical validation.

Nosocomial pneumonia in pediatric patients: practical problems and rational solutions

Nosocomial pneumonia is a common hospital-acquired infection in children, and is often fatal. Risk factors for nosocomial pneumonia include admission to an intensive care unit, intubation, burns, surgery, and underlying chronic illness. Viruses, predominantly respiratory syncytial virus (RSV), are the most common cause of pediatric nosocomial respiratory tract infections. Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa) are the predominant bacterial pathogens, and are associated with a high mortality rate. Staphylococcus aureus and Staphylococcus epidermidis are the most common Gram-positive bacteria causing nosocomial pneumonia; infections with these organisms have a better outcome than those with Gram-negative organisms. An increasing problem is the emergence of multiresistant Gram-positive and Gram-negative nosocomial pathogens. Distinguishing nosocomial pneumonia from other pulmonary processes may be difficult; diagnosis is based on clinical signs, radiological findings, and microbiological results. Recommended empiric therapy should consider factors such as the time of onset of illness, severity of disease, and specific risk factors for nosocomial pneumonia, including use of mechanical ventilation, underlying disease, or recent use of antibacterials. The resident local hospital flora should be considered when selecting therapy for nosocomial pneumonia. Early initiation of appropriate empiric therapy reduces morbidity and mortality. For empiric treatment of bacterial nosocomial pneumonia, an intravenous antibacterial regimen that includes coverage of Gram-negative bacilli and Gram-positive organisms should be used. A carbapenem or ureidopenicillin derivative (piperacillin) plus a beta-lactamase inhibitor should be used where extended spectrum beta-lactamase-producing Enterobacteriaceae are endemic. Therapy should be modified when a specific pathogen and its antimicrobial susceptibility are identified. Effective prevention of nosocomial pneumonia requires infection control measures that affect the environment, personnel, and patients. Of these, hand hygiene, appropriate infection control policies, and judicious use of antibacterials are essential.

Gender-specific and developmental influences on the expression of rat organic anion transporters

Rat organic anion transporter 1 (Oat1), Oat2, and Oat3, members of the organic anion transporter family, transport some organic anions across cellular membranes. Previously, highest Oat1 and Oat3 mRNA expression was reported in kidney and Oat2 in liver. However, gender and developmental differences in Oat expression remain unknown. This study describes gender- and age-specific patterns of rat organic anion transporter expression in various tissues. Oat mRNA expression was evaluated in adult male and female Sprague-Dawley rat tissues, and developmental expression was also determined in kidneys of Sprague-Dawley rats ranging in age from days 0 through 45. Expression was quantified using branched-DNA signal amplification. Oat1 mRNA expression was primarily observed in kidney. Surprisingly, Oat2 mRNA expression was also highest in kidney rather than in liver. Moreover, considerably higher Oat2 levels were seen in female kidney as compared with male. Finally, Oat3 mRNA expression was highest in kidney of both genders, whereas a male-predominant pattern was observed in liver. At birth, all kidney Oat mRNA levels were low. Renal Oat1 expression gradually increased throughout development, approaching adult levels at 30 days of age, where at days 40 and 45 Oat1 levels were greater in males than females. Oat2 expression in kidney was minimal through day 30 but increased dramatically at day 35 in females only. Lastly, Oat3 mRNA expression in kidney matured earliest, rapidly increasing from birth through day 10. These data indicate that Oat mRNA expression is primarily localized to the kidney, and observed expression patterns may explain some previously recognized age- and gender-dependent toxicities associated with chemical exposure.

Aetiology and management of children with acute fever of unknown origin

This is part I of a 2-part paper on fever of unknown origin (FUO) in children. FUO is best defined as fever without obvious source on initial clinical examination and then classified into acute (illness of < or =1 week's duration) and prolonged (>7 to 10 days' duration). Aetiologically, there is a marked overlap between acute and prolonged FUO, and infections are major players in both. Age, climate, local epidemiology and host factors are the major aetiological factors that should be considered in the choice of definitive tests. Depending on age, serious bacterial infections (including bacteraemia, meningitis and urinary tract infection) occur in 3 to 20% of cases of acute FUO. Prevention of mortality and sequelae from these infections, particularly bacteraemia and meningitis, is of particular concern in acute FUO. An individualised approach, based on clinical evaluation supplemented with screening and definitive laboratory tests to determine the need for empiric antibiotic therapy and hospitalisation, seems to be the best approach to acute FUO (although this may be less applicable to neonates and infants younger than 90 days, particularly those aged 0 to 7 days). The place of laboratory tests, empiric antibiotic therapy and hospitalisation are important issues that are likely to remain so for some time.

C-reactive protein and serum amyloid A protein in neonatal infections

In this study, we examine C-reactive protein (CRP) and serum amyloid protein A (SAA). Although the former is the best known and most commonly used indicator of inflammation, certain considerations underline the inadequacy of CRP determination alone for the early diagnosis of infection. In fact symptoms often precede the CRP elevation. SAA protein comprises a family of polymorphic apolipoproteins produced mainly by the liver, and several studies have stressed its importance in the diagnosis and monitoring of various diseases. Pathological SAA values are often detected in association with normal CRP concentrations. SAA rises earlier and more sharply than CRP. Finally, contrary to CRP, SAA presents the same trend in viral as well as bacterial infections. Although the data available on SAA in neonates are currently very limited, it is possible to postulate a role of primary importance for SAA in the management of neonatal infections.