Antibiotic treatment duration and prevention of complications in neonatal Staphylococcus aureus bacteraemia.

BACKGROUND: In adults with Staphylococcus aureus bacteraemia, short duration of effective antibiotic treatment is associated with increased risk of complications and recurrence. The optimum duration of treatment for neonates is unknown and practice varies widely. AIM: To relate the duration of treatment of neonatal S. aureus bacteraemia to prevention of complications and recurrence. METHODS: Retrospective cohort study of confirmed S. aureus bacteraemia occurring over a 10 year period in two large tertiary neonatal units. Neonatal patients developing confirmed S. aureus bacteraemia between birth and discharge from the neonatal unit were identified from microbiology department records. Clinical details obtained from case notes included demographics, duration of antibiotics and clinical outcomes. Recurrence was determined from laboratory and clinical records. Adverse outcomes were related to duration of antibiotic therapy. FINDINGS: A total of 90 infants had S. aureus bacteraemia, of which six were meticillin-resistant S. aureus (7%). Median gestation was 27 weeks (range: 23-41), birth weight 846 g (434-3840) and postnatal age 16 days (0-116). Adverse outcomes were found in 44%, with death in 8%. Median duration of appropriate antibiotics was 19 days (range: 0-54). There were no cases of recurrent bacteraemia after finishing antibiotics. There was no relationship between antibiotic duration and complications. CONCLUSION: Neonatal S. aureus bacteraemia mainly affected preterm neonates and had a significant morbidity and mortality. Recurrent bacteraemia was rare, irrespective of treatment duration. For neonatal unit patients with S. aureus bacteraemia, antibiotic therapy for 14 days in uncomplicated cases may be sufficient to prevent recurrence, with longer treatment justified if there is inadequate source control.

Perinatal cortical growth and childhood neurocognitive abilities.

OBJECTIVE: This observational cohort study addressed the hypothesis that after preterm delivery brain growth between 24 and 44 weeks postmenstrual age (PMA) is related to global neurocognitive ability in later childhood. METHODS: Growth rates for cerebral volume and cortical surface area were estimated in 82 infants without focal brain lesions born before 30 weeks PMA by using 217 magnetic resonance images obtained between 24 and 44 weeks PMA. Abilities were assessed at 2 years using the Griffiths Mental Development Scale and at 6 years using the Wechsler Preschool and Primary Scale of Intelligence-Revised (WPPSI-R), the Developmental Neuropsychological Assessment (NEPSY), and the Movement Assessment Battery for Children (MABC). Analysis was by generalized least-squares regression. RESULTS: Mean test scores approximated population averages. Cortical growth was directly related to the Griffiths Developmental Quotient (DQ), the WPPSI-R full-scale IQ, and a NEPSY summary score but not the MABC score and in exploration of subtests to attention, planning, memory, language, and numeric and conceptual abilities but not motor skills. The mean (95% confidence interval) estimated reduction in cortical surface area at term corrected age associated with a 1 SD fall in test score was as follows: DQ 7.0 (5.8-8.5); IQ 6.0 (4.9-7.3); and NEPSY 9.1 (7.5-11.0) % · SD(-1). Total brain volume growth was not correlated with any test score. CONCLUSIONS: The rate of cerebral cortical growth between 24 and 44 weeks PMA predicts global ability in later childhood, particularly complex cognitive functions but not motor functions.

Predicting motor outcome and death in term hypoxic-ischemic encephalopathy.

OBJECTIVES: Central gray matter damage, the hallmark of term acute perinatal hypoxia-ischemia, frequently leads to severe cerebral palsy and sometimes death. The precision with which these outcomes can be determined from neonatal imaging has not been fully explored. We evaluated the accuracy of early brain MRI for predicting death, the presence and severity of motor impairment, and ability to walk at 2 years in term infants with hypoxic-ischemic encephalopathy (HIE) and basal ganglia-thalamic (BGT) lesions. METHODS: From 1993 to 2007, 175 term infants with evidence of perinatal asphyxia, HIE, and BGT injury seen on early MRI scans were studied. BGT, white matter, posterior limb of the internal capsule (PLIC), and cortex and brainstem abnormality were classified by severity. Motor impairment was staged using the Gross Motor Function Classification System. RESULTS: The severity of BGT lesions was strongly associated with the severity of motor impairment (Spearman rank correlation 0.77; p < 0.001). The association between white matter, cortical, and brainstem injury and motor impairment was less strong and only BGT injury correlated significantly in a logistic regression model. The predictive accuracy of severe BGT lesions for severe motor impairment was 0.89 (95% confidence interval 0.83-0.96). Abnormal PLIC signal intensity predicted the inability to walk independently by 2 years (sensitivity 0.92, specificity 0.77, positive predictive value 0.88, negative predictive value 0.85). Brainstem injury was the only factor with an independent association with death. CONCLUSION: We have shown that in term newborns with HIE and BGT injury, early MRI can be used to predict death and specific motor outcomes.

High b-value diffusion tensor imaging of the neonatal brain at 3T.

BACKGROUND AND PURPOSE: Diffusion-weighted MR imaging studies of the adult brain have shown that contrast between lesions and normal tissue is increased at high b-values. We designed a prospective study to test the hypothesis that diffusion tensor imaging (DTI) obtained at high b-values increases image contrast and lesion conspicuity in the neonatal brain. MATERIALS AND METHODS: We studied 17 neonates, median (range) age of 10 (2-96) days, who were undergoing MR imaging for clinical indications. DTI was performed on a Philips 3T Intera system with b-values of 350, 700, 1500, and 3000 s/mm(2). Image contrast and lesion conspicuity at each b-value were visually assessed. In addition, regions of interest were positioned in the central white matter at the level of the centrum semiovale, frontal and occipital white matter, splenium of the corpus callosum, posterior limb of the internal capsule, and the thalamus. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values for these regions were calculated. RESULTS: Isotropic diffusion image contrast and lesion-to-normal-tissue contrast increased with increasing b-value. ADC values decreased with increasing b-value in all regions studied; however, there was no change in FA with increasing b-value. CONCLUSIONS: Diffusion image contrast increased at high b-values may be useful in identifying lesions in the neonatal brain.