Towards accurate exclusion of neonatal bacterial meningitis: a feasibility study of a novel 16S rDNA PCR assay.

BACKGROUND: PCRctic is an innovative assay based on 16S rDNA PCR technology that has been designed to detect a single intact bacterium in a specimen of cerebro-spinal fluid (CSF). The assay's potential for accurate, fast and inexpensive discrimination of bacteria-free CSF makes it an ideal adjunct for confident exclusion of bacterial meningitis in newborn babies where the negative predictive value of bacterial culture is poor. This study aimed to stress-test and optimize PCRctic in the "field conditions" to attain a clinically useful level of specificity. METHODS: The specificity of PCRctic was evaluated in CSF obtained from newborn babies investigated for meningitis on a tertiary neonatal unit. Following an interim analysis, the method of skin antisepsis was changed to increase bactericidal effect, and snap-top tubes (Eppendorf™) replaced standard universal containers for collection of CSF to reduce environmental contamination. RESULTS: The assay's specificity was 90.5% in CSF collected into the snap-top tubes - up from 60% in CSF in the universal containers. The method of skin antisepsis had no effect on the specificity. All CSF cultures were negative and no clinical cases of neonatal bacterial meningitis occurred during the study. CONCLUSIONS: A simple and inexpensive optimization of CSF collection resulted in a high specificity output. The low prevalence of neonatal bacterial meningitis means that a large multi-centre study will be required to validate the assay's sensitivity and its negative predictive value.

Thyrotropic hormones.

Thyroid hormones are crucial for normal cognition and neurodevelopment in children. The introduction of the screening programs for congenital hypothyroidism has decreased the incidence of untreated congenital hypothyroidism. As maternal thyroid disease is common, and may impact on thyroid gland development and function in the fetus, optimal management is crucial. This review discusses thyroid function and the impact of maternal thyroid disease on the fetus and neonate, as well as the influence of thyroid hormones, thyroid antibodies and the excretion of thyroid medication into breast milk on infant thyroid function.

Relationship between insulin-like growth factor I levels, early insulin treatment, and clinical outcomes of very low birth weight infants.

OBJECTIVES: Insulin regulates the secretion of insulin-like growth factor I (IGF-I) in the newborn, and low levels of IGF-I have been linked to neonatal morbidity. As part of the Neonatal Insulin Replacement Therapy in Europe Trial, we investigated the impact of early insulin treatment on IGF-I levels and their relationship with morbidity and growth. STUDY DESIGN: Prospective cohort analyses of data collected as part of an international randomized controlled trial. Blood samples (days 1, 3, 7, and 28), were taken for IGF-I bioassay from 283 very low birth weight infants (<1500 g). RESULTS: Early insulin treatment led to a late increase in IGF-I levels between day 7 and 28 (P = .028). In the first week of life IGF-I levels were lower in infants with early hyperglycemia; mean difference -0.10 µg/L (95% CI -0.19, -0.02, P = .02). Lower levels of IGF-I at day 28 were independently associated with an increased risk of chronic lung disease, OR 3.23 (95% CI, 1.09-9.10), and greater IGF-I levels were independently associated with better weight gain, 0.10 kg (95% CI, 0.03-0.33, P = .02). CONCLUSIONS: Early intervention with insulin is related to increased IGF-I levels at 28 days. Low IGF-I levels are associated with hyperglycemia, increased morbidity, and reduced growth. Increasing IGF-I levels may improve outcomes of very low birth weight infants.

Whole-genome sequencing for analysis of an outbreak of meticillin-resistant Staphylococcus aureus: a descriptive study.

BACKGROUND: The emergence of meticillin-resistant Staphylococcus aureus (MRSA) that can persist in the community and replace existing hospital-adapted lineages of MRSA means that it is necessary to understand transmission dynamics in terms of hospitals and the community as one entity. We assessed the use of whole-genome sequencing to enhance detection of MRSA transmission between these settings. METHODS: We studied a putative MRSA outbreak on a special care baby unit (SCBU) at a National Health Service Foundation Trust in Cambridge, UK. We used whole-genome sequencing to validate and expand findings from an infection-control team who assessed the outbreak through conventional analysis of epidemiological data and antibiogram profiles. We sequenced isolates from all colonised patients in the SCBU, and sequenced MRSA isolates from patients in the hospital or community with the same antibiotic susceptibility profile as the outbreak strain. FINDINGS: The hospital infection-control team identified 12 infants colonised with MRSA in a 6 month period in 2011, who were suspected of being linked, but a persistent outbreak could not be confirmed with conventional methods. With whole-genome sequencing, we identified 26 related cases of MRSA carriage, and showed transmission occurred within the SCBU, between mothers on a postnatal ward, and in the community. The outbreak MRSA type was a new sequence type (ST) 2371, which is closely related to ST22, but contains genes encoding Panton-Valentine leucocidin. Whole-genome sequencing data were used to propose and confirm that MRSA carriage by a staff member had allowed the outbreak to persist during periods without known infection on the SCBU and after a deep clean. INTERPRETATION: Whole-genome sequencing holds great promise for rapid, accurate, and comprehensive identification of bacterial transmission pathways in hospital and community settings, with concomitant reductions in infections, morbidity, and costs. FUNDING: UK Clinical Research Collaboration Translational Infection Research Initiative, Wellcome Trust, Health Protection Agency, and the National Institute for Health Research Cambridge Biomedical Research Centre.

Rapid whole-genome sequencing for investigation of a neonatal MRSA outbreak.

BACKGROUND: Isolates of methicillin-resistant Staphylococcus aureus (MRSA) belonging to a single lineage are often indistinguishable by means of current typing techniques. Whole-genome sequencing may provide improved resolution to define transmission pathways and characterize outbreaks. METHODS: We investigated a putative MRSA outbreak in a neonatal intensive care unit. By using rapid high-throughput sequencing technology with a clinically relevant turnaround time, we retrospectively sequenced the DNA from seven isolates associated with the outbreak and another seven MRSA isolates associated with carriage of MRSA or bacteremia in the same hospital. RESULTS: We constructed a phylogenetic tree by comparing single-nucleotide polymorphisms (SNPs) in the core genome to a reference genome (an epidemic MRSA clone, EMRSA-15 [sequence type 22]). This revealed a distinct cluster of outbreak isolates and clear separation between these and the nonoutbreak isolates. A previously missed transmission event was detected between two patients with bacteremia who were not part of the outbreak. We created an artificial "resistome" of antibiotic-resistance genes and demonstrated concordance between it and the results of phenotypic susceptibility testing; we also created a "toxome" consisting of toxin genes. One outbreak isolate had a hypermutator phenotype with a higher number of SNPs than the other outbreak isolates, highlighting the difficulty of imposing a simple threshold for the number of SNPs between isolates to decide whether they are part of a recent transmission chain. CONCLUSIONS: Whole-genome sequencing can provide clinically relevant data within a time frame that can influence patient care. The need for automated data interpretation and the provision of clinically meaningful reports represent hurdles to clinical implementation. (Funded by the U.K. Clinical Research Collaboration Translational Infection Research Initiative and others.).

Prevalence and determinants of hyperglycemia in very low birth weight infants: cohort analyses of the NIRTURE study.

OBJECTIVES: To investigate the prevalence and determinants of hyperglycemia in the preterm population, as part of the Neonatal Insulin Therapy in Europe (NIRTURE) Trial. STUDY DESIGN: We conducted prospective cohort analyses of continuous glucose monitoring data from control infants participating in an international randomized controlled trial. Data were collected from 188 very low birth weight infants (<1500 g). RESULTS: In the first week of life, 80% of infants had evidence of glucose levels >8 mmol/L, and 32% had glucose levels >10 mmol/L >10% of the time. Independent risk factors for hyperglycemia included increasing prematurity, small size at birth, use of inotropes, lipid infusions, and sepsis. There was a lack of association between rate of dextrose infused and risk of hyperglycemia. CONCLUSION: The prevalence of hyperglycemia in the very low birth weight infant is high, with marked variability in prevalence between infants, not simply related to rates of glucose infused, but to other potentially modifiable risk factors.

Early insulin therapy in very-low-birth-weight infants.

BACKGROUND: Studies involving adults and children being treated in intensive care units indicate that insulin therapy and glucose control may influence survival. Hyperglycemia in very-low-birth-weight infants is also associated with morbidity and mortality. This international randomized, controlled trial aimed to determine whether early insulin replacement reduced hyperglycemia and affected outcomes in such neonates. METHODS: In this multicenter trial, we assigned 195 infants to continuous infusion of insulin at a dose of 0.05 U per kilogram of body weight per hour with 20% dextrose support and 194 to standard neonatal care on days 1 to 7. The efficacy of glucose control was assessed by continuous glucose monitoring. The primary outcome was mortality at the expected date of delivery. The study was discontinued early because of concerns about futility with regard to the primary outcome and potential harm. RESULTS: As compared with infants in the control group, infants in the early-insulin group had lower mean (+/-SD) glucose levels (6.2+/-1.4 vs. 6.7+/-2.2 mmol per liter [112+/-25 vs. 121+/-40 mg per deciliter], P=0.007). Fewer infants in the early-insulin group had hyperglycemia for more than 10% of the first week of life (21% vs. 33%, P=0.008). The early-insulin group had significantly more carbohydrate infused (51+/-13 vs. 43+/-10 kcal per kilogram per day, P<0.001) and less weight loss in the first week (standard-deviation score for change in weight, -0.55+/-0.52 vs. -0.70+/-0.47; P=0.006). More infants in the early-insulin group had episodes of hypoglycemia (defined as a blood glucose level of <2.6 mmol per liter [47 mg per deciliter] for >1 hour) (29% in the early-insulin group vs. 17% in the control group, P=0.005), and the increase in hypoglycemia was significant in infants with birth weights of more than 1 kg. There were no differences in the intention-to-treat analyses for the primary outcome (mortality at the expected date of delivery) and the secondary outcome (morbidity). In the intention-to-treat analysis, mortality at 28 days was higher in the early-insulin group than in the control group (P=0.04). CONCLUSIONS: Early insulin therapy offers little clinical benefit in very-low-birth-weight infants. It reduces hyperglycemia but may increase hypoglycemia (Current Controlled Trials number, ISRCTN78428828.)

Early elective insulin therapy can reduce hyperglycemia and increase insulin-like growth factor-I levels in very low birth weight infants.

OBJECTIVE: To investigate the use of insulin throughout the first week of life in very low birth weight (VLBW) infants (birth weight <1.5 kg) to improve glucose control and increase insulin-like growth factor-I (IGF-I) levels. IGF-I is the dominant hormone involved in fetal growth, and low levels have been implicated in neonatal morbidities, such as retinopathy of prematurity. STUDY DESIGN: In this pilot randomized controlled study (n = 16), the intervention group received insulin (0.025 U/kg/hr) on days 1 to 7, with 20% dextrose to maintain normoglycemia. Control infants received standard neonatal care. All infants received continuous glucose monitoring. RESULTS: The intervention and standard care groups had similar mean gestational age (+/- standard deviation), 26.2 (+/- 2.5) vs 26.9 (+/- 2.7) weeks, and birth weight, 0.79 (+/- 0.26) vs 0.73 (+/- 0.16) kg. The standard care infants were hyperglycemic (sensor glucose >10 mmol/L [180 mg/dL]) for 35.9% of the study period, compared with 7.6% for the insulin-treated infants (P = .035). The duration of time with hypoglycemia (<2.6 mmol/L [47 mg/dL]) did not differ between the 2 groups (P = .746). The insulin-treated group had a 2.4-fold increase in mean IGF-I bioactivity (P = .005). CONCLUSIONS: Early insulin therapy improves blood glucose control and increases IGF-I bioactivity levels. This could result in less morbidity associated with hyperglycemia and reduced IGF-I levels.

A randomised controlled trial of early insulin therapy in very low birth weight infants, "NIRTURE" (neonatal insulin replacement therapy in Europe).

BACKGROUND: Studies in adult intensive care have highlighted the importance of insulin and improved glucose control on survival, with 32% reduction in mortality, 22% reduction in intensive care stay and halving of the incidence of bacteraemia. Very low birth weight infants requiring intensive care also have relative insulin deficiency often leading to hyperglycaemia during the first week of life. The physiological influences on insulin secretion and sensitivity, and the potential importance of glucose control at this time are not well established. However there is increasing evidence that the early postnatal period is critical for pancreatic development. At this time a complex set of signals appears to influence pancreatic development and beta cell survival. This has implications both in terms of acute glucose control but also relative insulin deficiency is likely to play a role in poor postnatal growth, which has been associated with later motor and cognitive impairment, and fewer beta cells are linked to risk of type 2 diabetes later in life. METHODS: A multi-centre, randomised controlled trial of early insulin replacement in very low birth weight babies (VLBW, birth weight < 1500 g). 500 infants will be recruited from 10 centres in the UK and Europe. Babies will be randomised to receive a continuous insulin infusion (0.05 units/kg/h) or to receive standard neonatal care from the first day of life and for the next 7 days. If blood glucose (BG) levels fall infants will receive 20% dextrose titrated to maintain normoglycaemia (4-8 mmol/l). If BG is consistently above 10 mmol/l babies will receive standard treatment with additional insulin infusion. The primary end point will be mortality on or before expected date of delivery, secondary end points will be markers of morbidity and include episodes of sepsis, severity of retinopathy, chronic lung disease and growth.

Cancer risk following growth hormone use in childhood: implications for current practice.

The therapeutic use of growth hormone (GH) has caused concern, as it is anabolic and mitogenic, and its effector hormone, insulin-like growth factor (IGF)-I is anti-apoptotic. As both hormones can cause proliferation of normal and malignant cells, the possibility that GH therapy may induce cancer, increase the risk of tumour recurrence in those previously treated for a malignancy, or increase the risk of cancer in those with a predisposition, has resulted in concerns over its use. There are theoretical and epidemiological reasons that suggest GH and IGF-I may be important in tumour formation and proliferation. Malignant tumours have been induced in animals exposed to supraphysiological doses of GH, whereas hypophysectomy appears to protect animals from carcinogen-induced neoplasms. In vitro, proliferation and transformation of normal haemopoetic and leukaemic cells occurs with supraphysiological doses of GH, but not with physiological levels. IGF, IGF binding proteins (IGFBP) and IGFBP proteases influence the proliferation of cancer cells in vitro; however, GH is probably not involved in this process. Epidemiological studies have suggested an association between levels of IGF-I and cancer, and an inverse relationship between IGFBP-3 and cancer; however, these associations have been inconsistent. A number of studies have been undertaken to determine the risk of the development of cancer in children treated with GH, either de novo, or the recurrence of cancer in those previously treated for a malignancy. Despite early concerns following a report of a cluster of cases of leukaemia in recipients of GH, there appears to be no increased risk for the development of leukaemia in those treated with GH unless there is an underlying predisposition. Even in children with a primary diagnosis of cancer, subsequent GH use does not appear to increase the risk of tumour recurrence. However, a recent follow-up of pituitary GH recipients has suggested an increase in colorectal cancer. In addition, follow-up of oncology patients has suggested an increase in second neoplasms in those who also received GH therapy. These studies emphasise the importance of continued surveillance both internationally with established databases and also nationally through single-centre studies.

Growth hormone deficiency (GHD) from birth to 2 years of age: diagnostic specifics of GHD during the early phase of life.

The first 2 years of life represent a transition period when growth changes from predominantly growth hormone (GH) independent to GH dependent. In the fetus, growth is influenced by genetic and environmental factors in addition to nutrition and growth factors including insulin. In infancy, nutrition remains an important determinant of growth. GH levels are high in mid-gestation and at birth, then fall sharply for the first few weeks and more slowly over the next few months reaching pre-pubertal levels by around the age of 6 months. GH deficiency (GHD) may present at birth with hypoglycaemia, micropenis or prolonged conjugated hyperbilirubinaemia. Although length at birth is usually within the normal centile ranges, post-natal growth failure can begin early and be profound.

Improvements in final height over 25 years in growth hormone (GH)-deficient childhood survivors of brain tumors receiving GH replacement.

Final height (FH) outcome is important in survivors of childhood brain tumors. GH replacement is indicated in those found to be GH deficient (GHD). More recently, GnRH analogs (GnRHa) have been introduced to delay early or rapidly progressing puberty to allow more time for linear growth. Studies to FH are important to determine the effectiveness of growth-promoting strategies. Our aim was to assess whether evolving endocrine strategies have improved FH outcome and to determine whether GnRHa therapy has contributed auxologically. FH data were examined in 58 children (31 males and 27 females) with radiation-induced GHD who had been treated with GH. All had received a combination of cranial (CI; n = 17) or craniospinal (CSI; n = 41) irradiation with or without chemotherapy for a brain tumor. Eleven patients received GnRHa therapy. Throughout the 25 yr of the study patients came closer to achieving target height (i.e. a reduction in height loss), both those receiving CI (r = 0.5; P = 0.03) and those receiving CSI (r = 0.6; P < 0.001). The patients receiving GH therapy before 1988 compared with from 1988 onward had a similar age at irradiation [mean (+/-SD), 5.8 (3.0) vs. 6.2 (2.9) yr; P = 0.6], but experienced a more prolonged time interval from completing irradiation to starting GH [5.4 (2.4) vs. 3.3 (1.6) yr; P < 0.001]. Forward stepwise regression analysis revealed that height loss is affected by age at irradiation (P < 0.001), previous spinal irradiation (P = 0.02), chemotherapy (P < 0.001), and exposure to GnRHa therapy (P < 0.001). In the 11 patients treated with GnRHa therapy FH SD scores were improved compared with FH predictions calculated from a model derived from the patients not treated with GnRHa [-0.8 (1.6) vs. -2.4 (0.8) SD score; P < 0.001]. We have demonstrated an overall improvement in FH in children treated with GH for GHD after therapy for brain tumors over the last 25 yr. In the subset of children in whom the growth prognosis was adversely affected by early puberty, the combination of GnRHa and GH improved their prospects of achieving target height. The improved auxological outcome may reflect 1) the use of more standardized GH schedules and better dosing regimens, 2) a reduction in the time interval between finishing radiotherapy and receiving GH replacement, and 3) the use of GnRHa in addition to GH replacement in carefully selected patients.