Prevalence and Risk Factor for Antibiotic-resistant Escherichia coli Colonization at Birth in Premature Infants: A Prospective Cohort Study.

BACKGROUND: Escherichia coli causes neonatal early-onset sepsis (EOS) that is associated with high mortality and increasing antibiotic resistance. Thus, we estimated the prevalence, antibiotic susceptibility and risk factors for colonization of E. coli in premature infants at birth and characterized the pathogenicity of the isolates. METHODS: A prospective surveillance study was conducted at three Japanese perinatal centers between August 2014 and February 2017. Infants weighing <2 kg and/or at gestational age <35 weeks at birth were enrolled. We screened the mothers and neonates for E. coli colonization. Pulsed-field gel electrophoresis was used to analyze the relatedness between the maternal and neonatal isolates. Virulence factors for the isolates were determined using polymerase chain reaction. RESULTS: We enrolled 421 premature infants born to 382 mothers. The rate of colonization in mothers was 47.6%, comprising 5.9% extended-spectrum beta-lactamase-producing E. coli (ESBL-E) and 20.0% ampicillin-resistant strains. Ten (2.4%) infants exhibited colonization; ESBL-E and ampicillin-resistant strains colonized three and four infants, respectively. Three antibiotic-resistant, strain-positive infants developed EOS. Pulsed-field gel electrophoresis revealed vertical transmission of bacteria in four infants. Multivariate logistic regression analysis revealed that ESBL-E-positive mothers [odds ratio (OR), 19.2; 95% confidence interval (CI), 2.5-145.7)] and vaginal delivery (OR, 9.4; 95% CI, 1.7-50.7) were risk factors for neonatal colonization. The infant isolates possessed numerous virulence factors. CONCLUSIONS: Although the prevalence of E. coli-colonized premature infants at birth was low, the rate of antibiotic resistance and the attack rate for EOS were high. Infants with ESBL-E positive mothers should be closely monitored for EOS.

Maximal sterile barrier precautions independently contribute to decreased central line-associated bloodstream infection in very low birth weight infants: A prospective multicenter observational study.

BACKGROUND: The use of peripherally inserted central catheters (PICCs) in neonates differs among various institutions and countries because there are no random controlled trials or large observational studies regarding maximal sterile barrier (MSB) precautions in neonatal intensive care units. Our objective was to investigate the association of MSB implementation with central line-associated bloodstream infection (CLABSI) in very low birth weight infants. METHODS: This was a prospective multicenter observational study in Japan of infants with birth weight less than 1501 grams and in whom a PICC was placed for the first time between October 2014 and March 2017. Risk factors for CLABSI, both related and unrelated to MSB, were assessed by the mixed-effects Cox proportional hazards model, with the neonatal center variable as the random effect. RESULTS: In total, 33,713 catheter-days among 2383 infants were included. We observed 70 cases of CLABSI. MSB precautions were implemented in 13.9% of insertions and were associated with a lower CLABSI risk (adjusted hazard ratio, 0.20; 95% confidence interval, 0.05-0.84). CONCLUSIONS: We found that MSB implementation during PICC insertion in infants with birth weight less than 1501 grams independently contributed to a decrease in CLABSI risk.

Complications of peripherally inserted central venous catheter in Japanese neonatal intensive care units.

BACKGROUND: The aim of this study was to investigate the incidence and risk factors of peripherally inserted central venous catheter (PICC)-related complications using a multicenter case survey. METHOD: A prospective cohort study was carried out by 19 neonatal intensive care units (NICUs) in Japan from February 2005 to March 2007. A total of 975 case records were collected. PICC-related complications including pericardial effusion/cardiac tamponade pleural effusion/ascites, catheter removal difficulties, catheter-related bloodstream infection (CR-BSI), and symptomatic catheter-related thrombosis were collected from case record forms. As for precautions during insertion, institutions were classified into three groups: those with maximum barrier precautions; standard precautions; and no specific precautions. RESULTS: PICC complications occurred in 27 cases (2.9%) among 946 PICC. The incidence was 1.6% for CR-BSI, and 0.1% for cardiac tamponade. CR-BSI rate per 1000 catheter-days was 1.1 with maximum barrier precautions at catheter insertion, 1.2 with standard precautions, and 1.8 with no specific precautions. Multiple logistic regression analysis showed that proximal placement (odds ratio [OR], 3.88; 95% confidence interval [CI]: 1.42-10.60, P = 0.008) and longer placement duration (OR, 1.35; 95%CI: 1.14-1.60, for each week, P = 0.0005) independently contributed to overall complications. CONCLUSION: The incidence of cardiac tamponade was rare in this multicenter prospective study. Longer duration and proximal placement may be risk factors for PICC complications. In this cohort, the CR-BSI rate was low irrespective of the degree of barrier precautions at insertion.

Lack of transient receptor potential vanilloid-1 enhances Th2-biased immune response of the airways in mice receiving intranasal, but not intraperitoneal, sensitization.

BACKGROUND: Transient receptor potential vanilloid-1 (TRPV1) may modulate allergic airway inflammation because it is expressed not only on the nerve endings but also on several cells of the immune system. We wanted to know the characteristics of airway and systemic responses against sensitization and challenge with allergens in TRPV1 receptor gene knockout mice (TRPV1(-/-)). METHODS: TRPV1(-/-) and their wild-type counterparts (TRPV1(+/+)) were sensitized with either house dust mite (HDM) or ovalbumin (OVA) via intranasal (i.n.) or intraperitoneal (i.p.) route before the final i.n. challenge with the corresponding allergen. One day after the final challenge, serum IgE levels, cytokine levels in the bronchoalveolar lavage fluid (BALF), and the number of BALF cells were examined after measuring bronchial hyperresponsiveness against methacholine. RESULTS: Compared to TRPV1(+/+), TRPV1(-/-) showed enhanced Th2-biased response after i.n. HDM or OVA sensitization, including increased levels of serum IgE, interleukin 4 (IL-4) and eosinophils in the BALF. By contrast, when sensitized via i.p. route, the response against OVA or HDM was almost similar between TRPV1(+/+) and TRPV1(-/-). CONCLUSION: TRPV1 receptor may downregulate Th2-biased immune response when sensitized via airways, although this was not the case when sensitized systemically.

Periventricular echodensity measured with the integrated backscatter system: from a qualitative assessment to a quantitative approach.

BACKGROUND: The degree of periventricular white matter echodensity in preterm infants has been utilized as a sign of the early ultrasonographic appearance of periventricular leukomalacia, and this has been called periventricular echodensity (PVE). OBJECTIVES: The aim of this study was to quantitatively measure PVE utilizing a new method which is called calibrated integrated backscatter (calibrated IB). METHODS: Eighty-eight preterm infants (extremely low birth weight infants, n = 17; very low birth weight infants, n = 26; low birth weight infants, n = 45) without any CNS abnormality were enrolled. IB is the returned sound pressure against supersonic waves sent from an ultrasonographic machine. The IB of the choroid plexus and periventricular white matter in the subrolandic area were measured on a parasagittal cerebral image. The degree of PVE was defined by subtracting the IB of the choroid plexus from that of the periventricular white matter in the subrolandic area (calibrated IB of PVE). RESULTS: The intraobserver and interobserver correlations were both excellent (between 0.87 and 0.98 as correlation coefficients). There was a trend for the calibrated IB of PVE to decrease in accordance with time after birth, with a significant difference in very low birth weight and low birth weight infants. CONCLUSIONS: The objectively measured brightness of PVE was comparable to that of the choroid plexus irrespective of the size of the infants. Measurement of the calibrated IB of PVE might be a reliable method to assess PVE.

Hepatocyte growth factor treatment improves alveolarization in a newborn murine model of bronchopulmonary dysplasia.

BACKGROUND: Bronchopulmonary dysplasia (BPD) is thought to be one form of developmental arrest of the lung. Hepatocyte growth factor (HGF) participates in normal lung growth and in lung regeneration. OBJECTIVES: The purpose of this study is to investigate whether HGF can improve alveolarization and attenuates functional abnormalities of a murine model of BPD induced by hyperoxia. METHODS: Three-day-old CD-1 mice were exposed to 90% of oxygen or room air (control group) for 7 days. These animals were then kept in room air for the next 7 days. Recombinant human (rh) HGF (100 microg/g b.w., divided 3 times, rhHGF group) or vehicle (vehicle group) was administered intraperitoneally during hyperoxia. On day 17, the pulmonary function test and bronchial hyperresponsiveness (BHR) were examined. Mean linear intercepts (MLI) were measured as parameters of alveolarization. Cell renewal (on day 10) and vascularization of the lung were also evaluated. RESULTS: Exposure to hyperoxia induced increased airway resistance and BHR. These animals showed a severely simplified alveolar structure, increased MLI, decreased cell renewal (16.1 +/- 2.4 vs. 29.6 +/- 2.4%, p < 0.05), and decreased vascularization (15.1 +/- 0.3 vs. 18.4 +/- 1.5 vessels/hpf, p < 0.05, vehicle vs. control group, respectively). rhHGF treatment during exposure to hyperoxia significantly reduced all of these changes (27.9 +/- 1.7%, 18.2 +/- 0.5 vessels/hpf for cell renewal and vascularization, respectively; all values are p < 0.05 against vehicle animals). CONCLUSION: HGF partially protects against the inhibition of alveolarization and improves functional abnormality in the hyperoxia-induced neonatal mice model of BPD.

Complications of percutaneously inserted central venous catheters in Japanese neonates.

BACKGROUND: To determine institutional policies concerning percutaneously inserted central venous catheter (PICC) utilization and also frequencies of complications such as pericardial effusion (PCE), cardiac tamponade (CT), pleural effusion, ascites, venous thrombosis, and catheter removal difficulties. METHODS: Nationwide postal questionnaire survey was carried out that included institutional policies on PICC and numbers of complications recorded from January 1999 to December 2003. RESULTS: A total of 98 replies were received from 193 neonatal intensive care units (NICU) in Japan. As a catheter tip location, positions outside of the heart were highly preferred, while only 9% accepted a right atrial position. Twenty-eight cases of PCE or CT were reported, representing an estimated frequency of 0.07-0.11% of PICC insertions. Pleural effusion/ascites and removal difficulties (36 and 35 cases, respectively) were encountered in approximately 0.09-0.14% of insertions. CONCLUSIONS: Frequency of PCE/CT appeared comparable to previously reported occurrences. Also, pleural effusion/ascites and removal difficulty appeared to be rare complications.

Age-related difference in the persistency of allergic airway inflammation and bronchial hyperresponsiveness in a murine model of asthma.

AIM: Asthmatic children are more likely to outgrow their symptoms than adult patients. Thus, we wanted to know whether there were any age-related differences in the time course of the allergic airway inflammation. METHODS: BALB/C mice at different ages (young: 3 days after birth, and mature: 8 weeks of age) were sensitized with ovalbumin (OVA). Subsequently, animals were challenged with aerosolized OVA during 1, 2, 4 or 8 consecutive weeks. Bronchial hyperresponsiveness (BHR), serum IgE levels, the degrees of inflammatory cell infiltration (ICI) and goblet cell metaplasia (GCM) in the airways, and the number of eosinophils and cytokine levels in bronchoalveolar lavage fluid (BALF) were examined. RESULTS: At 1 week, airway inflammation and BHR occurred similarly between young and mature mice. However, BHR disappeared at 4 weeks in young, whereas it persisted even at 8 weeks in mature mice. GCM, ICI and eosinophilia in BALF attenuated with time, with more remarkable reduction in young mice. The BALF IL-4 level was high during the first 2 weeks in both groups, while the IL-2 level was significantly increased at 2 weeks solely in young mice. CONCLUSION: Different time courses in airway inflammation and in BHR may relate to the different prognoses between childhood and adult asthma. The understanding of the mechanisms underlying this age-related differences may be helpful to induce remission in asthmatic patients.

Effect of disodium cromoglycate on airway mucus secretion during antigen-induced late asthmatic responses in a murine model of asthma.

BACKGROUND: Disodium cromoglycate (DSCG) is known to inhibit both immediate and late asthmatic responses (IAR and LAR). However, its effect on mucus hypersecretion is unknown. Using a murine model of asthma, we aimed to determine whether mucus secretion increased during IAR and LAR. We also studied the potency of DSCG in inhibiting mucus secretion and on airway eosinophilia. METHODS: Mice were subjected to initial intraperitoneal sensitization and airway challenge to ovalbumin (OVA) and then provoked by additional exposure to OVA. Some mice were pretreated with aerosolized DSCG (20 mg/ml) 1 h before the provocation with OVA. After serial measurements of enhanced pause (Penh), an indicator of airflow obstruction, serum samples and bronchoalveolar lavage fluids (BALF) were collected. Then, the lungs were excised and a morphometric analysis for mucus hypersecretion was performed. RESULTS: A biphasic increase in Penh (IAR and LAR) was observed in sensitized animals after provocation with OVA. Airway eosinophilia was observed during both responses. Intraluminal mucus significantly increased during LAR, but not during IAR. DSCG significantly attenuated both IAR and LAR, and significantly inhibited the increase in intraluminal mucus during LAR, but had no effect on eosinophilia in BALF. CONCLUSION: Our results suggest that airway hypersecretion may be involved as a component of airflow obstruction during LAR, and that this is unlikely during IAR. DSCG may be effective in reducing excessive airway mucus caused by exposure to allergens.

Characteristic features of allergic airway inflammation in a murine model of infantile asthma.

BACKGROUND: The pathophysiology of infantile asthma may differ from that in older children or in adults, partly because of the different immune response depending upon maturation. In adult mice, the sensitizing dose of antigen is known to be critical to the polarized development of helper T cell subsets and allergic airway inflammation. We wanted to know the characteristics of allergic airway inflammation of infantile asthma by developing a murine model. METHODS: BALB/C mice at different stages of maturation (juvenile: 3 days after birth; adult: 8 weeks of age) were sensitized with 10 or 1,000 microg ovalbumin (OVA) or vehicle. The animals were then challenged with aerosolized OVA or saline once a day during 6 consecutive days. After the final challenge, bronchial hyperresponsiveness (BHR), bronchoalveolar lavage fluid (BALF), histological changes in the airways and immunological status were examined. RESULTS: In both juvenile and adult animals, sensitization with 10 microg OVA induced the T helper 2 response (elevated IL-4 and decreased IFN-gamma levels). BHR, airway eosinophilia, the inflammatory cell infiltration, goblet cell metaplasia (GCM), and IgE antibody production were more prominent in animals given this dose than 1,000 microg OVA. Among these responses, GCM as well as BALF IL-4, and BHR were comparable between juvenile and adult animals, whereas other parameters were lower in juvenile animals, especially in those given 1,000 microg OVA. CONCLUSION: GCM and, consequently, airway mucus hypersecretion may be an important component of allergic airway inflammation in infantile asthma.

Purification, crystallization and preliminary X-ray diffraction studies on pyruvate phosphate dikinase from maize.

Pyruvate phosphate dikinase (PPDK) from maize catalyzes the reversible conversion of ATP, orthophosphate and pyruvate to AMP, pyrophosphate and PEP. In higher plants, this enzyme is believed to be involved in the C(4) dicarboxylic acid pathway. PPDK was crystallized by the vapour-diffusion method using polyethylene glycol as a precipitant. The crystals belong to the orthorhombic space group C2, with unit-cell parameters a = 108.2, b = 100.2, c = 108.4 A, beta = 96.5 degrees, and diffract to 2.3 A using SPring-8 synchrotron radiation.

Immediate control of a methicillin-resistant Staphylococcus aureus outbreak in a neonatal intensive care unit.

An outbreak of methicillin-resistant Staphylococcus aureus (MRSA) colonization occurred from November 2001 in the neonatal intensive care unit (NICU) of our hospital. Since the establishment of our NICU in 1991, some MRSA has been detected in NICU patients. For MRSA infection preventive measures, utilization of the following items was implemented: mupirocin ointment, diluted povidone iodine, methylrosaniline chloride, and disposable rubber gloves. Patients in whom MRSA was detected received intranasal administration of the mupirocin ointment three times daily and were bathed in, or their entire body was wiped with diluted povidone iodine once daily for the first 3 days in each week. In addition, they received an intraoral application of methylrosaniline chloride daily. All therapy was done until MRSA strains were undetectable for 3 continuous weeks. Genotypes of 13 MRSA strains isolated from eight inpatients and one mother were analyzed by pulsed-field gel electrophoresis (PFGE). All PFGE patterns were identical, except for one, which had one distinct migrating fragment. These data suggested that this MRSA outbreak was caused by the same strain, which was derived from the mother of a low-birth-weight infant born on October 30, 2001. Gradually, the number of inpatients carrying MRSA decreased, until finally MRSA was no longer observed, in April 2002. Fortunately, we controlled the MRSA outbreak immediately, and none of the inpatients developed severe MRSA infection. We think that in our NICU, which is isolated from other hospital wards, it is important to prevent the entrance of MRSA-carrying mothers.

Airway responsiveness and airway remodeling after chronic exposure to procaterol and fenoterol in guinea pigs in vivo.

BACKGROUND: Chronic exposure to fenoterol (FEN), a beta(2)-adrenergic receptor (beta(2)-AR) agonist, was shown to induce both airway hyperresponsiveness and airway remodeling in experimental animals. OBJECTIVE: We wanted to know the effects of chronic exposure to procaterol (PRO), a beta(2)-AR agonist, on airway function and structure, because this agent is widely used as a bronchodilator in Japan. For comparison, the effects of FEN were also examined. METHODS: Aerosolized PRO (0.1 or 1 mg/ml), FEN (1 mg/ml) or vehicle (0.9% NaCl) was given to guinea pigs 3 times a day for 6 weeks. Sublaryngeal deposition of these agents was calculated using radioisotopes. At 72 h after the last inhalation of PRO, FEN or vehicle, the dose-response relationship between lung resistance (R(L)) and intravenously administered acetylcholine (ACh) was measured. After measuring R(L), histological changes in noncartilaginous airway dimensions were evaluated. RESULTS: The amount of sublaryngeal deposition of 0.1 mg/ml PRO in the present study was speculated to be 100 times larger than that of therapeutic dose. ACh concentrations causing 2-fold, 10-fold and maximal increases in R(L) were not different in 4 groups tested. In the smaller membranous airways (<0.4 mm in diameter), but not the larger ones, thickening of adventitial areas was significantly greater in animals treated with beta(2)-AR agonists than in control animals (23 and 25, and 96% higher in animals treated with 0.1 and 1 mg/ml PRO or 1 mg/ml FEN, respectively). The degree of the increase was significantly less in PRO-treated animals than in FEN-treated animals (p < 0.01). CONCLUSION: Our results did not provide any evidence that regular inhalation of PRO at the therapeutic dose might induce bronchial hyperresponsiveness. In addition, huge amounts of PRO only caused a mild thickening of the adventitial areas, suggesting that PRO may be a weak inducer of airway remodeling compared with FEN.

Role of a conserved J8/7 X P4 base-triple in the Tetrahymena ribozyme.

The Tetrahymena group I intron ribozyme folds into a complex three dimensional structure for performing the self-splicing reaction. Catalysis depends on its core structure comprising two helical domains, P4-P6 and P3-P7. The two domains are joined by three sets of conserved base-triple(s) and other tertiary interactions. We found that the disruption of J8/7 X P4, one such conserved base-triple, causes the catalytic ability to deteriorate without altering the folding rate. This suggests that the base-triple stabilizes the active structure of the ribozyme but plays no significant role in RNA folding. By combining the present and previous results, it can be concluded that three sets of conserved base-triples play distinct roles in the Tetrahymena ribozyme.

Maturational changes in airway remodeling after chronic exposure to ovalbumin in sensitized guinea pigs: role of cell renewal of airway resident cells.

We wanted to know whether airway remodeling caused by chronic exposures to antigen differed depending on the degree of maturation of animals. We sensitized guinea pigs at different stages of maturation: juvenile (approximately 200 g in body weight), adult (400 g), and old animals (800 g). Then, animals were repeatedly challenged with inhaled ovalbumin (0.3% or 3%) or vehicle twice a week for 6 wk. After the final challenge, the lungs were excised for the histologic evaluation of changes in the thickness of the inner wall area (Ti), the smooth muscle area (Tm), and the outer wall area (To) in noncartilaginous airway dimensions. To clarify whether or not the observed changes were due to renewal of airway cells, we stained the samples with labeled nucleotide 5'-bromo-2'-deoxyuridine (BrdU), which we injected repeatedly during the challenge periods. Chronic exposures to antigen induced airway wall thickening regardless of their stages of maturation. However, prominent areas of thickening differed between the three groups. Ti increased more remarkably in juvenile and adult animals than in old ones. By contrast, Tm significantly increased only in old animals. BrdU staining revealed more renewal of epithelial cells in juvenile and adult animals than in old ones (juvenile >or=adult > old), suggesting that increased renewal of epithelial cells contributed to the thickening of Ti in juvenile and adult animals. By contrast, only a slight increase in smooth muscle cell renewal was found even in old animals, indicating that an increase in Tm was due to factors such as hypertrophy. These results show that the development of antigen-induced airway remodeling is partly modified by the degree of maturation of animals in vivo.

Mispaired P3 region in the hierarchical folding pathway of the Tetrahymena ribozyme.

BACKGROUND: The Tetrahymena group I ribozyme folds into a complex three-dimensional structure for performing catalytic reactions. The catalysis depends on its catalytic core consisting of two helical domains, P4-P6 and P3-P7, connected by single stranded regions. In the folding process, most of this ribozyme folds in a hierarchical manner in which a kinetically stable intermediate determines the overall folding rate. RESULTS: Although the nature of this intermediate has not yet been elucidated, a mispaired P3 stem (alt-P3) appears a likely candidate. To examine the effects of the alt-P3 structure on the kinetic and thermodynamic properties of the active structure of the ribozyme or its P3-P7 domain formation, we prepared and analysed variant ribozymes in which relative stabilities of the original P3 and alt-P3 structure were altered systematically. CONCLUSION: The results indicate that the alt-P3 structure is not the major rate-limiting factor in the folding process.

Efficacy of phenytoin against hyponatremic seizures due to SIADH after administration of anticancer drugs in a neonate.

A neonate with the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) developed refractory hyponatremic seizures following administration of anticancer drugs. The seizures did not respond to diazepam, phenobarbital, or lidocaine, but resolved immediately with administration of phenytoin. The low water-excretion capacity in neonates should be taken into consideration when fluid loading is attempted, to avoid renal damage upon administration of drugs such as cisplatin that have a potential damaging effect on the kidney. Phenytoin could be the therapy of choice for SIADH and resulting seizures in the neonatal period.

Effect of inhaled indomethacin on distilled water-induced airway epithelial cell swelling.

We evaluated the mechanism of the anti-asthmatic effect of inhaled indomethacin (Indo) by using an animal model (guinea pigs) of airway inflammation. After being exposed to either ozone or room air at identical flow rates (5 l/min) for 2 h, guinea pigs were anesthetized, tracheostomized, and lung resistance (RL) was subsequently measured. Guinea pigs inhaled either saline or Indo (1.5 mg/ml) for 1 min before undergoing an ultrasonically nebulized distilled water (UNDW) inhalation test. RL increased significantly after 10 min of UNDW inhalation in the room air and ozone groups but more so in the ozone group. This increase in RL was significantly suppressed by pretreatment with Indo. In the morphometric assessment of airway mucosa, a significant swelling of the epithelial cells after UNDW inhalation was observed in both the room air and ozone groups but especially so in the ozone group. This increase was also suppressed with Indo pretreatment. These results suggest that the increase in RL and the swelling of airway epithelial cells induced by inhaled UNDW in ozone-exposed guinea pigs was suppressed by pretreatment of inhaled Indo and that this suppression may be one of the reasons for the anti-asthmatic effect of inhaled Indo.