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.

Problems with using total serum bilirubin as a criterion for phototherapy in extremely low-birthweight infants.

BACKGROUND: Despite the early use of phototherapy and exchange transfusion in premature infants based on total serum bilirubin (TSB), the reemergence of kernicterus has been reported. The aim of this study was to assess the validity of using TSB as the criterion for phototherapy in extremely low-birthweight infants (ELBWI). METHODS: We reviewed the medical charts of 43 ELBWI admitted to hospital between January 2009 and December 2010, and analyzed the relationship between TSB and unbound bilirubin (UB). RESULTS: No infant underwent exchange transfusion or developed acute bilirubin encephalopathy. There was a significant correlation between TSB and UB measured immediately before phototherapy during the first 7 days of life (r = 0.657, P < 0.001), but none thereafter (r = 0.120, P = 0.213). Thirty-seven percent of infants who underwent phototherapy during the first 7 days of life had suprathreshold USB but subthreshold TSB, whereas this rose to 97% thereafter. CONCLUSIONS: No correlation was observed between TSB and UB in ELBWI after the first 7 days of life, and almost all phototherapy sessions were initiated based on the UB criterion, even though TSB was below the accepted threshold. UB may be high if jaundice is evaluated solely on the basis of TSB.

Feeding interval and postprandial intestinal blood flow in premature infants.

BACKGROUND: The feeding interval is an important factor in enteral feeding of premature infants. We investigated postprandial intestinal blood flow in stable very-low-birthweight infants fed at 2-h and 3-h intervals. METHODS: We used pulsed wave Doppler ultrasound to measure blood flow velocity of the superior mesenteric artery (SMA) before feeding and at 15, 30, 45, and 60 min after feeding. Measurements were made on the day of starting enteral nutrition (1 or 2 days of age), and at 3 and 5 days of age. A total of 21 studies were performed in seven infants fed every 2 h, and 54 studies were performed in 18 infants fed every 3 h. RESULTS: In infants fed every 2 h, SMA blood flow velocity increased from before feeding to 30 min after feeding and then decreased at 60 min after feeding. In infants fed every 3 h, SMA blood flow velocity increased after feeding, reaching a peak at 30 min. The correlation coefficients between the volume of milk per feed and the postprandial increase in time-averaged mean blood flow velocity were 0.398 (P = 0.074, n = 21) and 0.597 (P = 0.000, n = 54) in infants fed at 2-h and 3-h intervals, respectively. CONCLUSIONS: SMA blood flow velocity significantly increased after feeding in infants fed at 2-h and 3-h intervals. The volume of milk per feed might affect the postprandial increase in SMA blood flow velocity.

Proinflammatory cytokinemia associated with transient myeloproliferative disorder in down syndrome.

A transient myeloproliferative disorder (TMD) occurs in 10% of the infants with Down syndrome. While most cases resolve within a few months, in 20% of them TMDs are life-threatening or fatal. We encountered 4 patients with TMD, including 1 patient who died of liver failure and disseminated intravascular coagulation. Suspecting involvement of proinflammatory cytokines, we serially assayed them in patients' sera. Cytokines were significantly more abundant in patients than in controls. Interleukins 1 and 2, tumor necrosis factor alpha, interferon gamma, and granulocyte-macrophage colony-stimulating factor were greatly increased, especially in the infant who died. Sustained cytokinemia is likely to participate in TMD pathophysiology, and very high serum concentrations might predict a poor outcome.

Oral iron supplementation in preterm infants treated with erythropoietin.

BACKGROUND: It is not known whether a moderate dose of oral iron supplementation would further enhance erythropoiesis in recombinant human erythropoietin (EPO)-treated very low-birthweight (VLBW) infants. METHODS: In total, 24 preterm infants with birthweights 750-1499 g were enrolled at the age of 14-28 days to receive 400 IU/kg per week EPO subcutaneously for 8 weeks. The infants were randomly allocated either to receive oral iron supplementation 4 mg/kg per day or to serve as controls. RESULTS: Hemoglobin and the absolute reticulocyte count in the iron supplementation and the control groups remained identical throughout the study period, whereas serum ferritin was significantly lower in the control group at study exit and follow up. Rates of treatment success (no need for transfusion and hemoglobin never below 8 g/dL) also did not differ between the groups. CONCLUSIONS: In this study we did not find a clear advantage in a moderate dose of oral iron supplementation on erythropoiesis in EPO-treated VLBW infants. Whether a higher dose would lead to enhanced erythropoiesis remains to be answered.

Inhibition of human eosinophil activation by a cysteinyl leukotriene receptor antagonist (pranlukast; ONO-1078).

Eosinophils produce cysteinyl leukotrienes such as leukotriene C4 and D4 upon stimulation by platelet-activating factor or other mediators, and these cells themselves express cysteinyl leukotriene receptors. Pranlukast, a compound developed in Japan, antagonizes cysteinyl leukotriene receptors and inhibits contraction of airway smooth muscle, microvascular leakage into airways, and eosinophil infiltration. This agent can decrease symptoms of bronchial asthma, but its specific influences on effector functions of eosinophils important to the pathogenesis and exacerbation of asthma remain unknown. In the present study, we investigated the effect of pranlukast on human eosinophil functions. Eosinophils obtained from peripheral blood of normal volunteers were stimulated by platelet-activating factor, leukotriene D4, or phorbol ester. Superoxide anion generation was measured by reduction of cytochrome c. Expression of alphaMbeta2 was analyzed by flow cytometry. To evaluate eosinophil degranulation, eosinophil protein X, a toxic granule constituent, was measured by radioimmunoassay in sample supernatants. Pranlukast partially inhibited major eosinophil effector functions of superoxide anion generation and degranulation induced by platelet-activating factor, although at concentrations tested pranlukast failed to significantly reduce platelet-activating factor-induced alphaMbeta2 expression. Pranlukast completely inhibited leukotriene D4-induced superoxide generation and alphaMbeta2 expression. In contrast, pranlukast at 10(-6)M did not affect phorbol ester-induced superoxide generation at 120 minutes, degranulation, or alphaMbeta2 expression. The results suggested that inhibition by pranlukast of platelet-activating, factor-induced eosinophil effector functions such as superoxide generation and degranulation might result at least partly from antagonism of autocrine mechanisms involving cysteinyl leukotrienes produced in response to platelet-activating factor.

Distinct isoforms of protein kinase C are involved in human eosinophil functions induced by platelet-activating factor.

BACKGROUND: Platelet-activating factor (PAF) is a potent stimulator of eosinophils. Recently, treatment with a protein kinase C (PKC) inhibitor which generally inhibits PKC isoforms has been shown to modulate several eosinophil functions in distinct manners, in that PKC inhibition enhanced CD11b expression and cellular adhesion, but inhibited superoxide generation and degranulation in PAF-stimulated human eosinophils. These results suggested that distinct PKC isoforms were likely to be involved in each eosinophil function induced by PAF. We have therefore investigated whether or not the PKC isoforms involved in PAF-induced CD11b expression and superoxide generation were different. METHODS: Human eosinophils prepared from healthy volunteers were treated with PKC inhibitors, bis-indolylmaleimide I (BisI; a general PKC inhibitor), myristoylated PKC inhibitor peptide (myr-psiPKC; a PKCalpha, beta and delta inhibitor) and rottlerin (a PKCdelta inhibitor), followed by stimulation with PAF. CD11b expression was determined using flow cytometry and superoxide generation was evaluated using a cytochrome c reduction assay. RESULTS: BisI treatment led to enhancement of PAF-induced CD11b expression, while myr-psiPKC and rottlerin did not. In contrast, PAF-induced superoxide generation was inhibited by treatment with BisI, myr-psiPKC and rottlerin. CONCLUSIONS: PKCalpha, beta and delta are not involved in PAF-induced CD11b expression, but PKCdelta is involved in the PAF-induced activation of superoxide anion generation.

Cellular adhesion is required for effector functions of human eosinophils via G-protein coupled receptors.

BACKGROUND: Eosinophils play an important role in the pathogenesis of allergic diseases. Chemoattractants, including platelet-activating factor (PAF) and complement component 5a (C5a), induce eosinophil infiltration and promote eosinophil effector functions. OBJECTIVE: To compare eosinophil degranulation and superoxide anion (O2-) generation induced by various chemoattractants, and to elucidate the role of cellular adhesion on these effector functions. METHODS: Human eosinophils were stimulated with PAF, C5a, eotaxin, or leukotriene B4 (LTB4). O2- generation was assayed by a chemiluminescence method using a Cypridina luciferin analog as the amplifier. Degranulation and adhesion were measured by quantitating eosinophil protein X by radioimmunoassay. Expression of CD11b on eosinophils was measured by flow cytometry. RESULTS: PAF and C5a induced significant degranulation and O2- generation from eosinophils. In contrast, the potency of eotaxin or LTB4 for these functions was much less. PAF and C5a also significantly enhanced eosinophil adhesion, whereas eotaxin and LTB4 did not. CD11b expression on eosinophils was enhanced by all four stimulants, and the order of potency to induce CD11b expression was C5a > PAF > eotaxin > LTB4. CONCLUSIONS: The potency of PAF and C5a for inducing effector function in eosinophils was greater than that of eotaxin or LTB4. The magnitude of the effector function was consistent with the degree of eosinophil adherence induced by each stimulant. These results suggest that effector functions of eosinophils which are mediated through G-protein coupled receptors are dependent on cellular adhesion.

Fenoterol inhibits superoxide anion generation by human polymorphonuclear leukocytes via beta-adrenoceptor-dependent and -independent mechanisms.

BACKGROUND: Beta2-adrenoceptor agonists, used widely as bronchodilator in treating bronchial asthma, may have anti-inflammatory activity. OBJECTIVE: We examined whether various widely prescribed beta2-adrenoceptor agonists differ in anti-inflammatory mechanisms. METHODS: We investigated effects of these drugs on superoxide anion generation by stimulated human polymorphonuclear leukocytes in vitro using chemiluminescence. RESULTS: At high concentrations, fenoterol significantly inhibited both N-formylmethionyl-leucyl-phenylalanine- and phorbol myristate acetate-induced superoxide generation by neutrophils. In contrast, salbutamol or procaterol partially inhibited generation with the former stimulus but not the latter. Inhibition by salbutamol or procaterol was completely reversed by either propranolol, a nonselective beta-adrenoceptor antagonist, or ICI-118551, a beta2-adrenoceptor-selective antagonist. In contrast, the effect of fenoterol at concentrations exceeding 10(-6) M against superoxide generation with the former stimulus was only partially reversed by antagonists, and the effect of high concentrations of fenoterol against generation with the latter stimulus was not reversed. No drugs scavenged superoxide at the highest concentration used (10(-5) M). CONCLUSIONS: Fenoterol at high concentrations has an inhibitory effect on superoxide generation that includes a component not mediated via beta2-adrenoceptors. Direct inhibition at or downstream from protein kinase C may be involved.