Cathy Hammerman

Safety assessment of probiotics for human use

The safety of probiotics is tied to their intended use, which includes consideration of potential vulnerability of the consumer or patient, dose and duration of consumption, and both the manner and frequency of administration. Unique to probiotics is that they are alive when administered, and unlike other food or drug ingredients, possess the potential for infectivity or in situ toxin production. Since numerous types of microbes are used as probiotics, safety is also intricately tied to the nature of the specific microbe being used. The presence of transferable antibiotic resistance genes, which comprises a theoretical risk of transfer to a less innocuous member of the gut microbial community, must also be considered. Genetic stability of the probiotic over time, deleterious metabolic activities, and the potential for pathogenicity or toxicogenicity must be assessed depending on the characteristics of the genus and species of the microbe being used. Immunological effects must be considered, especially in certain vulnerable populations, including infants with undeveloped immune function. A few reports about negative probiotic effects have surfaced, the significance of which would be better understood with more complete understanding of the mechanisms of probiotic interaction with the host and colonizing microbes. Use of readily available and low cost genomic sequencing technologies to assure the absence of genes of concern is advisable for candidate probiotic strains. The field of probiotic safety is characterized by the scarcity of studies specifically designed to assess safety on the one hand contrasted with the long history of safe use of many of these microbes in foods on the other hand.

Ductal Closure With Paracetamol: A Surprising New Approach to Patent Ductus Arteriosus Treatment

Standard pharmacologic closure of the patent ductus arteriosus currently involves the administration of 1 of 2 cyclooxygenase inhibitors: either indomethacin or ibuprofen. However, both of these drugs can be associated with potentially significant adverse effects. We present here the cases of 5 preterm infants (gestational age: 26–32 weeks; postnatal age: 3–35 days) with large, hemodynamically significant patent ductus arteriosus who had either failed or had contraindications to ibuprofen therapy. Each of these infants was treated with off-label oral paracetamol (15 mg/kg per dose every 6 hours). Ductal closure was achieved within 48 hours in all the treated infants. No toxicity was observed.

Neonatal Hyperbilirubinemia in Glucose-6-Phosphate Dehydrogenase-deficient Heterozygotes

Objectives. We assessed the incidence of hyperbilirubinemia, defined as serum total bilirubin ≥15 mg/dL (256 μmol/L), in a cohort of Sephardic Jewish female neonates at risk for glucose-6-phosphate dehydrogenase (G-6-PD) deficiency with especial emphasis on the heterozygotes. We studied the roles of hemolysis by blood carboxyhemoglobin (COHb) determinations and of the variant promoter of the gene for the bilirubin-conjugating enzyme uridine 5′-diphosphate glucuronosyltransferase 1 (UGT1A1) seen in Gilberts syndrome in the pathogenesis of the hyperbilirubinemia. Methods. Consecutively born, healthy, term, female neonates were screened for G-6-PD deficiency and observed clinically with serum bilirubin evaluations as indicated for hyperbilirubinemia. On day 3, blood was sampled for COHb, total hemoglobin (tHb), and a mandatory serum bilirubin determination. COHb, determined by gas chromatography, was expressed as percentage of tHb and corrected for inspired carbon monoxide (COHbc). DNA was analyzed for the G-6-PD Mediterranean563T mutation and for the variant UGT1A1 gene. Results. The cohort included 54 G-6-PD-deficient heterozygotes, 19 deficient homozygotes, and 112 normal homozygotes. More heterozygotes (12/54, 22%; relative risk: 2.26; 95% CI: 1.07–4.80) and deficient homozygotes (5/19, 26.3%; relative risk: 2.68; 95% CI: 1.05–6.90) developed hyperbilirubinemia, than did normal homozygotes (11/112, 9.8%). Third-day serum bilirubin values that were obtained from 144 neonates were significantly higher in both heterozygotes (11.2 ± 3.7 mg/dL [192 ± 64 μmol/L]) and G-6-PD-deficient homozygotes (12.0 ± 3.0 mg/dL [206 ± 52 μmol/L]) than in the G-6-PD normal homozygotes (9.4 ± 3.4 mg/dL [160 ± 58 μmol/L). In contrast, COHbc values were higher only in G-6-PD-deficient homozygotes (0.74% ± 0.14%) and not in heterozygotes (0.69% ± 0.19%, not statistically significant), compared with control values (0.63% ± 0.19%). High COHbc values were not a prerequisite for the development of hyperbilirubinemia in any of the G-6-PD genotypes. A greater incidence of hyperbilirubinemia was found among the G-6-PD-deficient heterozygotes, who also had the variant UGT1A1 gene, in both heterozygous (6/20, 30%) and homozygous (4/8, 50%) forms, than was found in their counterparts with the normal UGT1A1 gene (2/26, 7.7%). This effect was not seen in the G-6-PD normal homozygote group. A color reduction screening test for G-6-PD deficiency identified only 20.4% (11/54) of the heterozygotes. Conclusions. We showed that G-6-PD-deficient heterozygotes, categorically defined by DNA analysis, are at increased risk for neonatal hyperbilirubinemia. The screening test that was used was unable to detect most heterozygotes. Increased bilirubin production was not crucial to the development of hyperbilirubinemia, but presence of the variant UGT1A1 gene did confer increased risk. bilirubin, carbon monoxide, carboxyhemoglobin, females, gas chromatography, Gilberts syndrome, glucose-6-phosphate dehydrogenase deficiency, hemolysis, hyperbilirubinemia, neonates, polymerase chain reaction, Sephardic Jews, screening test, uridine 5′-diphosphate glucuronosyltransferase.

Procalcitonin in preterm infants during the first few days of life: introducing an age related nomogram

Objective: To determine normal concentrations of procalcitonin in preterm infants shortly after birth and to assess its accuracy in detecting bacterial infection. Methods: Blood samples of 100 preterm infants were prospectively drawn during the first 4 days of life for determination of procalcitonin concentration. Infants were classified into four groups according to their sepsis status. Results: Mean (SD) gestational age and birth weight were 32 (2.9) weeks and 1682 (500) g respectively. A total of 283 procalcitonin concentrations from healthy infants were plotted to construct nomograms of physiologically raised procalcitonin concentration after birth, stratified by two groups to 24–30 and 31–36 weeks gestation. The peak 95th centile procalcitonin concentration was plotted at 28 hours of age; values return to normal after 4 days of life. Only 12 infants were infected, and 13 of their 16 procalcitonin concentrations after birth were higher than the 95th centile, whereas samples taken at birth were lower. In a multivariable analysis, gestational age, premature rupture of membrane, and sepsis status influenced procalcitonin concentration independently, but maternal infection status did not. Conclusions: The suggested neonatal nomograms of preterm infants are different from those of term infants. Procalcitonin concentrations exceeding the 95th centile may be helpful in detecting congenital infection, but not at birth.

Safety of probiotics: comparison of two popular strains

#### Summary points Mounting clinical evidence shows that nutritional supplements of live micro-organisms (probiotics) have health advantages to humans. The appeal of probiotic therapy lies in the fact that it not only represents a non-invasive attempt to recreate natural flora rather than a disruption of nature, but it is also an approach that is both cheap and effective. However, the concept of willingly ingesting live bacteria remains somewhat counterintuitive. Although probiotic therapy is generally considered harmless, rare reports of systemic infections involving probiotic bacteria have raised clinical concerns. We therefore conducted a scientific review of the safety of these organisms. For the purpose of this review, we assumed therapeutic effectiveness and concentrated primarily on evaluating the safety of this treatment. Although many such reviews exist, previous authors have taken a uniform approach—they have mostly reported anecdotal case reports of infection or infection rates with the strain under investigation and then generalised their findings to all probiotics. We have tried to isolate the different safety profiles of diverse probiotic strains. The human intestine is home to more than a trillion live bacteria from about 400 species. The average …

Indomethacin Tocolysis Increases Postnatal Patent Ductus Arteriosus Severity

Postnatally, therapeutic indomethacin administration is usually effective in mediating patent ductus arteriosus (PDA) constriction in premature infants. There are infants, however, who remain resistant to indomethacin and require more aggressive surgical intervention to facilitate ductal closure. Indomethacin tocolysis has been reported to increase the incidence of persistent PDA in premature infants. It was our impression that infants exposed to antenatal indomethacin not only suffered from an increased incidence of PDA, but that they were more symptomatic from PDA and that for them, PDA was more resistant to medical closure. It is this observation that we sought to examine in this study. Methods. Medical records of all mothers and premature neonates with birth weight ≤1500 g, admitted to the neonatal intensive care unit of the Shaare Zedek Medical Center during 1996 and 1997, who survived for at least 1 week, were reviewed retrospectively. Data on maternal indomethacin and steroid exposure, birth weight and gestational age, and ductus status and treatment were analyzed. In our obstetrics department, indomethacin is the medication of choice to inhibit premature labor. Mothers who arrive in premature labor are started on indomethacin therapy, if delivery is not imminent. All infants ≤1500 g were studied by a pediatric cardiologist between 24 and 72 hours of life using two-dimensional echocardiography with color flow mapping to assess ductal patency. Decisions to treat were based on echocardiographic evidence of PDA, along with any of the following clinical signs: bounding pulses, diastolic pressure of ≤25 mm Hg, pulmonary plethora and/or cardiomegaly on chest x-ray, or increasing oxygen requirement with no other explanation. Initial treatment is with indomethacin, if there are no contraindications. Our general approach is to begin therapy with a continuous indomethacin infusion, followed by a course of bolus indomethacin if the infant does not respond. However, each attending neonatologist may treat according to his/her preference (ie, bolus vs continuous). All infants with PDA are followed with serial echocardiographic examinations until the ductus is closed. Results. A total of 105 premature infants met the above criteria. Thirty-six of these 105 infants had echocardiographic signs of a PDA (34.3%). Those with PDA were less mature (gestational age, 28.9 ± 2.6 vs 30.3 ± 2.6 weeks, respectively) and tended to be smaller (1060 ± 270 vs 1166 ± 261 g). Of the 36 infants with PDA, 15 (42%) resolved spontaneously and 21 (58%) were symptomatic and required treatment with indomethacin. There were no differences in gestational age or birth weight between infants whose PDA resolved spontaneously and those requiring indomethacin therapy. Four of the 21 (19%) treated infants remained unresponsive to indomethacin and required ductal ligation. Of 17 infants with PDA who responded to indomethacin therapy, 1 (6%) was treated with a single course of bolus indomethacin, to which he responded, and 16 (94%) were treated with continuous indomethacin and responded promptly. The differences in therapeutic responsiveness to initial treatment with continuous vs bolus indomethacin were not significant. Of the 105 infants, 29 were exposed to indomethacin tocolysis. Those who were exposed to antenatal indomethacin and those who were not were well-matched with respect to birth weight and gestational age. Fifteen (52%) of the 29 exposed infants versus 18 (24%) of the 76 infants not exposed to antenatal indomethacin developed a PDA postnatally (relative risk = 2.1; 95% confidence interval: 1.22–3.74), and 45% of the antenatally exposed infants versus 12% of the nonexposed infants were symptomatic and required indomethacin (relative risk = 1.9; 95% confidence interval: 1.17–3.20). Four of the exposed infants versus none of the unexposed infants required surgical ligation. Among the indomethacin-exposed infants, the nonresponsive and responsive infants were well-matched with regard to birth weight, gestational age, antenatal steroid exposure, and day of life on which indomethacin therapy was initiated. Multiple regression analyses found prenatal indomethacin exposure to be the most significant antecedent variable associated with both the incidence and the severity of PDA, as indicated by the need for indomethacin treatment. Conclusions. We have demonstrated that prenatal indomethacin exposure increases both the incidence and the clinical severity of postnatal PDA, as manifested by increased need for therapeutic indomethacin and surgical ligation. Furthermore, we have shown it to be a more significant risk factor than gestational age, birth weight, or antenatal steroid exposure in both the development and the severity of postnatal PDA. These data should be considered in considerations as to choice of tocolytic therapy.

Contribution of haemolysis to jaundice in Sephardic Jewish glucose-6-phosphate dehydrogenase deficient neonates

We determined the contribution of haemolysis to the development of hyperbilirubinaemia in glucose‐6‐phosphate dehydrogenase (G‐6‐PD) deficient neonates and G‐6‐PD normal controls. Blood carboxyhaemoglobin (COHb), sampled on the third day of life, was measured by gas chromatography, corrected for inhaled carbon monoxide (COHbC), and expressed as a percentage of total haemoglobin concentration (Hb). Serum bilirubin was tested as clinically necessary. 37 non‐jaundiced (peak serum total bilirubin (PSTB) ≤255 μmol/l) and 20 jaundiced (PSTB ≥257 μmol/l) G‐6‐PD‐deficient neonates were compared to 31 non‐jaundiced and 24 jaundiced controls with comparable PSTB values, respectively. COHbC values for the entire G‐6‐PD deficient group were higher than in the controls (0.75 ± 0.17% v 0.62 ± 0.19%, P < 0.001). COHbC and PSTB values did not correlate in the G‐6‐PD‐deficient group (r = 0.15, P > 0.05) but did in the controls (r = 0.58, P < 0.001). COHbC values were increased to a similar extent in the G‐6‐PD‐deficient, non‐jaundiced (0.72 ± 0.16%), the G‐6‐PD‐deficient, jaundiced (0.80 ± 0.19%) and the control, jaundiced (0.75 ± 0.18%) subgroups, compared to the control, non‐jaundiced subgroup (0.53 ± 0.13%) (P < 0.05). Although present in G‐6‐PD deficient neonates, increased haemolysis was not directly related to the PSTB.

Severe Neonatal Hyperbilirubinemia and Kernicterus: Are These Still Problems in the Third Millennium?

Despite efforts to eliminate permanent and irreversible brain damage due to bilirubin encephalopathy and kernicterus, these conditions continue to accompany us into the third millennium. This phenomenon occurs not only in developing countries with emerging medical systems, but in Westernized countries as well. Comprehensive guidelines to detect newborns with jaundice and treat those in whom hyperbilirubinemia has already developed have been formulated in several countries, but have not been successful in completely eliminating the problem. In this appraisal of the situation we review selected aspects of bilirubin encephalopathy and/or kernicterus. We highlight recent reports of severe hyperbilirubinemia and kernicterus, discuss some of the factors responsible for the continuing appearance of these conditions, and briefly review what can be done to decrease bilirubin-related morbidity and mortality to the minimum.

Protective effect of bilirubin in ischemia-reperfusion injury in the rat intestine.

Background Although bilirubin, which crosses the blood–brain barrier, can cause irreversible brain damage, it also possesses antioxidant properties that may be protective against oxidative stress. Intestinal ischemia–reperfusion (IR) injury results in cell destruction, mediated via the generation of reactive oxygen species. Although increased serum bilirubin is correlated with increased antioxidant potential in the face of hyperoxia, evidence of bilirubin-associated protective effect against IR injury remains nonspecific. We therefore sought to investigate whether hyperbilirubinemia would be protective against IR injury to the intestine. Methods Young adult rats were randomly assigned to one of three groups: 1) IR/control (n = 12); 2) IR/hyperbilirubinemia (n = 10), in which IR was generated while the rats were treated with a continuous infusion of bilirubin; and 3) hyperbilirubinemia controls (n = 10). Blood and intestinal tissue samples were obtained to determine serial thiobarbituric acid reducing substances (index of lipid peroxidation) and for xanthine oxidase/xanthine dehydrogenase and glutathione/glutathione disulfide ratios. Intestinal histopathology was graded from 1 (normal) to 4 (severe necrotic lesions). Results Histopathologic scoring and circulating and tissue thiobarbituric acid reducing substances were highest in the IR/control animals compared with either the IR/hyperbilirubinemics or the controls. All of these are consistent with the most severe injury in this group. Xanthine oxidase/xanthine dehydrogenase ratios were not significantly different among the groups. Conclusion Hyperbilirubinemia ameliorates the extent of intestinal IR injury in our model and appears to act as an antioxidant. This study supports the concept that bilirubin possesses some beneficial properties in vivo, although no direct clinical conclusions can be drawn from these data.

Glucose-6-phosphate dehydrogenase deficiency and severe neonatal hyperbilirubinemia: a complexity of interactions between genes and environment.

Glucose-6-phosphate dehydrogenase deficiency is a commonly occurring genetic condition, likely to be encountered today in virtually any corner of the globe. Sudden episodes of hemolysis associated with the condition may result in exponential increases in serum total bilirubin concentrations to levels at which bilirubin-induced neurologic damage may occur. The hyperbilirubinemia is the result of complex interactions between genes and environment. Neonatal screening programs coupled with parental and medical caretaker education may be successful in limiting the severity of disease.