Nutrients and Microbiota in Lung Diseases of Prematurity: The Placenta-Gut-Lung Triangle.

Cardiorespiratory function is not only the foremost determinant of life after premature birth, but also a major factor of long-term outcomes. However, the path from placental disconnection to nutritional autonomy is enduring and challenging for the preterm infant and, at each step, will have profound influences on respiratory physiology and disease. Fluid and energy intake, specific nutrients such as amino-acids, lipids and vitamins, and their ways of administration -parenteral or enteral-have direct implications on lung tissue composition and cellular functions, thus affect lung development and homeostasis and contributing to acute and chronic respiratory disorders. In addition, metabolomic signatures have recently emerged as biomarkers of bronchopulmonary dysplasia and other neonatal diseases, suggesting a profound implication of specific metabolites such as amino-acids, acylcarnitine and fatty acids in lung injury and repair, inflammation and immune modulation. Recent advances have highlighted the profound influence of the microbiome on many short- and long-term outcomes in the preterm infant. Lung and intestinal microbiomes are deeply intricated, and nutrition plays a prominent role in their establishment and regulation. There is an emerging evidence that human milk prevents bronchopulmonary dysplasia in premature infants, potentially through microbiome composition and/or inflammation modulation. Restoring antibiotic therapy-mediated microbiome disruption is another potentially beneficial action of human milk, which can be in part emulated by pre- and probiotics and supplements. This review will explore the many facets of the gut-lung axis and its pathophysiology in acute and chronic respiratory disorders of the prematurely born infant, and explore established and innovative nutritional approaches for prevention and treatment.

Dysbiosis and Prematurity: Is There a Role for Probiotics?

Healthy microbiota is a critical mediator in maintaining health and it is supposed that dysbiosis could have a role in the pathogenesis of a number of diseases. Evidence supports the hypothesis that maternal dysbiosis could act as a trigger for preterm birth; aberrant colonization of preterm infant gut might have a role in feeding intolerance and pathogenesis of necrotizing enterocolitis. Despite several clinical trials and meta-analyses, it is still not clear if modulation of maternal and neonatal microbiota with probiotic supplementation decreases the risk of preterm birth and its complications.

Filling the Gaps: Current Research Directions for a Rational Use of Probiotics in Preterm Infants.

The use of probiotics among very low-birth-weight infants is constantly increasing, as probiotics are believed to reduce the incidence of severe diseases such as necrotizing enterocolitis and late-onset sepsis and to improve feeding tolerance. However, despite the enthusiasm towards these products in neonatal medicine, theoretical knowledge and clinical applications still need to be improved. The purpose of this review is to give an overview of the most important gaps in the current literature about potential uses of probiotics in preterm infants, highlighting promising directions for future research. Specifically, further well-designed studies should aim at clarifying the impact of the type of feeding (mother's milk, donor milk, and formula) on the relationship between probiotic supplementation and clinical outcome. Moreover, future research is needed to provide solid evidence about the potential greater efficacy of multi-strain probiotics compared to single-strain products. Safety issues should also be addressed properly, by exploring the potential of paraprobiotics and risks connected to antibiotic resistance in preterm infants. Last, in light of increasing commercial and public interests, the long-term effect of routine consumption of probiotics in such a vulnerable population should be also evaluated.

Necrotizing enterocolitis - classification and two initial steps towards prevention.

The premature infant suffers from immaturity of all organ systems, one of them being the gastrointestinal tract. When the infant is born, the immature gastrointestinal tract is exposed to milk and simultaneously colonized by high densities of bacteria. The combination of milk, microbiota and an immature gut, leaves the infant vulnerable to developing the dreaded intestinal emergency necrotizing enterocolitis (NEC). NEC is often very aggressive and no cure exists, which means that prevention is an utmost important topic to researchers, physicians, parents - and infants.   Despite immense research during the last decades, no specific test to determine if an infant suffers from NEC exists. Most neonatal units use Bell's staging criteria, which are based on clinical and radiographic findings, as a diagnostic tool; however the diagnosis given according to Bell's stages has not been validated. In study I, we aimed to determine the validity of the NEC diagnosis given at discharge. An expert panel consisting of a neonatologist, a paediatric surgeon and a paediatric radiologist served as the golden standard. We found that the diagnosis given at discharge had a poor validity which significantly affected the reported incidence of NEC in the neonatal department at Rigshospitalet, Denmark. The validity of the NEC diagnosis was worse than the validity of most other paediatric diagnoses that had been investigated.   In studies II and III, we aimed to explore possible means of NEC prevention. The role of nutrition in NEC development is well established with mother's milk as the best option to avoid NEC in the preterm infant. Maternal milk is, however, most often not available in sufficient amounts during the first days of life, and preterm infant formula or human donor milk is used in its absence. Studies in preterm piglets showed that bovine colostrum equally to human donor milk protected against NEC compared to infant formula. Furthermore, bovine colostrum was superior to human donor milk in stimulating gut immunity and digestive functions.   Hence, in study II we aimed to design a pilot study of bovine colostrum used as a supplement to maternal milk in the first days of life and to determine if the study was feasible. In the paper, we present the protocol and the results of the first two phases of the Precolos study in which 12 infants were included and received pasteurized, spray-dried and reconstituted bovine colostrum during the first days of life as the first infants in the world. We found that the infants tolerated bovine colostrum without clinical adverse effects, but we also observed a transient hypertyrosinemia on day seven of life in five infants. The results were evaluated by a safety management board which encouraged us to continue the pilot study with the last phase, which was a randomized controlled trial of 20+20 infants comparing supplementation with bovine colostrum to supplementation with standard nutrition. The randomized trial has just finished recruitment.   At last, we wanted to shed light on a possible microbiological angle of NEC prevention. Dysbiosis and bacterial translocation are believed to play a crucial role in the development of NEC as intestinal pneumatosis, which occurs when bacteria produce gas inside the intestinal wall, is a pathognomonic radiographic finding. In a quality improvement study from the US published in 2014, NEC incidence was significantly reduced after the implementation of several quality improvement interventions. Standardized weekly exchange of nasogastric feeding tubes was suggested as one of the potential NEC-reducing interventions.   In the neonatal unit at Rigshospitalet, Denmark, preterm infants are fed 8-12 times daily through a resident nasogastric feeding tube which is exposed to body temperature, contains milk residuals from the last meal and is handled by both parents and personnel. Since bacterial pollution of milk given through the nasogastric feeding tube might be NEC-inducing, we aimed in study III to determine the bacterial load given to the infants when feeding them through a tube. We collected 92 used nasogastric feeding tubes and flushed them with one ml saline each to imitate a meal given through them. Eighty-nine percent of the tubes contaminated the meals with more than 1000 colony-forming units of bacteria and fifty-five percent contaminated the meals with the possible pathogens Enterobacteriaceae or Staphylococcus aureus. The concentration of bacteria in the saline flushed through the tubes was as high as 109 colony-forming units per ml; however, neither the risk of contamination nor the concentration of bacteria in the flush was associated with the duration of use. Implementation of standardized weekly exchange of feeding tubes would therefore not prevent the contamination of meals.   In conclusion, the studies included in this thesis serve as a base for future studies investigating the prevention of NEC. We found a poor validity of the NEC diagnosis given at discharge. This should be kept in mind when conducting epidemiological studies of NEC and especially when conducting interventional trials with NEC as an outcome. If the findings of the randomized part of the Precolos study indicate a positive effect of bovine colostrum and do not give rise to concerns regarding feasibility, safety or tolerability, a large-scale randomized controlled study with NEC as the primary outcome will be planned. Based on the high concentrations of bacteria found in the nasogastric feeding tubes, a randomized controlled trial investigating whether the frequency of feeding tube exchange affects the early colonization has been commenced in the neonatal department at Rigshospitalet. Hopefully, the results of these studies will bring us closer to preventing NEC in the future.

Gut microbiota and the pathogenesis of necrotizing enterocolitis in preterm neonates.

Necrotizing enterocolitis (NEC) remains a devastating intestinal disease in preterm neonates. In this population, disruption of the gut microbiota development, mainly due to organ immaturity, antibiotic use and hospital microbial environment, plays a key role in the pathogenesis of NEC. This gut dysbiosis has been associated with opportunistic pathogens overgrowth, expression of virulence factors, altered metabolic functions and inflammatory dysregulated responses. In this review, we provide an updated summary of the host and gut microbiota interactions during the formative early life. We also explore the key determinants of gut dysbiosis in preterm neonates with NEC. Finally, we discuss the promising role of bacteriotherapy in the management of NEC, the aim being to shape or restore the beneficial gut bacterial communities.

Probiotic supplementation for preventing invasive fungal infections in preterm neonates--a systematic review and meta-analysis.

Invasive fungal infections (IFI) are associated with significant health burden in preterm neonates. The objective of this study was to systematically review effect of probiotic supplementation (PS) for preventing IFI in preterm neonates. We searched Cochrane Central Register of Controlled Trials, Medline, Embase, Cumulative Index of Nursing and Allied Health Literature, and proceedings of the Pediatric Academic Society meetings in August 2014. Study selection was performed on randomised controlled trials (RCT) of PS in neonates born <37 weeks. Primary outcome of this study was IFI (Isolation of fungus in blood/body fluids) and secondary outcome was fungal gut colonisation. Information on IFI/colonisation was available in 8 of 27 RCT. Meta-analysis (fixed effects model) showed that PS reduced the risk of IFI (RR: 0.50, 95% CI: 0.34, 0.73, I(2) = 39%). Results were not significant with random effects model (RR: 0.64, 95%, CI: 0.30, 1.38, P = 0.25, I(2) = 39%). Analysis after excluding the study with a high baseline incidence (75%) of IFI showed that PS had no significant benefits (RR: 0.89; 95% CI: 0.44, 1.78). Of the five studies reporting on fungal gut colonisation, three reported benefits of probiotics; two did not. Current evidence is limited to derive firm conclusions on the effect of PS for preventing IFI/gut colonisation in preterm neonates.

Inadequate vancomycin therapy in term and preterm neonates: a retrospective analysis of trough serum concentrations in relation to minimal inhibitory concentrations.

BACKGROUND: Vancomycin is effective against gram-positive bacteria and the first-line antibiotic for treatment of proven coagulase-negative staphylococcal infections. The aim of this study is bipartite: first, to assess the percentage of therapeutic initial trough serum concentrations and second, to evaluate the adequacy of the therapeutic range in interrelationship with the observed MIC-values in neonates. METHODS: In this study, preterm and term neonates admitted at a tertiary NICU in the Netherlands from January 2009 to December 2012 and treated with vancomycin for a proven gram-positive infection were included. Trough serum concentrations were measured prior to administration of the 5th dose. Trough concentrations in the range of 10 to 15 mg/L were considered therapeutic. Staphylococcal species minimal inhibitory concentrations (MIC's) were determined using the E-test method. Species identification was performed by matrix-assisted laser desorption/ionisation mass spectrometry. RESULTS: Of the 112 neonates, 53 neonates (47%) had sub-therapeutic initial trough serum concentrations of vancomycin, whereas 22% had supra-therapeutic initial trough serum concentrations. In all patients doses were adjusted on basis of the initial trough concentration. In 40% (23/57) of the neonates the second trough concentration remained sub-therapeutic. MIC's were determined for 30 coagulase-negative Staphylococcus isolates obtained from 19 patients. Only 4 out of 19 subjects had a trough concentration greater than tenfold the MIC. CONCLUSIONS: Forty-seven percent of the neonates had sub-therapeutic initial trough serum concentrations of vancomycin. The MIC-data indicate that the percentages of underdosed patients may be greater. It may be advisable to increase the lower limit of the therapeutic range for European neonates.

Successful treatment of an infant infected with refractory C. parapsilosis with caspofungin.

Neonatal Candida infections are the leading cause of invasive fungal infections that might cause severe morbidity or mortality in a large majority of those affected. Although Candida albicans has been the most common species, Candida parapsilosis is increasingly being recognized as an important cause of invasive candidiasis in neonates. Among the Candida species, C. parapsilosis has been commonly isolated and shown to be less susceptible in vitro to echinocandins than other Candida species. We report an infant who had refractory C. parapsilosis septicemia cured with caspofungin.

Rhodotorula fungemia: two cases and a brief review.

Rhodotorula is emerging as an important cause of nosocomial and opportunistic infections. We present two cases of Rhodotorula mucilaginosa fungemia diagnosed over a period of 3 months at our hospital. The first case was of a pre-term neonate in the neonatal ICU who presented with respiratory failure and sepsis. The second involved an adult female who had been injured in a road traffic accident requiring an operation for a hematoma and was later shifted to the medical ICU. For a new hospital like ours, finding two cases of Rhodotorula fungemia within a span of 3 months prompted us to describe them in this report. These cases emphasize the emerging importance of Rhodotorula mucilaginosa as a pathogen and the importance of identification and MIC testing for all fungal isolates recovered from the blood stream.

Effect of Bifidobacterium animalis subsp lactis supplementation in preterm infants: a systematic review of randomized controlled trials.

OBJECTIVE: To systematically evaluate and update evidence on the efficacy and safety of Bifidobacterium animalis subsp lactis CNCM I-3446 supplementation in preterm infants. MATERIALS AND METHODS: The Cochrane Library and MEDLINE databases and major pediatric conference proceedings were searched in December 2008 for randomized controlled trials (RCTs). The company that manufactures B lactis was contacted for unpublished data. The review was restricted to RCTs performed in preterm infants <37 weeks of gestation and/or with a birth weight <2500 g. RESULTS: Four RCTs involving 324 infants met the inclusion criteria. Compared with controls, B lactis supplementation has the potential to increase fecal bifidobacteria counts and to reduce Enterobacteriaceae and Clostridium spp counts. It also can reduce stool pH and fecal calprotectin concentrations, increase fecal immunoglobulin A and short-chain fatty acid concentrations, and decrease intestinal permeability. Compared with controls, B lactis supplementation had no effect on the risk of necrotizing enterocolitis stage > or = 2 (3 RCTs, n = 293, risk ratio [RR] 0.53, 95% CI 0.16-1.83), risk of sepsis (2 RCTs, 397 cultures, RR 0.6, 95% CI 0.07-5.2), and use of antibiotics (2 RCTs, n = 255, RR 0.67, 95% CI 0.28-1.62). The power of these studies, however, does not allow for a definitive statement regarding a reduced risk of necrotizing enterocolitis. B lactis supplementation did have some effects on anthropometric parameters. No adverse events associated with B lactis supplementation were reported. CONCLUSIONS: Evidence regarding the potential beneficial effects of B lactis supplementation in preterm infants is encouraging. Further studies to assess clinically relevant outcomes are needed.

Neutral and acidic oligosaccharides in preterm infants: a randomized, double-blind, placebo-controlled trial.

BACKGROUND: Serious infectious morbidity is high in preterm infants. Enteral supplementation of prebiotics may reduce the incidence of serious infections, especially infections related to the gastrointestinal tract. OBJECTIVE: The objective was to determine the effect of enteral supplementation of a prebiotic mixture consisting of neutral oligosaccharides ((SC)GOS/(LC)FOS) and acidic oligosaccharides (AOS) on serious infectious morbidity in preterm infants. DESIGN: In a randomized controlled trial, preterm infants (gestational age <32 wk and/or birth weight <1500 g) received enteral supplementation of 80% (SC)GOS/(LC)FOS and 20% AOS (1.5 g . kg(-1) . d(-1)) or placebo (maltodextrin) between days 3 and 30 of life. Serious infectious morbidity was defined as a culture positive for sepsis, meningitis, pyelonephritis, or pneumonia. The analysis was performed by intention-to-treat and per-protocol, defined as > or =50% supplementation dose during the study period. RESULTS: In total, 113 preterm infants were included. Baseline and nutritional characteristics were not different between groups. In the intention-to-treat analysis, the incidence of > or =1 serious infection, > or =1 serious endogenous infection, or > or =2 serious infectious episodes was not significantly different in the (SC)GOS/(LC)FOS/AOS-supplemented and placebo groups. In the per-protocol analysis, there was a trend toward a lower incidence of > or =1 serious endogenous infection and > or =2 serious infectious episodes in the (SC)GOS/(LC)FOS/AOS-supplemented group than in the placebo group (P = 0.09 and P = 0.07, respectively). CONCLUSIONS: Enteral supplementation of (SC)GOS/(LC)FOS/AOS does not significantly reduce the risk of serious infectious morbidity in preterm infants. However, there was a trend toward a lower incidence of serious infectious morbidity, especially for infections with endogenous bacteria. This finding suggests a possible beneficial effect that should be evaluated in a larger study. This trial was registered at isrctn.org as ISRCTN16211826.

Routine use of fluconazole prophylaxis in a neonatal intensive care unit does not select natively fluconazole-resistant Candida subspecies.

BACKGROUND: We have previously demonstrated efficacy against fungal colonization and infection of fluconazole prophylaxis that was routinely administered since 2001 in our ICU for preterm infants <1500 g at birth (VLBW). With prolonged use, concerns exist for the emergence of acquired fungal resistance and of Candida subspecies that are natively fluconazole-resistant (NFR), mostly Candida glabrata and Candida krusei. METHODS: We evaluated retrospectively all clinical and surveillance fungal isolates obtained from VLBW infants in our NICU during a 10-year period (1997-2006). Each fungal isolate was speciated, infants colonized or infected with NFR-Candida spp were identified and the incidence rates of colonization and infection by these fungal species were calculated. A comparison was made of the 6-year (2001-2006) prophylaxis period with the 4-year (1997-2000) preprophylaxis period. RESULTS: Overall, colonization by NFR-Candida spp ranged between 2.8% and 6.6% of VLBW infants yearly admitted, without any increasing trend during the study period. There were 18 of 434 (4.1%) neonates colonized by these species. Five episodes of systemic fungal infections caused by NFR-Candida spp occurred (incidence rate, 1.1%). No significant differences were detected when compared with the preprophylaxis period, when 11 of 295 infants (3.7%) were colonized by NFR-Candida spp and 4 episodes of infection occurred (1.4%) (P = 0.84 and 0.76, respectively). CONCLUSIONS: Fluconazole prophylaxis administered to VLBW neonates in 4- to 6-week courses after birth does not lead to the emergence of natively fluconazole-resistant Candida spp.

Effect of topical emollient treatment of preterm neonates in Bangladesh on invasion of pathogens into the bloodstream.

Topical emollient therapy may reduce the incidence of serious infections and mortality of preterm infants in developing countries. We tested whether emollient therapy reduced the burden of pathogens on skin and/or prevented bacterial translocation. Neonates <33 wk gestational age were randomized to treatment with sunflower seed oil (SSO) or Aquaphor or the untreated control group. Skin condition score and skin cultures were obtained at enrollment and on d 3, 7, and weekly thereafter, and blood cultures were obtained for episodes of suspected nosocomial sepsis. For analysis, blood cultures were paired with skin cultures obtained 0-3 d before the blood culture. Skin condition scores at 3 d were better in patients treated with either emollient compared with untreated controls; however, skin flora was similar across the groups. The SSO group showed a 72% elevated odds of having a false-positive (FP) skin culture associated with a negative blood culture (i.e. skin flora blocked from entry into blood) compared with the control group. Topical therapy with SSO reduced the passage of pathogens from the skin surface into the bloodstream of preterm infants.

A study of pre-antibiotic bacteriology in 125 patients with necrotizing enterocolitis.

Over a five-year period, 125 newborns with necrotizing enterocolitis (NEC) were managed by us. Their mean birthweight was 1700 g and mean maturity was 32 weeks. Before commencement of antibiotics, routine septic work-up was done in order to define the bacterial spectrum and antibiotic sensitivity. The study includes aerobic and anaerobic cultures of gastric and pharyngeal aspirates, blood cultures, umbilical swabs and culture of umbilical catheter tips in relevant cases. Peritoneal swab results were also analyzed if laparatomy was performed. Positive cultures were present in 45 patients (36%) with 55 positive specimens. Fifteen types of organism were isolated: the commonest was Enterobacter (29%), followed by E. coli (14.5%) and Klebsiella (13%). They were resistant to ampicillin and first-generation cephalosporin. These organisms were usually opportunistic pathogens. Overgrowth of them may be the cause of NEC. Regular review of the antibiotic sensitivity of these organisms allows prompt and appropriate choice of antibiotics. At the same time, antibiotic sensitivity for these organisms was analyzed to guide us in the choice of antibiotic therapy.

[Septic arthritis and osteomyelitis as a complication of neonatal intensive care (author's transl)]. / Septische Arthritis und Osteomyelitis als Komplikation neonataler Intensivpflege.

In a prematurely born infant of a diabetic mother a purulent arthritis with osteomyelitis of the elbow occurred 18 days after an enterobacter aerogenes-septicemia was proved. Enterobacter (aerobacter) aerogenes is a nosocomial gramnegative germ, that is more and more regarded responsible for infection of the newborn in intensive care units. In accordance with the literature recording a high rate functional loss after septic arthritis also our patient suffered from a mobility deficiency in his right elbow a year after the onset of the disease.