Importance of the environment and the faecal flora of infants, nursing staff and parents as sources of gram-negative bacteria colonizing newborns in three neonatal wards

Association Between the Mode of Delivery and Infant Gut Microbiota Composition Up to 6 Months of Age: A Systematic Literature Review Considering the Role of Breastfeeding

CONTEXT

Cesarean section (CS), breastfeeding, and geographic location can influence the infant microbiota.

OBJECTIVE

In this systematic review, evidence of the association between mode of delivery and infant gut microbiota up to 6 months of age was evaluated, as was the role of breastfeeding in this association, according to PRISMA guidelines.

DATA SOURCE

The Pubmed, Web of Science, Scopus, Embase, Medical Database, and Open Grey databases were searched.

DATA EXTRACTION

A total of 31 observational studies with ≥2 infant stool collections up to the sixth month of age and a comparison of gut microbiota between CS and vaginal delivery (VD) were included.

DATA ANALYSIS

Infants born by CS had a lower abundance of Bifidobacterium and Bacteroides spp. at almost all points up to age 6 months. Populations of Lactobacillus, Bifidobacterium longum, Bifidobacterium catenulatum, and Escherichia coli were reduced in infants delivered by CS. Infants born by CS and exclusively breastfed had greater similarity with the microbiota of infants born by VD.

CONCLUSIONS

Species of Bifidobacterium and Bacteroides are potentially reduced in infants born by CS. Geographic location influenced bacterial colonization.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. 42017071285.

Candida species as commensal gut colonizers: A study of 133 longitudinally followed Swedish infants

The gut microbiota harbor a wide range of bacterial species, but also yeasts may be part of this ecosystem. Infants who are being treated in intensive care units are often colonized by Candida species. However, little is known regarding commensal yeast colonization of healthy infants and young children. Here the acquisition of yeast species was studied in a birth-cohort including 133 healthy Swedish infants. A rectal swab sample was obtained on day 3 of life, and fresh fecal samples were obtained at regular intervals up to 3 years of age; the samples were cultured quantitatively for yeasts. Colonization with yeasts increased rapidly in the first months of life, with 73/133 infants (55%) colonized at 6 months of age. The yeast numbers in positive samples decreased from an average of 105 cfu/g in infants aged 0-2 months to 103.5 cfu/g at 3 years of age. Candida albicans was the most frequently isolated species and reached higher population counts than the other species in culture-positive infants. The yeast colonization rate did not differ between infants who were delivered vaginally and those birthed via Caesarean section, whereas breastfed infants showed a lower colonization rate (p < 0.05 for 1 year of age compared to the other infants). The results demonstrate that yeasts, particularly C. albicans and C. parapsilosis (sensu lato), are common commensals in the gut microbiota of healthy infants and young children.

Delayed Establishment of Gut Microbiota in Infants Delivered by Cesarean Section

The maternal vaginal microbiome is an important source for infant gut microbiome development. However, infants delivered by Cesarean section (CS) do not contact the maternal vaginal microbiome and this delivery method may perturb the early establishment and development of the gut microbiome. The aim of this study was to investigate the early gut microbiota of Korean newborns receiving the same postpartum care services for two weeks after birth by delivery mode using fecal samples collected at days 3, 7, and 14. Early gut microbiota development patterns were examined using 16S rRNA gene-based sequencing from 132 infants either born vaginally (VD, n = 64) or via Cesarean section (CS, n = 68). VD-born neonates showed increased alpha diversity in infant fecal samples collated at days 7 and 14 compared to those from day 3, while those of CS infants did not differ (p < 0.015). Bacterial structures of infants from both groups separated at day 7 (p < 0.001) and day 14 (p < 0.01). The bacterial structure of VD infants gradually changed over time (day 3 vs. day 7, p < 0.012; day 3 vs. day 14, p < 0.001). Day 14 samples of CS infants differed from day 3 and 7 samples (day 3 vs. day 14, p < 0.001). VD infant relative abundance of Bifidobacterium (days 7, 14), Bacteroides (days 7, 14), and Lachnospiraceae (day 7) significantly increased compared to CS infants, with a lower abundance of Enterobacteriaceae (found in all periods of the CS group) (LDA > 3.0). Relative abundances of Bifidobacterium, Lactobacillus, and Staphylococcus were significantly increased in both VD and CS groups at day 14 (LDA > 3.0). Predicted functional analysis showed that VD infants had overrepresented starch/sucrose, amino acid and nucleotide metabolism in gut microbiota with depleted lipopolysaccharide biosynthesis until day 14 compared to CS infants. This study confirmed that delivery mode is the major determinant of neonatal intestinal microbiome establishment and provides a profile of microbiota perturbations in CS infants. Our findings provide preliminary insight for establishing recovery methods to supply the specific microbes missing in CS infants.

Reduction of hospital-acquired infections in the neonatal intensive care unit: A long-term commitment

We instituted quality improvement program. We compare the infection rate before (2011-2012) and after (2013-2015). Central line associated blood stream infection episodes decreased from 15.2 to 2.29 episodes per 1000 catheter days (P = .004). We found two major changes, 1. Hand hygiene increased mainly "before aseptic task", from 69.9% to 89.9% and 2. A significant decrease in the length of the catheter use from 5.4 ± 4.5 before to 4.4 ± 2.5 days after the intervention (P = .001).

Factors Influencing the Intestinal Microbiome During the First Year of Life

The intestinal microbiome plays a crucial role in the development of the immune system and regulation of immune responses. Many factors influence the composition of the infant intestinal microbiome and therefore the development and function of the immune system. This, in turn, may alter the risk of subsequent allergies, autoimmune diseases and other adverse health outcomes. Here, we review factors that influence the composition of the intestinal microbiome during the first year of life, including birth location, gestational age, delivery mode, feeding method, hospitalization, antibiotic or probiotic intake and living conditions. Understanding how the early intestinal microbiome is established and how this is perturbed provides many opportunities for interventions to improve health.

Bifidobacterial strains in the intestines of newborns originate from their mothers

The gastrointestinal tract is believed to be colonized rapidly with bacteria immediately from birth. The source of these intestinal microbes is an ongoing topic of interest because increasing evidence suggests that the composition of the initial intestinal bacterial colonization strongly affects health. In particular, the source of bifidobacteria has received marked attention because these bacteria are suggested to play a crucial role in protecting against susceptibility to diverse diseases later in life. However, the source of these microbes has remained unclear. Recently, it was confirmed that mothers transmit their unique bifidobacterial strains to their children shortly after birth. The transmitted strains predominate during early infancy, suggesting that maternal intestinal bifidobacteria are an important source of the infant gut microbiota. Accordingly, maintenance of a healthy, balanced gut microbiota during pregnancy has an important positive influence on the newborn gut microbiota.

Comparison of Commensal Escherichia coli Isolates from Adults and Young Children in Lubuskie Province, Poland: Virulence Potential, Phylogeny and Antimicrobial Resistance

Commensal Escherichia coli population is a dynamic structure which may be important in the pathogenesis of extraintestinal infections. The aim of this study was the comparison of genetic diversity of commensal E. coli isolates from two age group—adults and young children. E. coli strains were isolated on MacConkey agar and identified by biochemical tests. Determination of four major phylogenetic groups, identification of virulence genes and antimicrobial resistance determinants were performed by using multiplex or simplex PCR. Phenotypic analysis of resistance was based on disc-diffusion method. The prevalence of virulence genes was significantly higher among isolates from adults than from young children. Phylogroup B2 predominated among E. coli from adults, whereas phylogroup A was the most common in isolates from young children. The analyses of antimicrobial resistance revealed that resistance to at least one antimicrobial agent and multidrug-resistance were detected significantly more frequent in the isolates from adults than from young children. This study documented that the commensal E. coli isolates from adults showed greater genetic diversity than from young children and constitutes a substantial reservoir of the virulence genes typical for extraintestinal pathogenic E. coli.

Cesarean section changes neonatal gut colonization

BACKGROUND

Delivery by means of cesarean section has been associated with increased risk of childhood immune-mediated diseases, suggesting a role of early bacterial colonization patterns for immune maturation.

OBJECTIVE

We sought to describe the influence of delivery method on gut and airway colonization patterns in the first year of life in the Copenhagen Prospective Studies on Asthma in Childhood2010 (COPSAC2010) birth cohort.

METHODS

Seven hundred children from the COPSAC2010 birth cohort participated in this analysis. Fecal samples were collected at age 1 week, 1 month, and 1 year, and hypopharyngeal aspirates were collected at age 1 week, 1 month, and 3 months and cultured for bacteria. Detailed information on delivery method, intrapartum antibiotics, and lifestyle factors was obtained by personal interviews.

RESULTS

Seventy-eight percent of the children were born by means of natural delivery, 12% by means of emergency cesarean section, and 9% by means of elective cesarean section. Birth by means of cesarean section was significantly associated with colonization of the intestinal tract by Citrobacter freundii, Clostridium species, Enterobacter cloacae, Enterococcus faecalis, Klebsiella oxytoca, Klebsiella pneumoniae, and Staphylococcus aureus at age 1 week, whereas colonization by Escherichia coli was associated with natural birth. At age 1 month, these differences were less prominent, and at age 1 year, they were not apparent, which was confirmed by means of multivariate data-driven partial least squares analyses. The initial airway microbiota was unaffected by birth method.

CONCLUSION

Delivery by means of cesarean section was associated with early colonization patterns of the neonatal gut but not of the airways. The differences normalized within the first year of life. We speculate that microbial derangements, as indicated in our study, can demonstrate a possible link between delivery by means of cesarean section and immune-mediated disease.

Metagenomic Sequencing with Strain-Level Resolution Implicates Uropathogenic E. coli in Necrotizing Enterocolitis and Mortality in Preterm Infants

Necrotizing enterocolitis (NEC) afflicts approximately 10% of extremely preterm infants with high fatality. Inappropriate bacterial colonization with Enterobacteriaceae is implicated, but no specific pathogen has been identified. We identify uropathogenic E. coli (UPEC) colonization as a significant risk factor for the development of NEC and subsequent mortality. We describe a large-scale deep shotgun metagenomic sequence analysis of the early intestinal microbiome of 144 preterm and 22 term infants. Using a pan-genomic approach to functionally subtype the E. coli, we identify genes associated with NEC and mortality that indicate colonization by UPEC. Metagenomic multilocus sequence typing analysis further defined NEC-associated strains as sequence types often associated with urinary tract infections, including ST69, ST73, ST95, ST127, ST131, and ST144. Although other factors associated with prematurity may also contribute, this report suggests a link between UPEC and NEC and indicates that further attention to these sequence types as potential causal agents is needed.

Bacterial community structure associated with elective cesarean section versus vaginal delivery in Chinese newborns

OBJECTIVES

Increasing attention is being paid to the potential for cesarean birth to influence the taxa of the bacteria that compose the infant intestinal microbiota. The present study characterized the diversity of the intestinal microbiota in newborn infants delivered vaginally (VD) or by cesarean section (CD).

METHODS

A cross-sectional study was performed using fecal specimens collected on days 2 and 4 of postnatal life from 25 VD infants and 16 CD infants. Profiles of the fecal microbiota were analyzed using polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis in combination with 16S ribosomal RNA (rRNA) gene sequencing of the clones corresponding to the degenerating gradient gel electrophoresis (DGGE) bands.

RESULTS

On days 2 and 4 of postnatal life, VD and CD infants did not differ in the richness and evenness of the fecal bacterial community; however, the taxa of the fecal microbiota were significantly different between the 2 groups. In VD infants, Escherichia coli, Bacteroides sp, and Bifidobacterium longum were the dominant microbes. In CD infants, Staphylococcus sp, Clostridium sp, Enterobacter sp, and Streptococcus sp were more common.

CONCLUSIONS

These results demonstrate that delivery method has a profound influence on the structure of the intestinal microbiota in Chinese newborn infants. This is in accordance with data reported in other regions.

Microbiota of the chicken gastrointestinal tract: influence on health, productivity and disease

Recent advances in the technology available for culture-independent methods for identification and enumeration of environmental bacteria have invigorated interest in the study of the role of chicken intestinal microbiota in health and productivity. Chickens harbour unique and diverse bacterial communities that include human and animal pathogens. Increasing public concern about the use of antibiotics in the poultry industry has influenced the ways in which poultry producers are working towards improving birds' intestinal health. Effective means of antibiotic-independent pathogen control through competitive exclusion and promotion of good protective microbiota are being actively investigated. With the realisation that just about any change in environment influences the highly responsive microbial communities and with the abandonment of the notion that we can isolate and investigate a single species of interest outside of the community, came a flood of studies that have attempted to profile the intestinal microbiota of chickens under numerous conditions. This review aims to address the main issues in investigating chicken microbiota and to summarise the data acquired to date.

Reduction of central line-associated bloodstream infection rates in a neonatal intensive care unit after implementation of a multidisciplinary evidence-based quality improvement collaborative: A four-year surveillance

BACKGROUND

The use of central venous catheters has permitted lifesaving treatment for critically ill neonates; however, the attributable mortality rate for central line-associated bloodstream infections (CLABSIs) has been estimated to be between 4% and 20%. In 2006/2007, the authors' neonatal intensive care unit (NICU) had a CLABSI rate that was nearly twofold higher than that reported by other Canadian NICUs.

OBJECTIVE

To implement a quality improvement collaborative to reduce the incidence of neonatal CLABSI.

METHODS

A retrospective observational study was performed to compare CLABSI in neonates admitted to the authors' level III NICU between August 2007 and March 2011. The entire study period was divided into four time periods to evaluate secular trends. A comprehensive catheter-related bloodstream infection prevention initiative was implemented in August 2007. The initiatives included staff education, standardization of skin preparation protocol, introduction of new antiseptic agents, implementation of central catheter insertion and maintenance checklists, reinforcement of the use of maximal sterile barrier precautions, and revision of the central catheter configuration and maintenance protocols.

RESULTS

The median CLABSI rate of 7.9 per 1000 catheter days at the beginning of the study (period 1 [August 2007 to June 2008]) gradually decreased over the entire study period (P=0.034): period 2 (July 2008 to May 2009), 3.3 per 1000 catheter days; period 3 (June 2009 to April 2010), 2.6 per 1000 catheter days; and period 4 (May 2010 to March 2011), 2.2 per 1000 catheter days.

CONCLUSION

A multidisciplinary evidence-based quality improvement collaborative resulted in a significant reduction in the CLABSI rate. Continuous quality improvement measures are required to reduce catheter-related bloodstream infections among low-birth-weight infants.

Mother-to-infant transmission of intestinal bifidobacterial strains has an impact on the early development of vaginally delivered infant's microbiota

Objectives

Bifidobacterium species are one of the major components of the infant's intestine microbiota. Colonization with bifidobacteria in early infancy is suggested to be important for health in later life. However, information remains limited regarding the source of these microbes. Here, we investigated whether specific strains of bifidobacteria in the maternal intestinal flora are transmitted to their infant's intestine.

Materials and Methods

Fecal samples were collected from healthy 17 mother and infant pairs (Vaginal delivery: 12; Cesarean section delivery: 5). Mother's feces were collected twice before delivery. Infant's feces were collected at 0 (meconium), 3, 7, 30, 90 days after birth. Bifidobacteria isolated from feces were genotyped by multilocus sequencing typing, and the transitions of bifidobacteria counts in infant's feces were analyzed by quantitative real-time PCR.

Results

Stains belonging to Bifidobacterium adolescentis, Bifidobacterium bifidum, Bifidobacterium catenulatum, Bifidobacterium longum subsp. longum, and Bifidobacterium pseudocatenulatum, were identified to be monophyletic between mother's and infant's intestine. Eleven out of 12 vaginal delivered infants carried at least one monophyletic strain. The bifidobacterial counts of the species to which the monophyletic strains belong, increased predominantly in the infant's intestine within 3 days after birth. Among infants delivered by C-section, monophyletic strains were not observed. Moreover, the bifidobacterial counts were significantly lower than the vaginal delivered infants until 7 days of age.

Conclusions

Among infants born vaginally, several Bifidobacterium strains transmit from the mother and colonize the infant's intestine shortly after birth. Our data suggest that the mother's intestine is an important source for the vaginal delivered infant's intestinal microbiota.

Late-onset neonatal sepsis, risk factors and interventions: an analysis of recurrent outbreaks of Serratia marcescens, 2006-2011

BACKGROUND

Between 2006 and 2011, 11 patients with Serratia marcescens sepsis and 47 patients colonized due to the spread of various clones were observed. These recurrent clusters brought about interventions to reduce spread between patients.

AIM

To evaluate the effect of stepwise interventions to prevent S. marcescens colonization/sepsis and to analyse risk factors for late-onset sepsis (LOS).

METHODS

An open retrospective observational study was performed to evaluate the interventions. A retrospective case-control study was performed to analyse the risk factors for LOS.

FINDINGS

S. marcescens sepsis and colonization decreased after the stepwise adoption of hygiene interventions. Low gestational age, low birth weight, indwelling central venous or umbilical catheter, and ventilator treatment were identified as risk factors for LOS. Compliance with basic hygiene guidelines was the only intervention monitored continuously from late 2007. Compliance increased gradually to a steady high level in early 2009. There was a decrease in S. marcescens LOS, clustering after the second quarter of 2008. After the first quarter of 2009, S. marcescens colonization decreased.

CONCLUSION

It was not possible to identify the specific effects of each intervention, but it is likely that an update of the hospital's antibiotic policy affected the occurrence of S. marcescens LOS. The delayed effect of interventions on S. marcescens colonization was probably due to the time it takes for new routines to have an effect, illustrated by the gradual increase in compliance with basic hygiene guidelines.

Influence of maternal bifidobacteria on the development of gut bifidobacteria in infants

Intestinal microbiota plays an important role in human health by influencing metabolic activities that result in the creation of energy and absorbable nutrients, a barrier to the colonization of pathogens, and stimulation of the immune system. The development of fecal microbiota in neonates is crucial because those bacteria are the first to colonize the sterile intestine of the neonates and, thus, have a significant effect on the host. Initial colonization is also relevant to the final composition of the permanent microbiota in adults. Bifidobacteria are predominant in the fecal microbiota of infants, and, therefore, they are important to an understanding of how commensal bifidobacteria is established in the intestine of infants. While the mother's bifidobacteria are considered to significantly influence the infant's bifidobacteria, it is not clear whether a specific bifidobacterial strain transmits vertically from mother to infant and what factors of the mother before delivery influence the establishment of intestinal bifidobacteria in infants. This review focuses on the impact of maternal bifidobacteria on the development of gut bifidobacteria in the infant and suggests that there is cumulative evidence regarding bifidobacterial transfer from the maternal gut or breast milk to the infant gut.

Beneficial microbes for premature infants, and children with malignancy undergoing chemotherapy

This review reports the beneficial effects, observed in our clinical studies, of Bifidobacterium breve for premature infants, and children with cancers undergoing chemotherapy. To investigate the protective effects of B. breve (M-16V) as a probiotic on necrotizing enterocolitis (NEC) and infection in premature infants, we carried out a clinical study in 338 very low birth weight infants over a five-year period. These patients were supplemented with B. breve starting several hours after birth (Bifido group). 226 premature infants served as controls. Infants of the Bifido group were administered B. breve in a daily dose of 1×10(9) cells/day. The incidence of NEC was significantly reduced in the Bifido group (nil) compared with that in controls (6 cases, P<0.01). Infection also decreased significantly. Thus, administration of B. breve as a probiotic looks to be a very effective treatment for preventing NEC and infection in preterm infants. Mucositis, also referred to as mucosal barrier injury, is one of the most debilitating side effects of chemotherapy treatment. To evaluate the effects of the administration of B. breve (BBG-01, another strain than that used in the study of premature infants), a clinical study was performed to ascertain whether it attenuated intestinal mucositis in children with cancers on chemotherapy. A placebo-controlled trial was performed in patients with malignancies admitted for chemotherapy (n=42), who were randomised into two groups receiving probiotic or placebo. The frequency of fever and the use of intravenous antibiotics were significantly lower in the Bifido group than the placebo group. The B. breve administration enhanced the colonisation of anaerobes. Disruption of the intestinal microbiota after chemotherapy, such as the increase in the population levels of Enterobacteriaceae, was more pronounced in the placebo group. In conclusion, these data suggest that administration of B. breve is an effective approach to attenuating chemotherapy-induced mucositis in children with cancers. The study results strongly suggest that B. breve administration as a probiotic is an effective therapy for the prevention of NEC and infection in premature infants, and also a promising treatment for attenuating chemotherapy-induced mucositis in children with cancers.

Simple strategies to reduce healthcare associated infections in the neonatal intensive care unit: line, tube, and hand hygiene

This article describes strategies to prevent 2 important healthcare associated infections in the neonatal intensive care unit: central line-associated bloodstream infections and catheter-associated urinary tract infections. Hand hygiene is discussed as the cornerstone for prevention of all healthcare associated infections. Specific recommendations for education and training of health care personnel who insert and maintain central venous catheters and urinary tract catheters are made and best practices for insertion and maintenance of these catheters are discussed. Throughout this article, the emphasis is on prevention of these high morbidity and mortality healthcare associated infections.

Tetracycline-resistant Escherichia coli strains are inherited from parents and persist in the infant's intestines in the absence of selective pressure

The study investigated tetracycline (TC), ampicillin (AMP), cefazolin (CEF), and trimethoprim (TMP) resistance in Escherichia coli (E. coli) in the feces of 21 infants up to 6 months of age and in their parents in the absence of selective antimicrobial pressure. Clonality of strains was assessed by pulsed-field gel electrophoresis. Three infants had resistant E. coli strains in their feces identical to the mothers' from week 1 on, which persisted over weeks. From week 2 on, in another four infants, persisting resistant E. coli were found, two of them identical to the mothers'. All of these persisting E. coli strains (except one family) showed at least resistance to TC. In infants, resistant E. coli strains inherited from their mothers tended to persist over months. Therefore, the persistence of resistant E. coli and their possible capacity to cause symptomatic infection or transfer its resistance genes to other bacteria deserves more attention.

Detection of intestinal bifidobacteria and lactobacilli in patients with Hirschsprung's disease associated enterocolitis

BACKGROUND

The etiology of Hirschsprung's disease associated enterocolitis (HAEC) is unknown. Previous investigations have suggested that several factors such as dilation of proximal bowel, changes in colonic mucosal defence, and overgrowth of toxigenic bacteria may be related with it. This study was to quantify bifidobacteria and lactobacilli in the feces of Hirschsprung's disease (HD) patients with or without enterocolitis and those of normal children.

METHODS

Fresh stool specimens were collected at the first three days of the admission from 30 HD patients (aged 2 weeks to 2 years) and 15 healthy age-matched non-HD patients in the morning once a day for at least three days. All of them have not been given probiotics or antibiotics at least 7 days before stool collection. Hematoxylin-eosin and acetylcholinesterase histochemical staining on rectal biopsies of patients with HD confirmed the diagnosis of HD in all 30 patients. The 30 HD patients were divided into two groups based on the clinical history of enterocolitis: the HAEC group (n=10) and HD group (n=20). Fecal bifidobacteria and lactobacilli were consecutively quantified by SYBR Green I-based real-time PCR assay. Data were analyzed using SAS v. 12.6 for Windows. All tests were two-tailed, and P values <0.05 were considered statistically significant.

RESULTS

The mean levels of bifidobacteria were 7.35+/-0.59, 8.16+/-1.17, and 8.35+/-0.74 in the HAEC, HD and control groups, respectively. The bifidobacteria colonization levels were lower in the HAEC group than in the HD and control groups (P<0.05, P<0.001 respectively). The mean level of lactobacilli in the HAEC (5.51+/-0.65) and HD groups (5.87+/-0.78) was significantly lower than that in the control group (6.39+/-0.56) (P<0.05). But there was no difference in log numbers of lactobacilli between HAEC and HD groups (P>0.05).

CONCLUSIONS

The scarcity of bifidobacteria and lactobacilli in HAEC patients may result in a decrease in epithelial barrier function and be a predisposing factor in the development of HAEC. This decline suggests that treatment with probiotics or prebiotics may be beneficial in these individuals. Further research will focus on whether probiotics can decrease the incidence of HAEC.

Influence of maternal bifidobacteria on the establishment of bifidobacteria colonizing the gut in infants

The aim of this study was to examine the influence of maternal intestinal and vaginal bifidobacteria on the establishment of bifidobacteria colonizing the gut in infants. Fecal samples from 110 healthy pregnant mothers within 1 mo before delivery and their babies at 1 mo of age and 100 vaginal swabs from the mother within 7 d before delivery were collected at a maternity hospital in Fukuoka city, Japan. The fecal and vaginal samples were assayed by PCR to detect Bifidobacterium species and by real-time PCR assays to estimate the bifidobacterial number. The detection of Bifidobacterium breve in the mothers' feces was significantly associated with increases in both the bifidobacterial counts and number of Bifidobacterium species in the babies' feces. In addition, a cesarean section was significantly associated with both a decrease in the counts and diversity of bifidobacteria in the babies' feces. The number of Bifidobacterium species detected in the vaginal swabs of mothers were not associated with either the bifidobacterial counts or the diversity of bifidobacteria in the babies' feces. The most important determinants of intestinal bifidobacteria in infants were the colonization of B. breve in the mothers' gut and vaginal delivery.

Establishment of the gut microbiota in Western infants

In adult individuals, the intestinal microbiota comprises several hundred, mostly anaerobic, bacterial species. This complex ecosystem is formed through the successive establishment of different bacteria in infancy and early childhood. Facultative and aerotolerant bacteria establish first, followed by more and more strict anaerobes. The bacteria derive from different sources and the colonization pattern is influenced by delivery mode and environmental factors. Commensal microbes provide the major drive for maturation of the immune system. Increased hygiene appears to have changed the gut flora of Western infants, which may affect the risk of developing immune mediated diseases.

CONCLUSION

It is clear that the process of infant colonization needs to be studied further, since composition of the microbiota may impact on child health.

Maternal breast-milk and intestinal bifidobacteria guide the compositional development of the Bifidobacterium microbiota in infants at risk of allergic disease

BACKGROUND

The sources and the impact of maternal bacteria on the initial inoculum of the intestinal microflora of newborn infants remain elusive.

OBJECTIVE

To assess the association between maternal breast-milk and fecal bifidobacteria and infants' fecal bifidobacteria.

METHODS

Sixty-one mother-infant pairs were included, special emphasis being placed on the maternal allergic status. Bifidobacteria were analysed by a direct PCR method in fecal samples from mothers at 30-35 weeks of gestation and from infants at 1 month of age and from breast-milk samples 1 month post-partum.

RESULTS

Fecal Bifidobacterium adolescentis and Bifidobacterium bifidum colonization frequencies and counts among mother-infant pairs correlated significantly (P=0.005 and 0.02 for frequencies, respectively, and P=0.002 and 0.01 for counts, respectively). Only infants of allergic, atopic mothers were colonized with B. adolescentis. Each of the breast-milk samples contained bifidobacteria [median 1.4 x 10(3) bacterial cells/mL; interquartile range (IQR) 48.7-3.8 x 10(3)]. Bifidobacterium longum was the most frequently detected species in breast-milk. Allergic mothers had significantly lower amounts of bifidobacteria in breast-milk compared with non-allergic mothers [median 1.3 x 10(3) bacterial cells/mL (IQR 22.4-3.0 x 10(3)) vs. 5.6 x 10(3) bacterial cells/mL (1.8 x 10(3)-1.8 x 10(4)), respectively, (P=0.004)], and their infants had concurrently lower counts of bifidobacteria in feces [3.9 x 10(8) bacterial cells/g (IQR 6.5 x 10(6)-1.5 x 10(9)) in infants of allergic mothers, vs. 2.5 x 10(9) bacterial cells/g (6.5 x 10(8)-3.2 x 10(10)) in infants of non-allergic mothers, P=0.013].

CONCLUSIONS

Breast-milk contains significant numbers of bifidobacteria and the maternal allergic status further deranges the counts of bifidobacteria in breast-milk. Maternal fecal and breast-milk bifidobacterial counts impacted on the infants' fecal Bifidobacterium levels. Breast-milk bacteria should thus be considered an important source of bacteria in the establishment of infantile intestinal microbiota.

Development of intestinal bifidobacteria and lactobacilli in breast-fed neonates

BACKGROUND & AIMS

Neonates are subject to numerous factors that affect normal intestinal colonization. This study was to quantify bifidobacteria and lactobacilli in the faeces of breast-fed neonates using quantitative real-time PCR assay, and to investigate the effects of different delivery on the development of bifidobacteria or lactobacilli.

METHODS

The faecal bifidobacteria and lactobacilli of 40 healthy breast-fed neonates were studied prospectively. Twenty infants were vaginally delivered (VD), and 20 by caesarean delivery (CD) with prophylactically 4 g intravenous cefradine administered to their mothers three times. The faecal bifidobacteria and lactobacilli of neonates were consecutively quantified by SYBR Green I-based real-time PCR assay in the first 7 days after birth.

RESULTS

The mean levels of bifidobacteria increased from 5.1 to 9.3 in the VD group vs from less than 4.6 to 8.7 in the CD group. The bifidobacteria colonization levels in six samples in the CD group were lower than the limit of detection on day 2. The mean levels of bifidobacteria in the VD group were significantly higher than in the CD group (p<0.05). The mean levels of lactobacilli increased from 4.9 to 7.2 in the VD group vs from 4.9 to 6.9 in the CD group. There was no statistical difference between two groups during the first week (p>0.05). The development of bifidobacteria and lactobacilli showed significant interindividual differences in all infants studied.

CONCLUSIONS

Primary intestinal bifidobacteria in neonates by caesarean may be disturbed more significantly than lactobacilli.

Outbreaks in neonatal intensive care units - they are not like others

BACKGROUND

Outbreaks of health care-associated infections in neonatal intensive care units (NICUs) are frequent and have received more attention in medical literature than outbreaks from other types of intensive care units (ICUs). The objective of this systematic review was to identify differences between outbreaks of health care-associated infections in NICUs and other ICUs as reported to date in the medical literature.

METHODS

Screening the outbreak database (http://www.outbreak-database.com), a systematic comparison of outbreaks was performed with the following categories: causing pathogen, type of infection, sources identified, and measures taken to stop the outbreak.

RESULTS

Two hundred and seventy-six outbreaks were reported from NICUs and 453 from other ICU types. Enterobacteriaceae were significantly more often responsible for NICU outbreaks, whereas nonfermenting bacteria are more frequently identified in other ICU types. On average, 23.9 patients and 1.8 health care workers were involved in NICU outbreaks. Average mortality in NICU outbreak was 6.4% (1.5 newborns on average). In 48.6% of NICU outbreaks the authors were unable to identify the sources compared with 38.0% in other ICU outbreaks. The most important infection control measures were significantly more often implemented in NICUs than in other ICUs.

CONCLUSIONS

Systematic outbreak analysis is essential for gaining insights into the control of NICU outbreaks.

Reduced enterobacterial and increased staphylococcal colonization of the infantile bowel: an effect of hygienic lifestyle?

The modern Western lifestyle may have altered the composition of the commensal microflora. Here, we investigated the first year's intestinal colonization pattern in 99 vaginally delivered Swedish infants and 17 delivered by cesarean section. Rectal swabs obtained at 3 d of age were cultured for aerobic bacteria and fecal samples obtained at 1, 2, 4, and 8 wk and at 6 and 12 mo of age were cultivated quantitatively for aerobic and anaerobic bacteria. Vaginally delivered infants more often had Escherichia coli compared with cesarean section-delivered infants, whereas the latter more frequently carried other enterobacteria, such as Klebsiella and Enterobacter. Independent of delivery mode, it took 2 mo until most infants were colonized by enterobacteria, traditionally the first colonizers. In contrast, coagulase-negative staphylococci colonized 99% of the infants from d 3 onwards. The poor adaptation of staphylococci to the gut was shown by declining population sizes after some weeks. Dominating anaerobes were initially bifidobacteria and clostridia, whereas Bacteroides initially colonized only 30% of vaginally delivered infants and increased very slowly in prevalence. Bacteroides colonization was delayed up to 1 y in cesarean section-delivered compared with vaginally delivered infants. Our results show that some "traditional" fecal bacteria are acquired late today especially in cesarean section-delivered infants, probably due to limited environmental circulation. In their absence, skin bacteria like staphylococci have become the first gut colonizers.

Effects of bifidobacterium breve supplementation on intestinal flora of low birth weight infants

BACKGROUND

It is known that the bifidobacteria flora play important roles in mucosal host defense and can prevent infectious diseases. Because bacterial populations develop during the first day of life, the authors examined whether the early administration of bifidobacteria has a positive effect on the health of low birth weight infants.

METHODS

The effects of oral administration of Bifidobacterium breve (B. breve) supplements were studied in a controlled trial with low birth weight infants (average birth weight 1489 g). The infants were divided into three groups: Group A and B received a dose of 1.6 x 10(8) cells of B. breve supplement twice a day, commencing either from several hours after birth (group A) or 24 h after birth (group B). Group C, the control group, received no supplement.

RESULTS

There were no significant differences in birth weight, treatment with antibiotics, and the starting time of breast-feeding among the three groups. A Bifidobacterium-predominant flora was formed at an average of 2 weeks after birth in group A and at an average of 4 weeks after birth in group B, while no Bifidobacterium was isolated in eight out of 10 infants in group C during the observation period of 7 weeks. In comparison between group A and B, Bifidobacterium was detected significantly earlier in group A, and the number of Enterobacteriaceae present in the infants at 2 weeks after birth was significantly lower in group A.

CONCLUSION

The results of the present study suggest that very early administration of B. breve to low birth weight infants is useful in promoting the colonization of the Bifidobacterium and the formation of a normal intestinal flora.

Prevalence of colonisation with third-generation cephalosporin-resistant Enterobacteriaceae in ICU patients of Heidelberg University Hospitals

The aim of this study was to assess colonisation and transmission of third-generation cephalosporin-resistant Enterobacteriaceae (CRE) from patients in 16 intensive care units. A prospective, repetitive point prevalence survey was performed over 6 months, involving samples from 1851 patients. CRE were isolated from 186 (10%) patients, with Enterobacter spp. being the most common. Mean point prevalence rates were significantly higher for paediatric wards (22.5%) compared to surgical (8.1%) and medical (5.5%) units. All CRE isolates were typed by pulsed-field gel electrophoresis. Non-outbreak nosocomial transmission rates of these pathogens were calculated as 12.8% for paediatric patients, compared to 6.8% for adult patients, which may reflect differences in sensitivity to overgrowth with resistant bacteria and contact with health care workers.

Escherichia coli in infants' intestinal microflora: colonization rate, strain turnover, and virulence gene carriage

Colonization by Escherichia. coli in infants might have decreased in the last decades, owing to changes in hospital routines and family lifestyle. In this study, the E. coli flora was characterized in 70 healthy Swedish infants followed for the first year of life. E. coli was isolated from rectal swabs obtained at 3 d of age and quantified in fecal samples collected at 1, 2, 4, and 8 wk of age and at 6 and 12 mo of age. Strains were typed using random amplified polymorphic DNA, and their virulence factor genes were identified by multiplex PCR. Colonization by E. coli occurred late; only 61% of the infants were positive by 2 mo of age. The turnover of individual strains in the microflora was slow (1.5 strains per infant during 6 mo, 2.1 during 1 y). Environmental factors, such as siblings, pets, or feeding mode, did not influence colonization kinetics or strain turnover rate. Genes encoding type 1 fimbriae, P fimbriae, and hemolysin were significantly more common in E. coli strains persisting for at least 3 wk in the microflora than in transient strains. The P-fimbrial class III adhesin gene was more common in E. coli from children who had a cat in their homes than in E. coli from children without pets (p = 0.01); this adhesin type is common in E. coli from cats. The late colonization and low E. coli strain turnover rate suggest limited exposure of Swedish infants to E. coli. Our results confirm that P fimbriae and other virulence factors facilitate persistence of E. coli in the human colonic microflora.

Risk factors for hospital-acquired infections in the neonatal intensive care unit

Infants in the neonatal intensive care unit (NICU) have many risk factors for infection. Compared with older children and adults, infants, particularly premature infants, are relatively immunocompromised. Patients in the NICU have intrinsic risk factors for infections due to immunological "deficiencies" or inadequate development of mechanical barriers such as skin and gastrointestinal tract mucosa. Like other ICU populations, NICU patients have extrinsic risk factors for infection such as prolonged hospitalization, invasive procedures, instrumentation, medical treatments and concomitant medical conditions. Compared with healthy full-term infants, patients in the NICU develop abnormal flora, which is generally acquired in the NICU from patient-to-patient transmission via hand carriage of healthcare workers. This flora is frequently multidrug-resistant as it has developed under the selective pressure of antibiotics and can cause invasive disease. An understanding of the risk factors that are associated with hospital-acquired infections is essential to design preventive strategies.

Molecular epidemiological study of vertical transmission of vaginal Lactobacillus species from mothers to newborn infants in Japanese, by arbitrarily primed polymerase chain reaction

We investigated mother-to-newborn infant transmission of Lactobacillus species in Japanese by the typing of isolates from the vagina of pregnant women and stool specimens from their newborn infants. All infants were born by uncomplicated vaginal delivery and were basically fed breast milk. Lactobacillus strains were fingerprinted by arbitrarily primed polymerase chain reaction (AP-PCR), using ERIC1R and ERIC2 primers. Of 86 pregnant women tested, 71 (82.6%) were positive for vaginal lactobacilli. At 5 days after birth, 24 (33.8%) of the 71 infants whose mothers were lactobacilli-positive had fecal lactobacilli, while only 1 (6.7%) of the 15 infants delivered from the vaginal lactobacilli-negative mothers was lactobacilli-positive ( P < 0.01). Lactobacillus crispatus was the most prevalent species of vaginal lactobacilli in mothers and of fecal lactobacilli in infants at 5 days of age, whereas Lactobacillus gasseri was the most common in infants at 1 month of age. Identification to the species level, followed by AP-PCR typing, demonstrated that 23.3% of the 86 infants were likely to be colonized in the intestine by the vaginal lactobacilli of their mothers, and that only 2 of the infants retained the same vaginal lactobacilli until 1 month of age. These results suggest that approximately one-fourth of infants acquire vaginal lactobacilli from their mothers at birth, and that the acquired lactobacilli do not last in the intestine of the infant long-term, but rather, are replaced by ones from milk or unknown sources after birth. AP-PCR with primers ERIC1R and ERIC2 is indicated as a potential tool for the typing of Lactobacillus strains.

Breast feeding and the intestinal microflora of the infant--implications for protection against infectious diseases

Human breast milk contains an array of factors with anti-infectious potential, such as immunoglobulins (especially secretory IgA), oligosaccharides and glycoproteins with anti-adhesive capacity, and cytokines. Breast-feeding is associated with protection from the following infections or infection-related conditions: gastroenteritis, upper and lower respiratory tract infection, acute otitis media, urinary tract infection, neonatal septicaemia and necrotizing enterocolitis. Some of the protective effects may derive from an altered mucosal colonization pattern in the breast-fed infant. In other instances breast-fed infants develop less symptoms to the same microbe which causes disease in the bottle-fed infant. An example of an altered colonization pattern is that breast-fed infants have less P-fimbriated, but more type 1-fimbriated E. coli. This may protect against urinary tract infection in the breast-fed infant since P. fimbriae are the major virulence factor for urinary tract infection. An example of changed consequences of the same microbial colonization is that secretory IgA in the breast-milk protects very efficiently from translocation of intestinal bacteria across the gut mucosa by coating intestinal bacteria and blocking their interaction with the epithelium. This mechanism may protect the infant from septicaemia of gut origin and, possibly, necrotizing enterocolitis. Breast-milk is also highly anti-inflammatogenic and contains hormone like factors which counteract diarrhea. Thus, breast-fed infants may be colonized by recognized diarrheal pathogens and still remain healthy. Due to a less virulent intestinal microflora and decreased translocation breast-fed infants will obtain less stimuli for the gut immune system, resulting, in e.g., lower salivary IgA antibody titres.

Clinical assay of N-duopropenide alcohol solution on hand application in newborn and pediatric intensive care units: control of an outbreak of multiresistant Klebsiella pneumoniae in a newborn intensive care unit with this measure

Outbreaks of gram-negative colonization (generally by antibiotic-resistant enterobacteria) are common in newborn intensive care units (NICUs), and control methods are not always effective. We studied the effectiveness of an alcohol solution of N-duopropenide (NDP) in vivo (germicidal effect on flora of teams in the NICU and the pediatric intensive care unit vs handwashing with nonantiseptic soap) and its effect on the control of a multiresistant (MR) Klebsiella pneumoniae outbreak in our NICU that had persisted for 13 months, despite the use of classic control measures. For educational purposes, we also performed 4 prevalence studies of microbial hand flora in NICU staff (two before and two after introducing NDP). The alcohol solution of NDP was highly germicidal in vivo, destroying microorganisms better than classic handwashing on the hands of 69 health care staff of our NICU and PICU. The flora in both units was reduced from an average of 63% to an average of 95%. Application of this disinfectant to the hands of health care workers after handling newborns helped to eliminate the MR Klebsiella strain in our NICU, (relative risk compared with the period preceding use of the disinfectant: 8.6, with 95% confidence intervals, 4.8-145.5). Four prevalence studies of hand microbial contamination, before and after NDP introduction in the NICU, showed a significant reduction of enterobacteriaceae, mainly MR K pneumoniae, in health care workers. In conclusion, NDP in alcohol was very effective in vivo. It proved to be a useful complementary measure to handwashing and reduced exogenous microorganism transmission in a unit with a heavy patient-care workload.

Nosocomial colonization of premature babies with Klebsiella oxytoca: probable role of enteral feeding procedure in transmission and control of the outbreak with the use of gloves

OBJECTIVE

To investigate the persistence of colonization of premature babies by Klebsiella oxytoca, with special emphasis on the mode of transmission of the bacterium and evaluation of Standard Precautions to stop the epidemic.

DESIGN

Retrospective analysis of cases and prospective study of systematic bacteriological samples (stools and throat) from babies, healthcare workers (HCWs), and environment, with genotyping of strains by arbitrarily primed polymerase chain reaction.

SETTING

A premature baby unit (PBU) and a neonatal intensive care unit in the university hospital of Saint-Etienne, France.

RESULTS

An outbreak of K oxytoca was suspected in two pediatric wards after the occurrence of a fatal bacteremia in a newborn hospitalized in the PBU and the colonization of other babies 2 months later. Retrospective analysis showed that 24 babies' digestive tract had been colonized. No environmental reservoir was recovered in the units nor in enteral feeding. No K oxytoca was isolated from HCW samples. Genotyping confirmed the presence of epidemic strains, although independent clones were responsible for infections or colonizations in each of the two units. The chronology and the site of babies' colonization (isolation of K oxytoca in stools before throat) were determined during a prospective study and suggested that enteral feeding procedures could be the source of contamination. Therefore, use of gloves during this practice by HCWs was recommended and, after readjustment of Standard Precautions, stopped the outbreak.

CONCLUSION

To prevent cross-contamination among high-risk babies, careful attention must be paid to Standard Precautions. Bacteriological surveillance of the digestive tract of neonates could help to check compliance with these guidelines

Influence of breastmilk on the development of resistance to intestinal colonization in infants born at the Atma Jaya Hospital, Jakarta

A study of intestinal colonization resistance (CR) in breastfed versus formula-fed newborns at 4 intervals after birth in Jakarta, Indonesia, is described. To measure the intestinal CR for gram-negative enterobacilli, mean values of Enterobacteriaceae concentrations and mean numbers of Enterobacteriaceae biotypes were determined. The CR values found in this study show, that in all 4 sampling periods, at < 1, 2, 4 and 6 months, the mean concentration of Enterobacteriaceae was somewhat lower in the breastfed group than in the formula-fed group (only significant at 6 months). This means that the intestinal CR of the breastfed group may have been slightly higher than that in the formula-fed group. In both study groups, the CR was lower in the second and fourth month than soon after birth and at 6 months. For epidemiological reasons, comparison was performed of the Enterobacteriaceae biotypes found in samples from mother and child. The data show that, in the first sampling period, regardless of the theoretical possibility of a 'more intense (skin) contact' during breastfeeding (which might promote transfer of also microorganisms), the breastfed infants had a significantly lower percentage of identical Enterobacteriaceae biotypes than did the formula-fed group. This could possibly be ascribed to a higher CR in the breastfed group. Determination of the concentration of Enterococcus species was found applicable to reproducibly measure the CR in the newborns at 6 months and in the mother-group.

Fecal microflora in healthy infants born by different methods of delivery: permanent changes in intestinal flora after cesarean delivery

BACKGROUND

Newborn infants in modern maternity hospitals are subject to numerous factors that affect normal intestinal colonization--for example, cesarean delivery and antimicrobial agents. To study the duration of the effect of external factors on intestinal colonization, two groups of infants with different delivery methods were investigated.

METHODS

The fecal flora of 64 healthy infants was studied prospectively. Thirty-four infants were delivered vaginally, and 30 by cesarean birth with antibiotic prophylaxis administered to their mothers before the delivery. The fecal flora was cultured on nonselective and selective media in infants 3 to 5, 10, 30, 60, and 180 days of age. Gastrointestinal signs were recorded daily by the mothers for 2 months.

RESULTS

The fecal colonization of infants born by cesarean delivery was delayed. Bifidobacterium-like bacteria and Lactobacillus-like bacteria colonization rates reached the rates of vaginally delivered infants at 1 month and 10 days, respectively. Infants born by cesarean delivery were significantly less often colonized with bacteria of the Bacteroides fragilis group than were vaginally delivered infants: At 6 months the rates were 36% and 76%, respectively (p=0.009). The occurrence of gastrointestinal signs did not differ between the study groups.

CONCLUSIONS

This study shows for the first time that the primary gut flora in infants born by cesarean delivery may be disturbed for up to 6 months after the birth. The clinical relevance of these changes is unknown, and even longer follow-up is needed to establish how long-lasting these alterations of the primary gut flora can be.

Epidemiology and attack index of gram-negative bacteria causing invasive infection in three special-care neonatal units and risk factors for infection

Of 13 consecutive episodes of gram-negative septicemia (Escherichia coli eight, Klebsiella oxytoca four, Klebsiella pneumoniae one) among 113 infants in three special-care neonatal units studied, five episodes were epidemiologically related according to a novel fingerprinting method for enterobacteria. In ten episodes the invasive phenotype was found in the fecal flora of up to 54% of the fellow infants in the same ward and for periods of up to 70 days. Two units exchanged patients, which further promoted the transmission of invasive strains. The attack index was highest for certain E. coli strains, generally low for K. oxytoca strains, but lowest for other E. coli strains. The infants contracting septicemia had lower birth weight (p = 0.04) or were more often classified as high-risk infants than matched non-infected fecal carriers of the invasive strains (p = 0.04). In summary, gram-negative neonatal septicemia was either due to an apparently high-virulent strain capable of attacking the single full-term infant carrier or a high-colonizing phenotype of lower apparent virulence, which occasionally attacked a high-risk infant among a large number of infants colonized.

Survival on skin and surfaces of epidemic and non-epidemic strains of enterobacteria from neonatal special care units

It has been suggested that increased ability to survive on the hands of hospital staff contributes to transmission of certain strains of Gram-negative bacteria. We tested this hypothesis by comparing the survival on fingertips, glass slides and membrane filters of epidemic (M, major) and matched non-epidemic (S, sporadic) faecal strains of Escherichia coli (n = 13 vs. 13) and Klebsiella spp. (n = 19 vs. 19) found among 1066 neonates in 25 special care units (SCUs). The time to 50% killing at 22 degrees C in air was longer for E. coli than for Klebsiella spp. both on human skin (median 6 vs. 2 min P < 0.001) and glass surfaces (15 vs. 8 min P < 0.001). On the other hand, Klebsiella spp. were superior to E. coli in long-term survival tests on membrane filters expressed as the minimum inoculum still yielding growth after 10 days exposure at 22 degrees C in air (10(5) vs. 10(8) bacteria P < 0.001). Despite a large variation in survival times between individual strains no differences between M strains and S strains were observed in any of the three tests. This indicates that bacterial properties other than survival on surfaces contribute to the increased capacity for transmission of certain strains of enterobacteria in SCUs.