The stepwise assembly of the neonatal virome is modulated by breastfeeding.

The gut of healthy human neonates is usually devoid of viruses at birth, but quickly becomes colonized, which-in some cases-leads to gastrointestinal disorders1-4. Here we show that the assembly of the viral community in neonates takes place in distinct steps. Fluorescent staining of virus-like particles purified from infant meconium or early stool samples shows few or no particles, but by one month of life particle numbers increase to 109 per gram, and these numbers seem to persist throughout life5-7. We investigated the origin of these viral populations using shotgun metagenomic sequencing of virus-enriched preparations and whole microbial communities, followed by targeted microbiological analyses. Results indicate that, early after birth, pioneer bacteria colonize the infant gut and by one month prophages induced from these bacteria provide the predominant population of virus-like particles. By four months of life, identifiable viruses that replicate in human cells become more prominent. Multiple human viruses were more abundant in stool samples from babies who were exclusively fed on formula milk compared with those fed partially or fully on breast milk, paralleling reports that breast milk can be protective against viral infections8-10. Bacteriophage populations also differed depending on whether or not the infant was breastfed. We show that the colonization of the infant gut is stepwise, first mainly by temperate bacteriophages induced from pioneer bacteria, and later by viruses that replicate in human cells; this second phase is modulated by breastfeeding.

HIV-exposure, early life feeding practices and delivery mode impacts on faecal bacterial profiles in a South African birth cohort.

There are limited data on meconium and faecal bacterial profiles from African infants and their mothers. We characterized faecal bacterial communities of infants and mothers participating in a South African birth cohort. Stool and meconium specimens were collected from 90 mothers and 107 infants at birth, and from a subset of 72 and 36 infants at 4-12 and 20-28 weeks of age, respectively. HIV-unexposed infants were primarily exclusively breastfed at 4-12 (49%, 26/53) and 20-28 weeks (62%, 16/26). In contrast, HIV-exposed infants were primarily exclusively formula fed at 4-12 (53%; 10/19) and 20-28 weeks (70%, 7/10). Analysis (of the bacterial 16S rRNA gene sequences of the V4 hypervariable region) of the 90 mother-infant pairs showed that meconium bacterial profiles [dominated by Proteobacteria (89%)] were distinct from those of maternal faeces [dominated by Firmicutes (66%) and Actinobacteria (15%)]. Actinobacteria predominated at 4-12 (65%) and 20-28 (50%) weeks. HIV-exposed infants had significantly higher faecal bacterial diversities at both 4-12 (p = 0.026) and 20-28 weeks (p = 0.002). HIV-exposed infants had lower proportions of Bifidobacterium (p = 0.010) at 4-12 weeks. Maternal faecal bacterial profiles were influenced by HIV status, feeding practices and mode of delivery. Further longitudinal studies are required to better understand how these variables influence infant and maternal faecal bacterial composition.

Fetal peritonitis due to appendiceal rupture: a rare complication of hydrops.

A rare complication (appendiceal perforation with meconium peritonitis) was observed in a second trimester fetus affected by nonimmune fetal hydrops due to parvovirus B-19 infection. The complication is not considered specific to this or any other etiology for hydrops, which is highly heterogeneous; rather it is an expression of the fragility and friability of edematous tissues.

Detection of cytomegalovirus in the meconium of infected newborns by polymerase chain reaction.

OBJECTIVE: Congenital cytomegalovirus (CMV) infection is a leading cause of hearing loss and mental retardation throughout the world. Detection of the CMV DNA by polymerase chain reaction (PCR) offers a sensitive, rapid, and specific means of identification. Meconium, the stool formed in utero, may be an ideal specimen for CMV detection. The objective of this study was to develop a PCR-based methodology for the detection of CMV in the meconium of neonates. METHODS: Meconium was collected from 10 newborn infants (seven with positive viral cultures and three uninfected infants born to CMV-seropositive mothers). For each, DNA was isolated from meconium by organic extraction and attachment to a DNA-binding matrix, and PCR was performed using amplimers specific for the major intermediate early (MIE) and late antigenic (LA) regions of CMV. RESULTS: Gel electrophoresis demonstrated an anticipated PCR product of 250 base pairs (bp) corresponding to the MIE region of CMV in all infected and positive control meconium samples. Furthermore, a single band of 150 bp corresponding to the LA region of CMV was also amplified in several of the infected infants. Conversely, no amplification of these antigenic regions was noted in either uninfected infants born to CMV-seropositive mothers or negative controls. CONCLUSIONS: CMV is present within the meconium of infected neonates and is readily detectable by PCR.