Prospective assessment of the gastroesophageal microbiome in VLBW neonates

Abstract

BackgroundThe distal GI microbiota of hospitalized preterm neonates has been established to be unique from that of healthy full-term infants; the proximal GI, more specifically gastroesophageal colonization has not been systematically addressed. We prospectively evaluated early colonization of gastroesophageal portion of the GI tract of VLBW infants.MethodsThis study involved 12 infants admitted to a level III NICU with gestational age (GA) 27 +/− 0.5 weeks and birth weight 1105 +/− 77 grams. The gastroesophageal microbial flora was evaluated using 16S rDNA analysis of aspirates collected in a sterile manner during the first 28 days of life.ResultsBacteria were detected in 9 of the 12 neonates. Ureaplasma was the dominant species in the first week of life, however, staphylococci were the predominant bacteria overall. By the fourth week, Gram (−) bacteria increased in abundance to account for 50% of the total organisms. Firmicutes were present in the majority of the neonates and persisted throughout the 4 weeks comprising nearly half of the sequenced clones. Noticeably, only two distinct species of Staphylococcus epidermidis were found, suggesting acquisition from the environment.ConclusionsIn our neonates, the esophagus and stomach environment changed from being relatively sterile at birth to becoming colonized by a phylogenetically diverse microbiota of low individual complexity. By the fourth week, we found predominance of Firmicutes and Proteobacteria. Bacteria from both phyla (CONS and Gram (−) organisms) are strongly implicated as causes of hospital-acquired infections (HAI). Evaluation of the measures preventing colonization with potentially pathogenic and pathogenic microorganisms from the hospital environment may be warranted and may suggest novel approaches to improving quality in neonatal care.

The microbiome, parturition, and timing of birth: more questions than answers

“…Additionally, our own lab has found that the placenta harbors a unique microbiome, and that this microbiome differs in term and preterm subjects (Figure 1) (Aagaard et al, 2014). Supporting our observations, a bacterium found in the amniotic fluid of preterm patients was most likely to be found in the oral cavity as well, rather than the vaginal cavity (Bearfield, 2002; Douvier et al, 1999; Han et al, 2006) and both term and preterm neonates appear to be colonized early with bacteria normally found in the oral cavity (Figure 1) (Human Microbiome Project Consortium, 2012; Jost et al, 2012; Milisavljevic et al, 2013; Palmer et al, 2007). When Fusobacterium nucleatum is isolated from preterm patients and injected intravenously into pregnant mice, the placenta becomes selectively colonized with bacteria while other organs, such as the liver or spleen, do not (Han et al, 2004).…”

Nasogastric feeding tubes from a neonatal department yield high concentrations of potentially pathogenic bacteria— even 1 d after insertion

“…The total number of bacteria decreased over the first 4 wk in one study where Bacteroides and Escherichia coli were predominant (14). On the contrary, in another study, the total number of bacteria increased and Staphylococcus epidermidis was the main colonizer (15). Duodenal aspirates from preterm infants contained none or few Gram-positive bacteria in the first days of life with increasing probability of colonization with Staphylococci, Enterococci, and Gram-negative bacteria, especially Escherichia coli, and Klebsiella pneumoniae and K. oxytoca, over the first weeks.…”

“…Only few groups have investigated the early colonization of the upper part of the gastrointestinal tract in preterms, but they found that the microbiomes of gastric aspirates are unstable and consisting of low bacterial counts (14)(15)(16). The total number of bacteria decreased over the first 4 wk in one study where Bacteroides and Escherichia coli were predominant (14).…”

The Perinatal Microbiome and Pregnancy: Moving Beyond the Vaginal Microbiome

“…In this study, the authors found that healthy, term neonates that were breast fed had increased diversity in their intestinal microbiome when compared with hospitalized, preterm infants using PCR-DGGE analysis (Schwiertz et al 2003). Additional studies have confirmed that the microbiome of infants with conditions like PTB, very low birth weight infants, or necrotizing enterocolitis, also have an altered microbiome (Schwiertz et al 2003; Hällström et al 2004; Milisavljevic et al 2013; Wang et al 2013). However, it is unclear if these alterations are caused by early gestational age at delivery or hospitalization because neonatal exposure in early life is pertinent to the establishment of the microbiome.…”