The Effect of Meconium Staining of Amniotic Fluid on the Growth of Escherichia coli and Group B Streptococcus

Eidelman, Arthur I.; Nevet, Ayelet; Rudensky, Bernard; Rabinowitz, Ron; Hammerman, Cathy; Raveh, David; Schimmel, Michael S.

doi:10.1038/sj.jp.7210774

Cited by 37 publications

(21 citation statements)

References 25 publications

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“…40 Blood culture positive sepsis was seen in 3 infants in the suction group (2 Escherichia coli and 1 Serratia marcescens) and 5 infants in no-suction group (3 E coli, 1 S marcescens, and 1 Staphylococcus aureus). Increased isolation of E coli and S aureus in MSAF compared with clear liquor was described previously by Eidelman et al 41 The risk of secondary pneumonia and culture positive sepsis did not decrease by suctioning of meconium from trachea.…”

Section: Discussionmentioning

confidence: 63%

Endotracheal Suction for Nonvigorous Neonates Born through Meconium Stained Amniotic Fluid: A Randomized Controlled Trial

Chettri

Adhisivam

Bhat

2015

The Journal of Pediatrics

105

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Section: Discussionmentioning

confidence: 63%

Endotracheal Suction for Nonvigorous Neonates Born through Meconium Stained Amniotic Fluid: A Randomized Controlled Trial

Chettri

Adhisivam

Bhat

2015

The Journal of Pediatrics

105

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“…The dpsA gene plays an important role during growth in amniotic fluid. S. agalactiae is known to infect the placenta and grow in amniotic fluid to high cell densities (15,50,66). The importance of peptide uptake for growth of S. agalactiae in amniotic fluid was studied with the strain O90R and the triple mutant ⌬dppB ⌬oppB ⌬dpsA.…”

Section: Resultsmentioning

confidence: 99%

Relevance of Peptide Uptake Systems to the Physiology and Virulence of Streptococcus agalactiae

et al. 2004

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Streptococcus agalactiae is a major cause of invasive infections in human newborns. To satisfy its growth requirements, S. agalactiae takes up 9 of the 20 proteinogenic amino acids from the environment. Defined S. agalactiae mutants in one or several of four putative peptide permease systems were constructed and tested for peptide uptake, growth in various media, and expression of virulence traits. Oligopeptide uptake by S. agalactiae was shown to be mediated by the ABC transporter OppA1-F, which possesses two substrate-binding proteins (OppA1 and OppA2) with overlapping substrate specificities. Dipeptides were found to be taken up in parallel by the oligopeptide permease OppA1-F, by the dipeptide ABC transporter DppA-E, and by the dipeptide symporter DpsA. Reverse transcription-PCR analysis revealed a polycistronic organization of the genes oppA1-F and dppA-E and a monocistronic organization of dpsA in S. agalactiae. The results of quantitative real-time PCR revealed a medium-dependent expression of the operons dppA-E and oppA1-F in S. agalactiae. Growth of S. agalactiae in human amniotic fluid was shown to require an intact dpsA gene, indicating an important role of DpsA during the infection of the amniotic cavity by S. agalactiae. Deletion of the oppB gene reduced the adherence of S. agalactiae to epithelial cells by 26%, impaired its adherence to fibrinogen and fibronectin by 42 and 33%, respectively, and caused a 35% reduction in expression of the fbsA gene, which encodes a fibrinogen-binding protein in S. agalactiae. These data indicate that the oligopeptide permease is involved in modulating virulence traits and virulence gene expression in S. agalactiae.Streptococcus agalactiae has a limited capacity to synthesize amino acids and must acquire from the environment 9 of the 20 proteinogenic amino acids for growth (38). The amino acid requirements of S. agalactiae can be satisfied by the uptake of peptides, which are cleaved in the cytoplasm to their respective amino acids (69, 70). In microorganisms, two different peptide uptake systems have been described (23, 41). The most common peptide transporters are binding-protein-dependent permeases, consisting of multiple components, belonging to the ATP-binding cassette (ABC) transporter superfamily (24). The process of peptide transport by ABC transporters involves the extracytoplasmic binding of the substrate by a substrate-binding protein, transfer of the substrate to two membrane-integrated permeases for translocation across the cytoplasmic membrane, and ATP hydrolysis by one or two proteins located on the cytoplasmic side of the membrane (24). In numerous bacteria, the uptake of di-and oligopeptides is mediated by these ABC transporters (41). In contrast, some microorganisms take up diand/or tripeptides by single proteins with similarity to eukaryotic peptide transport proteins of the PRT family (62). These bacterial permeases use the proton motive force across the cytoplasmic membrane for the uptake of peptides (23, 37). They exhibit a broad substrate spec...

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“…While exact in vivo bacterial growth environments are difficult if not impossible to duplicate in vitro, certain host niches can support rapid GBS growth. For example, GBS proliferation in human amniotic fluid in vitro was previously shown to be rapid (6), with a calculated cell generation time of 16 min during exponential growth. A t d of 0.8 h has been achieved by GBS in continuous culture with a chemically defined medium (30), and potentially faster t d s are theoretically achievable with complex media.…”

Section: Vol 75 2007 Transcriptional and Proteomic Profiles Of Gbs mentioning

confidence: 99%

Transcriptional and Proteomic Profiles of Group B Streptococcus Type V Reveal Potential Adherence Proteins Associated with High-Level Invasion

et al. 2007

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Group B Streptococcus (GBS) is an opportunistic organism that can harmlessly colonize the human gut, vagina, and rectum but can also cause pneumonia, sepsis, and meningitis in neonates born to colonized mothers. We have shown previously that growth rate and oxygen level regulate the ability of GBS to invade eukaryotic cells in vitro. Herein we extend and expand on these observations to show that GBS type V, an emergent serotype, grown in a chemostat at a cell mass-doubling time (t d ) of 1.8 h with oxygen invaded human ME-180 cervical epithelial cells in large numbers compared with those grown at the same t d without oxygen or at a slower t d of 11.0 h. The fact that several GBS type V cell wall-associated and membrane proteins were expressed exclusively under the invasive growth condition prompted an investigation, using genomics and proteomics, of all upregulated genes and proteins. Several proteins with potential roles in adherence were identified, including an undefined surface antigen (SAG1350), a lipoprotein (SAG0971), penicillin-binding protein 2b (SAG0765), glyceraldehyde-3-phosphate dehydrogenase (SAG0823), and an iron-binding protein (SAG1007). Mouse antisera to these five proteins inhibited binding of GBS type V to ME-180 cells by >85%. Recombinant undefined surface antigen (SAG1350), lipoprotein (SAG0971), and penicillin-binding protein 2b (SAG0765) each bound to ME-180 cells in a dose-dependent fashion, confirming their ability to act as ligands.Collectively, these data increase the number of potential GBS adherence factors and also suggest a role for these surface-associated proteins in initial pathogenic events.Group B Streptococcus (GBS) is a facultative anaerobe that can persist in both poorly and well-oxygenated tissues in humans. It commonly colonizes the anaerobic environments of the rectum and the vagina but can also colonize, grow, and disseminate from the oxygen-rich lungs of a newborn and cause pneumonia, life-threatening sepsis, and meningitis. That the presence of oxygen during growth is positively associated with the ability of GBS to invade human cells was recently demonstrated in vitro with GBS grown in a chemostat, where nutrient conditions are precisely controlled (17). In addition to oxygen, the rate of growth also influences invasiveness, as shown by the fact that GBS grown in a chemostat at a cell mass-doubling time (t d ) of 1.8 h invaded respiratory epithelial cells in significantly greater numbers than did those grown at a relatively slower t d of 11.0 h (25).Newly described genes such as those encoding the penicillinbinding protein (PBP) (ponA) (19), superoxide dismutase (sodA) (33), the delta subunit of RNA polymerase (18), glutamine transporter (glnQ) (40), and RogB, a transcriptional regulator of GBS (12), add to a growing list of GBS virulence factors. Indeed, the sequencing of GBS genomes from several serotypes (41), including types V and III (8, 42), and technologies such as DNA microarray and proteomic analysis now allow global approaches to revealing the complex natu...

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The Effect of Meconium Staining of Amniotic Fluid on the Growth of Escherichia coli and Group B Streptococcus

Cited by 37 publications

References 25 publications

Endotracheal Suction for Nonvigorous Neonates Born through Meconium Stained Amniotic Fluid: A Randomized Controlled Trial

Endotracheal Suction for Nonvigorous Neonates Born through Meconium Stained Amniotic Fluid: A Randomized Controlled Trial

Relevance of Peptide Uptake Systems to the Physiology and Virulence of Streptococcus agalactiae

Transcriptional and Proteomic Profiles of Group B Streptococcus Type V Reveal Potential Adherence Proteins Associated with High-Level Invasion

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