18 research outputs found
Recommended from our members
The essential genome of Streptococcus agalactiae.
BACKGROUND: Next-generation sequencing of transposon-genome junctions from a saturated bacterial mutant library (Tn-seq) is a powerful tool that permits genome-wide determination of the contribution of genes to fitness of the organism under a wide range of experimental conditions. We report development, testing, and results from a Tn-seq system for use in Streptococcus agalactiae (group B Streptococcus; GBS), an important cause of neonatal sepsis. METHODS: Our method uses a Himar1 mini-transposon that inserts at genomic TA dinucleotide sites, delivered to GBS on a temperature-sensitive plasmid that is subsequently cured from the bacterial population. In order to establish the GBS essential genome, we performed Tn-seq on DNA collected from three independent mutant libraries-with at least 135,000 mutants per library-at serial 24 h time points after outgrowth in rich media. RESULTS: After statistical analysis of transposon insertion density and distribution, we identified 13.5 % of genes as essential and 1.2 % as critical, with high levels of reproducibility. Essential and critical genes are enriched for fundamental cellular housekeeping functions, such as acyl-tRNA biosynthesis, nucleotide metabolism, and glycolysis. We further validated our system by comparing fitness assignments of homologous genes in GBS and a close bacterial relative, Streptococcus pyogenes, which demonstrated 93 % concordance. Finally, we used our fitness assignments to identify signal transduction pathway components predicted to be essential or critical in GBS. CONCLUSIONS: We believe that our baseline fitness assignments will be a valuable tool for GBS researchers and that our system has the potential to reveal key pathogenesis gene networks and potential therapeutic/preventative targets.This work was supported by NIH/NIAID R01 AI092743, R33 AI098654, and R21 AI11020 to A.J.R.; NIH/NICHD K23 HD065844 to T.M.R.; John M. Driscoll, Jr., M.D. Children’s Fund (Columbia University Department of Pediatrics) and the Pediatric Scientist Development Program (NIH/NICHD K12 HD000850) to T.A.H
Normal flora and bacterial vaginosis in pregnancy: an overview
The female genital tract is an intricate, yet balanced ecosystem that hosts a variety of
different residential microflora. The physiological changes that occur during pregnancy may
disrupt this balanced ecosystem and predispose women to a potentially pathogenic
microbiota. Bacteria that are associated with bacterial vaginosis (BV) are opportunistic
pathogens that frequently form part of this microbiota. The overgrowth of and infections
with these bacteria are linked to poor obstetric outcomes and increased transmission of other
reproductive tract infections (RTIs). These infections increase women’s susceptibility of
acquiring HIV, the rates of HIV shedding and the development of Acquired Immune Deficiency Syndrome (AIDS) in HIV infected patients. It is unknown how the plethora of
bacterial species associated with BV contributes to the dynamics of this condition. The use
of high-throughput methods have led to the in-depth investigation of different BV-related
bacterial species and the functional capabilities of these species. However, the pathogenesis
of BV is still poorly defined and the role of individual BV-related bacterial species in specific
pregnancy complications is unclear and controversial. The majority of BV infections are
asymptomatic and successful diagnosis is complicated by the lack of reliable and
standardized diagnostic tests.University of Pretoria, the Medical Research Council
(South Africa) and the National Health Laboratory Service (NHLS).http://www.tandfonline.com/loi/imby202017-05-31hb2016Medical Microbiolog