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J Microbiol Methods

Title:		Evaluation of the in vitro growth of urinary tract infection-causing gram-negative and gram-positive bacteria in a proposed synthetic human urine (SHU) medium
Author(s):		Ipe DS; Ulett GC;
Address:		"School of Medical Science, and Menzies Health Institute Queensland, Griffith University, Gold Coast, QLD, 4222, Australia. School of Medical Science, and Menzies Health Institute Queensland, Griffith University, Gold Coast, QLD, 4222, Australia. Electronic address: g.ulett@griffith.edu.au"
Journal Title:		J Microbiol Methods
Year:		2016
Volume:		20160614
Issue:
Page Number:		164 - 171
DOI:		10.1016/j.mimet.2016.06.013
ISSN/ISBN:		1872-8359 (Electronic) 0167-7012 (Linking)
Abstract:		"Bacteriuria is a hallmark of urinary tract infection (UTI) and asymptomatic bacteriuria (ABU), which are among the most frequent infections in humans. A variety of gram-negative and gram-positive bacteria are associated with these infections but Escherichia coli contributes up to 80% of cases. Multiple bacterial species including E. coli can grow in human urine as a means to maintain colonization during infections. In vitro bacteriuria studies aimed at modeling microbial growth in urine have utilized various compositions of synthetic human urine (SHU) and a Composite SHU formulation was recently proposed. In this study, we sought to validate the recently proposed Composite SHU as a medium that supports the growth of several bacterial species that are known to grow in normal human urine and/or artificial urine. Comparative growth assays of gram-negative and gram-positive bacteria E. coli, Pseudomonas aeruginosa, Proteus mirabilis, Streptococcus agalactiae, Staphylococcus saprophyticus and Enterococcus faecalis were undertaken using viable bacterial count and optical density measurements over a 48h culture period. Three different SHU formulations were tested in various culture vessels, shaking conditions and volumes and showed that Composite SHU can support the robust growth of gram-negative bacteria but requires supplementation with 0.2% yeast extract to support the growth of gram-positive bacteria. Experiments are also presented that show an unexpected but major influence of P. mirabilis towards the ability to measure bacterial growth in generally accepted multiwell assays using absorbance readings, predicted to have a basis in the release of volatile organic compound(s) from P. mirabilis during growth in Composite SHU medium. This study represents an essential methodological validation of a more chemically defined type of synthetic urine that can be applied to study mechanisms of bacteriuria and we conclude will offer a useful in vitro model to investigate the basis of some of the most common infections of humans"
Keywords:		Amino Acids/pharmacology *Culture Media Escherichia coli/growth & development/isolation & purification Gram-Negative Bacteria/*growth & development/isolation & purification Gram-Negative Bacterial Infections/diagnosis Gram-Positive Bacteria/*growth & deve;
Notes:		"MedlineIpe, Deepak S Ulett, Glen C eng Evaluation Study Validation Study Netherlands 2016/06/18 J Microbiol Methods. 2016 Aug; 127:164-171. doi: 10.1016/j.mimet.2016.06.013. Epub 2016 Jun 14"