Enhancing a multipurpose artificial urine for culture and gene expression studies of uropathogenic Escherichia coli strains

Uropathogenic Escherichia coli (UPEC) are the most common cause of urinary tract infections, which pose a great burden on global health and the economy through morbidity, mortality, healthcare costs and loss of productivity. Pooled human urine can be used as a growth medium for in vitro studies, however even if the same donors are used, composition can vary depending largely on diet and fluid intake. There have been a number of artificial urine formulae used as alternatives to pooled human urine. However, we observed that a recently reported multipurpose artificial urine was unable to support the growth of prototypic UPEC strains suggesting it lacked key metabolites. We therefore used liquid chromatography mass spectrometry to identify and adjust the metabolic profile of multipurpose artificial urine closer to that of pooled human urine. Modification in this way facilitated growth of UPEC strains with growth rates similar to those obtained in pooled human urine. Transcriptomic analysis of UPEC strains cultured in enhanced artificial urine and pooled human urine showed that the gene expression profiles are similar, with less than 7% of genes differentially expressed between the two conditions. The data support this enhanced artificial urine as a robust media to study aspects of UPEC physiology in vitro.