Difference in the Metabolome between Escherichia Coli Isolated from Patients with Pyelonephritis and Cholangitis

Abstract

Escherichia coli can lead to invasive infection including pyelonephritis and cholangitis. We postulate that there are differences between E. coli strains causing these different clinical syndromes. Using mass spectrometry, we have analyzed the metabolome profile of 11 blood culture E. coli isolates from patients with pyelonephritis (Group P), 11 blood culture E. coli from patients with cholangitis (Group C), and 10 stool isolates from patients without pyelonephritis or cholangitis (Group S). We have successfully distinguished between different groups of E. coli using principal component analysis and hierarchical clustering. We have identified 378 biomarkers that were different between the three groups using reversed phase LC-MS positive mode, 475 biomarkers using reversed phase LC-MS negative mode, 145 biomarkers using normal phase LC-MS positive mode, and 68 biomarkers using normal phase LC-MS negative mode. Analysis using different modes is important because some markers may only be found in the analysis with a particular ionization mode. The criteria for a difference between the three different groups were a P value of <0.01 and a fold change of >16 between at least two groups. We have manually inspected all these biomarkers to exclude false positive biomarkers in statistical analysis. After preliminary analysis, we have identified 20 biomarkers which highly expressed in Group P. Further characterization of these potential biomarkers may shed light on the specific virulence factors, and also may be used in the differentiation of E. coli isolates arising from different sites, which will help the clinicians to manage the patients