Comparison of virulence variations on MDCK monolayers by Escherichia coli isolated from acute lobar nephronia and acute pyelonephritis.

Escherichia coli is the most common pathogen associated with acute lobar nephronia (ALN), a clinically more severe parenchymal inflammatory disease that requires a longer duration of antibiotic treatment than acute pyelonephritis (APN). This study was conducted to unravel the virulence differences between clinical isolates of E. coli from pediatric ALN and APN patients. A total of 88 urinary isolates of E. coli were investigated. They were identified from radiologically diagnosed ALN and APN patients and had previously been molecularly characterized for important urovirulence genes. Madin-Darby canine kidney (MDCK) epithelial cells were used as an in vitro model. Multivariate logistic regression analyses indicated that ALN isolates were more likely to show adhesion (p<0.05; odds ratio [OR], 3.81; 95% confidence interval [CI], 1.23-11.80) and cytotoxicity (p<0.001; OR, 10.42; 95% CI, 3.03-35.89). However, no difference in the penetration ability was noted. Henceforth, the ability to adhere to and produce cytotoxicity against uroepithelial cells appears a prerequisite factor for E. coli to cause more severe bacterial kidney infection, such as ALN.