Host and bacterial virulence factors predisposing to emphysematous pyelonephritis.
BACKGROUND
Emphysematous pyelonephritis (EPN) is a rare, severe, gas-forming infection of the kidney, and its precise pathogenesis remains obscure.


METHODS
To investigate the roles of host and bacterial virulence factors in the pathogenesis of EPN, we compared: (1) host factors in patients with EPN (n = 47) with those in patients with acute renal infections without gas formation (non-EPN; n = 79), (2) the prevalence of virulence gene in causative Escherichia coli strains from 16 of the 47 EPN cases with all 79 non-EPN cases by means of polymerase chain reaction analysis, and (3) gas volumes produced by EPN and non-EPN strains cultured in broths at 3 glucose concentrations (100, 180, and 250 mg/dL [5.6, 10.0, and 13.9 mmol/L]).


RESULTS
Diabetes mellitus (DM) with poor glycemic control (ie, hemoglobin A1c level > 11%) and urinary tract obstruction were more prevalent in the EPN group. However, DM with poor glycemic control was the only host factor independently associated with EPN (odds ratio, 4.9; P = 0.018). EPN strains had a greater prevalence of the uropathogenic-specific protein (usp) genes. Multivariate analyses also showed the association between usp and EPN with borderline significance (odds ratio, 8.4; P = 0.057). There was no significant difference in gas production by E coli isolated from patients with or without EPN.


CONCLUSIONS
DM with poor glycemic control and urinary tract obstruction are host factors predisposing to EPN. There was no difference in gas production between EPN and non-EPN E coli strains. The distribution of E coli virulence genes was remarkably similar between the 2 groups. However, the PapG II adhesin (papG II) gene is significantly decreased and the usp gene is increased with borderline significance in EPN E coli strains.
Tseng
Chin-Chung
CC
Division of Nephrology, Department of Internal Medicine, National Cheng Kung University Hospital, Tainan, Taiwan.
Wu
Jiunn-Jong
JJ
Wang
Ming-Cheng
MC
Hor
Lien-I
LI
Ko
Yen-Hsiu
YH
Huang
Jeng-Jong
JJ
D000368:Aged; D001786:Blood Glucose / Q000032:analysis; D048909:Diabetes Complications / Q000453:epidemiology / Q000382:microbiology; D004198:Disease Susceptibility; D004646:Emphysema / Q000453:epidemiology* / Q000209:etiology / Q000382:microbiology; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000150:complications; D005260:Female; D005285:Fermentation; D005740:Gases; D005798:Genes, Bacterial; D005947:Glucose / Q000378:metabolism; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D016867:Immunocompromised Host; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011704:Pyelonephritis / Q000453:epidemiology* / Q000209:etiology / Q000382:microbiology; D012307:Risk Factors; D014570:Urologic Diseases / Q000150:complications; D014774:Virulence / Q000235:genetics
D001786:Blood Glucose; D005740:Gases; D005947:Glucose; D006442:Glycated Hemoglobin