What is the etiology of acute pyelonephritis (kidney infection)?

Updated: Jul 01, 2021
  • Author: Tibor Fulop, MD, PhD, FACP, FASN; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Answer

Uropathogens that cause the majority of acute pyelonephritis cases and the frequency with which they are cultured in uncomplicated versus complicated cases, are listed in Table 1. Unusual pathogens include mycobacteria, yeasts and fungi, and opportunistic pathogens such as Corynebacterium urealyticum.

 

Table 1. Bacterial Etiology of Urinary Tract Infections (Open Table in a new window)

Bacteria

% Uncomplicated

% Complicated

Gram negative

 

 

Escherichia coli

70-95

21-54

Proteus mirabilis

1-2

1-10

Klebsiella spp

1-2

2-17

Citrobacter spp

< 1

5

Enterobacter spp

< 1

2-10

Pseudomonas aeruginosa

< 1

2-19

Other

< 1

6-20

Gram positive

 

 

Coagulase-negative staphylococci

5-10*

1-4

Enterococci

1-2

1-23

Group B streptococci

< 1

1-4

Staphylococcus aureus

< 1

1-23

Other

< 1

2

Adapted from Hooton TM. The current management strategies for community-acquired urinary tract infection. Infect Dis Clin North Am. Jun 2003;17(2):303-32. [Medline].

* S saprophyticus


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