[Bacteriology of urinary germs responsible of pyelonephritis]

Cytobacteriological examination of urine is indispensable in patients with acute or chronic pyelonephritis. Direct examination through the microscope is fundamental in acute pyelonephritis where immediate antibiotic therapy is mandatory. A significant bacteriuria points to an obstacle to urine flow. Escherichia coli is the most common pathogen in acute and chronic pyelonephritis. Isolating a Proteux strain suggests that lithiasis is present. Pseudomonas aeruginosa always has a nosocomial origin and is often responsible for chronic asymptomatic pyelonephritis. Staphylococci and enterococci may produce pyelonephritis, notably when it is associated with urinary stones. Since hospital- or community-acquired strains of E. Coli are strongly resistant to aminopenicillins and cotrimoxazole, these antibacterials must not be used as first-line treatment of pyelonephritis.