A boy is suffering from acute pyelonephritis. Most specific urinary finding will be
Ans. is 'a' i.e. W.B.C. casts RememberThey have specifically asked about pyelonephritis, not urinary tract infection. There are three basic forms of urinary tract infectionPyelonephritisCystitisAsymptomatic bacteriuriapyelonephritisUrinary tract infection involving the renal parenchyma, if there is no parenchymal involvement, the condition may be termed pyelitis.cystitisIt indicates bladder involvement.asymptomatic bacteriuriaIt refers to individuals who have a positive urine culture without any manifestation of infection and occur almost exclusively in girls. Remember that casts can only be formed in the kidney. The presence of cast is specific for kidney. Casts cannot be formed from anywhere else in the urinary tractCasts are the only elements found in urinary sediments which are unique to the kidney.Thus whenever WBC casts are present in a patient suspected of having urinary tract infection it confirms pyelonephritis.According to Harrison "leucocyte casts can be detected in urine of only selected patients but the detection of these casts is pathognomic"About "Bacteria in gram stain"Bacteria in gram stain can be positive in any type of urinary tract infection whether it is pyelonephritis, cystitis, or urethritis.Presence of bacteria confirms the urinary tract infection but the exact site is detected by W.B.C. casts.Still of am not sure of the answer, because on page 251 Harrison states "The presence of bacteria suggests infection and white blood cell casts with bacteria are indicative of pyelonephritis. White blood cells and or white blood cell casts may also be seen in tubulointerstitial processes such as interstitial nephritis, S.L.E and transplant rejection"Nitrite testMore than 90% of common urinary pathogen (gram negative rods) are nitrite producing bacteria.In the presence of infection urinary nitrate is converted to nitrite which can be detected in urine.A positive nitrite test indicates infection with nitrite producing bacteria.Leucocyte esterase testA positive test is seen in presence of WBC's in urine and suggestive of pyuria.A positive leucocyte esterase test results from the presence of WBC. A negative leucocyte esterase test indicates that an infection is unlikely and that without additional evidence of urinary tract infection urine culture need not be.Once again, make it clear"Although white cell casts may be observed in other conditions they are along with other features of UT1 specific for acute pyelonephritis "'
W.B.C. casts
Leucocyte esterase test
Nitrite test
Bacteria in gram stain
Urinary Tract Infections and Interstitial Cystitis