Pyelonephritis (Kidney Infection) and Perinephric Abscess: Diagnosis & Management

by John Fisher, MD

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    00:01 In the laboratory, we look for the presence of pyuria and 10 white cells per microlitre of mid-stream urine in a counting chamber is the gold standard.

    00:15 However, a counting chamber is not available that often.

    00:20 So we can use just centrifuged urine and look for 5 to 10 white cells per high power microscopic field.

    00:30 We also had the dipstick leukocyte esterase test.

    00:34 Leukocyte esterase is present in the granules of neutrophils.

    00:38 So if the leukocyte esterase is positive, then by inference, you can say there are white cells in the urine.

    00:45 And the sensitivity and specifity are decent -- 75-96% sensitive, 94-98% specific.

    00:55 Once again, if a patient does not have microscopic hematuria it's probably not coming from the urinary tract.

    01:02 The source of the fever is somewhere else.

    01:07 The urine culture in pylonephritis certainly should have a least 10 to the 5th bacteria per mL.

    01:14 And a poor man's culture is to look under the microscope looking for microorganisms.

    01:22 You can do it by Gram stain.

    01:23 If you see 1 organism per microscopic field, you can basically conclude that there are at least 10 to the 5th organisms per mL of that infected urine.

    01:39 When do we need to image people? Well, for uncomplicated pylonephritis, when the diagnosis is clear, the patient's moderately ill, we don't need to image them.

    01:51 We need to image them for complicated pylonephritis, when we suspect a structural urologic abnormality, when we're not sure what's going on and urinary tract infection pylonephritis is up high on the list, if someone obviously is unusually, severely ill with symptoms of urinary tract infection and it would be prudent in an immuno-compromised patient to get imaging because they may have not only urologic abnormalities but they may have serious abscess in the kidney or other organs in the abdomen.

    02:29 Then obviously patients who fail to improve from the choice of therapy we give them for pylonephritis.

    02:37 or for males who have suffered recurrent infections.

    02:44 What's the sequence of imaging? we start looking with a plain film and what we're looking for are calculi, stones because that can be a reason for either the first time or recurrent pylonephritis and also we can detect some soft tissue masses.

    03:01 Renal ultrasound is the next step, and a renal ultrasound can tell you not only the presence of pylonephritis but perinephric abscess.

    03:10 And if it's necessary, a CT scan can show you intrarenal or perinephric abscess.

    03:16 I think you can see the intrarenal abscess on this particular projection.

    03:23 So how do we treat uncomplicated pylonephritis? Well, we need to choose any microbials that have good activity against the offending pathogen and you will have a urine culture hopefully to go by.

    03:38 So if Gram-negative bacteria are seen on a urine smear, we'd assume E. coli.

    03:45 And since it's a serious illness, we're probably going to choose a fluoroquinolone, ciprofloxacin or levofloxacin for 5-7 days.

    03:54 We wouldn't give that to children, remember, because of the adverse consequences of quinolones on soft tissue like tendons.

    04:05 TMP/SMX for 14 days or plus or minus 1 dose of ceftriaxone or aminoglycoside is often given.

    04:17 Gram-positive cocci seen in chains on urine smear or known in culture would get amoxicillin, 'cause we'd be thinking of the Enterococcus.

    04:28 And like I mentioned, if you see Gram-positive cocci in clusters or Staph aureus is growing -- I'd like to pause here and those of you who have seen patients probably say "Isn't that funny that the patient would grow Staph especially Staph aureus in the urine? That's not a urinary tract pathogen.

    04:53 What's that doing there?" That's exactly the question I want all good physicians to ask because that Staph aureus may have gotten there from the bloodstream.

    05:07 In other words, the patient may have infective endocarditis, a heart valve infection, that then got into the blood stream and seeded the kidneys producing a pylonephritis.

    05:20 So the pylonephritis came from some other source of staphylococcal bacteremia.

    05:26 So if you have a patient with Staph aureus that you think is causing the urinary tract infection, draw blood cultures and work the patient up for a serious staphylococcal infection elsewhere.

    05:39 That's an important thing to think about.

    05:42 But if you indeed had Staph aureus, then you would consider, "Is this methicillin-resistant staph?" And you would consider linezolid or TMP/SMX for 14 days.

    05:58 Obviously, since it's an uncomplicated infection, you would't necessarily need to hospitalize and give them vancomycin for that length of time.

    06:09 You can also start with parenteral therapy in patients who are quite ill.

    06:15 And so for those who have Gram-negative rods causing the problem, fluoroquinolones for 7 days or extended-spectrum beta-lactam for 14 days.

    06:28 For gram-positive cocci clusters its Ampicillin for 14 days.

    06:35 For gram-positive cocci clusters as we talked about now we would have to think about vancomycin for 14 days.

    06:45 Now as far as the surgical management goes, what we need to do is we need to, first of all, identify whether there is anything to drain.

    06:55 And we can do that with either ultrasound or CT, and we can use both of those tools to identify abscesses and drain them.

    07:05 And there's about 90% success rate with doing just that.

    07:09 For complicated pyelonephritis you need to do imaging studies of the kidneys, like CT, to determine the extent of pathology.

    07:17 If there is a perinephric abscess, this should be drained.

    07:20 If there is an obstruction, this should be relieved either by cystoscopy or with other urologic measures.

    07:26 Is is very important to carefully select the parenteral antibiotics based on culture and sensitivity.

    About the Lecture

    The lecture Pyelonephritis (Kidney Infection) and Perinephric Abscess: Diagnosis & Management by John Fisher, MD is from the course Urinary Tract Infections. It contains the following chapters:

    • Pyelonephritis and Perinephric Abscess – Diagnosis
    • Uncomplicated Infection – Management

    Included Quiz Questions

    1. Presence of white blood cells in the urine
    2. Lower urinary tract infection
    3. Pyelonephritis
    4. Presence of urinary stones
    5. Glomerulonephritis
    1. Failure to improve with antibiotic therapy
    2. Acute uncomplicated urinary tract infection
    3. Acute pyelonephritis
    4. Recurrent cystitis in a sexually active woman
    5. Pregnancy
    1. 75%
    2. 35%
    3. 50%
    4. 65%
    5. 20%
    1. Ultrasound
    2. Abdominal X-ray
    3. Computed tomography scan
    4. Magnetic resonance imaging
    5. Voiding cystourethrography

    Author of lecture Pyelonephritis (Kidney Infection) and Perinephric Abscess: Diagnosis & Management

     John Fisher, MD

    John Fisher, MD

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    By kate H. on 27. June 2017 for Pyelonephritis (Kidney Infection) and Perinephric Abscess: Diagnosis & Management

    concise, really easy to listen to. Gave salient points very well. Loved the pause for thought on the red flag of having a staph aureus urinary tract infection.