Bacteriuria: the presence of bacteria in the urine

1
Introduction

• Bacteriuria the presence of bacteria in the
  urine
• Significant bacteriuria 105 organism or more per
  milliliter
• Pyuria the presence of white blood cells in
  urine
• Pyuria with 5 or more cells per microscopic
• high-power field reliable indicator of UTI
• The absence of such pyuria does not reliably
• exclude UTI

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Acute Pyelonephritis (1)

• The most and second commonest (90) of
  community-acquired UTIs in females are due to E.
  coli and Staphylococcus saprophyticus. Other
• enterobacteria (Proteus spp., Klebsiella
  spp.,
• Enterobacter spp.) are also encountered.
• In male patients E. coli is also the commonest
• pathogen, but other enterobacteria and
• Enterococcus spp. are more commonly
• encountered.

3
Acute Pyelonephritis (2)

• In hospital, E. coli is still common, but a high
• frequency of Pseudomonas spp., Enterococcus
• spp., coagulase-negative staphylococci and
• Candida spp. is encountered.
• Persistent or relapsing bacteriuria due to
  Proteus
• mirabilis should search for staghorn
  calculus.
• Patients with Staphylococcus aureus in urine
• culture should be search for intravascular
  cannula infections, endocarditis, osteomyelitis
  and pneumonia.

4
Acute Pyelonephritis (3)

• APN is a syndrome of fever along with evidence of
  renal inflammation such as costovertebral angle
  tenderness or flank pain.
• Silent pyelonephritis is present in up to 30 to
  50 of patients with clinical cystitis in primary
  care setting.
• Deterioration of condition should prompt a
  search for urinary tract obstruction such as
  calculus or renal papillary necrosis, or for a
  suppurative focus in or around the kidney.

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Acute Pyelonephritis (4)

• Ultrasound is the initial investigation for
  patients with upper urinary tract infection and
  suspected obstruction. Ultrasound and KUB will
  detect almost all correctable lesions.
• CT is indicated is a patient with persistent
  sepsis in whom ultrasound does not reveal an
  explanation.
• IVU has a limited role. It is effective at
  excluding obstruction.
• Retrograde urography with cystoscope will
  demonstrate the anatomy of the collecting system
  in a nonexcreting kidney.

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Acute Pyelonephritis (5)

• Aminoglycoside combined with ampicillin,
  cefazolin, or TMP-SMX is appropriate as empiric
  therapy of APN.
• Aminoglycoside combined with ureidopenicillin
  such as piperacillin may be preferred for
  hospital-acquired infection, where P. aeruginosa
  and E. fecalis are more likely to be encountered.
• E. coli isolates from community-acquired
  infection 30 are resistant to ampicillin, 10
  to first-generation cephalosporins and TMP-SMX,
  less than 2 to aminoglycoside.

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Acute Pyelonephritis (6)

• Approximately 40 of nosocomial aerobic
  gram-negative urinary isolates are resistant to
  first-generation cephalosporins.
• In patients with a higher risk of aminoglycoside
  toxicity such as those with prior renal
  impairment, liver dysfunction,advanced age,
  shock, or oliguria, third-generation
  cephalosporins such as cefotaxime, ceftriaxone,
  ceftizoxime or ceftazidime monobactam such as
  aztreonam carbapenem such as imipenem
  ureidopenicillin such as piperacillin,
  ticarcillin, or parenteral quinolone such as
  ciprofloxacin should be considered.

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Acute Focal Bacterial Nephritis (1)

• Human kidneys consist of five to eleven lobes
  each of which contains a conical medullary
  pyramid. Each pyramid is capped by cortical
  tissue to from a renal lobe.
• AFBN infection limited to one or more renal
  lobes.
• CT with contrast enhancement may reveal one or
  more wedge-shaped areas of decreased density.
• IVU is usually normal. Ultrasound may be normal
  or reveal a solid, hypoechoic , poorly defined
  mass without evidence of liquefaction.

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Acute Focal Bacterial Nephritis (2)

• Histopathology shows intense PMN infiltration
  without liquefaction, so needle aspiration or
  percutaneous drainage is not indicated.
• E. coli is the most common organism isolated from
  patients with AFBN.
• Antimicrobial therapy as APN.

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Renal Abscess (1)

• Renal abscess may be due to AFBN progression to
  suppuration when associated with obstruction,
  ascending infection, or hematogenous spread.
• The usual pathogens are enterobacteria and S.
  aureus (preantibiotic era, history of cutaneous
  staphylococcal infection such as furuncle).
• Clinical presentations fever and chills along
  with back or abdominal pain, CVA tenderness,
  flank mass, guarding of the upper lumbar and
  paraspinal muscles.

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Renal Abscess (2)

• IVU is abnormal (mass effect) but nonspecific.
• Ultrasound shows an ovoid mass of decrease
  attenuation within the parenchyma.
• CT shows a marginated low attenuation (0-20 HU)
  mass that fails to enhance. There may be a
  surrounding rim of increased enhancement (the
  ring sign).
• The diagnosis can be confirmed by gallium scan,
  WBC scan, or needle aspiration.

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Renal Abscess (3)

• TREATMENT
• 1. Intravenous antimicrobial therapy
• 2. Percutaneous drainage (ultrasound
• or CT guidance)
• 3. Incision and drainage
• 4. Nephrectomy

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Emphysematous Pyelonephritis and Pyocystis (1)

• Gas within the urinary tract has three origins
• 1. Atmospheric gas introduced during
• diagnostic procedures or during trauma.
• 2. As a result of a fistula with a hollow
  organ.
• 3. From multiplying, gas-producing organism
• such as enterobacteria or anaerobes.
• Emphysematous pyelonephritis is a disease
• characteristic by gas formation in the renal
• parenchyma and surrounding tissues.

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Emphysematous Pyelonephritis and Pyocystis (2)

• Fulminant disease with high mortality.
• The majority of patients have uncontrolled DM and
  obstruction of the urinary tract.
• E. coli and other enterobacteria account for the
  majority of pathogens with the rest being
  polymicrobial anaerobes.
• DDx 1. Gas in renal tumor, which can occur after
  embolization. 2. Evolving traumatic renal
  infarct.

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Emphysematous Pyelonephritis and Pyocystis (3)

• KUB diffuse mottling of the parenchyma (early
  sign), extensive bubbles in the parenchyma and a
  gas crescent surrounding the kidney within the
  perinephric space (advanced cases).
• Ultrasound dirty shadowing with poorly defined
  margins. (clean shadowing with sharply defined
  margins in calculi).
• CT identify gas clearly.

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Emphysematous Pyelonephritis and Pyocystis (4)

• Surgical intervention within 48 h combined with
  antimicrobial therapy has improved outcome.
• Pyocystis (pus in the urinary bladder) can
  present with features of sepsis, lower urinary
  tract signs, and pneumaturia.
• Antimicrobial therapy and bladder irrigation may
  be sufficient therapy, but necrosis of the
  bladder wall (gas in the muscular layers on CT)
  will require surgical resection.

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Perinephric Abscess (1)

• The perinephric space contains the kidney, the
  renal fat, and the adrenal gland.
• Perinephric abscess generally arises from an
  intrarenal abscess.
• The majority are due to enterobacteria and a
  minority to S. aureus. Polymicrobial aerobic and
  anaerobic bacteria are also common.
• Documentation of anaerobic cause should search
  for either GI tract source or ureteric
  obstruction.

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Perinephric Abscess (2)

• Perinephric abscess is an insidious disease that
  has a 50 mortality due to delay in diagnosis.
• Clinical presentations fever and chills (most
  common), weight loss, nausea, vomiting, dysuria,
  flank or abdominal pain, pleuritic chest pain,
  flank mass, renal tenderness, and pain in the
  thigh or groin (psoas abscess).
• Ultrasound fluid that may contain debris or gas.
• CT loculated fluid collection with decrease
  attenuation (0-20 HU).

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Perinephric Abscess (3)

• The diagnosis and be confirmed by aspiration of
  the pus with a 20-gauge needle.
• Most patients can be treated by a combination of
  intravenous antimicrobial agents and percutaneous
  drainage.
• Clindamycin combined with either an
  aminoglycoside or a 3rd-generation cephalosporin
  is appropriate as initial empiric therapy if
  abscess due to polymicrobial aerobic and
  anaerobic or S. aureus organisms are suspected.

21
Pyonephrosis (1)

• Pyonephrosis arises when infection develops
  proximal to an obstruction of a hydronephrotic
  kidney.
• Underlying causes calculus, stricture, neoplasm,
  or congenital anomaly.
• Loss of renal function is often present.
  Intrarenal or perinephric abscess may also be
  present.
• Clinical features similar to perinephric
  abscess.
• KUB look for calculi.

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Pyonephrosis (2)

• Ultrasound distended upper urinary tract,
  sedimented echoes, and internal echoes within the
  dilated collecting system.
• CT sensitive for detecting radiolucent calculi.
• Treatment intravenous antimicrobial agent with
  percutaneous drainage with nephrostomy tube, and
  correct the underlying disease.

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UTI due to Candida (1)

• Candida species are normal GI tract commensals of
  humans whose number are usually suppressed by the
  bacteria flora.
• Primary infection of the urinary tract is
  generally associated with prolonged placement of
  a urinary catheter along with antibacterial
  agent.
• Disseminated candidiasis may originate in the
  urinary tract or secondarily seed it.
• Candida in urine culture with 104 cfu/ml bladder
  infection, and associated with renal infection.

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UTI due to Candida (2)

• Renal infection requires systemic amphotericin B
  therapy in a dose of 0.6 mg/(kg.day)
• Fluconazole and 5-fluorocytosine are alternative,
  less reliable therapies.
• Ketoconazole is not acceptable as it is not
  excreted through the kidney.
• Hydronephrosis due to fungus ball PCN with
  amphotericin B irrigation. Lack of response
  should prompt surgical excision.

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UTI due to Candida (3)

• A more commonly encountered situation is that of
  the stable ICU patient who has persistent
  candiduria.
• For such a patient amphotericin B bladder
  irrigation (50 mg in 1000mL of sterile water
  administered over 24 h by three war catheter) for
  5 days should be considered.

27
Prostatic Infections (1)

• Acute bacterial prostatitis (ABP) may present
  with the sudden onset of high fever up to 40C,
  chills and malaise which are soon followed by
  irritative symptoms such as urgency, frequency,
  dysuria.
• Other clinical presentations dull, aching pain
  in the perineum, rectum, or sacrococcygeal
  region difficulty voiding or acute urinary
  retention.
• Digital rectal examination reveals a very tender,
  swollen, and warm prostate.

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Prostatic Infections (2)

• Gram-negative enteric organisms are now the most
  frequent pathogens. Enterococcus fecalis may also
  be responsible.
• Treatment regimen for ABP similar to treatment
  of APN.
• If the patient responds appropriately, the
  parenteral antimicrobial therapy can be continued
  for 7 days, then oral antimicrobial agent such as
  TMP-SMX, norfloxacin, or ciprofloxacin for
  further 5 weeks.

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Catheter-Associated Bacteriuria

• One percent of patients will acquire bacteriuria
  from single in-out catheterization.
• The per day risk of developing bacteriuria is
  about 5 thus about 40 of patients catheterized
  for 10 days will have acquired significant
  bacteriuria.
• Asymptomatic bacteriuria should be treated in all
  patients prior to instrumentation to avoid the
  development of gram-negative bacteremia and
  subsequent sepsis.