Lower urinary tract infectious disease

ICD10: Urinary tract infection, site not specified [N39.0]

Treatment: Empirical Abx; critical UTI & Pyelonephritis


Acute bacterial, viral or fungal infection of the urinary tract. E.coli is the most common organism in females' UTI, and staphylococcus saprophyticus is the second most common causative organism.

Men, elderly and pregnant women have a high risk of critical UTI and pyelonephritis.


In females, ascending infection from the vagina through the urethra is the most common; urinary incontinence increases the risk. Upper UTI can also be caused by hematological spread due to underlying morbidity; HIV, immunosuppressed, .

Men with BPH are at higher risk of UTI.


  1. Cystitis: dysuria, urinary frequency, urinary urgency, suprapubic pain, nocturia, pus-urine, and may associated with hematuria (rare).
  1. Pyelonephritis/systemic involvement: Cystitis picture + fever> 37.9 C or < 36 C (sign of severe sepsis) , back pain; costovertebral angle pain with tenderness, and nonspecific nausea/vomiting.

  2. Genital pruritus or discharge.

Factors of severity: 1. Infancy or elderly. 2. Anatomical malformation. 3. Iatrogenic foreign body. 4. Renal failure. 5. Chronic comorbidities. 6. T obstruction.


  1. Urinalysis: microscopically (WBC casts) + cytometry of > 10 WBC/mm^3.

  2. Dipstick: +ve for leukocyte esterase and nitrite (+ve in Enterobacteriaceae).

In the case of catheter in-place, take the sample from the catheter.

  1. Gram stain. (BEFORE: giving any antibiotics to avoid false negatives.)

  2. Urine culture; mid-stream clean catch; > 100 CFU/mL symptomatic UTI and >100000 CFU/mL for asymptomatic UTI. (BEFORE: giving any antibiotics to avoid false negatives.)

  3. Pelvic CT for upper UTI.

    • US or IV Urogram.
  4. WBC for leukocytosis.

  5. Blood culture. (BEFORE: giving any antibiotics to avoid false negatives.)

Risk factors:

  1. Females have a lifetime risk of 50%-60%.

  2. Active sexual life & history of recurrent UTI (multi-partners, think chlamydia or gonorrhea).

  3. Using spermicides, even in condoms.

  4. post-menopausal; risk of recurrent UTI, due to vaginal atrophy, incontinence.

  5. Iatrogenic; Foreign body or drug induce UTI.

  6. Immunocompromising co-morbidities; uncontrolled DM II, SCA, HIV, Iatrogenic.

  7. pregnancy; asymptomatic UTI (common), w/ high risk of pyelonephritis.

DDx: 1. Interstitial etiology.

  • Malignancy.
  • non-infectious.
  • painful bladder syndrome.
  • Urethral diverticulum.
  • Radiation-induced.

PMID: 31105774, 11237808, 15136308, EAU Guidelines, 15629728, 12020306, 9098661, 1580271,

Clinical Goal: 1. Bacterial eradication.

Targeted organisms:

Gram -ve: Escherichia coli (most common in females, and <50% in men), other Enterobacteriaceae; Klebsiella pneumonia (common in DM), and Proteus mirabilis, Providencia, Pseudomonas aeruginosa (common in Catheter-related UTI), and Acinetobacter.

Gram +ve: Staphylococcus saprophyticus, Enterococci

  1. Prevent sepsis.

Your choice of empirical antibiotics depends on your clinical judgment of causative organisms, local history of bacterial resistance, organs involvements, adverse effect profile, and cost/insurance coverage.

Management: Navigate between the lines of management based on isolated bacteria, patient's contraindications, history of local bacterial resistance, renal functions, AE tolerance, and cost/insurance coverage.

  1. Hospitalize if:

    • Inability to oral intake.
    • Elderly.
    • Vitally unstable.
    • High or low WBC.
    • Fever > 39 C.
    • Pregnancy.
    • immunocompromised.
  2. Oral fluoroquinolones, cephalosporins, or sulphonamides, if tolerated. Options:

    1. Ciprofloxacin 500 mg, PO, BID, 5-7 days.

      Ciprofloxacin 1000 mg, PO, OD, 5-7 days.

    2. levofloxacin 750 mg, PO, OD, 5-7 days.
    3. trimethoprim-sulfamethoxazole: 160/800 mg, PO, BID X 3 days.
    4. Cefadroxil 500 mg, PO, BID, 5-7 days.
  3. IV antibiotics, if sever presentation, or can't intake orally. Options:

    1. Impinenm 500 mg, IV, Q6hr, 2 weeks.
    2. Meropenem 1 g, IV, Q8hr, 2 weeks.

+/- MRSA coverage: Options:

  1. Vancomycin 15 mg/kg, IV, Q12hr, 2 weeks.
  2. Linezolif 600 mg, IV, Q12hr, 2 weeks.

Check for a response after 48 to 72 Hrs.

Re-evaluate for culture specific. treatment failure is high in; renal stone UTI, tumor, foreign body, BPH, neurogenic bladder.

PMID: 15768623, 21840265, 15630106, 11586952, 12103291, 15655743, 21292654, 16854569, AUGS


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