Lower urinary tract infectious disease

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

Treatment: Empirical treatment for non-critical lower UTI


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.


In females, ascending infection from the vagina through the urethra is the most common. Urinary incontinence increases the risk.


  1. Cystitis: dysuria, urinary frequency, urinary urgency, suprapubic pain, nocturia, pus-urine, and may associated with hematuria (rare).

  2. Genital pruritus or discharge.


  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.

  3. Pelvic CT for upper UTI.

    • US or IV Urogram.

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.

  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,

Targeted organisms:

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

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.

NOTE: Treating physicians should have high sensitivity toward sepsis risk, especially, if patient start to vitally deteriorate.

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

1st line:

Option 1: Nitrofurantoin: 100 Mg, PO, BID X 4-7 days.

AE: Headach, Nausea. It has poor tissue penetraton; not recommended if prostatits was associated.

Option 2: trimethoprim-sulfamethoxazole: 160/800 mg, PO, BID X 3 days.

It has poor tissue penetraton; not recommended if prostatits was associated. Not recommended if E.coli has a history of resistance in your local community.

Option 3: fosfomycin: 3 g mixed in water, OD, STAT.

AE: Headache, Diarrhea.

Option 4: pivmecillinam: 400 mg, PO, BID X 5 days.

AE: Diarrhea, nausea

2nd line:

Option 5: Beta- lactamase: 1. Amoxicillin/clavunate 500 mg, PO, BID, 5-7 days. 2. Cefadroxil 500 mg, PO, BID, 5-7 days.

3ed line:

Option 6: Floruquines: 1. Ciprofloxacin 250 or 500 mg, PO, BID, 3 days. 2. Levofluxacin 250 mg, PO, BID, 3 days.

Reserve for sever infection profile. AE: Neuromuscular & skeletal: Musculoskeletal.

PMID: 21292654, 22318279, AUA/CUA/SUFU Guideline (2019)


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