Urinary Tract Infections

Most common route of UTI infection

Ascending (urethra upward)

Descending UTI route

Uncommon; bloodstream seeds urinary tract

Host defenses against UTI

Low urine pH, high osmolality, high urea, prostatic secretions, low vaginal pH (Lactobacillus)

UTI risk factors

Female, prior UTI, sex, pregnancy, menopause/spermicides, young/old age, catheter/enlarged prostate, poor hygiene

Classic UTI symptoms

Urgency, frequency, dysuria, cloudy/bloody urine, pelvic pain

Pyelonephritis symptoms

UTI symptoms + fever/chills, N/V, flank pain, hematuria

Prostatitis symptoms

Fever/chills, malaise, pain, dysuria, urgency, nocturia, retention

Urinalysis findings of UTI

Bacteriuria, pyuria (WBC >10), nitrite +, leukocyte esterase +

When to collect UA + urine culture

BEFORE starting antibiotics

Urine culture timing

Culture 1–2 days; susceptibilities 2–3 days

Most common UTI pathogen

E. coli (80–90%)

Community-acquired UTI pathogens

E. coli, Klebsiella, S. saprophyticus, E. faecalis

Hospital-acquired/cUTI pathogens

E. coli, Pseudomonas, Proteus, Enterobacter, Enterococcus

Catheter/neurogenic bladder pathogens

More resistant: Pseudomonas, Enterococcus

Prostatitis pathogens

E. coli, Klebsiella, Proteus, Enterococcus

Uncomplicated UTI definition

Bladder only; no fever, flank pain, or catheter

NOT complicated on their own

Male, diabetes, immunocompromise, BPH

Complicated UTI definition

Beyond bladder: fever, flank pain, prostatitis, obstruction, catheter

Nitrofurantoin (Macrobid) dose – uUTI

100 mg BID x 5 days

Nitrofurantoin pearls

Bladder only; avoid if CrCl <60; NOT for cUTI/pyelo

Bactrim DS dose – uUTI

160/800 mg BID x 3 days

Bactrim pearls – uUTI

Only if local resistance <20%; SJS/TEN, hyperkalemia

Fosfomycin (Monurol) dose

3 g once

Fosfomycin pearl

Inferior to other regimens; NOT for cUTI

Oral β-lactams for uUTI

Amox-clav, cefdinir, cefaclor, cefpodoxime x 3–7 days

Oral β-lactam pearls – uUTI

Only if others can't be used; inferior; OK in pregnancy

Cipro dose – uUTI

500 mg BID x 3 days

Cipro pearls – uUTI

Renally adjust, QTc, more ADRs; save for cUTI

Phenazopyridine (Azo)

200 mg TID, max 3 days; urinary analgesic

Non-drug UTI prevention

Cranberry, probiotics, hydration (prevent, don't cure)

Topical estrogen

Postmenopausal women; prevention only

Recurrent UTI definition

2 in 6 months or 3 in 1 year

Relapse vs. reinfection

Relapse <2 weeks; reinfection >2 weeks

FQ dose – cUTI

Cipro 500–750 mg BID or levo 750 mg daily x 5–7 days

FQ pearl – cUTI

Preferred oral; avoid if FQ in past 12 months or FQ-resistant isolate

Bactrim DS dose – cUTI

160/800 mg BID x 7 days

Bactrim pearl – cUTI

Preferred if susceptible; high resistance, check prior cultures

Oral β-lactam pearl – cUTI

Alternative only; high doses; avoid cefdinir/cefaclor

Nitrofurantoin/fosfomycin in cUTI

NOT appropriate (don't reach kidney/blood)

Ceftriaxone susceptibility and cefpodoxime

Does NOT predict cefpodoxime susceptibility

cUTI empiric approach steps

1) Severity (SOFA ≥2) 2) Resistance risk 3) Patient factors 4) Antibiogram (sepsis only)

Antibiogram susceptibility cutoff

≥80% sepsis; ≥90% septic shock

Preferred cUTI IV (sepsis or not)

3rd/4th gen cephs, pip-tazo, FQs

Carbapenems in cUTI

Preferred if sepsis; alternative if not; consider if prior ESBL

Aminoglycosides in cUTI

Alternative; 1–2 doses if ESBL concern

Ceftriaxone vs. cefepime in cUTI

Ceftriaxone if no Pseudo concern; cefepime/ceftaz if Pseudo; avoid ceftriaxone if prior ESBL

Pip-tazo dose – cUTI

4.5 g q8h

Newer agents (cefiderocol, novel BL/BLIs)

Reserve for resistant pathogens

IV-to-PO switch criteria

Improving, tolerating PO, effective oral option

cUTI duration

FQ: 5–7 days; non-FQ: 7 days

Gram-neg bacteremia from urine – duration

7 days (not 14)

cUTI duration is counted from

First day of effective therapy

Prostatitis duration

2–4 weeks

Prostatitis drugs

FQs (best studied) or Bactrim (penetrate prostate)

Bactrim limitation in prostatitis

Weak vs. Enterococcus; no Pseudomonas

UTI rule in pregnancy

Treat all UTIs + asymptomatic bacteriuria (≥100,000 CFU/mL)

Preferred UTI drug in pregnancy

Cephalexin x 5–7 days

Other pregnancy UTI options

Amox-clav (high resistance), nitrofurantoin, fosfomycin (not for pyelo)