UTI Foundations and Therapeutics

Pathogenesis of UTIs

Endemic GI gram-negative bacteria adhere to urethral and/or bladder epithelium via fimbriae. The invasion of bacteria causes inflammation leading to UTI symptoms

Natural defenses against UTIs

Low pH (acidic), high urea/organic acids, extremes in osmolality, voiding completely, glycosaminoglycan anti-adherence molecules, lactobacillus vaginal flora (lactic acid), circulatory estrogen (decreases after menopause increases risk), and prostatic secretions in males

UTI signs and symptoms

Lower: Dysuria, urgency, frequency, nocturia, suprapubic heaviness

Upper: Flank pain, fever, nausea, vomiting, and malaise

gross hematuria

Physical exam for UTI

Costovertebral tenderness

Laboratory tests for UTI

Bacteriuria, pyuria (WBC >10), nitrite positive urine, leukocyte esterase-positive urine, antibody coated bacteria (upper)

What is necessary to diagnose a UTI

Symptoms alone are not enough. Laboratory data must be acquired

Urinalysis

Can be macro or microscopic. Includes dipstick tests like leukocyte esterase detects WBC activity or nitrite dipsticks used to detect nitrites produced by bacteria. However, these dipsticks have a 2-50% failure rate. Urinalysis can also detect hematuria, pyuria, proteinuria, and glucosuria.

Symptomatic Bacteriuria

>10² CFU coliforms/mL or >10⁵ CFU noncoliforms/mL in a symptomatic female

>10⁴ CFU bacteria/mL in a symptomatic male

Any growth of bacteria on suprapubic catheterization in a symptomatic pt.

Asymptomatic Bacteriuria

>10⁵ CFU bacteria/mL in an asymptomatic individual on two consecutive specimens

>102-5 CFU bacteria/mL in a catheterized pt.

UTI risk factors

DM, history of UTI, sex, relatives with history of UTI, diaphragm use especially with spermicide

Estrogen def., functional or mental impairment, urinary catheterization, urinary incontinence

Structural abnormalities or ureters or urethra. Intrarenal obstruction associated with nephropathy, kidney disease.

Complications of UTIs

Cystitis, pyelonephritis, renal abscess, acute urinary outlet obstruction

Pyelonephritis, kidney abscess, septic shock, chronic renal insufficiency

Cystitis → Pyelonephritis → Renal abscess → Sepsis → Septic shock → Chronic kidney damage

Uncomplicated UTI

Lower Urinary symptoms like dysuria, frequency, and urgency in otherwise healthy women.

Complicated UTI

Pregnant women, men, obstruction, immunosuppression, renal failure, individuals with risk factors, urinary retention neurologic disease, renal transplantation

Catheter associated UTI

Presence of urinary catheter with signs and symptoms of UTI.

Common pathogens of uncomplicated UTI

E.coli, Enterococcus spp., K. pneumoniae, S. saprophyticus, P. mirabilis

Common pathogens of complicated UTI

Similar to uncomplicated and recurrent.

Resistant E. coli, P aeruginosa, Acinetobacter baumannii, enterococcus and staphylococcus.

Acute systemic Prostatitis clinical presentation

High fever, chills, malaise, myalgia

Acute local Prostatitis clinical presentation

pain (perineal and rectal), urinary retention, nocturia, voiding difficulties, swollen, tender, tense, indurated

Chronic prostatitis clinical presentation

Harder to diagnose, voiding difficulties, low back pain, suprapubic discomfort, enlarged prostate

Pathology of prostatitis

Exact mechanism is unknown. pH of prostatic secretions is altered. Gram negative enteric organisms are most frequent pathogens.

Lab tests for prostatitis

UA, culture, gram stain, expressed prostatic secretions

Risk factors for prostatitis

GU infections, high risk sexual behavior, history of STI, immunocompromised

Common pathogens of prostatitis

E. Coli, Pseudomonas, klebsiella species, enterococcus species, Enterobacter’s, proteus species, and Serratia species.

UTI management considerations

Severity, site of infection, complicated vs not complicated, antibiotic susceptibility, side effect potential, cost, current antimicrobial exposure, comparative inconveniences of different therapies

Short course UTI therapies

For acute uncomplicated UTIs. Cost effective treatment does not require culture. Prevents resistance and convenient.

Acute uncomplicated cystitis, no upper tract symptoms

3 days of TMP/SMX 160/800mg po BID

Nitrofurantoin 100mg PO BID for 5 days

Urine penetrating fluoroquinolone: cefdinir 500mg PO BID 5-7 days, cipro 250mg PO BID 3 days

Who should not get short course antibiotics

Men, complicated UTI diagnosis, history of resistant UTIs, pregnant

Empiric treatment for Acute complicated cystitis with no upper tract symptoms

Ciprofloxacin 500mg PO BID 5-7 days

Levofloxacin 750mg PO daily 5-7 days

Amp/Sulbactam 1.5-3g IV q6 hours

Ceftriaxone 1g IV q24

Specific treatment for acute complicated cystitis

Nitrofurantoin, TMP/SMX, or b-lactams for 7 days

can also use nitrofurantoin for ESBL E.coli

Once cultures confirmed

Treatment for acute uncomplicated pyelonephritis (upper tract)

Cipro 500mg PO BID 7 days

Levofloxacin 750mg PO daily 5 days

TMP/SMX 160/800mg PO BID 14 days (susceptibility confirmed)

Protocol for when FQ resistance is >10% of awaiting culture results

Give 1g ceftriaxone IV

Pregnancy and UTI

When someone is pregnant their UTI is always complicated. Must always treat their bacteriuria and get C + S testing. Avoid FQs always and TMP/SMX in third trimester. Close monitoring and follow up.

UTI treatment in pregnancy

Never short course therapy.

Nitrofurantoin monohydrate/macrocrystals 100mg PO BID 5-7 days

Amoxicillin 500mg PO TID 7 days

Augmentin 500mg PO TID 7 days

Cephalexin 500mg PO BID 7 days

Recurrent UTIs

80% of the time re-infection is caused by a different organism. If there are >/= 2 episodes / 6 months it is considered recurrent. Use prophylactic TMP/SMX with lower dosing and frequency. Can consider estrogen replacement in postmenopausal women. After sex pee and single dose FQ or TMP/SMX

Relapse UTI

Only happen about 20% of the time where the same organism causes reinfection. Presumed renal involvement or structural abnormalities. Two-week course after repeat urine culture

Prevention of recurrent UTIs

Nitrofurantoin 50mg PO qhs

TMP/SMX 40/200mg PO daily

Urinary analgesics

Phenazopyridines. May mask UTI symptoms. Only administered with antibiotics. OTC form requires consultation or referral.

Estrogen replacement

Intra-vaginally helps restore normal flora. Effective in post-menopausal women.

Lactobacillus supplements

Restore normal flora in the GI and GU tract

Male UTI treatment

Always treated as complicated.

Acute: 14 days of therapy with IV antibiotics and hospitalization

Chronic: 6 weeks of therapy (likely prostatic source)

Persistently positive urine culture may require long term suppressive antibiotic therapy.

Acute prostatitis treatment

Single dose ceftriaxone 250mg IM then doxycycline 100mg PO BID 10 days

Cipro 500mg PO BID 10-14 days

Cipro 400mg IV q24

TMP/SMX 160/800mg PO BID 10-14

Chronic prostatitis

Risk vs benefit treatment

Need antibiotics that will effectively penetrate prostatic fluid to reach therapeutic concentrations. Treatment should initially be 4-6 weeks. If therapy fails, chronic suppressive therapy or surgery may be considered.