Urinary Tract Infection (UTI)

Urinary Tract Infection (UTI)

Incidence

<2yo – M>F

↓11 yo - 5% female; 1% male à 50% recurrent within a year

Lifetime prevalence

·         30% in female

·         1% in male

Definition

1.       Bacteriuria

Bacteria in the urine

2.       UTI

Presence of pure growth of bacteria > 10⁵ organisms /ml of fresh MSU

3.       Recurrent UTI

Further infection with new organism

4.       Relapse

Further infection with same organism

5.       Abacterial cystitis or urethral syndrome

Symptoms suggestive of a lower urinary tract infection but in the absence of significant bacteruria

Up to 1/3 of women with symtoms have bacteriuria

UTI sites

1.       Cystitis

2.       Pyelonephritis

3.       Prostatitis

4.       Urethritis

Classification

1.       Uncomplicated               Normal renal tract and function

2.       Complicated

·         Abnormal renal /GU tract

·         ↓renal function

·         Impaired host defense

·         Virulent organism e.g. Staph. Aureus

Risk factors

1.       Female – dt short urethra

2.       Uncircumsized (male): 5-12 X risk

3.       Sexual intercourse

4.       Exposure to spermicide (by diaphram or condom)

5.       Pregnancy

6.       Menopause

7.       ↓host defense

·         Immunosuppresion

·         DM

8.       Urinary tract

                                I.            Obstruction

1.       Luminal

§  Stone

§  blood clots

§  sloughed papilla

§  tumor – renal, ureteri, bladder

2.       Mural

§  Congenital/acquired stricture

§  Neuromuscular dysfunction

§  schistomiasis

3.       Extra-mural

§  Abdominal/pelvic mass

§  Retroperitoneal fibrosis

                              II.            Catheter

                            III.            Malformation   -VUR

Organisms

         i.            E.coli (>70% in community; <40% in hospital)

       ii.            Staph saprophyticus

      iii.            Proteus mirabilis

·         In male (under prepuce)

·         Cause stone formation (phosphate stone)

o   Breakdown ammonia àalkalinising urine

Rarer

1.       Staph aureus

2.       Pseudomonas aeruginosa

·         A/w structural abnormalities àin urinary tract (affect drainage)

3.       Enterococcus faecalis

4.       Klebsiella

5.       Enterobacter

6.       Acinetobacter sp

7.       Serratia marascens

8.       Candida albicans

	Cystitis	Acute Pyelonephritis	Prostatitis
Symptoms	frequency, dysuria, urgency, strangury, haematuria, suprapubic pain	high fever, rigor, vomiting, loin pain, tenderness and oliguria (if ARF)	flu-like symptoms, low backache, few urinary symptoms,  swollen and tender prostate on PR
	Fever Abdominal / loin pain Distended bladder Enlarged prostate Foul smelling urine
Treatments	Trimethoprim 200mg/12h PO (M 7d, F 3d). Alternative cefalexin 1g/12h 2nd line ciprofloxacin or co-amoxiclav PO x7/7	Cefuroxime 1.5g/8h IV, then PO x7d	Ciprofloxacin 500mg/12h PO for 4weeks
	Drink plenty of water Urinate often

Test

Urine

1.       Urine dipstick - +ve leucocytes, nitrates

2.       MSU –C&S

(pure growth of > 10⁵ organisms /ml is diagnostic; still significant if < 10⁵ organisms /ml and pyuria >20WBC/mm³)

Blood

·         FBC, U&E,  CRP, blood cultures

US or IVU or cystoscopy

Indication

1.       UTI in children

2.       Men

3.       Failure to respond to treatment

4.       Recurrent UTI (>2/year)

5.       Pyelonephritis

6.       Unusual organism

7.       Persistent haematuria

Discussion

Causes of sterile pyuria

·         Renal TB

Other causes

1.       Treated UTI <2w prior

2.       Inadequately treated UTI

3.       Appedicitis

4.       Calculi

5.       Prostatitis

6.       Bladder tumor

7.       UTI with fastidious culture requirements

8.       Papillary necrosis (e.g. DM, analgesic excess)

9.       Tubulointerstitial nephritis

10.   Polycystic kidney

11.   Chemical cystitis (e.g. cyclophosphamide)