Urinary Tract Infections

This is a general term which describes a bacterial infection anywhere of the urinary tract.

It is usually caused by an infection which arises from the enteric bacteria in the gut.

It is also classified as uncomplicated (normal renal structure/function) or complicated (producing a structural/functional abnormality of urinary tract)

Risk factors

Decreased urine flow – due to dehydration, or obstructions within the urinary tract

Increased bacterial entry – due to sexual intercourse, incontinence

Higher bacterial growth – diabetes, immunosuppression, catheter use, pregnancy

Female – they have a less vertical urethra making bacterial travel easier

Key tests

Urine dipstick – positive leukocyte esterase and nitrites

Urine microscopy and culture – this is the gold standard test

Blood tests – FBC, U&E and blood cultures (to assess for bacteraemia)

Ultrasound – used in patients with upper UTI and those unresponsive to treatment.

Although we can use diagnostic tests, in non-pregnant women, if they have ≥ 3 symptoms of UTI, you can treat this empirically without the requirement of more tests.

We can divide UTI’s into upper and lower UTIs:

Cystitis (lower UTI)

This is the term which describes an infection of the bladder, usually due to bacteria.

Causes

E. coli – this is a gram negative bacteria commonly found in the gastrointestinal tract

Staphylococcus saprophyticus – this is a skin commensal bacterium which has a higher incidence in young, sexually active women

Proteus mirabilis – gives alkaline urine with ammonia smell

Symptoms

Triad of dysuria (pain when urinating), urinary frequency and urgency

Suprapubic pain

Can cause a pungent urine smell +/- blood in the urine

Systemic signs like fever/vomiting are usually absent

Management

Antibiotics, e.g., nitrofurantoin or trimethoprim

Acute Pyelonephritis (upper UTI)

This describes an infection of the kidney.

Like cystitis, it is usually due to an enteric infection which ascends the tract.

Therefore, a significant risk factor is vesicoureteral reflux.

Causes

E. coli (most common), Enterococcus faecalis, Klebsiella

Symptoms

Triad of dysuria (pain urinating), urinary frequency and urgency

Loin pain

Can cause a pungent urine smell +/- blood in urine

Vomiting and fever

Hallmark is finding white cell casts in the urine

Management

Antibiotics according to local guidelines e.g., broad spectrum cephalosporin or quinolone (e.g., ciprofloxacin)