A Tour around Cystitis
(Date of publication 18 June 2004)

Statistically, at least 20% of women reading this will be familiar with the symptoms of cystitis: a need to urinate frequently, pain in the lower abdomen, discomfort during urination and blood in the urine. Bacteria are the most frequent culprit - cystitis is the single most common bacterial infection in humans - but mycobacteria, fungi and bacteria may also be responsible, and there are non-infectious causes such as radiation, chemicals and autoimmune reactions. Patient information from Harvard Medical School explains why women, especially those who are sexually active, are more susceptible than men, and incorporates a section on prevention. Suggestions include drinking plenty of fluids, urinating after intercourse and avoiding feminine hygiene products which may act as irritants.

Similar ground is covered in slightly more detail by the netdoctor site. Here, the importance of completely emptying the bladder is stressed, which is bad news for bibliophiles; sitting on the toilet and leaning forward to read makes total voiding very difficult.

By far the most common causative agent - responsible for around 90% of infections - is Escherichia coli, a normal commensal of the gut. Consulting an online textbook of bacteriology reveals that this Gram-negative facultative anaerobe is something of a microbial athlete, capable of colonising the human bowel within 40 hours of birth. There are more than 700 serotypes but only a few strains are pathogenic, causing urinary tract infections, neonatal meningitis and gastroenteritis. These strains utilise surface antigens that form projections, and are known as adhesins, to colonise the bladder. The cellular structure is clearly shown in this transmission electron micrograph of a single cell and this three-dimensional view of a colony.

The second most common cause of urinary tract infections in young, sexually active women in both Europe and the United States is Staphylococcus saprophyticus, which can be identified by its intense pigment production and resistance to novobiocin.

As we have already seen, cystitis is usually treated with a short course of antibiotics such as trimethoprim/sulfamethoxazole. However, new regulations introduced in the US last February aim to reduce the development of drug resistance by more targeted use of narrow-spectrum antibiotics for specific infections such as uncomplicated cystitis. The subject is treated very comprehensively in a US Department of Health newsletter for primary care physicians, which also provides a lot of background information about the condition itself.

The major complication of cystitis is pyelonephritis: infection of the upper urinary tract and one or both kidneys. Onset is usually sudden, with chills, fever, lower back pain, nausea and vomiting. Hospitalisation and intravenous antibiotics may be required if the patient is severely ill, and the choice of antibiotic is determined by laboratory sensitivity studies. Therapy usually comprises a two or three week course, the primary objective being permanent eradication of bacteria from the urinary tract). Untreated or recurrent kidney infection can lead to chronic pyelonephritis, with scarring of the kidneys and permanent kidney damage.

To digress for a moment, interstitial cystitis (IC) is a condition that produces similar symptoms to the bacterial infection described above but has notable differences - it is chronic, no pathogens can be detected in the urine, and the cause is unknown. Normally, the epithelium of the bladder is protected from toxins in the urine by a glycoaminoglycan (GAG) protein layer, but in IC this layer breaks down and allows toxins to irritate the bladder wall. For a more detailed hi-tech explanation, try the video here. The condition is poorly understood, but it may be an autoimmune disease and studies suggest there is also a hereditary risk factor. Other theories are that it is caused by ischaemia, an undetectable pathogen, or a deficiency of GAG in the epithelial cells.

Over time, stiffening and scarring of the bladder wall may occur. Characteristic IC lesions are glomerulations (pinpoint bleeding following recurrent irritation - see the photograph here) and Hunner's ulcers (ulcerative patches surrounded by mucosal congestion - see an example here). Treatment is aimed at relieving symptoms and most patients benefit from a combination of therapies. These include procedures such as bladder distension and instillation, transcutaneous electrical nerve stimulation (TENS), oral drugs, and surgery, such as bladder augmentation to increase its capacity. The difficulties of treatment and assessing patient response are well illustrated in this lengthy article.

Returning to bacterial cystitis, this is one area where traditional remedies have been found to have a basis in fact. For many years, cranberry juice was thought to reduce bacterial infections of the bladder and recent studies have shown that it inhibits the adherence of E. coli to the cells of the epithelial lining. A 1994 trial demonstrated that the juice decreases the incidence of bacteria and pus in the urine of elderly women, and in 2001 a Finnish study found that it reduces the occurrence of cystitis in patients with a history of urinary tract infections, attributing this effect to the presence of high levels of proanthocyanidins. However, a note of caution is sounded in a message at the bottom of the IrishHealth site, where a heartfelt plea implores sufferers "do not actually drink it during an attack of cystitis. It is far too acidic and adds to the burning sensation!"

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