URINARY TRACT INFECTION

UTI is common in women, with about 35% having symptoms of a UTI at some time in their life. It is uncommon in children and in men, when it usually indicates an underlying urinary tract abnormality. Infections of the bladder (cystitis) can occur alone or associated with ascending infection of the ureters and renal parenchyma (pyelonephritis).

Pathogenesis

Infection of the urinary tract is most often via the ascending transurethral route, and this is facilitated by sexual intercourse and urethral catheterization.

Women are more susceptible to infection because the short urethra and its proximity to the anus facilitates the transfer of bowel organisms to the bladder. Escherichia coli is the most common cause of UTI and usually arises from the patient's own bowel flora (Table 9.5).

Abnormalities that encourage bladder infection (cystitis) include:

■ Urinary obstruction or stasis

■ Previous damage to the bladder epithelium

■ Bladder stones

■ Poor bladder emptying.

Clinical features

The symptoms of lower UTI are frequency of micturition, dysuria, suprapubic pain and tenderness, haematuria and smelly urine. The clinical features of acute pyelonephritis are loin pain and tenderness, nausea, vomiting and fever. However, localization of infection on the basis of symptoms alone is unreliable. In elderly people the symptoms may be atypical, with inconti-nence, nocturia or just a vague change in well-being.

Natural history

Uncomplicated versus complicated infection Uncomplicated infectìon refers to UTI in an otherwise healthy non-pregnant woman with a functionally normal urinary tract and will rarely result in serious kidney damage. Compli-cated infectìon refers to infection in patients with abnormal urinary tracts (e.g. stones, obstruction) or systemic disease involving the kidney (e.g. dia-betes mellitus, sickle cell disease/trait). They are more likely to fail treatment and develop complications which include renal papillary necrosis (p. 382) and the development of a renal or perinephric abscess with the risk of Gram-negative septicaemia. Most UTIs in men are also considered as complicated

Table 9.5 Organisms causing urinary tract infection in domiciliary practice

Organism

Approximate frequency (%)

Escherichia coli and other 'colitorms’

68+

Proteus mirabilis

12

Klebsiella aerogenes*

4

Enterococcus faecalis*

6

Staphylococcus saprophyticus or Staph. epidermidis†

10

*More common in hospital practice.
†More common in women.

since they are often associated with urological abnormalities such as bladder outlet obstruction in elderly men.

Acute pyelonephritis is associated with neutrophil infiltration of the renal parenchyma; small cortical abscesses and streaks of pus in the renal medulla are often present. There may be an acute deterioration in renal function but significant permanent kidney damage in adults with normal renal tracts is rare.

Retlux nephropathy (previously called chronic pyelonephritis or atrophic pyelonephritis) arises from childhood UTIs in combination with vesicoureteric reflux leading to progressive renal scarring and presenting as hypertension or CKD in childhood and adult life. Vesicoureteric reflux refers to an incom-petent valve between bladder and ureter, allowing reflux of urine up the ureter during bladder contraction and voiding. Reflux usually ceases around puberty but by that time the damage is done.

Recurrent UTI with the same or different organism more than 2 weeks after stopping antibiotic treatment is considered to be reinfection, whilst relapse is diagnosed by recurrence of bacteriuria with the same organism within 7 days of completion of treatment. Relapse implies failure to eradicate the organism usually in association with anatomical renal tract abnormality e.g. polycystic kidneys.

Investigations

The diagnosis of acute cystitis and pyelonephritis is made on the history, physical examination and urine testing.

■ Dipsticks detect the presence of urinary nitrites (bacteria breakdown nitrates to release nitrites) and leucocyte elastase. Pyuria is present in most patients with UTIs but false-negative results occur for nitrites. Dipstick tests positive for both nitrite and elastase are highly predictive of acute infection.

■ Urine microscopy and culture and antimicrobial susceptibility testing of pathogens. This is unnecessary in most women presenting with symp-toms suggestive of cystitis (in whom treatment is given based on symp-toms and dipstick testing). Criteria for diagnosis of a UTI are listed on page 361. Mixed growths are of uncertain significance and the test should be repeated. Rarely and if in doubt, urine must be obtained by suprapubic bladder aspiration, where any growth of a uropathogenic organism is evidence of infection.

■ Routine renal tract imaging of young women with UTI has a low diagnostic yield and is not indicated. Women with uncomplicated pyelonephritis who have persistent fever or clinical symptoms after 48-72 hours of appropri-ate antibiotic treatment require renal tract imaging to look for an abscess that requires drainage. Women with recurrent UTIs and all patients with complicated UTIs (see above) also require renal imaging. Contrast-enhanced CT scan gives greater anatomical detail of the renal paren-chyma and the perirenal areas than other imaging methods.

Management

Pre-treatment urine culture is desirable. In patients with an indwelling urinary catheter, antibiotic treatment is indicated only in the presence of symptoms, and should be accompanied by replacement of the catheter.

Antibiotics A 3- to 5-day course of oral amoxicillin (250 mg three times daily), nitrofurantoin (50 mg three times daily) or trimethoprim (200 mg twice daily) is usually effective. The treatment regimen is modified in light of the result of urine culture and sensitivity testing and the clinical response. Intra-venous antibiotics are indicated initially for patients with a high fever and a diagnosis of acute pyelonephritis. Oral treatment for a further 7 days is given once there is clinical improvement.

A high fluid intake (2 L daily) is advised during treatment and for some weeks afterwards.

Recurrent infection In patients with a relapse of infection a search should be made for an underlying cause and treatment of the cause if possible, e.g. removal of stones. In addition, intensive (1 week intravenous) or prolonged (6 weeks oral) antibiotics are required. Reintection where there is usually no underlying renal tract abnormality is managed initially with lifestyle advice (2 L daily fluid intake), voiding before bedtime and after intercourse, and avoidance of spermicidal jellies and constipation.

UTI in pregnancy

Approximately 6% of pregnant women have significant bacteriuria in preg-nancy; if untreated, 20% of these will develop acute pyelonephritis with significant risk to both mother and fetus (e.g. septic shock, low birthweight and prematurity). Early detection of asymptomatic bacteriuria and antibiotic treatment is necessary.

Abacteriuric frequency or dysuria
(‘urethral syndrome’)

This occurs in women and presents with dysuria and frequency but in the absence of bacteriuria. It may be associated with vaginitis in post-menopausal women, irritant chemicals (e.g. soaps) and sexual intercourse.

Tuberculosis of the urinary tract

Presentation is with symptoms of a UTI, i.e. dysuria, frequency or haematuria, and should be particularly considered in the Asian immigrant population of the UK and in countries with a high prevalence of tuberculosis. Classically, there is sterile pyuria (p. 361). Diagnosis depends on culture of mycobacteria from early-morning urine samples. Treatment is as for pulmonary tubercu-losis (p. 544).

Ebook Essentials of Kumar and Clark's Clinical Medicine, 5e

1. Ethics and communication

Ethics and communication

2. Infectious diseases

Infectious diseases

3. Gastroenterology and nutrition

Gastroenterology and nutrition

4. Liver, biliary tract and pancreatic disease

Liver, biliary tract and pancreatic disease
LIVER BIOCHEMISTRY AND LIVER FUNCTION TESTS
SYMPTOMS AND SIGNS OF LIVER DISEASE
JAUNDICE
HEPATITIS
NON - ALCOHOLIC FATTY LIVER DISEASE (NAFLD)
CIRRHOSIS
COMPLICATIONS AND EFFECTS OF CIRRHOSIS
LIVER TRANSPLANTATION
TYPES OF CHRONIC LIVER DISEASE AND CIRRHOSIS
PRIMARY SCLEROSING CHOLANGITIS
BUDD - CHIARI SYNDROME
LIVER ABSCESS
LIVER DISEASE IN PREGNANCY
LIVER TUMOURS
GALLSTONES
THE PANCREAS
CARCINOMA OF THE PANCREAS
NEUROENDOCRINE TUMOURS OF THE PANCREAS

5. Haematological disease

Haematological disease
ANAEMIA
Assessment and treatment of suspected neutropenic sepsis
HAEMOLYTIC ANAEMIA
INHERITED HAEMOLYTIC ANAEMIAS
ACQUIRED HAEMOLYTIC ANAEMIA
MYELOPROLIFERATIVE DISORDERS
THE SPLEEN
BLOOD TRANSFUSION
THE WHITE CELL
HAEMOSTASIS AND THROMBOSIS
THROMBOSIS
THERAPEUTICS

6. Malignant disease

Malignant disease
MYELOABLATIVE THERAPY AND HAEMOPOIETIC STEM CELL TRANSPLANTATION
THE LYMPHOMAS
THE PARAPROTEINAEMIAS
PALLIATIVE MEDICINE AND SYMPTOM CONTROL

7. Rheumatology

Rheumatology
COMMON INVESTIGATIONS IN MUSCULOSKELETAL DISEASE
COMMON REGIONAL MUSCULOSKELETAL PROBLEMS
BACK PAIN
OSTEOARTHRITIS
INFLAMMATORY ARTHRITIS
THE SERONEGATIVE SPONDYLOARTHROPATHIES
Clinical features, Investigations
INFECTION OF JOINTS AND BONES
AUTOIMMUNE RHEUMATIC DISEASES
SYSTEMIC INFLAMMATORY VASCULITIS
DISEASES OF BONE
THERAPEUTICS

8. Water, electrolytes and acid–base balance

WATER AND ELECTROLYTE REQUIREMENTS
BODY FLUID COMPARTMENTS
REGULATION OF BODY FLUID HOMEOSTASIS
PLASMA OSMOLALITY AND DISORDERS OF SODIUM REGULATION
DISORDERS OF POTASSIUM REGULATION
DISORDERS OF MAGNESIUM REGULATION
DISORDERS OF ACID - BASE BALANCE
THERAPEUTICS

9. Renal disease

Renal disease
INVESTIGATION OF RENAL DISEASE
GLOMERULAR DISEASES
NEPHROTIC SYNDROME
URINARY TRACT INFECTION
TUBULOINTERSTITIAL NEPHRITIS
HYPERTENSION AND THE KIDNEY
RENAL CALCULI AND NEPHROCALCINOSIS
URINARY TRACT OBSTRUCTION
ACUTE RENAL FAILURE/ACUTE KIDNEY INJURY
CHRONIC KIDNEY DISEASE
RENAL REPLACEMENT THERAPY
CYSTIC RENAL DISEASE
TUMOURS OF THE KIDNEY AND GENITOURINARY TRACT
DISEASES OF THE PROSTATE GLAND
TESTICULAR TUMOUR
URINARY INCONTINENCE

10. Cardiovascular disease

COMMON PRESENTING SYMPTOMS OF HEART DISEASE
INVESTIGATIONS IN CARDIAC DISEASE
CARDIAC ARRHYTHMIAS
HEART FAILURE
ISCHAEMIC HEART DISEASE
RHEUMATIC FEVER
VALVULAR HEART DISEASE
PULMONARY HEART DISEASE
MYOCARDIAL DISEASE
CARDIOMYOPATHY
PERICARDIAL DISEASE
SYSTEMIC HYPERTENSION
ARTERIAL AND VENOUS DISEASE
ELECTRICAL CARDIOVERSION
DRUGS FOR ARRHYTHMIAS
DRUGS FOR HEART FAILURE
DRUGS AFFECTING THE RENIN - ANGIOTENSIN SYSTEM
NITRATES, CALCIUM - CHANNEL BLOCKERS AND POTASSIUM - CHANNEL ACTIVATORS

11. Respiratory disease


Respiratory disease
TUBERCULOSISnd
DIFFUSE DISEASES OF THE LUNG PARENCHYMA
OCCUPATIONAL LUNG DISEASE
CARCINOMA OF THE LUNG
DISEASES OF THE CHEST WALL AND PLEURA
DISORDERS OF THE DIAPHRAGM

12. Intensive care medicine

Intensive care medicine

13. Drug therapy, poisoning, and alcohol misuse

Drug therapy, poisoning, and alcohol misuse

14. Endocrine disease

Endocrine disease
PITUITARY HYPERSECRETION SYNDROMES
THE THYROID AXIS
MALE REPRODUCTION AND SEX
FEMALE REPRODUCTION AND SEX
THE GLUCOCORTICOID AXIS
THE THIRST AXIS
DISORDERS OF CALCIUM METABOLISM
DISORDERS OF PHOSPHATE CONCENTRATION
ENDOCRINOLOGY OF BLOOD PRESSURE CONTROL
DISORDERS OF TEMPERATURE REGULATION
THERAPEUTICS

15. Diabetes mellitus and other disorders of metabolism

DIABETES MELLITUS
DIABETIC METABOLIC EMERGENCIES
COMPLICATIONS OF DIABETES
SPECIAL SITUATIONS
HYPOGLYCAEMIA IN THE NON - DIABETIC
DISORDERS OF LIPID METABOLISM
THE PORPHYRIAS

16. The special senses

THE EAR
THE NOSE AND NASAL CAVITY
THE THROAT
THE EYE

17. Neurology

COMMON NEUROLOGICAL SYMPTOMS
COORDINATION OF MOVEMENT
THE CRANIAL NERVES
COMMON INVESTIGATIONS IN NEUROLOGICAL DISEASE
UNCONSCIOUSNESS AND COMA
STROKE AND CEREBROVASCULAR DISEASE
EPILEPSY AND LOSS OF CONSCIOUSNESS
NERVOUS SYSTEM INFECTION AND INFLAMMATION
HYDROCEPHALUS
HEADACHE, MIGRAINE AND FACIAL PAIN
SPINAL CORD DISEASE
DEGENERATIVE NEURONAL DISEASES
DISEASES OF THE PERIPHERAL NERVES
MUSCLE DISEASES
MYOTONIAS
DELIRIUM
THERAPEUTICS

18. Dermatology

Dermatology

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