Urinary tract infections
A urinary tract infection (UTI) is a bacterial infection that affects part of the urinary tract. When it affects the lower urinary tract, it is known as a simple cystitis (bladder infection), and when it affects the upper urinary tract, it is known as pyelonephritis (kidney infection). Symptoms of lower urinary tract infections include painful urination, and frequent or urge to urinate, either alone or in combination. Symptoms of pyelonephritis, in addition to those of lower urinary tract infection, include fever and dysthymia (pain in the side of the body). In the elderly and very young, the symptoms may be vague and nonspecific. The main pathogen of both types is E. coli, while other bacteria, viruses or fungi may be rarely the cause.
Urinary tract infections, which occur more frequently in women than in men, are found in half of women who have had at least one urinary tract infection at some time in their lives. Recurrence is common. Risk factors include female anatomy, sexual intercourse, and family history of the disease. Pyelonephritis, if it occurs, also often follows bladder infection, but may also arise from hematogenous spread of infection. In young, healthy women, the diagnosis can be made on the basis of symptoms alone. In patients with ill-defined symptoms, diagnosis may be difficult because bacteria may be present without infection. In complicated cases or in cases of treatment failure, urine cultures may be useful. In patients with frequent infections, low doses of antibiotics may be used as a prophylactic measure.
In uncomplicated cases, urinary tract infections are easily treated with a short course of antibiotics, although resistance to the antibiotics used to treat this disease is increasing. In complicated cases, a longer course or intravenous antibiotics may be required, and further diagnostic testing is needed if symptoms do not improve two or three days after treatment. In women, urinary tract infections are the most common form of bacterial infection, with 10% of all bacterial infections being urinary tract infections each year.
Signs
Lower urinary tract infections are also known as bladder infections. The most common symptoms are burning sensation in urination, frequent urination (or urge to urinate) in the absence of vaginal discharge and significant pain. These symptoms may vary from mild to severe and, in healthy women, last an average of 6 days. There may be some pain above the pubic bone or down the back. Patients with upper urinary tract infection or pyelonephritis may have dystocia (on both sides of the body), fever, nausea, and vomiting in addition to the typical symptoms of lower urinary tract infection. Rarely, there is hematuria or purulent urine (pus in the urine).
In children, fever may be the only symptom of urinary tract infection (UTI) in children. Due to the lack of more obvious symptoms, many medical societies recommend urine cultures when a fever develops less than once a year in girls under two years of age or in uncircumcised boys (6 to 12 years). Infants may eat poorly, vomit, sleep a lot, or show signs of jaundice. In older children, new-onset urinary incontinence (loss of bladder control) may occur.
Urinary tract symptoms are often lacking in older adults. Manifestations may be vague, such as urinary incontinence, changes in mental status, or the only symptom may be fatigue. However, sepsis, bloodstream infections, may also be seen as the first symptom. Diagnosis can be complicated by the fact that many older adults have prior incontinence or dementia.
Causes
E. coli is the cause of 80-85% of urinary tract infections and Staphylococcus putrefaciens is the cause in 5-10%. They may rarely be caused by viral or fungal infections. Other bacterial infections include Klebsiella spp, Aspergillus spp, Pseudomonas spp and Enterobacter spp. These are uncommon and are usually associated with urinary tract abnormalities or urethral catheterization. Urinary tract infections caused by Staphylococcus aureus are often secondary to bloodstream infections.
Gender
In sexually active young women, sexual activity is the cause of 75-90% of bladder infections, and the risk of infection correlates with the frequency of sexual intercourse. The term “honeymoon cystitis” has been applied to the phenomenon of frequent urinary tract infections during early marriage. In postmenopausal women, sexual activity is not associated with the risk of getting a urinary tract infection. The use of spermicide, which is not governed by sexual frequency, increases the risk of UTIs.
Women are more likely than men to develop urinary tract infections because in women, the urethra is much shorter and closer to the anus. The increased risk of urinary tract infections in women with decreased estrogen levels during menopause is due to the loss of protective vaginal flora.
Catheter urethral catheterization increases the risk of urinary tract infections. The risk of bacteriuria (bacteria in the urine) is between 3 and 6% per day and prophylactic antibiotics are ineffective in reducing the symptoms of infection. Catheter insertion can reduce the risk of associated infections only if necessary, using aseptic technique for insertion and keeping the catheter airtight for unobstructed drainage.
Other bladder infections have a tendency to spread through the home. Other risk factors include diabetes, being uncircumcised, and having a large prostate. Complicating factors are quite vague and include anatomical, functional or metabolic abnormalities of vulnerability. Treatment of complicated urinary tract infections is more difficult and usually requires more aggressive evaluation, treatment and follow-up. Urinary tract infections in children are associated with vesicoureteral reflux (abnormal movement of urine from the bladder into the ureter or kidney) and constipation.
People with spinal cord injury are at increased risk for urinary tract infections, partly due to prolonged catheter use and partly due to voiding dysfunction, which is the most common cause of infection in this population, as well as the most common cause of hospitalization. In addition, the use of cranberries and their juices appears to be ineffective in both prevention and treatment in this population.
Pathogenesis
The bacteria that cause urinary tract infections usually enter the bladder via the urethra. However, infection may also occur through the bloodstream or lymph. It is believed that bacteria are often transported from the intestine to the urethra, and women are at greater risk due to their anatomy. Once inside the bladder, E. coli can attach to the bladder wall and form a biofilm that resists the body’s immune response.
Prevention
Many measures (not proven) affect the frequency of UTI, including: the use of birth control pills or condoms, urination immediately after intercourse, type of underwear, personal hygiene methods after urination or defecation, usually washing or showering. There is also a lack of evidence for holding urine, tampon use, and irrigation, again.
Frequent urinary tract infections use spermicide as a method of contraception and they are advised to use alternative methods. Cranberry (juice or capsules) may reduce the incidence of frequent infections, but long-term tolerability is an issue, with Cranberry causing gastrointestinal distress occurring in more than 30% of cases, and twice-daily use may be preferable to once-daily use. As of 2011, further research is needed to determine whether vaginal probiotics are beneficial. Condom use without spermicide or use of birth control pills does not increase the risk of simple urinary tract infections.
Medications For recurrent infections, a long course of daily antibiotics is effective, and frequently used medications include furantoin and methoxypyrimethamine/sulfamethoxazole. Urotropine (hexamethylenetetramine) is another agent commonly used for this purpose, in the bladder, where acidity is low and the drug produces formaldehyde, which (bacteria) cannot resist. In some cases, the infection is associated with sexual intercourse, after which the administration of antibiotics may be useful. In postmenopausal women, topical intravaginal estrogen has been found to reduce recurrence. The use of vaginal estrogen with a uterine depressor, as opposed to a topical cream, is not as useful as a low dose of antibiotics. As of 2011, many vaccines are in development.
Pediatric evidence suggests that prophylactic antibiotics do not reduce urinary tract infections in children. Recurrent urinary tract infections are rarely the cause of further renal problems without underlying renal abnormalities, resulting in less than one-third of one percent (0.33%) of adults with chronic kidney disease.
Simple cases can be diagnosed and given treatment based on symptoms alone without further laboratory confirmation. In complex or questionable cases, it may be useful to confirm the diagnosis with a urine test looking for the presence of urinary nitrite, leukocytes (white blood cells), or leukocyte esterase. In another test, a urine microscope to look for the presence of red blood cells, white blood cells, or bacteria. A urine culture is considered positive if it shows a colony count greater than or equal to 103/ml live count of a typical urinary tract infection microorganism. Antibiotic susceptibility to these cultures can also be tested and used to select antibiotic therapy. However, women with negative bacterial cultures may still improve with antibiotic therapy. In the elderly, diagnosis may be difficult because symptoms may be vague and because there are no reliable tests for urinary tract infections.
A classified urinary tract infection may involve only the lower urinary tract, in which case it is known as a bladder infection. Or, it may involve the upper urinary tract, called pyelonephritis. If the urine contains meaningful bacteria, but there are no symptoms, it is called asymptomatic bacteriuria. A urinary tract infection is considered complicated if it includes the upper urinary tract, is in a diabetic person, or a pregnant woman, or is in a male, or in an immunocompromised person. Otherwise, if the woman is healthy and premenopausal, it is considered uncomplicated. In children, when a urinary tract infection is associated with fever, it is considered to be an upper urinary tract infection.
Children In order to diagnose urinary tract infections in children, positive urine cultures are necessary. Contamination poses a frequent challenge depending on the urine collection method used, thus 105 CFU/mL is permitted for net concentrated segmental urine samples, 104 CFU/mL for catheter-derived samples, and 102 CFU/ML is used for suprapubic transcystic samples (samples aspirated directly from the bladder with a needle). The World Health Organization does not advocate the use of “urine bags” for sample collection for urine culture because of the high contamination rate, and catheterization is preferred for those who are not toilet trained. Some, such as the American Academy of Pediatrics, recommend renal ultrasound and voiding urethrocystography (looking at real-time X-rays of the urethra and bladder as a person urinates) for all children younger than 2 years of age who have a urinary tract infection. However, even when problems are identified, effective treatment is lacking, so others, such as the National Institute for Clinical Effectiveness in the UK, recommend routine imaging in those less than 6 months of age or with abnormal findings.
Differential diagnosis
In women with cervicitis (inflammation of the cervix) or vaginitis (inflammation of the vagina) and young men with symptoms of urinary tract infection, Chlamydia trachomatis or Neisseria gonorrhoeae gonorrhoeae infection may be the cause. Vaginitis may also be due to yeast infection, and interstitial cystitis (chronic pain in the bladder) is thought to be the cause in those who experience multiple episodes of urinary tract infection symptoms, but have negative urine bacterial cultures that do not improve with antibiotics. Prostatitis (inflammation of the prostate) should also be considered in the differential diagnosis.
Treatment
The main pillar of treatment is antibiotics. In the first few days, in addition to antibiotics, fenapyridine is occasionally prescribed to help with the burning and urgency sometimes experienced by patients with bladder infections. However this drug is not routinely recommended because of the safety issues associated with its use. In particular, the risk of methemoglobinemia (higher than normal levels of methemoglobin in the blood) is high. Acetaminophen (paracetamol) can be used for fever.
Women with recurrent simple urinary tract infections may benefit from self-treatment only if initial treatment has failed, when symptoms occur and medical follow-up is done. Antibiotic prescriptions can be delivered by phone to the pharmacist for pickup.
Uncomplicated uncomplicated infections can be diagnosed and treated based on symptoms alone. Oral antibiotics such as methotrexate/sulfamethoxazole (TMP/SMX), cephalosporins, furantoin, or fluoroquinolones are equally effective and greatly reduce the time to recovery. A three-day treatment with methotrexate, TMP/SMX, or fluoroquinolones is usually sufficient, while furantoin takes 5-7 days. With treatment, symptoms should improve within 36 hours and approximately 50% of people will be cured without days or weeks of treatment. The American College of Infectious Diseases does not recommend fluoroquinolones as a first treatment drug due to concerns about developing resistance to this class of drugs. Despite this precaution, some drug resistance has occurred due to widespread use of these drugs. In some countries, methotrexate is considered equivalent to TMP/SMX. simple urinary tract infections, children often respond to both with a 3-day course of antibiotics.
Treatment of pyelonephritis is more aggressive than a simple bladder infection. Either a longer period of oral antibiotics or intravenous administration is required. The oral fluoroquinolone ciprofloxacin is usually used for seven days if the local resistance rate is less than 10%, and intravenous ceftazidime is often given if the local resistance rate is greater than 10%. In those exhibiting more severe symptoms, admission to the hospital is necessary for further antibiotic treatment. If symptoms do not improve after two or three days of treatment, complications such as kidney stones and urinary tract obstruction may be considered.
Epidemiology Urinary tract infections are the most common bacterial infection in women. It occurs most frequently between the ages of 16 and 35, with 10% of women having an annual infection and 60% having an infection at some point in their lives. Recurrence is common, with nearly half of those with a first infection having a second infection within a year. Urinary tract infections occur 4 times more frequently in women than in men, and pyelonephritis occurs between 20 and 30 times more frequently. They are the most common cause of hospital-acquired infections, accounting for about 40% . The rate of asymptomatic bacteriuria increases with age, from 2% to 7% in women of childbearing age to as high as 50% in older women in nursing homes. Asymptomatic bacteriuria accounts for 7-10% of men over the age of 75.
Urinary tract infections in childhood may affect 10% of the population. Childhood urinary tract infections are most common in uncircumcised boys less than 3 months of age, followed by girls less than 1 year of age. The frequency of urinary tract infections among children is estimated to be broad. Among children with fever symptoms, between the ages of birth and two years, 2 to 20% were diagnosed with a urinary tract infection.
Socioculturally in the United States, the office visited nearly 7 million people with urinary tract infections, one million emergency department visits, and 100,000 hospitalizations annually. The cost of these infections is considerable, both in terms of time lost from work and in the cost of medical care. In the United States, the direct cost of treatment is estimated at $1.6 billion per year.
The history of urinary tract infections was first described in the ancient medical text of Abes, written in 1550 BC. It was described by the Egyptians as “heat emanating from the bladder”. Until the 1930s, when antibiotics were developed and used, there was no effective treatment. Before that, there were only such means as herbs, bloodletting and rest.
The increased focus on urinary tract infections in pregnant women is due to the increased risk of kidney infections. During pregnancy, elevated levels of progesterone increase the risk of reduced ureteral and bladder muscle tone, leading to a greater likelihood of reflux, the flow of urine from the ureter back to the kidneys. There is no increased risk of asymptomatic bacteriuria in pregnant women, and if bacteriuria is present, there is a 25-40% risk of kidney infection. Therefore, if the urine tests for signs of infection, even in the absence of symptoms, treatment is recommended. Cefadroxil or furantoin is usually used, as it is generally considered safe for use in pregnant women. Kidney infections during pregnancy may lead to preterm labor or preeclampsia (high blood pressure during pregnancy, renal insufficiency, which can present in a sudden state).