Do I Always Need Antibiotics for a UTI?

Urinary system infections in the elderly

Urinary system infection (senile infection in urinary system) is a common disease in the elderly, ranking second only to respiratory infections among infectious diseases in the elderly.

Urinary system infections in the elderly Epidemiology of urinary system infections in the elderly

Uti can be seen at any age, but its incidence increases significantly with age, especially in women and inpatients. According to foreign literature reports, the prevalence of UTI in general adult women ranges from 3% to 4.5%, and increases to 15% to 20% by the age of 65 years. UTI rarely occurs in men before the age of 50, but reaches 65 to 70. At the age of 3, 4% to 4% are ill. After 70 years of age, the prevalence of UTI can reach more than 20%. Regardless of gender, the prevalence of uti in the elderly can increase by as much as 25% to 50% when in a chronic debilitating state or when bedridden for long periods of time. The results reported in China are similar to those in foreign countries. In addition, some authors have observed that about two-thirds of urinary tract infections in the elderly occur during hospitalization and are nosocomial infections.

Etiology of urinary system infection in the elderly

The main pathogenic strains of elderly uti are Escherichia coli and Proteus, followed by Pseudomonas aeruginosa and Proteus, Klebsiella, Alcaligenes and other Gram-negative bacteria. In recent years, people have noticed that uti caused by Gram-positive cocci (such as staphylococcus and enterococcus) is also common in the elderly. In the elderly with abnormal structure or function of the urinary system, the infection of fungi (predominantly Candida albicans) or type 1 bacteria increased significantly. Elderly patients with weak constitution or long-term bedridden can also cause severe UTI caused by various non-urinary tract pathogens or condition pathogens. In addition, acute urethral syndrome in older women is partly caused by chlamydia.

The exact mechanism of susceptibility to uti in the elderly is not completely clear. The following factors are known to be relevant:

1. Increased sensitivity of urinary tract epithelial cells to bacteria in elderly. Different authors have observed this phenomenon in elderly men and elderly women, especially women. The reason is not clear, it is speculated that it may be related to changes in estrogen levels, and estrogen stimulation may increase the density of bacterial receptors on the cell surface and increase the cell adhesion activity.

2. The factors of urinary tract obstruction and poor urinary flow in the elderly are significantly increased, making bacteria easy to survive and reproduce. Older people often have urinary tract incompleteness or complete obstruction due to prostatic hyperplasia or bladder neck obstruction, urinary tract stones, tumors and other reasons. The probability of developing a neurogenic bladder or a weak bladder is also significantly increased. These factors can lead to poor urinary flow, increased residual urine in the bladder, and reduced local antibacterial power of urothelial cells, which is prone to infection.

3. Decline of the overall and local immune response ability of the elderly Due to aging, the humoral immunity and cellular immune function of the elderly are significantly reduced, making them less able to respond to infection and other stress factors. At the same time, elderly kidney and bladder membranes are in a relatively ischemic state, and pelvic muscle relaxation and habitual constipation can further aggravate poor blood circulation in local mucous membranes and reduce prostate secretion in elderly men, all of which weaken their local resistance. In addition, the degenerative changes of the elderly kidney are also one of the reasons for the decline in the urinary tract mucosal defense mechanism.

4. Other elderly people have reduced physical thirst, decreased drinking water, and changes in renal tubular urine concentration and dilution functions. At the same time, the elderly are often accompanied by systemic diseases such as hypertension and diabetes, with increased rates of malnutrition and prolonged bed rest, and often abuse painkillers, non-steroidal anti-inflammatory drugs, etc. due to the disease, which easily leads to UTI and even chronic interstitial nephritis Or chronic pyelonephritis.

Urinary system infections in the elderly Pathogenesis of urinary system infections in the elderly

The elderly's immune function declines and their ability to resist infection is insufficient, which plays an important role in the pathogenesis of urinary tract infections. And the elderly are often accompanied by systemic diseases such as hypertension, renal artery and renal arteriolar sclerosis, diabetes, etc. In addition, the renal tubular function and bladder function of the elderly decrease with age, which also affects urination and defecation. These are all participating factors that have a high incidence of urinary tract infections in the elderly, recurrent episodes, and are difficult to cure. The renal tubule function of the elderly is reduced, showing a decrease in water and sodium transport function and a decrease in the ability to concentrate urine. Radioimmunoassay for increased 2-mg in urine can sensitively reflect the decline in renal tubular function in the elderly after excluding other various diseases. The urinary osmotic pressure of healthy elderly is 500-700mmol / l, and the ratio of urine and blood osmotic pressure and the clearance rate of pure water (ch2o) are lower than those of young people. In addition, the elderly have reduced metabolic functions of drugs excreted through the kidney, which can easily lead to tubule drug poisoning and chemical damage. On this basis, it is more likely to cause upper urinary tract infection. The lower urinary tract becomes abnormal with aging, showing abnormal urination, increased urination frequency at night and day. Brocklehurst et al. found that 70% of men and 60% of women in the elderly have increased nocturia, and men have more urgency, and women often have difficulty urinating, incontinence, and stress urinary incontinence. Asymptomatic older people also gradually slow down their urination rate. The maximum urination rate of the elderly over 65 years is> 13ml / s, which is a normal range. The physiological basis that affects the urinary speed of the elderly is not fully understood, but it must be the result of a variety of factors. In addition, local structural changes, such as high incidence of elderly kidney cysts, kidney stones, mechanical urinary tract obstruction, bladder ureteral reflux, decreased cardiac output from cardiovascular disease, and neurological bladder from cerebrovascular disease, all affect the lower urinary tract. Speed and volume of urination, and easily lead to urinary tract infections.

Clinical manifestations of urinary tract infections in the elderly

The clinical manifestations of elderly patients with UTI are not typical. Most elderly patients with UTI have non-renal symptoms, such as fever, lower abdominal discomfort, lumbosacral pain, loss of appetite, lower extremity cold, spontaneous sweating, night sweats, etc. Only manifested as fatigue, dizziness, insomnia, or consciousness. Therefore, judging the presence or absence of uti in the elderly based on clinical manifestations is highly prone to misdiagnosis or missed diagnosis, so urine tests and bacterial culture should be done in a timely manner. In addition, the majority of elderly uti are chronic refractory infections, with a higher recurrence rate and reinfection rate.

Urinary system infections in the elderly

Elderly UTI is prone to bacteremia, sepsis, and toxic shock due to infection. It is the main cause of septicemia in the elderly (approximately one-third), and it should cause clinicians to be vigilant.

Urinary system infection in the elderly Laboratory examination of urinary system infection in the elderly

1. Urinalysis Increased urinary leukocyte excretion indicates urinary tract inflammation and is also of great significance in diagnosis. The correlation between leukocyte urine and urinary tract infection has long been recognized. The incidence of pyuria in asymptomatic bacteriuria is about 37%. Leukocyte excretion> 10 cells / mm is abnormal.

Sterile pyuria is also a manifestation of renal tuberculosis, stones, analgesic abuse, a few aerobic and anaerobic infections. Urinary tract injuries such as chlamydia urethritis, glomerulonephritis and nephropathy can also be seen with sterile pyuria.

Urinary tract infection without pyuria is seen in leukocytopenia caused by drugs and aplastic anemia, and infectious lesions in the distal renal collecting system (such as renal cortical abscess), and occasionally obstructive urinary tract disease.

Leukocyte urine is not a constant feature of urinary tract infections, and the white blood cell count of urine samples from several consecutive times may vary. The absence of white blood cells in a single urine specimen should not be considered evidence of sterile urine. Pyuria depends on urine flow and urine pH. Urine bacterial counts can also vary within one day. In general, morning urine samples should be examined.

Leukocyte casts are reliable evidence of inflammatory diseases of the upper urinary tract, but like granular casts are not unique to infection. These casts are not common in active pyelonephritis. Fresh cast urine specimens must be used for cast counting.

Microscopic hematuria is not reliable evidence of bacterial infection. No proteinuria does not rule out urinary tract infections. Most patients with urinary tract infections have urinary protein excretion below 2.0g / 24h.

2. Bacterial culture The most common pathogenic bacteria of urinary tract infections are Gram-negative bacilli, E. coli is the first (90%), followed by Pneumococcus pneumoniae and Proteus mirabilis. Significantly, these bacteria are also common in children and rare in adulthood. It has been suggested that prostate secretions may shorten the survival of these bacteria, which may explain the higher incidence of urinary tract infections after prostatectomy in older men.

Many coagulase-negative staphylococci can reproduce in the bladder, which often occurs in elderly patients with urinary catheterization. Coagulase-negative staphylococci are part of the inherent flora of the distal urethra and can enter the bladder through the catheter. Urinary tract infections caused by S. saprophyticus are less common in the elderly. Anaerobic bacteria of the normal vaginal flora occasionally cause urinary tract infections, especially when the structure of the urinary tract is abnormal.

Chronic urinary tract infections, especially those with recurrent pyelonephritis, should consider the role of l-type bacteria. L-type bacteria are bacteria without a solid cell wall. Bacteria can be transformed into l-type bacteria upon contact with substances that damage their surface, such as antibiotics or antibody-complement-lysozyme. The high tension of the renal medulla is conducive to its survival. L-type bacteria have low virulence, and the virulence can return to normal after conversion to normal bacteria. It has been reported that L-type bacteria have been isolated from older people with chronic urinary tract infections.

Urine culture specimens use clean mid-range urine. Urinary catheterization can be used when elderly women have difficulty retaining specimens. Suprapubic aspirate is not suitable for elderly people. When specimens are not cultured immediately after collection, they should be stored in the refrigerator. Urine specimens can proliferate if left at room temperature for more than 2 hours.

The method of bacterial culture is simple to operate with slanted inoculation, and the results are reliable. For patients who are using antibiotics, urine containing a variety of microorganisms, puncture on the pubic bone, diagnostic urethral catheterization, or evaluation of chronic prostatitis, the urine culture of conventional methods should be used. The automatic screening method is not reliable. The choice of medium is suitable for the growth of all urinary tract pathogens. Better laboratories can check slow-growing co2-dependent bacteria and anaerobic bacteria.

Urinary system infections in the elderly Other urinary system infections

Imaging techniques (including excretory urography and gallium scans) can help older people with urinary tract infections.

Diagnosis of urinary system infection in the elderly

The test methods and diagnostic procedures that can be used for elderly uti are the same as for adults. However, the following points are worth noting:

1. The clinical manifestations of leukocyte urine and bacteriuria or uti are not parallel in the elderly. Some patients with uti may have no leukocyte urine, and some patients may have leukocyte urine due to prostate disease or genital tract mucosal disease without uti. The test can only be used as a secondary diagnostic condition.

2. Most of the elderly show asymptomatic bacteriuria. Effective bacteriological examination is the key to the diagnosis of uti, but urinary tract obstruction, urinary incontinence or frequent urination, long-term use of antibiotics, and improper specimen retention can often affect the results of bacteriological examination. Care should be taken to exclude. It has been reported that penile-coated tube retention urine can be used in elderly male patients with incontinence, which is simple and easy. For those who have repeatedly negative urine culture but still suspected of having upper urinary tract infection, 50% of the urine culture can be detected by urine retention culture after passing the bladder catheter through the bladder catheter after drinking water and diuresis multiple times (every 10 to 15 minutes within 2 hours). Left and right patients have bacteria from the urinary tract. Elderly UTI patients emphasize multiple consecutive bacterial cultures and follow-up observations during the treatment process. Special cultures when necessary can increase the detection rate.

3. Special examinations Due to the presence of urinary tract obstruction factors in the elderly, UTI is difficult to treat and easy to relapse. Therefore, relevant urology examinations and B-mode ultrasound examinations should be performed routinely for elderly UTIs.

Differential diagnosis of urinary system infection in the elderly

Clinically, it must be distinguished from pyelonephritis and cystitis.

Urinary system infections in the elderly Treatment of urinary system infections in the elderly

In the treatment of elderly uti, we should first pay attention to treating basic diseases, remove obstruction factors, and encourage patients to drink more water. Sufficient hydration can dilute local bacteria, flush mucous membranes, and reduce hypertonic state of renal medulla. Local use of a small amount of estrogen in elderly women with urethritis may be beneficial for restoring the physiological state of the lower urinary tract.

It is generally believed that patients with bacterial urine for the first time should be given a single course of antibiotic treatment, with or without symptoms. Most studies have found that as the recurrence rate and reinfection rate of uti in the elderly is extremely high, Long-term maintenance of antibiotics is unnecessary and does not reduce its relapse rate or mortality. It has been suggested that older patients with UTI should be given more aggressive treatment only when early bladder infections, accompanied by progressive renal impairment, and symptoms of upper urinary tract infections are present. The medication should be adjusted according to the urine culture and drug sensitivity test at any time during the treatment process. The elderly uti patients should pay attention to the existence of drug-resistant strains or special pathogens when it is difficult to cure.

At present, it is generally believed that long-term bacteriuria does have an impact on renal function, but there is no certain opinion on the relationship between mortality and uremia.

Prognosis of urinary system infection in the elderly

There is no fully consistent conclusion regarding the impact of UTI on prognosis. Some people think that the mortality of asymptomatic bacteriuria did not change significantly, but when dontas observed the 10-year survival of 342 elderly people, they found that the average life expectancy of 76 patients with bacteriuria was significantly lower than that of those without infection.

Urinary system infection in the elderly

Ideal antibiotics should be selected for urinary tract infections in the elderly: Good antibacterial effect, not easy to make bacteria resistant; Drugs have high concentrations in kidney tissue, urine dregs and blood; Small side effects, no damage to the kidney ; easy to absorb orally; cheap.