Urinary tract infection (UTI) is a general term for microbial infections occurring anywhere in the urinary tract from the urethra to the kidneys.UTI occurs in people of all ages and is the most common cause of sepsis in the elderly. With the gradual increase in human life expectancy, the prevalence of various infectious diseases has increased significantly in the elderly, with the prevalence of UTI ranking second only to respiratory tract infections in the elderly population aged >65 years. Elderly patients are clinically characterized by complex etiology, many influencing factors, atypical symptoms, heavy disease and prolonged disease. In recent years, although antibacterial drugs have been commonly used for treatment and prevention, the recurrence and reinfection rates have not been significantly reduced due to changes in the pathogenic spectrum of causative organisms and the emergence of drug-resistant strains. In particular, it is difficult to prevent and treat patients with complex urinary tract infections such as abnormal urinary tract function, urinary tract obstruction, reflux, and those suffering from systemic immune or metabolic diseases. Therefore, we need to continuously improve the prevention and treatment of urinary tract infections in the elderly.
I. Pathogenic factors of urinary tract infections
1, pathogenic bacteria: any pathogenic bacteria can cause urinary tract infections. According to the literature, the pathogenic bacteria of UTI in the elderly are still mainly Gram-negative bacilli. Community-dwelling older adults with acquired urinary tract infections, 80% are caused by gram-negative bacilli (such as Escherichia coli) and 20% by gram-positive cocci (such as enterococci and penicillin-resistant Staphylococcus aureus). In elderly or hospitalized patients in nursing homes, E. coli remains the most common causative agent; however, Pseudomonas aeruginosa, Enterococcus and Candida, other Enterobacteriaceae, and conditional pathogens are also frequently reported. E. coli infection is more common in older women than men, and is the main pathogen causing urinary tract infections in postmenopausal women.
2, susceptibility factors: diabetes, hypertension, advanced tumor, long-term bed rest, malnutrition, long-term application of antibiotics and immunosuppressants, renal insufficiency with reduced urine volume, urinary tract obstruction and foreign body, are prone to urinary tract infections. For elderly men, if accompanied by dementia, severe prostatic hypertrophy, urinary retention, urinary incontinence, long-term catheter use, and indwelling catheters for cystostomy are the main susceptibility factors causing urinary tract infections in the hospital. According to statistics, even under strict sterilization, urinary tract infection caused by 1 catheter is about 2%; for those with indwelling catheters for more than 4 d, urinary tract infection can be as high as 90%; after 10 d of continuous indwelling catheters, all have urinary tract infection. Older women with a history of UTI before menopause and symptoms such as urinary incontinence, bladder hernia, and urinary retention are more likely to have recurrent urinary tract infections. Postmenopausal uncomplicated urinary tract infections in older women often present as symptomatic or asymptomatic bacteriuria, with a significantly higher frequency of recurrent episodes than in younger women. Because of the significant increase in bladder residual urine after menopause, in addition to the decrease in estrogen secretion after menopause, the vaginal epithelium and urethral mucosa become more susceptible to local pathogens; there are also some urinary tract infections due to the absence of lactobacilli in the vaginal mucosa, which increases the vaginal pH.
Treatment of urinary tract infection
1, reasonable choice of drugs: first of all, the site of infection and causative bacteria should be clarified. The clinical manifestations of urinary tract infection in elderly patients are not typical, so targeted medication should be based on urine culture and drug sensitivity results; secondly, it should be clarified whether it is the first attack or multiple relapses, simple or complex? The second thing should be clarified whether it is the first episode or multiple recurrence, simple or complicated, lower or upper urinary tract infection. Emphasis should be placed on early diagnosis and prevention of secondary systemic infection and bacteraemia. When the urine bacterial culture has not yet come out or the result is negative, antibiotics can be selected according to the antibacterial spectrum of antibiotics. For example, Escherichia coli can choose quinolones, amoxicillin potassium clavulanate, three generations of cephalosporins, cefoperazone/sulbactam, piperacillin/triazobactam, hydrocarbons, cefepime, amikacin, sulfonamides, and antronan, etc.; Pseudomonas aeruginosa can choose ceftazidime, ciprofloxacin, aminoglycosides; Enterococcus spp. The p-lactamase inhibitors can protect the p-lactam antibiotics (penicillins and cephalosporins) from inactivation, thus maintaining their good antibacterial activity, so the application of their compound preparations has received much attention. At present, the commonly used combination of p-lactam antibiotics and p-lactamase inhibitors are: amoxicillin clavulanate potassium, amoxicillin sulbactam, ampicillin a sulbactam (ulexin), cefoperazone a sulbactam (sopressin), hydroxybenzyl penicillin a clavulanic acid (Aventis data Metin), carothiophenol penicillin a clavulanic acid (Temetin) and piperacillin a tazobactam ( tazobactam), etc. These compound preparations compared with single B-lactam antibiotics, has the advantages of good infection control efficacy, high sensitivity to pathogenic bacteria and low minimum inhibitory concentration. Urethral excretory drugs are beneficial to the control of urinary tract infections. Penicillins, cephalosporins and aminoglycosides are mainly excreted by the kidneys, and their urinary drug concentrations are tens to hundreds of times higher than the blood concentration. Macrolides, lincomycin and rifampin can also reach effective concentrations in urine, and chemically synthesized drugs such as sulfonamide, furantoin and norfloxacin can also reach higher concentrations in urine. Different drugs have different antibacterial activity in urine with different pH levels. Aminoglycosides have increased antibacterial activity in alkaline urine and tetracyclines in acidic urine. Therefore, depending on the situation, sodium bicarbonate or vitamin C can be added. alkalinization of urine can reduce the solubility of ciprofloxacin, leading to crystalluria and kidney damage.
2.Dosing methods.
(1), most uncomplicated lower urinary tract infections are currently clinically advocated to implement a 3 d course of treatment. Unlike the traditional treatment course of up to 7-10d, SMZco, amoxicillin, amoxicillin/clavulanic acid, 1st generation oral cephalosporins, fluoroquinolones, doxycycline, etc. are selected.
(2), 7d therapy is indicated for patients with symptom duration greater than 7d, recent history of recurrent urinary tract infection, and age greater than 65 years.
(3), Acute pyelonephritis manifested as low fever, normal or mildly elevated peripheral blood leukocytes, no nausea and vomiting, and mild to moderate infection with good compliance, SMZco, oral cephalosporin, amoxicillin, amoxicillin/clavulanic acid, and fluoroquinolones can be used for a 14d course of therapy.
(4), patients with severe infections showing high fever, significantly elevated peripheral blood leukocytes, vomiting, dehydration or sepsis, and those who have failed outpatient treatment, may use ampicillin or ampicillin/sulbactam, broad-spectrum cephalosporins or anti-pseudomonas penicillins administered by injection, and enterococcal infections with ampicillin or ampicillin/sulbactam + aminoglycosides; for those who are allergic or resistant to penicillin, (desmethyl) Vancomycin, 14d course of treatment.
(5), complex urinary tract infection, the first should be removed as far as possible complex factors, because of complex urinary tract infection pathogenic bacteria with high degree of drug resistance, need to select antibacterial drugs according to bacterial culture and drug sensitivity results, the total course of treatment 14 ~ 21d.
(6), for patients who cannot correct urinary tract abnormalities and should not be operated, infection control can be long-term controlled treatment with small doses of antibacterial drugs.
3, antibiotic dose: the elderly serum creatinine value even in the normal range, its glomerular filtration rate is often lower than the normal 50% or significantly reduced, especially the elderly, long-term bedridden, low activity, muscle atrophy, poor nutrition. Therefore, the application dose and administration interval of antibiotics should be strictly adjusted in accordance with the degree of renal decompensation, i.e. glomerular filtration rate (non-serum creatinine), otherwise elderly patients can not tolerate the toxic side effects of drugs, liver and kidney function damage or 701 flora dysbiosis. Elderly patients should use antibacterial drugs with low toxicity, such as penicillins, sporomycins, p-lactams, quinolones, sulfonamides and other drugs. Nephrotoxic aminoglycosides, glycopeptides (such as vancomycin, desmethylvancomycin) drugs as far as possible to avoid, if it must be used, should be strictly according to the glomerular filtration rate to adjust the dose of drugs.
4. Timing of medication: In 2001, Loeb et al. recommended a series of criteria for when to use antibiotics in elderly UTI patients. For those without indwelling catheters, if there is acute difficulty in urination or fever over 39°C or temperature over 1.5°C of basal body temperature, and one of the following criteria is met: new or worsening urinary frequency and urgency, pain in the pubic arch, carnal hematuria, spinal rib angle pressure pain or urinary or fecal incontinence; for inpatients with indwelling catheters, one of the following manifestations: fever over 39°C or 1.5°C of basal body temperature, sudden spinal Antibiotics may be initiated in patients with indwelling urinary catheters with one of the following manifestations: fever over 39°C or 1.5°C above the basal body temperature, sudden onset of spinal cord pressure, chills and shivering with or without obvious cause, or new onset of mental disturbance. Elderly women with uncomplicated acute pyelonephritis, symptomatic bacteriuria, and infections with deep systemic tissues are all at high risk for bacteremia, and antibiotic therapy should be intensified at this time.
5. Examination and treatment of anatomical and structural abnormalities of the urinary system.
(1) Urinary tract obstruction is often a direct cause of infection. Older people often have severe prostate enlargement, hypertrophy or bladder neck obstruction, as well as urinary stones and tumors, resulting in incomplete or complete obstruction of the urinary tract. refractory infection.
(2) Long-term indwelling catheter is the main factor of UTI in elderly people over 60 years old. Catheters can cause urethral obstruction, male urethral stricture, epididymitis, orchitis and prostatitis. Systemic antibiotics temporarily reduce the bacterial count in the urine of the bladder, but do not eliminate catheter-induced infections. Bacteria form a complex biofilm structure on the surface of the catheter that prevents the antibiotics from acting on it, and once the antibiotics are discontinued will lead to a recurrence of the infection.
III. Prevention of UTI
A longer course of antibiotics is effective in reducing the recurrence of UTI in older women. For older women with 2 infections in 6 months or 3 or more infections in 12 months and who are symptomatic, prophylaxis should be continued until the infection is eradicated. Most experts recommend 1 dose per night for 6 months, and some recommend continued prophylaxis for 2 years. Antibiotics used for prophylaxis include methotrexate and sulfamethoxazole, furantoin, and cephalosporins. Severe prostate enlargement is a risk factor for UTI in older men, and partial prostatectomy can help reduce recurrence of infection. Cranberry juice or capsules prevent E. coli and other gram-negative bacteria from adhering to the host cell surface. Different types of adhesins on the cilia of E. coli or other bacteria can adhere to epithelial cells, and the unique compound component of cranberry, proanthocyanidin, inhibits the adhesion process. Measures to prevent infection of indwelling catheter are currently recognized by most scholars as.
(1), use intravesical indwelling catheters only when absolutely necessary, shorten their retention time as much as possible, and patients with long-term indwelling catheters should be replaced promptly according to the patient’s condition.
(2).Keep the catheter system airtight, and open the system only when an obstruction occurs and flushing is needed.
(3).The urinary bag should be fixed in a position lower than the bladder to prevent urine reflux.
(4), Once infection occurs, the indwelling urinary catheter should be immediately removed or replaced with a new urinary catheter system, while strict disinfection measures should be strengthened and every link should be carefully controlled; if the catheter is indwelling for more than 7d, the urinary catheter should be removed first and then treated with antibiotics.
(5), Patients with indwelling urinary catheters should be separated from those with urinary tract infections, and they should be instructed to wash their hands strictly.
(6).Asymptomatic patients do not need treatment, and symptomatic patients should be given effective antibiotics immediately according to the degree of infection.
(7), Catheters injected with antibiotics may reduce the incidence of asymptomatic bacteriuria within 1 week, but will not reduce symptomatic infections, and therefore are not recommended for routine use.
(8).Urinary catheters with silver alloy can significantly reduce asymptomatic bacteriuria within 1 week, and there is also information that it can reduce the occurrence of symptomatic UTI.
(9) After non-urinary surgery, the catheter should be removed before midnight if possible.