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Urinary tract infection related check

Laboratory tests Routine examination of urine routine is the easiest and most reliable way to diagnose urinary tract infections. For the first time in the morning, there are five (, 5 / HP) white blood cells called suppurate. Acute urinary...

Urinary tract infection related check

Jun 06, 2017 by Kidney Disease Expert

Laboratory tests

Routine examination of urine routine is the easiest and most reliable way to diagnose urinary tract infections. For the first time in the morning, there are five (>, 5 / HP) white blood cells called suppurate. Acute urinary tract infection, besides have pyuria, often can be found that white tube type, bacteriuria can sometimes with microscopic haematuria or visible to the naked eye hematuria, especially in bloom bacillus, slave card bacteria, actinomyces, mycobacterium tuberculosis infection. Occasionally, the microalbuminuria, if there is more proteinuria, indicates that the glomeruli is tired.

It is worth noting that urination does not mean that there must be an infection in the urinary tract because it can be pided into septic and aseptic urination. Aseptic pus can be seen in various small tubular interstitial nephritis. Tubular interstitial nephritis causes extensive, common diseases are reactive tubular interstitial nephritis (that is, the system caused by tubular interstitial nephritis), allergic tubular interstitial nephritis (many medications can cause), nonsteroidal anti-inflammatory drugs related to kidney disease, heavy metal toxic nephropathy, radioactive nephritis, reflux nephropathy and various kinds of idiopathic tubular interstitial nephritis.

The urine bacteria culture used to believe that the clinical significance of the ">, 000 / ml" of the amount of bacteria that was used to produce the bacteria in the clean middle section was "the result of pollution". Existing a large number of facts prove that, although about 92% of urinary tract infections caused by gram-negative bacteria colony count > 100000 / ml, but only about 70% of gram-positive bacteria of urinary tract infection caused by colony count more than 100000 / ml, and 20% ~ 30% of the patients the colony count only 1000 ~ 100000 / ml, especially under the most urinary tract infections. The reasons for the low count of colonies are:

(1) the amount of time spent in the bladder in the bladder is too short to allow the bacteria to reproduce.

(2) treatment with antibiotics.
(3)The use of diuretics makes it difficult for bacteria to grow and reproduce.

(4) Acid urine is bad for the growth of bacteria.

(5) there is a urinary tract obstruction (such as stone and infection), and the urinary tract is restricted.

(6) external infection.

(7) the pathogen is anaerobic and cannot be grown by conventional culture.

(8) the gram-positive bacteria were slow and concentrated, and the colony count tended to be low.

As a result, clinical symptoms are consistent with urinary tract infections, and urinary tract infections are also considered when the urinary colony count is 1000 ~ 100,000 / ml.

The method of chemical testing of bacteriuria has been used in the past to develop the test of bacteria positive and microscopy for the presence of urinary tract infection as a standard for diagnosing urinary tract infections. But given the prevalence of UTI in all age groups, and the emphasis on family or outpatient diagnosis and treatment of UTI. There are four methods available for rapid diagnosis of bacteriuria.

(1) nitrate reduction: the most commonly used yet is the Griess nitrate reduction method. The test is the most accurate for the first urine in the morning and can be quite accurate in determining whether the infection was caused by e. coli. But it could not be used to detect infections caused by gram-positive bacteria and pseudomonas. Due to the time spent in the bladder in the bladder, it is necessary to reduce the nitrate of the bacteria, and the result is a false-negative result in the absence of a certain amount of nitrate or diuresis in the diet.

Application of combined nitrate method and professional cheap paper, white blood cells ester enzymatic within 2 min can be obtained as a result, thus greatly improves the practical value of this method. This method has diagnostic value of more than 100, 000 / ml of escherichia coli in urine or urination, and the expected value of its negative test results is 97%. False-negative results can be found in proteinuria and urine with the presence of gentamicin or cephamycin. The sensitivity of the trial was reported to be 87%. Specificity is 67% (false positives are usually caused by vaginal contamination). (1) This method is more effective in screening patients with symptomatic urine than screening for asymptomatic patients.

(2) triphenyltetrazoliazole test: this test results in false-positive results when the pH value of a large amount of vitamin C or urine is < 6.5. False-negative results can occur if the reagent is caused by streptococcus, certain enterococcus and pseudomonas.

(3) the method of glucose oxidase and peroxidase test: glucose oxidase method is the principle of the bacteria can consume exist in people without diabetes a small amount of glucose in urine, the principle of peroxidase test is most urinary bacterial pathogens are the enzymes, inflammatory cells in any disease also have this enzyme. The accuracy of these two methods is much worse than the two methods.

(4) slide-slip method: this method is to AGAR coated on the surface of plastic plate, and the tablet into the urine, drip dry urine after incubation, usually will have a choice of gram-negative bacteria effect of AGAR onto the tablet or the side of the glass, and for most bacteria including gram-positive bacterium growth without AGAR selection effect on the other side of the flat glass or, after a night of incubation, many colonies appear in both the AGAR surface on both sides, it can be compared with standard colony map, can be half quantitative estimates the number of bacteria in the urine. Positive films can also be tested for bacterial and drug susceptibility. This technique is often used in outpatient or domestic screening.

(5) semi-automatic methods: three semi-automatic methods can be used for the diagnosis of UTI.

(Bac - T - Screen method: this method is to urine specimen by the filters, dyeing, washing, and then using the colorimetric colorimeter, this technique can detect 10000 / ml bacteria in urine. Sensitivity is about 88%, but specificity is only 66%. Its disadvantages are the ability to block the instrument or affect its specificity because of the presence of other colored particles in urine.

(2) the bioluminescent method: bacteria to produce ATP, can use a firefly luciferin/luciferase bioluminescent reactions to test, with the amount of bacteria ATP to reflect the number of bacteria. This method can check the threshold number of bacteria in urine is 10000 / ml, the sensitivity is about 97%, specificity of 70% ~ 80%, the most valuable in patients with negatie urine test bacteria. The negative expectation value of this method is greater than 99%.

Electronic impedance particle counting: this is a method that does not rely on the proliferation of bacteria, which can detect white blood cells separately. Although this method currently has a high false-positive rate (20% ~ 25%), it is still a promising detection technique.

The location of the infection was similar to the clinical manifestations of the upper and lower urinary tract infection, but there was a significant difference in the response to the treatment and the type of the pathogen. The bladder infection is an infection of superficial mucosal in the anatomical location, and the antibiotic can easily reach high concentrations in the area. In contrast, a kidney infection (male prostate infection) is an infection of a deep tissue. As a result of the biological and biochemical environment, the natural defenses of this tissue are weakened, and the concentration of antibiotics to reach the site is limited. The types of antibiotics needed to treat urinary tract infection vary depending on the location of the urinary tract infection. In contrast to bladder infections, kidney infections (and prostate infections) require a more powerful or prolonged antibiotic treatment.

Since 30 to 50% of the clinical symptoms of patients with concealed kidney infection are mainly due to the following urinary tract, it is not possible to locate the diagnosis based on clinical performance alone. There are several ways to locate a urinary tract infection:

(1) bilateral ureteral intubation: bilateral ureteral intubation is the only direct method to the diagnosis of infection to locate, although its damage is bigger, but compared with all other infection localization diagnosis methods, is still the most accurate.

(2) bladder irrigation after flushing: a less damaging method is bladder irrigation after flushing. The main drawback of this approach is that it can't tell whether the kidney infection is unilateral or bilateral. Compared with all non-invasive methods, however, it is easy to operate, safe, cheap and without cystoscope professional help, it has instead of ureteral intubation in the localization diagnosis of infection.

This approach involves inserting a catheter into the bladder and taking urine for the size 0 specimen. Then use 100 ml saline in antibiotics (usually with neomycin or neomycin slime molds element) rinse bladder, with a 200 ml saline rinse bladder, emptying after collecting the last a few drops of urine specimen 1; Specimens from 2 to 5 are collected every 15 minutes. Samples from 0 to 5 were cultured and the results were as follows:

The number of specimens in the specimen number 0 was >, 100, 000 / ml, indicating the presence of bacterial urine.

Samples 1 ~ 5 were aseptic, indicating the infection of the urinary tract.

The number of specimens from the 2 ~ 5 specimen was 10 times greater than the number of specimens from the number 1 specimen, and was shown to be infected with urinary tract infection.

(3) the determination of urine enrichment function: the function of the renal medulla is evaluated by the measurement of the maximum urine concentration function, which can be used to distinguish the infection of the kidney and bladder. The infection of the renal medullary area can change the maximum urine concentration function. The inflammation of the small and acute renal tubules often leads to a decrease in the function of urination, so the maximum urine concentration function can be applied to the optimal evaluation. Pyelonephritis in urine concentration function impairment is related to inflammation of the renal medulla department is caused by a metabolic disorder of prostaglandins, because it can by giving the prostate synthetase inhibitors - indomethacin blocks. Studies have confirmed renal bacteriuria is related to the concentration of urinary function decline, while the bladder bacteriuria has nothing to do with it, and bilateral renal patients decreased function of urine concentration significantly greater than unilateral kidney infections. In patients with unilateral renal infection, they may be shown to have impaired lateral urination, while unimpaired lateral urination is normal. The recovery of urine concentration function is related to the eradication of infection. The disadvantage of this approach is that there is a cross-overlap between bladder infection, unilateral kidney and bilateral kidney infection. Therefore, this method is not listed as a routine check because of its sensitivity difference.

(4) urinary enzyme detection: urinary enzyme examination can reflect the small tube inflammatory lesions, and the infection of renal medulla area can appear renal medulla inflammation, urinary enzyme increased consequently.

Pyelonephritis patients experienced a 25% rate of lactate dehydrogenase (LDH) activity increased, but a false negatie result, and also can appear when hematuria and severe proteinuria false positive results. The urine of patients with pyelonephritis has been found. Beta-glucuronidase activity is significantly higher than in the lower urinary tract. In the kidney, the beta-glucuronidase activity is slightly higher than the bladder infection. However, since this enzyme activity has considerable overlap in these patients, this approach is not a diagnostic value for every patient. The n-acetyl-beta-d-glucoaminase (NAG enzyme), which measures renal tubule cells, also can be used to locate the infection and find it promising. Pyelonephritis (906 + 236) for the patients with urinary creatinine level mol/(h. mg), and urinary tract infection, urinary creatinine level (145-23) mol/h. (mg) and normal children urine creatinine is (151.6 + / - 10) mol/(h. mg). The urinary NAG enzyme decreased when the treatment of the children's pyelonephritis was effective. Unfortunately, other studies have found a significant overlap between pyelonephritis and urinary NAG.

So while detecting urine enzyme or antigen, renal tubule cells for UTI anatomic localization diagnosis of promising, but the infection to locate the best detection method still need further discussion.

(5) c-reactive protein detection: application reports that immune diffusion technology to detect serum c-reactive protein, found that children with pyelonephritis c-reactive protein levels continue to rise, while the level of c-reactive protein in patients with acute cystitis is normal. Changes in the level of c-reactive protein in patients with pyelonephritis can be used as an indicator of efficacy. But the diagnosis was inconsistent with the diagnosis of bladder flushing. Due to the various other inflammatory conditions, can also be elevated c-reactive protein level, so there will be false positives, and the quantity of c-reactive protein and no correlation between the infection. According to our experience, this method is more sensitive to the localization of adult urinary tract infection.

(6) bacterial antibody detection: kidney infections often accompanied by directly against pathogens antigen specific antibody, the synthesis of many researchers tried to application of immunology technology to solve the problem of UTI anatomical localization diagnosis. Application of bacterial adhesion test found that patients with symptoms of acute pyelonephritis in the serum antibody levels rise, and the drop degree as the effectiveness of the response to antibiotic treatment. The serum antibody levels were also elevated in patients with no apparent symptoms of pyelonephritis, and the serum antibody drops were normal in patients with cystitis. Researchers using ureteral intubation lectin antibody detection of infection to locate studies confirm that kidney infections lectins is significantly higher than the bladder bacteriuria antibody concentration. However, the variation of the antibody titer was larger, and there was considerable overlap between the two groups. So there is a limit to the diagnostic value of this serological method.

In recent years, the most widely used localization technology is the urine antibody wrap bacteria analysis method (ACB). The immunofluorescence technology has found that the bacteria that originate in the kidneys are tested positive for the antibody package. The bacterial antibody for the urinary tract infection was negative. Although with the further popularization of application of ACB, there have been some problems, but the results get further confirmed by other researchers, the following is about the status of this method makes a comprehensive evaluation:

(1) urine specimens are contaminated with the vagina or rectum flora, appears to be a massive proteinuria, nephrotic syndrome patients and infection involvement outside of the urothelium (prostatitis, hemorrhagic cystitis and bladder tumor or bladder infection caused by intubation), test results can appear false positives.

Between 16 and 38 percent of adults with acute pyelonephritis and most children acute pyelonephritis can have false negative ACB test results. ACB for chronic pyelonephritis is 95 percent accurate. This may be related to the first infection, when the bacteria invades the kidney 10 to 15 days after the infection. In the case of a repeat infection, the ACB test results in a much shorter amount of time due to the presence of an antibody response in the body.

In the case of women with acute single-sex UTI, ACB has a different positive rate of ACB in different patients. These differences may be related to the degree of difficulty and symptoms of the visit and the duration of the treatment.

A group of ACB positive people had a heterogeneity in response to single dose antibiotic therapy. With 50% ~ 60% of the ACB positive effective for the treatment of acute uncomplicated UTI women, for ACB negative acute uncomplicated UTI women, approximately 95% of patients on this treatment is effective.

To summarize, the ACB test is not a routine examination of the diagnosis of urinary tract infection. Therefore, we need to continue to search for better, non-invasive methods of locating UTI.

Imaging examination

Imaging examination for the UTI imaging examination, the main purpose is to determine whether the patient has an abnormality in the urinary tract that requires internal medicine or surgical treatment. This type of examination is particularly beneficial for children and adult male patients. There is more controversy over how to apply these methods appropriately to women.

UTI's basic principle of diagnostic examination:

(1) for suspected obstructive bacterial pyelonephritis hospitalized patients, especially the infection has not responded well to proper treatment line to excrete sex urinary tract imaging or ultrasound examination, rule out the possibility of presence of urinary tract obstruction. While for septic shock to the emergency line above check, if the pressure cannot remove through drainage abscess in these patients obstruction and reduce, the patient usually cannot get effective treatment.

(2) for the first time or again UTI in children, especially the aged < 5 years old, should be at the same time line vein angiography of the renal pelvis and bladder, urinary tract imaging to check whether there is a urinary tract obstruction, the existence of VUR and renal scarring. Sh 2 propanol succinic acid (DMSA) scanning technology can be used to replace vein imaging detecting the presence of scarring of the renal pelvis, but not clear scar is in calyces of the renal pelvis or ureter. These tests can not only identify the patients need surgery, but also can clear which patients of scarring and mild VUR to extend the effective preventive antibiotic treatment. Because active infection can cause VUR itself, it is recommended to be tested for 4 ~ 8 weeks after infection.

The above method is not ideal, the reason is the client has 60% ~ 90% for negative results, and the cost is relatively high, the younger children to radiation and bladder intubation is not appropriate. But there is no other technology can be used in the high risk of urinary tract anatomy abnormality diagnosis of pediatric patients, especially for traumatic infection localization diagnosis technology has little diagnostic value for this group of patients.

(3) most adult male UTI has a urinary tract abnormality, most commonly the obstruction to the neck of the bladder due to prostatic hyperplasia. In the anatomical location and diagnosis, therefore, should first detailed check the prostate, and then consider whether the discharge urinary tract imaging, or urinary tract after emptying of ultrasound, the all men UTI patients should be seriously considered.

(4) for the first time, the majority of women with UTI are considered not to be photoimaging, but there is a lot of controversy about the treatment of the infection. In patients with recurrent UTI women, most scholars in the first place not in favor of the conventional microscopic examination of the bladder, and imaging and urinary examination results found to have abnormal urinary tract structure is only 5.5% ~ 5.5%, and the results of clinical treatment of patients with no significance. Therefore, it is not argued that the traditional anatomical localization diagnosis should be carried out for the women who reissue the UTI. This is not to say that these checks make no sense to some patients. But to choose those with anatomy examination has inspected the indications of women, including those with invalid or soon relapse after treatment, persistent hematuria, urea decomposition bacterial infection, sustained inflammation symptoms such as night sweats, or there may be obstruction symptoms, although give appropriate antimicrobial therapy for low back pain or abdominal pain of patients. It is generally beneficial for the treatment of antibiotics for ineffectual imaging and ultrasonography.

2. Due to acute urinary tract infection is prone to bladder ureter reflux, intravenous or retrograde urography angiography should be after 4 ~ 8 weeks after infection to eliminate, acute pyelonephritis and no complications of recurrent urinary tract infection is not conventional angiography of the renal pelvis. , in patients with chronic or cured respectively as needed for urinary tract plain radiographs, intravenous urography angiography, retrograde urography angiography, emptying bladder after nephroureterectomy and examined for obstruction, stones, ureteral strictures, or compression, nephroptosis, urinary congenital malformation and bladder ureter reflux phenomenon, etc. In addition, the renal pelvis and renal cell form and function can be understood in order to identify with renal tuberculosis and kidney tumor. The renal pelvis of chronic pyelonephritis is slightly expanded or clubbed, with scar malformation. When kidney function is not fully functional, two or three doses of iodine can be injected into the vein, and a multiple shot is needed to make the contrast satisfactory. Renal angiography may indicate that the small blood vessels of chronic pyelonephritis have different degrees of distortion.

3. The nephrogram examination can understand the kidney function, urinary tract obstruction, bladder ureter and urinary bladder residual urine. The kidney diagram of acute pyelonephritis is characterized by the postpeak movement, and the secretion stage appears to be delayed by 0.5 ~ 1.0 min. In chronic pyelonephritis, the slope of the secretion of the pyelonephritis decreases, the peak becomes blunt or widens, and the initial delay of the drainage segment is parabolic. But the changes are not particularly specific.

4. The ultrasound Is currently the most widely used, the most simple method, can detect dysplasia, congenital urinary tract malformation, polycystic kidney, renal artery stenosis caused by kidney size not pide evenly, stones, renal pelvis heavy water, tumor, prostate disease, and so on.


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