Quantitative urinalysis. Diagnosing urinary tract infection in men

Using a hemocytometer, we determined the number of white blood cells (WBCs) per milliliter in uncentrifuged urine specimens. Uninfected urine usually contained less than or equal to 10(3) WBCs per milliliter, although up to 8 X 10(3) WBCs per milliliter were observed. Infected urine regularly contained greater than 10(4) WBCs per milliliter, and the mean WBC count per millimeter for urine from infected patients was 3.1 X 10(5). The absence of pyuria thus provides strong evidence against the presence of urinary tract infection. Similar results were obtained in patients who had indwelling catheters, suggesting that bacteriuria reflects the presence of infection rather than colonization. Valid data are easily obtainable by quantitative urinalysis of uncentrifuged urine specimens. There are obvious differences in WBCs per milliliter, with little overlap between infected and uninfected urine. This method of analysis should replace traditional means of counting WBCs per visual field in a centrifuged, resuspended urine sediment.     

When parents demand "everything"

Patients with end-stage renal disease on hemodialysis have documented defects in their immune responses, and infections contribute significantly to their morbidity and mortality. This study prospectively detected and quantitated leukocyturia and bacteriuria in asymptomatic hemodialysis patients. Thirty-one percent of asymptomatic hemodialysis patients had significant pyuria (> 10 white blood cells per high-power field) and 25% had bacteriuria of pathologic dimensions, (> 1 x 10(5)/mL of a single microorganism). Pyuria was a good marker for significant bacteriuria in these patients. These results demonstrate that the urinary tract, even in ESRD patients on hemodialysis, may represent a significant reservoir for infection.     

Urinary incontinence and bacteriuria in women

We analyzed the urodynamic data and their relationship with significant bacteriuria in 103 consecutive female patients (mean age = 55.7 yrs) with urinary incontinence. Significant bacteriuria was observed in 25.2% of the cases. E. coli was the pathogen most frequently isolated (70.3%). Significant bacteriuria was demonstrated in 29.3% of the patients with urge-incontinence. The most frequent type of incontinence in patients with bacteriuria was no urodynamic reproduction of urinary incontinence (42.8%). Bladder instability was not associated with significant bacteriuria (27.2%). Significant bacteriuria was observed in 75% of the patients with lower urinary tract obstruction, 66.6% of the patients who voided by abdominal straining and 26.3% of those with postvoiding residual urine. These findings indicate that urine culture should be done in patients with no urodynamic reproduction of urinary incontinence. There was no statistically significant correlation between urge-incontinence/bladder instability and significant bacteriuria. Consequently, antibiotics should not be used routinely in female urinary incontinence.     

Does the use of antibiotics in animals affect human health?

This study examined the prevalence of bacteriuria in early postpartum period after term vaginal delivery in Trinidad, West Indies. Asymptomatic bacteriuria occurred in 58 (34.5%) of 168 patients tested. The prevalence of bacteriuria was significantly higher in non-catheterized patients than in catheterized patients and occurred more commonly in patients who were 20 to 29 years old and who were primigravida rather than multigravida. Forty-four patients had a history of urinary tract infection; 18 (40.9%) of these patients had positive urine cultures. Although 10 patients had a vaginal discharge in the late third trimester, none presented with postpartum bacteriuria. Because of the high prevalence of postpartum bacteriuria and the potential to progress to pyelonephritis and chronic renal disease, quantitative urine cultures for all postnatal patients and curative treatment for all positive cultures are recommend.     

Evaluation of an adenosine 5'-triphosphate assay as a screening method to detect significant bacteriuria

The bioluminescent reaction of adenosine 5'-triphosphate (ATP) with luciferin and luciferase has been used in conjunction with a sensitive photometer (Lab-Line's ATP photometer) to detect significant bacteriuria in urine. This rapid method of screening urine specimens for bacteriuria was evaluated by using 348 urine specimens submitted to the clinical microbiology laboratory at the University of Minnesota Hospitals for routine culture using the calibrated loop-streak plate method. There was 89.4% agreement between the culture method and the ATP assay, with 7.0% false positive and 27.0% false negative results from the ATP assay using 10(5) organisms/ml of urine or greater as positive for significant bacteriuria and less than 10(5) organisms/ml as negative for significant bacteriuria.     

Urodynamic factors influence the duration of Escherichia coli bacteriuria in deliberately colonized cases

PURPOSE: We evaluated the influence of urodynamic factors on the establishment of bacteriuria, after deliberate intravesical inoculation with Escherichia coli. MATERIALS AND METHODS: Nine women and 7 men with recurrent symptomatic urinary tract infections underwent intravesical injection of E. coli 83972. This strain had documented ability to persist in the urinary tract and it lacks expressed virulence factors associated with urinary tract infection. RESULTS: Successful long-term colonization (5 months to 3 years) was achieved in 6 of 12 patients with neurogenic bladder disorder, including normal or high bladder capacity, normal or low detrusor pressure and residual urine. Short-term bacteriuria (13 days) occurred in 1 but long-term bacteriuria was not established in the 4 patients with normal lower urinary tract function. Occasionally urine samples from the colonized patients contained other bacterial strains, which cleared spontaneously except for a Klebsiella strain that became established in 2 and subsequently eliminated E. coli 83972. CONCLUSIONS: E. coli 83972 bacteriuria could only be established in a subset of patients with defective bladder voiding, suggesting that urodynamic defects permit a nonvirulent strain to establish in the urinary tract, but that additional host factors determine if bacteriuria will persist.     

Antimicrobial prophylaxis for catheter-associated bacteriuria

We evaluated short-term systemic antimicrobial prophylaxis for catheter-associated bacteriuria in women undergoing elective gynecological operations in a prospective, controlled, double-masked study. Nine of 100 placebo-treated patients acquired bacteriuria during catheterization compared with 3 of 96 of the drug-treated group. However, at the time of hospital discharge, clean-voided urine specimens were positive as frequently in the drug-treated group (8 of 82 patients cultured) as in the placebo group (8 of 75 patients cultured). No difference in febrile morbidity due to bacteriuria was noted between the prophylaxis and placebo groups. The incidence of catheter-associated bacteriuria may be reduced by antimicrobial prophylaxis. However, because the protective effect is transient and is associated with the selection of resistant organisms, prophylaxis is not indicated for patients at low risk for acquired bacteriuria and in whom the sequelae of catheter-associated infections are infrequent.     

Human herpesvirus-6 (HHV-6): current status

Bacteria isolated from the urine of 142 patients with chronic pyelonephritis (CPN) were examined for pathogenic properties of the strains (bacteriuria, hemolytic, proteolytic properties, urease, adhesive activity, antibiotic resistance, the ability to inactivate bactericidal activity of the serum) to control the effect of the treatment: antibiotics combined with plasmapheresis or antibiotics combined with laser radiation (intravascular, transcutaneous, or both). Combined application of intravascular and transcutaneous laser irradiation in multimodality treatment reduces the number of highly pathogenic strains as well as antibactericidal activity of the urine strains. It also promotes normalization of bacteriuria level. Plasmapheresis is inferior to laser radiation but ranks the second in efficacy of action on urinary microflora. Thus, use of efferent methods, especially transcutaneous plus intravascular laser radiation, plasmapheresis, in combined treatment of pyelonephritis decreases pathogenicity of urine strains and normalizes bacteriuria.     

Methodology--a factor analysis of visual evoked responses

Transurethral prostatectomy was performed on 237 patients who required no preoperative antimicrobial therapy and on 182 patients with symptoms of urinary tract infection who received preoperative antimicrobial therapy. At operation all patients were asymptomatic. Data are presented on the incidence of infected prostates, bacteriuria at operation, and postoperative morbidity for the two groups. The findings refute the concept that the chronically infected prostate is resistant to antimicrobial therapy. Transurethral prostatectomy in an infected field was found to increase morbidity. The data suggest that an appropriate preoperative antimicrobial regimen be administered to patients undergoing transurethral prostatectomy with asymptomatic bacteriuria.     

Evaluation of reagent strips in detecting asymptomatic bacteriuria in early pregnancy: prospective case series

OBJECTIVE: To evaluate the performance of reagent test strips in screening pregnant women for asymptomatic bacteriuria at their first visit to an antenatal clinic. DESIGN: Prospective case series. SETTING: Antenatal clinic of a large inner city maternity hospital. SUBJECTS: All women attending for their first antenatal clinic. Patients taking antibiotics for any reason and those with urinary tract symptoms were excluded. INTERVENTION: A midstream urine specimen was divided; half was sent for microscopy and formal bacteriological culture and the other half was tested with a commercial reagent strip test for the presence of blood, protein, nitrite, and leucocyte esterase. MAIN OUTCOME MEASURES: Sensitivity, specificity, and positive and negative predictive values of the reagent strips in diagnosing asymptomatic bacteriuria (defined as 10(5) colony forming units/ml urine). RESULTS: Sensitivity was low, with a maximum of 33% when all four tests were used in combination. Specificity was high, with typical values of 99% or more. Positive predictive value reached a maximum of 69% and negative predictive value was typically 95% or more. CONCLUSION: Urine reagent strips are not sufficiently sensitive to be of use in the screening for asymptomatic bacteriuria and therefore many patients would be missed. In view of the potentially serious sequelae of this condition in pregnant women we recommend that formal bacteriological investigation remain the investigation of choice in this group of patients.     

Clinical evaluation of nitrite test for the detection of bacteriuria

A nitrite test for bacteriuria was compared with routine microscopic examination in 1,318 clinical urine specimens and with bacterial culture in 132. Sensitivity, specificity, positive predictive value and accuracy rate are as follows; for diagnosis of bacteriuria more than 10(4) CFU/ml, 53.4%, 88.6%, 90.4 and 65.2%, respectively; for more than 10(5) CFU/ml, 55.4%, 87.8%, 88.4% and 67.2%, respectively. The positive rate for the nitrite test was 21.4% for bacteriuria of > or = 10(4) CFU/ml in gram positive cocci and 56.9% in gram negative rods. False negative results were obtained from gram positive cocci without nitrate reductive activity or from patients with acute uncomplicated cystitis because of insufficient incubation time in urinary tract. However, this simple test is valuable in the detection of bacteriuria in clinical practice with high specificity.     

Bacteriuria and colonization of double-pigtail ureteral stents: long-term experience with 237 patients

We prospectively studied 266 patients with indwelling double-pigtail ureteral stents to determine the incidence of stent colonization and associated bacteriuria. A urine culture was obtained just prior to stent insertion and was repeated at the time of its removal. The stent itself was also cultured. Of the 237 evaluable patients, 71 (29.9%) developed bacteriuria. Of the 237 stents, 161 (67.9%) became colonized with microorganisms. Pseudomonas aeruginosa was the most common pathogen isolated from the urine and the stents. Stents in female patients had a higher rate of colonization than those used in males (74.4% v 66.5%). The longer the duration of stenting, the higher was the rate of colonization (58.6% for stents left for < 1 month v 75.1% for those left for > 3 months). The rate of colonization according to catheter type was as follows: C-flex 55.5%, silicone 62.6%, urethane 100%, and Urosoft 56%. Long-term ureteric stenting is associated with a high rate of bacteriuria and stent colonization. The duration of stenting and the type of stent influence the results. We recommend that patients with double-J ureteral stents who could be at risk from bacteremia be covered by appropriate antibiotics, and the stents should be kept indwelling for the shortest possible time. If a patient with a stent develops symptomatic infection, an antibiotic should be started that covers the Pseudomonas species.     

The prevalence of asymptomatic urinary-tract infection in pre-school children

Urine samples from 1000 pre-school children aged 4 weeks to 5 years, attending welfare centres, nursery schools or day nurseries in one London borough, were cultured by the dip-slide method. Five children had asymptomatic bacteriuria, a prevalence of 0-5 per cent. The need for screening the urine of pre-school children is discussed.     

Tuberculosis transmission in a high school choir

OBJECTIVE: The prevalence of antimicrobial resistance in urinary pathogens is increasing worldwide. Accurate bacteriologic records of culture results may provide guidance on empirical therapy before sensitivity patterns are available. We report the changing antibiograms of pathogens associated with urinary tract infections (UTI) over a 4-year period at a newly commissioned hospital complex diagnostic laboratory in Trinidad. METHODS: From January 1992 to December 1995, kept records of antibiograms of all urinary pathogens isolated were examined. Samples were derived from hospital sources (wards and out-patient clinics) and general practice sources (health centers and general practitioners). Quantitative bacteriologic cultures were performed according to standard laboratory procedures, and identification of isolates were based on Gram reaction, morphology and biochemical characteristics. Significant bacteriuria was defined as the presence of greater than 100,000 organisms per mL of a midstream urine specimen or more than 3000 bacteria per mL in a catheter specimen of a single specie. Antimicrobial sensitivities were done using the following antibiotics: norfloxacin, ampicillin, tetracycline, nitrofurantoin, gentamicin, co-trimoxazole (sulfamethoxazole-trimethoprim), trimethoprim, nalidixic acid, cephalexin and augmentin (amoxicillin-clavulanic acid). Control organism was E coli NCTC 10,418 strain. RESULTS: The total number of specimens for the 4-year period in hospital was 14,181 with an isolation rate of 17%, and a general practice isolation rate of 67% from a total of 5,088 specimens. E coli was the most frequent isolate in both hospital (40%) and general practice (30%). There was an increase isolation of P aeruginosa from community practice reflecting an increase in home care catheterised male patients. Resistance to tetracycline was most significant in hospital (99%) and general practice (81%). Similar trend was observed for trimethoprim in hospital, and co-trimoxazole in both practices. Resistance to ampicillin, augmentin and cephalexin was relatively stable over the 4-year period. CONCLUSION: We conclude that laboratories should encourage accurate bacteriologic record keeping of urinary isolates and their antibiograms to serve as guidance in empirical treatment in UTI. Also, urine microscopy may reduce the number of specimens sent for culture which are not cost-effective.     

Simplified technique for detection of significant bacteriuria by microscopic examination of urine

A comparative study of microscopic examination of 10 microl (simplified loop technique) and 50 microl (traditional drop technique) of uncentrifuged Gram-stained urine specimens for detection of significant bacteriuria was carried out. The results demonstrated that the 10-microl loop technique can be used as an alternative to the 50-microl drop technique for presumptive diagnosis of urinary-tract infection in bacteriological practice, with the advantages of greater rapidity and ease of performance.     

Urinary creatinine excretion in the ICU: low excretion does not mean inadequate collection

BACKGROUND: It has been assumed that a urinary creatinine excretion rate of less than 10 mg/kg per day means an inadequately collected urine sample. OBJECTIVE: To determine the frequency of a urinary creatinine excretion rate of less than 10 mg/kg per day in intensive care unit patients with an adequately collected urine sample. METHOD: In a prospective study of creatinine excretion rates, 24-hour urine samples were evaluated for urinary creatinine in 209 critically ill patients with indwelling Foley catheters. Patients from three adult intensive care units in New York City were divided into two groups. Group 1 patients excreted less than 10 mg/kg per day of urinary creatinine, and group 2 patients excreted at least 10 mg/kg per day. Groups 1 and 2 were first evaluated by dividing the creatinine excretion data by actual body weight. Since actual body weight may overestimate body weight in the critically ill patient, data from groups 1 and 2 were also evaluated using lean body weight. RESULTS: Urinary creatinine excretion was less than 10 mg/kg per day in 36.8% of patients using actual body weight and 29.7% of patients adjusted for lean body weight. The average age of patients in group 1 was 74 +/- 17 years for both actual body weight and lean body weight. The average age of group 2 patients was 60 +/- 19 years for actual body weight and 62 +/- 19 years for lean body weight. There was a significant difference in age between group 1 and group 2 patients for both actual body weight and lean body weight. The proportion of female vs male patients with reduced creatinine excretion was significantly greater, whether the actual body weight or lean body weight adjustment was used. CONCLUSIONS: A urinary creatinine excretion rate of less than 10 mg/kg per day occurs in about one third of critically ill patients, who are more likely to be elderly and female.     

A simple and efficient urine sampling method for bacteriological examination in elderly women

AIM: to determine how collecting urine voided directly into a container compares with urine obtained by suprapubic aspiration. METHOD: urine samples were collected in a sterile recipient placed in the toilet or in the bed-pan during voiding, after the vulval region had been cleaned by water. These samples were compared with samples of the same urine obtained by suprapubic aspiration. The samples were examined for pyuria and bacteriuria. Applying the Kass criteria on the voided urine specimen and assessing the presence of leucocyturia, it was possible to differentiate urinary tract infection, asymptomatic bacteriuria and contamination. RESULTS: all 13 cases of infection found on suprapubic aspiration were also identified by this sampling technique. The technique produced four false-positive results. CONCLUSION: this simple sampling method may not only obviate the need for suprapubic aspiration but also for bladder catheterization in the diagnosis of urinary tract infection in many elderly women.     

新型2Cr1Mo2Ni钢在含二氧化碳油田采出液中的腐蚀行为

为弄清Mo和Ni元素在低Cr钢耐蚀方面所起的作用,炼制了新型2Cr1Mo2Ni钢,研究其在模拟油田采出液中的腐蚀行为,实验条件为80℃,0.8 MPa CO₂分压.利用扫描电镜和能谱分析研究了2Cr1Mo2Ni钢和3Cr钢的腐蚀产物膜微观形貌和成分,测试了高温高压极化曲线和电化学阻抗谱,分析了腐蚀产物膜的生长过程.实验结果表明,Mo和Ni元素在提高抗CO₂腐蚀性能方面的作用不及Cr元素.2Cr1Mo2Ni钢腐蚀164 h后,中低频感抗弧消失,腐蚀产物膜开始完全覆盖基体表面;腐蚀240 h后,生成的腐蚀产物膜具有较好的保护性.      

Basal nitric oxide synthesis in essential hypertension

BACKGROUND: There is indirect evidence that nitric oxide (NO) synthesis in vascular endothelium of patients with hypertension is altered. The aim of this study was to estimate more directly NO production in patients with untreated essential hypertension by measurement of synthesis of inorganic nitrate, which is the end product of NO oxidation in humans. Two separate studies were undertaken in patients with hypertension and appropriate healthy controls. METHODS: In the first study, ten patients and 13 controls were given a diet containing 82 mumoles nitrate per day for 2 days, with urinary and plasma nitrate measurement and 24 h ambulatory blood pressure monitoring on the 2nd day. In the second study, 11 patients and 11 controls were studied in the postabsorptive state; a bolus of 200 mg L[15N]2 arginine was administered intravenously over 10 min. 24 h ambulatory blood pressure monitoring was done and complete urine collections were made for the next 36 h. FINDINGS: In the first study, 24 h urinary nitrate excretion was lower in the hypertensive patients than in the control group (mean 450 [SEM 37] vs 760 mumoles [77] per 24 h; p < 0.001). There was an inverse correlation between average mean daytime ambulatory blood pressure and nitrate excretion (p = 0.007; r2 = -0.73). In the second study, mean 36 h urinary 15N nitrate excretion was significantly lower in the hypertensive than in the control group (1313 [50] vs 2133 [142] pmoles; p < 0.001). There was an inverse correlation also between average mean daytime ambulatory blood pressure and 24 h urinary 15N nitrate excretion expressed per mmole of creatinine (p = 0.002, r2 = -0.59). In addition, total urinary 15N nitrate excretion in the hypertensive group was significantly higher in women than in men (285 [16] vs 198 [14] micrograms 15N nitrate per kg; p = 0.026). INTERPRETATION: These data suggest that whole-body NO production in patients with essential hypertension is diminished under basal conditions. The origin of the NO we measured is not known, and we cannot tell whether the impaired synthesis is primary or secondary to a rise in blood pressure.     

Abnormal hypothalamic-pituitary-adrenal axis function in rheumatoid arthritis. Effects of nonsteroidal antiinflammatory drugs and water immersion

OBJECTIVE: To investigate the effects of nonsteroidal antiinflammatory drug (NSAID) therapy and water immersion on hypothalamic-pituitary-adrenal (HPA) axis function in rheumatoid arthritis (RA). METHODS: Plasma levels of adrenocorticotropic hormone (ACTH) and serum and urine levels of cortisol were compared in untreated RA patients, NSAID-treated RA patients, and healthy control subjects. RESULTS: ACTH levels were significantly higher in untreated RA patients (mean +/- SEM integrated area 11,377 +/- 5,246 hours ng/liter) than in NSAID-treated RA patients (2,285 +/- 388 hours ng/liter) or healthy controls (1,845 +/- 35.5 hours ng/liter) (P < 0.001). Serum and urine cortisol levels were not significantly different between groups. Two-hour head-out water immersion had no effect. CONCLUSION: Elevated ACTH levels without hypercortisolemia occur in untreated RA. NSAID therapy alters HPA axis response, but immersion has no effect.