Simple Disposable Method for Quantitative Cultures of Urine

A disposable kit was tested as a means of detecting significant bacteriuria by quantitative culture of urine. The total error in 3,563 specimens tested by five investigators was less than 1%. The method was very effective in differentiating significant bacteriuria, i.e., more than 100,000 bacteria per ml of urine from uninfected urine. In specimens from patients with urinary tract abnormalities who had mixed bacterial flora, the absolute numbers obtained with the dip-inoculum method had a 10% variation when compared to results obtained by calibrated loop or dilution pour plate methods. Therefore, the main utility of the kit is for screening and following patients after therapy. A significant delay in time between inoculation of the medium in the kit with the freshly voided urine and incubation of the kit to promote growth did not affect the reliability of the kit as a method of doing quantitative urine cultures to detect bacteriuria.     

Rapid screening for bacteriuria with a laser nephelometer

Detection of significant bacteriuria with a laser nephelometer was evaluated in this study and compared with the results obtained by the quantitative loop method. We screened 1002 urine specimens and 220 (21.95%) were found to be positive at greater than or equal to 10(5) colony-forming units (CFU)/mL of urine by the standard method. Of the 220 positive specimens, 210 (95.4%) were detected in 6 h or less and 177 (80.4%) were detected within 3 h. The false-positive rate was 2.3% at 3 h and 19.7% at 6 h. These findings suggest that a 6-h procedure is necessary to detect 95% or more of significant bacteriuria. Laser nephelometer is versatile and can be used for rapid screening of bacteriuria.     

A Comparative Study of the Triphenyltetrazolium Chloride (Uroscreen) Test and Conventional Methods for the Detection of Bacteriuria

Acute urinary tract infection may be preceded by and active pyelonephritis may be associated with asymptomatic bacteriuria. Treatment of asymptomatic bacteriuria may prevent or arrest active, chronic pyelonephritis and its sequelae. Consequently, there is a need for a reliable and simple screening procedure to detect asymptomatic bacteriuria in large segments of the population.The reliability and practicability of tests advocated for the detection of bacteriuria, including the new chemical triphenyltetrazolium chloride (T.T.C.) (Uroscreen) test, were evaluated. Reliability was assessed by correlating results of these tests with bacterial counts of tested urines. Significant bacteriuria is defined as the presence of 100,000 or more organisms per ml. of urine.The T.T.C. (Uroscreen) test was positive in 92.5% of cases of bacteriuria; there were 7.5% false-negative and 2.8% false-positive results. Bacteria on Gram-stained smear were found in 95.5% of the cases of bacteriuria and in 14.6% of those with non-infected urine; pyuria (more than three leukocytes per high-power field), in 60% of those with bacteriuria and in 15.9% of those with presumably non-infected urine. Bacteria were conspicuous in the urinary sediment in 91.1% of cases of bacteriuria and in 3.7% of presumably non-infected urines.The T.T.C. (Uroscreen) test fulfilled the criteria for a reliable and simple screening procedure. It should be used concomitantly with other screening tests when the urine is examined routinely.     

Neonatal Bacteriuria: A Prospective Study in 1,460 Infants

In a prospective study of 1,460 virtually consecutive neonates 14 (1%) were found to have bacteriuria, established by bladder puncture. Eleven were boys and three girls. Five of the infants with bacteriuria had symptoms suggestive of infection and were treated with antibiotics. The remaining nine were asymptomatic and remained so during a period of observation—five cleared their urine of bacteria without treatment, and four received antibiotics. Only one infant with bacteriuria had bacteraemia. Six infants had more than 10 white blood cells per mm³ in the bladder puncture urine and three had proteinuria. The blood urea was slightly raised in only two of the infants. The intravenous pyelogram was normal in all infants with bacteriuria but eight had slight or moderate vesicoureteric reflux when examined by micturating cystourethrography.     

Is screening for bacteriuria in pregnancy worth while?

A total of 4470 pregnant women were screened for bacteriuria by the dipslide method and significant growth found in 226 (5.1%). In 198 cases the urine was re-examined, in 119 by using suprapubic aspiration or catheterisation (62 (52%) samples contained bacteria) and in 79 by using midstream urine samples (26 (33%) samples contained greater than 10(8) colony forming units/1), showing the maximum prevalence of confirmed bacteriuria to be 2.6%. Overt urinary tract infection developed later in four of 80 patients with proved bacteriuria who had been given antibiotics, in one of eight untreated patients with bacteriuria, in one of 110 patients with unconfirmed bacteriuria, and in one of 226 non-bacteriuric controls. A history of urinary tract infection was given by 18% of controls and 42% of women with confirmed bacteriuria. Screening for bacteriuria and treatment with antibiotics to prevent later overt infection is expensive. Whether it is worth while and cost effective depends largely on the prevalence of bacteriuria in the local population and the proportion who develop overt infection. The screening and treatment programme reported here appeared to prevent only six cases of overt infection.     

Antibody-coated bacteria in the urine of preschool and school-aged girls with asymptomatic bacteriuria.

Urine samples from 3564 girls aged 2 to 13 years were screened for evidence of infection. Cultures were positive (bacteria count, more than 10(5)/ml) in 61 (1.7%) by the dipslide method and in 55 (1.5%) by standard culture techniques. In 13 (23.6%) of the 55, antibody-coated bacteria (ACB) were detected in the urine. The clinical, bacteriologic, radiologic and urinalysis findings in children with ACB were no different from those in children in whom the bacteria were not coated. Direct examination of uncentrifuged urine under high power revealed one or more bacteria per two high-power fields in 96% of infected urine samples and in only 7% of noninfected samples. Five or more leukocytes per high-power field in centrifuged urine were detected in 36.7% of infected urine samples but not in noninfected samples. The ACB test did not differentiate between asymptomatic bacteriuria with parenchymal scarring or vesicoureteral reflux or both and asymptomatic bacteriuria without these abnormalities.     

Six year follow up of infants with bacteriuria on screening.

OBJECTIVE--To determine the value of screening for bacteriuria in infants with special emphasis on the natural course of untreated asymptomatic bacteriuria, renal growth, and renal damage. DESIGN--Prospective six year follow up of infants with bacteriuria on screening in an unselected infant population. SETTING--Paediatric outpatient clinic. PATIENTS--50 Infants (14 girls, 36 boys) with bacteriuria on screening verified by suprapubic aspiration from an unselected population of 3581 infants in a defined area of Gothenburg. INTERVENTIONS--Children with asymptomatic bacteriuria and normal findings on initial urography were untreated, although other infections were treated. MAIN OUTCOME MEASURES--Culture of urine and determination of C reactive protein concentration every six weeks for the first six months after diagnosis, every three months from six months to two years, and every six months between two and three years; thereafter yearly urine culture. Evaluation of renal concentrating capacity with a desmopressin test; radiological examination, including first and follow up urography and micturition cystourethrography without antibiotic cover; and measurement of renal parenchymal thickness and renal surface area. RESULTS--Of the original 50 infants, 37 (12 girls, 25 boys) were followed up for at least six years. Two infants developed pyelonephritis within two weeks after bacteriuria was diagnosed; the others remained free of symptoms. 45 Infants were untreated; the bacteriuria cleared spontaneously in 36 and in response to antibiotics given for infections in the respiratory tract in eight. Recurrences of bacteriuria were observed in 10 of the 50 children, of whom one had pyelonephritis. No child had more than one recurrence. At follow up urography in 36 of the 50 children (9 girls, 27 boys) after a median of 32 months no child had developed renal damage. First samples tested for renal concentrating capacity showed significantly higher values than those from a reference population (mean SD score 0.50, 95% confidence interval 0.21 to 0.79; p less than 0.001), but the last samples showed no significant difference (mean SD score 0.08, -0.24 to 0.40; p greater than 0.05). CONCLUSIONS--Mass screening for bacteriuria in infancy results primarily in detection of innocent bacteriuric episodes and is not recommended.     

Bacteriuria amongst Pregnant Women in the Buea Health District,Cameroon: Prevalence,Predictors, Antibiotic Susceptibility Patterns and Diagnosis

Background

Bacteriuria is associated with significant maternal and foetal risks. However, its prevalence is not known in our community.

Objectives

This study was carried out to determine the prevalence and predictors of bacteriuria in pregnant women of the Buea Health District (BHD) as well as the antibiotic sensitivity patterns of bacterial isolates. It also sought to determine the diagnostic performance of the nitrite and leucocyte esterase tests in detecting bacteriuria in these women.

Methods

An observational analytic cross-sectional study was carried out amongst pregnant women attending selected antenatal care centres in Buea. We recruited 102 consenting pregnant women for the study. Demographic and clinical data were collected using structured questionnaires. Clean catch midstream urine was collected from each participant in sterile leak proof containers. Samples were examined biochemically, microscopically and by culture. Significant bacteriuria was defined as the presence of ≥10⁸ bacteria/L of cultured urine. Identification and susceptibility of isolates was performed using API 20E and ATB UR EU (08) (BioMerieux, Marcy l''Etoile, France).

Results

Significant bacteriuria was found in the urine of 24 of the 102 women tested giving a bacteriuria prevalence of 23.5% in pregnant women of the BHD. Asymptomatic bacteriuria was detected in 8(7.8%) of the women. There was no statistically significant predictor of bacteriuria. Escherichia coli were the most isolated (33%) uropathogens and were 100% sensitive to cefixime, cefoxitin and cephalothin. The nitrite and leucocyte esterase tests for determining bacteriuria had sensitivities of 8%, 20.8% and specificities of 98.7% and 80.8% respectively.

Conclusion

Bacteriuria is frequent in pregnant women in the BHD suggesting the need for routine screening by urine culture. Empiric treatment with cefixime should be instituted until results of urine culture and sensitivity are available. Nitrite and leucocyte esterase tests were not sensitive enough to replace urine culture as screening tests.     

Trial evaluation of familial asymptomatic bacteriuria]

Between September 1, 1987 and December 1, 1988, 57 cases of asymptomatic bacteriuria were distinguished in the group of 2,898 schoolgirls, aged between 15 and 20 years (mean 16.7 years). For screening purposes Griess'test modified by Sleigh was used. Bacteriologic tests have shown, that 12 out 57 mothers (21.05%) and 5 out of 39 sisters (12.82%) suffered from asymptomatic bacteriuria, while this pathology was diagnosed in 61 (2.10%) out of all control population, i.e. 66 girls. Incidence of the asymptomatic bacteriuria was 4.55% in the 66 mothers. The differences in the incidence of the infection between the whole population and mothers of the control group, and between sisters and mothers of girls with asymptomatic bacteriuria were statistically significant (p < .001 and p < .01, respectively). History of the urinary tract infections was significantly more frequent in girls with asymptomatic bacteriuria, their mothers and sisters than in the control group. Type of bacterial strains isolated from the urine, similar sanitary conditions in these families as well as the lack of ultrasonographically and renographically diagnosed urinary pathologies in 11 out of 13 girls whose mothers and sisters suffered from asymptomatic bacteriuria suggest that familial asymptomatic bacteriuria may have a genetic background.     

Rapid Detection of Gram-Negative Bacteriuria by Use of the Limulus Endotoxin Assay

The Limulus in vitro endotoxin assay was evaluated as a possible method for the prompt detection of significant gram-negative bacteriuria in children. This assay is capable of detecting endotoxin associated with intact cell walls of viable gram-negative bacteria as well as free endotoxin. Quantitative results are obtained following a 1-h incubation of Limulus lysate and 10-fold dilutions of otherwise untreated urine. A standard curve of Limulus activity and viable cell counts of Escherichia coli and Klebsiella pneumoniae in urine demonstrated that a positive Limulus reaction at a dilution of 1:100 or 1:1,000 indicated a colony count of at least 100,000 bacteria/ml. A positive Limulus reaction only from undiluted urine or at a dilution of 1:10 indicated less than 100,000 cells/ml. These experimental observations were confirmed by comparing the Limulus test with quantitative plate counts on 209 urine specimens from a mixed pediatric population. These results indicate that the Limulus assay is a simple, accurate method for rapid presumptive detection of gram-negative bacteriuria in patients where an immediate diagnosis is needed. This test would also seem promising for screening large patient populations for bacteriuria or for monitoring the effectiveness of treatment of urinary tract infections.     

Comparison of 2 methods of qualitative bacteriological urinalysis

Two techniques of the quantitative bacteriological urinalysis were compared. Hundred seventy eight samples of the urine were analysed with routine technique and paper strip test "Mast Bacteriuritest". Hundred percent conformity of both techniques was obtained in case of insignificant bacteriuria. In case of significant bacteriuria the results differed: paper tests were negative in 10% of cases. Significant bacteriuria was diagnosed in the samples in which Gould's test was positive with routine technique in 22% and with paper test in 18% of the analysed samples. It seems that paper test is valuable quantitative technique of the urinalysis because of its simplicity and low cost. It should be used, however, for the detection of the significant bacteriuria.     

A Real-Time PCR-Based Semi-Quantitative Breakpoint to Aid in Molecular Identification of Urinary Tract Infections

This study presents a novel approach to aid in diagnosis of urinary tract infections (UTIs). A real-time PCR assay was used to screen for culture-positive urinary specimens and to identify the causative uropathogen. Semi-quantitative breakpoints were used to screen for significant bacteriuria (presence of ≥10⁵ CFU/ml of uropathogens) or low-level bacteriuria (containing between 10³ and 10⁴ CFU/ml of uropathogens). The 16S rDNA-based assay could identify the most prevalent uropathogens using probes for Escherichia coli, Pseudomonas species, Pseudomonas aeruginosa, Staphylococcus species, Staphylococcus aureus, Enterococcus species and Streptococcus species. 330 urinary specimens were analysed and results were compared with conventional urine culture. Using a PCR Ct value of 25 as semi-quantitative breakpoint for significant bacteriuria resulted in a sensitivity and specificity of 97% and 80%, respectively. In 78% of the samples with monomicrobial infections the assay contained probes to detect the bacteria present in the urine specimens and 99% of these uropathogens was correctly identified. Concluding, this proof-of-concept approach demonstrates that the assay can distinguish bacteriuria from no bacteriuria as well as detect the involved uropathogen within 4 hours after sampling, allowing adequate therapy decisions within the same day as well as drastically reduce consequent urine culturing.     

Failure of Urinary Beta-Glucuronidase Activity to Localize the Site of Urinary Tract Infection

The differentiation of renal from bladder bacteriuria is difficult on clinical grounds alone. To evaluate the correlation between site of infection and urinary beta-glucuronidase activity, 46 patients with well documented recurrent bacteriuria were studied by bilateral ureteral catheterization. Urinary beta-glucuronidase activity was also determined in 46 control subjects. In general, asymptomatic patients with renal bacteriuria, either unilateral or bilateral, had levels of enzyme activity in their urine comparable to patients with infection confined to the bladder and to normals. Only 4 of 25 patients with renal bacteriuria had significant elevations of urinary beta-glucuronidase. After localization of infection, 9 of 10 patients treated with kanamycin, a potentially nephrotoxic drug, developed significant elevations of urinary beta-glucuronidase. The results of these studies indicate that determination of beta-glucuronidase activity in urine is not useful in predicting the site of infection in patients with bacteriuria but may find a role in screening for early nephrotoxicity.     

Asymptomatic Urinary Tract Infection in Gynaecological Outpatients

In this study mid-stream specimens of urine were collected from all new patients attending a gynaecological outpatient department and tested for significant bacteriuria. Those having an asymptomatic infection were folloWed up, treated, and investigated adiologically.Of 1,506 women screened for bacteriuria 82 (5·4%) were found to have a persistent infection. The predominant organism was Escherichia coli, present in 83% of infections. Treatment with sulphonamides produced a good cure rate, which was improved by ampicillin given to failures. Some patients, however, had infections that persisted or recurred despite several antibiotics. The radiological investigations showed that a high proportion of women with asymptomatic urinary infection had severe renal disease which was quite symptomless. This was more pronounced in those with persistent or recurrent infections.     

The Triphenyl Tetrazolium Chloride (Uroscreen) Test Alone and in Combination with the Gram Smear as a Screening Procedure for Significant Bacteriuria in Hospital Patients

Of 725 specimens of urine examined by the triphenyl tetrazolium chloride (TTC) [Uroscreen], pour plate and calibrated loop procedures, 30% yielded bacterial colony counts greater than 100,000/ml.; a 100% correlation was obtained among the three methods. Of 539 urine specimens containing more than 100,000 bacteria/ml., 517 (94.06%) gave a positive TTC test.Because of the high correlation between the TTC test and bacterial quantitative counts, the method of TTC in conjunction with smears was adopted as a routine procedure. Specimens which were TTC-negative and smear-negative were discarded. Of 1227 specimens from hospital in-patients and 349 outpatients, 369 urines showed significant bacteriuria (337 from hospital in-patients and 32 from outpatients). There was complete correlation between the TTC test and smear. Of 337 isolations, 27 (8.02%) gave a negative TTC test but a positive smear.     

Urinary Concentrating Ability in Women with Asymptomatic Bacteriuria in Pregnancy

The incidence of impaired renal concentrating ability in pregnant women with asymptomatic significant bacteriuria is significantly less than previously reported when osmolality readings are performed on every urine specimen obtained during the 24 hours'' deprivation of fluids. The concentrating defect is more considerable as pregnancy progresses. The lower the maximum urinary osmolality the more difficult is the treatment of the patient, and the higher the incidence of acute pyelonephritis.     

Two rapid urine screens for detection of bacteriuria: An evaluation

Five hundred twenty-five random clean catch urine specimens, collected from 339 adult females, 137 adult males, and 49 pediatric patients, were screened for the presence of bacteriuria with the Uriscreen catalase test and with the Chemstrip 2 LN dipstick. Quantitative cultures were performed on all specimens. The sensitivity, specificity, positive predictive value, and negative predictive value for the catalase test, with 10⁵ CFU/ml as the threshold for significant bacteriuria, were 91.3%, 72.3%, 33.7%, and 98.0%, respectively. Values for the dipstick were 83.9%, 77.9%, 43.7%, and 96.0%. when 10⁴ CFU/ml was used as the threshold, the catalase test had a sensitivity of 89.2%, specificity of 70.4%, positive predictive value of 37.3%, and a negative predictive value of 97.0%. Values for the dipstick at that level were 82.3%, 77.5%, 48.6%, and 94.8%. While the catalase test was more sensitive than the dipstick, it was our opinion that high rates of false-negatives associated with these methods negated the convenience of these fast and simple urine screens.The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense.     

Medicine in Society

The degree to which quantitative urine cultures and the triphenyltetrazolium chloride (TTC) reduction test can be correlated can be directly related to the species of organism involved, the actual level of bacterial population in the urine and the presence of antibiotics. The influence of these various factors is discussed and it is concluded that, depending upon the group of patients involved, the TTC test will detect 70-90% of cases of significant bacteriuria. The TTC test would appear to be a useful screening procedure in the surveillance of large outpatient populations and in the detection of bacteriuria during pregnancy, considering the difficulty of applying the technique of complete quantitative culture to these groups.     

Obstacles to progress in family planning.

Two dip-tests, Testuria and Uricult, were studied as screening tests for bacteriuria in children. Both tests showed a very good correlation with a standard method of urine culture.Testuria is easier to read and more accurate; however, it shows more “doubtful” results. Uricult presents the advantages of showing fewer “doubtful” results, and of differentiating between gram-positive and gram-negative organisms.The use of both tests should be limited to screening for bacteriuria. Certainly they are no substitute for accepted methods of urine culture.     

Detection of bacteriuria by bioluminescence: effect of pre-analysis centrifugation of specimens

N ichols , W.W., C urtis , G.D.W. & J ohnston , H.H. 1984. Detection of bacteriuria by bioluminescence: effect of pre-analysis centrifugation of specimens. Journal of Applied Bacteriology 56 , 247–257.
Three bioluminescence-based, rapid methods of detecting significant bacteriuria were applied in parallel to 514 urine specimens. The results were compared with those of a quantitative pour plate viable count method, defined as positive if ≥ 10⁵ c.f.u./ml of urine were observed. When adjusted to yield 21% falsely positive results the three rapid methods yielded 24%, 21% and 19% falsely negative results. If specimens with evidence of urethral or vaginal contamination were excluded (237 specimens remaining) the three methods yielded respectively 14%, 8% and 13% falsely negative results. A major source of disagreement between the bioluminescence-based methods and quantitative culture thus appeared to be contaminated urine specimens.