Antibody-coated bacteria and urinary tract infection

Volume 94 Number 3 were only used to rank the lamps in order of their blue light output. The Table provides values of energy in watts because values of watts per square centimeter are dependent upon the geometry of the fixture, the distance from the lamps, the reflectivity of the hood, the orientation of the sensor, the aperture of the sensor, and the spectral characteristics of the sensor. Since a variety of light fixtures are used throughout the country, we attempted to provide data and conclusions that would be of general use, independent of the light fixture, the distance to the child, and similar variables. If a lamp fixture of a different manufacturer is employed or is used at a different distance, the conclusions are still valid, since we are merely talking about energy output of lamps. Energy in microwatts per square centimeter received by the infant is, indeed, a different value and can be determined both through calculations or direct measurement. We have made some of these measurements, and find good agreement between the calculated and the measured values. The total irradiance received from lamp arrays will differ if the individual lamps are not always mounted in the same fashion. We suggested alternating the two types of lamps so as to achieve a reasonably uniform distribution of light intensity across the patient area and to get as much color uniformity as possible. It would not be unusual to find 10% or more variation from a point directly under the center of the fixture to a point a foot or so to the side, nor would it be unexpected to find a similar variation if the special blue lamps are placed in the center as opposed to alternating them. There is additional variation depending upon spacing and the design of the lamp fixture. We sought to provide data to allow comparison of various lamp combinations, independent of the fixture. We did not contend that our recommended combination of lamps provides optimal irradiance for phototherapy. Rather, we sought to optimize the color while maintaining the blue component at a high level. It was not our sole intention to maximize the level of blue light energy the child receives; had this been the case, we would have had to address the issue of distance between fixture and patient, and other factors that affect the amount of energy delivered to the patient. We sought to compare different lamps and to suggest that it is not necessary to use an array of all blue lamps to get a high level of blue light energy. The measurement of 9 microwatts per square centimeter per nanometer appears reasonable; our measurements and calculations have yielded a value of about 10.6. But, meaningful comparisons cannot be made unless one controls for distances, characteristics of the fixture, etc. Measurements of this sort are also highly dependent upon the spectral characteristics of the measuring device. Knowing the total blue light irradiance of an array of lamps does permit conclusions regarding clinical effectiveness in photodegradation of 6ilirubin, because (1) other studies have demonstrated a direct correlation (dose-response relationship) between the two, (2) the recommended lamps have been used effectively in the past, and (3) light energy is a linear function, permitting summation of energy from the various light sources as long as the geometry is considered. Assuming the light fixture is

Editorial correspondence

5 11

unchanged, comparison of spectral characteristics of various lamps should be clinically useful. Emanuel Furst, Ph.D. Director, Biomedical Engineering Thomas Harris, M.D. Clinical Director, Neonatology The University of Arizona Health Sciences Center Tucson, A Z 85724

Antibody-coated bacteria and urinary tract infection To the Editor: In the February, 1978, issue of THE JOURNAL Hellerstein and associates ~have concluded in contrast to all previous studies that there is poor correlation between the presence of antibody-coated bacteria and the presence of upper urinary tract infection. To establish the site of infection, the authors employed the bladder washout technique. Yet Jones et alz and more recently Canarelli et al, 3 using the same technique in adults, have reported a good relationship between the results of the tests for antibody-coated bacteria and the site of infection. We have studied the value of the detection of antibody-coated bacteria in urine sediment in 77 urinary tract infections in 67 children. For ethical reasons, we could not use the bladder washout technique, but all diagnoses of urinary tract infection were established by suprapubic bladder puncture or by catheterization of the bladder during urologic investigation. The infections were carefully divided on the basis of clinical, biologic, and, most frequently, radiologic criteria into three diagnostic groups. Our criteria are very strict and so, in addition to the groups considered to have upper or lower urinary tract infections, we had a doubtful group (comprising 35% of the infections) in which the site of infection was uncertain. Table I gives the results of the immunofluorescence tests for antibody-coated bacteria in the three diagnostic groups. The results indicate a good relationship between the presence or absence of antibody-coated bacteria and the site of the infection in the kidney or in the bladder, respectively (X2 14.033, P < 0.001). Yet in 17.4% of the lower urinary tract infections we found a positive result and in 29.6% of the upper urinary infections negative result. In 31 patients, we compared clean voided urines with those obtained by suprapubic aspiration with regard to the results both of culture and of tests for antibody coated bacteria. In three patients, all female, there was disagreement between the results ori the specimens taken by the two techniques; antibody-coated bacteria were found in the sediment of the clean voided urine and the culture was positive, but both these tests were negative on the urine obtained by suprapubic aspiration a short time after the first specimen. These data are in agreement

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Editorial correspondence

The Journal of Pediatrics March 1979

bacteria in the urine of children with urinary tract infections, Acta Paediatr Scand 65:639, 1976. Braude R, and Block C: Proteinuria and antibody coated bacteria in the urine, N Engl J Med 297:617, 1977.

Table I

Lower urinary tract infection Upper urinary tract infection Undetermined Totals

Negative immunofluorence

Positive immunofluorence

19 (82.6%)

4 (17.4%)

23

8 (29.6%)

19 (70.4%)

27

11 (40.8%)

16 (59.2%)

27

38

39

77

Total

with the hypothesis that contamination of specimens during collection could lead to positive results and hence misinterpretation of the significance of positive results in the test for antibodycoated bacteria. The reasons for these results are not clear but various possibilities have been invoked'-~: For false negative results: the undefined effects of therapy; the special physicochemical properties of the urine; and the delayed or absent antibody formation that may occur in very young children. For false positive results: the role of associated proteinuria; and the extrarenal production of antibodies. These hypotheses do not, however, explain how the contaminating bacteria become antibody coated. Although we do not draw the same conclusions as Dr. Hellerstein, i.e., that the relationship between the site of the infection and the presence or absence of antibody-coated bacteria is poor, we do consider that this test has only statistical value and that undue reliance on it in individual cases will lead to some false conclusions.

Robert Denis, M.D. Hubert Van Achter, Ph.D. Jean-Paul Butzler, M.D. Frans Demeuter, M.D. Departments of Pediatrics and Microbiology Free University of Brussels St. Pierre Hospital Rue Haute 322 1000 Bruxelles Belgium REFERENCES 1. Hellerstein S, Kennedy E, Nussbaum L, and Rice K: Localization of the site of urinary tract infections by means of antibody-coated bacteria in the urinary sediments, J PEDIATR 92:188, 1978. 2. Jones SR, Smith JW, and Sanford JP: Localization of urinary tract infections by detection of antibody-coated bacteria in urine sediment, N Engl J Med 290:591, 1974. 3. Canarelli B, Descamps JM, Coevoet B, Fournier A, and Orfila J: Localisation de l'infection urinaire par l'ttude en immunofluorescence de la bacteriurie, et sa validation par la technique du lavage v6sical de Fairly, Nouv Presse Med 7:289, 1978. 4. Rusmans LW, and Vosti KL: Antibody-coated bacteria, JAMA 237:531, 1977. 5. Forsum U, Hyelm E, and Jonsell G: Antibody-coated

l ep y To the Editor: The presence of antibody-coated bacteria in urinary sediments has been shown to correlate closely with upper urinary tract infection in adults." -~However, our studies in children showed poor correlation? The communication from Denis and associates does not contribute to the resolution of these differences since their clinical and radiologic criteria for the localization of the site of infection do not clearly separate upper from lower urinary tract infections. In our opinion, the validity of a study to evaluate this or any other new test depends on the reliability of the reference method with which the new test is compared. A number of investigators, using direct localization procedures, have shown that upper urinary tract infections may occur in the absence of clinical symptoms, of vesicoureteral reflux, and of parenchymal reduction. 4-THarding and associates? using the bladder-washout technique for localization of the site of infection, recently reported that three of 37 women with proved upper urinary tract infections had lower urinary tract symptoms and 18 were asymptomatic. Three of the 14 patients in Harding's study with bladder-washout proved lower urinary tract infections had symptoms of upper urinary tract infections, five had lower urinary tract symptoms, and six were asymptomatic. The bladder washout procedure, which we used as the reference method in our studies, is generally accepted as one of two or three reliable direct methods for localization of the site of a urinary tract infection?, s-u We have continued our examination of urinary sediments for antibody-coated bacteria in conjunction with studies to evaluate lactate dehydrogenase isoenzymes for localization of the site of urinary tract infections. Our updated experience with the antibody-coated bacteria test is shown in Table II. These data do not show a significant relationship between antibody-coated bacteria in the urinary sediment and infection of the upper urinary tract (X~ = 1.735 P > 0.1). We are not able to explain the high correlation between antibody-coated bacteria and upper urinary tract infections in adults and the lack of such correlation in pediatric patients. H. One problem encountered in analyzing the data from various investigative groups is the lack of uniform criteria for what constitutes a urinary sediment which is "positive" for antibodycoated bacteria.' ~. ~- ,2 Thomas and associates ~ consider a urinary sediment positive for antibody-coated bacteria when at least 25% of the organisms in each microscopic field are emitting bright, apple-green fluorescence. Jones TM considers a specimen positive for antibody-coated bacteria if "at least two uniformly fluorescent bacteria are seen in 200 site fields with the use of a microscope with 100 • objective and 15 ocular. The intensity of fluorescence is not taken into consideration." Harding et al ~