Acta Paiiutr Scand 64: 425-43 1, 1975

ASYMPTOMATIC BACTERIURIA IN SCHOOLGIRLS

I . Clinical and Laboratory Findings U. LINDBERG, I. CLAESSON, L.

A. HANSON and U . JODAL

From the Departments of Paediatrics and Roentgenology, the Children's Hospital, and the Department of Immunology, Institute of Medical Microbiology, University of Gdteborg, Gijteborg, Sweden

ABSTRACT. Lindberg, U., Claesson, I., Hanson, L. A. and Jodal, U. (Departments of Paediatrics and Roentgenology, the Children's Hospital, and the Department of Immunology, Institute of Medical Microbiology, University of Goteborg, Goteborg, Sweden). Asymptomatic bacteriuria in schoolgirls. I. Clinical and laboratory findings. Acta Paediatr Scand, 64: 425, 1!775.-Among 116 schoolgirls with asymptomatic bacteriuria detected at urinary screening, renal parenchymal reduction was found in 10.3 %, while reflux was found in 20.7 %. Only 30 % of the 116 patients had a history referable to earlier urinary tract infection and there were remarkably few girls with an increased sedimentation rate (4.4 %), C-reactive protein (9.5 %), pyuria (25.8%) or lowered concentrating capacity (3.4%) at the time of detection of their bacteriuria. No method was found efficient in predicting lesions on the pyelogram and urethrocystogram, but determination of renal concentrating capacity and C-reactive protein was of some value in predicting parenchymal reduction. The girls with pyelonephritic changes on the pyelogram had a mean renal concentrating capacity significantly lower than the girls without changes. The concentrating capacity of the girls with reflux but without renal scarring and those bacteriuric patients without radiologically demonstrated defects did not differ significantly from the age-related normal values.

KEY WORDS: Asymptomatic bacteriuria, schoolgirls, clinical, roentgenological findings, renal concentrating capacity, pyuria, C-reactive protein, sedimentation rate

Urinary tract infection (UTI) detected by screening is usually referred to as asymptomatic bacteriuria (ABU). The patients have either no symptoms or such minor symptoms that a doctor has not been consulted. The prevalence in a population of healthy schoolchildren is 1.1 % in girls and 0.03 % in boys, according to Kunin et al. (8,9). Savage et al. found a prevalence of 1.6% in 5-year-old girls screened on entry to primary school (16). In a study from Lund, 0.8% of 4-year-old girls and 1.5% of schoolgirls had ABU (11, 17). In Goteborg, a prevalence of 0.7% was found among 4300 schoolgirls (5). Since the long-term consequences of ABU in childhood are uncertain, its association with renal infection vague, and the 28-752873 Acta Pzdiatr Scand 64

development of renal parenchymal reduction as well as the need for and/or best form of treatment is still unknown, we wanted to pursue a detailed investigation of the clinical characteristics and course, the value of various diagnostic measures, and the therapy of patients with ABU. This first paper is concerned with the roentgenological findings and their relation to pyuria, sedimentation rate, C-reactive protein (CRP), concentrating capacity, and a history of earlier infections.

MATERIAL AND METHODS Since 1970 about 19000 girls a year are routinely screened for bacteriuria in Goteborg schools when 7, 11, 14, and Acta Pediatr Scand 64

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I/. Lindberg et al.

16 years old, using a chemical test, the BM Test Nitrite (Boehringer Mannheim GmbH, Mannheim, BRD). During the autumn of 1971 and throughout 1972 schoolgirls 7-15 years old were referred to the Paediatric Department at the Children's Hospital for further examination because of at least two positive tests in the screening program. Of these, I16 with significant bacteriuria ( 3105iml) with the same organism in two consecutive urine samples and no symptoms at the first visit to the hospital, were included in the study. In addition to the controls for renal concentrating capacity presented by Winberg (19). a group of 50 girls of the same ages were, for comparison, chosen from patients with earlier UTI. They had had negative urine cultures during the preceding 6 months. Intravenous pyelography and micturating cysto-urethrography performed in 39 of these 50 girls were normal. A careful history was obtained to reveal symptoms of previous UTI and enuresis (involuntary urination after 5 years of age). A physical examination including measurement of height, weight and blood pressure was done. Urine was collected as a midstream sample after careful cleaning of the external genitalia, and was kept at +4"C until semi-quantitatively cultured (12). To obtain a second sample the patients were instructured to collect a morning midstream specimen which was cultured with a dipslide, (Uricult", Orion Pharmaceutical Co., Helsinki, Finland) at home. The slide was sent by mail to the laboratory and read after incubation overnight in 37°C. Classification of the bacteria and 0-groupingofE. coli were performed as earlier described (12). The urinary white cell excretion was determined by counting the leucocytes in uncentrifuged urine using a Fuchs-Rosenthal chamber. A count of >50 cells/mm3 was regarded as pathologic ( 2 ) . Blood samples were obtained and analysed for micro-sedimentation rate and CRP (14). A micro-sedimentation rate >20 mmih and CRP >I0 pg/ml were considered abnormal ( 6 ) . The concentrating capacity of the kidneys was estimated by freeze point reduction in two consecutive urine samples obtained at home after fluid deprivation for at least 15 hours. The highest value was noted. The age-related normal values of Winberg (19) were used as a reference. If the concentrating capacity was (814 mOsmll the test was repeated. Intravenous pyelography (IVP) and micturating cystourethrography (MCU) were performed on all 116 girls with ABU. The IVP was appraised with regard to pyelonephritic changes, using the criteria of Hodson (4). Patients with calyceal deformation or dilatation were grouped according to the number of calyceal groups involved. The degree of parenchymal reduction was estimated according to a scale in which + meant a minor shift of the renal outline, + + a distinct parenchymal reduction, and + + + an almost complete reduction of parenchyma corresponding to a deformed calyx group (Fig. 1). Maximum length of the kidneys was measured on roentgenograms obtained without compression and with the patient in a supine position. In order to reduce the radiation dose to the gonads during the MCU and to attain diagnostic information during the filling as well as micturition, fluoroscopy and 70 mm cine technique were used. As a rule, exposures in both antero and lateral projection were obtained. Exposures were alActa Paediatr Scand 64

ways made before micturition in order to reveal reflux occurring during filling of the bladder. The reflux was rated in four degrees: I, reflux in a non-dilated ureter and not reaching the kidney pelvis; 11, into the pelvis but without dilatation; 111, into the kidney pelvis with dilatation of the pelvis and ureter, and IV, into the kidney pelvis with extreme dilatation of the pelvis and ureter (21). Stutisticul methods

The Wilcoxon test for two samples and Fisher's exact test for 2 r2 contingency tables were employed.

RESULTS Radiological investigations IVP revealed 12 children (10.35%) with calyceal changes and parenchymal reduction suggestive of previous pyelonephritis (Fig. I and Table 1). In 2 girls there were bilateral changes. Reflux was diagnosed in 11 of these 12 girls (Tables 1 and 2). Another 13 girls with normal IVPs had reflux ( 1 1.2%), making a total of 24 girls with this finding (20.7 %). The reflux was bilateral in 10 girls. The mean degree of reflux did not differ between the groups with and without renal parenchymal changes (Table 2). Five girls had a double collecting system (4.3%) and a diverticulum of the urinary bladder was found in 3 girls (2.6%). History Of the 12 girls with parenchymal reduction of the kidney, 2 (17%) had previously been treated for febrile UTI, and 3 for afebrile infections (Table 3). Among the 13 patients with reflux without detectable changes of the kidneys, 2 ( 15 %) had had febrile and 2 afebrile UTI (Table 3). In the group without parenchymal reduction or reflux (91 girls), 4 (4%) had been treated for febrile UTI and 22 girls had had symptoms of afebrile infections. Thus 30.1% of the group had a history that could be related to UTI. Abnormal findings on IVP were not significantly more common in children with a past history of UTI (p =0.34for febrile or afebrile infection and 0.19 for febrile infection). Neither were MCU abnormalities significantly more common in this group

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for febrile infection) (Table 3). However, the p-value for a past history offebrile UTI and abnormal findings on IVP or MCU was 0.06. A history of primary enuresis was found in 22 girls (18.9%, 21 nocturnal and one diurnal), 9 of whom (7.7 %) still had a nocturnal enuresis when admitted. Of these 9 girls, one was found in the group with parenchymal reduction, and 2 among the girls with reflux but without kidney changes (Table 3). Secondary enuresis was present in 9 girls (7.7%, 2 nocturnal and 7 diurnal), all without renal parenchymal reduction or reflux (Table 3). Neither on IVP nor on MCU were there significantly more abnormal findings ( ~ 3 0 . 2 7 in ) girls with enuresis (Table 3).

Laboratory findings E. coli were found in the urine of all except one girl in whose urine Klebsiella-Aerobacter was isolated. Pyuria, i.e. white cell excretion >50 cells/mm3, was found in 3Ogirls (25.8 %). Six of the 12 patients with renal scarring and 4 of the 13 girls with reflux but without detectable renal CONC

CAPACITY n SD

N

u

PARENCHYMAL REDUCTION

12

REFLUX WITHOUT PARENCH RED

13

869 965

a NO

CtiANGES

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Fig. I . Classification of parenchymal reduction: +, a minor shift of the renal outline; ++, a distinct parenchymal reduction; +++, an almost complete reduction of parenchyma corresponding to a deformed calyx group. From patients 6, 9 and I I in Table 1.

Physical examination All children appeared well and general examination did not reveal any abnormalities. None had an elevated blood pressure. On the Karlberg et al. growth chart for Swedish girls, 6 to 18 years old (7), all of the patients were normally distributed between +_2S.D. for height and weight except for onegirl who was between -2 and -3 S.D. for weight.

@ =0.51 for febrile or afebrile infection and 0.22

ABU PATIENTS

427

91 116

1011 991

50

1015

'125 t 97

89 '-117

f

CONTROLS

of patients OIo

0

f

99

or controls

507 Lo-

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Acta Pediatr Scand 64

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U . Lindberg et al.

Table 1, Radiological and laboratory findings in 12 girls with ABU and renal parenchymal reduction Intravenous pyelogram ~

Patient no. I 7

i

3 4 5 6 7

8 9

Age

12

10

II 10 10

II 12

8 8

a

Deforrnation in one calyx group

15 IS 15 14 14 14

Deformation in more than one calyx group

+ + +

Reduction of parenchyma

Renal length (cm)

Degree

Side

Right

Left

+++ +++ ++ +++ +++ + + +++ ++ ++ +++ +

Bilat. Right Left Left Left Right Left Left Right Bilat. Right Right

11.5

12 12.5 9 8

13.5 12 12.5 13.5 9 12.5 11"

9 8 6 8.5

6.5 1 I .5"

13 10

13 10 12.5 10

Micturition cystou rethrogram (Degree of reflux) Right 11, left I No reflux Bilat. 11 Left I1 Left I Right I Bilat. 11 Left I1 Bilat. I1 Bilat. I1 Right I Right I

Duplication of pelvis.

changes had pyuria (Table 4). Pyuria was thus group with renal scarring, one in the group with significantly more common @=0.05) in girls reflux only, and 6 among the girls without with parenchymal reduction. In contrast, roentgenological changes (Table 4). Abnormal abnormal findings on MCU in patients without findings on IVP were significantly more comrenal scarring were not significantly more pre- mon @=0.01) in children with increased CRP valent @ =0.53) in children with than without but MCU abnormalities were not (p =0.75) pyuria (Table 4). (Table 4). Micro-sedimentation rate >20 mm was found in 5 girls (4.3%), 2 in the group with Renal concentrating capacity kidney damage, one in the group with reflux, The 116 bacteriuric girls had a mean urinary and 2 among the girls without roentgenological osmolality of 991k 117 mOsm/l after fluid dechanges (Table 4). The correlation between privation. The 91 girls without renal scarring or increased micro-sedimentation rate and radio- reflux had a mean of 1011k89 mOsm/l, while logical abnormalities was not statistically the 12 girls with pyelonephritic changes on the pyelogram had 869k125 mOsm/l (Fig. 2), a significant (p30.07) (Table 4). Increased quantity of serum CRP, >I0 significantly lower value (p0.05) from patients without roentgenological changes or that of the 50 girls without bacteriuria, who had

Number of patients

429