The incidence of asymptomatic bacteriuria and pyuria in infancy

T h e J o u r n a l of P E D I A T R I C S

57

The incidence of asymptomatic bacteriuria and pyuria in infancy A study of 400 inJants in private practice

Two hundred male and two hundred [emale in[ants were surveyed [or asymptomatic bacteriuria and pyuria while presenting [or routine care in a private pediatric practice. The clean voided specimen was made accessible with the Pediatric Urine Collector at a remarkably low rate o[ contamination. On the initial screening 2 per cent o[ the [emale and no male in[ants showed bacteriuria. With repeated study o[ the same in[ant population the incidence o[ bacteriuria rose to 4.5 per cent o[ the [ema[e and 0.5 per cent o[ the male in[ants. The most reliable single screening procedure was the quantitative colony count, but the value o[ repeated screening by history, routine urinalysis, as well as by quantitative colony count to exclude urinary injection in the in[ant was emphasized.

Martin F. Randolph, M.D., "~ and Michael Greenfield, M . D . e''x" DANBURY, CONN.

I N R g 13E N T years emphasis has been placed on the major role played by urinary tract infection in the morbidity and mortality of infancy and childhood? -3 Autopsy studies reveal an incidence of 1.64, s to 4.5 ~ per cent of pyelonephritis. Morbidity studies comprised of outpatient department and hospital populations render an estimate rangFrom the Danbury Hospital, Danbury, Conn., Department o[ Pediatrics, Yale University School o[ Medicine, and Department o[ Urology, Albert Einstein College o[ Medicine. This study was supported in lull by a grant #ore the Upjohn Company, Kalamazoo, Mich. ~Address, 70 Deer Hill. Danbury, Conn. Department of Pediatrics, Yale University School o] Medicine. "" Diplomate, American Board o[ Ur logy. Det~artment o[ Urology, Albert Einstein College o[ Medicine.

ing from 0.82 to 5.87 per cent of s y m p t o m a t i c urinary infection. It was thought that true morbidity (symptomatic and asymptomatic infection) might better be derived from the systematic study of the general population presenting in a private pediatric office for routine care. Estimates of urinary tract infection have been especially sparse in the infant group because the "clean" specimen has been thought to be quite inaccessible by any means short of catheterization. 8-1~ T h e acceptance of the clean midstream voided specimen in the adult 11-~3 and the use of the quantitative colony count to separate contamination from true infection 11-18 have greatly facilitated epidemiologic study of urinary tract infections.

58

July 1964

Randolph and Greenfield

Table I

Male Female

Age ( m o n t h s )

o;o

12

65 62

38 38

1,;;o 40 31

24

Total

57 69

200 200

count; (3) statistics on the incidence of persistent bacteriuria and pyuria in an asymptomatic infant population; and (4) impressions as to the normal n u m b e r of white blood cells in the urinary sediment in infancy (the first 2 years of life). MATERIAL

Table II. U r i n a r y diary ~ Hours

Damp

7 A.M. 8 A.~t.

--

Very wet

Wet .

.

.

Stream

D istress

.

--

AND

METHODS

T h e study was begun M a r c h 23, 1962, and subsequently involved 200 male and 200 female infants. Serial collections were begun at the ages shown in Table I and extended over a 13 m o n t h period.

9 A.~. ADMISSION

7P.M. ~For two 12 hour periods leave off rubber ,ants and check diaper every one-half hour. Record " d a m p , . . . . w e t , " or " v e r y w e t . " Stream--record as " f u l l , " " i n t e r r u p t e d , " " d r i b b l e , " " m i s d i r e c t e d , " or " f o r : t e d . " Distmss--"colicky p a l n , " "excessive g a s , " or " i r r i t a b i l i t y . "

Table I I I . Urinary colony count of 200 asymptomatic male infants 1. 2. 3. 4. 5. 6.

The number of male infants surveyed Less than 1,000 colony count 1,000 to 10,000 colony count 10,000 to 100,000 colony count Greater than 100,000 colony count Persistent bacteriuria

200 40 151 7 2 1

Table IV. Urine colony counts of 200 asymptomatic female infants Number of female infants surveyed Less than 1,000 colonies counted per ml. 1,000 to 10,000 colony count 10,000 to 100,000 colony count Greater than 100,000 colony count Persistent bacteriuria

200 11 164 14 11 9

I t was felt that a practicaI extension of this voiding technique was needed for the early diagnosis of urinary tract infection in the infant age group. Following is an office screening procedure presenting: (1) a practical device ~ for the routine collection of the "clean" specimen in the infant, male or female; (2) a simple one-step loop-surface agar method for the quantitative colony ~Pediatrlc Urine Collector, courtesy of Sterilon Corporation, Buffalo, N. Y.

TO

THE

STUDY

Infants were routinely admitted to the study if (1) they had no history of urinary tract infection, (2) they were not receiving antimicrobial drugs at the time and had not received them for at least 1 m o n t h prior to admission to the study, (3) if they had no symptoms or physical findings referable to the urinary tract. METHOD

OF STUDY

'Patients under 1 year of age were usually seen every m o n t h and those over 1 year, quarterly. A history and physical examination were done on each visit and a urine specimen analyzed and cultured. T h e mother was carefully questioned about frequency, infrequency, type of voiding stream, evidence of abdominal distress, and unexplained fever. More often than not, parents had no clear idea of how often or how well an infant "wet," and they seldom observed the "stream." For this reason the urinary "diary" approach was found useful (Table II). A copy of Table I I was given to the mother and explained. For 2 separate 12 hour periods she was asked to check the degree of wetness of the baby's diaper every one-half hour and record as " d a m p , " "wet," or "very wet" in the space allotted. If she were fortunate enough to see the baby void she was to record the stream "full," "mis, directed," "interrupted," or a "dribble." This written a p p r o a c h seemed to increase the mother's awareness of how to provide a good history and it made terminology more

Volume 65

Number 1

Asymptomatic bacteriuria and pyuria

59

T a b l e V. U r i n e colony counts (thousands) b a c t e r i a isolated on one culture a n d not r e p r o d u c i b l e on subsequent cultures (i.e., c o n t a m i n a n t s ) Age (months)

I0 to 20

1 3 12 18

3 2 2 2

*Aero ~

Aerobacter

tHEC

hemolytic E s c h e r i c h i a

z

Aero* Aero HEC HEC

20 to 50

50 to 100

Over 100

3 HECt 2 HEC 2 HEC

3 HEC 1 HEC 1 HEC

Aerogenes. coli.

m e a n i n g f u l to the mother. Since this observation only involved 2 r a n d o m l y selected 12 h o u r periods at the m o t h e r ' s convenience it was not r e g a r d e d as time-consuming, and the p a r e n t s seemed to c o o p e r a t e efficiently as i n d i c a t e d b y the r e t u r n Of these charts on the next visit. A n i n f a n t became suspect of h a v i n g s y m p t o m a t i c u r i n a r y t r a c t infection a n d was excluded from the s t u d y if: 1. H e was d r y for a b n o r m a l l y long periods. 2. H e d e m o n s t r a t e d frequency with d a m p r a t h e r t h a n w e t diapers at close intervals. 3. His s t r e a m was a b n o r m a l . 4. T h e r e were r e c u r r e n t or persistent evidences of a b d o m inal distress. U r i n e was then o b t a i n e d at close intervals for complete e x a m i n a t i o n and culture. EXCLUSION OF SYMPTOMATIC CASES F o u r female a n d four male infants with s y m p t o m a t i c u r i n a r y t r a c t infections were e x c l u d e d f r o m the study. T h e four m a l e infants i n c l u d e d two cases of u r e t h r a l stricture, b l a d d e r neck contracture, a n d hair ligature a b o u t the penis. T h r e e of the female infants h a d u r e t h r a l m e a t a l stenosis a n d one h a d resection of lower pole of the kidney p e r f o r m e d elsewhere for u r e t e r a l obstruction. I n the interest of the widest possible application of our t e c h n i q u e local conditions in the p e r i n e a l area, e.g., d i a p e r dermatitis, impetigo, e r y t h e m a toxicum, balanitis, did not exclude the p a t i e n t from the study, nor was a n y special p r e p a r a t i o n o r d e r e d of the p e r i n e a l a r e a p r i o r to a p p l y i n g the P e d i a t r i c U r i n e Collector. T o our surprise, such cond i t i o n s did not alter the colony count significantly.

COLLECTION

OF URINE

A Pediatric U r i n e C o l l e c t o r (Fig. 1) was a p p l i e d to the grossly clean dry p e r i n e a l area of the infant w i t h o u t any previous att e m p t to cleanse or p r e v e n t c o n t a m i n a t i o n ; our goal was the use of the simplest technique c o m p a t i b l e w i t h m i n i m a l c o n t a m i nation. W h e n a specimen was not o b t a i n a b l e in the office, the m o t h e r was given a Pediatric U r i n e Collector a n d i n s t r u c t e d to refrigerate the h o m e - d r a w n sample i m m e d i a t e l y a n d b r i n g it directly to the office within 24 hours. U r i n e specimens were i m m e d i a t e l y T a b l e V I . Pyuria; 200 a s y m p t o m a t i c female infants* WBC/ HPF

WBC/ HPF

to 10

10 to 20 0 1 2 2 5

Age (months)

I

0 to 6 7 to 12 13 to 18 19 to 24 Total

6 4 1 8 19

WBC/HPF More than 20 2 1 2 2 7

*Those w i t h n o cells per high-power field ~- 169. T h o s e with a n y cells p e r higfi-power field ~_~ 31.

T a b l e V I I . Pyuria; 200 a s y m p t o m a t i c male infants*

Age (months) 0 to 6 7 to 12 13 to 18 19 to 24 Total

WBC/ HPF 1 to 10 1 1 0 1 3

WBC/ HPF

WBC/HPF 10 to 20 More than 20 2 0 0 0 0 0 0 0 2 0

*Those with n o cells per h i g h - p o w e r field ~- 195. Those with a n y cells per high-power field ~ 5,

60

Randolph and Greenfield

July 1964

counted at 24 hours. Bacteria could usually be identified by colony characteristics. However, Gram stain and simple fermentation studies were done when indicated. Since the inoculum was 0.01 ml., a determination o f the number of colonies per milliliter of urine was made by multiplying by 100. All specimens were routinely screened for protein and glucose by the dip stick "Combistix '''x method. E X A M I N A T I O N OF THE

F i g . 1. P e d i a t r i c U r i n e C o l l e c t o r .

refrigerated at 0 to 4 ~ C. in the office and examined within 4 hours. M A T E R I A L S AND M E T H O D S Loop-surface agar technique and the quantitative colony count. The Loop. ~ This instrument is a platinum (96.5 per cent), rhodium (3.4 per cent) fused loop with a 4 mm. inside diameter and 75 mm. shank, factory calibrated to deliver 0.01 ml. identical with a model used in the dairy industry for milk testing. After flame sterilization the loop was used to streak a blood agar plate with a loopful (0.01 ml.) of undiluted, well-mixed urine. Blood agar was used for optimum growth, broader bacterial cultivation, and for certain cultural characteristics that could more easily be "read." However, if Proteus was cultured, MacConkey's media was inoculated to eliminate swarming and allow accurate counting. The cultures were incubated at 37 ~ C. and the colonies read and ":~A. H. Thomas and Company, Philadelphia, Pa.

SEDIMENT

When sufficient quantity allowed, 10 ml. of urine were centrifugedt at 2,500 r.p.m. for 5 minutes, the supernatant was poured off, and 0.1 c.c. of a well-mixed sample of the sediment was examined immediately under a 22 mm. coverslip. Ten widely scattered fields were explored with low-power (MOO) and ten widely scattered fields were examined with high-power (• objectives. The number of red blood cells, white blood cells, and casts were recorded per high-power field. If fewer than one per highpower field, they were recorded as "occasional." Bacteria were recorded as "few" or "many." OF URINARY TRACT I N F E C T I O N AND S E L E C T I O N

DEFINITION OF THE

PATIENT

FOR

UROLO,GICAL STUDY We regarded as "suspect" a colony count of 10,000 per milliliter of urine and repeat specimens for culture were obtained at at least 24- to 48-hour intervals. However, true bacteriuria was diagnosed only with colony counts over 100,000 per milliliter on 3 consecutive cultures, the last 2 specimens collected by one of us in the office after cleaning the perineum with hexachlorophene. The urinary sediment was simultaneously studied for formed elements and bacteria and a detailed history as outlined in Table II was documented.

"X'Combistix Reagent Strips, courtesy of Ames Co., Inc. tThe Gomco Surgical Mfg. Corp., Buffalo, New York. Model No. 386.

Volume 65 Number 1

Pyuria alone was not reliable as a criterion for infection. Initially we regarded 5 or 6 white cells per high-power field as the threshold of pyuria. 13 However, as the study progressed, pyuria of less than 20 white cells per high-power field i n the absence of bacteriuria did not persist, i.e., all those with persistent pyuria also had bacteriuria. Thus, persistent bacteriuria, i.e., greater than 100,000 colonies per milliliter on 3 consecutive specimens properly obtained and cub tured, ultimately became the single criterion for urologic study. One infant (M. P.) was recommended for study because of one pus cast. She subsequently showed bacteriuria on the fourth and fifth cultures. RESULTS Incidence of Persistent Bacteriuria. It was our expectat!on that contamination would be a special problem in the diapered age group with no preparation beyond wiping the perineal area dry2, 1~ The very low contamination rate recorded below was one of the salient findings of the study, allowing as it does, the use of the Pediatric Urine Collector with minimal preparation of the perineum. Perhaps the answer is threefold: (1) the construction of the Pediatric Urine Collector which is remarkably adhesive about the genitals and excludes the rectum, (2) the immediate refrigeration of the urine specimen (a convenience that most hospital wards and outpatient departments do not have or do not take advantage of) inhibiting further bacterial multiplication, (3) the clean perineum of the infant female and the circumcised infant male. Suffice it to say that the following results support the contention that cleansing of the grossly clean infant is not necessary prior to applying the Pediatric Urine Collector to the female and to the circumcised male. Male. Only 1 male infant showed a colony count of 100,000 per milliliter on initial screening. He was eliminated by the repeat specimen. A second male (K. M.) was classified as having bacteriuria only after repeated screening over an 8 month period, giving a final incidence of 0.5 per cent of bacteriuria

Asyraptomatie bacteriuria and pyuria

6 1

in the 200 male infants surveyed. Urologic study of K. M. including voiding cystourethrograms and cystoscopy revealed a contracted bladder neck, bladder neck trabeculation, and bilateral ureteroceles. All patients with colony counts greater than 10,000 were excluded by subsequent negative cultures. Females. Seven infants (2.8 per cent) showed a colony count greater than 100,000 on initial screening. Five of these persisted with subsequent Cultures. Four additional infants were classified as having bacteriuria on later routine cultures (see Table V I I I ) , giving a final incidence of persistent bacteriuria for the female infants of 4.5 per cent (Table I V ) . Those with colony counts over 10,000 were excluded by subsequent cultures. It will again be noted that 5.5 per cent of the female infants after repeated screening had bacteriuria greater than 100,000 colony count and in 4.5 per cent of these infants true infection persisted after hexachlorophene cleansing of the perineum. Thus, only two female infants showed contamination, an incidence of 1 per cent. The incidence of contamination in the male infant was 0.5 per cent (one infant). A glance at the organisms isolated (Table V) revealed them all to be potential pathogens. Thus, as a screening procedure, the identification of the organism even in a pure culture (as these were) did not help one differentiate contamination from infection without the colony count. Of the 10 infants, 1 male and 9 females classified as having urinary tract infection and recommended for urologic study, 2 females were lost to follow-up without further investigation. A summary in tabular form of Table V I I I . Clinical and laboratory summary; 400 asymptomatic male and female infants Incidence o[ Bacterluria Pyuria Cylindruria

Female (200 infants)

Male (200 in[ants)

4.5 % 3 % 0.5 %

0.5 % 0 0

62

Randolph and Greenfield

July 1964

T a b l e IX. O n e male and nine female infants with b a c t e r i u r i a - - r e v i e w of clinical a n d laboratory findings

Patient

Sex

Age

Vo. neg. U.C. prior to dx o/ bacteriuria

H.S.

F

20 months

2

Yes

Not done Fever of undetermined origin

Not done

Not done

M.C.

F

6 months

0

Yes

Not done Fever Failure to thrive

Not done

Not done

J.T.

F

4 months

0

Yes

Neg.

Variable voiding pattern, i.e., frequency, infrequency

Bladder trabecu- Refluxing right lations ureter Bladder neck contracture

H.K.

F

12 months

2

Yes

Normal

None

Not done

V.C.

F

12 months

0

Yes

Normal

Frequent voiding of small volume

Normal findings Normal findings

M.P.

F

22 months

3

No

Normal

"Colic" 1st 6 months Scant voiding frequently and infrequently

Bladder trabecu- Left vesicorenal lation high pressure Urethral reflux stricture Bladder neck eontraeture

M.H.

F

22 months

2

No

Normal

Bladder trabecu- Normal Frequency lation Infrequent Bladder neck diurnal enuresis contracture

K. IV[.

F

6 months

0

Yes

Normal

None

J.H.

F

4 weeks

0

No

Normal

Frequent voiding of small volume

Bladder trabecu- Unsuccessful lation Urethral stricture

K.M.

M 20 months

20

No

Normal

Frequent voiding small amount

Bilateral Bladder neck ureteroceles contracture Bladder trabeculation

Pyuria with bacteriuria

I.V.P.

Symptoms in retrospect

Results of cystoscopy and urethral bougienage

Megatrigone

or

more

the salient findings of the one male a n d nine female infants is given in T a b l e IX. I t was interesting to note that with careful search of 10 widely spaced high-power fields (x450), the vast majority of infants have no white blood cells per high-power field. Therefore, we were suspicious of any white blood cells per high-power field. T a b l e V I shows that only 31 of 200 a s y m p t o m a t i c female infants had one or more white cells per highp o w e r field. Persistent p y u r i a occurred at 20

Results o/ voiding cystourethrogram

Not done

Left vesicorenal low pressure reflux

white blood cells per high-power field if persistent bacteriuria was present. O f 200 a s y m p t o m a t i c male infants only 5 h a d any white blood cells per high-power field. T w o had 10 to 20 white blood cells per high-power field. However, these did not persist in subsequent sediments nor did the infants have bacteriuria. T h e one male with persistent bacteriuria a n d u r o p a t h y (K. M.) did not have pyuria. Thus, no male had persistent pyuria.

Volume 65 Number 1

Red blood cells. Female. Of 200 female infants, only 3 had any red blood cells per high-power field. In 2 patients the red blood cells (1 to 2 per high-power field) did not persist beyond the first sediment. The third patient (M. H.) had many red blood cells, persistent bacteriuria, and proved bladder neck contracture. Male. Of the 200 male infants only one had any red blood cells (1 per high-power field). None were seen on repeat examination. Proteinuria. No urine registered 30 mg. or more by the use of the dip stick (Combistix) method. Casts. A pus cast was seen in only one patient (M. P.). Hyaline and granular casts were seen in small numbers in febrile patients and in some with bacteriuria. They were not seen in the spun sediment of the "well" infant. Glucose. No specimen recorded glucose on the dip stick (Combistix) method. Results of urologic study. In the seven patients with bacteriuria, 1 male and 6 females cystoscopy and bougienage were performed. Abnormalities were found in all but one, and all involved the lower urinary tract. These included (Table I X ) trabeculation of the bladder in 5 patients (1 male and 4 female); urethral meatal stenosis, diagnosed by bougienage (3 females); and vesicorenal reflux in 3 females. Two had high pressure voiding reflux, and one, low pressure reflux. Residual urine was not found in any patients. Retrograde pyelography was performed when intravenous pyelograms were adjudged insufficient. No radiographic evidence of renal parenchymal damage was seen in any patient. DISCUSSION An epidemiologic study in the framework of a private practice often suffers the disadvantage of small numbers. However, it simultaneously offers the special advantage of the intensively studied individual. This advantage is especially unique in the age group under study where the patient under 1 year is seen every month and the 1 to 2

Asymptomatic baeteriuria and pyuria

63

year old, quarterly. Each patient on every visit is screened for symptoms and signs and the urine studied. It would be useful to contrast this study epidemiologically with Kunin's 14-1~ study of a school age population in Virginia. His was the study of large numbers of well children at one point in time. Ours was the study of a "known" child, well and unwell, at many points in time. Both types of survey have merit as screening procedures. However, with the intermittent nature of urinary tract infection in mind, 17~~ repeated surveys of the smaller populations might be more fruitful. Reference to Table I X reveals that 4 of 9 female infants would have gone undiagnosed had one screening been relied upon. One male with bacteriuria would likewise have gone undetected. Implicit in the literature is the impression that the prevalence of urinary tract infection in infancy is high, 17' 21, 22 mainly because of the frequent occurrence of congenital genitourinary anomalies and the unique opportunities for ascending infection, especially in the female, afforded by the diapered child?5, 1~-2a If this were true, the need for early and routine surveys in the infant population to establish the presence or absence of infection and to rule out anomalous structural conditions would be obvious and urgent. However, a critical survey of the normal infant population with the use of quantitative culture techniques similar to Kunin's 14-1G study of the healthy school age population and Kass '27 study of the adult population is lacking. Kunin made a single screening of 10,989 healthy children in a school age population for asymptomatic bacteriuria. He found that 1 per cent of the females and 0.026 per cent of the males had bacteriuria. 14 Our figures in an infant population seen in a private pediatric office on a single screening are significantly greater at 2 per cent female and no males. On repeated screening of the same infant population, Table IX, the figures rose to 4.5 per cent female and 0.5 per cent male. We think, because of the intensive repeated screening detailed above, that this actually represents a very reliable figure of incidence for asymptomatic bac-

64

Randolph and Greenfield

teriuria in this infant population. H a d our 400 infants been screened by pyuria alone, bacteriuria would have gone undiagnosed in 4 of 10, an incidence of 60 per cent pyuria with bacteriuria. This is in approximate agreement with Kass' figure in adults ( 3 3 ~ to 50 per cent), and Kunin's for school children (66 per cent).14 As a single screening technique, pyuria had a decided tendency to be intermittent, did not persist in those with fewer than 20 white cells per high-power field, and did not persist at any level in the absence of bacteriuria. In the past a diagnosis of urinary tract infection was largely dependent upon the demonstration of pyuria,~, 20 the urine culture only playing a supporting role since contamination was thought to occur so readily. The quantitative urine culture, of course, has changed all this, separating as it does, contamination from infection. 12 However, the diagnosis of pyuria in terms of cells per high-power field is unclear, TM 2~ particularly at the lower levels where review of the literature would not help one separate a high normal excretion of white blood cells from a low-grade pyuria. The absence of white blood cells from the spun sediment of 95 per cent of the males and 84.5 per cent of the female infants in this series when 10 low- and 10 high-power fields are scanned might cause one to suspect that the presence of any white blood cells per high-power field are significant when studied under these conditions. One might speculate that the definition of pyuria sl~ould concern itself more with the consistent presence of any cells per high-power field rather than to limit itself to a high number in a single specimen. While a study involving a larger number of infants might lend support to this contention, this study does not. Our data show pyuria to be reproducible only at the level of 20 white blood cells per high-power field or higher. It follows then, that as a screening device for pyuria, 0 to 20 white blood cells per high-power field is no better than no white blood cells per high-power field. The presence of one pus cast alerted us to the existence of pyelonephritis in one infant

July 1964

(M. P.). Subsequent specimens showed pyuria and bacteriuria. This is the only patient who had cellular casts. Proteinuria was not seen in any of the patients. Hence, this had no value as a screening procedure in our study. Red blood cells ,were seen in the urines of only 4 infants, 1 male and 3 females. Three had only one to two per high-power field and in only one specimen. One female had many red blood cells per high-power field and proved to have bladder neck contracture on subsequent study. It would seem, apropos of the literature, that any red cells should be regarded as significant until proved otherwise. 2s All patients were asymptomatic from a genitourinary standpoint on initial screening. However, ati but 2 of the ten patients With bacteriuria (80 per cent) were found to have symptoms of lower tract pathology on careful review of symptoms aided by a diary type procedure in which the mother recorded her observations of the child's micturitional pattern (Table II). This in turn agrees wit~ the findings on urologic study in which 6 of the seven patients studied had changes consistent with lower urinary tract obstruction. It follows then, that a careful history relating to symptoms of lower tract obstruction should be part of an efficient screening technique for urinary tract infection in infants. To turn again to Kunin's !arge study of school children, it is noteworthy that 66 per cent of his patients with bacteriuria had symptoms o f lower tract obstruction on close questioning. We find the history far more reliable if it is a written log of observations rather than a mere recollection and verbal report. The absence of infection in the presence of urinary obstruction deserves special note. While well known, it may not be widely appreciated. Thirty per cent of our infected patients, as shown by repeated cultures, developed persistent bacteriuria relatively late in their course in spite of well-established urinary tract pathology. Two other patients who demonstrated bacteriuria only after repeated cultures were lost to follow-up before a urologic study could be accomplished. This

Volume 65 Number 1

intermittent nature of bacteriuria and pyuria, as noted in our study and recognized by others, ~r-z~ illustrates the need for the use of all three methods of screening--the quantitative urinary cultures, the study of the urinary sediment, and the urinary "diary." A good correlation was found between bacteriuria and pyuria (60 per cent), bacteriuria and symptoms of low urinary tract obstruction (80 per cent), and the finding of lower tract pathology on urologic study (86 per cent). We are gratified that the most reliable screening device is also the simplest. T h e loop-surface agar technique is readily adaptable to office and outpatient practice where as a routine procedure bacteriuria m a y be diagnosed early before it becomes a possibly malignant process. 22 We were very pleased with the Pediatric Urine Collector which m a d e the clean specimen readily accessible with a remarkably low rate of contamination, 1 per cent in the female, and 0.5 per cent in t h e male, with minimal or no preparation of the child.

Asymptomatic bacteriuria and pyuria

65

to persist only in the presence of bacteriuria. Proteinuria was not helpful as a screening device. Six females and one male infant with bacteriuria were studied urologically. Six of these seven infants, 86 per cent (5 female and 1 male), showed evidence of lower urinary tract obstruction. Although all infants were carefully screened for symptoms prior to admission to this study, symptoms were recalled in 80 per cent of the infected patients when their parents were informed of laboratory evidence of urinary tract infection. A careful hastory would thus seem to be an important part of an efficient screening method and a urinary "diary" is suggested. T h e quantitative colony count emerges as the most reliable screening method for urinary tract infection. T h e loop-surface agar technique is readily adaptable to office and outpatient department practice where, as a routine method, bacteriuria can be diagnosed early before it m a y become a malignant process.

SUMMARY

While presenting for routine care in a private pediatric practice over a 13 m o n t h per!od, 200 male and 200 female infants were repeatedly surveyed for the presence of asymptomatic bacteriuria and pyuria. T h e clean voided specimen was made accessible by the Pediatric Urine Collector. T h e latter was used on a grossly clean perineum without benefit of special cleansing. Contamination was remarkably low (1 per cent female and 0.5 per cent male). T w o per cent of the female infants and no male infants showed baeteriuria on the initial screening. With repeated survey of the same population the percentage of bacteriuria rose to 4.5 per cent female and 0.5 per cent male. T h e value of repeated screenings is implied in these figures. Pyuria was less reliable as a screening test, being present in 60 per cent of those with bacteriuria. Pyuria on repeated survey was found to be intermittent at all levels, to persist only at the high cell levels (20 white blood cells per high-power field), and

We are grateful to Dr. Robert E. Cooke, Chairman, Department of Pediatrics, Johns Hopkins University for reviewing the manuscript and for his helpful advice, and to John S. Walker, M.D., Department of Clinical Research, The Upjohn Company, Kalamazoo, Mich., for continued support, constant encouragement, and good counsel. Our thanks to Mrs. Patricia Michico for her excellent work in all technical procedures involved in this project.

REFERENCES

1. Burke, J. B.: Pyelonephritis in infancy and childhood, Lancet 2:1116, 1961. 2. Campbell, E. W.: Significance and treatment of urinary tract infections in children, Pennsylvania M. J. 58: 194, 1955. 3. Dock, D. S., and Guze, L. B.: Acute nonobstructive pyelonephritis: Occurrence of bacteriuria after apparent recovery, Ann. Int. Med. 50" 936, 1959. 4. Neumann, C. G., and Pryles, C. V.: Pyelonephritis in infants and children, A. M. A. J. Dis. Child. 104: 215, 1962. 5. Bugbee, H. G., and Wollstein, M.: Surgical

66

6. 7. 8. 9.

10.

11.

12.

13. 14.

15. 16.

Randolph and Greenfield

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