* Detecting urinary tract infection in early
* Suprapubic aspiration of urine is considered
in Britain to be a difficult technique
* This study showed that use of ultrasound
guidance makes suprapubic aspiration in child-
ren and babies easy and safe
* Low bacterial counts were present in the
urine of two fifths of the children with abnor-
malities ofthe urinary tract
* Clinicians should regard low bacterial counts
is important for preventing renal
had vesicoureteric reflux. Secondly, few of the non-
bacteriuric specimens showed pyuria. All the children
from whom these specimens came were being investi-
gated for febrile illnesses. Thus the view that pyuria
often occurs as a non-specific response to fever seems
untenable. Two thirds of the children with sterile
pyuria were neonates, ofwhom many were premature
and many were taking antibiotics; the possibility of
bloodbome urinary tract infection, known to occur in
neonates,"3 is strong. Radiological abnormalities were
found in about a third of the children who were
We suggest that clinicians should always seek an
explanation for sterile pyuria and should consider the
possibility of urinary tract infection if sterile pyuria
We thank Drs G M Lewis, M J Hardman, and E R
Wozniak for permission to include their patients and Veronica
Symes for typing the manuscript.
1 Smellie JM. Reflections on 30 years of treating children with urinary tract
infections.J Urol 1991;146:665-8.
2 Chiu N-C, Huang F-Y, Tsai T-S. Urinary tract infections in children. Acta
3 Airede Al. Urinary tract infections in African neonates. J Infect 1992;25:
4 O'Callaghan C, McDougall PN. Successful suprapubic aspiration of urine.
Arch Dis Child 1987;62:1072-3.
5 Austin N, Maskell R, Hallett RJ. Diagnosis of urinary tract infection in
children. Lancet 1992;339:65.
6 Maskell R. Urinary tract infection. London: Edward Arnold, 1982:24.
7 Smellie JM. Medical aspects of urinary infection in children. J R Coil
Physicians Lond 1967;l:189-96.
8 Ahmad T, Vickers D, Campbell S, Coulthard MG, Pedler S. Urine collection
from disposable nappies. Lancet 1991;338:674-6.
9 Lee P, Verrier Jones K. Urinary tract infections in febrile convulsions. Arch
Dis Child 1991;66:1287-90.
10 Kellogg JA, Manzella JP, Shaffer SN, Schwartz BB. Clinical relevance of
culture versus screens for detection of microbial pathogens in urine
specimens. AmJMed 1987;83:739-44.
11 Powell HR, McCredie DA, Ritchie MA. Urinary nitrite in symptomatic and
asymptomatic urinary infection. Arch Dis Child 1987;62:138-40.
12 Woodward MN, Griffiths DM. Use of dipsticks for routine analysis of urine
from children with acute abdominal pain. BMJ 1993;306:1512.
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(Accepted 12November 1993)
Erika von Mutius,
Center, Department of
Pediatrics, University of
Arizona, Tucson, Arizona,
Femando D Martinez,
Research Centre for
Health, Medis Institute,
Peter Reitmeir, statistician
Hospital, Halle, Germany
Correspondence and reprint
Lindwurmstr 4, D-8000
Munchen 2, Germany.
Skin test reactivity and number ofsiblings
Erika von Mutius, Fernando D Martinez, Christian Fritzsch, Thomas Nicolai, Peter Reitmeir,
Objective-To investigate the relation between
Design-Cross sectional survey among school-
children aged 9-11 years. Skin prick tests in the
children andselfcompletion ofwritten questionnaire
Subjects-5030 children in Munich and 2623
children in Leipzigand Halle, Germany.
Main outcome measures-Atopic status assessed
by skin prick tests.
controlled for, the prevalence ofatopic sensitisation
(odds ratio=0-96 for one sibling, 067 for five ormore
siblings; P=0005). In atopic children the severity of
the skin test reaction as assessed by the weal size
was not associated with the number ofsiblings.
Conclusions-Factors directly orindirectly related
to the number of siblings may decrease the sus-
ceptbility of children to become atopic. Thus,
declining family size may in part contribute to the
increased prevalence of atopic diseases reported in
Western countries overthe past few decades.
A strong inverse association between the number of
siblings and the prevalence of hay fever in British
children was reported by Strachan.1 As the presence of
older siblings had a stronger effect than the presence of
younger siblings, the author suggested that factors
such as viral infections early in life may prevent the
development of allergic sensitisation. His observations,
however, were based on parents' answers to a question-
naire. It could be argued that the effects observed may
have been affected by recall bias, as parents with many
children may not remember a relatively mild disease
such a hay fever as accurately as parents with only one
or two children.
The aim of this report was to investigate the relation
between the number of siblings and an objective
measure of atopic sensitisation in children living in
eastern and western Germany. We performed skin
prick tests in 9-1 1 year old schoolchildren in a survey in
Leipzig and Halle, East Germany, and Munich, West
Germany, and related these findings to answers
to a parental questionnaire on household size, socio-
economic status, and occurrence ofdisease.
STUDY AREAS AND POPULATIONS
In former West Germany, all fourth grade pupils
(n=7445) at all primary schools in Munich, a city of
about 1-3 million inhabitants located in the south-
western part of the country, were included in the
study. All schoolchildren (n=3105)
fourth grade of a random sample of 39 schools in
Leipzig and of 23 schools in Halle were studied in
former East Germany. Leipzig, a city of about 535 000
inhabitants, is located in the southeastern part of the
country in close proximity (35 km) to Halle, a city of
about 300 000 inhabitants. These two cities are heavily
polluted due to private coal burning and industrial
emissions, whereas Munich has moderate industry but
BMJ VOLUME 308
12 MARCH 1994