670
U N I T 7
Kidney and Urinary Tract Function
tissues into the bladder. The most common pathogen
is
Escherichia coli
, followed by
Klebsiella
and
Proteus
species. In uncircumcised boys, the bacterial pathogens
arise from the flora beneath the prepuce. In girls, UTIs
often occur at the onset of toilet training because of uri-
nation dysfunction that occurs at that age.
49
The child
is trying to retain urine to stay dry, yet the bladder may
produce uninhibited contractions, forcing urine out.
The result may be high-pressure, turbulent urine flow or
incomplete bladder emptying, both of which predispose
to bacteriuria. Similar problems can occur in school-
age children who refuse to use the school bathroom.
49
Constipation may increase the risk of UTI recurrence
in children with VUR by compressing the bladder and
bladder neck, resulting in increased bladder storage
pressure and incomplete bladder emptying.
50
Unlike adults, children frequently do not present with
the typical signs of a UTI.
47–51
Many neonates with UTIs
have bacteremia and may show signs and symptoms of
septicemia, including fever, hypothermia, apneic spells,
poor skin perfusion, abdominal distention, diarrhea,
vomiting, lethargy, and irritability. Older infants may
present with feeding problems, failure to thrive, diarrhea,
vomiting, fever, and foul-smelling urine. Toddlers often
present with abdominal pain, vomiting, diarrhea, abnor-
mal voiding patterns, foul-smelling urine, fever, and poor
growth. In older children with lower UTIs, the classic
features—enuresis, frequency, dysuria, and suprapubic
discomfort—are more common. Fever is a common sign
of UTI in children, and the possibility of UTI should be
considered in any child with unexplained fever.
Diagnosis is based on a careful history of voiding
patterns and symptomatology; physical examination to
determine fever, hypertension, abdominal or suprapubic
tenderness, and other manifestations of UTI; and uri-
nalysis to determine bacteriuria, pyuria, proteinuria, and
hematuria. A positive urine culture that is obtained cor-
rectly is essential for the diagnosis.
47–51
Additional diag-
nostic methods may be needed to determine the cause of
the disorder. Childrenwith a relatively uncomplicated first
UTI may turn out to have significant reflux. Therefore,
even a single documented UTI in a child requires careful
diagnosis. Urinary symptoms in the absence of bacteri-
uria suggest vaginitis, urethritis, sexual molestation, the
use of irritating bubble baths, pinworms, or viral cystitis.
In adolescent girls, a history of dysuria, and vaginal dis-
charge make vaginitis or vulvitis a consideration.
49
The approach to treatment is based on the clinical
severity of the infection, the site of infection (i.e., lower
versus upper urinary tract), the risk for sepsis, and the
presence of structural abnormalities. The immediate
treatment of infants and young children is essential.
Most infants with symptomatic UTIs and many children
with clinical evidence of acute upper UTIs require hospi-
talization, rehydration, and intravenous antibiotic ther-
apy.
50,51
Follow-up is essential for children with febrile
UTIs to ensure resolution of the infection. Follow-up
urine cultures often are done at the end of treatment.
Imaging studies often are recommended for children
after their first UTI to detect renal scarring, vesicoure-
teral reflux, or other abnormalities.
UrinaryTract Infections in the Elderly
Urinary tract infections are relatively common in elderly
persons.
43,52,53
They are the second most common form
of infection, after respiratory tract infections, among
otherwise healthy community-dwelling elderly. They are
particularly prevalent in elderly persons living in nurs-
ing homes or extended care facilities.
52
Most of these infections follow invasion of the uri-
nary tract by the ascending route. Several factors pre-
dispose elderly persons to UTIs, including underlying
genitourinary abnormalities, immobility resulting in
poor bladder emptying, diminished bactericidal proper-
ties of the urine, and constipation. Prostatic hyperplasia
with bladder outflow obstruction is the most important
contributing factor in older men, while alteration in the
bacterial flora of the vagina is the most important con-
tributing factor in older women. Added to these risks
are other health problems that necessitate catheteriza-
tion or instrumentation of the urinary tract.
Elderly persons with bacteriuria have varying symp-
toms, ranging from the absence of symptoms to the
presence of typical UTI symptoms. Even when symp-
toms of lower UTIs are present, they may be difficult
to interpret because elderly persons without UTIs com-
monly experience urgency, frequency, and incontinence.
Alternatively, elderly persons may have vague symptoms
such as anorexia, fatigue, weakness, or change in mental
status. Even with more serious upper UTIs (e.g., pyelo-
nephritis), the classic signs of infection such as fever,
chills, flank pain, and tenderness may be altered or
absent. Sometimes, no symptoms occur until the infec-
tion is far advanced.
Interstitial Cystitis/Painful Bladder
Syndrome
Interstitial cystitis or painful bladder syndrome is a
chronic, often debilitating, condition that is character-
ized by urinary frequency, urgency, and severe suprapu-
bic pain.
54–56
Unlike bladder inflammation caused by a
bacterial infection, the condition occurs in the absence
of other pathology. Although previously reported to be
a disorder of middle-aged women, it is now known that
the condition affects both men and women of all ages.
Although the pathophysiology of interstitial cystitis/
painful bladder syndrome is incompletely understood,
it is thought to involve permeability changes of the uro-
thelium, along with mast cell activation and neurogenic
inflammation. Damage to the protective mucosal lining
leads to impaired urothelial cell-barrier function, allowing
urinary solutes to penetrate the epithelium and activate
sensory nerve endings, leading to pain and inflammation.
At present there are no definitive diagnostic tests for
interstitial cystitis/painful bladder syndrome. Diagnostic
steps involve ruling out other diseases and overlap-
ping syndromes. Although not universally accepted,
the potassium sensitivity test is widely used to aid in
the diagnosis. The test involves the instillation of a
