Daniel Cohen1 and Ranan Dasgupta2
Department of Urology, Imperial College London, London, UK
Department of Urology, Imperial College Healthcare NHS Trust, St Mary’s Hospital, Praed Street, London, W2 1NY, UK
Pregnancy poses its own specific problems with regard to urinary infections, in terms of both treatment and prophylaxis. Certain antibiotics are safe in certain trimesters, and there is also evidence for the use of antibiotics in the management of asymptomatic bacteriuria during pregnancy, particularly to reduce the frequency of pyelonephritis and its sequelae.
Similarly the treatment of UTIs in childhood presents different challenges, particularly as the sequelae of this can present later in adulthood, and there are conditions such as phimosis and vesicoureteric reflux, the timing of the treatment of which can lead to controversies in management. Specialist care is recommended in these cases, and close follow-up through adolescence into adulthood would be beneficial.
Part I: UTI in Pregnancy
How Common Are UTIs During Pregnancy?
UTIs are the most common bacterial infections in pregnancy. Asymptomatic bacteriuria complicates between 4 and 10 % of all pregnancies. Up to 4 % of women will develop an acute cystitis during pregnancy, and 1–2 % will develop acute pyelonephritis, most commonly in the third trimester. This incidence is significantly higher than in the nonpregnant population.
Women with a previous history of UTIs, urinary tract abnormalities, and diabetes have an increased risk. There is also some evidence that women of lower socioeconomic class have higher rates of infection. There is a consensus view that pregnant women should be screened for bacteriuria at least once in the first trimester.
Why Are Urinary Tract Infections Common in Pregnancy?
The anatomical and physiological changes that occur during pregnancy predispose to urinary tract infection.
Progesterone-mediated smooth muscle ureteric relaxation may lead to dilatation of the upper urinary tracts; mechanical extrinsic compression of the ureters by the enlarging uterus can also produce a physiological hydroureter and hydronephrosis. The enlarged uterus can also displace the bladder superiorly and anteriorly, which may contribute to impaired bladder emptying, thereby urinary stasis and possible UTI. Finally the renal blood flow and thus the glomerular filtration rate increase by 30–40 % during pregnancy, causing enlargement and hyperemia of the kidney.
Should Asymptomatic Bacteriuria in Pregnancy Be Treated?
Yes. Studies have shown that 20–40 % of pregnant women with asymptomatic bacteriuria develop pyelonephritis during pregnancy. There is also associated significant increase in the number of low-birth-weight infants, low gestational age, and neonatal mortality.
Epidemiological evidence points to a decreased rate of pyelonephritis in pregnancy since asymptomatic bacteriuria screening became routine. In the 1970s, before screening became routine, there was a 3–4 % rate of pyelonephritis in pregnancy, compared with an incidence of 1.4 % in 2001.
A recent Cochrane review meta-analysis of trials comparing antibiotics versus no treatment for asymptomatic bacteriuria showed a substantially decreased risk of developing acute pyelonephritis.
What Are the Consequences of Not Treating a UTI in Pregnancy?
There are potential serious consequences for both mother and fetus of leaving a UTI untreated during pregnancy. Women with persistent infection despite treatment are at higher risk of delivering premature infants and development of anemia. If the UTI results in pyelonephritis, this may have the consequences listed above.
What Duration of Antibiotics Is Recommended for a UTI in Pregnancy?
Treatment of any UTI should depend on the likely antibiotic sensitivities according to local treatment guidelines.
In asymptomatic bacteriuria, there is no clear consensus as to the optimal duration of treatment. A Cochrane review analyzed studies comparing single-dose treatment with 4–7-day courses of antibiotics. There was no significant statistical difference in treatment effectiveness between the groups nor was there a conclusion as to which treatment regime was preferable.
Most symptomatic UTIs in pregnancy present as acute cystitis. A 7-day course of oral antibiotics is widely recommended, although some centers do prescribe shorter courses. Recurrent infections may be managed safely by low dose daily prophylaxis, for example, with cephalexin or nitrofurantoin.
Acute pyelonephritis has potentially serious consequences, and admission to hospital for intravenous antibiotics is recommended, although this may be converted to oral therapy after 48 h if the patient is afebrile. Initial treatment with a cephalosporin or co-amoxiclav plus aminoglycoside is recommended. A course of 10–14 days should be completed.
Which Antibiotics Should Be Avoided During Pregnancy?
Trimethoprim, a folate antagonist, has a risk of teratogenicity and should be avoided in the first trimester. Sulphonamides (risk of neonatal hemolysis and methemoglobinemia) and chloramphenicol should be avoided in the last trimester. Quinolones (e.g., ciprofloxacin) may cause arthropathy, and tetracyclines can cause dental discoloration and may also cause skeletal abnormalities. Neither should be prescribed during pregnancy (BNF).
Part II: UTI in Children
With What Signs and Symptoms Might a Child with a UTI Present?
Features of a UTI in a child may be very nonspecific. A child with an unexplained fever of over 38 °C should be tested for a UTI.
The presenting signs and symptoms vary depending on the age of the child. The most common presenting sign is a fever. Table 3.1 illustrates the variation in signs and symptoms of UTI.
Symptoms and signs in infants and children with UTI
How Can Urine Be Collected from Children?
Ideally a clean-catch specimen will be collected. If this is difficult, a urine collection pad can be tried. It is recommended that suprapubic aspiration should only be performed under ultrasound guidance.
If no urine can be obtained, the NICE guidelines recommend that treatment of a suspected UTI should not be delayed if there is high clinical suspicion and the child is at risk of serious illness.
How Does the Age of the Child Affect the Treatment Pathway?
The age of the child is crucial in determining their optimal management.
A child under 3 months with a suspected UTI should be immediately referred to pediatric specialist care. A urine sample must be sent for urgent microscopy and culture.
A child between the ages of 3 months and 3 years should also have urine sent off for urgent microscopy and culture. If the child has urinary tract symptoms, it is appropriate to commence antibiotic treatment while waiting for a result. However, if the child has nonspecific UTI symptoms, acute management depends on the severity of illness.
The risk of developing serious illness can be classified according to the following table suggested by NICE (Table 3.2):
Traffic light system for identifying the risk of serious illness
If a child is deemed to be low risk, the urine should be sent for microscopy and culture. Treatment should commence only if cultures are positive.
Intermediate-risk patients may be referred immediately to a pediatric specialist if the situation demands. Alternatively, urgent microscopy and culture can be arranged, and treatment commenced on the basis of this result. If there is no facility for immediate urine microscopy, the urine may be dipstick tested; antibiotics should be started if nitrites are present.
A high-risk patient should be referred immediately to a pediatric specialist. In all cases, however, urine should be sent for microscopy and culture if the child can produce a specimen.
Does Presence of Leucocytes on Dipstick Require Treatment as for a UTI?
In the absence of bacteria, leucocytes are only significant if the child has urinary tract symptoms. In this case, treatment should be initiated. Symptomatic bacteriuria always indicates a UTI and should be treated appropriately.
How Can an Upper Tract Infection/Pyelonephritis Be Differentiated from a Lower Tract Infection/Cystitis? What Treatment Is Necessary?
A bacteriuric infant or child with a temperature of greater than 38 °C and/or loin pain should be regarded as having an upper tract infection. These patients should be referred acutely to a pediatric specialist if they are deemed high risk or under 3 months of age. Otherwise, a course of low-resistance oral antibiotics for 7–10 days is recommended (e.g., a cephalosporin or co-amoxiclav).
It is recommended that lower urinary tract infections in children over 3 months are treated for 3 days with oral antibiotics. If the child remains unwell after 24–48 h, the diagnosis should be reconsidered. Antibiotic treatment should be in line with local microbiological guidance.
Which Patients with UTIs Should Undergo Acute Renal Tract Imaging?
Any infant or child with features of an atypical UTI should undergo a urinary tract ultrasound scan at the time of acute infection.
Features of an atypical UTI are one or more of:
· Abdominal or bladder mass
· Raised creatinine
· Poor urine flow
· Pathogen other than E. coli isolated (can wait until 6 weeks for imaging if clinically well)
· Failure to respond to antibiotics within 48 h
In addition, all infants under 6 months with a first-time UTI should have an ultrasound scan of the urinary tract within 6 weeks. An infant or child with a documented atypical UTI should be referred to a local pediatric unit for consideration of a dimercaptosuccinic acid (DMSA) radionuclide scan and/or micturating cystourethrogram (MCUG).
How Is a Recurrent UTI Defined? What Investigations to These Patients Need?
A recurrent UTI is defined as either:
· Two or more upper tract infections/pyelonephritis
· One upper tract infection/pyelonephritis plus one lower tract infection/cystitis
· Three or more lower tract infections/cystitis
All infants and children with recurrent UTI require DMSA scanning, and those under 6 months require a MCUG. Infants with recurrent UTI should be assessed by a pediatric specialist. Recurrent UTI can result in renal scarring, progressive renal disease, and pyelonephritis.
How Common Are UTIs?
Around 8–10 % of girls and 1–3 % of boys will have had a UTI by the age of 16. Boys are affected much more commonly in the first year of life, after which the incidence falls significantly. Girls however have a higher risk of developing a UTI after the first year.
Is It True That Uncircumcised Male Infants Have a Higher Risk of Developing a UTI?
Circumcision appears to reduce the likelihood of developing a UTI by tenfold. A large meta-analysis concluded that 111 neonates being circumcised prevent one UTI in healthy males. In boys with recurrent UTI or high-grade vesicoureteric reflux, the risk of UTI recurrence is 10 and 30 % and the numbers needed to treat are 11 and 4, respectively.
Part I: UTI in Pregnancy
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Part II: UTI in Children
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National Institute for Health and Clinical Excellence. Feverish illness in children – assessment and initial management in children younger than 5 years CG47. London: National Institute for Health and Clinical Excellence; 2007b.
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Singh-Grewal D, Macdessi J, Craig J. Circumcision for the prevention of urinary tract infection in boys: a systematic review of randomised trials and observational studies. Arch Dis Child. 2005;90(8):853–8.PubMedCrossRef