• Convey a positive approach and reassure the woman that treatment with an antibiotic will prevent any harm to her baby, and will shorten the duration of symptoms.
• If the women has fever or loin tenderness, suspect upper urinary tract infection and admit or seek urgent specialist opinion.
• Offer paracetamol for symptomatic relief. Do not recommend urine alkalinizing agents or cranberry products.
• Send a urine sample for culture before starting antibiotic treatment.
• Prescribe an antibiotic empirically. If local guidelines are not available, suitable first-line antibiotics are (in order of preference):
• Nitrofurantoin 50 mg four times daily, or 100 mg (modified-release) twice daily, for 7 days.
• Trimethoprim 200 mg twice daily, for 7 days (if the woman is not folate deficient or taking a folate antagonist, and has not been treated with trimethoprim in the past year).
• Cefalexin 500 mg twice daily, or 250 mg 6-hourly, for 7 days.
• Follow up after 48 hours (or according to the clinical situation) to check response to treatment and the urine culture results.
• Amoxicillin 250 mg three times daily, for 7 days, is recommended only if the organism is reported to be susceptible on the culture results.

Sending urine for culture

• The recommendation to send urine for culture before starting treatment is pragmatic [SIGN, 2006]. The results can confirm the diagnosis and guide further treatment, especially if the uropathogen turns out to be resistant to the empirically chosen antibiotic.

Relieving symptoms with paracetamol

• The recommendation to relieve symptoms with paracetamol is pragmatic.
• Paracetamol is preferred over ibuprofen because it can be used all stages of pregnancy. For further information, see Choice in pregnancy or breastfeeding for analgesics and antipyretics.

Treating infection with an antibiotic

• Treatment with an antibiotic is recommended because there is good evidence from placebo-controlled trials in non-pregnant women with cystitis that antibiotics cure the infection, and experts suggest that urinary tract infection in pregnancy may increase the risk of fetal death, and, in the infant, increase the risks of developmental delay and cerebral palsy [Foxman, 2002; European Association of Urology, 2009].
• CKS did not recommend that women who have mild symptoms should be offered the option of waiting for the urine culture results before starting antibiotic treatment, although this option is recommended for women who are not pregnant. CKS made no recommendation because no evidence and no published expert opinion was found on this strategy.

Choosing antibiotics for empirical treatment

• The choice of antibiotic for empirical treatment should take into account local rates of resistance in uropathogens, and the safety, tolerability, and cost of antibiotic options [SIGN, 2006].
• For empirical treatment, nitrofurantoin is preferred over trimethoprim because:
• Nitrofurantoin has been used extensively since the 1950s and its safety profile in human pregnancy has been well documented [Goldshield Pharmaceuticals, 2002b; Goldshield Pharmaceuticals, 2007].
• Although the evidence on nitrofurantoin for treating symptomatic urinary tract infections (UTIs) in pregnant women is poor (only one small study was identified — none were found on trimethoprim), there is indirect evidence from a Cochrane systematic review and a large multicentre trial (undertaken by the World Health Organization [WHO], n = 778) supporting its efficacy and safety profiles for asymptomatic bacteriuria in pregnancy. For further information, see Screening for and managing asymptomatic bacteriuria in pregnancy.
• Although trimethoprim is commonly used to treat symptomatic UTIs, good evidence to support its use in pregnancy is lacking. In addition, a recent survey found that women's dietary intake of iron, vitamin D, calcium, and folate remain below recommended levels [Ruxton and Derbyshire, 2010].
• Cefalexin is less preferred because:
• Although the safety profile is well documented in pregnancy, the Health Protection Agency recommends avoiding the use of broad spectrum antibiotics (such as cephalosporins) when narrow spectrum antibiotics remain effective [HPA, 2009].
• There are concerns that broad spectrum antibiotics increase the risk of Clostridium difficile, meticillin-resistant Staphylococcus aureus (MRSA), and resistant UTIs.
• C. difficile infection can be life-threatening in pregnant women, and there are case-reports of both maternal deaths and stillborn infants [Rouphael et al, 2008].
• Amoxicillin is not recommended for empirical treatment because:
• There is evidence from several urine culture studies that resistance to amoxicillin is higher than for trimethoprim.

Duration of antibiotic treatment

• Evidence on different antibiotic regimens for treating symptomatic UTIs in pregnant women is lacking.
• Given the possible increased risk of fetal complications with a UTI, a 7-day course of antibiotics is preferred over shorter courses. This is extrapolated from indirect evidence which found a higher bacteriological cure with longer antibiotic regimens.
• For women with acute uncomplicated UTI who are not pregnant, a Cochrane systematic review found a 5–10-day course produced a higher bacteriological cure (but more adverse effects) than a 3-day course. The authors concluded that a 5–10 day regimen may be considered for women in whom eradication of bacteriuria is important.
• A recent large WHO study found a higher cure rate with a 7-day course of nitrofurantoin (86%) than a 1-day regimen (76%) in pregnant women with asymptomatic bacteriuria [Lumbiganon et al, 2009]. Adverse effects were not statistically different between the two groups.
• A 7-day course is supported by guidance issued by the European Association of Urology (no evidence provided) [European Association of Urology, 2009].

Following up to ensure eradication of infection

• Following up to ensure eradication of infection is based on expert opinion [SIGN, 2006].
• Subsequent screening for asymptomatic bacteriuria at antenatal visits is a pragmatic recommendation.

Managing incidentally-found group B streptococcus infection

• The antenatal care service should be informed when a group B streptococcus (GBS), Streptococcus agalactiae, is isolated from urine. GBS bacteriuria, even if treated, may be associated with increased risk of neonatal GBS disease, and so antibiotic prophylaxis should be offered to the mother during delivery. This recommendation is based on expert opinion in guidelines from the Royal College of Obstetricians and Gynaecologists [RCOG, 2003].