What is the management of a pregnant female with asymptomatic Escherichia coli (E. coli) bacteriuria?

From the Guidelines

For a pregnant female with asymptomatic bacteriuria due to E. coli, treatment is recommended with a 3-7 day course of antibiotics. First-line options include nitrofurantoin 100mg twice daily (avoid near term), amoxicillin-clavulanate 500/125mg twice daily, or cephalexin 500mg four times daily. Trimethoprim-sulfamethoxazole can be used in the second trimester but should be avoided in the first and third trimesters. Treatment is necessary even without symptoms because asymptomatic bacteriuria in pregnancy increases the risk of developing pyelonephritis, preterm birth, and low birth weight, as supported by the Infectious Diseases Society of America guidelines 1.

Key Considerations

• The Infectious Diseases Society of America recommends screening pregnant women for asymptomatic bacteriuria with a urine culture at least once in early pregnancy 1.
• The U.S. Preventive Services Task Force also recommends screening pregnant women for asymptomatic bacteriuria, as it reduces the incidence of symptomatic maternal urinary tract infections and low birth weight 1.
• After treatment, a follow-up urine culture should be obtained to confirm clearance of the infection.
• Monthly urine cultures throughout pregnancy are recommended to monitor for recurrence.
• If recurrent infections occur, suppressive antibiotic therapy may be considered.
• The choice of antibiotic should be guided by susceptibility testing when available, and patients should be encouraged to stay well-hydrated throughout pregnancy.

Management Approach

• Treatment should be initiated promptly to prevent complications such as pyelonephritis and preterm birth.
• Antibiotic selection should be based on susceptibility testing and safety during pregnancy.
• Follow-up care is essential to ensure clearance of the infection and monitor for recurrence.

From the FDA Drug Label

Genitourinary tract infections, including acute prostatitis, caused by Escherichia coli, Proteus mirabilis, and Klebsiella pneumoniae The management of a pregnant female with E. coli in urine with no symptoms is treatment of the genitourinary tract infection.

• The drug label indicates that Cephalexin is effective against E. coli, which is the causative organism in this case.
• However, it is essential to note that culture and susceptibility tests should be initiated prior to and during therapy to ensure the effectiveness of the treatment.
• Additionally, renal function studies should be performed when indicated.
• The treatment should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria 2

From the Research

Management of Asymptomatic E. coli in Urine in Pregnant Women

• The management of asymptomatic E. coli in urine in pregnant women is crucial to prevent potential complications, such as pyelonephritis and preterm labor 3, 4.
• According to the study by 3, nitrofurantoin is an effective oral agent for the treatment of E. coli infections, with a high susceptibility rate of 87.1% and 88.7% in patients with sporadic and recurrent UTIs, respectively.
• Another study by 4 found that E. coli isolates showed high rates of resistance to erythromycin, amoxicillin, and tetracycline, but high sensitivity rates to nitrofurantoin (96.4%), norfloxacin (90.6%), gentamicin (79.6%), and ciprofloxacin.
• The study by 5 also found that nitrofurantoin retains antimicrobial activity against multidrug-resistant urinary E. coli from US outpatients, with resistance to nitrofurantoin observed in only 2.1%, 7.5%, and 24.1% of isolates resistant to three, four, or five antimicrobial agents, respectively.

Antibiotic Resistance and Treatment Options

• The increasing rates of antimicrobial resistance among E. coli are a growing concern worldwide 6, 7.
• The study by 6 found that cefixime and amoxicillin/clavulanate combination therapy could be an effective oral outpatient treatment option for ESBL-EC.
• However, the study by 7 found that amoxicillin prescribing was positively associated with amoxicillin and ciprofloxacin resistance, while nitrofurantoin prescribing was associated with lower levels of resistance to amoxicillin.
• The choice of antibiotic should be based on the susceptibility profile of the E. coli isolate and the patient's clinical condition, as well as the potential for antibiotic resistance 3, 4, 5.