MKSAP Quiz: Screening urine culture grows E. coli
This week's quiz asks readers to evaluate a 65-year-old woman whose insurance policy screening reveals Escherichia coli.
A 65-year-old woman is evaluated because a screening urine culture for an insurance policy grows greater than 105 colony-forming units/mL of Escherichia coli. She does not have fever, dysuria, urinary frequency, or other symptoms. Medical history is unremarkable. She has no allergies and takes no medications. Physical examination findings are normal.
Which of the following is the most appropriate treatment?
A. Amoxicillin
B. Ciprofloxacin
C. Trimethoprim-sulfamethoxazole
D. No treatment
MKSAP Answer and Critique
The correct answer is D) No treatment. This item is available to MKSAP 15 subscribers as item 15 in the Infectious Diseases section. More information about MKSAP 15 is available online.
This patient requires no treatment with antibiotics even if a urinalysis indicates pyuria. Asymptomatic bacteriuria does not cause symptoms of a urinary tract infection but is detected when the results of a urine culture grow greater than 105 colony-forming units/mL. This condition is not uncommon, especially among adult women and the elderly, and rarely requires treatment. Screening for asymptomatic bacteriuria is generally recommended before transurethral resection of the prostate, urinary tract instrumentation involving biopsy, or other tissue trauma resulting in mucosal bleeding. Screening is not recommended for simple catheter placement or cystoscopy without biopsy or in most asymptomatic ambulatory patients. Pregnant women are screened for asymptomatic bacteriuria, which is associated with low birth weight and prematurity.
Asymptomatic bacteriuria is only treated in the following circumstances: in pregnant women, in patients who recently had an indwelling catheter removed, before an invasive urologic procedure, in neutropenic patients, or in patients with a urinary tract obstruction. Chronic prophylactic antibiotic therapy is beneficial in pregnant women with recurrent asymptomatic bacteriuria; if untreated, 20% to 40% of patients will progress to symptomatic urinary tract infection, including pyelonephritis.
Key Point
- Although asymptomatic bacteriuria in adult patients usually does not require treatment, pregnant women should be treated to decrease the risk of pyelonephritis.