How is pyelonephritis prevented and treated in pregnant women?
Pregnant women are screened for bacteriuria by urine culture in early pregnancy.
Asymptomatic women with a positive urine culture (≥10 5 CFU/mL of a single gram-negative organism on two or more consecutive urine cultures) or women with symptomatic infection at any time are treated and then screened for recurrent bacteriuria, usually monthly, for the duration of the pregnancy.
If a second episode of urinary infection occurs, prophylactic antimicrobial therapy is given until the end of the pregnancy. The preferred regimen is a beta-lactam antibiotic, which is safe for the fetus. Nitrofurantoin is also safe and effective. TMP/SMX is avoided because of a small but well-documented association with fetal abnormalities when given in the first trimester, and fluoroquinolone antimicrobials are contraindicated because of potential detrimental effects on fetal cartilage. For prophylactic therapy, either cephalexin 500 mg or nitrofurantoin 50 or 100 mg daily are recommended.
A pregnant woman who presents with pyelonephritis should be hospitalized for initial management. The recommended empiric regimen is ceftriaxone 1 to 2 g once daily. A carbapenem or aminoglycoside, usually gentamicin, may be used if there is antimicrobial resistance or patient intolerance to ceftriaxone.
