Pyelonephritis is more common in pregnancy, likely due to the increased risk for recurrent, asymptomatic bacteriuria and physiologic maternal immunosuppression. In addition, progesterone-induced ureteral dilation, ureteral valve laxity, and bladder compression from the gravid uterus may facilitate bacterial ascent from the lower urinary tract.
| Risk factors | • Asymptomatic bacteriuria • Diabetes mellitus • Age <20 | | --- | --- | | Common pathogens | • Escherichia coli (most common) (70%) • Klebsiella • Enterobacter • Group B Streptococcus | | Complications | • Preterm labor • Low birth weight • Acute respiratory distress syndrome | | Treatment | • Inhospital Intravenous antibiotics(eg, ceftriaxone) • Supportive therapy • Urine culture and sensitivity |
Patients with pyelonephritis can have preceding symptoms of cystitis (eg, dysuria) followed by fever, chills, back pain, maternal and fetal tachycardia
On examination, costovertebral angle tenderness (the angle created between the 12th rib and the spine) or flank pain is common due to retroperitoneal inflammation of the kidney.
Retroperitoneal inflammation can also extend to the abdominopelvic cavity. This can cause obstetric symptoms, such as uterine irritability (eg, nonpainful contractions, as seen in this patient), that can progress to preterm labor (ie, painful contractions with cervical dilation). Severe pyelonephritis can also cause maternal sepsis, acute respiratory distress syndrome, and fetal compromise (eg, premature birth, low birth weight).
Diagnosis is confirmed with urinalysis (eg, leukocyte esterase, blood), as in this patient. Urine culture is also performed.
Pregnant patients with pyelonephritis are at high risk for severe maternal (eg, sepsis, acute respiratory distress syndrome, preterm labor) and fetal(eg, preterm birth) complications. Therefore, these patients require inpatient admission and empiric intravenous antibiotics (eg, ceftriaxone) while urine culture results are pending. Once patients remain afebrile for 24-48 hours and have symptomatic improvement, they may be transitioned to oral antibiotics based on urine culture results and antibiotic sensitivity testing
Treatment course for pyelonephritis (regardless of pregnancy status) typically requires 5-14 days to completely eliminate bacteria from both the upper (eg, kidney, renal collecting ducts) and lower urinary tract. Following initial treatment with broad-spectrum antibiotics, patients who show clinical improvement (ie, no fever for 48 hours) are typically at low risk for disease progression and/or complications (eg, renal abscess); therefore, these patients can transition to oral antibiotics to complete the treatment course.
The choice of oral antibiotic during pregnancy is guided by fetal safety profile and urine culture sensitivity testing. In general, oral antibiotics to complete treatment are limited to beta-lactam medications (eg, cephalosporins, penicillins), which are safe during all trimesters. Therefore, the most appropriate therapy for this patient with cephalexin-sensitive E coli is oral cephalexin. Following completion of treatment, pregnant patients also require a repeat urine culture (due to a high risk for persistent bacteriuria) and daily antibiotic prophylaxis (eg, cephalexin) for the remainder of the pregnancy to prevent recurrence.
(Choice B) Ciprofloxacin, a fluoroquinolone, can be used to treat acute complicated urinary tract infections in nonpregnant patients; however, it is generally avoided during pregnancy because its fetal effects are not well studied. In addition, this patient's urine culture shows resistance to ciprofloxacin.
(Choices C and E) Nitrofurantoin and trimethoprim-sulfamethoxazole are commonly used to treat acute cystitis during pregnancy; however, nitrofurantoin achieves poor concentration in the kidneys and is therefore inadequate for the complete treatment of pyelonephritis. Trimethoprim-sulfamethoxazole is generally avoided in the third trimester because of the risk for neonatal kernicterus, making it a poor choice for this patient (34 weeks gestation).