Toxoplasma gondii infection is a protozoan infection to which most adults have antibody protection. When immunocompetent adults do become infected, they are usually asymptomatic or experience only mild constitutional symptoms and lymphadenopathy. Primary infection during pregnancy, however, can have serious consequences for the fetus, including seizures, hydrocephaly, microcephaly, jaundice, chorioretinitis, increased risk of prematurity, and low birth weight. The most severe cases of congenital toxoplasmosis are seen in fetuses infected early in gestation. There can be a 60% reduction in the rate of complications if treatment is instituted. When primary infection is recognized after 14 weeks’ gestation, treatment with pyrimethamine and sulfadiazine along with leucovorin should be started. The safety of these medications before 14 weeks’ gestation has not been demonstrated. Prevention remains the goal, and pregnant women should be instructed to avoid potential sources of exposure, such as undercooked meat and cat feces.

Urinary Tract Infections

Pregnant women are predisposed to infections of the urinary tract because of dilation of the ureters and collecting systems, smooth muscle relaxation caused by increased progesterone concentrations, and glycosuria.

Between 5% and 10% of pregnant women have asymptomatic bacteriuria. If untreated, up to 40% of these women suffer acute pyelonephritis during pregnancy or the puerperium. Acute pyelonephritis is more severe in pregnant women and is associated with maternal complications as well as increased preterm labor and low birth weight. Screening urine cultures in all women during early gestation, with appropriate treatment and follow-up, minimizes the occurrence of significant infection during the third trimester. Patients with treated bacteriuria or a history of frequent urinary tract infections may need to be screened more frequently. Treatment of asymptomatic bacteriuria can be accomplished with ampicillin or nitrofurantoin. Quinolones are contraindicated. A 7- to 10-day course of antibiotics is used; short course (1- to 3-day) regimens should be avoided. Pyelonephritis should be aggressively managed with hospitalization, rehydration, and intravenous antibiotic therapy based on in vitro sensitivities.

Table 372-2 lists some common antibiotics and special considerations for their use during pregnancy.