Obstetric Topic 36. Infectious diseases in pregnancy. Bacterial and parasite infections

I. Bacterial Infections

Syphilis

• Pathogen: Treponema pallidum; TORCH "other"/syphilis group.
• Fetal effects: miscarriage/stillbirth, preterm birth, early congenital syphilis and late congenital syphilis.
• Early congenital syphilis: jaundice, hepatosplenomegaly, maculopapular rash, snuffles.
• Late congenital syphilis: Hutchinson triad (interstitial keratitis, deafness, Hutchinson teeth), saddle nose.
• Diagnosis: RPR/VDRL screening + treponemal confirmation such as TPHA/TPPA.
• Treatment: benzathine penicillin G IM; penicillin is required in pregnancy.
• Jarisch-Herxheimer reaction: fever, headache, nausea, hypotension/tachycardia; in pregnancy may cause contractions/FHR changes.
• Mechanism: inflammatory response to dying spirochetes, not LPS release.

Gonorrhea

• Pathogen: Neisseria gonorrhoeae, gram-negative diplococcus.
• Maternal effects: cervicitis with thick purulent discharge; may be asymptomatic.
• Neonatal effects: ophthalmia neonatorum with purulent conjunctivitis, corneal damage/blindness.
• Diagnosis: NAAT; culture can show gram-negative diplococci and helps resistance testing.
• Treatment in pregnancy: ceftriaxone IM/IV; treat chlamydia if not excluded.
• Newborn prevention: erythromycin eye ointment; established neonatal disease needs systemic antibiotics.

Chlamydia

• Pathogen: Chlamydia trachomatis.
• Maternal effects: often asymptomatic; cervicitis/discharge may occur.
• Neonatal effects: conjunctivitis and afebrile pneumonia.
• Diagnosis: NAAT.
• Treatment in pregnancy: azithromycin PO; treat partner and confirm cure according to local protocol.
• Newborn eye prophylaxis does not reliably prevent chlamydial conjunctivitis; maternal treatment is key.

Listeriosis

• Pathogen: Listeria monocytogenes, food-borne gram-positive rod.
• Sources: unpasteurized dairy/soft cheese, deli meats, smoked seafood, undercooked meat, contaminated produce.
• Maternal effects: flu-like febrile illness or gastroenteritis; severe disease may cause sepsis/meningitis.
• Fetal/neonatal effects: miscarriage, stillbirth, preterm birth, neonatal sepsis, pneumonia and meningitis.
• Diagnosis: blood culture; culture of amniotic fluid/placenta if clinically indicated.
• Treatment: ampicillin; add gentamicin in severe disease according to protocol.
• Prevention: avoid high-risk foods and use food hygiene.

Group B Streptococcus

• Pathogen: Streptococcus agalactiae; asymptomatic vaginal/rectal colonization is common.
• Maternal effects: often asymptomatic; may cause UTI, chorioamnionitis or postpartum endometritis.
• Neonatal effects: sepsis, pneumonia and meningitis.
• Screening: vaginal-rectal culture late in pregnancy, classically around 35-37 weeks; many current protocols use 36-37 weeks.
• Intrapartum prophylaxis: IV penicillin G first-line; ampicillin acceptable.
• Give prophylaxis for positive culture, GBS bacteriuria, previous affected infant, or unknown status with preterm labor, ROM ≥18 h or fever.

II. Parasitic Infection

Toxoplasmosis

• Pathogen: Toxoplasma gondii, obligate intracellular protozoan; TORCH "T".
• Transmission: raw/undercooked meat, contaminated food/soil, cat feces; fetal infection follows primary maternal infection.
• Maternal effects: often asymptomatic; may cause fever, fatigue and lymphadenopathy.
• Fetal risk: transmission risk rises with gestational age, but early infection is more severe.
• Classic congenital triad: chorioretinitis + hydrocephalus + intracranial calcifications.
• Diagnosis:
  1. Maternal serology: IgG/IgM; avidity helps date infection.
  2. Fetal diagnosis: amniocentesis with PCR for T. gondii DNA when indicated.
  3. Ultrasound: hydrocephalus, intracranial calcifications, hepatosplenomegaly, ascites or FGR.
• Treatment:
  • Maternal infection before fetal infection is documented: spiramycin.
  • Confirmed/suspected fetal infection: pyrimethamine + sulfadiazine + folinic acid after 1st trimester in specialist care.
  • Infected newborn: pyrimethamine + sulfadiazine + folinic acid.
• Prevention: avoid raw meat, wash hands/produce, avoid cat litter or use gloves and hygiene.