Chorioamnionitis, neonatal infection, and omphalitis

Chorioamnionitis is defined as an intrauterine infection of the fetal membranes and amniotic fluid caused by bacteria ascending from the vagina. The most common pathogens are Ureaplasma and Mycoplasma species. Infected women typically present with fever, purulent vaginal discharge, and malodorous amniotic fluid. The combination of maternal (> 120/min) and fetal tachycardia (> 160/min) is highly indicative of intrauterine infection, and the condition should be managed promptly with antibiotics, supportive care, and possibly early delivery.

Chorioamnionitis, as well as colonization of the maternal genital tract with group B Streptococcus, may also be the cause of dangerous infections in the newborn. These include pneumonia, meningitis, and sepsis, and may be difficult to differentiate because symptoms in neonates are often nonspecific. Common findings include irritability, lethargy, temperature changes, dyspnea, and signs of cardiocirculatory distress (e.g., hypotension). If neonatal infection is suspected, diagnostic procedures should be initiated immediately to identify the pathogen and source of infection (e.g., blood and urine cultures). Management consists mainly of swift initiation of broad-spectrum empiric antibiotic therapy. Without proper treatment, systemic neonatal infections are associated with a high risk of complications and increased mortality rates.

Newborns are also commonly affected by localized infections such as omphalitis, an infection of the umbilical stump. The condition is most often caused by Staphylococcus aureus and group A Streptococcus and occurs 3–9 days after delivery. Clinical features include localized inflammation, swelling, and purulent discharge, which may progress to complications like sepsis and necrotizing fasciitis if not treated adequately with antibiotics (e.g., ampicillin, gentamicin).

Etiology

• Infection of the amniotic fluid, fetal membranes, and placenta
• Most commonly due to ascending cervicovaginal bacteria
• Common bacteria: Ureaplasma urealyticum; (up to 50% of cases), Mycoplasma hominis; (up to 30% of cases), Gardnerella vaginalis, bacteroides; , group B Streptococcus; , E. coli
• Risk factors
  • Prolonged labor or premature rupture of membranes (PROM)
  • Pathological bacterial colonization of vaginal tract (e.g., STDs, frequent UTIs)
  • Iatrogenic: multiple digital vaginal exams, invasive procedures (e.g., amniocentesis)

Clinical features

• Maternal
  • Fever (> 38 °C or > 100°F)
  • Tachycardia > 120/min
  • Uterine tenderness, pelvic pain
  • Malodorous and purulent amniotic fluid, vaginal discharge
  • Premature contractions, PROM
• Fetal tachycardia > 160/min in cardiotocography

Diagnosis

Chorioamnionitis is a clinical diagnosis (fever plus ≥ 1 additional symptom). Tests support or confirm diagnosis if the clinical presentation is ambiguous (e.g., in subclinical chorioamnionitis).

• Maternal blood tests
  • Leukocytosis > 15,000 cells/μL (∼ 70–90% of cases)
  • ↑ CRP
• Bacterial cultures
  • Urogenital secretions
  • Amniotic fluid (most reliable, but rarely conducted)
• Group B Streptococcus screening: cervicovaginal and rectal swabs

Management

• Maternal antibiotic therapy
  • Vaginal delivery: IV ampicillin plus gentamicin (broad coverage) ^[1]
  • Cesarean delivery: IV ampicillin and gentamicin, plus clindamycin (anaerobe coverage to minimize postcesarean complications, e.g., endometritis)
• Delivery
  • Swift delivery is generally indicated to minimize both maternal and fetal complications.
  • Cesarean delivery is not generally indicated, but is often necessary because of obstetrical complications (e.g., insufficient contractions).
• For treatment of newborns, see “Neonatal infection” below.

Complications

• Maternal
  • Uterine atony, postpartum hemorrhage, endometritis
  • Septic shock, DIC, venous thrombosis, pulmonary embolism, death
• Fetal/neonatal
  • Fetal death, premature birth
  • Asphyxia, intraventricular hemorrhage, cerebral palsy
  • Neonatal infection (see below)

References:^[1][2][3][4]

Etiology

• Early-onset infection/sepsis
  • ≤ 6 days after delivery ^[5]
  • Common causes: chorioamnionitis, bacterial colonization of the maternal genital tract (pathogen transfer to the infant)
  • Common pathogens: group B Streptococcus (GBS, Streptococcus agalactiae); and E. coli; ; less common are Listeria monocytogenes (see congenital listeriosis), Staphylococcus aureus, Enterococcus, and Haemophilus influenzae.
• Late-onset infection/sepsis
  • 7–89 days after delivery ^[5]
  • Common causes: nosocomial infection
  • Common pathogens: group B Streptococcus; (GBS, Streptococcus agalactiae) and E. coli; less common are coagulase-negative Staphylococcus, Staphylococcus aureus, Klebsiella, Pseudomonas
• Risk factors
  • Maternal
    • Fever
    • PROM, premature labor
    • Infections (e.g., UTI)
  • Fetal
    • Premature birth, low birth weight, low Apgar score
    • Difficult delivery
    • Asphyxia
    • Intravascular catheter or nasal cannula (in late-onset sepsis)

Streptococcus agalactiae and Escherichia coli are the most common causes of both early- and late-onset neonatal sepsis!

Symptoms

General presentation

• Nonspecific
• Irritability, lethargy, poor feeding
• Temperature changes (fever and hypothermia both possible)
• Cardiocirculatory: tachycardia, hypotension, poor perfusion, and delayed capillary refill > 3 sec
• Respiratory: tachypnea, dyspnea; (e.g., expiratory grunting), apnea (more common in preterm infants)
• Skin tone: jaundiced and/or bluish-gray (indicates poor perfusion)

Specific symptoms

• Neonatal meningitis
  • Often no signs of meningism
  • Early phase: general symptoms (see above), vomiting
  • Late phase: bulging fontanelles, shrill crying, seizures, stupor
• Neonatal pneumonia
  • Tachypnea with intercostal/sternal retractions and nasal flaring
  • Reduced oxygen saturation with cyanosis

Diagnosis

• Blood cultures or urine culture for suspected UTI
  • In GBS sepsis: blood agar plate reveals β-hemolytic, gram-positive cocci that enlarge the area of hemolysis formed by S. aureus
• Blood tests
  • Leukocytopenia or leukocytosis, thrombocytopenia
  • ↑ CRP
• Lumbar puncture: test cerebrospinal fluid for possible meningitis
• Chest x-ray: : may reveal clear signs of pneumonia (e.g., segmental infiltrates) but more often nonspecific with diffuse opacities

Management

• Supportive care (cardiopulmonary monitoring and support)
• Broad-spectrum antibiotics: IV ampicillin and gentamicin
  • Indications: clinical suspicion, confirmed or suspected maternal infection (e.g., chorioamnionitis)
• Adapt therapy according to antibiogram results

Prevention

Prophylaxis for neonatal GBS infection (see “Prenatal care”)

Prognosis

• May cause septic shock within hours if treatment is inadequate (mortality rate up to 50%)
• The longer symptoms are present, the higher the risk of developing meningitis.

References:^{[6][7][8][9][10][11][12]}

Etiology

• Bacterial infection of the umbilical stump occurring 3–9 days after delivery
• Pathogens: Staphylococcus aureus, group A Streptococcus, E. coli, Klebsiella pneumoniae
  • Clostridium tetani: common cause of omphalitis and neonatal tetanus in developing countries
• Risk factors: low birth weight, prolonged labor, maternal infection

Symptoms

• Periumbilical redness, tenderness, swelling, and hardening
• Purulent discharge
• Signs of systemic infection (see “Neonatal infection” above)

Diagnosis

• Generally a clinical diagnosis, although cultures should be conducted
• Bacterial cultures: pathogen identification and antibiogram (sample of discharge)
• In systemic infection: blood and cerebrospinal fluid cultures (detection of sepsis and meningitis)

Management

• Broad-spectrum IV antibiotics: antistaphylococcal penicillin (e.g., oxacillin) PLUS aminoglycoside (e.g., gentamicin)
• Surgery: complete debridement if complications arise

Complications

• Sepsis
• Necrotizing fasciitis and myonecrosis (infectious muscle involvement): rare; associated with high mortality rates

Prevention

• Keep the navel dry (frequent diaper change)
• Observe general hygiene measures

References:^[13][14][15]