Obstetric and Neonatal Infections Flashcards
Changes in immune system during pregnancy
- General immunosuppression does not occur w/ pregnancy
- Shift from TH1 to TH2 immunity
*TH2 stimulates B cells; inc. antibody production; dec. cytotoxic T cell response
- Innate immunity maintained
*phagocytic activity; neutrophils, moncytes, dendritic cells
- Inflammatory cytokines dec.; phagocytic cell recruitment and activity inc.
- Effect of hormones
*low estradiol promotes CD4+ TH1 response and CMI
*high estradiol promotes CD4+ TH2 response and humoral immunity
*progesterone suppresses maternal immune response and alters TH1/TH2 ratio
Common infections during pregnancy
- UTI
*cystitis; pyelonephritis more common
- Salmonella infections
*incidence higher in pregnancy; no adverse effect on fetus
- Listeriosis
*incidence higher in pregnancy; mild or asymptomatic in mother; severe consequences in infant
- Candidiasis
*hormones favor growth of yeast
- Malaria (plasmodium falciparum)
*increased susceptibility and severity (especially w/ 1st pregnancy)
Infections that are more severe during pregnancy
- Influenza
*higher mortality during pandemics
- Coccidioidomycosis
*some studies suggest inc. severity and dissemination during pregnancy; (not all studies confirm)
- Varicella (chicken pox)
*inc. resk of preterm labor, pneumonia and encephalitis (not all studies confirm)
- Herpes simplex virus
*inc. risk of dissemination and hepatitis w/ primary infection; more frequent genital herpes recurrences
- Malaria
*P. falciparum- tropism for the placenta
- Hepatitis E virus
*more severe illness during pregnancy
- Increased severity tends to be in 3rd trimester
Pyelonephritis during pregnancy
- 2-4% of pregnancies most often during 2nd trimester
- Symptoms of cystitis plus flank pain, fever, rigors
- Can cause septic shock and ARDS in pregnancy
- May require hospitalization, IV antibiotics, monitoring for premature labor
- Recurrent infections occur in 10-25% of pts
Pathogens assoc. UTIs
- E. coli (~60% of cases)
- Group B streptococci
- Proteus mirabilis
- Enterococci
- Klebsiella pneumoniae
Chorioamnionitis
- Infection of the placenta, amniotic fluid and fetal membranes
- 1-2% of term deliveries; 5-10% of preterm deliveries
*high assoc. w/ preterm birth and preterm premature rupture of membranes
*the long the time after rupture of membrane, the higher the likelihood of colonization of the amniotic fluid
- 96% of cases are ascending polymicrobial infection caused by normal vaginal flora
*most common pathogens: ureaplasma urealyticum, mycoplasma hominis, prevotella bivia, garnerella vaginalis, group b strept, E. coli
- 4% of cases- spread from mother via blood
*listeria monocytogenes, haemophilus influenzae, streptococcus pneumoniae, salmonella typhi and group A streptococci
Chorioamnionitis Risk Factors
- BV, STI or GBS colonization
- Prolonged rupture of the membranes
- Prolonged labor
- Freq. vaginal exams during labor
- Internal fetal monitoring
Chorioamnionitis Signs
- Maternal fever
*>100.4
- Maternal or fetal tachycardia
- Uterine tenderness
- Leukocytosis
- Foul smelling amniotic fluid (uncommon)
Chorioamnionitis Diagnosis
- Definitive diagnosis = culture of amniotic fluid
- If bacteria remain limited to the amniotic fluid, maternal illness is unlikely
Chorioamnionitis Treatment
- Induction of labor
- Broad-spectrum antibiotics during labor
*cover gram+, gram -, aerobes and anaerobes
- Antibiotics not needed after delivery unless mother remains febrile
Chorioamnionitis possible consequences
- Puerperal (intrapartum) fever
- Severe morbidity/mortality in mother assoc. w/:
*septic shock
*clostridium perfringens infection (myonecrosis or gas gangrene)
*postpartum endomyometritis w/ septic thrombophlebitis
*necrotizing fasciitis- necrosis of fascia and subcutaneous tissue (group A strep or polymicrobial)
Puerperal fever
- Fever that lasts >24hrs within the 1st 10 days post delivery
- Most common cause—> postpartum infection of the uterus (at placental site)
*endomyometritis
- Contaminated amniotic fluid sets mother up for infection
*post c-section wound infection
*could involve infection of lacerations in cervix, vagina or perineum (wound infection)
- Dissemination via blood or lymphatics:
*sepsis; peritonitis
Postpartum Endomyometritis Risk Factors
- Same as chorioamnionitis
*prolonged labor and premature rupture of membranes
*BV, freq. vaginal exams, fetal monitoring
- Cesarean, forceps or vacuum delivery
- Manual removal of the placenta
- Retained placental fragments of fetal membranes
*provide favorable environment for bacteria growth
- Usually mixed infections
*anaerobes (bacteroides, prevotella, peptostreptococci)
*E. coli and GBS- major pathogens
Postpartum Endomyometritis Symptoms
- Fever, uterine tenderness, tachycardia, purulent vaginal discharge
Postpartum Endomyometritis Treatment
- Broad-spectrum antibiotics
Postpartum Endomyometritis possible consequences
- Can develop into septic shock, pelvic thrombophlebitis, pelvic abscess
*thrombi form in pelvic veins as a result of pregnancy-induced hypercoagulability
Neonatal infections acquired during passage down an infected birth canal
- GBS, E.coli, Group A strep
*manifest w/ sepsis, pneumonia, meningitis
- Enterococcus
*UTI, sepsis
- Listeria monocytogenes
*sepsis, meningitis, diarrhea
- NG and CT
*neonatal conjunctivitis (opthalmia neonatorum)
- Herpes simplex virus
*neonatal herpes
- Genital papillomavirus
*laryngeal warts in young children
- Candida albicans
*oral thrush
Neonatal Sepsis
- Systemic illness w/ bacteremia that occurs in the 1st month of life
*often includes pneumonia and meningitis
*incidence = 1-5/1000 live births (more common in very low birth weight babies)
- Mortality = 13-25%
*higher in premature infants
Clinical manifestation of neonatal sepsis
- Can be nonspecific, subtle
- Temp. irregularity
*hypothermia more common than fever w/ bacterial sepsis
*fever more common w/ viral agents (HSV)
- Lethargy, irritability
- Cyanosis, mottling, pallor, petechiae, rashes, jaundice
- Tachypnea, respiratory distress, apnea
- Vomiting, diarrhea, abdominal distention
- Hypoglycemia, hyperglycemia, metabolic acidosis
Early onset sepsis
- Occurs in 1st 5-7days of life
- Multisystem illness; prominent respiratory symptoms
*chorioamnionitis can lead to aspiration of infected amniotic fluid, which may contribute to respiratory involvement
- Sudden onset that can progress rapidly to septic shock and death
- Most common organism- group B streptococcus
- 2nd most common- gram (-) enterics, especially E.coli
- Others- listeria monocytogenes, enterococci, anaerobes
Late onset sepsis
- Occurs >5 days of life
- Nosocomial infection
*transmission from mother, health care worker in nursery
- Bacteremia, sepsis and often meningitis
*less severe systemic and respiratory symptoms
- Major pathogen- coagulase neg. Staphylococcus (S. epidermidis)
- Others: gram (-) rods (pseudomonas, klebsiella, serratia, proteus), s. aureus, GBS, listeria monocytogenes
Group B streptococcus
- Streptococcus agalactiae; Beta-hemolytic
- Normal flora of GI tract and GU tract
*vaginal carriage rates 15-40% (transient colonization ~2/3, chronic 1/3)
- Transmission to neonate during birth
*35-70% transmission rate
*invasive disease uncommon in term infants; morbidity and mortality more common in preterm infants
- Most common cause of neonatal sepsis in the US
*1-2 cases/1000 live births
Maternal GBS infections
- UTI
- Chorioamnionitis
- Septicemia
- Endomyometritis
- Postoperative wound infection after cesarean section
GBS transmission infection to newborns risk factors
- Preterm labor
- Preterm rupture of membranes
- Low birth weight
- Prolonged rupture of membranes (>12hrs before delivery)
- Maternal puerperal fever
- History of previous infant w/ GBS
*history of GBS colonization
Early onset GBS infection
- 1-2% of colonized infants develop early onset GBS infection; 11-50% fatality
*preterm infants at higher risk of sepsis and death than full term infants
- Symptoms within 1st 48hrs after birth
- Respiratory distress and pneumonia
- Septicemia—>shock
- Meningits in 30%
*assoc. w/ GBS serotype III
- ~equal representation of serotypes Ia-c, II and III
Late onset GBS infection
- 0.5-1.8/1000 live births
- Mortality ~10%
- Usually due to nosocomial infection in the nursery
- Occurs after 1st week of life
- Meningitis- 80-90% of cases
*most cases of late onset GBS infection are due to serotype III
*neurological sequelae in 15-30% of meningitis survivors
- Sepsis and pneumonia also possible
GBS screening/prophylaxis
- Screen at 35-37wks gestation for vaginal and rectal colonization
*culture or PCR
- Intrapartum antibiotics given to GBS carriers
*GBS isolated from urine (sign of heavy colonization)
*women w/ previous infant w/ GBS sepsis
*signs of chorioamnionitis
*rupture of membranes for >18hrs w/ unknown GBS infection
- Prophylaxis prevents ~80% of GBS infections
- Incidence of late onset disease is not decreased
Neonatal Herpes
- Primary genital herpes in mother—>inc. risk of sponataneous abortion, intrauterine growth retardation and preterm birth
- Reactivation of infection- complications rare
Neonatal Herpes Transmission
- Transmission
*intrauterine- 5%
*peripartum- 85%
*postnatal- 10%
- Risk of neonatal infection in mom w/ genital herpes actively shedding virus at the time of birth:
*primary infection = 30-45%
*recurrent infection = ~5-8%
- Onset of symptoms typically b/w 4th and 10th day of life
Neonatal Herpes Clinical Manifestations
- Skin, eye and/or mouth infection
- Disseminated disease involving numerous organs
*pneumonitis, hepatitis, cardiovascular involvement, meningoencephalitis
- CNS disease (encephalitis)
Neonatal Herpes Treatment
- Active genital HSV infection at time of birth = cesarean section
- Treatment = IV acyclovir
*disseminated disease can result in infant mortality or sequellae, even w/ treatment (microcephaly, mental retardation, seizures)
Varicella Zoster virus infection prior to delivery
- Maternal infection 5-21 days before delivery
*mild, self-limited infection in newborn
*maternal antibodies provide protection
- Maternal infection 5 days before to 2 days after delivery
*transplacental transmission places newborn at risk for severe morbidity
*no transplacental transfer of maternal antibodies (requires at least 5 days after onset of rash in mother)
*25-30% mortality for newborn
*infant treated w/ varicella zoster immune globulin (VZIG)
Varicella Zoster virus consequences for newborn
- Possible outcomes in newborn following maternal primary infection near time of birth
*typical varicella (chicken pox)
*disseminated infection
*shingles-months or years after birth
- Zoster during pregnancy- not assocl. w/ sequellae in fetus
*protected by maternal antibody
Listeria monocytogenes infection during pregnancy
- Maternal infection- usually mild influenza-like illness
- Transmission to baby
*across placenta
*postnatal
- Neonatal infection
*meningitis
Hepatitis B virus during pregnancy
- Course of acute HBV in mother no changed during pregnancy
- Transmission can be prenatal, during delivery or postpartum
*transmission during delivery is most common
- HBV immune globulin (HBIG) should be given to neonate of infected mother with 12hrs of birth; followed by HBV vaccine
Transmission of HBV statistics
- Risk of transmission = ~90% in mother w/ active infection (HBsAg and HBeAg pos.)
- Risk of transmission = ~10-30% in inactive carrier (HBsAg and anti-HBe pos.)
- Maternal infection in 1st trimester - 10% of neonates are seropositive
- Maternal infection in 3rd trimester - 80-90% of neonates are infected
- HBeAg in neonate - 85-90% likelihood of chronic infection in newborn
Hepatitis C virus during pregnancy
- Mother to baby transmission ~4-6% in HCV RNA+ mother
*co-infection with HIV increases risk of HCV transmission to baby
- Transplacental trasnmission puts neonate at increased risk of acute HCV and probably chronic infection
- No teratogenic syndromes assoc. w/ HCV
