Obstetric and Neonatal Infections

Question 1

Changes in immune system during pregnancy

Answer 1

• 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

Question 2

Common infections during pregnancy

Answer 2

• 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)

Question 3

Infections that are more severe during pregnancy

Answer 3

• 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

Question 4

Pyelonephritis during pregnancy

Answer 4

• 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

Question 5

Pathogens assoc. UTIs

Answer 5

• E. coli (~60% of cases)
• Group B streptococci
• Proteus mirabilis
• Enterococci
• Klebsiella pneumoniae

Question 6

Chorioamnionitis

Answer 6

• 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

Question 7

Chorioamnionitis Risk Factors

Answer 7

• BV, STI or GBS colonization
• Prolonged rupture of the membranes
• Prolonged labor
• Freq. vaginal exams during labor
• Internal fetal monitoring

Question 8

Chorioamnionitis Signs

Answer 8

• Maternal fever

*>100.4

• Maternal or fetal tachycardia
• Uterine tenderness
• Leukocytosis
• Foul smelling amniotic fluid (uncommon)

Question 9

Chorioamnionitis Diagnosis

Answer 9

• Definitive diagnosis = culture of amniotic fluid
• If bacteria remain limited to the amniotic fluid, maternal illness is unlikely

Question 10

Chorioamnionitis Treatment

Answer 10

• Induction of labor
• Broad-spectrum antibiotics during labor

*cover gram+, gram -, aerobes and anaerobes

• Antibiotics not needed after delivery unless mother remains febrile

Question 11

Chorioamnionitis possible consequences

Answer 11

• 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)

Question 12

Puerperal fever

Answer 12

• 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

Question 13

Postpartum Endomyometritis Risk Factors

Answer 13

• 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

Question 14

Postpartum Endomyometritis Symptoms

Answer 14

• Fever, uterine tenderness, tachycardia, purulent vaginal discharge

Question 15

Postpartum Endomyometritis Treatment

Answer 15

• Broad-spectrum antibiotics

Question 16

Postpartum Endomyometritis possible consequences

Answer 16

• Can develop into septic shock, pelvic thrombophlebitis, pelvic abscess

*thrombi form in pelvic veins as a result of pregnancy-induced hypercoagulability

Question 17

Neonatal infections acquired during passage down an infected birth canal

Answer 17

• 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

Question 18

Neonatal Sepsis

Answer 18

• 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

Question 19

Clinical manifestation of neonatal sepsis

Answer 19

• 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

Question 20

Early onset sepsis

Answer 20

• 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

Question 21

Late onset sepsis

Answer 21

• 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

Question 22

Group B streptococcus

Answer 22

• 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

Question 23

Maternal GBS infections

Answer 23

• UTI
• Chorioamnionitis
• Septicemia
• Endomyometritis
• Postoperative wound infection after cesarean section

Question 24

GBS transmission infection to newborns risk factors

Answer 24

• 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

Question 25

Early onset GBS infection

Answer 25

- 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

Question 26

Late onset GBS infection

Answer 26

- 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

Question 27

GBS screening/prophylaxis

Answer 27

- 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

Question 28

Neonatal Herpes

Answer 28

- Primary genital herpes in mother---\>inc. risk of sponataneous abortion, intrauterine growth retardation and preterm birth - Reactivation of infection- complications rare

Question 29

Neonatal Herpes Transmission

Answer 29

- 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

Question 30

Neonatal Herpes Clinical Manifestations

Answer 30

- Skin, eye and/or mouth infection - Disseminated disease involving numerous organs \*pneumonitis, hepatitis, cardiovascular involvement, meningoencephalitis - CNS disease (encephalitis)

Question 31

Neonatal Herpes Treatment

Answer 31

- 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)

Question 32

Varicella Zoster virus infection prior to delivery

Answer 32

- 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)

Question 33

Varicella Zoster virus consequences for newborn

Answer 33

- 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

Question 34

Listeria monocytogenes infection during pregnancy

Answer 34

- Maternal infection- usually mild influenza-like illness - Transmission to baby \*across placenta \*postnatal - Neonatal infection \*meningitis

Question 35

Hepatitis B virus during pregnancy

Answer 35

- 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

Question 36

Transmission of HBV statistics

Answer 36

- 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

Question 37

Hepatitis C virus during pregnancy

Answer 37

- 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