MB14 Obstetric and Perinatal Infections Flashcards Preview

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Flashcards in MB14 Obstetric and Perinatal Infections Deck (35):
1

Learning Outcomes (for general perusal)

Be able to describe

 

•Immune factors which play  a role in susceptibility to infection in pregnancy.

•Targets of the antenatal infectious diseases screening programme.

•Important bacterial and viral causes of congenital and perinatal infection.

•Choosing which specimens to test

•Contact with a rash in pregnancy

- rubella and parvovirus B19 and VZV

2

Why is immune tolerance a vital component of pregnancy?

 

What does the placenta act as?

Fetus and placenta are allografts (NON-SELF)

 

An immunological barrier

3

Placenta

How does it act as an immunological barrer?

  • Reduced expression of class 1 MHC antigens on placental cells
  • Syncytium  blocks transit of immune cells
  • Inhibition of T cells

4

Maternal Immune System During Pregnancy

  1. In which cells are there changes?
  2. What are the consequences of these changes for disease?
  3. What would happen if the maternal immune system was fully functional?

  1. Less Th1 and NK cells
  2. increased likelihood of severe symptomatic poliovirus or hepatitis A virus

    –Rheumatoid arthritis often ameliorates

    –systemic lupus erythematosus can flare up.

  3. 'Graft' rejection

5

Fetal Immune System

  1. When are fetal IgM and IgA antibodies first produced in significant amounts?
  2. Which antibody synthesis is lacking?
  3. What is absent?

  1. The second half of pregnancy
  2. fetal IgG antibody synthesis
  3. Fetal CMI (cell mediated immunity)

6

Name the infections that are more severe in pregancy

Effects on mother and foetus 

Malaria

Inflluenza

UTI

Candidiasis (thrush)

Listeriosis

Varicella (VZosterVirus)

 

7

Mother to Baby Transmission

  1. Define INTERUTERINE infection
  2. Define PERINATAL transmission

  1. During pregnancy 
  2. During birth

8

Congenital infections

  1. Name congential infections acquired by ntrauterine transmission (via placenta)
  2. Name congential infections passed by perinatal transmission

  1. –Rubella

    –Parvovirus B19

    –CMV

    –Syphilis (Treponema palidum)

    –Toxoplasma gondii

    –Varicella zoster virus

  2. –HIV (very occasional intrauterine transmission)

    –HBV

    –Group B streptococci

    Listeria  monocytogenes (can also be intrauterine)

    –Chlamydia trachomatis

    –Neisseria gonorrhoeae

9

What are the categories of motor to baby infection by Transmission, and give examples

Intra-uterine

Rubella, CMV, Toxoplasma

Peri-natal

HIV HSV

Post-Natal

HTLV -  human T-lymphotropic virus (breast milk)

10

Rubella

  1. ​What is the incubation period?
  2. What are the symptoms?
  3. Why is it rare in the UK?

  1. 14-21 days
  2. mild disease - fever, malaise, irregular maculopapular rash which lasts 3 days. Lymph nodes behind the ear, arthralgia. Infection is commonly subclinical. 

  3. Part of MMR vaccination - live attentuated vaccine

11

Congenital Rubella Syndrome

  1. When does this occur?
  2. What do the infected children suffer from?
  3. Why is the child very infectious for several months?

  1. Maternal infection
  2. ~ 80% suffer from sensorineural deafness.

    ~ 25% develop insulin-dependent diabetes mellitus later in life

    Cataracts, brain and heart problems

  3. infant sheds virus into the throat and urine for many months 

12

Erythrovirus // Parvovirus B19

  1.  What are the symptoms?
  2. When is there are particular danger in maternal infection of B19? Why?

  1. Febrile illness in children & maculopapular rash on face, ('slapped cheek syndrome'), AKA 'erythema infectiosum’ or 'fifth disease'. Symptomless infection is common

  2. weeks 10 – 20. Will cause fetal anaemia, heart failure, hydrops foetalis (swollen macerated foetus), fatal. (Risk about 10%) (B19 as a cause of non-immune hydrops)

13

  1. What are the worries when coming into contact with a rash in pregnancy?
  2. What should be done?
  3. How can B19 be treated?
  4. What if rubella is positive?

  1. Focus is on B19 and rubella

  2. Take sample of blood from mother, IgG and IgM to both viruses. Looking for immunity AND current infection

    If non-immune repeat 4 weeks after contact to check if she has B19. (test for immunity, if not immune, follow up and intervene)

  3. Intrauterine blood transfusion

  4. termination options – further tests can help define risk

14

Case

12 weeks gestation: household contact with slapped cheek syndrome

Developed rash but reassured no action necessary

23 weeks gestation: US – showed fetal hydrops.

Parvovirus B19 IgM positive and  PCR positive

2x intrauterine blood transfusion in Glasgow.

25 weeks gestation: showed resolution of ascites but borderline cardiomegaly

35 weeks gestation: emergency CS for premature labour and breech presentation

15

CMV (Cytomegalovirus)

  1. How is it diagnosed?
  2. What are the risks with Maternal infection? How is it diagnosed?
  3. How can a baby be affected in Congential CMV?

 

  1. urine CMV PCR positive at birth

  2. Reactivation and Primary infection (higher risk). –Serology, seroconversion, using booking blood.

  3. 1 in 100 babies born with congential CMV

    1. Spectrum from mild asymptomtic infection to unilateral sensineural deafness, to severe end: CMV INCLUSION DISEASE (liver, spleen, blood, eyes, brain)

16

Syphilis

  1. What consequences can maternal infection have?
  2. What symptoms does the congential syndrome have?
  3. How is the mother treated?

  1. miscarriages, premature births, stillbirths, or death of newborn

  2. Affects teeth, brain, ears, bones, Hepatosplenomegally, jaundice, anaemia

  3. Penicillin

17

Toxoplasma gondii

  1. What is it, where is it from?
  2. When is infection risky to the foetus?
  3. Generally, what does it cause?

  1. Protozoan parasite, undercooked meat and cat faeces
  2. In all three trimesters of gestation
  3. Spectrum of symptoms, from aymptommatic to very severe, can be treated with drugs

18

Varicella – Chickenpox

  1. When does Congenital Varicella Syndrome occur?
  2. What will it cause?
  3. What risks are there to the mother?
  4. What actions should be taken if a pregnant woman has been exposed to chickenpox?
  5. What should be done if the mother isn't immune?

  1. <20 weeks gestation
  2. limb deformities, and serious brain & eye abnormalities

  3. Can cause serious infection: maternal pneumonitis

  4. Test for immunity (VZV IgG). (90%+ are immune) - But lots of people have no remembered history of chickenpox

  5. Offer VZIG (Varicella zoster Immunoglobulin)

    •Human antibody product IM injection

19

UK Antenatal Screening

Consider the following agents

  1. HBV
  2. HIV
  3. Syphilis
  4. Rubella

What are their analyte and what can they assess?

5. How are these assessed?

  1. HBsAg - current infection
  2. HIV Ag/Ab - Current infection
  3. T Pallidum Total Ab (specific test) - infection past or present
  4. IgG - Immunity
  5. Single blood sample (booking blood at 13 weeks gestation)

 

20

What are the 4 components of the UK Antenatal Screening program?

HBV, HIV, Syphilis, Rubella

 

 

21

  1. What does the analyte HBsAG test for?
  2. What DNA markers are likely to be present?
  3. What interventions can be taken if this is a positive test?
  4. How effective are the interventions?

  1. HBV
  2. –E antigen positive more likely to transmit

    –High DNA more likely to transmit

  3. HBV vaccine for baby, +/- Specific Immunoglobulin

    1. (95% of E antigens will transmit mother to baby if no intervention)

  4. ~100% effective in preventing MTB transmission

22

  1. How can HIV be tested?
  2. What are the interventions?
  3. How effective are the interventions?
  4. What follow up will be needed?

  1. Combined antibody and antigen test, HIV viral load can be tested
  2. Antiretroviral drugs for mother and baby

    Elective caesarean section (unless VL undetectable) and No breast feeding

  3. No interventions = 25% MTB transmission, this decreases to less than 1% with interventions

  4. Need to follow up baby regularly with PCR and antibiody – all clear @18months

23

  1. What will positive syphilis serology show?
  2. What are the interventions?

  1. Anti T. pallidum IgG
  2. Treat mother with penicillin (possibly baby too)
    1. Follow up baby - antibody - look for falling levels and eventual disappearance. If congentially infected, then the antibodies will be initially high then fall away

24

What steps need to be taken if the mother is not immune to Rubella? (Rubella IgG <10 iu/ml)

 

Offer MMR vaccination AFTER pregnancy

–I.e. To protect next pregnancy

25

Infections around the time of birth

  1. What can these cause?
  2. What are the bacteria involved?
  3. What is of particular concern?
  4. When can neonatal varicella occur?

  1. Chorioamnionitis, maternal fever, premature delivery and stillbirth. 

  2. group B hemolytic streptococci amongst others

  3. Bacterial meningitis is frequently fatal unless treated. 

  4. maternal chickenpox (7days before/after delivery) Rare

26

  1. What is another name for neonatal conjunctivitis?
  2. What can it be caused by?
  3. What else can C.Trachomatis lead to?

  1. Ophthalmia neonatorum

  2. Neisseria gonorrhoeae / Chlamydia trachomatis 

  3. Can lead to pneumonia

    ~ 2 weeks of age

    Eye / URTI => pneumonia

27

Which neonatal infections present as sepsis and/or meningitis?

 

  • Group B streptococcus.
  • Listeria monocytogenes
  • E Coli,
  • Enteroviruses and parechoviruses

28

Congenital and neonatal listeriosis

  1. What causes it? Describe the microorganism
  2. What is a particular danger?
  3. What are the symptoms?
  4. How can it be tested for?
  5. What is the treatment?

  1. Listeria monocytogenes - Gram-positive rod, which is motile and beta-hemolytic
  2. Listeria can grow at regular refrigeration temperatures (e.g. 3-4°C) –  unpasteurized milk or soft cheeses or contaminated vegetables. 

  3. •Maternal “flu” + bacteremia = fetal infection - abortion, premature delivery, neonatal septicemia or pneumonia with abscesses or granulomas.

    •Early onset neonatal meningitis. 

  4. Grown from  blood cultures, cerebrospinal fluid (CSF) or newborn skin lesions.

  5. ampicillin , which may need to be combined with gentamicin to achieve a bactericidal effect. 

29

  1. Where do many pregnant women carry Listeria asymptomatically?
  2. What can maternal infection with listeria result in?
  3. How can foetal infection occur?

  1. in their GI tract or vagina
  2. chorioamnionitis, premature labor, spontaneous abortion, or stillbirth.
  3. via transplacental transmission

30

Group B Streptococci

  1. Why can this be serious for a neonate?
  2. Where does it normally reside?
  3. Does screening occur?
  4. What can post-natal maternal infection bring about?

  1. Septicaemia / meningitis
  2. A part of normal flora of the gut and genital tract and is found in 20–40% women. 

  3. In US (at 36 weeks), no screening in UK

  4. Puerperal sepsis

    –Sepsis of uterus & genital tract post partum

31

Centre for Maternal and Child Enquiries (CMACE) 2006-8

 

  1. What is the maternal death rate?
  2. What are many infections caused by?
  3. What is there a need for?

  1. Maternal Death Rate  - 4.67 /100000
  2. Many due to Group A Strep (GAS)
  3. Mothers and HCWs need for scrupulous hygiene especially after birth and where new mothers are in contact with people with sore throats.  

32

What is Puerperal Sepsis?

Infection of the genital tract occurring at any time between the rupture of membranes or labour, and the 42nd  day postpartum in which 2 or more of the following are  present:

Pelvic Pain

Fever =>38.5 ° C

•Abnormal vaginal discharge eg pus

•Abnormal smell of discharge

Delay in the rate of reduction of size of uterus (<2cm/day during the first 8  days)

(after birth there should be gradual decline in the size of the uterus, if this isnt occuring, puerperal sepsis may be present)

33

Puerperal Sepsis

  1. What causes it?
  2. How can a diagnosis be made?
  3. What can prevent it?

  1. Streptococcus pyogenes

    Clostridium perfringens

    E coli

    Group b streptococci

  2. High vaginal swab - culture

  3. Hand hygiene massively reduced frequency. (Uterine tissue is susceptible to infection post delivery- Major cause of death 19th century. 10% mortality)

34

How can VIRAL INFECTION be checked for in the baby?

  • 4 mls Clotted Blood
    • e.g. Enterovirus, CMV, Toxoplasma, rubella
  • Urine
    • CMV PCR
  • Faeces
    • Enterovirus PCR

35

How can BACTERIAL INFECTION be checked for the in  the baby?

  • Throat swab
  • HVS
  • Blood Cultures
  • CSF