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GERR > Lecture 51: Obstetric and Perinatal Infections > Flashcards

Lecture 51: Obstetric and Perinatal Infections Flashcards

1
Q

what acts as an immunological barrier in pregnancy

A

placenta

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2
Q

how does placenta act as an immunological barrier

A

allows the mixing of fetal and maternal blood w/o outright immune/inflammatory response to fetus from mother

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3
Q

how does placenta act as an immunological barrier

A
  • reduced expression of class 1 MHC antigens on placental cells
  • syncytium blocks transit of immune cells
  • inhibition of T cells
  • allows the mixing of fetal and maternal blood w/o outright immune/inflammatory response to fetus from mother
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4
Q

what is the placental syncytium

A

outer layer of the placenta in contact w/ maternal blood

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5
Q

describe the adjustment in maternal immune system during pregnancy

A
  • down regulation in TH1 and natural killer (NK) cells
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6
Q

what are TH1 cells

A

CD4 effector T cells involved w/ response to intracellular pathogens e.g. viruses and some bacteria

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7
Q

what are NK cells

A
  • natural killer cells

- innate immune response to virally infected cells acting by secreting interferons and tumour necrosis factor alpha

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8
Q

outline some of the consequences of adjustment in maternal immune system during pregnancy

A
  • consequence for disease
  • increased likelihood of severe symptomatic poliovirus or severe Hep A
  • rheumatoid arthritis often ameliorates
  • systemic lupus erythematosus can flare up
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9
Q

what would happen ig maternal immune system were fully functional

A

allograft rejection i.e. rejection of fetus

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10
Q

describe the fatal immune system in utero

A
  • fetal IgM and IgA Ab not prod in significant amounts until second 1/2 of pregnancy
  • fetal IgG Ab synthesis lacking
  • Fetal CMI absent
  • baby not considered to have significant cell mediated immunity
  • baby can me exposed to maternal IgG which can add a certain amount of protection to baby
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11
Q

what would happen if fetal immune system were fully functional

A

allograft vs host rejection

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12
Q

list some infections that are moire severe in pregnancy and why are they more severe

A
  • malaria
  • flu
  • UTI (esp asc. UTI)
  • candidiasis
  • listeriosis
  • varicella

they affect both mother and fetus

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13
Q

outline how malaria can be so severe in pregnancy

A
  • plasmodium infected erythrocytes accumulate in placenta
  • non immune/partially immune women can have severe infections
  • functioning of placenta is impaired
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14
Q

give categories of mother to baby transmission

A
  • intrauterine (transplacental) infection
  • -> during pregnancy
  • perinatal transmission
  • -> during birth
  • post natal transmission e.g. HTLV (human T-lymphotropic virus) from breastmilk
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15
Q

give some examples of congenital infections that can occur via intrauterine transmission

A
  • rubella
  • parvovirus B19
  • CMV
  • syphilis (treponema palidum)
  • toxoplasma gondii
  • varicella zoster virus

think TORCH

T - toxoplasma gondii 
O - others e.g. parvovirus B19, syphillis varicella zoster 
R - rubella 
C - CMV 
H - herpes
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16
Q

give some examples of congenital infections that can occur via perinatal transmission

A
  • HIV
  • HBV
  • group B strep
  • listeria monocytogens
  • chlamydia trachomatis
  • neisseria gonorrhoeae

(some bacteria can colonise in vaginal fluid and then infect baby during passage through birth canal)

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17
Q

describe rubella infection

A
  • incubation period 14-21 days
  • mild disease; fever, malaise
  • irr. maculopapular rash (lasts 3 days)
  • lymph nodes behind ear
  • arthralgia
  • infection is commonly subclinical (in adults and children)
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18
Q

describe how rubella is vaccinated against

A
  • live attenuated vaccine

- part of MMR vaccine

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19
Q

describe congenital rubella syndrome

A
  • maternal infection <16 weeks gestation (1st trimester)
  • ~80% suffer from sensorineural deafness
  • ~25% develop insulin-dependent diabetes mellitus later in life
  • can develop cataracts, brain and heart problems
  • infant sheds virus into throat and urine for many months and is very infectious
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20
Q

how is rubella virus detected in infants

A

PCR from various specimen sites incl. nasopharynx

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21
Q

describe erythrovirus/parvovirus B19 infection

A
  • febrile illness in children and maculopapular rash on face
  • -> ‘slapped cheek syndrome’
  • -> aka ‘erythema infectiosum’ or ‘5th disease’
  • symptomless infection common in pregnancy
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22
Q

describe B19 infection in pregnancy

A
  • danger is maternal infection weeks 10-20
  • fetal anaemia
  • HF –> hydrops foetalis
  • -> swollen macerated pale fetus - fatal outcome
  • -> cause of “non-immune hydrops” among other things
  • risk about 10% if infection @10-20 weeks
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23
Q

outline the concern, investigations done, and action taken if a pregnant women comes in contact w/ a rash

A
  • focus is on B19 and rubella
  • blood sample taken from mother
  • check IgG and IgM to both viruses
  • -> looking for immunity AND current infection
  • -> if non immune repeat 4 weeks after contact
  • B19 can be treated w/ intrauterine blood transfusion
  • rubella; termination options –> further tests can help define risk
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24
Q

describe congenital CMV

A
  • 1/100 babies born congenitally infected w/ CMV
  • urine CMV PCR +ve at birth
  • majority fine
  • can have congenital CMV syndrome which has a wide spectrum of severity
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25
Q

what is the key test for congenital CMV

A

urine PCR

26
Q

describe maternal CMV infection

A

primary acquired infection:
- higher risk of severe neonatal disease

reactivation infection:
- lower risk of neonatal disease

27
Q

what virus family is CMV part of

A

herpes family

28
Q

describe the spectrum of severity for CMV

A

severe:
- CMV inclusion disease
- -> can affect liver, spleen, blood, brain, eyes

mild:
- asymptomatic
- unilateral sensineural deafness

29
Q

describe the diagnosis of congenital CMV

A

maternal diagnosis:

  • serology
  • seroconversion
  • using booking blood (blood taken when women books into maternity services at start of pregnancy) as baseline to check for immunity

baby diagnosis:
- PCR urine first week of life

30
Q

describe inclusion disease w/ CMV

A

widespread calcification of tissues

31
Q

describe the affect of syphilis infection during pregnancy

A

maternal infection:

  • miscarriages, premature births, stillbirths, death of newborn
  • congenital syndrome
  • -> affects teeth, brain, ears, bones
  • -> hepatosplenomegaly, jaundice, anaemia
32
Q

what is the treatment for maternal syphilis infection during pregnancy

A

high doses of penicillin

33
Q

what is toxoplasma gondii and how can it infect people

A
  • protozoan parasite

- from undercooked meat and cat faeces

34
Q

describe maternal infection of toxoplasma gondii in pregnancy and its effect

A
  • risky to fetus in all 3 trimesters
  • multiple problems in baby
  • -> spectrum; asymptomatic to severe
  • -> treated w/ drugs
35
Q

what does varicella zoster virus cause

A

chickenpox

36
Q

describe the effect of varicella infection during pregnancy to mother and baby

A
  • congenital varicella syndrome (<20 weeks gestation) limb deformities, serious brain fan eye abnormalities
  • can also cause serious infection in pregnant women
  • -> maternal pneumonitis
37
Q

what is done if a pregnant woman is exposed to chickenpox

A
  • test for immunity (VZV IgG)
  • -> 90%+ are immune
  • -> lots of people have no memory of chickenpox
  • if non immune (VZV IgG -ve)
  • -> offer VZIG (varicella zoster immunoglobulin)
  • -> human antibody product
  • -> IM injection
38
Q

outline UK antenatal screening

A

in NI test for:

  • HBV –> HBsAg (assess current infection)
  • HIV –> HIV Ag/Ab (assess current infection)
  • syphilis –> T palidum total Ab (specific test) (assess infection past or present)
  • Rubella –> IgG (assess immunity)
  • single blood sample, booking blood, 13 weeks gestation
39
Q

what is initially done if pregnant woman is HBsAg +ve and why

A
  • do specific markers and HBV DNA
  • -> E antigen +ve more likely to transmit (95% transmit if no intervention)
  • -> high DNA more likely to transmit
40
Q

what is the intervention if pregnant woman is HBsAg +ve

A
  • HBV vaccine for baby
  • +/- specific immunoglobulin
  • -> ~100% effective in preventing MTB transmission
  • -> need to follow up baby at 1yo
41
Q

what is initially done if pregnant woman is HIV +ve

A

do HIV viral load

42
Q

what is the intervention if pregnant woman is HIV +ve

A
  • antiretroviral drugs for mother and baby
  • elective Caesarean section (unless VL undetectable)
  • no breast feeding
  • all to minimise blood/body fluid sharing between mother and baby
  • no intervention; MTB transmission = 25%
  • intervention; MTB transmission = <1%
  • need to follow up baby regularly with PCR and antibody –> all clear @ 18 months
43
Q

what is initially done if pregnant woman is syphilis +ve

A

confirmatory serology

44
Q

what is the intervention if pregnant woman is syphilis +ve

A
  • treat mother w/ penicillin
  • possibly treat baby too
  • follow up baby
  • -> antibody - look for falling levels and eventually disappearance
45
Q

what is done if pregnant woman is rubella non immune

A

offer MMR vaccination AFTER pregnancy

–> to protect next pregnancy

46
Q

outline some infections that can occur at the time of birth

A
  • chorioamnionitis; maternal fever, premature delivery and still birth
  • -> bacteria involved incl. group B haemolytic strep among others
  • bacterial meningitis is frequently fatal unless treated
  • neonatal varicella - maternal chickenpox (7days before/after delivery) - rare
  • HSV infection (relatively rare in UK)
47
Q

what is chorioamnionitis

A

infection of uterine membranes assc. w/ pregnancy

48
Q

outline perinatal infection w/ STIs

A
  • neonatal conjunctivitis (caused by neisseria gonorrhoeae/chlamydia trachomatis)
  • neonatal conjunctivitis = ophthalmia neonatorum
  • C trachomatis can lead to pneumonia ~2 weeks of age
49
Q

give examples of neonatal infections that can cause sepsis and/or meningitis

A
  • group B strep
  • listeria monocytogenes
  • E coli
  • enteroviruses and parechoviruses
50
Q

describe the cause and effects of congenital and neonatal listeriosis

A
  • listeria monocytogenes is gram +ve rod; motile and beta-haemolytic
  • can live at fridge temp
  • maternal flu and bacteraemia –> fetal infection, abortion, premature delivery, neonatal septicaemia, pneumonia w/ accesses or granulomas
  • early onset neonatal meningitis
  • grown from blood cultures, CSF or newborn skin lesions
51
Q

what is the treatment of congenital and neonatal listeriosis

A

amoxicillin

- may need to be combined w/ gentamicin to achieve bactericidal effect

52
Q

describe maternal listeria infection

A
  • many pregnant women can carry listeria asymptomatically in GIT or vagina
53
Q

how can fetal infection of listeria occur from mother

A

transplacental transmission

54
Q

what effect can group B strep have on neonate

A

septicaemia or meningitis

55
Q

describe group B strep presence in women

A

part of normal flora of gut and genital tract and is found in 20-40% women

56
Q

give an example of post natal maternal infection

A

puerperal sepsis

57
Q

what is puerperal sepsis

A

sepsis of uterus and genital tract post partum

puerperal = period of 6 weeks after childbirth; mother’s reproductive organs return to original condition

58
Q

what organisms can cause puerperal sepsis

A
  • strep pyogenes (group A strep)
  • clostridium perfringens
  • Ecoli
  • group B strep
59
Q

who do mothers need to be careful being in contact with after birth to avoid getting group A strep infection

A

people w/ sore throats

60
Q

how can puerperal sepsis be diagnosed

A

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 = >38.5C
  • abnormal vaginal discharge e.g. pus
  • abnormal smell of discharge
  • delay in the rate of reduction of uterus size (<2cm/day during first 8 days)
61
Q

what is the general approach to microbiology investigation

A
  • if inflamed organ site identified, take samples from that site
  • if suspect severe infection/sepsis, take a blood culture (regardless of px temperature)
62
Q

how to check for viral infection in baby

A
  • 4mls clotted blood (serological) or EDTA blood (PCR or nucleic acid amplification)
  • urine (CMV PCR)

GERR (46 decks)

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