Obstetric, perinatal and sexually transmitted infections Flashcards
Why does the immune system change during pregnancy?
- Foetus are non-self, if immune system didn’t change then may reject foetus
What are the immune system changes during pregnancy?
- Placenta acts as immunological barrier
- reduce expression of class 1 MHC antigens on placental cells
- placental syncytium blocks transit of immune system
- T cells inhibited, specifically natural killer cells and T helper one cells
What is the function of T helper one cells?
Respond to intracellular pathogens e.g. viruses and bacteria
What are the consequences for the mother of the lowered immune system?
- increased likelihood of severe symptomatic poliovirus or Hep A
- Rheumatoid arthritis often ameliorates (less painful)
- systemic lupus erythematous can flare up
Describe immune system off foetus
- Few foetal IgM and IgA antibodies produced until second half pregnancy
- No foetal CMI (cell mediated immunity)
- Few foetal IgG antibody produced throughout pregnancy
- Maternal IgG does help protect baby
What infections are more severe in pregnancy?
- Malaria (RBCs infected by malaria can accumulate at placenta)
- Influenza
- UTI (get urinary incontinence due to obstruction, often get pyelonephritis)
- Candidiasis
- Listeriosis
- Varicella
What are the methods of mother to baby transmission?
- Intrauterine infection (during pregnancy) through placenta
- Perinatal transmission (during birth, blood and body fluid mixing)
- Post natal through breast milk e.g. HTLV (human T-lymphotropic virus)
What congenital infections can be transferred through intrauterine transmission?
- Rubella
- Parovirus B19
- CMV (cytomegalla virtu)
- syphilis
- Toxoplasma gondii
- Varicella zoster virus
TORCH synonym o=others
What congenital infections can be transferred through perinatal transmission?
- HIV
- HBV
- Group B streptococci
- Listeria monocytogenes
- Chlamydia trachomatis
- Neisseria gonorrhoea
What is the incubation period of rubella?
14-21 days
What are the symptoms of rubella?
- Fever
- Malaise
- irregular maculopapular rash
- Not very serious
When does rubella become a serious problem?
- Maternal infection of rubella
- particularly in first 16 weeks
- causes sensorineural deafness, diabetes mellitus later in life and can cause cataracts, brain and heart problems
What is rubella infection transmitted by the mother called?
Congenital rubella syndrome
What are the symptoms of erythrovirus (pathovirus B19)?
- Febrile Illness in children and maculopapular rash on face (slapped cheek syndrome)
- or can get symptomless infection, commonly in pregnancy
What happens with B19 in pregnancy?
- very dangerous if infected between weeks 10-20 of pregnancy
- get foetal anaemia due to high number of erythrocytes being made at this time which are targeted by virus
- this causes heart failure and then hydrops foetalis (swelling of baby) can be fatal
How do you try to prevent B19 in pregnant women?
- Tell pregnant women to look out for any children with raises and inform doctor if do come in contact
- Ask children who come to practice and have B19 or rubella if they have had contact with any pregnant women
What should be done if a pregnant women has been in contact with someone with a rash?
- take blood sample to check for presence of immunity or current infections of rubella
- If non-immune another blood sample will be taken 4 weeks after contact to check again
- if positive for infection or immunity B19 given intrauterine blood transfusion rubella termination options
Cytomegalovirus diagnostic test?
- Urine PCR for baby as more virus present in urine than blood
- For women can use blood given when initially booked in to check
is Cytomegalovirus rare?
not very rare 1 in 100 babies, wide range of severity
What factors affect the severity of cytomegalovirus in pregnant women?
- Primary infection (first time) far greater risk of severe disease than if infection has just been reactivated
What type of virus if CMV?
Herpes
What is the severest CMV?
- CMV inclusion disease where affects liver, spleen, blood, brain and eyes
- CMV can also be asymptotic or cause unilateral deafness
What are the symptoms of syphilis in pregnant women and babies?
Maternal - miscarriage, premature births, stillbirths or death of newborn
Congenital - Teeth, brain, ears, bones, hepatosplenomegally, jaundice or anaemia
How is syphilis treated?
Give mother high dose penicillin
what pathogen causes toxoplasma gondii and where may the women come into contact with it?
protozoan parasite found in undercooked meat and cat faeces
What problems can occur in the baby if mother affected by toxoplasma gondii?
- encephalitis, learning difficulties, hepatosplenomegaly and cardiac pulmonary disease
- can also be very mild or asymptomatic
What are the adverse outcomes of chicken pox (varicella virus) in pregnant women?
Congenital varicella syndrome - limb deformities and serious brain and eye abnormalities
Maternal - Pneumonitis (especially if primary infection)
What is the test for women who has come into contact with chickenpox?
- Test immunity, lots have no remembered history of immunity but will be immune (no further action taken if immune)
- If non-immune give VZIG (varicella zoster immunoglobulin) via injection
What is the best treatment for any congenital infections?
Prevention - warning the mother of signs of infection in other and not waiting for infection to present in the women
What conditions are tested for in UK antenatal screening?
HBV, HIV, Syphilis and rubella (only in NI)
What conditions are tested for in UK antenatal screening?
HBV, HIV, Syphilis and rubella (rubella only in NI)
What analyte is checked for in HBV (Hep B)?
HBaAg (checking for current infection)
What analyte is checked for in HIV?
HIV Ag/Ab (checking for current infection)
What analyte is checked for in syphilis?
T palidum total Ab (checking for current or past infection)
What analyte is checked for in rubella?
IgG (checking for immunity)
When is a antenatal screening taken?
13 weeks of gestation
What other tests are necessary and what is the treatment for HBV if positive on screen?
- check for DNA markers, if present more likely to transmit to foetus
- treat by giving baby HBV vaccine and specific immunoglobulins (very effective)
What other tests are necessary and what is the treatment for HIV positive screen?
- HIV viral load, if high load then more likely transmission
- More likely to transmit perinatally so at birth
- Treat with antiretroviral drugs and elective Caesarean section to minimise blood sharing and no breast feeding
What other tests are necessary and what is the treatment for syphilis positive screen?
- Confirm positive using other serological tests
- Treat with penicillin and possibly treat baby also
- follow up baby check antibody presence
What other tests are necessary and what is the treatment for rubella positive screen?
treat with MMR vaccination after pregnancy to protect next pregnancy
What infections can occur around the time of birth?
- Chorioamnionitis (infections of uterine membranes)
- Group B streptococci
- bacterial meningitis (can cause sepsis)
- Neonatal varicella (different from congenital mother gets infection around time of delivery so immune system immature and get varicella)
- HSV infections
What can Chorioamnionitis cause?
- Maternal fever
- premature delivery
- still birth
What are the common symptoms of perinatal infection with STIs?
- Neonatal conjunctivitis (caused by gonorrhoea and chlamydia)
- Pneumonia (caused by chlamydia)
What infections can cause sepsis and/or meningitis in neonates?
- Group B streptococcus (part of normal flora of GI and genital tract in women)
- Listeria monocytogenes
- E.coli
- Enterovirus and parechoviruses
Where can listeria monocytogenes be contracted from?
Unpasteurised milk or cheese or vegetables
transmitted transplacentally
What are the effects of listeria monocytogenes infection?
- Maternal flu and in foetal infection get premature delivery, neonatal septicaemia or pneumonia
- can get early onset neonatal meningitis
What is the treatment for listeria monocytogenes?
Amoxicillin and possible in combination with gentamicin
What does puerperal mean?
time period around six weeks after childbirth
- during this period mother reproductive organs are returning to original condition
What is the major cause of maternal death?
puerperal sepsis mainly Group A streptococcus but can be Clostridium perfringens, E.coli or Group B strep
How is puerperal sepsis prevented?
- Ensure mothers maintain very good hygiene (hand hygiene alone v important)
- avoid anyone with a sore throat
How ar puerperal sepsis diagnosed?
High vaginal swab and blood cultures
Symptoms of puerperal sepsis?
These symptoms if between labour and 42 day postpartum:
- Pelvic pain
- Fever
- Abnormal vaginal discharge
- Delay in rat oef reduction fo size of uterus
What is the first step in any microbiology investigation?
- Take sample of inflamed organ
- Take good culture
How are viral infections checked for in a bay?
- blood sample take clotted blood and EDTA sample
- clotted blood for antibody tests
- EDTA for PCR
- Urine sample to check for CMV
Give example of cultures taken for bacterial infections?
- Throat swab
- HVS
- Blood culture
- CSF
