24 Obstetric and perinatal infections Flashcards
Placenta normally provides effective barrier to most circulating microbes.
Certain infections are more severe in pregnancy, as there is subtle immunosuppression, to prevent rejection of foetus.
Infection in first trimester associated more serious adverse outcome because heart/ brain/ eyes are still developing
What are examples?
Malaria
Viral hepatitis
Influenza
Polio
UTI/ pyelonephritis more common
Listeriosis
Coccidiomycoses
Foetus has very immature immune system. This is to prevent foetal immune response to mother
What are the defects?
IgM/ IgA not produced in significant amount until late in pregnancy
No IgG antibody synthesis - all from mother
Cell mediated response poorly developed, lack of production of cytokines
What are congenital defects if infected foetus?
CMV
Zika
CMV - sensorineural hearing loss, mental retardation, chorioretinitis, optic atrophy, hepatosplenomegaly. Most infections in mother asymptomatic, and most do not cause issue for baby
Zika - microcephaly, facial disproportionality
What are congenital defects if infected foetus?
VZV
HSV
VZV - skin lesions, limb deformities, CNS abnormalities
HSV - disseminated infection - including encephalitis
What are congenital defects if infected foetus?
Listeria
Wide variety of animals carry listeria. Contact with animals/ faeces/ unpasteurised milk/ cheese can spread infection
Listeria - pneumonia, meningitis
Infection also occurs during and immediately after birth
Causes mild influenza like illness in mother
What are congenital defects if infected foetus?
Rubella
Does not direct damage, but interferes with mitosis
LBW
Cataract
mental retardation
IDDM - virus replicates in pancreas
heart defects
How to diagnose congenital rubella?
Maternal IgG/ IgM and RNA PCR
Neonate IgM and RNA PCR in cord blood
Neonate PCR throat swab/ urine
Baby with hearing/ eye defects needs investigation for CMV.
How is it diagnoses?
Maternal IgG/ IgM and DNA PCR
Neonate IgM within 3 weeks of delivery
Neonate DNA PCR in blood/ urine/ saliva
Zika virus is a flavivirus. What are other flaviviruses?
Yellow fever
Dengue
West Nile virus
What is vector for zika?
80% of infections are asymptomatic
Aedes aegypti
What are congenital effects of zika?
Microcephaly
Eye defects
What are congenital defects if infected foetus?
Toxoplasmosis
Between 10% and 80% of adults have evidence of infection at some point with toxoplasmosis. Highest risk of primary infection in mother in pregnancy
Avoid infection by avoiding cysts in cat faeces, or undercooked meat
epilepsy
micocephaly
mental retardation
chorioretinitis
Mother suspected of toxoplasma infection in pregnancy.
What is treatment?
Spiramycin to prevent transmission to foetus
If toxoplasma PCR of amniotic fluid confirms fetal infection, treat mother with sulphadiazine plus pyrimethamine plus folinic acid instead of spiramycin
Chagas disease can be spread verticlaly, and via blood transfusion. Normally spread by reduvii bug.
What symptoms can it cause foetus?
prematurity
LBW
anaemia
hepatosplenomegaly
meningoencephalitis
If untreated can cause cardiac/ gastrointestinal complications in 20-30 years
Infections can also occur during/ after birth for neonate.
Risk increased if PROM. What is definition?
rupture of membranes for >18 hours before labour onset
Which organisms are transmitted during delivery?
GBS - sepsis
E. coli/ klebsiella/ proteus
Staph
Gonococci - opthalmia neonatorum
chlamydia - conjunctivitis, pneumonia
HSV - disseminated
HIV
HSV can be transmitted to baby, as only 80% of mothers with primary infection will develop lesions. Can lead to encephalitis/ pneumonia
Diagnosed by HSV DNA PCR blood/ vesicles
What is treatment for primary HSV infection?
What is treatment for primary HSV infection if presenting in labour?
What is treatment for recurrent HSV infection?
Primary HSV (not in labour)
- If >28 weeks recommend C-section
- If <28 weeks can have normal vaginal delivery
- start mother on aciclovir treatment 400mg TDS 5 days as risk transmitting to baby
Primary HSV presenting at onset labour -
- Recommend C-section all patients
- IV aciclovir 5mg/kg TDS 5 days mother.
- IV aciclovir 20mg/kg TDS for neonate (consider this)
Recurrent is less of an issues, as mother will transfer IgG to baby. Often have normal vaginal delivery -
- <36 weeks - analgesia/ saline wash
- > 36 weeks - aciclovir suppressive dose 400mg TDS until delivery
HCV has little vertical transmission.
On the other hand, HBV has high vertical transmission rate.
How to prevent transmission to baby?
Give baby vaccine and HBIG immediately after birth
Give mother HBIG if highly infectious prior to delivery
Staph aureus can cause neonatal infection. What is the usual clinical picture?
Toxin produced can cause scaled skin syndrome
What are risks to umbilical stump?
Tetanus - resource poor countries use dirty tools to cut
Which antibiotics are absolutely contraindicated in pregnancy?
Tetracyclines - tooth/ bone defects
Quinolones - cartilage damage
Clarithromycin - birth defects. Other macrolides are safe
Aminoglycosides - ototoxicity
Chloramphenicol - gray baby syndrome
Which antibiotics are considered safe in pregnancy?
Penicillin
Carbapenems
Cephalosporins
Macrolides (except clarithromycin)
Metronidazole - except first trimester
Clindamicin
Trimethoprim - except in first trimester. Make sure on folic acid
Nitrofurantoin
Co-trimoxazole - avoid if possible, but short course unlikely to cause harm
Aciclovir is safe in pregnancy
What infections should mother be screened for at booking?
Gonorrhoea Chlamydia Syphillis HIV HBV
If symptomatic -
trichomonas
genital gerpes
HCV if high risk
GBS colonises vagina and rectum in 30% of pregnant women. 1% of these will give birth to baby infected with GBS, usually presenting as pneumonia/ septicaemia
What are risk factors pointing towards GBS?
How is this prevented?
Risk factors (all require antibiotics)- previous GBS GBS bacteriuria during pregnancy PROM >18 hours maternal pyrexia delivery prior to screen (pre-term)
Routine -
Screen mothers between weeks 35-37
Treatment -
If positive, give antibiotic intra-partum, ideally 4 hours prior to delivery
- benzylpenicillin 3g (also known as penicillin G), then 1.5g 4 hourly until delivery
- cefuroxime 1.5g QDS if penicillin allergic
- clindamicin 900mg if penicillin allergic
Baby born with high risk maternal GBS.
What is treatment?
Benzypenicllin 25mg/kg BD
Gentamicin 5mg/kg OD
7 days treatment
14 days if meningitis present
Woman with PROM.
What antibiotics should be offered?
PROM should have oral erythromycin 250mg QDS (or a penicillin) for maximum 10 days or until labour starts
Asymptomatic bacteriuria is common in pregnancy (up to 15%).
All are treated, even if asymptomatic.
What are risks of this?
Risk of pyelonephritis for mother
Preterm delivery
What are TORCH organisms?
Why is term not used now?
Toxoplasmosis
Rubella
CMV
HSV
Used to all cause similar pattern of disease e.g CNS issues
Now realised that there are many more potentially infectious agents that cause neonatal disease
When does IgG cross placenta?
After 28 weeks.
Mother previous VZV with IgG produced. If baby born pre-term, not enough IgG cross placenta, so baby is susceptible
If new infection, e.g VZV in pregnancy, takes 10 days approx for IgG to be produced, and cross placenta. So if mother develops rash 7 days before to 7 days after pregnancy, baby susceptible as IgG has not crossed placenta sufficiently
What are vertical routes of HIV infection for baby?
In utero 20% risk transmission
During delivery 40% risk transmission
Breast feeding 40% risk transmission
Presenting labour, untreated HIV infection.
What are treatment options to rapidly bring down viral load?
Viral copies >1000
Tenofovir disoproxil + emtricitabine (truvada)
Tenofovir fumarate + lamivudine
Plus
Raltegravir
Plus
Atazanavir IV
Pregnant woman 16 weeks, from Bangladesh reported exposure to chickenpox.
What is next step?
Arange VZIG
Perform VZV IgG
Clarify nature of exposure
Immunise VZV
Check exposure - as possible exposure is to crusted lesions.
Check if had previously - consider immune
If not had before, check VZV IgG next. If immune, nothing else to be done
If non-immune (VZV IgG <100) -
- if within 10 days exposure, give VZIG
- After 10 days exposure, monitor for rash, and give aciclovir if rash develops to reduce risk of complications
20 weeks pregnant, USS shows small for dates.
Blood tests
CMV IgG detected
CMV IgM detected
What is next test to do?
CMV DNA PCR
CMV avidity
CMV IgM/IgG on booking bloods
CMV IgM/IgG on booking bloods will help tell when infection occurred.
IgM can persist for long time, so if present on booking, would suggest infection before this.
Can then check CMV avidity on booking bloods, to further help clarify timing of it. If high avidity, confirms infection was further in past, and low risk congenital infection. Less useful if performing on latest bloods
Pregnant, with fever and abdominal pain. Raised CRP. Delivery within 6 hours of admission.
Blood culture show gram positive bacilli with faintly haemolytic growth. Left on bench overnight.
What is most likely organism?
Bacillus cereus Corynebacterium diptheriae Listeria monocytogenes Propionibacterium acnes Streptobacilus moniliformus
Listeria
All gram positive bacilli, but beta-haemolytic points towards listeria. Growth overnight at room temperature also points to this.
Can cause premature labour
Can cause sepsis, pneumonia, meningitis in neonate
Treatment is amoxicillin and gentamicin (this also covers E.coli which is another common neonatal infection)
Most children with respiratory illness, will be due to virus.
What are most common causes?
RSV - bronchiolitis
croup - parainfluenza/ RSV/ rhino/ entero/ boca/ corona
What can be given to high risk infants, to reduce risk of severe RSV infection?
Palivumab in patients with chronic lung/ congenital heart disease
UTI should be treated in children.
What urinalysis results would indicate treatment required?
Nitrite positive
Bacteria >10 power 4/ ml
If <3 years old, refer to paeditrician for assessment
UTI 3 days treatment
Pyelonephritis 10-14 days
10 month old has fever, and painful movement left hip. Purulent fluid aspirated.
Which species causes illness in infant, but less common in older children/ adults?
Strep pyogenes Haemophilus Kingella kingiae Staph aureus Strep pneumoniae
Kingella kingiae - gram neg rod found in oropharynx in children. Bone and joint infection often follow URTI. Very uncommon after 2 years old.
Haemophilus less common due to vaccination
Staph aureus common all age groups
