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Medical Microbiology and Virology > 24 Obstetric and perinatal infections > Flashcards

24 Obstetric and perinatal infections Flashcards

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1
Q

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?

A

Malaria

Viral hepatitis

Influenza

Polio

UTI/ pyelonephritis more common

Listeriosis

Coccidiomycoses

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2
Q

Foetus has very immature immune system. This is to prevent foetal immune response to mother

What are the defects?

A

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

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3
Q

What are congenital defects if infected foetus?

CMV

Zika

A

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

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4
Q

What are congenital defects if infected foetus?

VZV

HSV

A

VZV - skin lesions, limb deformities, CNS abnormalities

HSV - disseminated infection - including encephalitis

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5
Q

What are congenital defects if infected foetus?

Listeria

Wide variety of animals carry listeria. Contact with animals/ faeces/ unpasteurised milk/ cheese can spread infection

A

Listeria - pneumonia, meningitis

Infection also occurs during and immediately after birth

Causes mild influenza like illness in mother

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6
Q

What are congenital defects if infected foetus?

Rubella

A

Does not direct damage, but interferes with mitosis

LBW

Cataract

mental retardation

IDDM - virus replicates in pancreas

heart defects

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7
Q

How to diagnose congenital rubella?

A

Maternal IgG/ IgM and RNA PCR

Neonate IgM and RNA PCR in cord blood
Neonate PCR throat swab/ urine

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8
Q

Baby with hearing/ eye defects needs investigation for CMV.

How is it diagnoses?

A

Maternal IgG/ IgM and DNA PCR

Neonate IgM within 3 weeks of delivery
Neonate DNA PCR in blood/ urine/ saliva

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9
Q

Zika virus is a flavivirus. What are other flaviviruses?

A

Yellow fever
Dengue
West Nile virus

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10
Q

What is vector for zika?

80% of infections are asymptomatic

A

Aedes aegypti

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11
Q

What are congenital effects of zika?

A

Microcephaly

Eye defects

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12
Q

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

A

epilepsy

micocephaly

mental retardation

chorioretinitis

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13
Q

Mother suspected of toxoplasma infection in pregnancy.

What is treatment?

A

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

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14
Q

Chagas disease can be spread verticlaly, and via blood transfusion. Normally spread by reduvii bug.

What symptoms can it cause foetus?

A

prematurity

LBW

anaemia

hepatosplenomegaly

meningoencephalitis

If untreated can cause cardiac/ gastrointestinal complications in 20-30 years

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15
Q

Infections can also occur during/ after birth for neonate.

Risk increased if PROM. What is definition?

A

rupture of membranes for >18 hours before labour onset

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16
Q

Which organisms are transmitted during delivery?

A

GBS - sepsis

E. coli/ klebsiella/ proteus

Staph

Gonococci - opthalmia neonatorum

chlamydia - conjunctivitis, pneumonia

HSV - disseminated

HIV

17
Q

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?

A

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
18
Q

HCV has little vertical transmission.

On the other hand, HBV has high vertical transmission rate.

How to prevent transmission to baby?

A

Give baby vaccine and HBIG immediately after birth

Give mother HBIG if highly infectious prior to delivery

19
Q

Staph aureus can cause neonatal infection. What is the usual clinical picture?

A

Toxin produced can cause scaled skin syndrome

20
Q

What are risks to umbilical stump?

A

Tetanus - resource poor countries use dirty tools to cut

21
Q

Which antibiotics are absolutely contraindicated in pregnancy?

A

Tetracyclines - tooth/ bone defects

Quinolones - cartilage damage

Clarithromycin - birth defects. Other macrolides are safe

Aminoglycosides - ototoxicity

Chloramphenicol - gray baby syndrome

22
Q

Which antibiotics are considered safe in pregnancy?

A

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

23
Q

What infections should mother be screened for at booking?

A 
Gonorrhoea
Chlamydia
Syphillis
HIV
HBV

If symptomatic -
trichomonas
genital gerpes

HCV if high risk

24
Q

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?

A 
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
25
Q

Baby born with high risk maternal GBS.

What is treatment?

A

Benzypenicllin 25mg/kg BD
Gentamicin 5mg/kg OD

7 days treatment

14 days if meningitis present

26
Q

Woman with PROM.

What antibiotics should be offered?

A

PROM should have oral erythromycin 250mg QDS (or a penicillin) for maximum 10 days or until labour starts

27
Q

Asymptomatic bacteriuria is common in pregnancy (up to 15%).

All are treated, even if asymptomatic.

What are risks of this?

A

Risk of pyelonephritis for mother

Preterm delivery

28
Q

What are TORCH organisms?

Why is term not used now?

A

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

29
Q

When does IgG cross placenta?

A

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

30
Q

What are vertical routes of HIV infection for baby?

A

In utero 20% risk transmission

During delivery 40% risk transmission

Breast feeding 40% risk transmission

31
Q

Presenting labour, untreated HIV infection.

What are treatment options to rapidly bring down viral load?

Viral copies >1000

A

Tenofovir disoproxil + emtricitabine (truvada)
Tenofovir fumarate + lamivudine

Plus

Raltegravir

Plus

Atazanavir IV

32
Q

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

A

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
33
Q

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

A

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

34
Q

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
A

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)

35
Q

Most children with respiratory illness, will be due to virus.

What are most common causes?

A

RSV - bronchiolitis

croup - parainfluenza/ RSV/ rhino/ entero/ boca/ corona

36
Q

What can be given to high risk infants, to reduce risk of severe RSV infection?

A

Palivumab in patients with chronic lung/ congenital heart disease

37
Q

UTI should be treated in children.

What urinalysis results would indicate treatment required?

A

Nitrite positive

Bacteria >10 power 4/ ml

If <3 years old, refer to paeditrician for assessment

UTI 3 days treatment
Pyelonephritis 10-14 days

38
Q

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
A

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

Medical Microbiology and Virology (60 decks)

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