Infections (Obs): GBS, HIV, Chickenpox Flashcards
What is Group B Strep?
GBs is the most common cause of early onset <7d infection in neonates.
What is the aetiology of Group B Strep?
Commensal bacterium in vagina and rectum in 25% women. Most babies in contact will not be affected. Some will be colonised, some will be seriously ill (<12h post delivery usually).
Positive HSV/LVS/rectal swab/MSU, previously affected baby, preterm, PROM, PTL.
What is the epidemiology of Group B Strep?
Most frequent cause of early onset neonatal infection, 0.5/1000 births UK.
What is the history/ exam of Group B Strep?
Asymptomatic, detected on MSU, HVS or LVS. PROM. PTL.
What is the pathology of Group B Strep?
G+Strep, BpB Lancefield antigen. Strep Algacitiae.
What investigations do you do for Group B Strep?
Micorbiology: LVS/HVS/rectal swab/MCS. No national screening program.
What is the management of Group B Strep?
IV antibiotics in labour (benzylpenicillin OR clindamycin if allergic). If detected antenatally with MSU.
What are the complications/ prognosis of Group B Strep?
Neonatal septicaemia, pneumonia, meningitis, death
Tx 80% effective in preventing GBS within 12h postpartum (early onset). No effect on delayed infection. (check this fact)
What is HIV?
Virus attacking T lymphocytes.
What is the aetiology/epidemiology of HIV?
HIV present in vaginal fluid, semen, blood and breast milk. Transmitted by sexual contact, blood or vertical.
Increased risk in vertical transmission if viral load high, CD4 count low, PROM, breastfeed.
Increasingly common due to increased life espectancy of HIV+.
What is the history/ exam of HIV?
Asymptomatic until AIDS (8-10y). ?Febrile seroconversion.
No clinival features in HIV. May present with infections, rarely with AIDS defining illness (KAP sarc, PCP, oesophageal candidiasis).
What is the pathology of HIV?
80% transmission in 3rd trimester in non breastfeeders. 2% in the first two trimesters.
What investigations do you do for HIV?
Blood: routine HIV screen and blood count, viral load.
Monitor drug toxicity: FBC, UE, LFT, lactate and blood glucose.
What is the management of HIV?
Antenatal: good control, HAART if CD4>350. Suppress viral to aim of <50 copies/mL.
Intrapartum: if viral load detectable or non compliant, advise C section. IV ZDVD infusion from 4h prior to C section.
Viral load undetectable: consider vaginal delivery, avoid FBS/FSE or rupture or membranes for >4h.
Neonatal:
· antiretrovirals for 4-6wk,
· PCR test at birth, 3wk, 6wk, 6mo,
· HIV ab test at 18m.
What are the complications/ prognosis of HIV?
Side effect of HAARTI: PPREC, Ob cholestasis, liver issues, lactic acidosis, glucose intolerance/GDM. Transmisson rate can be reduced from 28% ro 2% medically.
What is Chickenpox?
Primary infection with VZV.
What is the aetiology of Chickenpox?
Transmitted by physical contact, aerosol, vertical.
NO prior immunity, contact, immigration from tropical/subtropical areas.
What is the epidemiology of Chickenpox?
3/1000 pregnancies.
What is the history/ exam of Chickenpox?
Fever, malaise, pruritic rash (vescicular then crusts over)
Vescicular pleiomorphic rash
What is the pathology of Chickenpox?
Highly infectious Dna virus
SpreadL aerosol, direct contact with vescicle fluid, indirect fomite.
Incubation: 1-3wk, infectious from 48h before rash to after all crusted.
Dormant period: following primary infection the virus lies dormant in sensory nerve ganglia, may reactivate.
What investigations do you do for Chickenpox?
Blood: VZV IgM in the acute phase, IgG to check immunity.
USS: fetal antenatal anomaly scan (fetal varicella syndrome)
What is the management of Chickenpox?
Non immune mother: VZVIG (reduces chance by 50% after exposure)
Established VZV: Aciclovie, if within 24h of rash onset.
Maternal infection near term: avoid elective delivery for 5-7 days from the appearanche of rash (placental transfer of maternal Ab over 5-7d)
Neonate: VZVIG if delivered within 7d of rash onset, before or after.
What are the complications/ prognosis of Chickenpox?
Maternal pneumonia (10%, only in prengnat women!), hepatitis, encephalitis, death.
Fetal varicella syndrome: if maternal infection before 28wk, skin scar, eye defects, neuro defects, limb deformities.
Neonatal: VZV infection in the newborn (if maternal infection 1-4wk before delivery to 1wk after.
