Paediatric Microbiology

Dr Amy ChueID/Microbiology Registrar

Dr Peter MunthaliConsultant Microbiologist

Objectives

• By the end of this session you should be able to:– Distinguish between the common causes of

infections in the neonate and older children– Relate maternal infections to neonates– Interpret CSF findings in relation to clinical

presentation in neonates– Demonstrate rational use of antibiotics in

neonatal sepsis with regard to possible causative organisms

Case One

• 3 week old baby born at 39/40• Normal vaginal delivery• Healthy and feeding well initially• Upset and crying• Bulging fontanelle noted by parents• Taken to ED• Hx – admitted a week earlier with bronchiolitis

and discharged with no antibiotic treatment

Results

• CSF– Clear and colourless– RBC 84x10^6/L– WCC 236x10^6/L– Gram stain: organisms not seen– Glucose 3.1 mmol/L– Protein 1.4 g/L (0.15 – 0.45)

• FBC– Hb 101g/L (111 – 141g/L)– WCC 24.85 x 10^9/L (6 – 18.0 x 10^9/L)– CRP 46mg/L (<11mg/L)

Questions

• What is the possible microbiological diagnosis?

• What antibiotics would you consider commencing and why?

Microbiology

Management

• Amoxicillin based regime for 14 days

• Vaccination (2/12, 4/12, 12/12)

Case Two

• 1 day old baby born at 36+5

• Floppy at birth

• Mother had fever during labour and received some antibiotics

• Baby started on Cefotaxime and Amoxicillin

Investigations• LP

– Gram• Turbid CSF• RBC 6x10^6/L• WCC 1046x10^6/L 90% Poly• Glucose 1.9mmol/L• Protein 1.30g/L (0.15 – 0.45g/L)• No organism seen

• CRP 164• FBC

– HB 93g/l– WCC 13.09x10^9/L (6.0 – 18.0)

• Blood culture – Gram positive cocci ?type

Questions

• What is the diagnosis?– What is the possible microbiological

diagnosis?

• Is this infection preventable?

• Should antibiotics regime be changed?– If so, how?

Organisms

• Group B Streptococcus– Streptococcus agalactiae

Management

• Penicillin based regime (Benzylpenicillin Vs Amoxicillin)

• Prophylactic antibiotics given during labour

• Cefotaxime as blind treatment for neonate

Case Three

• 7 day old baby born at term

• Normal vaginal delivery

• Presents with fever, irritability and poor feeding

Investigations

• FBC– Hb 115g/l– WCC 24.85x10^9/L

• CRP 12

• Blood cultures: Gram positive bacilli

Questions

• What is your microbiological diagnosis?

• How would you manage the case:– Antibiotics– Infection control

Diagnosis

• Listeria monocytogenes

Listeria monocytogenes

• Gram positive bacillus

• Pregnant women particularly at risk

• Certain at risk foods

• Inherently resistant to cephalosporins

Management

• Amoxicillin for 14 - 21 days

• Infection control – isolation

Case Four

• Baby born at 38 wks, 2.6Kg

• Mother had episiotomy

• Baby discharged well on day 2

• Readmitted on day 7 with:– Wt loss– Poor feeding– Abnormal limb movements– EEG – no seizure activity

Investigations• CRP 158• CSF:

– Cell count normal– Glucose normal– Protein 0.85g/L (0.15-0.45g/L)

• Clotting deranged• Low platelets• LFTs deranged• CT: extensive bleeding on brain and evidence of

hypoxic injuries

Treatment

• Initial treatment: Benzylpenicillin and Gentamicin

• Modified treatment: Meropenem and Vancomycin

Further investigations and treatment

• What further investigations should be done– On CSF– On Blood

• What is the possible diagnosis?

• Is the current antibiotic regime adequate?

Further Results

• CSF PCR – HSV 1 positive

• Blood PCR – HSV 1 positive

HSV infection in neonates

• Usually peri natal and post natal– 45% skin, eyes and mouth infections– 20% CNS infection– 25% disseminated HSV

• Symptoms• Irritability• Seizures• Respiratory distress• Jaundice• Coagulopathy• Pneumonitis

HSV in neonates

• Rx high dose aciclovir

• Rx women with lesions– Suppressive therapy

• Consideration of C-section

• BASHH guidelines

Key points

• Possible organisms causing neonatal sepsis– Group B Streptococcus– Group A Streptococcus– E.coli– Listeria monocytogenes

• Antibiotic treatment– If Listeria is suspected, must consider penicillin based

regime

• Important to consider maternal infection