Postnatal Infx

Question 1

E. coli

Answer 1

Postnatal Infx
• small G(-) bacilli
• motile
• urease –
• nitrite +
• *rapid lactose  fermentor
• *NMEC = neonatal meningitis E. coli
• *Most frequent cause of *early onset sepsis in very-low birth weight (VLBW) infants
- *most common cause of mortality
• Usually acquired from mother at or just before birth
Virulence
- *K1 capsular antigen
- adhesins
- pili

Question 2

Staphylococcus epidermididis

Answer 2

Postnatal Infx
o Gr (+) cocci, in clusters
o Catalase (+)
o Coagulase (-) 
o Mannitol Fermentation (-) 
• Likely acquired from direct or indirect contact or from infant’s own skin
- most commonly isolated pathogen among low birth weight infants with *late onset sepsis.
Virulence
- *biofilms
- *coagulase-
- *slime layer - can stick to plastics
- adhesions
Tx
- *resistant to penicillin, so give vanco

Question 3

Staphylococcus aureus

Answer 3

Postnatal Infx
o Gr (+) cocci, in *clusters
- capsule
- *Coagulase (+)
- catalase+
• Less common than CoNS in *late onset sepsis; but higher mortality rate
• Usually HAI of VLBW; direct or indirect transmission
• No difference between MRSA and MSSA in terms of morbidity, mortality & length of hospital stay
Virulence
- *invasins
- *adhesions
- *protein A
- *fibronectin-binding protein
Tx
- vanco!

Question 4

Candida albicans

Answer 4

Postnatal Infx
- Dimorphic fungus
• Opportunistic; takes advantage of a lack of immune defenses in VLBW infants
- *germ tube test
Disease
• Systemic infections = *candidemia
   • Sepsis
   • Invasive focal infections
• Mucocutaneous candidiasis 
• Catheter-related infections 
Risk factors
• Extreme prematurity
• Broad Spectrum Antibiotic exposure (esp. 3rd gen cephalosporin) 
• Central venous catheters
Virulence
- *biofilms