Etiologic agents predominately seen neonate Flashcards
what is the gram staining of s. agalactiae?
gram-postive cocci in chains or pairs
what is the hemolytic status of s. agalactiae on sheep blood agar?
beta-hemolytic
what is the status of s. agalactiae when exposed to bacitracin and how does it differ from GAS
bacitracin resistant unlike GAS which is sensitive
s. agalactiae serologically is based on what
capsular polysaccharide
what is s. agalactiae virulence factor
capsular polysaccharide- antiphagocytic
for neonates and young infants what is the leading cause of bactermia alone or with meningitis with first 3 months
s. agalactiae
what ratio of pregnant women in counter invasive GBS
1/3
what other populations are effected by GBS
people >60yo and
diabetics, cirrhosis , malignancy and AIDS
in what tissues can GBS syndromes occur?
virtually all
how can GBS be transmitted
vertically during birth or horizontally from mother after birth
where does GBS colonize
mothers pharynx, vagina, and skin via rectal colonization
what is age and gender is most affected by GBS meningitis
neonates
what is the seasonality of GBS
none
what are the RF for GBS
LBW and material related events( I.E infections)
what two GBS forms of disease are recognized in neonatal infections
Early onset sepsis (bacteremia)
late onset sepsis (bacteremia and focal event)
how is acute onset GBS sepsis decribed
occurs within 6 days of birth
mother is source occurs in utero
how is late onset GBS sepsis defined
occurs week to 3 months after birth
source: postpartum in nursery, community or mother
what are focal infections in late onset GBS sepsis
meningitis
cellulitis
osteomyelitis
septic arthritis
what is more common early or late onset GBS sepsis
early
meningitis occurs more commonly in early or late onset GBS sepsis
late
How to diagnose GBS
isolate from neonate (CSF, Blood, Lungs)
isolate from mother (vagina, pharynx, GI, skin)
do a rapid slide agglutination or PCR
what is the treatment for GBS
Penicillin G
what is the prevention for early onset GBS infection
- screen mother
- IV AB to mother preterm and at labor
- AB to mothers who have RF for GBS (premature membrane rupture)
what is the prevention for late onset GBS infection
NONE
what effect on etiology can intrapartum AB have on neonate
cause of infections switches from GBS to E.Coli
what is the gram staining of listeria monocytogenes
gram positive coccobacilli, motile and cornyeform
is listeria monocytogenes fastidious?
NO
what type of pathogen is listeria monocytogenes?
facultative intracellular pathogen
what two ways does listeria monocytogenes invade
- invade and multiply in non-professional macrophages (epithelial and endothelial)
- survive and multiply with phagocytic cells
what re the two virulence factors for listeria monocytogenes
lipoteichic acids- endotoxin
proteins- organism-directed phagocytosis and cell to cell spead
what is the incidence of listeria monocytogenes
sporadic and food-borne epidemics
how is listeria monocytogenes transmitted
- food-borne: rare but high mortality
- human to human: in utero or parturition
- zoonosis
what is the reservoir for listeria monocytogenes
soil, water, fecal flora, food
what is the age and gender associated with listeria monocytogenes disease
pregnant women are are increase risk
what is the seasonality of listeria monocytogenes
summer
what are the RF for listeria monocytogenes
T cell suppression
what is the simple pathogenesis of listeria monocytogenes
Organism ingested -> pases through intestinal epithelium -> bacteremia
what is the POE for listeria monocytogenes
GIT
what is the purpose of listeriolysin O?
disrupts phagosome membrane allowing listeria cells to escape
what is the incubation time for listeria monocytogenes
~30 days
What possible immunity is there to listeria monocytogenes
primarily t-dependent immunity
what is the clinical syndrome of listeria monocytogenes in pregnancy
illness usually occurs at 3rd trimester
mother has flu-like symptoms rarely any CNS
what is the clinical syndrome of listeria monocytogenes in utero
- early onset sepsis
- spontaneous abortion
- still born
- premature births
mortality is high
what two organs has the most concentration listeria in early onset sepsis found?
LUNG and GUT
what is granulomatosis infantisepticum
rare condition of disseminated abscess or granulomas in multiple organs with papules in throat and skin
mortality is high!
what is the clinical syndrome of listeria monocytogenes in late onset sepsis
occurs during or after birth
symptoms start 1-2 weeks after birth
mortality is moderate
mother is asymptomatic
how is listeria monocytogenes diagnosed
Culture, Gram stain, CSF
what environment is best to culture listeria monocytogenes
cold-enrichment
what limitations are there to gram stain listeria monocytogenes
similar to corneybacterium, easily decolorized, small number
what is seen in CSF of listeria monocytogenes
monocyte predominante
glucose normal
low probability of visualizing listeria so leads to misdiagnosis
what is the treatment of listeria monocytogenes
ampicillin and gentamycin alternative is tmp-smx
what is the gram staining of e.coli
gram negative rod enteric and a coliform
is e- coli oxidase positive or negative
oxidase negative
which strain of e.coli causes the majority of UTI in humans
Extraintestinal pathogenic e. coli (ExPEC)
what is the most important virulance factor of e. coli in meningitis cases
K1
what does K1 in e.coli strains refer to
capsular serotype
what is the K1 serotype in e.coli responsible for
anti-phagocytic to neutophils
What type of pathogen is e.coli
facultative intracellular pathogen of macrophages and monocytes
what is the incidence level of e. coli
HIGH
2nd most common cause of invasive disease in neonate
most common gram-negative agent in neonatal meningitis
there is a
what affect can e.coli k1 vaginal colonization have on a pregnant female
increases chances of preterm
what is the source of e.coli k1 infection
mother’s colon
how do you diagnose E.coli k1
culture and ID
what other gram negative agents can cause systemic infections in neonate
klebsiella pneumoniae and pseudomonas aeruginosa
klebsiella pneumoniae and pseudomonas aeruginosa occurs in what type of neonate
VLBW
what other Gram Positive agents that can cause systemic infections in neonates
staphlococcus epidermidis (CoNS) which causes early onset sepsis and meningitis
what neonate diseases can klebsiella pneumoniae cause
early and late onset sepsis. easy to culure and ID
what viruses can cause infection and morbidity in neonates
CMV HSV 1/2 HHV 6/7 non-polio enterovirus - neonatal sepsis HMV and laryngeal warts LCMV
