Etiologic agents predominately seen neonate Flashcards by Shaun Mehdi

what is the gram staining of s. agalactiae?

gram-postive cocci in chains or pairs

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what is the hemolytic status of s. agalactiae on sheep blood agar?

beta-hemolytic

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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

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s. agalactiae serologically is based on what

capsular polysaccharide

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what is s. agalactiae virulence factor

capsular polysaccharide- antiphagocytic

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for neonates and young infants what is the leading cause of bactermia alone or with meningitis with first 3 months

s. agalactiae

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what ratio of pregnant women in counter invasive GBS

1/3

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what other populations are effected by GBS

people >60yo and

diabetics, cirrhosis , malignancy and AIDS

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in what tissues can GBS syndromes occur?

virtually all

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how can GBS be transmitted

vertically during birth or horizontally from mother after birth

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where does GBS colonize

mothers pharynx, vagina, and skin via rectal colonization

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what is age and gender is most affected by GBS meningitis

neonates

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what is the seasonality of GBS

none

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what are the RF for GBS

LBW and material related events( I.E infections)

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what two GBS forms of disease are recognized in neonatal infections

Early onset sepsis (bacteremia)

late onset sepsis (bacteremia and focal event)

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how is acute onset GBS sepsis decribed

occurs within 6 days of birth

mother is source occurs in utero

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how is late onset GBS sepsis defined

occurs week to 3 months after birth

source: postpartum in nursery, community or mother

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what are focal infections in late onset GBS sepsis

meningitis
cellulitis
osteomyelitis
septic arthritis

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what is more common early or late onset GBS sepsis

early

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meningitis occurs more commonly in early or late onset GBS sepsis

late

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How to diagnose GBS

isolate from neonate (CSF, Blood, Lungs)
isolate from mother (vagina, pharynx, GI, skin)
do a rapid slide agglutination or PCR

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what is the treatment for GBS

Penicillin G

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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)

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what is the prevention for late onset GBS infection

NONE

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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?

what type of pathogen is listeria monocytogenes?

facultative intracellular pathogen

what two ways does listeria monocytogenes invade

1. invade and multiply in non-professional macrophages (epithelial and endothelial) 2. 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

1. food-borne: rare but high mortality 2. human to human: in utero or parturition 3. 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

1. early onset sepsis 2. spontaneous abortion 3. still born 4. 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

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 ```