Enterococcus, Listeria, and Bacillus

path micro exam 2

what is the general gram staining for enterococcus?

gram positive non-motile cocci in pairs or chains

what are capnophiles?

require CO2

which blood agar does enterococcus grow well?

enriched sheep blood agar

how does enterococcus look on blood agar?

nonhemolytic or alpha hemolytic

what does enterococcus fermentation produce?

lactic acid

what conditions can enterococcus still grow in ?

high NaCl conc. (6.5%) and in bile salts

which species are found in large intestine in high conc?

E. faecalis and E. Faecium

what is E. gallinarum and E. casseliflavus resistant to?

vancomycin

what is the pathogenesis/virulence of enterococcus?

does not have a potent toxin nor well defined vf

• COLONIZATION

what aids in adherence of enterococcus to tissues?

surface proteins —> biofilm formation

how does enterococcus gain antibiotic resistance?

acquisition of resistance genes (ez due to biofilm)

enterococcus is one of the most cause of ____ infections?

nosocomial

what are clinical diseases from enterococcus?

UTI

peritonitis

endocarditis

how can enterococcus be differentiated from pneumococcus?

• optochin resistance

• bile insolubility

• positve PYR test

how can enterococcus be treated?

aminoglycoside + cell wall inhibitor

what crucial for treatment of enterococcus?

susceptibility testing, bc of resistance

what is the gram stain of Listeria monocytogenes?

gram positive short rods

how does L. monocytogenes move?

tumbling!

what kind of temps can L. monocytogenes grow in?

cold - 4 C

how does L. monocytogenes look like on blood agar?

weak beta-hemolytic

how are the virulence factors of L. monocytogenes activated?

low pH, from acid of phagolysosome

what does the acidic pH of the phagolysosome activate? (in L. monocytogenes)

listeriolysin O

(2) phospholipase C enzymes

what does listeriolysin O do?

cytolysin that forms pores

hows does L. monocytogenes move cell to cell?

by actin rockets

in L. monocytogenes, what clinical dieases does it cause in neonates?

• early-onset (transplacentally)

  • granulamtosis infantiseptica (abscessed everywhere)

• late-onset (after birth)

what trimester does L. monocytogenes infection usually occur in preg. ppl?

third trimester

what can be used to diagnose and identify L. monocytogenes?

MALDI-TOF

how can L. monocytogenes be treated?

gentamicin w/ penicillin or ampicillin

TMP-SMX: trimethoprim/sulfamethoxazole

what is L. monocytogenes naturally resistant to?

cephalosporins

all bacillus share the ability of…

forming spores

what is the gram staining of Bacillus anthracis?

large gram positive rods

what are the thre major routes of infection of B. anthracis?

• inhalation

• ingestion

• inoculation

what are the 3 toxin protein components found on virulent strain of B. anthracis on a plasmid?

• protective antigen (PA)

• Edema factor (EF)

• Lethal factor (LF)

what is the edema factor?

calmodulin-dependent adenylate cyclase

what does the EF do?

increase intracellular cAMP levels → edema, fluid accumulation

what is the lethal factor?

zinc-dependent protease

what does the LF do?

cleaves MAP kinase → cell death (stims. macrophages to release pro inflammatory cytokines)

what makes up the edema toxin?

pa + ef

what makes the lethal toxin?

pa + lf

out of the 3 toxin proteins, in B. anthracis, which is the most immunogenic

PA

how does ef/lf get inside cell?

1. PA binds to cell surface

2. PA is cleaved

3. PA fragments bind to LF/EF

4. binding complex stims endocytosis

5. goes thru transmembrane pore

what is the polypeptide of B. anthracis made of and how is it unique?

poly-D-glutamic acid, b/c most are made of polysaccharides

what are clincal disease of B. anthracis?

• cutaneous anthrax

• gastrointestinal anthrax

• inhalation anthrax

what is a characteristic of the second stage of inhalation anthrax?

massive enlargement of mediastinal lymph nodes (sternum growth)

how to treat B. anthracis?

doxycycline or ciprofloxacin and additional antibiotics

what food is B. cereus found in?

RICE= emetic, meat and veggies = diarrhea

what are clinical diseases of B. cereus?

vomiting disease (emetic form)

diarrheal disease

ocular infections - dirty object penetrating eye

endocarditis - dirty needles

which toxin is relative to the emetic form of B. cereus?

heat-stable, proteolysis resistant enterotoxin

which toxin is relative to the diarrheal form of B. cereus?

heat labile enterotoxin

what does the heat labile enterotoxin in B. cereus do?

stims adenylate cyclase-cAMP sys in intestinal epithelial cells

which toxin is relative to ocular infections of B. cereus?

necrotic toxin, cereolysin, phospholipase C (rapid destruction)

in B. cereus, the emetic form has a ___ incubation, while the diarrheal form has a ____ incubation

short, long