Enterobacterales: Characteristics, Gram Stains, Virulence, and Resistance

what are the characteristics of enterobacterales (-) (5 points)

1. ferment glucose 2. reduce nitrate to nitrite 3. catalase + 4. oxidase negative 5.some resistant to bile salts

What color stain is gram negative? how many membranes? how many peptidoglycan structures?

pink, 2, 1

What color stain is gram positive? how many membranes? how many peptidoglycan structures?

purple, 1, 4

which gram produces endotoxins? (+ or -)

gram negative (pink)

which gram produces exotoxins? (+ or -)

gram positive (purple)

what are the 3 virulence factors you need to know for enterobacterales?

1. endotoxins (gram - pink)

2. capsule (no phagocytosis)

3. antimicrobial resistance

who makes the best flash cards

Sandra

Tell me about enterobacterales endotoxins

theyre the lipopolysaccrides on the outer layer. cause lethal shock. activate complement and release cytokines, leukocytes, can cause thrombocytopenia etc etc

Tell me about enterobacterales capsule

the capsule has hydrophilic antigens that repel, however some people have natural anti capsular antibodies

is enterbacterales an aerobe or anaerobe?

facultative anaerobe

where do you find e coli in the body

urinary tract

is blood agar sterile or non sterile

sterile (non selective)

is macconkey sterile or non sterile

non sterile (selective media)

what are the 2 biochemical test you need to know

1.oxidase test 2. spot indole test

what is the decolorizer in gram staining

acetone or ethyl alcohol

REVIEW: what are all the oxidase negatives we went over? (9) (non lactose fermentors)

1. acinetobacter (baumannii)

2. salmonella spp

3. stenotrophomonas

4. shigella (dysenteriae)

5. proteus spp

6. providencia spp

7 .serratia (marcescens)

8. yersinia (pesitis, entercolitica)

9. morganella spp

REVIEW: what are all the organism we can do catalase testing on? (5)

1. pseudomonas aeroginosa

2. stenotrophomonas

3. moraxella catarrhalis

4. burkholderia (psuedomallesi and cepacia)

5.neisseria (gonorrhoeae, meningitidis)

REVIEW: what are all the oxidase positives we went over? (4) (non lactose fermentors)

1.psuedomonas

2. moraxella (catarrhalis)

3. vibrio (cholerae, vulnificus, parahaemolyticus)

4. Burkholderia (cepcia, and psuedomallei)

REVIEW: what are all the indole positives we went over? (2)

1. e coli

a. ETEC b. EPEC c. EAEC d. STEC e. EIEC

2. klebsiella oxytoca

REVIEW: what are all the indole negatives we went over? (4)

1. enterobacter cloacae

2. citrobacter freundii

3.klebsiella aerogenes

4. klebsiella pnuemoniae

REVIEW: What are all the fastidious organisms we learned? (3)

1. haemophilus

2.campylobacter

3. helicobacter pylori

what are the selective ingredients in macconkey agar

bile salts and crystal violet (kills +)

what are the differential ingredients in macconkey agar

lactose

If there is growth on the pink side of Macconkey, what does that mean?

lactose +

If there is growth on the yellow side of Macconkey, what does that mean?

lactose -

what is the reagent in spot indole test?

tryptophan (product is indole)

what is the reagent in oxidase test?

TPP (product is cytochrome C oxidase enzyme)

what is the most organism that causes UTI

e coli

physical description of ecoli

circular, hemolysis in blood, metallic

what are the 5 ecoli strains?

1. ETEC

2. EPEC

3. EAEV

4. STEC

5. EIEC

Describe ETEC: minimum 2 points

small intestine, NONBLOODY diarrhea, travelers diarrhea, developing countries, PLASMID MEDIATED ENTEROTOXINS

Describe EPEC: minimum 2 points

small intestine, NONBLOODY diarrhea, PLASMID MEDIATED ATTACHMENT TO MICROVILLUS, invade epithelial cells

Describe EAEC: minimum 2 points

small intestine, developing and some developed countries, travelers diarrhea, growth retardation in children, FEVER, NONBLOODY diarrhea, AUTOAGGLUTINATION "stacked bricks", fecal-oral

Describe STEC: minimum 2 points

consumption of UNDERCOOKED meat, large intestine, can be spread person to person, BLOODY diarrhea, STX1 STX2 disrupt protein synthesis

Describe EIEC: minimum 2 points

rare, NONBLOODY diarrhea, rarely dysenteric, PLASMID MEDIATED TO MICROVILLI, invade epithelial cells, fecal-oral

4 mechanisms of antibiotic resistance

1. more med efflux pumps

2. inactivating enzymes

3.reduce protein channels or increase selectivity

4. mutations

What are the 2 organisms with resistance charts you need to know

1. ecoli

2.psuedomonas

how does ecoli resist beta lactams? (3)

enzyme inactivation:

beta-lactamases

1. ESBL

2.AmpC

3. carbapenemase

how does e coli resist fluoroquinolnes? (2)

mutation

1. topoisomerase (2) (gyraseA)

2. topoisomerase IV (parC)

how does ecoli resist aminoglycosides?

enzyme inactivation:

acetyltransferase

how does ecoli resist sulfonamides?

mutation

dihydrofolate reductase

how does ecoli resist tetracyclines?

more med efflux pumps:

tet gene encoding

what is the predominant mechanism of resistance in gram -?

betalactamse resistance

is klebsiella spp a lactose fermentor?

yes

what tests would you do to identify klebsiella

macconkey and spot indole

what are the 3 klebsiella?

oxytoca (indole +)

aerogenes (indole -)

pneumoniae (indole -)

what color is klebsiella spp. on in macconkey?

pink

main physical characteristic of klebsiella spp. ? (1)

mucoid (slime)

what is the name of the gene in Klebsiella spp. that codes for the carbapenamase? (resistance gene)

blackKPC

main physical characteristics of enterobacter spp. ? (2)

(THIS IS NOT THE SAME AS ENTEROBACTERALIS)

raised, no sheen

is enterobacter a lactose fermenter?

yes

is enterobacter indole positive of negative?

negative

what tests would you do to identify enterobacter spp?

macconkey and indole

what is the only enterobacter we need to know?

enterobacter cloacae

What are the two citrobacter you should recognize? (2)

citrobacter freundii

citrobacter koseri

EXCEPTION: citrobacter koseri

not a lactose fermentor (so it will be colorless on macconkey agar)

is citrobacter spp citrate + or -?

+

what tests would you do to identify citrobacter spp?

macconkey, indole, citrate

which of the citrobacters is indole negative?

citrobacter freundii

NOT ON TEST: which of the citrobacters is indole positive?

citrobacter koseri

where can you find serrtia spp?

bathtub sinks

main physical characteristic of serratia spp. ? (1)

theyre pink/red

is seratia spp oxidase + or -?

negative

is serratia spp a lactose fermentor?

no (slow)

what color would serratia be on the macconkey?

colorless

what tests would you do to identify serratia spp?

macconkey, oxidase

enterobacter, citrobacter, and serratia are grouped together in resistance

what is thier specific resistance mechanism?

enzyme inactivation via beta lactamase CALLED AMP-C

recall: there are 3 different kinds AMP-C, carbapenamse, and ESBL

what are the two ways enterobacter, citrobacter, and serratia become resistant?

(enterobacter, citrobacter, and serratia)

common acquisition: chromosomal AMP-C gene

rare acquisition: plasmid mediated AMP-C gene

define: common acquisition: chromosomal AMP-C gene

(enterobacter, citrobacter, and serratia)

present in thier genome 90 percent of the time, 5-30 percent chance of INDUCING resistant when exposed to 3rd gen cephalosporins

define: rare acquisition: plasmid mediated AMP-C gene

(enterobacter, citrobacter, and serratia)

"stably derepressed AMP-C", naturally resistant without induction

what are the 3 organisms that have: common acquisition: chromosomal AMP-C gene, rare acquisition: plasmid mediated AMP-C gene

(enterobacter, citrobacter, and serratia)

what is a physical characteristic of proteus spp? (1)

motile

what is a physical characteristic of providencia spp? (1)

motile

what is a physical characteristic of morganella spp? (1)

motile

what organism swarms on the agar plate? (1)

proteus spp

what are the two organisms that are urease +?

proteus and morganella

why do the the two urease + organism smell?

proteus and morganella, generate co2 and ammonia

what can proteus and morganella cause? (in your body)

kidney stones from mg2+ and ca2+ precipitate

which organism is urease - ?

providencia

what test could you do to identify morganella, providenicia, and proteus

macconkey, oxidase, urease

is morganella oxidase + or -

negative

is providencia oxidase + or -

negative

is proteus oxidase + or -

negative

would morganella, providenicia, and proteus be pink or colorless on macconkey?

colorless

is salmonella spp part of the human microbiome?

no

how is salmonella spp spread?

fecal oral, contaminated foods

what compound does salmonella produce

hydrogen sulfide

what is salmonella spp resistant to?

bile salts

is salmonella a lactose fermentor?

no

what color would salmonella spp be on the macconkey agar?

colorless

what tests can you do to identify salmonella?

macconkey, oxidase, hektoen enteric agar

what tests can you do to identify shigella?

macconkey, oxidase, hektoen enteric agar

what is the special agar for salmonella spp? what color will it be?

Hektoen Enteric Agar, black

what are all the + and - of salmonella

lactose -

sucrose -

oxidase -

h2s +

what is the special agar for shigella spp? what color will it be?

Hektoen Enteric Agar, green

what are all the + and - of shigella

lactose -

sucrose -

oxidase -

h2s -

is shigella a lactose fermentor?

no

is shigella spp oxidase - or +?

negative

is salmonella spp oxidase - or +?

negative

what are the selective ingredients of hektoen enteric agar? (5)

1. bile salts (won't kill gram negs)

2. lactose (all gram negs be salmonella and shigella)

3. sucrose (all gram negs be salmonella and shigella)

4.salicin (all gram negs be salmonella and shigella)

5.peptone (salmonella and shigella food :) )