Enterobacterales - less clinically important Flashcards
What are the culture characteristics of Proteus spp?
1) grow on MAC but do not swarm
2) May have intrinsic resistance features
TiNC
Tetracycline
imipenem
Nitrofurantoin
Colistin
*These are slightly more common pathogens
What disease is associated with Proteus spp?
UTIs
Formation of Kidney stones
They produce ammonia from urea
Do Proteus have intrinsic resistance?
yes, TiNC and They have AmpC beta lactamases
Ampicillin
1-2nd Gen cephalosporins
Tetracycline
imipenem (without carbapenemases) increased MICs but not intrinsically resistant
Nitrofurantoin
Colistin
Need to confirm with CLSI appendix B
Who are the members of the Proteeae and what do they have in common?
Proteus
Providencia
Morganella
TNC intrinsic resistance
Clinically relevant Morganella and Providencia spp?
Providencia rettgeri
Providencia stuartii
Morganella morganii
*These are slightly more common pathogens
Which bacteria sometimes produces red pigment?
Serratia marcescens
*These are slightly more common pathogens
Enterobacter cloacae complex
Enterobacter cloacae, E. asburiae, E. hormaechei, E. kobei
*These are slightly more common pathogens
Who has chromosomal AmpC beta-lactamases?
SPACE-MK
SPACE-MK
Serratia marcescens
Proteeae (+), Pseudomonas
Acinetobacter, Aeromonas
Citrobacter freundii, Chromobacterium
Enterobacter cloace
Morganella morganii
Klebsiella aerogenes (prev enterobacter)
Which antibiotics do not work on bacteria with AmpC beta-lactamases?
1st, 2nd, and 3rd generation cephalosporins
most penicillins, and β-lactamase inhibitor-β-lactam combinations
AmpC possibilities
1) repressed, not expressed
2) expressed at low levels
3) expressed at high levels
How to isolate/culture Salmonella?
1) BAP
2) MAC - NLF
3) H2S positive hektoen enteric agar
4) Xylose lysine deoxycholate agar (XLD agar) black colonies due to hydrogen sulfide production
Bone marrow cells is the gold standard
How do distinguish Samonella from other spp?
Xylose lysine deoxycholate agar (XLD agar)
hektoen enteric aga
Based of hydrogen sulfide production
Who are natural reservoirs of Salmonella?
1) reptiles-specially turtles
2) birds
Typhoidal Salmonella serotypes?
Salmonella Typhi (typhoid fever)
Salmonella Paratyphi A, B, C (paratyphoid fever)
What are the Typhoid fever symptoms? and how is it diagnosed?
high fever (103 to 104°F )
headache
abdominal pain
GI illness
rash spots on abdomen, chest, back
Blood culture
Stool
Salmonella spp not typhi are confirmed by which chemical reactions?
ODC ornithine decarboxylase +
Citrate +
Salmonella Typhi is resistant to what?
1st and 2nd generation cephalosporins, and aminoglycosides (gentamicin, amikacin, tobramycin)
Which bacteria is genetically indistinguishable from E. coli?
Shigella
MALDI cant differentiate them - > need to do an indole/motility test or run the biochemicals on the Vitek
How is Shigella biochemically diff than E. coli?
Shigella can’t ferment lactose
Indole neg
Not motile
E. coli is positive for all 3
What disease does Shigella spp cause?
Shigellosis
Self limiting diarrhea but may be a long course
risk factors include poor sanitation, contaminated food, young children in daycares, immune compromised ppl,
Salmonella/Shigella/E. coli selective media
Hektoen Enteric Agar
Salmonella produce H2S = black
E. coli ferment lactose = orange
Shigella do not ferment lactose = colorless
Salmonella/Shigella selective media
Xylose Lysine Desoxycholate Agar
Desoxycholate inhibits non-enterics
Salmonella = black H2S production
Name the Yesernia spp and disease that they cause
Y. enterocolitica (most common)
Y. pseudotuberculosis (less common)
Foodborne and associated with undercooked pork
or acquired from animals
Name other opportunistic GI pathogens (5 major ones) CAPEH
1) Citrobacter (plates small really bad) - strong lactose fermenter, UTI, meningitis
Citrobacter freundii strains have inducible ampC
2) Plesiomonas shigelloides - in freshwater fish, self-limiting GI disease
3) Aeromonas hydrophila- skin and soft tissue infection too, necrotizing fasciitis
4) Hafnia alvei-GI commensal but can cause disease in immunocompromised
5) Edwardsiella species
Salmonella nontyphi serotypes
Species and Serotype
Salmonella Enteriditis
Salmonella Thyphimurium
And many others
