Gram Negative Bacilli and coccobacilli mix Flashcards
Name 5 important gram-negative organisms that are not Enterobacterialis,coming from aquatic sources, and one related that is found in the human stomach
Vibrio, Aeromonas, Plesiomonas, Campylobacter, and Helicobacter (the last one)
How does Aeromonas hydrophila appear on SBA and MAC?, and what is its oxidase and indole status?
Large, round raised and opaque with strong beta hemolysis; ferments lactose like E. coli; is OX POS and IND POS
WHat distinguishes Aeromonads from Enteric bacteria especially if showing beta-hemolysis and lactose fermentation?
They are OX pos (enterics are NEG)
On what medium will Aeromonas form pink-centered colonies from mannitol fermentation , resembling another enterobacteriaceae with a characteristic morphology?
CIN, on which Yersinia enterocolitisa (OX =) forms red bullsye, looking very similar
What are the best tests to distinguish Aeromonas from Vibrios?
The string test (Vibrios positive usu) and O/129 susceptibility (most Vibrios S, Aeromonads R); Also, growth in NaCl: Aeros and Plesios grow well with 0%, but most Vibrios can’t grow without NaCl
*** NOTE that V. cholerae (and mimicus) is nonhalophiliic so this must be done in conjunction with string and O/129!!!!!
Like Vibrios and Aeromonads, this organism is OX POS, glucose-fermenting, GNB with polar flagella, but it is now classed with the Enterobactericeae, and is the only OX positive of that group:
Plesiomonas shigelloides
Where is Plesiomonas found, generally?
mainly in FRESH and ESTAURINE waters of sub- and tropical climates bc not highly salt tolerant; also widely distributed in animals both warm and cold-blooded
IN addition to diarrheal disease, PLesiomonas can cause what kinds of disease?
infections due to animal handling, especially water animals; can lead to bacteremia or meningitis;
Aeromonas spp mainly cause what disease type? What spp is mostly associated , and what spp with more serious complications such as HUS?
Diarrheal/enteric; A. caviae; A. hydrophila and A. veronii
Between Aeromonas caviae and A. hydrophila, which is H2S and Glucose+gas positive?
A. hydrophila
Many Vibrios grow on common SBAor CHOC; describe appearance and also on MAC
Medium to Large smooth opaque colonies, iridescent with greenish hue; most pathogenic Vibrios are NLFs on MAC, but some do, so always do oxidase…or sub any suspicious LFs to SBA for next day oxidase testing
WHen might a selective media be warranted for possible Vibrio isolation and what media/how do certain spp appear?
If there is a possibilty due to seafood or seawater exposure or coastal travel; Use Thiosulfate Citrate Bile salt Sucrose, TCBS. Sucrose fermenters like V. cholerae will be yellow; non-sucrose fermenteres such as V. parahaemolyticus and most vulnificus will be green.
Which Vibrios mainily cause: cholera (and how), and food poisoning?
Cholera: V. cholerae, by a toxin that stims CAMP in intestinal cells and causes extreme secretion of electrolytes, causing massive watery diarrhea, deadly.
V. parahaemolyticus more often causes food poisoning
How are Vibrios different from Pseodomonads?
PSeudomonads don’t ferment any carbs, they are only oxidative (uncovered tube only metabolizes);
How are Vibrios different from Plesiomonads?
Plesiomonas ferments inositol but deos not ferment mannitol, sucrose, or liquify gelatin; Vibrios DO NOT ferment inositol, and do mannitol, liquify gelatin, and usually sucrose
this bacteria genus is associated with animal bite wounds and are gram-negative nonmotile, facultative anaerobic coccobacilli with better growth on CHOC; It requires cystine and is strictly aerobic….
Francisella tularensis: also it is oX and Urease negative; slow growth, may take 48 hours and need to check daily for 14 days; grows on CHOC but not blood
what is the best combo for diagnosing Legionairre’s disease?
culture on BCYE and urine antigen detection
describe staining of Legionella spp general characteristics and methods to enhance
they are weakly staining gram negative bacilli that can be both outside of and within macrophages/segs. Extending safranin time to 10 mins can help enhance stain
How are Legionella with regards to culture requirements and oxygen
they are aerobic and require L-cysteine, do not grow on SBA and may grow on CHOC as tiny colonies but BCYE agar is used for best isolation
describe the common colony morphology of Legionella and use of carbohydrate, catalase and oxidase characterisics
Young colonies have ground glass center with pink/lt blue/ or green bands on periphery; they are asaccharolytic and catalase & oxidase WEAKLY positive
Legionella can be grouped by colors due to what phenomenon; what color is L. pneumophila known for?
Autofluorescence: yellow-green
what are the two main clinical manifestations of infection with Legionella
febrile disease with pneumonia aka Legionarrie’s disease, and febrile disease without pulmonary involvement aka Pontiac fever.
what are the two major media types useful for isolating Bordetella and what is the transport medium? what is common between?
Bordet-Gengou (potato infusion with glycerol and horse or sheep blood), and charcoal with horse blood and 40 mg/L cephalexin; Regan Lowe is like the charcoal media but with full agar strength.
*some B. pertussis strains are inhibited by this level of cephalexin so there should be a plate without it also cultured.
How do colonies of Bordetella pertussis and parapertussis appear on Regan-Lowe or charcoal-horse blood, and on Bordet-gengou?
as smooth shiny mercury-droplet like on charcoal; As hemolytic on the potato agar
