Bacteriology morphology & agars Flashcards
Gram negative straight barrel shaped rods
Enterobactericeae
Gram + lancet shaped diplococci
Strep pneumo
Gram - kidney shaped diplococci
Neisseria
Gram + thick spore forming bacilli
Bacillus, Clostridia
Gram + small bacilli
Listeria
Gram +small bacilli in Chinese letters
Corynebacteria & Proprionibacteria (diptheroids)
Gram - curved rods
Vibrio
Gram - curved, S or corkscrew shaped rods, look like seagulls
Campylobacter
Gram - rods with safety pin appearance
Yersina pestis
Gram - coccobacilli in tissue
Legionella
Gram - highly pleomorphic bacilli when grown on BCYE: lollipop, dumbbell and teardrop shapes
Cardiobacterium hominis
Gram + branching, filamentous bacilli
Nocardia & Actinomyces
How often should blood cx’s be taken in suspected bacteremia? How much blood should be put in each bottle?
3 sets of 2 in a 24 hr pd, at least 30 minutes apart; >10mL
What are the steps for gram stain technique
Crystal violet, Gram iodine, Decolorize, Safranin, rinse
What dye is used in the acid fast stain and what does it bind to?
carbol fuscin, mycolic acid
How is the Kinyoun technique different from the Ziehl-Neelsen? Fite?
The kinyoun is a cold technique while Ziehl is a hot technique using a stronger 3% HCl; In Fite a weaker 1% H2SO4 is used **Nocardia and M leprae may be acid-fast with Fite and not Ziehl
What are the AFB organisms?
Mycobacteria, Nocardia, Cryptosporidium, Microsporidium, Isospora, Sacrocystis, Legionella micdadei, Rhodococcus equi, Saccharomyces
Campy-BAP
selects for Campylobacter
Buffered charcoal yeast extract (BCYE)
Legionella; agar with antibiotics will inhibit most other upper respiratory flora and leave Legionella growing
Thayer-Martin agar
Neisseria spp
MacConkey agar
Selects for gram negative bacteria (bile salts) and differentiates between fermenting/non with lactose
Red colonies on MacConkey
Escherichia, Klebsiella, Enterobacter (strong lactose fermenters)
Pink colonies on MacConkey
Citrobacter, Providencia, Serratia, Hafnia
Colorless colonies on MacConkey
Proteus, Edswardsiella, Salmonella, Shigella
Eosin methylene blue agar (EMB)
selects for gram negative bacteria (aniline dye) and differential media
Green-black-purple on EMB agar
Escherichia, Klebsiella, Enterobacter, Serratia, Hafnia, Citrobacter, Providencia
Colorless colonies on EMB agar
Proteus, Edwardsiella, Salmonella, Shigella
Salmonella-Shigella agar
Inhibits growth of most coliforms (bile sals and sodium citrate) and has lactose
Colorless colonies on S-S agar
Shigella
Colorless colonies with black center on S-S agar
Salmonella
Hektoen-enteric agar (HE)
same purpose as S-S agar
Salmon-pink to orange colonies on HE agar
fermenters (E.coli)
Green colonies on HE agar
Shigella
Green colonies with black center on HE agar
Salmonella
Mannitol salt agar (MSA)
inhibits most gram-negative organisms. Can be used to isolate Staph aureus from mixed cultures
At what temperature is Listeria most motile? Is that the only temperature it grows at?
tumbling motility only at 25 degrees C
Can also grow at 37 degrees C
What two species grow at 25 to 30 degrees C?
Pseudomonas fluorescens and Mycobacterium marinum
What is the optimal temperature for initial plating of most organisms?
37 degrees C
