Bacteriology - MICRO LAB Flashcards
Way differentiate gram-positive cocci Staph versus strep?
Staph is catalase +
Strep is Catalase (-)
Way to differentiate Step epidermidis from saprophyticus?
Novobicin test.
saprophyticus is resistant to novobicin.
What are the 2 beta hemolytic strep?
Strep pyogens [GAS]
S. agalactiae [GBS]
How are GAS and GBS differentiated?
GAS: Bacitracin sensitive
GBS: Resistant
What list the GPC, catalase negative, alpha and gamma hemolytic [4]
- S. pneumo
- Viridans group strep
- Enterococcus
- S. bovis
What is the purpose of the optochin test?
Catalase negative alpha/gamma GPC:
–> Strep pneumo is sensitive to optochin and will be killed, removing it as a possibility
What is the purpose of the bile esculin test?
Catalase negative alpha/gamma GPC:
–> Only GDS and Enterococcus are positive, excludes viridans strep and strep pneumo.
What is the point of the 6.5% NaCl growth test?
Catalase negative alpha/gamma, bile esculin + GPC:
–> Only Enterococcus species can grow, inhibits strep bovis [GDS]
What is the purpose of the tellurite test?
Catalase negative alpha/gamma, bile esculin +, 6.5% NaCl growth test + GPC:
–> Differentiates E. faecalis from E. faecium.
E. faecalis reduces tellurite to tellium, turing the media black.
E. faecium does not.
Three medically important gram negative cocci?
- Moraxella catarrhalis
- N. gonorrhoeae
- N. meningitidis
What does M. catarrhalis ferment?
Nothing
What does N. gonorrhoeae ferment?
Glucose
What does N. meningitidis ferment?
Maltose and glucose
Which GNDC can reduce nitrates?
M. catarrhalis
Which GNDC is oxidase +?
ALL 3
–> Positive means cytochrome c is present
Which GPR are spore forming? [3]
Clostridium
B. cereus
B. anthacis
How is bacillus separated from clostridium species?
Bacillus is aerobic
Clostridium is anaerobic
How is B. anthacis separated from B. cereus? [3]
GBR, spore forming, aerobic
- -> B. anthacis is penicillin sensitive, B. cereus is NOT.
- -> B. cereus is MOTILE, anthacis is not
- -> B. cereus is beta hemolytic, anthracis is not
What are the non-spore forming GPR?
A. haemolyticum Corynebacterium E. rhusiopathiae G. vaginalis Lactobacillus Listeria Nocardia
Which GPR are beta hemolytic? [3]
A. haemolyticum
B. cereus
L. monocytogenes
Which GPR are catalase positive? [3]
Bacillus
C. diphtheriae
L. monocytogenes
Which GPR are catalase negative [3]
A. haemolyticum
Erysipelothrix
Lactobacillus
How should C. diphtheriae be evaluated? Morphology on gram stain? Spore forming? Motility? Medium to enhance growth? [2] Special features on stain?
GPR
+ Catalase
NON-SPORE forming
NON-Motile
–> Loffler’s medium inhibits other throat flora and enhances typical metachromasia [methylene blue stain will highlight this
–> Tellurite plate highlights reduction of tellurium salt
Gram stain shows GPR with large boxcar appearance. +/- spores. Ddx?
- Clostridium
- Bacillus
GPR with small palisading arrangement on gram stain. Ddx? [3]
Corynebacterium species
Arcanobacterium hemolyticum
Listeria monocytogenes
What is a clostidium species that will stain GRAM NEGATIVE ROD?
Clostridium tertium
What are the biochemical characteristics of ALL GRN that are enterobacteriaceae?
- -> Catalase?
- -> Oxidase?
- -> Nitrate reduction?
- -> Glucose fermentation?
- Catalase +
- Oxidase -
- Nitrate reducers
- Glucose fermenters
List all enterobacteriaceae [13]
- Escherichia
- Klebsiella
- Hafnia
- Proteus
- Salmonella
- Serratia
- Shigella
- Yersinia
- Providencia
- Enterobacter
- Morganella
- Citrobacter
- Edwardsiella
List the GRN that are NOT enterobacteriaceae that ferment lactose. [4]
- Aeromonas
- Pasteurella
- Plesiomonas
- Vibrio
List the GRN that are NOT enterobacteriaceae that do NOT ferment glucose. [6]
Acinetobacter Alcaligenes Burkholderia Flavobacterium Pseudomonas Stenotrophomonas
List the GRN that are NOT enterobacteriaceae that do DO ferment glucose. [4]
Aeromonas
Pasteurella
Plesiomonas
Vibrio
Which GRN produce H2S? [4]
Citrobacter freundii
Edwardsiella tarda
Proteus [both vulgaris and mirabelis]
Salmonella
Which GRN ferment lactose? [5]
E. coli Enterobacter aerogens, cloacae Citrobacter [50%] Vibrio vulnificus Klebsiella pneumoniae
Which GRN are oxidase positive? [12]
NOTE: NO enterobacteraciae are oxidase positive. Aeromonas Plesiomonas Pseudomonas Alcaligenes Burkholderia Campylobavter jejuni Flaobacterium H. pylori Kingella Pasteurella Vibrio cholerae, parahaemolyticus
Which GRN that are NON-enterobacteraciae are oxidase negative?
NOTE: ALL enterobacteraciae are oxidase negative.
Acinetobacter
Klebsiella pneumonia
Stenotrophomonas
Which enterobacteraciae are indole positive? [4]
E. coli
P. vulgaris
Providencia
Morganella
Which non-enterobacteraciae are indole positive? [5]
K. oxytoca Vibrio Aeromonas Plesiomonas Pasteurella
Which enterobacteraciae are indole negative? [4]
Salmonella
Enterobacter
Serratia
P. mirabilis
Which non-enterobacteraciae are indole negative?
Klebsiella
Pseudmonas
What culture media is used for pertussis?
Bordet-Gengou [previous]
Regan-Lowe [current]
Describe stenotrophomonas resistance pattern
Resistant to the following routinely…
- Pencillins
- Cephalosporins
- Aminoglycosides
- Carbapenems
Treatment of choice for steno?
Bactrim
