Final Exam Flashcards
Bacterial capsules are associated with what property?
virulence
What phase of the bacterial growth curve is best for biochemical testing?
log phase
What type of environment is provided by the candle jar?
microaerophilic
What is the purpose of Albert’s stain?
simple stain to stain the metachromatic granules of Corynebacterium diptheriae; used to identify the cause of diphtheria
What is an example of differential media?
MacConkey
What is an example of enriched media?
chocolate agar, blood
What is an example of selective media?
MacConkey, Thayer Martin, and CNA
What are the standard conditions for the autoclave?
121ºC at 15 psi for 15 minutes
What is the most abundant organism found in the human intestinal tract?
Bacteroides
What is the most important single test that differentiates Staphylococcus aureus from non-pathogenic staphylococci?
coag
α Streptococcus viridans are the most important cause of what serious illness?
subacute bacterial endocarditis
What is the ONLY significant pathogen in a throat culture?
Group A β Strep
Enterococcus belongs to what Lancefield group?
Group D
Enterococcus results on BEA and 6.5% NaCl
+ +
Foul smelling pus from an abscess which yields gram positive cocci in chains on gram stain would be indicative of what organism?
Anaerobic strep
How do you identify Neisseria gonorrhaeae?
Oxidase + Gram = diplococci growing on Thayer Martin agar, only dextrose +
What are the identifying characteristics of Neisseria meningitidis?
Gram = coffe bean shaped diplococci, dextrose +, maltose +, oxidase +
What three antibiotics are added to Thayer-Martin to make it a selective medium for pathogenic Neisseria?
Vancomycin, colistin, nystatin
What are the general characteristics of the family Enterobacteriaceae?
all glucose fermenters, oxidase =, nitrate +, peritrichous if motile +
What is the appearance of a positive test for citrate?
growth and/or blue
What is the appearance of a positive test for indole?
red layer with addition of Kovac’s reagent
What is the appearance of a positive test for H2S?
black growth on medium
What is the appearance of a positive test for phenylalanine?
green to blue color with addition of ferric chloride
What is the appearance of a positive test for VP?
red
What are the reagents used for the indole test?
Kovac’s reagent
What are the reagents used for the nitrate test?
sulfanilic acid
What are the reagents used for the phenylalanine test?
ferric chloride
What are the reagents used for the VP test?
alpha napthal/potassium hydroxide
What are the characteristics of E. coli?
Gram =, TSI A/A, Indole +, Citrate =, Lysine +, Ornithine +, Urea =, Motile +
What is the best means to differentiate the genus Enterobacter from the genus Klebsiella?
motility, Klebsiella is nonmotile
Which genera are urea positive?
Klebsiella, Proteus
LDC differentiates what organism from non-pathogenic H2S producers such as Citrobacter and Proteus?
Salmonella
What is the causative agent of hemorrhagic colitis and hemolytic uremic syndrome due to is production of Verotoxin?
E. coli 0157
What is Verotoxin also known as?
Shiga-like toxin
What are the characteristics of Serratia marcesens?
chromogenic, resistant to antibiotics, associated with UTI, hospital-acquired infections, and wound infections in people who s pend a lot of time outdoors in the woods
What test differentiates Proteus mirabilis from Proteus vulgaris?
Indole, mirabilis is indole =
Which genera are phenylalanine positive?
Proteus, Providencia, and Morganella
Which organisms causes an infection of the mesentery suggestive of acute appendicitis?
Yersinia pseudotuberculosis
K/A with gas and H2S in TSI is suggestive of what intestinal pathogen?
Salmonella
What non-pathogenic organism is biochemically so similar to Shigella that isolates that are biochemically identified as Shigella must be typed?
Alkalescens dispar
What is the difference between a food poisoning and a food infection?
Food poisoning is rapid from an enterotoxin; food infection is from ingesting large amounts of viable organisms and takes 18-24 hours
What organism could be described as an oxidase positive, glucose-fermenting rod commonly found in water and soil?
Aeromonas hydrophilia
A Gram negative coccobacillus isolated from a cat bite is most likely to be?
Pasteurella multocida
A salt-loving organism responsible for gastroenteritis due to contaminated sea food is most likely to be?
Vibrio parahemolyticus
What media is used to differentiate between oxidation and fermentation?
Hugh and Leifson green semisolid
A Gram negative coccobacillus isolated from a patient with endocarditis that is oxidase +, catalase -, indole +, non-motile and weakly fermentative would most likely be?
Cardiobacterium hominus
What are the three most commonly isolated non-fermentative bacteria?
Pseudomonas aeruginosa, Acinetobacter, Stenotrophomonas maltophilia
A non-fermenter with a blue-green pigment and a grape-like odor is what?
Pseudomonas aeruginosa
A non-fermentor that is a strong maltose oxidizer and a weak glucose oxidizer is?
Stenotrophomonas (Xanthomonas) maltophilia
What is the causative agent of glanders?
Burholederia mallei (Pseudomonas)
A Gram negative, oxidase negative coccobacillus is?
Acinetobacter
What genus of bacteria can be confused with Neisseria because they are oxidase + and sometimes grow on Thayer-Martin and can be differentiated by gram stain since those organisms are Gram negative rods rather than cocci?
Morexella