mirco exam 1

What is another name for Rothia mucilaginosus (Stomatococcus)?

"Sticky Staph"

Which chemical agent is recommended for blood spills?

1/10 dilution of bleach (NaClO)

clean 1st (soap & water) & then disinfect

Agar media melts at \_________ and stays liquid until 45-50o C (or solidifies at 45-50o C).

100 degrees C

What is the appropriate temperature and pressure when autoclaving material?

15 psi for 121 C degrees for 15 minutes

What is the optimal incubation temperature for most bacteria?

35 to 37 degrees C (body temperature)

What are the three most common temperatures used in the laboratory to isolate bacteria?

35-37 degrees,22-25 degrees (room temperature)& 42 degrees

What reagent is used for the hippurate test if sodium benzoate is detected?

7% Ferric chloride

What the genus names for satelliting strep?

Abiotrophia & Granulicatella

An animal infectious disease transmitted to humans is referred to as zoonosis. Which zoonotic organisms have we studied?

Bacillus anthracis, Erysipelothrix, & Listeria (when due to food poisioning)

Gram-positive, large rods
Spores present
Nonhemolytic
Nonmotile
Catalase \= positive
What is the identification?

Bacillus anthracis

Which Gram-positive rods are associated with food poisoning?

Bacillus cereus and Listeria

Name an aerobic, spore-forming genus

Bacillus species

Gram-positive, large rods
Spores present
Hemolytic
Motile
Catalase \= positive
What is the identification?

Bacillus species

Motility \= negative
Catalase \= positive
Hemolysis \= usually gamma
Gram stain \= "Chinese letters"
What is the identification?

Corynebacterium species

PYR \= Positive
Alpha/gamma hemolytic
What is the identification ?

Enterococcus species

Name two organisms (GPC) that are more resistant to antibiotic treatment.

Enterococcus & satelliting streptococcus

Bile-esculin \= Black
6.5% salt \= Growth
P disk \= R
What is the identification ?

Enterococcus species

Which Gram-positive rod produces H2S?

Erysipelothrix

Motility \= negative
Catalase \= negative
Hemolysis \= alpha/gamma
Gram stain \= Gram-positive rods
H2S production on TSI
What is the identification?

Erysipelothrix

Motility \= negative
Catalase \= negative
Hemolysis \= alpha/gamma
Gram stain \= chains of Gram-positive rods
What is the identification?

Lactobacillus

Motility \= negative at 35 & positive at 25
Catalase \= positive
Hemolysis \= beta
Bile-esculin \= Black
Gram stain \= Small, Gram-positive coccobacillary
What is the identification?

Listeria monocytogenes

Which organism produces tumbling motility in wet mounts?

Listeria monocytogenes

Which organism produces umbrella-like growth pattern in semisolid agar?

Listeria monocytogenes

Bacitracin \= S
Furazolidone \= R
Modified oxidase \= Blue
Catalase \= Bubbles
These test results identify the MO as:

Micrococcus

Which streptococcus-like bacteria are vancomycin resistant?

Pediococcus & Leuconostoc

Bacitracin \= R
Furazolidone \= S
Modified oxidase \= Colorless
Catalase \= No bubbles
These test results identify the MO as:

Rothia mucilaginosus (Stomatococcus)

Tube coagulase positive
What is the identification ?

Staphylococcus aureus

Slide coagulase result:
saline \= no clumps
plasma \= clumps
What is the identification?

Staphylococcus aureus

A disk \= R
CAMP \= Arrowhead hemolysis
PYR \= No color change
SXT \= R
What is the identification ?

Streptococcus agalactiae

Bile-esculin \= No color change
6.5% salt \= No growth
P disk \= S
What is the identification ?

Streptococcus pneumoniae

Bile soluble \= clearing of MO
What is the identification ?

Streptococcus pneumoniae

A disk \= S
CAMP \= negative
PYR \= positive
SXT \= R
What is the identification ?

Streptococcus pyogenes

A physician sends a throat swab to the laboratory, requesting antigen testing for Group A streptococcus. What are the correct responses to positive antigen test results and negative test results?

* result is reported as Group A strep= result is confirmed with culture

A physician sends a throat swab to the laboratory, requesting culture and Gram stain for Group A streptococcus. Is the Gram stain request appropriate for GAS?

No,many types of normal flora streptococcus (not GAS) are present

What tests are appropriate for beta-hemolytic, catalase negative, GPC organisms?

A & SXT disks,PYR,CAMP or hippurate hydrolysis & Serogrouping

Facultative anaerobes can live \_________________ & \_______________.
Examples are \___________ & \___________.

Aerobically & anaerobically
Staphylococcus & Streptococcus

What type of hemolysis has a zone of greenish discoloration?

Alpha

What type of hemolysis is exhibited by Lactobacillus & Erysipelothrix?

Alpha and Gamma

What type of hemolysis is demonstrated by Streptococcus pneumoniae, viridans streptococcus, Enterococcus species, & nonenterococcal Group D streptococcus?

Alpha hemolysis

Which organism is described as producing Medusa head growth on media and "string of pearls" appearance on Gram stain?

Bacillus anthracis

What reagent is in the A disk?

Bacitracin

What media are used to isolate Corynebacterium diphtheriae?

BAP, cystine-tellurite OR Tinsdale, and Loeffler OR Pai

What type of hemolysis involves the complete lysis of RBCs?

Beta \= clear zone underneath colony

What type of hemolysis is demonstrated by Groups A, B, C, F, & G Streptococcus?

Beta

What type of hemolysis is exhibited by Arcanobacterium haemolyticum?

Beta

What type of hemolysis is exhibited by Listeria monocytogenes?

Beta

How are Listeria and Group B Streptococcus similar?

Beta hemolytic, + for hippurate & CAMP & cause meningitis/bacteremia in babies

Which organism is used to perform the CAMP test?

beta-lysin producing S. aureus- (not all S. aureus produce beta-lysin)

What reagent is used for the bile solubility test?

Bile salts (sodium deoxycholate)

Name two examples of nonselective media.

Blood agar & chocolate agar

Underdecolorized WBCs will appear \__________.

Blue-purple

Slide coagulase test detects \__________________ .

Bound coagulase (clumping factor)

The staphylococcus latex aggulutination test detects \________ & \_________. In addition some tests detect capsular polysaccharides.

Bound coagulase (clumping factor) & protein A

How are CO2 levels checked in CO2 incubators?

By using a fyrite measuring device

What tests are appropriate for gamma-hemolytic, catalase negative, GPC organisms?

CAMP or hippurate hydrolysis, Bile-esculin, 6.5% salt & PYR

Which media should always be QC'ed by the laboratory?

Chocolate agar, selective media for pathogenic Neisseria, & Campylobacter agar

Capnophilic organisms require an increased amount of \_____________ and an example of a capnophilic organism is \___________ \_____________.

CO2,Neisseria gonorrhoeae

What is the primary disease caused by Streptococcus pneumoniae?

Community acquired pneumonia

Which organisms are referred to as having diphtheroid or coryneform morphology?

Corynebacterium, Arcanobacterium, & Rothia

List the Gram stain reagents in the correct order for test performance.

Crystal violet, Gram's iodine, Decolorization, & Safranin

How often should personnel check tempertures on laboratory incubators?

Daily

Which test is used to determines C. diphtheriae toxin formers?

Elek test

Which toxin is found in the cell wall of Gram-negative organisms?

Endotoxin,found in lipopolysaccharide part of cell wall

Which toxin is produced by living bacteria and secreted into the surrending medium?

Exotoxin

Tube coagulase test detects \__________________ .

Extracellular coagulase

Why is methylene blue stain used for detection of Corynebacterium diphtheriae?

For ID purposes - reveals metachromatic granules

What type of hemolysis is demonstrated by Group B Streptococcus, viridans streptococcus, Enterococcus species and nonenterococcal Group D streptococcus?

Gamma hemolysis

What type of hemolysis is exhibited by Bacillus anthracis?

Gamma hemolysis

What type of hemolysis is exhibited by Corynebacterium species?

Gamma hemolysis

What type of hemolysis is considered no hemolysis (nonhemolytic)?

Gamma hemolysis

Name four examples of enrichment broths and describe their uses.

GN & Selenite \= isolation Salmonella & Shigella
LIM & Trans-Vag \= isolation GBS

A disk \= S
CAMP \= No arrowhead hemolysis
PYR \= Red
SXT \= R
What is the identification ?

Group A Streptococcus

What does Staphylococcus look like on Gram stain?

Gram-positive cocci in clumps (clusters)

What does Streptococcus pneumoniae look like on Gram stain?

Gram-positive cocci in pairs (lancet shaped)

What does Micrococcus look like on Gram stain?

Gram-positive cocci in tetreds

How does Corynebacterium species appear on Gram stain?

Gram-positive, small pleomorphic rods ("Chinese" letters)

What is the Gram-stain result for Listeria?

Gram-positive, small rods (may be coccobacillary)

PYR \= Red
Beta hemolytic
What is the identification ?

Group A Streptococcus

A disk \= R
Hippurate \= Positive
PYR \= Negative
SXT \= R
What is the identification ?

Group B Streptococcus

What reagent is used for the catalase test?

H2O2

Humidophilic organisms require increased \___________ and an example of a humidophilic organism is \_____________ \_____________.

Humidity,Haemophilus ducreyi

What is the purpose of the Quellung reaction?

Identify Streptococcus pneumoniae - specific capsular antigens

Which media is not QC'ed as long as the manufacturer sents documentation of successful quality control testing?

MAC, EMB, CNA, PEA, & BAP

What reagent is used for the PYR test?

N, N-dimethylaminocinnamaldehyde

What reagent is used for the hippurate test if glycine is detected?

Ninhydrin

Bile-esculin \= Positive
6.5% salt \= No growth
Optochin \= R
What is the identification ?

Non-Enterococcus, Group D Streptococcus

What test is performed only on Staphylococcus coagulase-negative isolates from urine cultures?

Novobiocin susceptibility

Name two examples of nutrient media.

Nutrient agar & trypticase soy broth

What reagent is in the P disk?

Optochin (also called ethylhydrocupreine hydrochloride)

Microaerobic organisms require a decreased amount of \___________ and an example of a microaerobic organism is \_______________.

Oxygen,Campylobacter

An anaerobic atmosphere is without \__________ and an example of an anaerobic organism is \______________.

Oxygen,Clostridium

What tests are appropriate for alpha-hemolytic, catalase negative, GPC organisms?

P disk or bile solubility, Bile-esculin, 6.5% salt, & PYR

Slide coagulase results:
saline \= clumps
plasma \= clumps
What should be the next step?

Perform tube coagulase due to autoagglutination

Overdecolorized Gram positive bacteria will appear \___________.

Pink to red

What reagent is used for the coagulase test?

Plasma

Slide coagulase negative
What is the identification?

Probably Coagulase Negative Staph - confirmed w/ tube or latex agglutination

What is satelliting streptococci deficient in?

pyridoxal (vitamin B6)

Appearance of Staphylococcus coagulase negative & Micrococcus on MSA agar (MOs don't ferment mannitol)

red colonies

What organism is referred to as nutritionally deficient, thimol requiring, nutritionally variant, pyridoxal dependent, symbiotic streptococcus, & vitamin B6 dependent?

Satelliting streptococci