MICROBIO LAB FINAL EXAM

practice questions

Based on the growth pattern within the tube, what type of anaerobic tolerance is this microorganism?

A facultative anaerobe (example: E. coli)

Based on the growth pattern within the tube, what type of anaerobic tolerance is this microorganism?

A microaerophile (example: Microccous luteus)

Based on the growth pattern within the tube, what type of anaerobic tolerance is this microorganism?

An anaerobe (example: Clostridium butyricum)

In regards to the Anaerobic jar, what happens to the strip of methylene blue when oxygen is reduced within the jar?

The strip of methylene blue becomes colorless

What type of hemolysis means the complete destruction of RBC’s (red blood cells) and appears transparent? (example: Streptococcus pyogenes)

β Beta-hemolysis

What type of hemolysis means the partial destruction of RBC’s (red blood cells) and appears translucent? (example: Streptococcus pneumoniae)

α Alpha-hemolysis

What type of hemolysis means no destruction of RBC’s (red blood cells)? (example: Staphylococcus epidermidis)

γ Gamma-hemolysis

This microorganism appears green on EMB plates and pink/orange on HE plates making it a lactose fermenter, which microorganism is it?

E. coli

This microorganism appears pink on EMB plates and pink/orange on HE plates making it a lactose fermenter, which organism is it?

Enterobacter

There are 2 microorganisms that show no color on EMB plates making them lactose non-fermenters. They also form black precipitate on HE plates due to H2S production, which 2 microorganisms are these?

Proteus and Salmonella

What does H2S stand for?

Hydrogen sulfide

This microorganism has no color on EMB plates making it a lactose non-fermenter, but it does appear blue-green on HE plates. Which microorganism is it?

Shigella

What is the primary selective and differential medium (plate) used to distinguish between Staphylococcus aureus and Staphylococcus epidermidis?

Mannitol Salt Agar (MSA) plate

This microorganism appears as yellow on MSA plates due to fermentation of mannitol and causes beta hemolysis on blood agar plates, which microorganism is it?

Staphylococcus aureus

This organism appears as pink on MSA plates because it does not ferment mannitol and causes gamma hemolysis on blood agar plates, which microorganism is it?

Staphylococcus epidermidis

What percentage of sodium chloride (NaCl) is on MSA plates?

7.5% NaCl

What is the catalase test used to differentiate?

It is primarily used to differentiate Staphylococcus (positive, bubbles) from Streptococcus (negative, no bubbles)

Which microorganism causes complete beta hemolysis on blood agar plates and is sensitive to bacitracin (A disk)?

Streptococcus pyogenes

Which microorganism causes partial alpha hemolysis on blood agar plates with a greenish color and is sensitive to Optichin (P disc)?

Streptococcus pneumoniae

What diseases are causes by Staphylococcus aureus?

Impetigo, cellulitis, abscess, boils, furuncle, food poisoning, Toxic Shock Syndrome, septicemia

Which diseases are caused by the Streptococcus species?

Sepsis, scarlet fever, Rheumatic Fever, Necrotizing Fasciitis, Toxic Shock Syndrome, septicemia, nephritis

The indirect ELISA test detects ______ in a patient's blood.

antibodies

Which test is done to confirm a positive ELISA test?

Western Blot test

What is the most common method to collect urine specimen?

Clean catch method

Which of the following methods is used to collect sterile urine specimen?

Catheterization

How do you distinguish between Streptococcus pyogenes and Streptococcus pneumonia?

Streak for isolation and add Bacitracin (A) and Optochin (P) disks

What would be the next step in Identification of the bacterium growing on this plate?

Catalase test

Selective and differential agars used in clinical setting to:

Separate possible pathogen from normal flora

Which media are used for identification of bacteria causing gastrointestinal symptoms?

EMB and HE

Which bacteria are identified by EMB plate?

E.coli and Enterobacter

What is the Gram reaction and microscopic morphology of an organism growing on this HE plate?

Gram (-) bacillus

Which disinfectant is the most effective on this plate? Name quadrant

1.

An organism growing on this urine plate is:

Gram (-) bacterium

Which of these plates will test positive for Catalase test?

A.

Which of the types of media are used to diagnose UTI?

EMB, Blood agar, SAB

Mannitol salt agar is selective for which bacterial genus?

Staphylococcus

What is an indication of a positive Catalase test?

Bubbles

Manitol Salt agar is classified as:

Selective and Differential medium

A patient has a suspicious skin infection and a culture is taken. Which media would be appropriate to select for staphylococci? 

Mannitol salt agar

Enterotube is used to distinguish between:

Proteus and Salmonella

The more sensitive bacteria to the drug, the bigger a zone of inhibition will be, True or False?

True