B7 Infectious diseases Objectives

Question 1

Developed countries: whats the leading cause of death?

Developing countries: whats the leading cause of death?

Answer 1

Coronary Heart Disease (CHD)

Lower respiratory infection (LRI)

Question 2

1 infectious disease related cause of blindness

Answer 2

Trachoma! (Likely Question)

Question 3

What causes trachoma?

Answer 3

Chlamydia (both are intracellular)

Question 4

Types of microorganisms identified by:
KOH preparation
Calcoflour white preparation
Gram stain
Ziehl-Neelsen stain
Inclusion bodies in epithelial cells of the conjunctiva and interpret a Wright Giemsa stain to determine if epithelial inclusion bodies are present.

Answer 4

KOH: Fungi and Fungal Hyphae
CFW: Fungi and Fungal Hyphae but with Fluorescence
Gram stain: Bacteria
Acid Fast (ziehl Neelsen): Mycobacterium/TB and others (ACID COMIN FAST ATCHEW I MIGHT GO BACK TO THE BUS)
WG: blood smear for white blood cells
-epithelial inclusion bodies, protozoans
-Lighter colored fried egg looking stain is an inclusion body (have brown nuclei if Iodine)

Question 5

Thick peptidoglycan is what gram stain?

Answer 5

Gram Positive stain

Question 6

Thin peptidoglycan is what gram stain?

Answer 6

Gram Negative stain

Question 7

Gram stain steps

Answer 7

Heat fixation
Crystal Violet
Iodine treatment
Decolarization (alcohol)
Counter stain (saffranin)

Diplococcus- pairs
Streptococcus- "strip"tococcus (chains)
Staphylococcus- clusters
Vibrio- comma shaped
Spirochetes- thin walled helical w/o flagella (can't be seen on gram stain!)

Question 8

Acid fast stain flood with what?

Answer 8

Carbolfuschin (RED IS POSITIVE)

Question 9

Why do you use acid-alcohol as a decolarizer?

Answer 9

Need very rough acid to damage cell wall of all bacteria except the acid fast bacterial cell wall

Question 10

Predict classes of microorgansisms in each:
Blood agar
Chocolate Agar
Thayer-Martin Agar
MacConkey's Agar
Mannitol Salt Agar
Lowenstein Jensen Agar
Sabouraud Dextrose Agar

Answer 10

BA: Most Bacteria (general and differential)
Chocolate: Fastidious bacteria (haemophilus, Neisseria)
Thayer-Martin: Neisseria
MacConkey’s: Gram negative rods
Mannitol salt: Staphylococci
Lowenstein Jensen Agar: Mycobacterioum ssp

Question 11

Blood agar

Answer 11

Blood Agar: Most Bacteria (general and differential)

BA because it is for most bacteria

Question 12

Chocolate Agar

Answer 12

Chocolate: Fastidious bacteria

fastidious means complex nutritional requirement… of chocolate

Question 13

Thayer-Martin Agar

Answer 13

Thayer-Martin: Neisseria (Dr. Martin Driving a Nissan from nigeria= Neisseria)

Question 14

MacConkey’s Agar

Answer 14

MacConkey’s: Gram negative rods (MacConkin you on the head with big gram negative rods)

Question 15

Mannitol salt Agar

Answer 15

Mannitol salt: Staphylococci (Man with salt holding a staph)

Question 16

Lowenstein Jensen Agar

Answer 16

Lowenstein Jensen Agar: Mycobacterium

Lowenstein and Jensen broke up but Jensen Myco back to em

Question 17

Sabouraud Dextrose Aga

Answer 17

Fungi (low pH and gentamicin)

Remember Sabouraud, hes a fun guy

Question 18

Why do you not use Ethanol with a blood culture from the conjunctiva?

Answer 18

Coagulase negative staphlococcus