Exam 1: Intro to ID Flashcards
(123 cards)
Which bacteria retain crystal violet and iodine (stain purple): Gram + or Gram -?
Gram +
*note that Gram - bacteria are counterstained with safranin dye and appear pink/red
How does the Gram + bacteria’s peptidoglycan cell wall vary from Gram - bacteria?
Gram + bacteria: Have a thick peptidoglycan cell wall which is why they retain crystal violet
Gram - bacteria: Have a thin peptidoglycan cell wall
What are atypical bacteria?
Bacteria that do not stain using a Gram-stain
What are Acid-Fast Bacilli (AFB)?
Bacteria resistant to decolorization procedures by acids/ethanol
What is an example of an Acid-Fast Bacilli (AFB)?
Mycobacterium species
Most medically important Gram + pathogens are what type?
Cocci
(most bacilli are contaminants/ normal flora)
Which cocci species form clusters?
Staphylococcus
Which cocci species form pairs/chains?
Streptococci
Enterococci
The catalase test is used to differentiate between which two species?
-Staphylococci
-Streptococci
The coagulase test is used to differentiate between which two species?
-Staphylococcus aureus
-Coagulase-negative staphylococcus (CoNS)
alpha-hemolytic bacteria appear in which part of the body?
Oral flora
beta-hemolytic bacteria appear in which part of the body?
Skin, Pharynx, Genitourinary
gamma-hemolytic bacteria appear in which part of the body?
Gastrointestinal
What are the HACEK organisms?
-Haemophilus
-Actinobacillus
-Cardiobacterium
-Elkenella
-Kingella
Most Gram (-) pathogens are what?
Bacilli
Lactose fermentation is used to identify which two Gram (-) groups?
-Enterobacterales (enteric gram-negative rods or lactose fermenting gram-negative rods)
-Non-fermenting gram-negative rods
The oxidase test is used to distinguish which two Gram (-) groups?
Enteric lactose fermenters
Non-enteric lactose fermenters
What are fastidious organisms?
Slow growers
-require special supplement media
Review:
Lecture 2 Slide 18 for normal flora
What are Penicillin-Binding Proteins (PBP’s)?
Enzymes vital for cell wall synthesis, cell shape, and structural integrity
*beta lactams bind here
*largest drug target
What are 3 examples of Penicillin-Binding Proteins (PBP’s)?
Transpeptidases
Carboxypeptidases
Endopeptidases
Binding to which segments of Penicillin-Binding Proteins (PBPs) result in a bactericidal effect?
1A
1B
2
3
What is the specific job of the most important Penicillin-Binding Proteins: Transpeptidases?
Catalyze the final cross linking in the peptidoglycan structure
What is the cytoplasmic membrane?
Acts as a selective barrier
-certain drugs must pass through to reach their target site