Microbial structure and classification Flashcards
What cell wall component is unique to Fungi?
Chitin
Bacteria that stain blue/purple are likely to be what type of bacteria and why?
Gram Positive cocci or rods
Low lipid composition
Bacteria that stain red are likely to be what type of bacteria and why?
Gram Negative cocci or rods
High lipid composition
What is cell wall in gram positive bacteria made up of?
Thick peptidoglycan layer made up of repeating units of NAM-peptide and NAG, as well as Lipoteichoic acid and Teichoic acid
Inner cytoplasmic membrane phospholipid bilayer
ZN stain is used for what bacteria and why?
Mycobacterium Tuberculosis - The waxy mycolic acid of acid-fast bacilli
What is the cell wall in gram negative bacteria made up of?
Outer membrane phospholipid bilayer which contains LPS, Porins
Thin Peptidoglycan layer made up of repeating units of NAM-peptide and NAG
Inner cytoplasmic membrane phospholipid bilayer
Which type of bacteria (G +ve or G -ve) contains spore-formers?
Gram Positive
Which type of bacteria (G +ve or G -ve) are resistant to desiccation?
Gram Positive
Which type of bacteria (G +ve or G -ve) produce exotoxins?
Gram Positive
Which type of bacteria (G +ve or G -ve) have endotoxin within their cell wall?
Gram Negative
True or False: Gram Negative bacteria do not survive drying.
True
What is the main difference between endotoxins and exotoxins?
Exotoxins are highly specific to a particular substrate.
Name 2 diagnostic techniques used to identify a viral infection using a patient’s serum?
- ELISA -Detects the presence of antibodies or antigens in the blood serum.
- PCR of serum - Detects Viral RNA and DNA.
How are Gram Positive Cocci classified?
- Staphylococci - form clusters in culture
Coagulase test is used to differentiate between different Staphylococci - Staph aureus is coagulase positive
Coagulase negative staphylococci are generally opportunistic pathogens
- Streptococci - form pairs and chains in culture
Their effect on blood cells is what is used to differentiate between different Streptococci.
Beta-haemolytic streps cause complete lysis of RBCs - Streps A, B, C
Alpha-haemolytic streps cause incomplete lysis of RBCs - Strep pneumoniae
Non haemolytic streps do not cause lysis of RBCs
- Enterococci, anaerobes
What function of gram positive bacteria can be used to differentiate between different gram positive rods?
Whether or not they produce spores
Form spores - Anthrax, Tetanus, Botulism
Do not form spores - C. diphtheriae, Nocardia
