Micro 1 - Bacterial Basics Flashcards
Which type of bacteria has a fixed Peptidoglycan layer AKA cell wall?
G(+)
Which type of bacteria has Lipoteichoic acid and what does it do?
G(+). Contains lipids and teichoic acid. It induces IL-1 and TNF-alpha.
What are three acute phase cytokines?
- IL-1
- IL-6
- TNF-alpha
What bacterial structure mediates adherence of bacteria to the surface of a cell?
Fimbriae. They are hair-like structures that allows bacteria to colonize membranes throughout the body.
What do G(-) bacteria have that G(+) don’t have on their structure?
- Outer membrane: Site of endotoxin (LPS). Also induces IL-1 and TNF-alpha.
- Periplasmic space: Site of beta-lactamase.
What do pilli in the bacterial membrane do?
Serves to link bacteria in conjugation: allows transfer of DNA from one bacteria to another.
What is glycocalyx?
It is a gelatinous, polysaccharide coating that aids in attachment to foreign material. It can be either in capsule form or biofilm/slime.
What is the name for glycocalyx in an organized and firmly adherent?
Capsule.
What is the name for glycocalyx that is loosely adherent and less organized structure?
Biofilm/slime.
What is the Quellung reaction?
It is a test to see if the bacteria in question has a capsule or not. Anti-capsular serum is added to bacteria. If there is a capsule, it appears swollen under microscope.
[Quellung equals SWELLung].
Name 8 encapsulated bacteria.
[Even Some Pretty Nasty Killers Have Shiny Bodies]
- E. coli (some strains)
- Strep. pneumoniae
- Pseudomonas aeruginosa
- Neisseria meningitidis
- Klebsiella pneumoniae
- Haemophilus influenzae type B
- Salmonella typhi
- Group B Streptococcus
What three big time baller bacteria that are encapsulated and cause high rate mortality, especially in patients with spleenectomy?
[SHiN]
- Strep pneumoniae
- Haemophilus influenza
- Neisseria meningitidis
What yeast is encapsulated and can be identified with India ink stain?
Cryptococcus neoformans.
What are the ribosomal subunit for prokaryotes?
70S (50S and 30S)
What are the ribosomal subunits for eukaryotes?
80S (60s and 40s)
What are plasmids?
Pieces of genetic material separate from chromosomal DNA. They can carry genes for antibiotic resistance or toxin production. They can be transferred during conjugation.
What is transformation?
DNA that has been released from a lysed cell and then taken up by a living bacterium. The DNA fragment is incorporated into chromosomal DNA. This is an option for only a few species of bacteria.
What bacterias have the transformation ability?
[SHiN]
Streptococcus pneumoniae
Haemophilus influenza
Neisseria meningitidis
What are transposons?
Small segments of DNA that can self-excise and relocate. Can carry antibiotic resistance or virulence factors.
What is transduction?
Phage attaches to bacterium and injects its DNA. Some bacterial DNA can be packaged inside the viral capsid. New phage injects viral and bacterial DNA into next bacterium.
What is special about Mycoplasma structure?
- Sterols
2. No cell wall
What is special about Mycobacteria structure?
- Mycolic acid
2. Rich in lipids, making it difficult in Gram staining.
Which type of bacteria produce spores?
- Bacillus
2. Clostridium
What color do G(+) bacteria stain?
Purple.
What color do G(-) bacteria stain?
Pink or red.
What are four bacteria that stain poorly on Gram stain?
- Mycobacteria
- Mycoplasma
- Treponema
- Legionella pneumophilia.
What bacteria are best to stain with Giemsa?
[Black Rock Can Play Three Hours]
- Borrelia
- Rickettsiae
- Chlamydia
- Plasmodium
- Trypanosomes
- Histoplasma
What structures can Periodic Acid-Schiff (PAS) stain?
Stains glycogen and mucopolysaccharides. Used to dianose Whipple’s disease caused by Tropheryma whippelii.
What is Ziehl-Neelsen stain used for?
To stain acid-fast organisms like Mycobacteria tuberculosis.
What is Indian Ink used for?
For fungus, especially Cryptococcus neoformans.
What is Silver stain used for?
For fungi, especially pneumocystis jirovecii. Used for Legionella too.
What bacterial structure protects against phagocytosis?
Capsule.
What bacterial structure provides rigid support to bacterial cell and protects against osmotic pressure difference?
Peptidoglycan layer of the cell wall.
What bacterial structure is the space between the inner and outer cellular membranes in G(-) bacteria?
Periplasmic space.
What is the bacterial form which provides resistance to dehydration, heat and chemicals?
Spore.
What bacterial structure forms attachment between two bacteria during transfer of DNA material (AKA conjugation)?
Pilus.
What bacterial structure has genetic material within bacteria that contains genes for antibiotic resistance?
Plasmid.
What stain is required to see Cryptococcus neoformans?
India Ink
What stain is required to see Pneumocystis jirovecii (PCP)?
Silver stain
What stain is required to see Chlamydia?
Giemsa stain.
By what method are plasmids exchanged between bacteria?
Conjugation which utilizes a pilus.
