Bacteria Lecture / CMMRS

Question 1

What are the 6 most medically relevant gram positive bacteria?

what are the three groups?

Answer 1

Group 1: Cocci shaped

Streptococcus (and Enterococcus) –> form strips of cocci

Staphylococcus –> form clusters of cocci

Group 2: Spore forming Bacilli (rods)

Bacillus

Clostridium

Group 3: non-spore forming bacilli (rods)

Corynebacterium

Listeria

Question 2

What are the 3 exceptions to gram negative or gram positive? why?

Answer 2

Mycobacteria

Spirochetes

Mycoplasma

Question 3

what are the Mycobacteria?

what do they stain better with?

what do they cause (2 things)

Answer 3

weakly gram-positive but stain better with an “ACID FAST STAIN”

tuberculosis + leprosy

Question 4

What are the spirochetes?

how do you visualize them?

what makes them different that makes them part of the “other” category?

what kind of flagella do they have?

Answer 4

gram negative cell wall but are TOO SMALL to be seen with the light microscope and thus must be visualized with a DARKFIELD MICROSCOPE.

have LPS outer lipoprotein membrane like gram negative, but have an ADDITIONAL phospholipid rich outer membrane with few exposed proteins as a “stealth” mechanism

“periplasmic flagella” which are found on the sides of the spirochete.

Question 5

What are the mycoplasma?

Answer 5

they do NOT have a cell wall

they only have a simple cell membrane, and thus are NEITHER gram positive or negative.

Question 6

differences between eukaryotes and prokaryotes?

Answer 6

prokaryotes –> 70S ribosome

Eukaryotes –> 80S ribosome

Question 7

What does Catalase do?

how is it practically employed?

Answer 7

breaks down hydrogen peroxide (2H2O2 –> H2O + O2)

looking on a Petri dish you’ll see bubbling

Question 8

What are the Obligate aerobes? 2 gram +, 5 gram -, 2 acid fast

what does this mean?

Answer 8

Nocardia, Bacillus Cereus (gram +)

Neisseria, Pseudomonas, Bordetella, Legionella, Brucella (gram -)

Nocardia + mycobacterium

require oxygen as the final electron acceptor.

Question 9

What are the facultative anaerobes? (5 gram+, 1 other, what about gram -?)

what does this mean?

Answer 9

Staphylococcus, Bacillus Anthracis, Corynebacterium, Listeria, Actinomyces

mycoplasma (no cell wall)

MOST gram - rods are facultative anaerobes

they’re aerobic, but can grow in an anaerobic environment (PREFER aerobic)

Question 10

What are the microaerophilic bacteria (aerotolerant)? (2 gram +, 1 other, 1 gram-)

what does this mean?

Answer 10

Enterococcus, some streptococcus

spirochetes

Campylobacter

fermentation and have NO electron transport system. tolerate low oxygen because they have superoxide dismutase.

Question 11

What are the 2 obligate anaerobes?

what does it mean?

Answer 11

Clostridium –> gram +

Bacteriodes –> gram -

HATE oxygen and have no enzymes to defend against it.

Question 12

Neisseria gonorrhea –> why are pili (adherence factors or adhesins) vital to their ability to cause disease?

what about E. coli and Campylobacter jejuni)?

what about Bordetella pertussis?

Answer 12

so it can bind to cervical cells and buccal cells to cause gonorrhea.

they need to adhere to bind to the Intel epithelium to cause diarrhea

uses its adhesion to bind to ciliated respiratory cells and cause whooping cough.

Question 13

Why is Bacillus anthracis unique?

Answer 13

usually capsules on bacteria are of sugar moieties, but this is the only one that the capsule is made of AMINO ACID RESIDUES

Question 14

What two important tests are used to visualize capsules under the microscope? include the classic species associated with it

Answer 14

India ink Stain –> this stain is not taken up by the capsule, so the capsule appears as a transparent halo around the cell –> Cryptococcus

Quellung reaction –> bacteria are mixed with antibodies that bind to the capsule.. when bound the capsule swells with water and we can see this.

Question 15

Endospores are only formed by what 2 genera of bacteria?

what properties do they have?

Answer 15

AEROBIC Bacillus and ANAEROBIC Clostridium

they are metabolically dormant forms of bacteria resistant to heat (boiling), cold, drying, and chemical agents.

Question 16

What is a plasmid?

what does it typically have? ex?

Answer 16

non chromosomal DNA that replicates autonomously.. SMALL, CIRCULAR dsDNA –> genetic material for bacteria

Typically has advantageous genetic material

antibiotic resistance

Question 17

what replication does bacteria use?

Answer 17

binary fission

Question 18

What are the different plasmids?

Answer 18

F Plasmid – FERTILITY. conjugation - formation of sex pilus

R Plasmid – RESISTANCE – antibiotic resistance

Col Plasmid – produce bacteriocin to annihilate surrounding microbes

Question 19

When we have endotoxin (LPS) - Lipid A in a gram - cell, –> what happens when the cell is lysed?

Answer 19

when lysed, fragments with lipid A are put into circulation and lead to SHOCK

Question 20

What are the 6 different virulent cell structures?

what does each do?

Answer 20

Flagella – motility (chemotaxis)

Pili (fimbriae) – Adherence, sex

Capsule – Evade phagocytosis

Endospores – Dormant, resistant structures to protect genetic material

Facultative Intracellular – phagocytize for survival!!

Biofilm formation – extracellular polysaccharide “net” that allows for adhesion and protection.

Question 21

What are Exotoxins?

what are types of these? (4)

what type are they primarily found in?

Answer 21

Proteins RELEASED by both gram- and gram+ bacteria

Neurotoxins (motor-end plate, nerves)

Enterotoxins (GI)

Pyrogenic exotoxins (fever, rash, TSS)

Tissue invasive exotoxins

mostly GRAM +

Question 22

What are the three main Staphylococcus species?

Answer 22

Staphylococcus aureus

Staphylococcus epidermis

Staphylococcus saprophyticus

Question 23

Staph aureus:

1) what do they look like under the microscope? what about grossly?
2) what are they (+) for?
3) what helps protect it?
4) what helps destroy tissues?

Answer 23

G+ cocci in CLUSTERS, golden appearance

Coagulase +, Catalase +, Beta hemolytic

Protein A (antibody –> main virulence factor), hemolysis, leukocidins, penicillinase

Hyaluronidase, staphylokinase, lipase

Question 24

Staph epidermis:

1) what do they look like under the microscope? what oxygen do they prefer?
2) what are they (+) for?
3) what do they LOVE harboring in? (3 things). where else can it be found?
4) how does this separate from staph aureus?
5) what is a key feature to this bug?

Answer 24

Gram+ cocci in CLUSTERS, facultative anaerobe

Catalase +, Urease +

indwelling devices, shunts, catheters –> ortho’s worst nightmare.

can be a CONTAMINANT in blood cultures

Coag (-)

BIOFILMS!

Question 25

Staphylococcus Saprophyticus:

1) what do they look like under the microscope? what oxygen do they prefer?
2) what are they (+) for?
3) what are they the second most leading cause of? what’s #1?
4) who often gets this? what is it also called?

Answer 25

Gram + cocci in clusters, facultative anaerobe

Catalase +, urease +, coag -

UTIs behind E. coli

sexually active younger women

“honeymoon cystitis”

Question 26

What are the 5 Streptococci to know?

Answer 26

S. pyogenes
S. agalactiae (GBS)
S. Viridans
S. Pneumoniae
Group D strep (enterococcus and S. Bovis)