Bacteria Lecture / CMMRS Flashcards
What are the 6 most medically relevant gram positive bacteria?
what are the three groups?
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
What are the 3 exceptions to gram negative or gram positive? why?
Mycobacteria
Spirochetes
Mycoplasma
what are the Mycobacteria?
what do they stain better with?
what do they cause (2 things)
weakly gram-positive but stain better with an “ACID FAST STAIN”
tuberculosis + leprosy
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?
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.
What are the mycoplasma?
they do NOT have a cell wall
they only have a simple cell membrane, and thus are NEITHER gram positive or negative.
differences between eukaryotes and prokaryotes?
prokaryotes –> 70S ribosome
Eukaryotes –> 80S ribosome
What does Catalase do?
how is it practically employed?
breaks down hydrogen peroxide (2H2O2 –> H2O + O2)
looking on a Petri dish you’ll see bubbling
What are the Obligate aerobes? 2 gram +, 5 gram -, 2 acid fast
what does this mean?
Nocardia, Bacillus Cereus (gram +)
Neisseria, Pseudomonas, Bordetella, Legionella, Brucella (gram -)
Nocardia + mycobacterium
require oxygen as the final electron acceptor.
What are the facultative anaerobes? (5 gram+, 1 other, what about gram -?)
what does this mean?
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)
What are the microaerophilic bacteria (aerotolerant)? (2 gram +, 1 other, 1 gram-)
what does this mean?
Enterococcus, some streptococcus
spirochetes
Campylobacter
fermentation and have NO electron transport system. tolerate low oxygen because they have superoxide dismutase.
What are the 2 obligate anaerobes?
what does it mean?
Clostridium –> gram +
Bacteriodes –> gram -
HATE oxygen and have no enzymes to defend against it.
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?
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.
Why is Bacillus anthracis unique?
usually capsules on bacteria are of sugar moieties, but this is the only one that the capsule is made of AMINO ACID RESIDUES
What two important tests are used to visualize capsules under the microscope? include the classic species associated with it
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.
Endospores are only formed by what 2 genera of bacteria?
what properties do they have?
AEROBIC Bacillus and ANAEROBIC Clostridium
they are metabolically dormant forms of bacteria resistant to heat (boiling), cold, drying, and chemical agents.
What is a plasmid?
what does it typically have? ex?
non chromosomal DNA that replicates autonomously.. SMALL, CIRCULAR dsDNA –> genetic material for bacteria
Typically has advantageous genetic material
antibiotic resistance
what replication does bacteria use?
binary fission
What are the different plasmids?
F Plasmid – FERTILITY. conjugation - formation of sex pilus
R Plasmid – RESISTANCE – antibiotic resistance
Col Plasmid – produce bacteriocin to annihilate surrounding microbes
When we have endotoxin (LPS) - Lipid A in a gram - cell, –> what happens when the cell is lysed?
when lysed, fragments with lipid A are put into circulation and lead to SHOCK
What are the 6 different virulent cell structures?
what does each do?
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.
What are Exotoxins?
what are types of these? (4)
what type are they primarily found in?
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 +
What are the three main Staphylococcus species?
Staphylococcus aureus
Staphylococcus epidermis
Staphylococcus saprophyticus
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?
G+ cocci in CLUSTERS, golden appearance
Coagulase +, Catalase +, Beta hemolytic
Protein A (antibody –> main virulence factor), hemolysis, leukocidins, penicillinase
Hyaluronidase, staphylokinase, lipase
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?
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!
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?
Gram + cocci in clusters, facultative anaerobe
Catalase +, urease +, coag -
UTIs behind E. coli
sexually active younger women
“honeymoon cystitis”
What are the 5 Streptococci to know?
S. pyogenes S. agalactiae (GBS) S. Viridans S. Pneumoniae Group D strep (enterococcus and S. Bovis)
