Final Exam: BacT/Mycology overview Flashcards
T/F: Histones are present in bacteria
FALSE
only present in eukaryotic cells
What is unique to gram positive bacteria?
Teichoic acid
T/F: Bacteria have chromosomes and ribosomes
TRUE
Mycobacteria stains gram positive or negative? Why?
Gram positive - due to their cell wall
What is unique to mycobacteria?
Mycolic acid
*no cell membrane
Why do bacteria stain gram positive?
Due to the presence of a thick peptidoglycan layer
**purple
What is unique to gram negative bacteria?
Lipopolysaccharide
Which of the following processes is the least likely virulence mechanism of bacteria?
- Flagella - mobility
- Fimbria - adherence
- Bacterial protein production by ribosomes
- Capsule - to evade phagocytosis
3 - this is something done but nearly all bacteria; doesn’t really increase virulence
How do prokaryotic cells replicate?
Binary fission
No meiosis
Do prokaryotes have a cytoskeleton?
NOPE!
Is the cell wall of eukaryotes simple or complex?
What about the cell wall of prokaryotes?
Eukaryotes - chemically simple when present
Prokaryotes - chemically complex
What syndrome can be caused do to the endotoxin, Lipid A, when released in large amounts?
What bacteria produce this endotoxin?
Toxic shock syndrome
Gram Negative
What components make up the triangle of tragedy?
Host - pathogen - environment
If these are not in balance –> disease
What is a pathogen?
A microbe that can cause disease
What is pathogenesis?
Mechanisms by which disease is caused
What is virulence?
Degree of pathogenicity; includes severity
What are virulence factors?
Properties or traits found in isolates that cause dz but which are not found in isolates of the same species that lack the ability to cause dz
Opportunistic pathogens require hosts to have a or many ________ to become infected
Predisposition(s)
immune compromised
age
poor nutrition etc etc
What two types of pathogens will produce a distinct disease?
Obligate and primary pathogens
What two types of pathogens cause “non-specific” disease?
Opportunistic and non-pathogenic
What does it mean if a bacteria is an obligate intracellular?
Does not multiply outside of the host cell
What makes facultative intracellular bacteria special?
They can be both intracellular and extracellular
Often will hide in macrophages to evade the immune system
What is the sequence of events in bacterial/fungal pathogenesis?
Entry into the host Evade host defenses Colonize the host systems Multiply Exert damage in the host Transmit to other host = INFECTIOUS
What are some consequences of bacterial infection?
Infection –> Dz –> Recovery
Infection –> Dz –> Death or disability
Infection –> Dz –> persistent infection (transmission or carrier stage)
What do spirochetes have that spiral bacteria do not?
Endoflagella/axial filaments
What are some virulence factors that bacteria may have?
Flagella - motility Fimbriae - adherence Capsule - evade phagocytosis Toxins - endo and exotoxins Superantigens Quorum sensing Biofilms
T/F: Any bacteria can opportunistically infect any of the body systems
TRUE
What do fungi have in their cell membrane that is unique?
Sterols
What is the unicellular form of fungi called? Multicellular fungi?
Unicellular = yeast Multicellular = mold and hyphae
What are dimorphic fungi?
Exist as yeast and mold depending on the temperature
Fungi can reproduce via..?
Sexual and asexual reproduction
Budding, fragmenting
What are 4 dimorphic fungi?
Blastomyces dermatitidis
Histoplasma capsulatum
Coccidioides immitis
Sporothrix schenckii
What are the fungus-like organisms discussed in class? (3)
Pythium and Lagenidium (water molds)
Prototheca - algae
When should your specimen collection tube NOT be air tight?
When sending off a sample for fungal culture - do not want any moisture to build up
Heavy pure culture of a bacteria is indicative of a ____________.
Infection
Isolation of three or more types of organisms is most likely are result of ______.
Contamination
Antibody titers:
Patient X has a titer of 1/300
Patient Y has a titer of 1/800
Which patient has a higher antibody titer?
Patient Y
*can sense the presence of antibodies after an 800 time dilution
T/F: All antimicrobials are antibiotics, but not all antibiotics are antimicrobials
FALSE
All antibiotics are antimicrobials
Not all antimicrobials are antibiotics
**ABs are produced by a naturally occurring microorganism
T/F: Mycobacteria are the only acid fast positive bacteria
False
What antimicrobials have a MOA that involves the cell wall/cell membrane?
Beta lactams (penicillin, ampicillin, cephalosporins, carbapenems)
Glycopeptides (Vancomycin)
Bacitracin
Polymyxin
What antimicrobials have a MOA that targets protein synthesis?
Tetracyclines Macrolides Aminoglycosides Chloramphenicols Lincosamides Streptogramins
What antimicrobials have a MOA that targets DNA synthesis?
Sulfonamides
Fluroquinolons (enrofloxacin)
Nitroimidazoles/Nitrofurans
*Rifampin (RNA)
What drugs target ergosterols in the cell wall of fugi?
Polyene
Azoles
What is the MIC?
Minimum inhibitory concentration: Min. amt. of a drug required to inhibit bacterial growth
What is a susceptibility break point and what are some examples?
A drug concentration above which an organism is considered resistant and at/or below this value, the organism is susceptible to the drug
Ex: Susceptible, intermediate, Resistant
What is innate antimicrobial resistance and acquired resistance?
Innate = preexisting genomic property
Acquired = acquired by a mutation(s)
T/F: The Kirby Bauer disc test results in a MIC
False
just get breakpoints according to zone size
T/F: The broth dilution test will result in a MIC
TRUE
What are some non-therapeutic uses of antimicrobials?
Growth promotion
prophylactic
metaphylactic
What is the difference between bactericidal and bacteriostatic antimicrobials?
When would you want to avoid using bacteriostatic ABs?
Cidal = kills bacteria Static = inhibits growth
Avoid bacteriostatic ABs in patients that are immunocompromised or when infections are in CNS (want to get rid of all the bacteria)
- What kind of organisms need oxygen for growth?
- What organisms do not require or utilize oxygen for growth?
- What organisms do not require oxygen, but can utilize it for growth?
- Aerobic, microaerophilic, capnophilic (grow best with CO2)
- Obligate anaerobe, aerotolerant anaerobe
- Facultative anaerobe
What happens in the lag phase, log phase, stationary phase, and decline phase of bacterial growth?
- lag: no growth
- log: Exponential growth
- stationary: plateau
- Decline: death
When are spores produced?
When the environment is not ideal for bacteria survival. Spores are highly resistant dormant forms of bacteria.
Acid fast positive stain _______
Acid fast negative stain ______
Positive = pink
negative = blue
Gram negative stain ______
Gram positive stain _______
Negative = pink
Positive = violet/blue
