1/31/17 Mulvey Genetics 2 Pathogenesis TEST #1 Flashcards
What are the three mechanisms of Horizontal Gene Transfer?
- Bacterial Transformation
- Bacterial Transduction
- Bacterial Conjugation
What is Bacterial Transformation?
-DNA is taken up directly by cells
If bacteria are able to take up DNA they are said to be what?
-Competent
What are some naturally competent bacteria?
- Bacillus subtilis
- Streptococcus pneumoniae
Which strain of Streptococcus pneumoniae is virulent?
-Smooth strain because of capsule
What is transduction?
-Transfer of DNA mediated by bacteriophages
Where do viruses replicate is Transduction?
-Within bacteria
What are the two life cycle phases of the phage?
- Lytic
- Lysogenic
What carries important fitness and virulence determinants in the phage life cycle?
-Prophage in the lysogenic cycle
What is bacterial conjugation?
-Bacterial sex when one bacteria can make a pilus to grab onto another bacteria
What type of plasmid contains tra genes for transfer and are capable of conjugation and result in the expression of sex pili?
-Fertility F-Plasmids
What type of plasmid contains genes that code for bacteriocins and some of these are also toxic to host cells?
-Col plasmids
What type of plasmid encodes virulence factors and can convert a bacterium into a pathogen?
-Virulence plasmids
What type of plasmids contain genes that provide resistance against antibiotics or poisons?
Resistance (R) plasmids
What are Transposable elements?
-DNA elements that move from one place in bacterial DNA to another
What can transposable elements transfer and disrupt?
-Genes to a new location or disrupt genes when they insert
T/F Transposable elements do not carry virulence and antibiotic resistant genes
- False
- They can carry virulence and antibiotic resistant genes
How are pathogenicity islands acquired?
-Horizontal Gene Transfer
When the host receives goods and services while bacteria may receive shelter, nutrients, transport and other things what is that known as?
-Mutualistic symbiosis
What is commensalism?
-Bacteria benefit while host is unaffected
What is it known as when damages directly or indirectly affect the host by stimulation of host inflammatory responses?
-Disease
What is an organism which, under normal circumstances does not cause disease but can be pathogenic under some conditions?
- Opportunists
- Pathobionts
What microbiota is the largest and most studied in the body?
-Gastrointestinal
T/F You have increasing number and diversity of microbiota as you descend the GI tract
True
T/F Gastrointestinal microbiota helps to extract energy and nutrients from food we eat
True
What is colonization resistance?
-Microbiota inhibits colonization by newcomers
T/F If you take an antibiotic you can kill some of the bacteria in you gut leaving space for other more pathogenic bacteria to grow.
True
Is clostridium difficle gram positive or negative and anaerobic or aerobic?
-Gram positive anaerobe
What does clostridium difficile cause pathogenesis?
-Only following antibiotic treatment that depresses the rest of the microbiota of the gut
What are two antibiotics that clostridium difficile are associated with?
- Clindamycin
- Fluoroquinolones (Cipro)
What are three symptoms of Clostridium difficile and Pseudomembranous colitis?
- Diarrhea
- Abdominal pain
- Fever
What are three reasons that C. difficile can survive antibiotics?
- Resistance genes
- Biofilm formation
- Spore formation
When do clostridium difficile spores form?
- When there is a shortage of nutrients
- Antibiotic treatments
What do the spores multilayered protective coat consist of?
- Cell membrane
- Thick peptioglycan mesh
- Another cell membrane
- Wall of Keratin like protein
- Exosporium
How do you kill spores?
-Autoclaves
T/F Most antibiotics, hand sanitizer, isopropanol/ethanol will not kill spores
True
What are two medically important spore forming bacteria?
- Clostridium spp
- Bacillus spp.
What type of bacteria has nosocomial infections from bacterial spores?
-C. difficile
T/F the ability to outcompete commensals at many stages facilitate bacterial infection and survival within a host
True
T/F The attachment to host cells and tissues via adhesions increase the odds of not getting a bacterial infection
False
They facilitate bacterial infection and survival
What do some bacteria possess that prevent the uptake and destruction by phagocytes?
-Virulence factors
T/F Bacteria try to survive in the extracellular environment by having the ability to vary surface exposed antigens that allows outgrowth of antigenically novel clones (antigenic variation, phase shifting).
True
What are three ways that bacteria can survive within extracellular environments?
- Capsule
- Antigenic variation
- Secretion of molecules that interfere with host defenses
Is Listeria monocytogenes a gram positive or gram negative anaerobe?
-Gram positive
What are toxins?
-Virulence factors that may or may not be excreted that are toxic to human, animal, or plant cells
What do toxins cause in the host?
-Aberrant activation of host inflammatory responses
What do A-B type toxins include?
-Single chain and multi subunit toxins
What can LPS cause?
-Septic Shock
Super antigens are what type of toxin?
-Exotoxin
What do super antigens bind to?
-MHC class II
When the super antigen forms a bridge between the APC and T cells what does that result in?
-Massive outpouring of cytokines
What is the most infamous pathogen associated with super antigens?
-Staphylococcus aureus
What does staphylococcus aureus cause?
- Food poisoning
- Bacteremia/sepsis
- Toxic shock syndrome
- Abscesses
- Cellulitits
T/F Together Hospital acquired MRSA and Community acquire MRSA are responsible for more deaths in US than HIV?
True
What is the A subunit responsible for in A/B toxins?
-Enzymatic activity
What is the B subunit responsible for in A/B toxins?
-Mediates binding to a specific receptor and transfer of the A subunit across the membrane
