Gill lecture 2 Flashcards
Which strep typically causes strep throat?
S. pyogenes
What can be a serious complication of multiple Group A Strep infections (Cohen also covered it)?
Rheumatic fever/rheumatic heart disease. Will also see glomerulonephritis (antibodies+strep caught in kidney basement membranes)
What is the primary virulence factor of strep pyogenes?
M-protein
Why can you get strep throat multiple times?
70 serotypes of M-protein
What does M-protein do?
inhibits phagocytosis and kills PMNs.
What are the two most predominant methods of diagnosis C. Difficile?
Culture and ELISA
Which drug is commonly used to treat C. difficile?
Metronidazole
What toxins must be recognized to confirm C difficile diagnosis?
Toxina A and B
T or F: Spore are the source of clostridium infections.
TRUE
Which neurons are blocked by tentanus toxin?
Inhibitory interneurons leading to inability to relax muscles (lockjaw, spastic paralysis)
What is in the tetanus vaccine? tetanus antoxin?
Vaccine - toxoid of tentanus toxin and protects from the action of the toxin but not against the bacterium itself. Antitoxin - for acute tetanus symptoms, pooled human hyperimmune gamma globulin
T or F: Children can get tentanus when born in unsterile environments.
True. Also if mothers have not been vaccinated against tetanus.
Which neurons are blocked by botulinum toxin?
Acetylcholinergic neurons (block transmission of Ach at the neuromuscular junction resulting in flaccid paralysis)
Where is C botulinum commonly found?
Home-canned products
T or F: Botulisms toxin is deactivated by cooking.
FALSE
Which organs are most commonly affected by C. perfringens?
Skin, then muscle and nerve
What toxin is released by C. perfringens?
Toxin A - major toxic factor, kills neutrophils
T or F: C. perfringens can produce enterotoxin.
TRUE
What is the difference between endotoxin, exotoxin, and enterotoxin?
Endotoxin - Lipid A part of the cell wall of G- bacteria, released only after the destruction of the bacterial cell wall. Exotoxin - secreted by a bacteria. Enterotoxin - type of exotoxin, targets the intestines
What is enterotoxin?
Produced when organism (such as C. perfringens), site of action is the small intestine.
T or F: C. perfringens can be part of normal flora?
TRUE
What group of strep is S. pyogenes part of?
Group A Strep
T or F: S. pyogenes will produce abscesses when infecting the skin.
False. Not generally associated with abcesses, no coagluase.
What kind of strep causes endocarditis?
Mostly Viridans streptococci
Why does viridans strep cause endocarditis?
Produces dextrans that allow it to adhere to damaged heart valves.
Where is viridans strep found in the normal flora of the human body?
The mouth. Dextrans allow them to adhere to teeth.
T or F: GI E. coli infection is often caused by drinking contaminated food and water.
TRUE
T or F: E coli that cause urinary tract infections are special.
True. These have special ability to adhere to urinary tract, specific interactions with bladder cells, and are typically hemolytic
What are the most common reasons for E coli abdominal infections?
surgical wounds, burst appendix, colon cancer
T or F: Pseudomonas aeruginosa cause infections in non-immunocompromised individuals.
FALSE
Which patients are you likely to see these P. aeruginosa?
Burn victims, cystic fibrosis
What is the time course of lung infections of cystic fibrosis patients?
Will have S. aureus infections early in life that will be well controlled by antibiotics. Later will get P aeruginosa infections resistant to anti-staph drugs. P. aeruginosa makes toxins and calls in immune response. These factors will cause the damage of the drug. Will frequently cause the death of these patients.
What are the gram negative rod genuses that we have to know?
E. coli and pseudomonas aeruginosa
What is the gram negative cocci genus that we have to know?
Neisseria
What is the key to infectivity of neisseria?
Pili (adherence, interferes with neutrophil killing)
Where does neisseria gonorrhoeae tend to cause infection?
Urinary tract and reproductive system (pelvic inflammatory disease)
Where do we see anaerobic infections?
Colon, mouth, female genital tract, skin
T or F: The anaerobes that are most commonly seen in infections are relatively aerotolerant.
TRUE
What bacteria is often cultured from anaerobic abcesses below the diaphragm?
Bacteroides fragilis
What are the obligate intracellular bateria?
Chlamydia trachomatis, Rickettsia
What is the bacteria without cell walls?
Mycoplasma pneumoniae
T or F: Rickettsia makes its own ATP.
False. Intracellular, uses host ATP
What practical implications must you be aware of when trying to make an intracellular pathogen diagnosis?
Difficult to culture an intracellular bacteria, need to choose an antibiotic that gets into eukaryotic cells
What disease are caused by chlamydia?
Trachoma (conjunctiva), genital infections
T or F: Mycoplasma pneumoniae is a common cause of pneumonia.
TRUE
How is mycoplasma pneumoniae infection diagnosed?
Serological tests, PCR. Difficult to get a culture due to special growth conditions and slow growth.
How to bacteria evolve?
Slowly by selection, faster by lateral transfer of genetic material
What does the bacterial chromosome encode?
Essential genes
What ways to bacteria carry genetic information? (3)
Bacterial chromosome, plasmid, bacterial viruses
What is the rate of spontaneous antibiotic resistance?
10^8-10^10. Fairly rare, very slow process.
What is the biological significance of being able to switch between genes by reorienting a promoter?
Confuses the immune system. While the immune system is focused on one version of bacteria, the other can flourish. An example is pili expression in gonorrhea.
What are transposable elements?
Segment of DNA contained within a bacterial or phage chromosome, it can be moved from one place to another.
Conjugative transposons - how do they work?
Mating experiment
What is a bacterial plasmid?
Self-replicating extrachromosomal DNA, often circular, not essential for viability (in a non-challenging environment), may encode a variety of functions including antibiotic resistance, virulence factors, metabolic functions. May or may not be self-transmissible.
What are self-transmissible plasmids?
Plasmids that can be transferred from on bacteria to another.
What are non-self transmissible plasmids?
Cannot be duplicated and transferred to other bacteria, but may be mobile and accidentally get passed along with a self-transmissible plasmid.
What are pathogenicity islands?
Sections of DNA that are found in some strains of a particular species that carry genes for pathogenesis/virulence.
How importance are phage DNA/plasmids in virulence?
Very
