Module 16 Flashcards
What are the different virulence factors that bacteria use to cause infection?
Fimbriae and pilli
Flagella
Secretion of toxins and enzymes
Invasion (think TB)
Hair-like structures that project from the surface of bacterial cells.
Fimbriae and pilli
Allow bacteria to attach to certain sites in out body so they are not washed away.
Fimbriae/pilli
Describe how E. coli use virulence factors to cause infection.
Use fimbriae/pilli to attach to the urogenital tract to cause bladder infections
Virulence factor that bacteria use to swim in aqueous environments to a site where they may survive or cause infection.
Flagellum
Describe how toxins not produced by bacteria inside the body can cause toxic reactions.
In the case of food poisoning, toxins are left in food and, when ingested, cause toxic effects
How can bacterial enzymes work as virulence factors?
Can inactivate antibodies, breakdown tissues, etc.
Give examples of bacteria that use invasion as a virulence factor.
Salmonella - invade intestinal cells and cause diarrhea
TB - invade the lungs and hide inside our cells
Describe the major difference between gram positive and negative bacteria, and what colour each stains.
Gram positive - large peptidoglycan layer - stains purple
Gram negative - small peptidoglycan layer - stains pink
Differentiate gram negative and positive bacteria based on the following: Peptidoglycan/cell wall Major surface antigen Outer membrane Porins
Gram positive
- thick peptidoglycan layer (cell wall)
- Techoic acids are the major surface antigen - provide rigidity to cell wall
- No outer membrane
- No porins (few exceptions)
Gram negative
- thin peptidoglycan layer (cell wall)
- major surface antigen is LPS (structural component of outer membrane)
- outer membrane present
- has porins on outer surface - allow sugars, ions, and amino acids to enter
What are the typical signs of infection?
What groups may not show these? Why?
Typical signs of infection - local redness, fever, overall malaise, swelling
Newborns have poorly developed hypothalami, and the elderly may have decreased hypothalamic activity, and thus do not generate appreciable fever
Therapy is able to destroy the target without harming the host.
Selective toxicity
The major difference between mammalian cells and prokaryotic cells.
Mammalian cells do not have cell walls
What are the ways in which antibiotic therapy produces selective toxicity?
Disrupting the bacterial cell wall
Targeting bacterial enzymes (unique)
Disrupting bacterial protein synthesis (bacterial ribosomes are different than eukaryotic ones)
Ideally, bacteria are ________ prior to selection of the treatment.
identified
In general, ______ the bacteria to properly identify it will provide the best basis for selection of therapy.
culturing
In what cases would cultures not be able to be done?
Child ear infection - hard to obtain culture
LRT infections - too many bacteria to culture
Describe a bacteriostatic antibiotic.
Stops the growth and replication of bacteria
The immune system than attacks and remove the bacteria
Describe a bartericidal antibiotic.
Kill the bacteria
MIC
MBC
Minimum inhibitory concentration
Minimum bactericidal concentration
Use MIC or MBC
The _____ is most often higher than the ______, thus we use the ______ and then increase its concentration to determine the _____.
MBC
MIC
MIC
MBC
What are some infections that are difficult to treat (i.e. penetration of antibiotics to the site is limited)?
Meningitis UTIs Osteomyelitis Abscesses Otitis media
Infection of the meninges, which are the membranes that cover the ______ and ______ ______.
meningitis
brain
spinal cord
____________ meningitis is rare, but is more serious than ____________ meningitis.
bacterial
viral
The most common type of UTI is an infection of the _______, which may be caused by ________.
bladder
catheterization
Effective treatment of UTIs requires that an antibiotic reaches the urinary tract. Why is this limited?
Most drugs reaching the urinary tract do so in an inactive form
Infection of the bone.
Osteomyelitis
Infection of the middle ear.
More common in ________.
otitis media
children
Describe a case in which bactericidal antibiotics would be used instead of bacteriostatic antibiotics.
In immunocompromised patients, bactericidal antibiotics can be used.
Bacteriostatic antibiotics require the actions of the immune system, and thus cannot be used in immunocompromised patients
What are some examples of patients that could not use bacteriostatic antibiotics?
AIDS, organ transplantation, cancer chemotherapy, elderly patients
Bacteria that did respond to an antibiotic and have lost sensitivity over time.
Resistance
Antibiotic resistance can be acquired by three major mechanisms, what are they?
Reduction of the drug at the site of the target
Increased drug activation
Alteration of the bacterial target
What are some ways in which bacteria can reduce the amount of drug at the target site?
Efflux pumps
Decrease uptake of antibiotics
Give an example of increased drug inactivation in bacteria
Some bacteria produce beta-lactamase (penicillinase) which degrades antibiotics with beta-lactam rings (penicillins and cephalosphorins)
Give an example of alteration of the bacterial target in antibiotic resistance.
Mutation in ribosomal genes, altering the protein structure and rendering the antibiotic useless against it
What are four strategies to prevent bacterial resistance to antibiotics?
Prevent infection
Diagnose and treat infections effectively
Use antibiotics wisely (i.e. when necessary)
Prevent transmission
Most common antibiotic allergy
Penicillin
What are signs of allergy?
Hives Anxiety swelling of hands, feet, throat Difficulty breathing Hypotension
Most fatal antibiotic allergy reactions occur within _______ of dosing
20 minutes
What is another word for hives?
Urticaria
Most allergic reactions experienced by patients taking antibiotics are not true immune-mediated allergies.
These patients instead experience these symptoms.
Vomiting, diarrhea, non-specific rash
If your patient is having an allergic reaction, you should ____ the antibiotic _________, and monitor ______ _____.
Patients may required treatment with ________ and an _______.
stop immediately vital signs Diphenhydramine (Anti-histamine) Epipen
Similar to an allergy but develops 7-21 days after antibiotic exposure.
serum sickness
The body’s immune system improperly identifies a drug or drug-protein complex as harmful.
Serum sickness
What is the treatment for serum sickness?
Antihistamine (itching), analgesic (pain), corticosteroids (inflammation)
What are signs/symptoms of serum sickness?
joint pain, itching, hives, fever, rash, angioedema, enlarged lymph nodes
(Treatments for pain + allergy symptoms + immune reaction)
New type of infection that develops during the course of antibiotic therapy.
Superinfection
Risk factor for superinfection.
Use of broad spectrum antibiotics, which can kill normal bacterial flora and allow new bacteria to flourish and cause a new infection
What are some additional consequences of destruction of normal bacterial flora?
Reduced vitamin K synthesis and thus at higher risk for bleeding side effects (e.g. when taking warfaring)
Decreased drug metabolism, thus higher plasma drug levels and possible toxicity
Decreased enterohepatic recylcing (oral contraceptive failure)
Very rare but serious complication of antibiotic therapy. Symptoms include aplastic anemia, thrombocytopenia, agranulocytosis and leukopenia.
Bone marrow toxicity
What signs should patients look out for as they are signs of bone marrow toxicity?
Sore throat, easy bruising, fatigue
