Infectious Diseases Flashcards
What are the classes of pathogenic microorganisms?
Bacteria, viruses, parasites, fungi, prions
What are the eukaryotic pathogens? Prokaryote? Subcellular?
Parasites and Fungi
Bact
Prions and viruses
What are the characteristics of fungi?
Eukaryote; thicc carbohydrate cell wall; singlecellular to long, extensive chains
Cause Mycoses (superficial, subcutaneous, systemic)
What are the characteristics of parasitic pathogens?
Eukaryotic; multi-formed (from single cell-> multicellular)
What are the characteristics of bacteria?
Unicellular; prokaryotic; cell walls; no organelles/nucleus
What are the characteristics of prions?
Protein particles without a nucleus
- cause misfolding protein disease
- resistent to inactivation
What are the routes of transmission?
- Direct contact
- Contamination
- Airborne
- Exchange of fluids
- Vector (animal/arthropod)
How are bacteria differentiated in a lab setting?
Multitude of lab tests including gram stains, catalase, blood agar, etc. to differentiate presence or absence of enzymes, composition of cell wall, etc
What is a key characteristic of anaerobic gram + cocci?
Part of normal flora, but can cause infection when spread to a sterile area
What are the two types of gram + bacteria?
Cocci and bacili
What test can differentiate staph from strep?
Catalase test (staph is + and strep is -)
How can staph aureus be diff from other staph infections?
Coagulase (S. aureus = +)
What can staph aureus cause?
Superficial lesions, scalded skin syndrome, toxic shock syndrome
-systemic infections can also occur
What is an issue with the structure of biofilms?
Increased resistance to antimicrobials
-breakdown can lead to systemic infections
What methods can test efficacy of antibiotics on a bacteria?
Broth dilution, antimicrobial gradient, and disc diffusion
What antibiotics inhibit protein synthesis?
- aminoglycosides
- chloramphenicol
- macrolides
- streptothricin
- tetracycline
What antibiotics inhibit DNA/RNA synthesis?
- Quinolones
- Rifampin
What antibiotics interfere with the cell wall?
- Beta-Lactams
- Glycopeptides
What ABX inhibits energy metabolism?
- Sulfonamides
- Trimethoprim
What are some ways bacteria can resist antibiotics?
Changes of permeability to cell wall
- Efflux of ABX
- Enzymatic modification
- degredation of ABX
- Modification of ABX target
What are three sources of gene transport for bacterii?
Conjugation (bacteria sex), transformation (environment), transduction (bacteriophage)
What kind of hemolysis is clear and complete lysis of RBC?
Beta-hemolytic
What type of hemolysis is partially lysed RBC?
Alpha-hemolytic (green)
What type of hemolysis is associated with no hemolytic activity?
Gamma-hemolytic
What are ways to test for type of strep infection?
Colony morphology, hemolytic patterns, biochem reactions, serological specificityq
What is the most common “strep fever” strain?
Strep pygenes
- beta-hemolytic
- gram +
- “clumped” colony
What does strep pneumoniae cause?
Pneumonia, menengitis, etc
- A-hemolytic
- Optochin sensitive
- Gram +
What are some gram - cocci that are most clinically foundational?
Neisseria (gonorrhoeae/meningitidis)
Moraxella (catarrhalis)
T or F: Gram - is festidious and requires a specific medium to grow.
True
What are the two most common plates used to diff gram - species?
Blood and chocolate agar
What two sub-tests can diff niseria species?
Oxidase and catalase
What is the shape of Gram - bacilli?
Shorter, but still rod-like
What is a common gram - bacteria that is associated with food poisoning, gastroenteritis, and newborn meningitis
E. Coli
What diseases is pseudomonas aeruginosa associated with?
Lung and UTI
What is a high risk for gram - bacterial infection?
Hospitalization and catheters (most risk)
- recent sx
- war wounds
- dialysis
- mechanical ventilator
- decr immune system
Where can gram - samples be obtained?
Stool, blood, urine, sputum, lumbar puncture, abscess/lesion culture
What decides where a gram - specimen is obtained?
Nature of the symptoms (eg. diarrhea=stool sample)
What media should be used for gram -?
Blood or McConkey agar
What does a MacConkey agar measure?
Lactose fermentation and it has bile
Signs of what immune cell in a culture is indicative of bacterial infection?
Neutrophils
What are signs of viral infections in a blood culture?
Elevated leukocyte counts
What type of gram bacteria is most common in UTIs?
Gram -
