Intro to Infectious Disease Flashcards
Basis for gram staining
- differentiate bacteria by chemical and physical properities of cells walls via detection of peptidoglycan
- gram-positive = blue on gram stain
- gram-negative = pink on gram stain
4 basic divisions of bacteria
- Gram-positive
- cocci
- rods
- Gram-negative
- cocci
- rods
Important gram-positive cocci
- Staph Aureus → catalase + / pairs & clusters / coagulase +
- BAD!!!
- Staph other → pairs & clusters /coagulase -
- not as bad
- Strep → catalase - / pairs & chains
Important gram-negative cocci
- Neisseria
- Moraxella
Important gram-negative rods
- E. Coli, Pseudomonas → divide into Lactose-fermenters +/-
- UTI, Abd, nosocomial
Important gram-positive rods
- Listeria
- Clostridium
Important non-staining bacteria
- Gram (+): M. tuberculosis
- No cell wall: Mycoplasma, Chlamydia
- Gram (-) but too small: Rickettsia, Spirochetes (Syphilis)
- Gram (-) : Legionella
Lactose-fermenting bacteria
- E coli
- Klebsiella
- Enterobacter
- Citrobacter
NonLactose-fermenting bacteria
- Pseudomonas aeruginosa
- Oxidase (+), strict aerobe
- Salmonella
- Shigella
“Four questions” in the evaluation of patient w/presumed infectious disease
- First, find out chief complaint: Fever, MS change, cough, diarrhea, rash, ↑/↓ WBC, low BP, etc.
- 1) Is it infection?
- 2) Where is it?
- 3) What are the bugs at this site?
- 4) What are the drugs?
Gram-positive vs. Gram-negative bacterios
- Gram-positive (blue on gram stain)
- Teichoic acid
- Thick PG Cell wall
- (accessible outer PG)
- Gram-negative (pink on gram stain)
- LPS
- Thin PG Cell wall
- (PG covered by membrane [porins])
Common syndromes associated w/S. auresu
- Localized infection (boils, cellulitis)
- Disseminated infection
- blood, heart, joints, metastatic
Common syndromes associated w/coagulase-negative staph.
- infection @ prosthetics
- Where is the plastic?
- Where is the metal?
Common syndromes associated with Group A Step
- Group A strep = S. pyogenes
- Bacteremia, Sepsis
- Rheumatic fever
- Acute IE
- Pneumonia/empyema
- TSS
- Necrotizing fasciitis
Syndromes associatied w/gram-negative cocci
- gonorrhea
- meningitis
- pneumonia
Syndromes associatied w/gram-negative rods
- UTI
- Abdominal infections
- nosocomial infections
Syndromes associatied w/gram-positive cocci
- Cellulitis
- endocarditis
- abscess
Syndromes associatied w/gram-positive rods
- Meningitis
- fasciitis
Evidence of infection in Hx
- -Acute (±)
- Susceptible host
- Ill Contact
- Travel
Evidence of infection in PE
- -Fever (±)
- -Inflammation (±)
- Pus
- -Focal/source
Evidence of infection in Labs
- - WBC (left shift; toxic granulations)
- - CRP, ESR
- Imaging
- Pyuria
