Intro Flashcards Preview

Infectious Disease Unit 1 > Intro > Flashcards

Flashcards in Intro Deck (35)
Loading flashcards...
1
Q

Why ID important

A
  • Common
  • Diagnosable
  • Communicable
  • High Morbidity and mortality
  • Treatable
  • Newly emerging Pathogens
2
Q

what 3 variables affect development of infection/disease

A
  • Host (behavior, susceptibility, age, sex genetics, immune status)
  • Environment (geography, sanitation, crowding, pollutants, social, cultural, political, economic)
  • Agent (pathogenicity, prevalence, ecologic niche, tissue tropism, mechanism of immune control)
3
Q

how do you do a gram stain

A
  • Heat slide (kill/bind bacteria)
  • Crystal violet (binds peptidoglycan)
  • Add iodine to bind CV to gram positive cell wall
  • Rinse
  • add Acetone alcohol: removes stain from gram negative cells
  • Rinse
  • Add Safranin (counterstain)
4
Q

Gram Positive vs Gram Negative structure

A

Gram Positive: have Teichoic acid in cell wall as well as thick peptidoglycan layer

Gram Negative: Lack Teichoic acid but have outer membrane of Endotoxin/LPS with thin peptidoglycan wall

5
Q

Peptidoglycan in gram positive vs gram negative

A

up to 90% of cell wall in gram positive and up to 5-20% in gram negative

6
Q

Appearance of Gram positive vs negative on gram stain

A

positive– dark purple, because they hold onto the crystal violet

Negative: due to thin peptidyglycan layer, the acetone alcohol removes the crystal violet from gram negative cells, which then stain pink with Safranin (counterstain)

7
Q

Common Gram Positive cocci

A

Staph (clusters, pairs), Strep (pairs/chains)

Catalase +/-

8
Q

common Gram negative cocci

A
  • Neisseria- GC, meningococcus (CSF; lung)
  • Moraxella - pneumonia
  • Acinetobacter
9
Q

Gram positive rod examples

A

Listeria, Clostridium

10
Q

Gram negative rods

A

E. coli, Pseudomonas

lactose-ferment +/-

11
Q

Non-staining organisms

A
\+/- Legionella
Mycobacteria
Spirochetes
Rickettsia--intracellular
Mycoplasma
Chlamydia--intracellular
12
Q

Encapsulated organisms

A

S. pneumoniae, H. influenzae, Neisseria meningitidis, K. pneumoniae, Bacillus anthracis

13
Q

Multi-drug resistant organisms

A

M. tuberculosis, Ps. aeruginosa, methicillin-resistant Staph aureaus, Vancomycin-resistant enterococcus (VRE); S. pneumoniae

14
Q

Bacteria producing superantigens

A

S. aureus, Group A Strep

15
Q

Bacteria producing A-B toxins

A

V. cholerae, C. diphtheria

16
Q

Bacteria producing “other toxins” (not A-B or superantigens)

A

Clostridium

17
Q

Obligate intracellular organisms

A

Rickettsia, Chlamydia

18
Q

Facultative intracelular organisms

A

Salmonella, Mycobacteria, Legionella

19
Q

How to differentiate between gram negative rods

A

Lactose fermentation– most significant GNR are lactose fermentors

Pseudomonas,

20
Q

Lactose Fermenting GNR

A
E. coli
Klebsiella
Enterobater
Citrobacter
Arizona
21
Q

Non-lactose fermenting GNR

A

Pseudomonas aeruginosa, Salmonella, Shigella, H influenza, Acinetobater

22
Q

How to distinguish E coli from other lactose fermenting GNR

A

Indole– E coli is the only one that is positive (except a few Klebsiella species)

23
Q

Top lactose fermenting GNR

A

E. coli (flat), Klebsiela (mucoid), Enterobacter (mucoid)

24
Q

sources of GNR

A
  • intestine: appendix, diverticulitis, gallbladder (not Ps. aer.)
  • urine: +WBC, +sxs
  • lung/line (nosocomial)
25
Q

Is staph coagulase positive/negative

A

Aureus = positive

  • epidermidis (on skin) = negative
  • saprophyticus (UTI)= negative
  • lugdanensis = negative
26
Q

Staphylococcus bacteremia

A

100% of S. aureus are significant;

>90% of coagulase negative staph are contaminants

27
Q

Staph aureus

A
  • carrier
  • localized infection (boils, cellulitis)
  • disseminated (blood, heart, joints, metastatic)

causes abscesses due to coagulase– pus!

28
Q

When do you think of coagulase negative staph

A

plastic/metal in body (epidermidis)

2nd leading cause of UTI in sexually active females (S. saprophyticus)

29
Q

hemolysis status

A
  • alpha - green - S. pneumo, S. viridans
  • beta- clear (bad; Gr. A, B, C, G Strep; S. aureus)
  • gamma (none)- usually include Strept. Milleri (pus)
30
Q

Bad bugs

A

S. aureus (incl MRSA)
Strep pneumoniae
Group A Strept

31
Q

Less bad bugs

A
  • Coag-neg/S. epidermidis
  • Strep. viridans,
  • Enterococcus
32
Q

Wimpy bugs

A

P. acnes, diphtheroids

33
Q

Small GPR

A

Listeria (risk–prego), Diptheroids, P. acnes;actinomyces

34
Q

Large GPR

A

Clostridium, Bacillus sp.

35
Q

Anaerobes

A
  • 3% of + blood culture

-