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Flashcards in Microbiology Deck (186)
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1

Gram positive structure

Cell wall present; major surface antigen

Composition:
- Peptidoglycan
- Lipoteichoic acid--> TNF, IL-1 induction

2

Gram negative structure

No cell wall, only outer membrane
- Site of Endotoxin= LPS (lipopolysaccharide)= major surface antigen

Composition:
- Lipid A--> activate macrophages--> increased TNF and IL-1
- Antigen= O polysaccharide
- Periplasm= space between cytoplasmic membrane and outer membrane; contains hydrolytic enzymes (beta-lactamases)

3

Spore structure

Resistant to dehydration, heat, chemicals
- Must autoclave (121 C for 15 min)

Composition:
- Keratin-like coat
- Dipicolinic acid core
- Peptidoglycan

Seen in:
- Soil: B. anthracis, Clostridium perfringens, c. tetani
- Other: B. cereus, C. botulinum, Coxiella burnetti

4

Gram-positive cocci

Staphylococcus
Streptococcus

5

Gram-negative cocci

Neisseria

6

Gram-positive rod

Clostridium
Corynebacterium
Bacillus
Listeria
Mycobacterium (high lipid= acid fast)
Gardenerella (gram variable)

7

Gram-negative rods

Almost everything else:
1. Enterics:
- E. Coli
- Shigella
- Yersinia
- Klebsiella
- Proteus
- Enterobacter
- Serratia
- Vibrio
- Campylobacter
- Helicobacter (silver stain+)
- Pseudomonas
- Bacteroides

2. Respiratory:
- Haemophilus (pleomorphic)
- Legionella (intracellular; silver stain +)
- Bordetella

3. Zoonotic
- Francisella
- Brucella
- Pasteurella
- Bartonella

** resistant to Penicillin G (gram-negative outer membrane inhibits Pen G/Vanco from entering)
** Susceptible to Ampicillin, amoxicillin

8

Spirochetes

Gram-negative (too thin)
- Leptospira
- Borrelia
- Treponema

9

Pleomorphic bacteria

Giemsa-stain
- Rickettsiae (intracellular)
- Chlamydiae (intracellular, no muramic acid)

10

Bacteria with no cell wall

Mycoplasma= no staining
- Sterols with no wall

11

Giemsa-positive

Certain Bugs Really Try my Patience:
- Chlamydia
- Borrelia
- Rickettsiae
- Trypanosomes
- Plasmodium

12

Carbol Fuschin stain (Ziehl-Neelsen)

Acid-fast organisms
- Nocardia
- Mycobacterium

13

India ink positive

Cryptococcus neoformans
- can also stain with mucicarmine

14

Exotoxin

Derived from gram + and gram -
- Secreted from cell
- Polypeptide
- Located on plasmid/bacteriophage
- Highly toxic
- Antigenic= Induces antitoxins (titer antibodies)
- Vaccine= toxoids
- Destroyed at 60C (besides staph enterotoxin)

Seen in: Tetanus, botulism, diphtheria

15

Endotoxin

LPS= structural component of outer cell membrane in gram negative; released when lysed (NOT secreted)

Activates:
1. Macrophages:
- IL-1--> fever
- TNF--> fever, hypotension
- NO--> hypotension
2. Complement
- C3a--> hypotension, edema
- C5a--> neutrophil chemotaxis
3. Tissue factor
- Coagulation cascade--> DIC

- Located on Bacterial chromosome
- Low toxicity
- Causes: Fever, shock
- Mode of action:Induces TNF and IL-l
- Antigenic: Poorly antigenic
- Vaccines= none
- Stable at 100C for 1 hour

Seen in: meningococcemia, gram-negative sepsis

16

Obligate aerobes

Nagging Pests Must Breathe
- Nocardia
- Pseudomonas aeruginosa
- Mycobacterium tuberculosis (apices of lung)
- Bacillus

17

Obligate anaerobes

Can't Breathe Air
- Clostridium
- Bacteroides
- Actinomyces

Seen in GI tract, pathogenic anywhere else
** Can't treat with aminoglycosides= need O2 to enter cell

18

Obligate intracellulars

Rickettsia
Chlamydia

19

Facultative intracellular

Now Listen Sally, Yer Friend Bruce Must Leave

- Neisseria
- Listeria
- Salmonella
- Yersinia Pestis
- Francisella
- Brucella
- Mycobacterium
- Legionella

20

Encapsulated bacteria

Positive Quellung reaction--> swelling

SHiNE SKiS
- Streptococcus pneumoniae
- Haemophilus infiuenzae type B
- Neisseria meningitidis
- Escherichia coli
- Salmonella
- Klebsiella pneumoniae
- group B Strep.

21

Catalase-positive

Degrades H2O2 before converted to microbicidal products by Myeloperoxidase (MPO)
PLACESS for your cats:
- Pseudomonas
- Listeria
- Aspergillus
- Candida
- E. Coli
- S. Aureus
- Serratia

22

Urease-positive

CHuck norris hates PUNKSS:
- Cryptococcus
- H. pylori
- Proteus
- Ureaplasma
- Nocardia
- Klebsiella
- S. epidermidis
- S. saprophyticus

23

IgA protease

Enzyme cleaving IgA--> colonize respiratory mucosa: SHiN
- S. pneumoniae
- H. influenza (B)
- Neisseria

** These can all take up naked DNA from environment as well= Transformation

24

Protein A

S. Aureus
- Binds Fc region of Ig--> no opsonization/phagocytosis

25

M Protein

Group A strep
- Prevents phagocytosis

26

Pigment-producing bacteria

Actinomyces Israelii= yellow (Israel= yellow sand)

S. Aureus= yellow (pus/gold)

Pseudomonas aeruginosa= blue/green (pyocyanin)

Serratia marcescens= red (maraschino cherry)

27

Novobicin

Used to ID catalase-positive, coagulase-negative staphylococci
- Staph Saprophyticus= resistant
- Staph Epidermis= sensitive

28

Optochin

used to ID catalase-negative alpha-hemolytic streptococci:
- Viridans= resistant
- Penumoniae= sensitive

29

Bacitracin

Used to ID Catalse-negative, beta-hemolytic streptococci:
- Agalactiae= resistant
- Pyogenes= sensitive

30

Alpha-hemolytic bacteria

Partial hemolysis; green ring around colonies
- Strep pneumo
- Strep viridans