General and Gram (+) Bacteria Flashcards
(36 cards)
1
Q
Structure
A
- Cell walls
- Nucleoid
- Plasma membrane
- Capsule (some): made of carbs
- Flagella
- Plasmids (some)
- Circular chromosomes
2
Q
Classification
A
1. Shape A. Cocci B. Bacilli C. Spiral 2. Cell wall (gram staining) A. Amino acids and carbs B. Peptidoglycan 3. Growth characteristics A. Oxygen requirements 4. Molecular A. PCR B. Antigen detection C. Mass spectroscopy
3
Q
Gram stain
A
- Fixation (heat)
- Crystal violet -> everything purple
- Iodine: fix stain
- Decolorize: acid alcohol
A. (+) purple
B. (-) clear - Counter saffranin-> (-) pink
4
Q
Cell wall synthesis antibiotics
A
- Beta lactase
- Penicillins
- Cephalosporins
- Carbapenems
- Monoabactams
- Glycopeptides
5
Q
Folate synthesis antibiotics
A
- Sulfonamides
- Trimethoprim
* synergistic
6
Q
Protein synthesis antibiotics
A
- 50S subunit
A. Macrolide
B. Oxazolidinones
C. Chlorampnthenicol - 30S subunit
A. Aminoglycosides
B. Tetracyclines
*50S MOC AT 30S
7
Q
RNA Polymerase antibiotics
A
- Rifamycins
8
Q
Cell membrane disruptor antibiotics
A
Polymyxins
9
Q
Nuclei acid synthesis
A
- Quinolones
* inhibits DNA gyrase
10
Q
Non-selective or differential
A
Only used when don’t know what you’re dealing with
1. Allows anything to grow
11
Q
Blood agar
A
- Non-selective
- Differential (hemolysis)
A. Alpha - partial
B. Beta- complete
C. Gamma - none
12
Q
Chocolate agar
A
- Non-selective
* H. Influenzae needs lysed RBC - Non-differential
13
Q
MacConkey agar
A
- Selective for gram (-)
2. Differential for lactose fermentation
14
Q
Thayer-Martin (VCN) agar
A
- Selective for Neisseria meningitis
- Chocolate agar supplemented
A. Vancomycin
B. Colistin
C. Nystatin
15
Q
Lowenstein-Jenson agar
A
- Mal. Green
2. Mycobacteria
16
Q
Virulence factors
A
1. Direct pathogenesis A. Secreted toxins and enzymes B. Capsule: escape phagocytosis C. Cell surface structures: add to virulence 2. Indirect pathogenesis A. Siderophores: bind and transport Fe in microbes B. Secretion machinery C. Catalase D. Regulatory factor
17
Q
Gram (+) cocci
A
1. Staphylococci A. S. Aureus B. Other staph 2. Streptococci A. Pneumonia B. Pyogenes C. Agalactaie (group B) D. S. Viridans (group B)
18
Q
Gram (+) bacilli
A
- Clostridia- gangrene
- Bacillus
A. Anthracis
B. Cereus - Listeria
A. Monocytogenes (raw dairy) - Erysipelothrix
A. Rhusiopathiae - Corynebacterium
A. Diptheriae - Mycobacteria
19
Q
Anaerobic gram (+) cocci
A
- Normal flora
- Examples:
A. Anaerococcus
B. Atopobium
C. Finegoldia
D. Micromonas
E. Peptoniphulus
F. Peptostrptococcus
G. Schleiferella
20
Q
Anaerobic gram (+) bacilli
A
- Actinomyces
- Bifidobacterium
- Eubacteria
- Lactobacillus
- Mobiluncus
- Propionibacterium
21
Q
Lab studies gram (+)
A
- CBC
- Electrolytes
- Blood cultures (systemic infections)
- Pro-calcitonin levels
- Echocardiogram if endocarditis suspected
- Joint aspiration if septic joint is suspected
22
Q
Gram (+) infection presentation
A
- Bulbous impetigo
- Draining sinus tract
- Erythema
- Fever
- Murmur (endocarditis)
- Petechiae (toxic shock syndrome)
- Superficial abcess
- Warmth
23
Q
Gram (+) culture tests
A
1. Catalase test A. (+) = oxidation 1. Staphylococci B. (-) = no oxidation 1. Streptococci
2. Coagulase test: different S. Aureus vs. other staph species (CNS) A. (+) = fibrin clot 1. S. Aureus B. (-) = no clot 1. S. Epidermidis 2. S. Saprophyticus
24
Q
S. Aureus diseases
A
- Can colonize and become normal flora (30%) -> inc. risk infection
- Superficial lesions - wound infection
- Toxinoses: caused by toxins bacteria produce
A. Food poisoning
B. Scalded skin syndrome
C. Toxic shock syndrome - Systemic and life-threatening conditions
A. Endocarditis
B. Osteomyelitis
C. Pneumonia
D. Brain abcesses
E. Meningitis
F. Bacteremia - Virulence factors
A. Adhesions
B. Exoproteins (exotoxins)
25
Antibiotic susceptibility testing
1. Broth dilution: test min concentration of cause effects
A. Labor intensive
2. Antimicrobial gradient
3. Disc diffusion
26
Antibiotic resistance mechanisms
1. Permeability change in cell wall - restrict access
2. Active effluent antibiotic
3. Enzymatic modification of antibiotic
4. Antibiotic degradation
5. Alternate metabolic pathway
6. Antibiotic target modification
7. Overproduction of target enzyme
27
Acquisition of resistance genes
1. Chromosomal mutations: targeted gene not susceptible
2. Transformation: piece resistant DNA taken into pathogen
3. Conjugation: DNA (usually plasmids) transferred thru pills
4. Transduction: virus inserts DNA/RNA
A. 1st S. Aureus resistance- phage type 80/81 strains (penicillin resistant)
5. SCC mec (staphylococcal chromosome cosseted mec)
28
Biofilms
```
1. Lifecycle
A. Single bacteria on surface
B. Cells aggregate and attach
C. Growth + division -> biofilm
D. Mature biofilm
E. Part disperses to start new colony
2. Aggregates of bacteria
3. Extreme resistance to antibiotics
4. Resist phagocytosis
5. Gene regulation
6. Staph. Often form them
```
29
Streptococcus classification
1. Colony morphology
2. Hemolysis
A. Beta - complete
B. Alpha - partial
C. Gamma - none
3. Biochemical rxns
4. Serologic specificity
A. Antigenic differ in cell wall carbs
1. Groups A-V
30
Strep pygenes
```
Group A
1. Diseases:
A. Pharyngitis (strep throat)
B. Scarlet fever
C. Impetigo
D. Cellulitis
E. Erysipelas
2. Invasive infections:
A. Necrotizing fasciitis
B. Myositis
C. Strep. Toxic shock
3. Immune-mediated sequelae
A. Acute rheumatic fever
B. Acute glomerulonephritis
4. Alpha and beta hemolytic
```
31
Strep pneumoniae
1. Pneumonia
2. Meningitis
3. Occult bacteremia
4. Characteristics
A. Alpha hemolytic
32
Strep agalactiae
```
1. Neonates
A. Meningitis
B. Neonatal sepsis
C. Pneumonia
2. Adults
A. Vaginitis
B. Puerperal fever
C. UTI
D. Skin infection
E. Endocarditis
```
33
Viridians streptococci
Endocarditis
34
Enterococcus
1. UTI
| 2. Biliary tract infection
35
Spore forming gram (+) bacilli
```
Inert when conditions are bad
1. Closteridia
2. Bacillus
A. Anthracis
B. Cereus
*anaerobic
```
36
Anaerobes
```
1. O2 toxic: absence of enzyme
A. Catalase
B. Superoxide dismutase
C. Peroxidase
2. Characteristics
A. Fastidious organisms
B. Difficult to grow
C. Required proper collection and culture methods
D. Dx requires clinical suspicion
3. Types:
A. Obligate
1. Energy thru fermentation
2. Use organic cmpds as terminal e- acceptor
B. Faculatative: can tolerate O2
4. Examples:
A. Clostridium perfringens: causes gas gangrene or soft tissue infections
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