Bacteria

Question 1

Bacterial size

Answer 1

0.1-10microns

Question 2

Gram negative

Answer 2

Thin cell wall&raquo_space;

outer membrane, thin peptidoglycan wall, inner membrane

Question 3

gram positive

Answer 3

Thick cell wall&raquo_space;

thick peptidoglycan wall, inner membrane

Question 4

bacterial cell wall

Answer 4

1. classification
2. semirigid –> peptidoglycan&raquo_space; prevents osmotic lysis
3. cell is hypertonic&raquo_space; wall prevents cell bursting&raquo_space;active transport to maintain hypertonicity

Question 5

transpeptidase

Answer 5

bacterial cell wall enzyme
catalyzes formation of peptidoglycan chain link
penicillin (& other antimicrobials) INHIBIT enzyme&raquo_space; inhibit cell wall formation

Question 6

Gram stain

Answer 6

1. crystal violet 2. gram’s iodine 3. alcohol wash 4. safranin stain
   Gram (+) stains PURPLE (crystal violet)
   Gram (-) stains RED (safranin)

Question 7

exceptions to gram stain

Answer 7

1. Mycobacteria tuberculosis - gram +&raquo_space;stains w/ acid fast (lipids in cell wall)
2. spirochetes - gram (-), too small, need DARKFIELD microscopy
3. Mycoplasma - no cell wall, simple cell membrane

Question 8

Clinical Correlation&raquo_space; Gram +

Answer 8

peptidoglycan layer doesn’t block diffusion of compounds, so we can damage cell membrane&raquo_space; kill bacterium

Question 9

Clinical Correlation&raquo_space; Gram -

Answer 9

outer lipopolysaccharide containing membrane, blocks passage of penicillin & other peptidoglycan attackers»need different coverage

Question 10

Metabolica characteristic: oxygen breakdown enzymes (3)

used for classification&raquo_space; possessed vs not possessed

Answer 10

molecular oxygen toxic unless broken down, survival mechanisms:

1. catalase- breaks down H2O2
2. peroxidase - breaks down H2O2
3. superoxide dismutase - breaks down superoxide radical

Question 11

metabolic characteristic : coagulase

used for classification

Answer 11

activating prothrombin» blood clots&raquo_space; clusters in culture

Question 12

metabolic characteristics : oxygen necessity

used for classification

Answer 12

1. obligate aerobe - needs O2 *all 3 enzymes
2. obligate anaerobe - killed by O2, gut flora, deep tissues
3. facultative anaerobe - can live in either enviro, prefer O2
4. aerotolerant anaerobe - less O2 requirements, fermentation&raquo_space; H2O2 is toxic to them

Question 13

virulence factors

Answer 13

1. flagella - mobility
2. pili (fimbriae)- adhesion/binding
3. capsules: protection from phagocytosis
4. endospores: resistance to environment, dormancy

Question 14

exotoxins

Answer 14

*proteins produced & excreted have affect on host>triggers immune response
Enterotoxins
neurotoxins
All Gram + (except Listeria monocytogenes)
Gram - : Vibrio cholera & Escherichia coli

Question 15

facultative intracellular organism

Answer 15

phagocytized by WBC&raquo_space; SURVIVE&raquo_space; escaping deadly chemicals&raquo_space; hideout b.c safe from antibodies while in macrophage

Question 16

Enterotoxins

Answer 16

infectious diarrhea
Vibrio cholera
E. coli
Campylobacter jejuni
Shigella dysenteriae

Question 17

Neurotoxins

Answer 17

affect neuro system

botulism & tetanus

Question 18

pyogenic exotoxins

Answer 18

stimulates release of cytokines

Cause rash, fever, toxic shock syndrom

Question 19

tissue invasive exotoxins

Answer 19

bacteria destroy & tunnel through tissue

Question 20

Endotoxins

Answer 20

ALL gram (-) & Listeria (gram +)
released from membrane w/ death of bacterium
mild to endotoxemia

Question 21

bacteremia

Answer 21

sepsis- systemic immune response
>>cytokines & prostaglandins 
*vasodilation
*Hypotension
*organ system dysfunction
septic shock

Question 22

Bacterial genetics: Transformation

Answer 22

DNA released during cell lysis > binds to cell wall of another bacterium > incorporated into the new bacterium

Question 23

Bacterial genetics: Transduction

Answer 23

bacteriophage (virus) infectes bacteria > carries bacterial DNA from one to another

Question 24

Bacterial genetics: conjugation

Answer 24

DNA transferred via cell to cell contact

Question 25

Bacterial genetics: transposons

Answer 25

mobile genetic elements (legs) carry genes for antibiotic resistance & virulence factors

Question 26

Diarrhea: no cell invasion

Answer 26

intestinal epithelial binding diarrhea from exotoxins (enterotoxins) cause electrolyte & fluid loss from cells & cell death Ex: E. coli, Vibrio cholera

Question 27

diarrhea: invasion of intestinal epithelial cells

Answer 27

toxins destroy cells, systemic response WBC positive stool test Ex: Shigella, Salmonella enteritidis

Question 28

Diarrhea: invasion of lymph nodes & bloodstream

Answer 28

fever, headache, WBC serum count, can lead to sepsis>>bloody diarrhea Ex: Salmonella typhi, Yersinia enterocolitica, Campylobacter jejuni

Question 29

paresthesias

Answer 29

tingling, tickling, prickling