Viro/bacteria exam 1

Question 1

Streptococci

Answer 1

Chains of spheres

e.g. Streptococcus (G+)

Question 2

Staphylococci

Answer 2

Grape-like/Irregular clusters Gram (+)

e.g. Staphylococcus

Question 3

Coccobacilius

Answer 3

Short and plump rods

ex. Haemophilus (G-)

Question 4

Fusiform

Answer 4

Rods with tapered ends

eg. fusobacterim (G-) often normal flor in oral cavity

Question 5

Diplococci

Answer 5

Paired spheres G (-)

e.g. Neisseriea

Question 6

coryneform

Answer 6

Club shaped rods

e.g. Corynebacterium (G+), diptheria

Question 7

Vibrio

Answer 7

Comma shaped, gently curved

eg Vibrio Cholera (G-),

Question 8

Spirochete

Answer 8

Spiral form

e.g. Treponema pallidum (G-), Syphilis

Question 9

Leptospira

Answer 9

Tightly wound spirals

e.g. Leptospira (G-)

Question 10

Borrelia

Answer 10

Very tightly wound spirals

e.g. Borrelia (G-)

Question 11

E. Coli

Answer 11

O157:H7

Question 12

Penicillin has 3 parts and what is its mode of action
-only active during the log phase (growth phase)
all end with “cillin”

Answer 12

Thiazolidine ring, beta-lactam ring and R group.

-The beta lactam ring interacts with transpeptidases (preventing the synthesis of peptidoglycan)

Question 13

Beta-lactamase inhibitors produced by bacteria to inhibit penicillin

Answer 13

-Clavulanate + amoxicillin = augmentin and clavulanate + ticarcillin = timentin (beta-lactmase inhibitors + penicillin)

Question 14

What 2 penicillin drugs are penicillinase resistant?

Answer 14

Methcillin and nafcillin

Question 15

Cephalosporins

-most are resistant to penicillinases

Answer 15

Similar to penicillins, less allergic reactions.
-Same mechanism of action (beta-lactam)
-can be administered IV or injection
- drugs begin with “cef” or “ceph”
Cephalosporins are broad spectrum and can cause super-infections

Question 15

Other beta-lactams and what do they do?

Answer 15

Imipenem and Aztreonam

They shut down the formation of NAG and NAM

Question 16

Isoniazid

Answer 16

Targets cell wall of tuberculosis.

-bacitracin also targets the cell wall

Question 17

Polymyxin

Answer 17

Narrow spectrum antibiotics, due to toxicity to kidney
-disrupts cell membrane function by inserting its tail into the membrane
polymyxin MIXES up the cell membrane

Question 18

Quinolones

Answer 18

Inhibit DNA topoisomerases (gyrases)

• Fluoroquinolones are broad “spectrum” and can inhibit both gram + and gram -
  e. gs Ciprofloxacin and norfloxacin (all the floxacins)

Question 19

Rifamycin

what is it used for TQ***

Answer 19

Inhibits DNA-dependent RNA polymerase by preventing RNA synthesis

• used for gram + rods and coccus TB and leprosy
• used for mycobacterial infections

Question 20

Metronidazole mode of action and who it works against

TQ

Answer 20

It uses a free radical (nitrogen) that damages bacterial DNA

-works against anaerobic bacteria

Question 21

What is the mode of action of Aminoglycosides, tetracylines, macrolides, chloramphenicol, clindamycin, streprogramin and oxazolidones?

Answer 21

Block protein synthesis by reacting with the ribosome-mRNA complex.

Question 22

Name the aminoglycosides

Answer 22

-end in cin (mins the floxacins)
Streptomycin,neomycin,kanamycin,gentamycin,toramycin,
amikacin,spectinomycin

Question 23

Name the tetracylines

Answer 23

end in cycline

-Tetracycline, doxycycline, minocycline

Question 24

Why is chloramphenicol not used in the U.S.?

Answer 24

Very toxic to human cells. Use is restricted to typhoid fever*

Question 25

Why is synercid?

Answer 25

A streptogramin. effective against staphylococcus and enterococcus and streptococcus

Question 26

What is linezolid?

Answer 26

It is an oxazolidone. used to treat MRSA and VRE the two most difficult pathogens

Question 27

Mode of action of sulfonamide and trimethoprim?

Answer 27

Inhibit folic acid synthesis. - Sulfonamides prevent PABA conversion to dihydrofolic acid - Trimethoprim inhibits dihydrofolic acid conversion to tetrahydrofolic acid - Communly used in combination against UTIs

Question 28

Which bacteria are penicillinase producing? | -drug resistantance

Answer 28

Staphylococcus aureus and neisseria gonorrhoeae (PPNG)

Question 29

How can a microbe become drug resistant?

Answer 29

1) drug inactivation (beta-lactamases inactivate penicillin) 2) decreased drug permeability or increased drug elimination 3) Change drug receptor (eg erythromycin alteration of the 50S ribosomal binding site) 4) Change in metabolic patters-develop alternate pathways or enzymes, eg folic acid synthesis

Question 30

Approaches to antimicrobial therapy

Answer 30

1. iron-scavenging capabilities (eg staphylococcus aureus) 2. riboswitches - inhibitors of translation 3. probiotics - prebiotics encourage growth of good bacteria 4. Iantibiotics -antibiotics (short peptides) made by bacteria to disrupt the cell wall/membrane

Question 31

What Abx are used for colitis?

Answer 31

Overgrowth of C. diff due to use of tetracyclines, clindamycin, and broad spectrum penicillins and cephalosporins.