ddt 16

Question 1

an antibiotic that hasn’t been used in clinics beadier but belonging to class of antibiotics

Answer 1

new antibiotics

Question 2

an antibiotics w mechanism of action never used against bacteria

Answer 2

novel antibiotics

Question 3

infections are mostly associated w

Answer 3

invasive medical devices and surgical procedures

Question 4

S.aureus produces

Answer 4

4 enzymes ( peniclin binding proteins PBP ) for cell wall biosynthesis

Question 5

PBP 1-4 can be modified by

Answer 5

b-lactam antibiotics leading to their inhibition and bacterial death

Question 6

MRSA produced —- which is not inhibited by— and can produce all functions of —-

Answer 6

• altered PBP. (PBP2a)
• b- lactam
• all 4 PBP of S aueures.

Question 7

the production of altered PBP is considered to be

Answer 7

recent resistance mechanism in gram +ve compared to the b-lactamase is ancient evolutionary

Question 8

Treatment of infection caused by MRSA

Answer 8

• antibiotics other than penicillin/ b- lactam
  ( almost 50% of mrsa strains r resistant to all but few antibiotics )
• vancomycin destroys mrsa and resistant bacteria
  ( first case was VRSA and there are 52 VRSA strains )

Question 9

novel antibiotics for mrsa treatments

Answer 9

• linezoid ( oxazolidinone )
• synercid ( combination of streptograms, quinupristin, dalfopristin )
• daptomycin ( lipopeptide )

Question 10

linezolid is a

Answer 10

oxazolidinone class of antibiotics

Question 11

linezoilds works for —- by inhibiting —- in only gram — bacteria

Answer 11

mrsa and VRE , inhibition of protein synthesis , gram +ve only

Question 12

intravenous treatment caused by VRE, staph. aureus, and strep. pyogen

Answer 12

Synercid by inhibiting protein synthesis both agents at same place in the ribosome

Question 13

—– when administered individually and —- when in combination

Answer 13

bacteriostatic, synerically and becomes bactericidal

Question 14

intravenous treatment of gram +ve infections by binding to cell membrane and causes depolarisation

Answer 14

daptomycin ( cubcin )
- it interrupts protein, dna and rna sythesis
- slow emerges of resistance in clinic

Question 15

patient being hostiblized for prolonged period of times and receiving multible course of antibiotics results in

Answer 15

antibiotic resistance

Question 16

enterococcus faecalis and enterococcus fascium are

Answer 16

more difficult to treat and higher incidence of resistance against vancomycin ( 15-20% of isolates )

Question 17

32 before emerges requires — genes mutation for resistance against vancomycin but 2-3 years against penicillin requires — mutation

Answer 17

5 genes , 1 gene

Question 18

vancomycin works by

Answer 18

inhibiting the cell wall beiosystheis and block the substrate while peciline blocks the enzyme

Question 19

is a glycopeptide antibiotic

Answer 19

vancomycin

Question 20

bacteria becomes resistant when

Answer 20

• loss of a single hydrogen bond = 1,000 folds drop in drug binding affinity ( from D-Ala to D- Lac )

Question 21

Clostridium difficile associated diseases ( CDAD)

Answer 21

• gram +ve
• requires anaerobic bacterium
• spores forming
• toxigenic strains: toxins A + B causes extensive damage to colonic mucosa

Question 22

—- causes major nosocomial diarrhoea

Answer 22

CDAD

Question 23

more than — produced — and — antibiotic treatment

Answer 23

90% after and during

Question 24

treatments of CDAD includes

Answer 24

1- medical therapy includes discontinuation of inciting antibiotic if possible
2- specific antibiotic treatment if persisent diarrhoea:
- metrazodiale at first line antibtioc agent
- vancomycin as alternate agent for 2nd line therapy
- both are taken orally

Question 25

20-25% of the patients will get --- of the symptoms once ------

Answer 25

recurrence, vancomycin. metronidazole withdrawal

Question 26

metronidazole is a

Answer 26

nitroaryl compound and exact mechanism is unknwon,

Question 27

how is the prodrug metronidazole is activated

Answer 27

activated by anaerobic organisms by reduction of nitro group to hydroxylamine group. During reduction it can damage bacterial cell components dna protein and mebrance

Question 28

the advantages of metronidazole as a first line therapy

Answer 28

- reserves vancomycin for MRSA - prevent selection if VRE

Question 29

when is vancomycin is used instead of metronidazole

Answer 29

- failure to reposed to metronidazole after 3-5 days - pregnancy , lactation - intolerance to metronidazole - critically ill patients - metronidazole- resistant infecting organisms

Question 30

gram --- is responsible for --- of HAI

Answer 30

gram -ve , 30%

Question 31

gram --- is responsible for --- ICU ( intensive care unit)

Answer 31

gram -ve , 70%

Question 32

the main HAI caused by gram -ve

Answer 32

- pneuminia: associated w mechanical ventilations - bloodstream infections: associated mostly from central vascular catheter and initial infections in the lungs, abdomen, and genitourinary tract - Urianry tract infections (UTI): associated mostly from urtheral cathetrization increased risk from 5-10% best management is to remove the catheter instead of antibiotic treatment

Question 33

many strains of gram -ve bacteria causing HAI are

Answer 33

-multi-drug resistant ( MDR , resist at least 3 different antibiotic classes ) - can have more than 1 resistance mechanism - requires the use of older antibiotic not used before bc toxicity issues lead to polymyxin

Question 34

some organisms resist all currently available antibiotic called

Answer 34

XDR : extreme drug resistance , including polymyxin ( acintobacter baemanni )

Question 35

the antibiotic carbapenems resistance is

Answer 35

carbapanese

Question 36

---- can inactivate all type of b lactam antibiotics and are not inhibited by inhibitors of b- lactamasse aka clavulenic acid which is a clinical challenge

Answer 36

carbapebenases

Question 37

treatment of HAI caused by gram -ve drug resistant

Answer 37

- gram -ve expressing ESBLS ( extended spectrum b- lactamase) : carbapene as meropenum - gram -ve expressibg carbapenemse : colistrin , trigcylin

Question 38

is a carbapenum b lactam antibiotic

Answer 38

meropenum

Question 39

meropenum structure similar to ----

Answer 39

penicillin - bicyclic structure , 1 b lactam ring , 5 membered ring - sulphur is not part of the 5-membered ring , its attached to a ring of functional side chain - carbon- carbon double bond in the 5-membered ring

Question 40

colistin ( polymyxin E)

Answer 40

- peptide antibiotic -polymyxin antibiotic - mixture of 2 cyclic peptide ( colistin A and b) produced by the fermentation of bacillus polymyxa - clinical use is perviously limited bc of nephrotoxity - reserved as last resort antibiotic of MDR gram -ve bacteria - binds to phosphate group in lipid on the cell cytoplasmic membrane and disturbs its integrity

Question 41

reserved as last resort antibiotic of MDR gram -ve bacteria

Answer 41

colistin

Question 42

tigecycline is

Answer 42

novel tetracycline class: glycylclines

Question 43

characterised by additioal glyclyamido substients

Answer 43

tigecyclin and it inhitbis bacteria protein sythesis and is broad spectrum antibiotic

Question 44

all novel antibiotics are effective against gram +ve but not -ve bc

Answer 44

gram -ve outer membrane is the main barrier

Question 45

number of novel classes of antibiotics for gram -ve bacteria under development

Answer 45

NONE LOL