Infections - Antibiotics

Question 1

Difference between Antimicrobials & Antibacterials ?

Answer 1

Antimicrobials = Include antibiotics,antivirals, antifungals, Antiprotozoals

Antibactierals = Only target Bacteria

Question 2

Antimicrobial resistance ?

Answer 2

Loss of effectiveness of anti- Infective medicine

Question 3

Primary goal of Antimicrobial stewardship ?

Answer 3

Promote & monitor Judicious use of Antimicrobials to PRESERVE effectiveness

Question 4

Gram staining ?

Answer 4

Lab technique used to differentiate Bacteria into 2 groups based on Cell wall structure

Question 5

Summary of Gram staining Process

Answer 5

Crystal Violet: Stains both types purple.
Iodine: Fixes crystal violet stain into cell wall.
Decolorization (Alcohol): Removes stain from Gram-negative bacteria but not from Gram-positive bacteria.
Safranin (Counterstain): Stains Gram-negative bacteria pink/red, while Gram-positive bacteria stay purple.

Question 6

Two Gram positive Bacteira associated with Respiratory and Skin conditions

Answer 6

streptococcus and Strephylcoccus

Question 7

Which Bacteria commonly associated with UTI

Answer 7

E. coli

Question 8

Common Pathogens involved in community acquired Pneumonia ?

Answer 8

Streptococcus Pneumoniae (Positive), Haemophillus Influenzae (Negative)

Question 9

Two major factors of Antibiotic efficiacy ?

Answer 9

Drug conc, Time at binding site

Question 10

Four classes of Antibiotics (examples) & Mechanism of action

Answer 10

Beta Lactam (Penicillin, Amoxicillin) = Inhibit bacterial cell wall synthesis
Aminoglycosides (Gentamicin) = Inhibit Protein synthesis. Binds to 30s Ribsosome causing errors in protein chain
Quinolones ( Ciproflaxcin ) Interfere with DNA replication
Tetracyclines (Doxycycline) Inhibit Protein synthesis. Block attachment of Aminoacyl-tRNA to RIBOSOME

Question 11

Side effects of Aminoglycosides ?

Answer 11

Nephrotoxicity (renal), Neuromuscular effects, Ototoxicity

Question 12

Four mechanisms which Bacteria develop Antibacterial resistance ?

Answer 12

1. Penetration resistance ( Bacteria prevent antibiotics enter cells)
2. Efflux pumps (Act like recycling machines. Pump out harmful substances e.g antibiotics
3. Enzymatic Hydrolysis ( Beta Lactamases) Break down structure of Antibiotic. Break down Beta lactam ring in antibiotic making it INACTIVE
4. Mutation of Binding sites (Alter binding site)

Question 13

Patient factors to be considered before prescribing Antibiotics ?

Answer 13

Alleriges, renal/Hepatic funciton, Pregnancy, age, PRIOR antibiotic use

Question 14

When should IV antibiotics be reviewed ?

Answer 14

Within 48 Hours, with consideration for stepping down to ORAL

Question 15

Difference between Broad and Narrow spectrum Antibiotic ?

Answer 15

Broad = Effective against different types of Bacteria. E.g Penicillin (Amoxicillin) Quinolone (Ciproflaxcin)
Narrow = Effective against limited no. of Bacteria e.g Penicillin (Flucloxacillin)

Question 16

: Why should broad-spectrum antibiotics be avoided when narrow-spectrum ones are effective?

Answer 16

broad-spectrum antibiotics can kill wider range of bacteria, including Beneficial bacteria. Can lead to INCREASED antibiotic resistance + Clostridium difficile infection

Question 17

When might a NO- Antibiotic strategy be appropriate ?

Answer 17

Actue SELF-LIMITING upper respiratory tract infections. e.g Common cold/sore throat. Caused by VIRUSES, therefore antibiotics NOT effective. Can resolve itself

Question 18

What is the primary aim of antibiotics?

Answer 18

To KILL pathogenic bacteria, while causing NO harm to human tissue

Question 19

What is Colostrium difficle infection ?

Answer 19

Bacterial infection of Colon. occurs after use of Antibiotics

Question 20

What factors increase risk of Colistrium difficle infection ?

Answer 20

1. Broad spectrum Antibiotic use
2. Multiple antibiotic exposures
3. PPI use

Question 21

What are some Principles of Antimicrobial stewardship

Answer 21

1. Initiate effective therapy & Review regularly
2. Promote Narrow spectrum Antibiotics where appropriate
3. Monitor + Adjust based on patient response

Question 22

What is the minimum Inhibitory Concentration (MIC) of Antibiotics

Answer 22

LOWEST conc of Antibiotic that Inhibits visible growth of Bacteria

Question 23

What is the minimum Bacterial Concentration (MBC) of Antibiotics

Answer 23

MBC is the lowest concentration of an antibiotic that kills the bacteria

Question 24

What Antibiotic associated with ‘Red man Syndrome’

Answer 24

Vancomycin(Glycopeptide). Flushing/itching reaction due to Rapid infusion of IV Vancomycin

Question 25

Which Antibiotics CONTRAINDICATED for children under 12 ?

Answer 25

Tetracyclines- Can affect bone growth + discolouration of teeth

Question 26

What interaction occurs between metronidazole and alcohol?

Answer 26

Severe nausea + vomiting. Similar to drug disulfiram - used to stop Alcoholics

Question 27

What should be monitored during Long term Nitrofurantoin treatment?

Answer 27

Renal function (Avoid if below eGFR <45mL/min) Liver function

Question 29

What Antibacterial effect does Beta Lactamase inhibitors have ?

Answer 29

None. Instead BLOCKS action of Beta Lactamase enzymes produced by Bacteria. Allowing antibiotic to remain effective.

Question 30

Arrange these 4 Penicillins in order or Increasing spectrum. Amoxicillin. Penicillin G. Flucloxacillin. Piperacillin + Tazobactam

Answer 30

In order from Narrowest to Broadest. Penicillin G, Flucloxacillin, Amoxicillin, Piperacillin + Tazobactam

Question 31

MOA of Beta lactam antibiotics

Answer 31

Inhibits cell wall synthesis by BINDING to Transpeptidase enzyme. Prevents cross linking of Glysosidic chains leadingto cell death

Question 32

What is the MBC/MIC ratio, and what does it indicate?

Answer 32

Ratio used to determine whether an antibiotic is bactericidal or bacteriostatic. If the MBC is four times greater than the MIC, it indicates bacteriostatic activity; otherwise, it indicates bactericidal activity.

Question 33

Why are Mycoplasma spp. resistant to beta-lactam antibiotics?

Answer 33

Mycoplasma spp. LACK cell wall, which is target of beta-lactam antibiotics (Penicillin). Since these bacteria lack peptidoglycan wall, the MOA of beta-lactams is ineffective against them.

Question 34

What are two main mechanisms by which bacteria develop resistance to Penicillin G.

Answer 34

1. Beta-lactamase production- Bacteria e.g Staphylococcus aureus produce beta-lactamase enzymes that hydrolyze beta-lactam ring of Penicillin G, inactivating it. 2. Alteration of Binding site- presence of mecA gene = less susceptible to Penicillin G

Question 35

What's the issue of designing antibiotics resistant to Beta lactamase ?

Answer 35

The Steric shield must be large enough to FIGHT Lactamase enzyme but not so large that it prevents binding to the target enzyme.

Question 36

Which is more reactive with transpeptidase, penicillin or cephalosporin, why?

Answer 36

Penicillins MORE reactive with transpeptidase because their five-membered ring creates more strain on Beta-lactam ring, making it more reactive. Cephalosporins, with six-membered ring, are less reactive due to reduced strain.