Penicillins

Question 1

Beta-lactam antibiotics

Answer 1

1. Penicillins
2. Cephalosporins
3. Lactamase-inhibitors
4. Monobactams
5. Carbapenems

Question 2

What do Penicillin work on

Answer 2

binds to PBP (penicillin binding protein) in Transpeptidase and Carboxypeptidase which are responisble for the cell wall cross-linking of transpeptide bonds (N-acetyl-muramic acid + N-acetyl-glucoseamine chain) .
effects only dividing cells! (= cell wall synthesis) -> bacteriolysis

Question 3

Penicillin mode of action

Answer 3

Bactericidal
time dependant (3-5 days)
+ post-antibiotic effect

Question 4

Resistancy

Answer 4

Types:

i. Beta-Lactamase production:
1. Staphyloccoci sp - Gram + are the most sensitive as they usually don’t produce B-lactamse- except for Staph
2. Pseudomonas aureginosa - Gram - are more resistant produce B-lactamase, especially P.aureginosa)
3. Mycobacteria, Brucella , Chlamydia- Acid fast bacteria are the most resistant.
4. Mycoplasma (no cell wall)
ii. PBP gene mutation (e.g MRSA+MRSP-methicillin resistant Staphylococcus aureus+ Staph. pseudointermedius)

Question 5

Penicillin main indications

Answer 5

Gram positive bacteria:
Bacillus, Clostridium, streptococcus, Erysipelothrix, Cornybacterium, Arcanobacterium pyogenes , Actinomyces, Listeria .

*NOT in mycobacterium, Staphyloccocus, enterococcus.

Question 6

Penicillin spectrum classes

Answer 6

1. Narrow spectrum penicillins: G+ , destroyed by beta-lactamase.
2. Penicillinase stable penicillins: G+ , not destroyed by beta-lactamse
3. Broad spectrum penicillins (aminopenicillins): both G+ and G- ,amoxicillin . NOT pseudomonas
4. Penicillins acting against Pseudomonas spp.

Question 7

Narrow spectrum penicillins - drug names

Answer 7

IM,SC

1. Benzylpenicillin–Na, K: water soluble, 2-4h
2. Benzylpenicillin–procaine: slow, 24h
3. Benzylpenicillin – benzathine: very slow 72-96h
4. Phenoxymethyl-penicillin: PO

Question 8

Narrow spectrum penicillins - Bacteria

Answer 8

1. Most of the Gram+ bacteria
2. Gram – fastidious organisms : pasturella, histophilus, haemophilus and mannhemia
3. Leptospira, Borrelia spp.

Question 9

Narrow spectrum penicillins - pharmacokinetics

Answer 9

Hydrophilic drug,cannot enter the cell (not against IC bacteria), cannot cross BBB, excretion via kidneys unchanged (good for UTI)
short HL
no liver toxicity
*PO: phenoxymethyl-penicillin

Question 10

Narrow spectrum penicillins - Side effects

Answer 10

almost non-toxic , allergies , dysbacteriosis in monogastric herbivores (Eq, rabbit , herbivore rodents)- stop if diarrhea
*Procaine-penicillin - local anesthetic, most toxic, ataxia, termour, piglets are sensitive

Question 11

Narrow spectrum penicillins - indications

Answer 11

drug of choice in:

i. Swine erysipelas
ii. Anthrax
iii. Tetanus
iv. Clostridium perforinges
v. Streptococcosis (eq: strangle, SA: skin, laryngitis , Ru: mastitis , su: septicaemia)
vi. (mastitis,metritis)

Question 12

Penicillinase stable penicillins - bacteria

Answer 12

• Only G+ (bacillus,clostridium , sterptoccocus, erysipelothrix, cornybacterium, aracnobaterium pyogenes, actinomyces,listeria)
• staphyloccocus is resistant.
• does not effect mycobacterium and enterococcus

Question 13

Penicillinase stable penicillins - drug names

Answer 13

1. Oxacillin (0Cl)
2. Cloxacillin (1 Cl)
3. Dicloxacillin (2Cl)
4. Flucloxacillin (Cl- and Chlorine, best distribution)
5. Methicillin - not used (acid sensitive - destroyed by stomach)

Question 14

Penicillinase stable penicillins -Indications

Answer 14

i. Mastitis (bo) - Intramammary infusion (staph+strep mostly)
ii. (Dermatitis (ca) - non reliable oral dist.)

Question 15

Broad spectrum penicillins - Bacteria

Answer 15

1. All G+ except for mycobacterium
2. G- :
   i. Fastidius: Pasturella,Haemophillus, actinobacillus, Manheimia
   ii. Enterobacteriaceae: E. coli , salmonella, klebsiella
   iii. Anaerobic bacteria: Proteus ,baceriodes , fusobacterium (oral cavity, bite wounds)
   iv. Leptospira and Borrelia

Question 16

Broad spectrum penicillins - Drugs + Pharmcokinetics

Answer 16

1. Ampicillin: weak-moderate PO, reduces feed, IV (-Na,-Trihydrate)
   * combination: SULBACTAM
2. Amoxicillin: good-excellent PO, does not reduce feed, IV (-Na, -Trihydrate)
   * combination: CLAVULANIC ACID
3. Bacampicillin
4. Pivampicillin

Question 17

Broad spectrum penicillins- Amoxicillin indications

Answer 17

1. UTI: Amoxicillin is the 1st choice (E.coli)
2. GI - only in Clostridium perfringes
3. Dermatitis (Staph), in combination with Calvulanic acid
4. Lyme disease (borrelia)
5. Bite wounds + oral infections: anaerobic G- , + calvulanic acid
6. Osteomyelitis - staph , + calvulanic acid

Question 18

Penicillins acting against Pseudomonas spp

Answer 18

• Best and most expensive
• used in life threatening anaerobic infections (intestinal perforation->peritonitis)

1. Piperacillin (+ Tazobactam): IV,IM
2. Ticarcillin (+CA): PO
3. (Carbenicillin)

Question 19

Beta-lactones inhibitors: Salbactam (+ampicillin), Tazobactam (+piperacillin) and Calvulanic acid (+amoxicillin)

Answer 19

suicide inhibitors to be destroyed by B-lactamase instead of the antibiotic.
*works also against G+ Staphylococcus

Question 20

Monobactams

Answer 20

Excellent activity against UTI

1. Azotreonam - parenteral
2. Tigemonam (PO)

Question 21

Carbapenems

Answer 21

Last resort antibiotics!! IV,IM, highly active against all important known pathogenic bacteria!!

1. Imipenem (+Cilastatin): metabolized by dihydropeptidase in the kidneys
2. Meropenem