Penicillin

Penicillin


PENICILLIN

MOA:

  • Are bactericidal antibiotics.
  • Bacterial cell wall synthesis completely depends on transpeptidase enzyme. 
  • Penicillin inhibits bacterial cell wall synthesis by blocking transpeptidase after binding to penicillin-binding protein (PBP).
CLASSIFICATION:

SOURCE

  •  NATURAL(Endrin plant Penicillin)
  • Penicillin-G 
  • Penicillin-V 

SEMI-SYNTHETIC 

  • Oxacillin 
  • Cloxacillin 
  • Dicloxacillin 
  • Methicillin 
  • Nafcillin 
  • Ampicillin 
  • Amoxycillin 
  • Carbenicillin 
  • Piperacillin 

ROUTE OF ADMINISTRATION:

  • ORAL 
  • Ampicillin 
  • Amoxycillin 
  • Penicillin-V 
  • Oxacillin 
  • Cloxacillin 
  • Dicloxacillin 

PARENTERAL Ticarcillin 

  • Penicillin-G 
  • Methicillin 
  • Nafcillin 
  • Carbenicillin 
  • Piperacillin(anti-pseudomonal drug) 
  • (Methicillin is Acid Labile penicillin)

SPECTRUM OF ACTIVITY:

NARROW SPECTRUM 

  • Methicillin 
  • Oxacillin 
  • Nafcillin 
  • Dicloxacillin 

BROAD SPECTRUM 

  • Ampicillin 
  • Amoxycillin 

INTERMEDIATE SPECTRUM 

  • Penicillin-G 
  • Penicillin-V 

EXTENDED SPECTRUM 

  • Carbenicillin 
  • Ticarcillin 
  • Piperacillin 
  • Mezlocillin 

RESISTANCE TO ENZYME:

RESISTANCE TO β-LACTAMASE 

  • Methicillin 
  • Nafcillin 
  • Oxacillin 
  • Cloxacillin 
  • Dicloxacillin 

NON- RESISTANCE TO β-LACTAMASE 

  • Penicillin-G 
  • Penicillin-V 
  • Ampicillin 
  • Amoxycillin 
  • Carbenicillin 

RESISTANCE TO ACIDS:

ACID STABLE 

  • Penicillin-V 
  • Ampicillin 
  • Amoxycillin 
  • Oxacillin 
  • Cloxacillin 
  • Dicloxacillin 

ACID UNSTABLE 

  • Penicillin-G 
  • Methicillin 
  • Nafcillin 
  • Carbenicillin 
  • Piperacillin 
  • Ticarcillin

USES:

Streptococcal Infections: 

  • Pharyngitis, 
  • Otitis Media, 
  • Scarlet Fever  
  • Rheumatic Fever (1.2 MU every 4 weeks of benzathine penicillin)
  • Subacute Bacterial Endocarditis 
  • Treatment of spreading streptococcal cellulitis

 Pneumococcal Infections: 

  • Lobar Pneumonia.
  • Antipseudomonal penicillins includes carboxypenicillin & ureidopenicillins.

Meningococcal Infections: 

  • Meningitis 

Gonococcal Infections:

  •  Ophthalmia Neonatorum 
  • Syphilis(2.4 MU single i.m. of benzylpenicillin )Treatment for clostridial myonecrosis

 Leptospirosis:

  • Presence of fever, jaundice and renal failure in a sewage worker (contact with rat urine) suggests a diagnosis of Wen syndrome or Icterohemorrhageic fever caused by leptospirae.
  • Penicillin G (intravenously) is recommended agent.
  •  Diphtheria 
  • Tetanus 
  • Anthrax 
  • Quinsy 
  • Treatment of contaminated wound in Gas Gangrene 
  • Drug of choice for Treponema Pallidum
  • Actinomycosis: For thoracic actinomycosis
  • Enterococcus faecalis: When isolated in blood, requires synergistic activity of penicillin plus an aminoglycoside for appropriate therapy.
  • Rat bite fever 
  • Prophylaxis 
  • Rheumatic Fever 
  • Bacterial Endocarditis
  • Agranulocytosis

ADVERSE EFFECT:

Hypersensitivity- 

  •  rash, itching, urticaria, fever 
  • wheezing, angioneurotic edema, serum sickness, exfoliative dermatitis (less common)
  • Anaphylaxis (rare, but fatal)

 Superinfections 

  •  Bowel, respiratory and cutaneous microflora can undergo changes
  • Jarisch- Herxheimer Reaction

 Local irritation 

  • Pain at injection site 
  • Thrombophlebitis 

 Neurotoxicity 

  •  Mental confusion, muscular twitching, convulsions, coma

 Bleeding 

  • Due to interference of platelet function 
  •  Intrathecal PnG injections (not recommended)
  • Arachnoiditis, degenerative changes in spinal cord 
  • Accidental IV procaine penicillin injection 
  • CNS stimulation, hallucinations, convulsions.

PENICILLIN RESISTANCE

Beta-lactamase (Penicillinase) Production

  • Most common mechanism
  • Both gram-positive & gram-negative organism produces beta-lactamase which opens beta-lactam ring inactivating antibiotic.

Altered penicillin-binding protein (PBP)

  • Bacteria alters penicillin-binding protein structure, transpeptidase.
  • Hence, prevents penicillin-binding site.
  • Eg: In case of MRSA.
Exam Question
 
  • Treatment of S. aureus infection with penicillin is often complicated by the production of penicillinase by S. aureus
  • Carbenicillin is NON- RESISTANCE TO β-LACTAMASE
  • Syphilis, Anthrax and Bacterial meningitis are therapeutic uses of penicillin G
  • Antipseudomonal penicillins include the carboxypenicillin and the ureidopenicillins.
  • Penicillin Binding Proteins (PBPs) are essential for cell wall synthesis
  • Penicillin Binding Proteins (PBPs) act as carboxypeptidases and transpeptidases
  • Alteration in PBP’s is the primary bases of resistance in MRSA
  • β- Lactamase production is the most common mechanism of resistance to Penicillin 
  • Alteration in permeability/penetration of antibiotic causes resistance only in Gram-negative bacteria
  • β-Lactamase production causes resistance in both Gram-positive and Gram-negative bacteria
  • Penicillin would be LEAST effective in treating Mycoplasma pneumonia
  • Enterococcus faecalis when isolated in the blood, requires the synergistic activity of penicillin plus an aminoglycoside for appropriate therapy
  • Plant penicillin is Endrin
  • Penicillins inhibits cell wall synthesis 
  • Methicillin is Acid Labile penicillin
  • Penicillinase-resistant penicillin Methicillin 
  • The dosage of benzylpenicillin in the treatment of primary syphilis is 2.4 MU single i.m.
  • Treatment for clostridial myonecrosis is Penicillins 
  • Penicillin is Drug of choice for Treponema Pallidum
  • Penicillin is Drug of choice for thoracic actinomycosis
  • Penicillin  in high doses can cause convulsions
  • The clinical presentation of fever, altered sensorium and purpuric rashes, is highly suggestive of meningococcal meningitis is treated with Penicillin  
  • TOC for penicillin-resistant gonorrhoea Ceftriaxone
  • Presence of fever, jaundice and renal failure in a sewage worker (contact with rat urine) suggests a diagnosis of Wen syndrome or Icterohemorrhageic fever caused by leptospirae. Penicillin G (intravenously) is the recommended agent.
  • Treatment of spreading streptococcal cellulitis is Penicillin 
  • Treatment of contaminated wound in Gas Gangrene is Penicillin 
  • Rapidly spreading infection of the external auditory canal with the involvement of the bone and presence of granulation tissue point towards malignant otitis externa  treated with Penicillin 
  • Penicillin is used in the treatment of quinsy 
  • Piperacillin is an anti-pseudomonal drug of penicillin-class
  • Dose and duration of benzathine penicillin for prophylaxis of rheumatic fever is 1.2 MU every 4 weeks
Don’t Forget to Solve all the previous Year Question asked on Penicillin

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