GENERATIONS OF ANTIBIOTICS

Presented by: Tahmid FaisalLecturer, Dept. of Pharmacy

Stamford University Bangladesh

What is antibiotic?

Antibiotics are chemical compounds used to kill(Bactericidal) or inhibit(Bacteriostatic) the growth of infectious organisms (like Bacteria, protozoa)

How Different types of Antibiotics work ?

Generation of Antibiotics

Generation term comes only in case of Penicillins and Cephalosporins (Beta lactam antibiotics) and depending on their action on the cell wall of gram positive and gram negativebacteria they are classified by using terms ‘ Broad spectrum’ and ‘Narrow spectrum’ antibiotics.

Gram +ve Vs Gram –ve Bacteria

1st Generation Antibiotics

• Have a narrow spectrum of clinical use (this means there are only a few organisms that they are able to successfully treat with this class of penicillin)

• good for common gram-positive bacteria that cause ear and throat infections, venereal diseases of gonorrhea and syphilis, and staph infections due to Staphylococcus aureus that cause abscesses, endocarditis and pneumonia

• A very high number of the drugs in this group are resistant to organisms that produce penicillinase [Penicillinase is an enzyme that some bacteria are capable of producing. This enzyme is also called a beta-lactamase and it inactivates some of the penicillins.]

Examples

• Penicillin G and Penicillin V

• Cephalosporins:

Cephazolin

Cephalothin

Cephapirin

Cephalethin

Cephradin

Cephadroxin

2nd Generation Antibiotics

• Have an extended or Intermediate spectrumof clinical use (Some gram +ve and gram-ve).

• Work equally as well as penicillin G class plus effective against Escherichia coli, Proteus mirabilis and Haemophilus influenzae which are associated with urinary, respiratory and ear infections

• Not very effective against penicillinase-producing organisms

Examples

• Penicillin: Amoxicillin, Ampicillin

• Cephalosporin:

Cefuroxime

Cephamandole

Cephoxitin

Cephaclor

Cephrozil

Loracarbef

3rd Generation Antibiotics

• Third generation cephalosporin drugs are broad spectrum and the effective against both gram positive and gram negative bacteria. However their optimum activity is against gram negative bacteria.

• used in the treatment of serious urinary, respiratory and bacteremic infections due to gram-negative Pseudomonas aeruginosa and Proteus vulgaris

• not resistant to penicillinase-producing organisms

Examples

• Penicillin: carbenicillin and ticarcillin

• Cephalosporins:

Cephixime

Cephtriaxone

Cephotaxime

Cephtizoxime

Cephtazidime

4th Generation Antibiotics

• These are extended spectrum antibiotics. They are not resistant to Beta lactumase producing microorganisms.

• used for serious infections due to Pseudomonas aeruginosa, Proteus vulgaris, Klebsiella pneumoniae and Bacteroidesfragilis in combination with other antibiotics

• Examples: Cephipime

5th Generation Antibiotics

• Extended spectrum Antibiotics.

• Examples:

Cephtaroline : Pneumonia, skin and soft tissue infection

Cephtobiprole: Methicillin resistant Staphylococcus aureus.