This document discusses antibiotics including their definition, types, mechanisms of action, spectrum of activity, and factors affecting their use. It describes different classes of antibiotics like sulfonamides, quinolones, beta-lactams, and others. It covers topics like mechanisms of antibiotic action, types of microbes certain antibiotics target, factors influencing antibiotic choice, and combination antibiotic therapy.

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These are substances produced by
microorganisms, chemical synthesis, &
natural substance, which selectively suppress
the growth of or kill other microorganisms at
low concentrations…..

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Bacteriostatic agent:
inhibit the growth of bacteria..
Bacteriocidal agent:
directly kill bacteria…

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A) chemical structure
B) mechanism of action
C) type of organisms against which primarily
active
D) spectrum of activity
E) type of action
F) antibiotic are obtained from…..

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Sulfonamides and related drugs: sulfadiazine,
sulfones, dapsone
Diaminopyrimidines: trimethoprim,
pyrimethamine.
Quinolones: nalidixic acid, norfloxacin,
ciprofloxacin, gatifloxacin etc
Beta lactam antibiotics: penicilline,
cephalosporins

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Nitrobenzene derivatives :chloramphenicol
Aminoglycosides: streptomycin, gentamycin,
amikacin, neomycin.
Macrolide: erythromycin clarithromycin,
azithromycin.
Lincosamine: lincosamycin; clindamycin
Glycopeptide: venconamycin
Oxazolidinone : linezolid
Polypeptide:polymyxin b
Nitrofuran : nitrofurantoin ,

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Nitroimidazoles: metronidazole, tinidazole
Nicotinic acid: isoniazid, pyrazinamide,
Polyene : nystatin, amphotericin –b
Azole derivatives:
Others: rifampin , cycloserin, ethambutol, etc

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1) inhibit cell wall synthesis
2) cause leakage from cell membrane
3) inhibit protein synthesis
4) cause misreading f m RNA code and affect
permeability
5) inhibit DNA gyrase
6) interfere DNA fuction, syntesis
7) interfere in metabolism

9. 1) antibacterial : penicillins ,
aminoglycosides,
Erythromycin
 2) Antifungal : griseofulvin, amphotericin b,
ketoconazole etc
 3)Antiviral : acyclovir , zidovudine,
amantadine.
 4) antiprotozol : chloroquine,
metronidazole….
 5) anthelmintic: mebendazole
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A)Narrow spectrum: penicilline g,
streptomycin, erythromycin,
B)broad spectrum: tetracyclines,
chloramphenicol

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A) fungi: penicilline, cephalosporin ,
griseofulvin
B) bacteria: polymycin b
C) actinomycetes: macrolides, polyenes,
aminoglycosides, tetracyclines,
chloramphenicol…..

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1) toxicity
A) local irritancy.
B) systemic toxicity
2) hypersensitivity reaction
3) drug resistance

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A) drug tolerant:
B) drug destroying
C) drug impermeable
D) cross resistance

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4) Super infection ( suprainfection)
5) nutritional deficiencies
6) masking of infection

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1) patient factors
Age
Renal and hepatic function
Local factors
Drug allergy
Impaired host defence
Pregnancy
Genetic factors

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Clinical diagnosis itself directs choice of the
AMA
A good guess can be made
Choice to be based on bacteriological
examination

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Spectrum of activity
Type of activity
Sensitivity of the organism
Relative toxicity
Pharmacokinetics profile
Route of administration
Evidence of clinical efficacy
cost

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To achived synergism:eg
Penicilline+ sulfonamide
Penicilline+ gentamycin
Steptomycin + tetracycline
Rifampin+ dapsone
To reduced severity or incidence.:
Amphotericin b+ rifampin…

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To broaden the spectrum of antimicrobial
action
Treatment of mixed infection
Initial treatment of severe infection
Topicallly

20. Thank
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