This PDF deals with important guidelines, with respect to usage of antibiotics. This PDF outlines the important strategies involved while using antibiotics, and important factors involving antibiotic selection.

1. RATIONAL USE OF ANTIBIOTICS: A BRIEF
SUMMARY OF WHAT GUIDELINES SAY
- Dr. Vishnu R. Nair
WHAT IS AN ANTIBIOTIC?
“An antibiotic is a chemical, derived from microbes or synthetically, that has the
potential to either INHIBIT the growth of susceptible organism
(BACTERIOSTATIC EFFECT), or KILL them (BACTERICIDAL EFFECT),
at low concentrations.”
INDICATIONS FOR ANTIBIOTIC THERAPY: WHAT DO
GUIDELINES SAY?
Basically  antibiotics can be administered to patients, on 3 different conditions:
1. Definitive therapy:
- Indicated for proven bacterial infections, in which the culprit microbe is
identified, by means of:
 Staining of secretions/ fluids/ exudates
 Culturing & sensitivity testing
 Serological tests
- Based on test reports  administer:
 Narrow spectrum
 Least toxic antibiotic
 Cheap

2. 2. Empirical therapy:
- Indication is restricted to CRITICAL CASES ONLY
- CRITICAL CASE: Clinical situation, where time is insufficient for
bacterial test diagnosis, & strong doubt/affirmation of bacterial
infection exists
- Critical cases may include:
 Septic shock
 Immunocompromised patients, with severe systemic infections
 High temperatures
 Neutrophilic leukocytosis
 High ESR, etc.
 In such cases  focus on broad-spectrum antibiotics, aiming at
covering maximum probable infective agents.
3. Prophylactic therapy:
 Indicated for “susceptible patients, with the intention of preventing
specific infections, that can cause detrimental effects”
 Prophylactic therapy for antibiotics includes situations like:
- Anti-rheumatic prophylaxis
- Prophylactic use of antibiotics in invasive medical procedures
(surgical prophylaxis)
- Prophylactic use of antibiotics in children suffering from viral
bronchiolitis.
FACTORS AFFECTING ANTIBIOTIC SELECTION:

3. Include:
 Efficacy
 Cost
 Toxicity
 Availability
 Culture sensitivity
 Least disturbance to normal flora (less risk of SUPERINFECTION)
 Prevents development of drug resistance.
GENERAL GUIDELINES FOR ANTIBIOTIC USE:
 Start antibiotics ONLY if there is evidence of infection
 On starting antibiotic therapy  better avoid new medications in the first
case (on proven reduced familiarity)
 Never start antibiotics in response to patient pressure
 Never prescribe antibiotics for viral infections (like common cold) for the
sake of patient satisfaction
 Use antibiotics for sufficiently long periods
 Avoid inadequate duration & dose of therapy
 Do not change an antibiotic before giving the current one a fair trial
 Consider cost-effectiveness of therapy, especially when changing antibiotics
(calculate cost for full duration of treatment)
 Acquire sufficient information about limited number of drugs of proven
efficacy & their associated ADRs
 Do not give single dose antibiotic therapy for fevers, without justifiable
localizing signs
 Conduct culture sensitivity test of samples before therapy, whenever
possible
 Avoid using too many antibiotics & drug combinations  prevents poor
diagnosis & mismanagement
 Avoid use of multiple antibiotics, except when TUBERCULOSIS is
diagnosed
 Reserve new antibiotics for SERIOUS INFECTIONS
 Prefer COMBINATION THERAPY, ONLY under the following
conditions:
- To extend covering spectrum of mixed infections

4. - To achieve synergistic bactericidal effects
- To prevent emergence of resistance organism
 While focusing on combination therapy, care must be taken so as to prevent
concurrent usage of BACTERICIDAL and BACTERIOSTATIC drugs.
Concurrent use of both can nullify the bactericidal effects of responsible
drug.
Example: Concurrent use of PENICILLIN (bactericidal) and
CHLORAMPHENICOL (bacteriostatic)  results in diminished bactericidal
of penicillin.
WORK WELL AND SMART!!
DR. VISHNU R. NAIR