By Dr Md Main Uddin (MBBS, FCPS) Assistant Professor (Medicine) Cox’s Bazar Medical College Bangladesh

1. RATIONAL USE OF
ANTIBIOTICS
Dr Md Main
Uddin
Assistant Professor
(Medicine)
Cox’s Bazar Medical
College

2. Contents
 Introduction
 Empiric versus targeted therapy
 Therapy with combined Antimicrobial
agents
 Choice of a suitable drug
 Misuses of Antibiotics
 Conclusion

3. Introduction
 The global use of antibiotics/antibacterial
drugs have improved the health of humans
and animals since the antibiotic golden age
and the economy of many countries
worldwide.
 These agents are used in the treatment of both
human and animal bacterial diseases. They
are used by livestock farmers as feed additives
to enhance growth of livestock animals.
 They are used in food industries as
preservatives and in commercial ethanol
production to prevent bacterial contaminants of

4. DEFINITION
Antibiotics are chemical substances obtained
from microbes/microorganisms (bacteria, fungi,
actinomycetes) that able to inhibit the growth or
kill the other microorganisms.
Antimicrobial all antiinfections
semisynthetic
synthetic
nature  antibiotics

5. Ehrlich’s Magic Bullets
PaulEhrlich’s
discovered
arsphenamines
in1910,
sulfadrugsin1935

6. Fleming and Penicillin
Discovered in 1928

7. ?
Bad bugs need new drugs
Linezolid

8. Abstract
 We have done a retrospective study on
morbidity and mortality of Communicable
diseases in District Sadar Hospital Cox’s
Bazar from July’2010 to June ’2011. All
patients admitted to Medicine ward were
included. Total numbers of patients are 10208,
male 4959, female 5249. Total number of
infectious diseases are 1641(about 16%),
male 883, female 758.

9.  UTI is the commonest one, total 408, male 110,
and female 298. Enteric fever is the second
commonest cause of admission, total 246, male
152, and female 94. Tuberculosis is still a major
threat to community, total 98 pulmonary and 23
extra pulmonary cases are found. In 433 cases
diagnosis is mentioned as AFI (Acute Febrile
Illness), no etiological agent mentioned, viral
infection is a logical possibility. Other top four
causes of admission to medicine ward are Acute
Viral Hepatitis (AVH) (124), Upper Respiratory
Tract Infection (URTI) (95), Malaria (69) and

10. RATIONAL PRESCRIBING
Like any other process in health care, writing a
prescription should be based on a series of
rational steps.
(1) Make a specific diagnosis: Prescriptions
based merely on a desire to satisfy the patient's
psychological need for some type of therapy are
often unsatisfactory and may result in adverse
effects.
(2) Consider the pathophysiologic
implications of the diagnosis: If the disorder is
well understood, the prescriber is in a much better
position to offer effective therapy.

11. (3) Select a specific therapeutic objective
(4) Select a drug of choice
(5) Determine the appropriate dosing
regimen
(6) Devise a plan for monitoring the drug's
action and determine an end point
for therapy
(7) Plan a program of patient education

12. Empiric versus targeted therapy

13. Therapy with Combined
Antimicrobial Agents
 Indications for the Clinical Use of
Combinations of Antimicrobial Agents
 Use of a combination of antimicrobial agents
may be justified (1) for empirical therapy of an
infection in which the cause is unknown, (2) for
treatment of polymicrobial infections, (3) to
enhance antimicrobial activity (i.e., synergism)
for a specific infection, or (4) to prevent
emergence of resistance.

14. Empirical Therapy of Severe
Infections in Which a Cause Is
Unknown
 In the treatment of community-acquired
pneumonia, a macrolide is used for atypical
organisms such as Mycoplasma, and
cefuroxime is used for pneumococci and gram-
negative pathogens.

15. Treatment of Polymicrobial
Infections
 Treatment of intra-abdominal, hepatic, and
brain abscesses and some genital tract
infections may require the use of a drug
combination to eradicate these typically mixed
aerobic-anaerobic infections.

16. Enhancement of Antibacterial
Activity in the Treatment of Specific
Infections
 Perhaps the best-documented example of the
utility of a synergistic combination of
antimicrobial agents is in the treatment of
enterococcal endocarditis. In vitro, penicillin
alone is bacteriostatic against enterococci,
whereas a combination of penicillin and
streptomycin or gentamicin is bactericidal.
 B-Lactam antibiotic-aminoglycoside
combinations have been recommended in the
therapy of infections with Pseudomonas
aeruginosa.

17.  Combination therapy has been advocated for the
treatment of infections caused by other gram-negative
rods. However, the benefits of using a drug
combination over a single, effective agent remain
largely unproven.
 The combination of a sulfonamide and an inhibitor of
dihydrofolate reductase, such as trimethoprim, is
synergistic owing to the blocking of sequential steps in
microbial folate synthesis. A fixed combination of
sulfamethoxazole and trimethoprim, which is active
against organisms that may be resistant to
sulfonamides alone, is effective for the treatment of
urinary tract infections, Pneumocystis pneumonia,
typhoid fever, shigellosis, and certain infections owing
to ampicillin-resistant Haemophilus influenzae.

18. Prevention of the Emergence of
Resistant Microorganisms
 The theoretical basis for combination therapy
of tuberculosis is to prevent the emergence of
resistant mutants that might result from
monotherapy.
 Combination therapy of Helicobacter pylori
infection.

19. Disadvantages of Combinations
of Antimicrobial Agents
 Disadvantages of antimicrobial
combinations include increased risk
of toxicity from two or more agents,
selection of multiple-drug-resistant
microorganisms, eradication of
normal host flora with subsequent
superinfection, and increased cost to
the patient.

20. Choice of a suitable drug
Before selecting an antibacterial the clinician must first
consider two factors—the patient and the known or likely
causative organism.
Factors related to the patient which must be considered
include history of allergy, renal and hepatic function,
susceptibility to infection (i.e. whether
immunocompromised), ability to tolerate drugs by
mouth, severity of illness, ethnic origin, age, whether
taking other medication and, if female, whether
pregnant, breast-feeding or taking an oral contraceptive.

21.  The dose of an antibacterial varies according
to anumber of factors including age, weight,
hepatic function, renal function, and severity of
infection.
 The prescribing of the so-called ‘standard’
dose in serious infections may result in failure
of treatment or even death of the patient;
therefore it is important to prescribe a dose
appropriate to the condition.

22.  An inadequate dose may also increase the
likelihood of antibacterial resistance.
 On the other hand, for an antibacterial with a
narrow margin between the toxic and
therapeutic dose (e.g. an aminoglycoside), it is
also important to avoid an excessive dose and
the concentration of the drug in the plasma
may need to be monitored.

23.  The route of administration of an antibacterial
often depends on the severity of the infection.
Life-threatening infections require intravenous
therapy.
 Antibacterials that are well absorbed may be
given by mouth even for some serious
infections.
 Parenteral administration is also appropriate
when the oral route cannot be used (e.g.
because of vomiting) or if absorption is
inadequate.
 Whenever possible, painful intramuscular

24.  Duration of therapy
depends on the
nature of the
infection and the
response to
treatment.

25. Misuses of Antibiotics
 Treatment of Nonresponsive Infections. A
common misuse of these agents is in infections
that have been proved by experimental and clinical
observation to be nonresponsive to treatment with
antimicrobial agents.
 Most of the diseases caused by viruses are self-
limited and do not respond to any of the currently
available anti-infective compounds.
 Thus, antimicrobial therapy of measles, mumps,
and at least 90% of infections of the upper
respiratory tract and many GI infections is
ineffective and, therefore, useless.

26. Therapy of Fever of Unknown
Origin
 Fever persisting for 2 or more weeks, commonly
referred to as fever of unknown origin, has a
variety of causes, of which only about one-quarter
are infections.
 Some of these infections (e.g., tuberculosis or
disseminated fungal infections) may require
treatment with antimicrobial agents that are not
used commonly for bacterial infections.
 Others, such as occult abscesses, may require
surgical drainage or prolonged courses of
pathogen-specific therapy, as in the case of
bacterial endocarditis.

27.  Inappropriately administered antimicrobial therapy
may mask an underlying infection, delay the
diagnosis, and by rendering cultures negative,
prevent identification of the infectious pathogen.
 Noninfectious causes, including regional enteritis,
lymphoma, renal cell carcinoma, hepatitis,
collagen-vascular disorders, and drug fever, do
not respond to antimicrobial agents at all.
 Rather than embarking on a course of empirical
antimicrobial therapy for fever of unknown origin,
the physician should search for its cause.

28. Improper Dosage
 Dosing errors, which can be the wrong frequency
of administration or the use of either an excessive
or a subtherapeutic dose, are common.
 Although antimicrobial drugs are among the safest
and least toxic of drugs used in medical practice,
excessive amounts can result in significant
toxicities, including seizures (e.g., penicillin),
vestibular damage (e.g., aminoglycosides), and
renal failure (e.g., aminoglycosides), especially in
patients with impaired drug excretion or
metabolism.
 The use of too low a dose may result in treatment
failure and is most likely to select for microbial
resistance.

29. Inappropriate Reliance on
Chemotherapy Alone
 Infections complicated by abscess formation, the
presence of necrotic tissue, or the presence of a
foreign body often cannot be cured by
antimicrobial therapy alone.
 As a general rule, when an appreciable quantity of
pus, necrotic tissue, or a foreign body is present,
the most effective treatment is an antimicrobial
agent given in adequate dose plus a properly
performed surgical procedure.

30. Lack of Adequate Bacteriological
Information
 Frequent use of drug combinations or drugs
with the broadest spectra is a cover for
diagnostic imprecision.
 The agents are selected more likely by habit
than for specific indications, and the dosages
employed are routine rather than
individualized on the basis of the clinical
situation, microbiological information, and the
pharmacological considerations.

31. Misuses of Antibiotics with positive
Widal test

33. Percent change in antibiotic consumption,
out-patient care in 25 European countries 1997-2003
Data from ESAC
-20
-15
-10
-5
0
5
10
15
20
25
Poland
C
roatia
G
reece
Ireland
Portugal
D
enm
ark
Luxem
bourg
H
ungary
Italy
Slovakia
Israel
N
orw
ay
Sw
eden
Austria
Slovenia
Estonia
Finland
Spain
The
N
etherlands
G
erm
any
Belgium
Iceland
C
zech
R
epublic
U
K
France
Percentchange
For Iceland, total data (including hospitals) are used
Co-ordination programs and national campaigns
Slide courtesy of Otto Cars, STRAMA, Sweden

34.  An example of a rational approach to the
selection of an antibacterial is treatment of a
urinary-tract infection in a patient complaining
of nausea and symptoms of a urinary-tract
infection in early pregnancy.

35.  The organism is reported as being resistant to
ampicillin but sensitive to nitrofurantoin (can
cause nausea), gentamicin (can be given only
by injection and best avoided in pregnancy),
tetracycline (causes dental discoloration) and
trimethoprim (folate antagonist therefore
theoretical teratogenic risk), and cefalexin.
 The safest antibiotics in pregnancy are the
penicillins and cephalosporins; therefore,
cefalexin would be indicated for this patient.

37. Conclusion
 Massive use of the antibiotics/antibacterial drugs
in irrational manner has affected the ecosystem,
destruction of useful bacteria in the environment
including the normal flora as well as increasing
the selection of the pathogenic antibiotic resistant
bacterial organisms that have led to their spread
globally.
 These problems are likely to increase in future
unless there is an urgent instituting of control
measures involving all stakeholders on the
rational use of antibiotics/antibacterial drugs
globally.

38. Treat bacteria not fever

39. “The desire to ingest medicines is
one of the principal features which
distinguish man from the animals”
William Osler 1920

40. Thank You