Basic principles of antimicrobial therapy

Basic Principles of
Antimicrobial Therapy

Javed Iqbal, FCPS, FRCS
Professor of Surgery
Quaid-e-Azam medical College, Bahawalpur

www.surgeonjaved.com

Antibiotics are being used
very injudiciously


They are being used for
non-infective diseases


They are being used when
surgical intervention is the
answer, not the antibiotics
(alone)


They are being used for a
period less/more then
required


They are being used as a
replacement of basic
aseptic principals


Hand washing

Centers for Disease Control and Prevention
(CDC) has stated: "It is well-documented that
one of the most important measures for
preventing the spread of pathogens is effective
hand aing."


Pre-operative preparation

Bath, Shaving, Change of cloths


Theater environment

General cleanliness, Fomites, Air
handling, anaesthesia machines,
sponges, surgical techniques


So, it is thought that a
breach in any of above
can be compensated with:
An “ACHEE” ANTIBIOTICS
Which is synonymous with a “Mahngee”
antibiotic


The problem arises:

When the antibiotics is used when not
needed
or is not used appropriately when needed


This presentation must be
interpreted this context


No two human
beings are the
same


The choice of antibiotics is
never very straight forward

It needs careful assessment and
thoughtfulness


Which
antibiotic

pharma Back ground
knowledge

Hospital
cost policy


General
Principles

1 The best antibiotic is one
which is appropriate for a
particular clinical scenario.

There is no such thing as “achhi antibiotic”
Costly antibiotic is not synonymous with
“Achhi antibiotic”


The best basis to
choose an
2 antibiotic is the
microbial culture
and sensitivity
pattern.

Along with the under standing of drug
pharmacokinatics


Community
3
Acquired
vs

Hospital Acquired

Community Acquired
 Community Acquired infections are in their
“pure” form
 They are usually not resistant to standard
antimicrobials
 Their behavior is predictable
 Gram positive in throat
 Gram negative in UTI etc.


Hospital Acquired
 The infection is usually by resistant microbes
 The pattern in not predictable
 The infection is usually by mixed flora

Hospital
Hospital antibiogram
antibiogram

Infections can come
 From staff
 From Patient to patient
 From fomites
 In OT


4
If we know the bug….

The narrow spectrum antibiotic against
which the bug is sensitive should be used


5 If we don’t know the
bug….(empirical therapy)

*Drug should be broad spectrum
*Multiple drugs can be used

Broad spectrum antibiotics
 3rd generation cephalolosporins
 Carbapanum group
 Qunalones
 Ofloxacin
 Ciprofloxacin

 Levofloxacin

 Getifloxacin


Antibiogram
Selection of an
6 antibiotic for a particular
scenario is not a static
phenomenon

The antibiotics should be rotated from one
generic to another of the same group


7 If antibiotic is not giving
desired results

Please remember that there might be pus
some where in the body


8 Changing the drug vs

Changing the dose


9
Prophylactic
vs
Treatment

Prophylaxis
 Peri-operative period needs to be covered
 The drugs should be broad spectrum
 The resistant pattern should be kept in mind
 Dose may be repeated if procedure is
prolonged ( After 1-2 times of the half life of the
drug)
 Best time for prophylaxis is just at the time of
intubation
 In some cases the prophylaxis can be started
24 hours before

 Clean surgery needing skin and soft infection
First generation cephalosporin
 Surgery involving opening of a body
cavity…... 3rd generation cepalosporin
 If gut has to be opened mitronidazole has
to be added.
 Cardiac surgery Vancomycine



10

Immunological status

 Diabetes
 Steroids
 Anti cancer drugs
 AIDS
 Lympho-reticular disorders
 Anaemia


11
SEPSIS
Hospital Acquired Pneumonia
Ventilator related infections


 Sepsis is a serious medical condition

 Whole-body is in inflammatory state

 Systemic inflammatory response syndrome or

SIRS
 A lay term for sepsis is blood poisoning,

more aptly applied to septicemia


Sepsis has systemic implications:

 Decreased tissue perfusion.

 MOD leading to death
 The mortality rate from septic shock is

approximately 50%.


THE TRADITIONAL APPROACH

 Initial Use of narrow spectrum antibiotic
 Most potent drugs reserved
 Severely immunocompromised
 Nonresponders
 Resistant pathogen

 Aim is to avoid antibiotic exposure when
infection is not confirmed
 Limiting the development of resistance
 Allowing the control of cost

There is a need for Initial
Appropriate Therapy in the
Treatment of Serious
Infection

The new consences


Initial antibiotic therapy:

 Inappropriate: The microbiological
documentation of infection in the blood culture
that was not effectively treated at the time, the
causative microorganism and its antibiotic
susceptibility were known.
 Appropriate: when at least one effective drug
was included in the empirical antibiotic treatment
within 24 h of the identification of bacteremia.
This definition is in agreement with recent statements issued by the
Centers for Disease Control and Prevention.

Chest: May 2003,vol 123,1615-1624

 The traditional approach may no longer be
appropriate in the current era of
increasing antibiotic resistance

 It is important to recognize that the
excess mortality associated with
inadequate initial therapy occurred even
though the antibiotic could be switched
once the culture and susceptibility data
became available.

 The delay may have been only 2-3 days
but by that time, it was already too late.

INCREASING ANTIBIOTIC
RESISTANCE REQUIRES A
NEW TREATMENT
APPROACH


Factors involved in optimal initial antibiotic therapy.

DE-ESCALATIONn
THERAPY


De-escalation therapy
Changing from the broad spectrum
antibiotic to an agent with a narrow focus
based on culture data ;changing the focus
from multiple antibiotics to a single drug
when the suspected organism is not
detected by culture; and without fever


DE-ESCALATION
THERAPY
STAGE 1
 Administer the broadest-spectrum
antibiotic therapy to improve outcomes
(decrease mortality, prevent organ
dysfunction, and decrease hospital length
of stay).

STAGE 2
 Focus on de-escalation as a means to
minimize resistance and improve cost-
effectiveness


Carbapenems: A Good Choice for Initial
Appropriate Therapy in ICU Patients
with Serious Nosocomial Infection

The carbapenem of choice for initial appropriate
therapy should offer:
 Broad-spectrum activity
 Proven efficacy
 Low potential for resistance
 Good tolerability


Conclusions: While choosing an
antibiotic:
 Consider the patient
 Consider the site
 Consider the type of bug/s
 Consider the drug pharmacokinetics
 Consider the dosage
 Consider the route
 Consider the combination of drugs
 Consider the side effects
 Consider the cost


Thank
Thank you
very much
you


Basic principles of antimicrobial therapy

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