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 policy

General Principles

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”

Along with the under standing of drug pharmacokinatics

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

Community Acquired

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 antibiogram

Infections can come

From staff From Patient to patient From fomites In OT

If we know the bug….

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

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

OfloxacinCiprofloxacinLevofloxacinGetifloxacin

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

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

6Antibiogram

If antibiotic is not giving desired results

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

Changing the drug vs

Changing the dose

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 openedmitronidazole has to be added.

Cardiac surgery Vancomycine

Immunological status

Diabetes Steroids Anti cancer drugs AIDS Lympho-reticular disorders Anaemia

SEPSIS

Hospital Acquired Pneumonia

Ventilator related infections

Sepsis is a serious medical condition

Whole-body is in inflammatory state

Systemic inflammatory response syndrome or

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 123,1615-1624www.surgeonjaved.com

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 you very muchThank you

Basic principles of antimicrobial therapy

best antibiotic

broad spectrum antibiotics

sepsis hospital

resistant pattern

potent drugs

multiple drugs

resistant microbes

choice of antibiotics

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