Jun 12, 2015
Basic Principles of Antimicrobial Therapy
Javed Iqbal, FCPS, FRCS
Professor of Surgery
Quaid-e-Azam medical College, Bahawalpur
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Antibiotics are being used very injudiciously
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They are being used for non-infective diseases
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They are being used when surgical intervention is the answer, not the antibiotics (alone)
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They are being used for a period less/more then required
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They are being used as a replacement of basic aseptic principals
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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."
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Pre-operative preparation
Bath, Shaving, Change of cloths
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Theater environment
General cleanliness, Fomites, Air handling, anaesthesia machines,
sponges, surgical techniques
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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
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The problem arises:
When the antibiotics is used when not needed
or is not used appropriately when needed
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This presentation must be interpreted this context
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No two human beings are the same
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The choice of antibiotics is never very straight forward
It needs careful assessment and thoughtfulness
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Which antibiotic
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pharma
cost
Back ground knowledge
Hospital policy
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General Principles
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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”
1
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Along with the under standing of drug pharmacokinatics
2The best basis to choose an antibiotic is the microbial culture and sensitivity pattern.
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Community Acquired
vs
Hospital Acquired
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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.
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Hospital Acquired
The infection is usually by resistant microbes The pattern in not predictable The infection is usually by mixed flora
Hospital antibiogram
Hospital antibiogram
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Infections can come
From staff From Patient to patient From fomites In OT
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If we know the bug….
The narrow spectrum antibiotic against which the bug is sensitive should be used
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If we don’t know the bug….(empirical therapy)
*Drug should be broad spectrum
*Multiple drugs can be used
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Broad spectrum antibiotics
3rd generation cephalolosporins Carbapanum group Qunalones
OfloxacinCiprofloxacinLevofloxacinGetifloxacin
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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
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If antibiotic is not giving desired results
Please remember that there might be pus some where in the body
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Changing the drug vs
Changing the dose
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Prophylactic vs Treatment
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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
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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
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Immunological status
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Diabetes Steroids Anti cancer drugs AIDS Lympho-reticular disorders Anaemia
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SEPSIS
Hospital Acquired Pneumonia
Ventilator related infections
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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
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Sepsis has systemic implications:
Decreased tissue perfusion.
MOD leading to death
The mortality rate from septic shock is
approximately 50%.
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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
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There is a need for Initial Appropriate Therapy in the Treatment of Serious Infection
The new consences
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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.
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INCREASING ANTIBIOTIC RESISTANCE REQUIRES A NEW TREATMENT APPROACH
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Factors involved in optimal initial antibiotic therapy.
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DE-ESCALATIONn THERAPY
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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
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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
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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
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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
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Thank you very muchThank you
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