Control And Prevention Of Antimicrobial Resistant Organisms in HCF
Control and Prevention of
Antimicrobial Resistant
Organisms in HCF
Introduction
Antibiotics are used to prevent infection and to treat patients with proven or
suspected infection. The aim is to administer a safe and cost effective dose of
antibiotic that will eliminate the infecting or potentially infecting organism.
Antibiotics are widely used, contributing to 35% of all prescriptions in health care
facilities. Overuse of antibiotics results in bacterial resistance not only to the
antibiotic prescribed, but often to other antibiotics in the same classes or groups.
The abuse or misuse of antibiotics is costly because it leads to the emergence of
antibiotic resistance among microorganisms in the health care facility
environment as well as in the patients. Typically, there is a reservoir of patients
colonized with antimicrobial resistant organisms, which can be a source of cross
transmission to other susceptible patients in the facility. When infections from
Antimicrobial Resistant Organisms occur, there is increased mortality, especially
among those with underlying diseases or multiorgan failure. The health care
facility serves to amplify these strains because of the high prevalence of use of
antibiotics. The primary selective pressure for antimicrobial resistant organisms is
antibiotic use both in facilities and in communities. In under-resourced countries,
selection of resistance in communities is compounded by relatively easy access
to antibiotics and there is little regulation of this accessibility. 4 Other factors that
promote selection and transmission of these strains in all countries are failure to
complete a full course of prescribed antibiotics, and lack of resources and
personnel for facility infection control programs. In addition, even countries that
spend considerable resources on health care do not necessarily have a lower
frequency of antimicrobial resistant organisms. 62
Normal microbial flora is protective. The administration of antibiotics kills off
susceptible strains of normal bacteria and these are replaced with resistant
strains, which are often resistant to many different classes of antibiotics. This
replacement occurs most often in the gastrointestinal tract, which carries the bulk
of bacteria, and results in stool carriage of multiply antibiotic resistant bacteria.
These antimicrobial resistant organisms bacteria can easily spread from patient
to patient in the hospital environment via hands of staff, bedpans, and nonclinical and poorly sterilized equipment.
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Control And Prevention Of Antimicrobial Resistant Organisms in HCF
Examples of antimicrobial resistant organisms
The misuse of antibiotics has led to the emergence of multiple antibiotic resistant
bacteria in both gram positive and gram-negative bacteria 63. .
Gram Positive Cocci
Enterococci and coagulase negative staphylococci have emerged as significant
pathogens in recent years, although previously considered as commensals or
normal flora.

Staphylococcus aureus has now acquired resistance to cloxacillin and
vancomycin. 64

Methicillin (Flucloxacillin) resistant Staphylococcus aureus (MRSA) is
common in most hospitals worldwide and is particularly concentrated in high
risk units such as Intensive care units and Neonatal Intensive care units.

Blood stream infections associated with IV sites, ventilator associated
pneumonia, and infections at surgical sites and of prosthetic implants are all
common infections associated with gram-positive cocci.
Gram Negative Bacilli
Gram-negative bacteria have become more resistant to routine antibiotics.

Extended spectrum B-lactamases are now common in Klebsiella
pneumoniae, particularly in high risk units such as Intensive care units
and Neonatal Intensive care units.

Acinetobacter spp is wide spread in most Intensive care units
worldwide and is highly resistant to most antibiotics.

Pseudomonas aeruginosa can be isolated from wounds and from
respiratory and urinary tracts of patients in most hospitals. It is also
present in the hospital environment in open containers of disinfectant,
in wet or moist areas, and on equipment.

Once introduced into a high risk unit, gram negative bacilli are very
difficult to eliminate.

Antimicrobial resistant organisms gram negative bacilli can cause any
type of infection but are particularly common causes of blood stream
infections, ventilator associated pneumonia, urinary tract infections, IV
fluid infusion site infections, and surgery and burn site infections.
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Control And Prevention Of Antimicrobial Resistant Organisms in HCF
Acquisition and Transmission of
Antimicrobial Resistant Organisms
Note:
A distinction should be made between acquisition and transmission of multiple
drug resistant organism pathogens. The misuse of antibiotics leads to acquisition
of antibiotic resistance organisms, while poor infection control procedures lead to
the transmission of antimicrobial resistant organisms.
Acquisition
Antimicrobial Resistant Organisms are created by selective pressure from
antibiotics. Antibiotic pressure is more noticeable when certain classes of
antibiotics are used. The most commonly prescribed antibiotics are betalactamases such as penicillins and cephalosporins. The latter are now
recognized as having a significant role in the emergence of antibiotic resistance
among bacteria, which were previously considered sensitive or commensal flora.
Large amounts of antibiotics are used in the health care setting, especially in the
ICU, and can lead to the emergence of resistant strains.
Community factors can also cause antibiotic pressure. Wide scale usage of
antibiotics for minor ailments can select for resistant pathogens which are then
circulated in the community (wide scale resistance of S. pneumonia has been
well described in numerous countries).
Transmission
Having acquired antibiotic resistance, the microbe has to have certain attributes
in order that it may spread:

Microbial fitness: ability to produce a clone, which can be transmitted from
host to host.

Virulence: ability to attach and invade tissues.
Acquisition of resistance is not a normal activity for the microbe. It takes
increased expenditure of energy to develop resistance. Therefore the efficiency
of transmission of these antimicrobial resistant organisms may be less,
compared to susceptible strains.
Strategies for reducing transmission of antimicrobial resistant
organsims:

An infection control policy that is simple and effective, such as one that
emphasizes good hygiene. Of note, this strategy not only addresses
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Control And Prevention Of Antimicrobial Resistant Organisms in HCF
antimicrobial resistant organisms but susceptible strains, which can also
cause considerable morbidity and mortality.

Knowledge of the infection control policy by all personnel.

Repeated emphasis on hand hygiene.

Appropriate use of personal protective equipment (PPE).

Use of surveillance data to target specific areas at high risk for
antimicrobial resistant organisms.

Identify bacterial isolates per patient rather than identification of isolates
per site.

A well controlled testing system in place.

Development of lab capacity to correctly identify antibiotic sensitivity
patterns.

Use of spatial separation between patients known to be infected or
colonized with MRSA or VRE and patients who are not known to be
infected or colonized.

If resources for physical barriers are limited, establishment of a glove
policy and hand hygiene policy are priorities.

The goal of microbiologic screening of patients for antimicrobial resistant
organisms must be identified before it is undertaken. Variables to consider
are whether this is cost effective and whether appropriate laboratory
support is available. Screening may be considered as part of an
epidemiologic investigation of possible outbreak or cluster.

Do not screen personnel unless they are epidemiologically linked to
ongoing transmission. There is no evidence that antimicrobial resistant
organisms are less susceptible to soap/detergent products or antiseptic
agents when compared to antibiotic susceptible organisms.

If only soap and water are available for hand hygiene then reinforce its
use. Evidence does suggest however that removal of antimicrobial
resistant organisms from hands is improved if hand antisepsis is utilized.
This is especially applicable for high risk areas/populations (Intensive
Care Units, Dialysis, etc.).

Extraordinary environmental cleaning or disinfection is not needed for
preventing transmission of antimicrobial resistant organisms. There is little
evidence that use of disinfectants or antiseptics in health care facilities is
selecting for antimicrobial resistant organisms.
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Control And Prevention Of Antimicrobial Resistant Organisms in HCF
Table 17: Control of antibiotic resistance
Procedure
Effect on acquisition
+
(antibiotic dependent)
Lack of IC procedures
none
Absence of surveillance none
of antibiotic resistance
Absence of treatment +++
protocols or guidelines
Misuse of antibiotics
Effect on transmission
++
(bacteria dependent)
++
++
++
Antibiotic Usage
Antibiotic Prophylaxis
Prophylactic antibiotics are mainly used for surgery (and other invasive
procedures). Maximum blood levels of antibiotic at the time of the procedure help
ensure that circulating bacteria arising during the procedure can be reduced to a
level that can be destroyed by the patient’s body’s natural defenses.
There is no benefit in starting antibiotics too early or in continuing for longer than
24 hours after the procedure. Instead this can result in emergence of resistance.

A single dose or a maximum of three doses should be administered
starting with the induction of anesthesia.

Prophylaxis should not continue longer than 24 hours.

After 24 hours antibiotics are considered treatment and should be
documented as such, for example, in cases of perforation and peritonitis.
Antibiotic Therapy
Antibiotics are used to treat patients with known or suspected infection:
Empiric therapy is based on the ‘best-guess’ antibiotic for the suspected
organism and its predicted antibiotic sensitivity patterns. Knowledge of local
antibiotic sensitivity patterns is useful so that prescribing is not based on
publications from other countries. The decision should be based on:

The site of infection.

The probable pathogen.

The known bacterial spectrum.

Safety and pharmacokinetics of the chosen antibiotic.
If clinical response is noted in 72 hours, then the therapy should be continued
through completion. If there is no improvement or if the clinical picture changes,
then alternative antibiotics must be considered. The range of antibiotics is broad
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Control And Prevention Of Antimicrobial Resistant Organisms in HCF
and a combination of two or more may be used initially. This may be reduced to
one when the bacteriology results become available.
Targeted therapy is instituted when microbiological results are known or when
the results are pending but the clinical picture requires immediate treatment. An
example would be treating meningococcal meningitis on the basis of a gram stain
from the cerebrospinal fluid.
Formulating an Antibiotic Policy
It is difficult to formulate a general antibiotic policy because bacterial populations
and antibiotic resistance patterns differ between hospitals, clinical choices vary,
availability of antibiotics differs from country to country, and because route and
cost of antibiotic administration varies. 9 There have been reports of successful
lowering of frequency of antimicrobial resistant organisms by controlling or
removing selective pressure from overuse of antibiotics.18, 66, 67 Each health care
facility should have an antimicrobial management program that monitors use of
antibiotics.
When formulating a policy consider doing the following:

List the available
pharmacokinetics.

List the indications for which antibiotics are required. Are they needed for
prophylaxis or therapy?

Determine indications for use of each antibiotic after consultation with the
clinicians.

When the policy has been agreed ensure that Microbiology can test for
sensitivities of selected pathogens to these antibiotics.

Enter the policy in the hospital formulary and display the policy on the
walls of the wards.

Review the policy periodically. Policies should change if there are changes
in the antibiotic resistance patterns, a change in the functions of a unit, a
change in staff, a price increase in a certain antibiotic, , or if there are new
antibiotics on the market.
antibiotics
of
similar
spectrum,
safety
and
Note:
Antibiotic Formularies or policies should be determined by the Drugs and
Therapeutics Committee and should be established after wide consultation with
the clinical and hospital staff. It requires ownership by the staff and needs
constant support from antibiotic surveillance (Microbiology). All policies should be
reviewed after 18 months.
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Control And Prevention Of Antimicrobial Resistant Organisms in HCF
All Antibiotic policies need to consider a few basic principles:

The goal is to assure treatment of confirmed infection and not to cause
unnecessary colonization of resistant strains.

Use different classes of antibiotics for prophylaxis and therapy.

Use a high dosage for a short duration therapy.

The antibiotics chosen for the policy should be rotated after a set period of
time in order to reduce selective pressure.

The policy should contain information on the class of antibiotic and the
possible impact that this class could have on emergence of resistance.
Table 18: Antibiotics against nosocomial infections
Penicillins
ANTIBIOTIC
Penicillins
Aminopen. +
inhibitor (BLI)
beta
lactamase
Acylamidopenicillins
Acylamidopenicillins+ BLI
Isoxazolylpenicillins
EXAMPLE
Benzyl penicillin
ACTIVE AGAINST
Meningo-, strepto-, pneumococci
Amoxycillin + clavulanic acid
Staphylococci
Azlocillin
Piperacillin
Piperacillin + tazobactam
Cloxacillin
Flucloxacillin
Enterococci
P. aeruginosa
P. aeruginosa
EXAMPLE
Cefazolin
Cefaclor
Cefuroxime
Cefotaxime
Ceftriaxone
ACTIVE AGAINST
S. aureus
Cephalosporins
ANTIBIOTIC GROUP
1st Generation
2nd Generation
3rd Generation
4th Generation
Staphylococci
Staph., strept,enterobacteria
Gram negatives
Strept., pneumococci
Gram negatives,
P. aeruginosa
Gram negatives, anaerobes
Ceftazidime
Cefoxitin
Carbapenems
ANTIBIOTIC GROUP
EXAMPLE
Imipenem
Meropenem
ACTIVE AGAINST
Gram positive
Gram negative+ anaerobes
ANTIBIOTIC GROUP
EXAMPLE
2nd Group
Ofloxacin
Ciprofloxacin
3rd Group
Levofloxacin
ACTIVE AGAINST
Enterobacteria (staphylococci,
enterococci.)
P. aeruginosa
Gram positive + gram negative
Carbapenems
Quinolones
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Control And Prevention Of Antimicrobial Resistant Organisms in HCF
Aminoglycosides
ANTIBIOTIC GROUP
EXAMPLE
Gentamicin
Netilmicin
Tobramicin
Amikacin
ACTIVE AGAINST
Enterobacteria
Enterobacteria
Enterobacteria + P. aeruginosa
Enterobacteria + P. aeruginosa
ANTIBIOTIC GROUP
EXAMPLE
Makrolides
Erythromycin
Lincosamides
Clindamycin
ACTIVE AGAINST
Gram positive cocci
L. pneumophila
C. jejuni
Gram positive cocci
Anaerobes (Bacteroides,
Clostridium)
Glycopeptides
Vancomycin
Teicoplanin
Streptogramines
Quinupristine / dalfopristine
Rifamycins
Rifampicin
Aminoglycosides
Other groups:
Gram positive,( MRSA, enterococci)
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GRSA , VRE
Gram positive cocci
Mycobacteria
(not used as monotherapy)