ANTIBIOTIC POLICY ROLE OF DIAGNOSTIC MICROBIOLOGY LABORATORY

1. ANTIBIOTIC POLICY
ROLE OF DIAGNOSTIC MICROBIOLOGY LABORATORY
Dr.T.V.Rao MD
Many Hospitals in India have to develop the practicable Infection control and
Antibiotic policy. Yet no practically defined solutions to forecast the emerging resistance in bacterial
isolates If you scrutinise the patient case sheets, many patients are subjected to multiple antibiotic
use and in turn the path to recovery is complex and unpredictable and many times patients will be
spending life time resources just on antibiotics. However the young Microbiologists should make the
matters simple in understanding the basic facts on Antibiotic resistance
Use Standards on Reporting Results should use standards for reporting quantitative
resistance data (e.g. minimal inhibitory concentrations or zone diameters) that will detect decreased
susceptibility. This is necessary because numerical antimicrobial test results reported
qualitatively (e.g., as susceptible, intermediate, or resistant) may hide an emerging resistance
character in microorganisms with a small decrease in susceptibility that may still be classified as
susceptible. If you look into some of the CLSI guidelines the minimal changes are taking every year
may be even <2 mm zone sizes, updating the information becomes difficult, in spite of our best
efforts we will be missing resistance to new generation antibiotics, If we Microbiologists
communicate with professionals in the reputed organization can help us to get updated information,
or else patients lose the advantage of effective antibiotic therapy.
Generate reliable numerator It is crucial to avoid including duplicate results since a patient
may have either consecutive cultures obtained from the same body site or cultures from
different body sites yielding the same organism (e.g., urine and blood culture). Therefore, only the
first positive culture from the patient for each disease episode should be reported for surveillance
purposes. If we are including many repeated specimens in surveillance it causes confusion in making
the Data from the laboratory .This will be the reliable numerator for the antimicrobial resistance
surveillance.
Express resistance as incidence rate – what incidence means is true incidence is ‘the
number of instances of illness commencing, or of persons becoming ill’ (or dying or being hurt in
injuries, or drug resistance patterns whatever choose to forecast ) ‘during a given period in a
specified population’ (Last 2001). When most people use the term they mean the incidence rate,
which differs slightly in that it is the rate at which events occur in a population (Last year 2012). In
other words, incidence usually means something that is measured within a set number of people
and in a time period present year say 2013). It is important that we should not confuse with
prevalence rates, Prevalence (or to be more correct, prevalence proportion and sometimes point
prevalence) gives a figure for a factor at a single point in time (Jekel et al2001) The important words
are ‘at that point in time’ because prevalence can tell us only what is happening at a certain point.as
we talking about the data recordings of our laboratory as they pertain to the day to day working
with specimens received in the laboratory. It simply means prevalence of Antibacterial susceptibility
or resistance. It is important to express antimicrobial resistance rates as incidence rates within

2. a defined human population instead of using the number of isolates tested as denominators. This
is imperative because the submission of microbiology specimens to the laboratory is inconsistent
and varies broadly. In hospital settings, it is recommended to use the number of admissions and the
number of days of hospitalization, which are particularly useful for inter- or intra-health-care facility
comparison. It should be recognized that this process captures data only from patients
admitted to health facility and excludes those who attend as outdoor patients. Incidence can tell us
how many new cases of drug resistance been prevailing in a community, or it might tell us how
patterns of a condition within a population change over time. Unless we analyse the trends of
Antibacterial resistance in a given population or society we will not be able to forecast the existing
incidence of antibiotic resistance to any particular antibiotic we use or/ and changing trends in
antibiotic resistance in a given population.
The other considerations for an effective antimicrobial resistance surveillance include: Clinical
microbiologists should be trained in health-care epidemiology. The choice of micro-organisms and
antimicrobials to survey should be based on their relative public health importance, using criteria
such as expected numbers of cases, severity of the infectious disease as measured by its
mortality rate and case-fatality ratio, medical costs of such infections, and preventability
missing from surveillance reports, however that all Microbiologists should Insist to fill all the patient
data on the Clinical request forms.
A well-structured computer system with WHO (WHONET) open source software can be used for data
entry and analysis (http://www.who.int/ drug resistance/whonetsoftware/en/). The analysis
should be done at regular intervals and the results/observations should be shared within the
institution, with community and collaborative study groups. The WHONET if implemented in
Diagnostic laboratories, many matters on drug resistance are at our finger tips with a click of a
mouse which can be analysed with wisdom to asses and document changing trends in the Drug
resistance patterns, which can be forecasted at regular intervals.
Ref - Facts of information are generated from Step-by-step approach for development and
implementation of hospital antibiotic policy and standard treatment guidelines prepared by WHO
Dr.T.V.Rao MD Professor of Microbiology Freelance writer