CLINICAL UTILITY OF ANTIBIOGRAMS

Dr.T.V.Rao MD If we look at our responsibilities as medical Microbiologists, the little work we do in diagnostic laboratories remain with bacterial cultures, and Antibiotic Sensitivity testing pattern of Aerobic isolates from common specimens sent to our laboratories, with emerging automation the clinical microbiologists have greater role to interpret the matters on antibiotic resistance and sensitivity pattern and certainly helps to forecast the events on emerging Antibiotic resistance clinical setting where we work with many terminally ill and patients lodged in super specialty care , As Antibiograms are important tools for health care professionals involved in prescribing empiric antibiotics for suspected bacterial infections. Going to the basics, what is Antibiogram? An overall profile of antimicrobial susceptibility of a microbial species to a battery of antimicrobial agents. A tool for healthcare providers to use local antibiotic susceptibility data as recommended by the CDC to provide guidance in their prescribing practice. Only the first isolate from the patient is to be included in the analysis. However it has its own controversies bigger area of understanding is in need, The analysis should be done on the basis of patient location and specimen type. The percentage susceptibility of the most frequently isolated bacteria should be presented in the antibiogram, preferably in a tabular form. The antibiogram must be printed or put up in the intranet for easy access to all clinicians Collaborating with hospitals Hospital antibiogram are commonly used to help guide empiric antimicrobial treatment and are an important component of detecting and monitoring trends in antimicrobial resistance. To serve these purposes, antibiogram must be constructed using standardized methods that allow inter- and intra-hospital comparisons These tools utilize micro biologic data from patient specimens from a Medical establishment or nursing facility to estimate the ward- or facility-wide prevalence of antibiotic susceptibilities for common Bacterial pathogens. The hospital antibiogram is a periodic summary of antimicrobial susceptibilities of local bacterial isolates submitted to the hospital's clinical microbiology laboratory. Antibiogram are often used by clinicians to assess local susceptibility rates, as an aid in selecting empiric antibiotic therapy, and in monitoring resistance trends over time within an institution. Anti-microbial susceptibility data are often considered when deciding if a particular antimicrobial will be included in the anti-infective section of a drug formulary Antibiogram are also used to compare susceptibility rates across institutions and track resistance trend They are also an important component of monitoring trends in antimicrobial resistance within different areas of a facility. Hospitals use antibiogram as part of their infection control measures to classify types of bacteria found in cultures, to identify patterns of antibiotic susceptibility in those bacteria, and to track changes in antibiotic susceptibility over time. Hospitals use these cumulative antimicrobial susceptibility test data reports to determine the most appropriate agents for initial empirical antimicrobial therapy and to target efforts to reduce inappropriate antibiotic use. Selection of empiric therapy in a particular patient should not be based solely on an antibiogram. Patient’s particular infection history, including past antimicrobial use, must also be considered. Antibiogram provide guidance for empiric antibiotic use in patients, but other factors including patient characteristics and prevalence of other risk factors should be incorporated when making therapeutic decisions. They do not even reveal if the organism was causing infection or was simply a colonizing strain. Antibiogram reveal qualitative measures of susceptibility (i.e., whether a pathogen is resistant or susceptible) but do not provide quantitative data, such as minimum inhibitory concentrations (MICs). Hospital antibiogram can be a useful means for guiding empiric therapy and tracking the emergence of bacterial resistance among nosocomial isolates. However, variability in the manner in which antibiogram are constructed and reported introduces confounding that impedes intra- and inter hospital comparisons. Although the CLSI published the M39-A guidance document on standardizing anti-biogram construction and reporting, data suggest that few medical centres have adopted all elements of this document. Until there is greater and more predictable compliance with the M39-A document, it would be extremely valuable to have the construction methodologies notated on the antibiogram so that the approach is transparent. Notations should specify the methodology applied to duplicate isolates and the time frame designated for excluding duplicate isolates. This way, when antibiogram data are used to compare antimicrobial resistance rates among hospitals, different methodologies used to generate susceptibility data can be accounted for. The recommendations in M39-A3 are intended to be used by individuals involved in the following: analyzing and presenting antimicrobial susceptibility test data utilizing cumulative antimicrobial susceptibility test data to make clinical decisions; and designing information systems for the storage and analysis of antimicrobial susceptibility test data One of the recommendations for prevention and control of multi drug-resistant organisms is for institutions to have a multidisciplinary process in place to review local antibiogram and antimicrobial drug use to enhance appropriate antimicrobial use, The WHONET software can be freely downloaded and used for analysis. Consensus guidelines have been developed by the Clinical and Laboratory Standards Institute (CLSI) to standardise methods used in constructing antibiogram. However all the matters related to what to prescribe, and best the best option remain with clinician as the test results can be used to guide antibiotic choice. The results of antimicrobial susceptibility testing should be combined with clinical information and experience when selecting the most appropriate antibiotic for patients. Despite the statistical limitations, some conclusions remain valid: AST is nuanced and complex, and automated instrumentation does not eliminate the need for well-trained, experienced clinical microbiologists to oversee testing and review data. I WISH MANY CLINICAL MICROBIOLOGISTS TO ASCERTAIN ROLE IN THE CLINICAL CARE OF

THE PATIENTS, AND INTERPRETATION ON MATTERS RELATED TO ANTIBIOGRAMS Ref 1 CLSI Publishes Guideline for Analysis and Presentation of Cumulative Antimicrobial Susceptibility Test Data2 Systematic Review of Antibiogram: A National Laboratory System Approach for Improving Antimicrobial Susceptibility Testing Practices in Michigan Martha S. Boehme, MLS (ASCP)CMaPatricia A. Somsel, DrPHbFrances Pouch Downes, DrPHa - Public Health LaboratoriesDr.T.V.Rao MD Professor of Microbiology Freelance writer