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Antibiogram CLSI Recommendations By: Dr Mostafa Mahmoud PhD, Consultant Microbiologist, Riyadh, MOH Assist. Professor of Medical Microbiology & Immunology, Faculty of Medicine, ASU, Cairo, Egypt.

Antibiogram CLSI Recommendations

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Antibiogram

AntibiogramCLSI Recommendations By: Dr Mostafa Mahmoud PhD,Consultant Microbiologist, Riyadh, MOHAssist. Professor of Medical Microbiology & Immunology, Faculty of Medicine, ASU, Cairo, Egypt.

What is an Antibiogram (ABG)? An antibiogram is an overall profile of antimicrobial susceptibility testing (AST) results of a specific microorganism to a battery of antimicrobial drugs. This profile is generated by the laboratory using aggregate data from a hospital or healthcare system; data are summarized periodically and presented showing percentages (%) of organisms tested that are susceptible to a particular antimicrobial drug. Only results for antimicrobial drugs that are routinely tested and clinically useful should be presented to clinicians.

How to measure the antimicrobial susceptibility in the micro lab?1- Disc Diffusion (DD) method and E-test (Manual labs). 2- The broth dilution (MIC) method either macro or microdilution (Automated labs).

1- Disc Diffusion method (Manual labs)

Disc DiffusionRing Disc DiffusionE- Test.

2- Broth Microdilution (Microscan)

2- Broth Microdilution (Phoenix)

2- Broth Microdilution (Vitek 2)

Recommendations for Antibiograms:Analyze/present cumulative antibiogram report at least annually;Include only final, verified test results;Include only species with testing data for 30 isolates.Include only diagnostic (not surveillance) isolatesEliminate duplicates by including only the first isolate of a species/patient/analysis period, irrespective of body site or antimicrobial profileInclude only antimicrobial agents routinely tested; do not report supplemental agents selectively tested on resistant isolates only. Report %S (Susceptible) and do not include %I (intermediate) in the statistic.

Antibiogram Uses: 1- Antibiograms help guide the clinician and pharmacist in selecting the best empirical antimicrobial treatment in the event of pending microbiology culture and susceptibility results.

2- They are also useful tools for detecting and monitoring trends in antimicrobial resistance.

Scope of applications of ABG:1- Staff working in analysis and presentation of AST data (e.g. clinical microbiologists, pharmacists, physicians).2- Staff utilizing cumulative AST data to make clinical decisions (e.g. clinical microbiologists, infectious disease specialists and other clinicians, infection control practitioners, pharmacists, epidemiologists, other health care personnel, and public health officials).3- For designing information systems for the storage and analysis of AST data (e.g. laboratory information system [LIS] vendors, manufacturers of diagnostic products that include epidemiology software packages).

Data Required to perform ABG:1.Patient: - Required: ID, - Desirable: Age, Sex, Location (Ward), Admission date; 2. Specimen information: - Required: number, type & date of collection.- Desirable: Body site e.g. right or left

3.Organism information: - Required: identification up to the genus or species level (genus can be satisfactory).- Desirable: Isolate number, change in name of isolate (if happen), Infection control data e.g. colonization or infection, community-acquired, or healthcare associated CA or HAI 4.AST information: - Required: final MIC or zone diameter (ZD) used, method used, special tests for detection of B-lactamase, mecA gene, PBP2a by agar screening , PCR or latex testing respectively.- Desirable: detailed MIC or ZD

Frequency of PerformanceAt least once yearly.More frequent with high number of isolates, new antimicrobial introduced, or presence of important medical changes.

Facility: ABG is performed based upon local institution-specific susceptibility data.

Data presentation:In a tabular form.No universal formatsSeparate tables for Gram-positive, and Gram-negative, also for anaerobes and yeasts if applicable.Arrange the organisms within the table alphabetically, by organism group of by the prevalence.

Some labs may present data by body site e.g. urine gram-negative or gram-positive.Antibiogram for critical care units (more resistant) e.g. ICUs better to be separated to compare %S with the total hospital.Comments upon the table must be included to explain it.Recommended species to be included (even if 30 isolates to be statistically significant.If less than 30 you have to put comment upon the table.You can group similar species together to increase the numbers e.g. salmonella or shigella species.

Distribution Formats: In easy accessible formats to all prescribing Physicians, Infection control staffs, Pharmacists, Epidemiologists & Microbiology Staffs:-Small cards in coat pocketOr in laminated sheets.In the institution website (Intranet). As application or PDF.Printed formats especially in special areas like ICUs.

Antibiogram cards

Antibiogram laminated sheet

Antibiogram laminated sheet GP & Anaer.

Antibiogram laminated sheet GN

Methods of calculations:1- Confidence Intervals (CI): it gives the precision of susceptibility % and depends upon the numbers of isolates.2- Statistical Significance of Changes in Susceptibility Rates: use Chi-square test to compare different S% in different years. A P value of 0.05 is accepted for being significantly different.

Limitations of Data, Data Analysis, and Data PresentationCulturing Practices: sample collection, transport and storage. Bias in treatment e.g. in OPD, change in culturing technique in the lab.Influence of Small Numbers of Isolates: number of isolates to be > 30.

Antibiogram Limitations: 1. Minimum inhibitory concentrations (MICs) are not included; as a result subtle trends below the resistance threshold (known as MIC creep) are not reflected. 2. Data do not take into account patient factors such as history of infection or past antimicrobial use. Resistance patterns for certain drugs vary significantly by age, and a patients underlying medical condition may affect how well an antimicrobial works

3. Data are the result of single organism-antimicrobial combinations, therefore do not show trends in cross-resistance of an organism to other drugs, nor do they reveal synergistic properties of antimicrobials used in combination. 4. Data may not be generalizable to specific patient populations or locations of a healthcare facility if the antibiogram is compiled using hospital- or healthcare system-wide data.

Examples of Accepted Antibiogram (KSH)

KSH

KKHK

Iman

(Iman)

Defective Antibiograms

No Comments!!!!!

Graphs not from our hospitals Klebsiella - Percentage of sensitive Isolates (178).

Pseudomonas Aeruginosa - Percentage of sensitive Isolates (127).

Acinaetobacter - Percentage of sensitive Isolates(20).

Staph.aureus - Percentage of sensitive Isolates (67).

References CLSI. Analysis and Presentation of Cumulative Antimicrobial Susceptibility Test Data; Approved GuidelineThird Edition. CLSI document M39-A3. Wayne, PA: Clinical and Laboratory Standards Institute; 2012.King Fahd Medical City Antibiograms.King Khaled Hospital Hafr Al-Baten

Thank you