| Failure Type | Likely Cause | Corrective Action | | :--- | :--- | :--- | | (No growth of ATCC strain) | Media expired, incubator temp incorrect, or inoculum too light. | Re-test with fresh control. Check incubator temp. Check expiration dates. | | AST Failure (Zone too small) | Bacterial inoculum too heavy (McFarland standard error). | Re-standardize suspension to 0.5 McFarland. Verify turbidity meter. | | Reagent Failure (Oxidase negative on control) | Reagent oxidized/expired. | Discard reagent, open fresh bottle, re-test. | | Contamination | Unsterile technique or environmental contamination. | Sanitize work area. Check biological safety cabinet airflow. |
This phase encompasses the actual "benchwork"—the isolation, identification, and susceptibility testing of organisms. quality control in microbiology slideshare
: Focuses on the "input" variables. This includes the proper collection, labeling, and timely transport of specimens. Experts on Slideshare emphasize that maintaining specimen integrity is crucial, as poor quality at this stage cannot be "fixed" later in the process. | Failure Type | Likely Cause | Corrective
“Quality Control in Microbiology: The Unseen Guardians” Check expiration dates
Chemical reagents degrade over time. QC ensures they are working on the day of use.
Practical Guidance for Clinical Microbiology Laboratories - PMC
In clinical microbiology, the margin for error is effectively zero. A misidentified pathogen or a false susceptibility result does not just represent a laboratory error; it can lead to treatment failure, increased morbidity, or the spread of antimicrobial resistance. Quality Control (QC) in microbiology is the sum of all procedures undertaken to ensure the reliability of laboratory results. Unlike chemistry or hematology, where results are often quantitative numbers, microbiology deals with biological organisms that are inherently variable. Therefore, QC in this discipline requires a unique, rigorous approach.