Wednesday, October 16, 2013

Control Procedures in Clinical Microbiology Laboratory

Remedial action to be taken when calibration or control results fail to meet the laboratory's criteria for acceptability.
-Limitations in methodologies, including interfering substances
Reference or normal ranges
-Imminent life-threatening laboratory results or panic (critical values. Must be informed at once by telephone to doctor e.g. Meningococci in direct gram of CSF.
-Pertinent literature references
Appropriate criteria for specimen storage and preservation to ensure specimen integrity until testing is completed.
The laboratory's system for reporting patient results including, when appropriate, the protocol for reporting panic values. Description of the steps to be taken in the event that a test system becomes inoperable. Criteria for the referral of specimens including procedures for specimen submission and handling
Establishment and Verification of Method Performance Specifications
Prior to beginning to report patient results, the laboratory must establish and verify (for all tests and methods) performance specifications, including -----Accuracy Precision/Analytical Sensitivity Analytical Specificity
-If applicable, the laboratory must also verify the reportable range of patient results as well as the reference (normal) range.
-When a new procedure is implemented, the laboratory must demonstrate, prior to reporting patient results, that it can obtain the performance specifications comparable to the manufacturer's established specifications.
-The laboratory must also verify the manufacturer's reference range for the laboratory's population. The laboratory must then establish calibration and quality control procedures based on the verified performance specifications. Each step must be documented in the laboratory's records.
Equipment Maintenance and Function Checks
The laboratory is required to perform equipment maintenance and function checks (electronic, mechanical and operational). These checks are considered to be necessary for proper test performance and result reporting to assure accurate and reliable test results and reports. The requirements for systems approved by the FDA include maintenance performance as specified by the manufacturer and with at least the frequency specified by the manufacturer. All maintenance performed by the laboratory should be documented. The same applies to system function checks - follow the manufacturer's instructions for both the checks and frequency and document each step
Calibration and Calibration Verification
The laboratory is required to substantiate the continued accuracy of each of its test methods, throughout its reportable range for patients, through calibration and calibration verifications
The reportable range of patient test results is the range of testresult values over which the laboratory can establish or verify the accuracy of the instrument, kit or test system measurement response.
Calibration is the process of testing and adjusting an instrument, kit or test system to provide a known relationship between the measurement response and the value of the substance that is being measured by the test procedure
Calibration verification is the assaying of calibration materials in the same manner as patient samples to confirm that the calibration of the instrument, kit or test system has remained stable throughout the laboratory's reportable range for patient test results.
The manufacturer's instructions should be followed, along with using the materials specified by the manufacturer. Each step should be documented
Control Procedures
On a routine basis, the laboratory must perform control procedures to monitor the stability of the methods or systems utilized by the laboratory. Control and calibration materials indirectly assess the accuracy and precision of patient test results. At a minimum, the manufacturer's instructions are to be followed. The laboratory must:
Test quality control samples in the same fashion as patient specimens
Determine the statistical parameters (e.g., mean , standard deviation) for each lot number through repetitive testing. The stated values of an assayed control material may be used as the target values provided the stated values correspond to the methodology and instrumentation employed by the laboratory and are verified by the laboratory
Accept control results only when the laboratory's criteria for acceptability is met.
• Conduct reagent and supply checks for each shipment or batch of reagents, discs, stains, antiserum and identification system when opened. The checks should include positive and negative reactivity, as well as graded reactivity, if applicable. The laboratory must test staining material each day of use to ensure predicted staining characteristics
• For microbiology media, the laboratory must check for sterility, ability to support growth and, as applicable, selectivity/inhibition and/or biochemical response. The laboratory may use the manufacturer's control checks provided the manufacturer's checks meet the National Committee for Clinical Laboratory Standards (NCCLS) for media quality control.
• Document the physical characteristics of the media to confirm that the media has not been compromised. Report deterioration to the manufacturer.
• Follow the manufacturer's specifications for using the media.
Remedial Actions
• The laboratory must establish policies and procedures for remedial actions for quality control failures and apply them as needed to maintain accurate and reliable patient test results and reports. The laboratory must document when
• Test systems do not meet the established performance specifications. Examples include when equipment or methodologies perform outside established parameters and when patient results are outside of the reportable range
• Control or calibration results fail to meet established criteria. When this occurs, patient results tested between the previous acceptable and the current unacceptable run must be evaluated to determine if the patient results had been affected. The laboratory must take remedial action to ensure the reporting of accurate and reliable results. The laboratory cannot report patient test results within its regular time frames. The laboratory must determine (based on the urgency of the tests requested) the need to notify the appropriate individual of the delay.
• Errors are detected in reported patient test results.
o The laboratory must promptly notify the authorized person ordering the test or the individual utilizing the test results.
o The laboratory must issue corrected reports promptly to the authorized person ordering the test or the individual utilizing the test results.
o The laboratory must maintain exact duplicates of the original and corrected report for two years.
Specialty/Subspecialty Requirements
Along with meeting the general requirements, laboratories must also meet the following specialty/subspecialty requirements
Bacteriological laboratories Specific Precautions
The laboratory must check positive and negative reactivity with control organisms:
• Each day of use for catalase, coagulase, beta-lactamase and oxidase reagents and DNA probes.
• Each week of use for Gram and acid-fast stains, bacitracin, optochin, ONPG, X and V discs or strips.
• Each month of use for antisera.
• Each week of use for X V discs or strips (with a positive control organism).
• Each new batch of media and each lot of antimicrobial discs before or concurrent with the initial use, using approved reference organisms. Zone sizes or minimum inhibitory concentration for reference organisms must be within established limits prior to reporting patient results. Each day of use, test appropriate control organisms to check the procedure.

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