CMS SOM App. C, Tag D5485

(h) If control materials are not available, the laboratory must have an alternative

mechanism to detect immediate errors and monitor test system performance over

time. The performance of alternative control procedures must be documented.

Interpretive Guidelines §493.1256(h)

Laboratories may choose to split samples for testing by another method or in another

laboratory to evaluate the results obtained. Previously tested patient specimens (include

specimens across the reportable range) must be tested in duplicate. Precision is

determined through replicate testing of a previously tested patient specimen. The

duplicate tests may be performed by the same individual or by different people and the

results compared to previously defined acceptable limits for differences between

duplicates.

Public Health Laboratories Performing Newly Developed Assays/Test Systems for

Agents for Emergent Public Health Significance

Screening and confirmation methods for agents of emergent public health significance

require the rapid development and transfer of technology and expertise from federal

agencies to public health laboratories (or other designee laboratories). CMS may, as

needed, issue guidance regarding emergent public health issues (refer to CLIA website or

contact CMS for any applicable guidance). Because of unique situations of emergent

diseases or other public health threats, control and calibration materials for the assay or

test system may not be immediately available. Under these circumstances, the laboratory

must follow the assay or test system’s protocol(s) without modification and document

the alternative control procedures employed to ensure accurate test results. Laboratories

are encouraged to use multiple alternative control procedures (as described below) for

ensuring accuracy.

When control and calibration materials are not available, examples of alternative control

procedures that may be available include, but are not limited to, the following:

• Split specimens for testing by another method or in another laboratory;

• Include previously tested patient specimens (both positive and negative) tested in

duplicate as surrogate controls;

• Test each patient specimen in duplicate;

• Test multiple specimen types from the same patient (e.g., saliva, urine, serum);

• Perform serial dilutions of positive specimens to confirm positive reactions;

• Provide additional supervisory review of results prior to release.

In the unique case of PPM procedures, examples of alternative control procedures might

include but are not limited to:

• Two testing personnel, qualified in accordance with 42 CFR § 493.1363, who

are reviewing the same slide, or

• Ensuring that reference slides or pictograms are available, that testing

personnel have demonstrated competency at using materials, and that testing

personnel use established procedures for equipment maintenance and function

checks.

As soon as control and calibration materials become available, the applicable

requirements in §493.1256 must be met.

For specific information regarding testing for agents of emergent public health

significance and alternative methods/procedures for ensuring accuracy of this testing,

refer to http://www.aphl.org/.

Probes §493.1256(h)

If control materials are not provided by the manufacturer, how does the laboratory ensure

the validity of test results?

§493.1261 Standard: Bacteriology.

(Rev. 233; Issued: 09-12-25; Effective: 09-12-25; Implementation: 09-12-25)

(a) The laboratory must check the following for positive and negative reactivity

using control organisms:

Interpretive Guidelines §493.1261(a)

When condition-level deficiencies in Bacteriology are in any or all phases of testing, use

D5002.

For direct antigen systems, laboratories may use bacterial cell suspensions to meet the

requirement for control organisms since the cell suspensions are subjected to both the

extraction and reaction phases of the test. However, a matrix similar to patient specimens

is preferred. For example, for direct antigen tests for group A streptococcal antigen,

already prepared, dried (solid-shafted) swabs, one containing group A streptococcus

(S. pyogenes) as a positive control and another with non-group A streptococcus and/or

Staphylococcus aureus as a negative control may be used. Use D5449 to cite a laboratory

that fails both a negative and positive control. Use D5453 for deficiencies related to the

extraction process.

Additionally, if the manufacturer’s instructions do not specify what the positive control

contains, the laboratory should contact the manufacturer to ensure that the positive

control contains a cell suspension of the organism. Otherwise, the laboratory must have

an alternative control procedure for meeting this requirement (e.g., laboratory suspension

stock ATCC organism, commercially prepared organism controls).

For microbial identification systems utilizing two or more substrates, the laboratory must

check each media using control organisms to verify positive and negative reactivity of

each substrate. Use D5471 for deficiencies in this area.

If a laboratory utilizes primary isolation media (e.g., MacConkey, CLED, EMB, DTM),

for presumptive identification of organisms, then the media should meet the quality

control requirements at D5471 and D5477.

For bacitracin, catalase, coagulase plasma, desoxycholate, oxidase, optochin, PYR disks,

spot indole, staphylococcal latex reagents, streptococcal latex grouping reagents, and X

and V factor strips and disks, use D5471.

For bacteriology, XV discs or strips need only be checked with an organism that

produces a positive reaction. Use D5471.

For guidelines for molecular amplification testing, use D5455.