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Media quality control: an unnecessary evil.

Something has to give when microbiology supervisors are asked to process an increasing number of tests without additional staff. We obviously must consider whether any of our current protocols are disposable.

Doing exactly that, we concluded that quality reassurance of already controlled commercial media is an unnecessary evil in our laboratories. Such repeat testing is superfluous as well as costly.

Heresy? Not at all. Combined data from our three laboratories and four more in the area showed that the quality of the culture media we purchased was consistently high. If laboratory regulators ultimately accept such data, we can redirect our energies to more cost-effective microbiology activities.

We were not the first to recognize that media quality control testing is less than cost-effective. Dr. Raymond C. Bartlett and others reached the same verdict after reviewing their own data. To validate these observations, Bartlett called for more evaluations in the field. Hence, our study.

Because commercially prepared media have become so price-competitive and so widely available, most laboratories use such plates and reagents. The manufacturers perform extensive quality control, a point we confirmed on a visit to the Oregon plant that makes most of the media used in our laboratories.

We got a close look at the documentation and care devoted to each batch and lot of prepared media. The thorough and meticulous quality control porocedures--insured by the extensive inspections of several regulatory agencies--were impressive. For example, the firm routinely performs 16 separate QC checks for its hundreds of different types of media. And this is just the basic approach to quality control. New products receive even more stringent monitoring; media with additives go through additional checks.

Yet the 1967 Clinical Laboratory Improvement Act guidelines and Health Care Financing Administration modifications mandate that microbiologists completely rechallenge each lot of prepared media with organisms of known reactivity. Fortunately, the resulting reams of quality control data can now justify discontinuing a wasteful laboratory procedure.

We knew our media had performed flawlessly for years. But data from individual laboratories won't convince the regulatory agencies. That's why we took a broader approach and asked microbiology supervisors at several area laboratories to compile quality control statistics for the most commonly used isolation media. The seven facilities participating in our study included five hospitals ranging from 25 to 225 beds and two clinic laboratories.

Each microbiology supervisor decided how limited or extensive a record search was needed. Some came up with data on hundreds of quality control tests, representing a few months of monitoring. Others had QC log sheets documenting years of media quality control.

The seven laboratories purchased their prepared media from major biological supply houses specializing in such products. When the labs made their own media from commercial dehydrated bases, they meticulously followed the manufacturers' instructions for rehydration, sterilization, and storage.

To keep the volume of data manageable, we did not list media used infrequently and purchased in small batches. Nor did we include products used by only some of the seven laboratories.

As we expected, all 4,384 lots of media tested performed as promised (Figure I). "Failures" were defined as instances in which the control organisms failed to yield satisfactory results on the media. Examples would be Thayer-Martin media that didn't support the growth of Neisseria gonorrhoeae or led to overgrowth of coliforms.

In an initial scan of our records, we all encountered apparent failures. However, careful examination following retesting of the same lots with new challenge organisms disclosed that these were not true media defects. The most common culprits: stock organisms that failed to grow, contaminated stocks, and organisms transferred to the wrong side of a biplate under a "pseudonym."

Quality control functions can consume a significant amount of laboratory effort and dollars. Bartlett found QC in various hospital and clinic laboratories accounting for 1 to 15 per cent of total work time. Larger laboratories, testing larger batches, spent the least proportion of time on QC; smaller laboratories like our own spent the most. Bartlett also pointed out that many types of media were very reliable. Indeed, his own lab found few deficiencies.

The laboratories in our study carefully adhered to guidelines established by the College of American Pathologists, the Joint Commission on Accreditation of Hospitals, and Medicare. This entailed testing each batch and lot of media with multiple challenges by known organisms of positive and negative reactivity or growth characteristics. The checks covered some 50 different types of media as often as once or twice a week. Even though we had streamlined our quality control procedures a few years ago, we still suspected our costs for media QC were very high.

To probe costs, the authors amassed a month's worth of data from their three hospital laboratories. We tabulated invoice prices for each plate or tube used in QC. Then we added in the cost of technologist time, based on actual minutes or CAP workload units allotted for each of the functions.

For example, transfer of a stock organism to a single plate required 2.5 CAP units. At one institution, technologist pay averaged $14 per hour or 23.3 cents per minute, including benefits. That spelled a costs of 58.3 cents (2.5 X 23.3 cents) to test one plate with one organism or to subculture one stock to one plate. More time went into processing and reporting--7.8 CAP units or $1.81 per quality control procedure.

The basic monthly QC costs for the three hospitals are itemized in Figure II. Remember, these are just the minimum costs. Other charges, much harder to calculate, no doubt significantly inflate these figures. Consider such cost factors as gas generating systems, enclosures, and anaerobic indicators; carbon dioxide tanks; identification reagents; biochemical batteries for speciating test organisms for use on other media; lyophilized stock cultures or stabilized patient-originated organisms; freezer vials and holding media; paper and notebooks for data storage; and review time by technologists, supervisors, and pathologists.

Even without these hidden costs, the three laboratories spent a total of more than $750 for just one month of repeat quality assurance with control organisms. And they did not produce any new or relevant data for that $750.

Media quality control also creates uncessary problems for busy laboratories. We diagnosed six significant QC headaches in our laboratories:

1. Inadequate refrigerator and incubator space. Equipment and space restrictions limited the size of the batches or media lots we could store. Thus we couldn't buy in bulk and consolidate our media QC.

2. Media outdates. Although it's possible to complete QC testing for most organisms before running patient tests, certain slow-growing organisms--mycobacteria, for example--and some fungi create special problems for smaller laboratories. To avert outdates of such isolation media as Lowenstein-Jensen agar and Mycobactosel, we often must use an entire lot for patient testing before stock cultures grow enough to define media quality.

3. Stock organism subcultures. We sometimes spend a surprising amount of time and money subculturing stock organisms. One of the labs in our study subcultures no fewer than 23 different stock organisms each week to control all media and reagent functions. The technologist cost alone for this exercise is almost $70 per month. Outlays for media to store and subculture these organisms bring the total expense to nearly $100.

4. Maintaining fastidious microorganisms. Culturing Legionella pneumophila, such strict anaerobes as Clostridium novyi, and such organisms as Neisseria gonorrhoeae that require multiple maintenance transfers interferes with smooth lab operations. Organism stocks that die on transfer are not uncommon--and neither are the resulting replacement searches and viability subcultures.

5. The "aka" (also-known-as) syndrome. Despite careful subculturing, we have all made the frustrating discovery that our known control has migrated to the other side of a biplate and become "something else." When this happens, we lose additional time and effort providing the proper control results.

6. Obtaining valid organisms. Laboratories with inadequate in-house supplies of fastidious microorganisms often run into high expense procuring commercial stocks. Though convenient, these reagents carry their own special problems. For example, some lyophilized strains--most notably, Proteus vulgaris ATCC 13315--do not produce uniform reactions with certain biochemical tests, due to their slow rate of growth. When we tested an enteric strip, we consistently achieved the expected reactions in the cupules with patient-originated Klebsiella pneumoniae. The ATCC-lyophilized stock, however, was inconsistently positive for urea and citrate. To reduce repeat control testing of the strip, we had to substitute patient-originated organisms.

In order to use these organisms for subsequent tests, we had to abandon our usual protocol and then document our reasons for doing so. Each major departure from approved protocol--organism substitution, for example--requires us to revise our manuals, change the log forms, obtain management's approval, and take the time to inform staff members of the updated procedures.

Many microbiologists would like to eliminate the waste in quality control testing, but they fear getting bad marks from accrediting agency inspectors. The rules governing media QC have been widely interpreted by inspectors and their agencies.

Some inspectors agree that the commercial suppliers' quality control is more than sufficient and are working toward relaxing these restrictions. Others, however, take a worst-case attitude: If anything can go wrong, it will. Therefore, every lab must completely reverify the quality of a product, even if it has only been carried across the street. Complying with this ultra-conservative approach and supplying documentation takes a Herculean effort.

Laboratory directors and staff members should try to determine exactly how each agency officially interprets the rules. Say, for example, that the questionnaire simply asks: "Is media quality controlled?" Does this mean the manufacturers quality control is acceptable? Or must we assume that recipient laboratories are obligated to retest the media?

We have decided that the responsibility rightly rests with the manufacturers of microbiology reagents and media. Once limited in-laboratory testing demonstrates a product's reliability, then retesting serves no useful purpose. The manufacturers are liable for their products, and we must trust them not to release bad lots. Otherwise, we have to find other suppliers.

It's essential that we communicate with the inspectors and remember that both sides want to do what is right and reasonable. Certainly, microbiologists must observe specified outdates and proper storage and handling, and also note whether the media arrive in good condition.

and lest we forget microbiologists do use backup systems. We set up multiple plates and pieces of media on every specimen, with each setup and initial Gram stain as a check and balance. We are not advocating elimination of quality control in laboratory medicine. However, every laboratory dollar and working hour must be carefully weighed in terms of cost accountability. Why not give ourselves a break and let reputable suppliers insure--through continued rigid testing--that their products will perform as described in the package insert?

If we adopt this approach, we can use our vaulable quality assurance time to tackle these concerns:

* Specimen quality. Insuring the quality of specimens submitted to the laboratory is of paramount importance. It is essential that competent microbiologists screen specimens by Gram stain and gross evaluation. We should reject poorly collected or mishandled specimens and request a repeat. Reports generated on inadequate specimens do not provide relevant microbiological data and can be misleading to clinicians.

* Research and development. New procedures--tissue cultures for herpes and Chlamydia, for example--now fall within the realm of testing in smaller labs. We must find time to train technologists and develop these new systems.

* In-house education. Labroatory technology is advancing so rapidly that laboratorians need ongoing in-service sessions. With travel budgets severely reduced, renting or purchasing some of the excellent educational programs or slides available for laboratory use can stretch continuing education dollars and build technologists confidence and expertise.

Physicians in emergency rooms and clinics often can benefit from technologists' expertise to learn more productive methods for diagnostic determinations. For example, they can be taught to read plates and direct Gram stains.

* Controlling the entire system. Many laboratorians stress the need to monitor the entire system. Handling internal unknowns the same way as actual patient cultures takes time, but this offers an exceedingly valuable check for the entire system.

In addition, having several individuals proofread reports for clerical errors is important even in small laboratories. Too often, this elementary double check falls by the wayside in favor of media quality control.

Media QC overkill serves no useful purpose in the professionally staffed clinical laboratory. Eliminating this unnecessary function will extend our limited resources to cover worthwhile quality assurance programs.

We encourage all microbiologists to evaluate their own quality control programs. Together, we may be able to convince accrediting agencies that our quality assurance budgets can be better directed to improve patient care and reduce patient costs.
COPYRIGHT 1984 Nelson Publishing
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Author:Harris, Patricia C.; Sealey, Lynn B.; Pitman, Barbara
Publication:Medical Laboratory Observer
Date:Feb 1, 1984
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