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Evaluating the new microbiology instruments.

The era of high technology has arrived in the microbiology laboratory. If it was long overdue, it is literally making up for lost time.

For example, enzymatic methods have reduced the wait for identification of some organisms from overnight to four hours. Antimicrobial susceptibility testing methods have shortened the traditional 18- to 24-hour bacterial incubation period to four hours, while enzyme testing for beta lactamase now takes only a few minutes.

As recently as 1975, most serum antimicrobial assays were done by a manual bioassay method that took three hours to set up and required overnight incubation. Then a radioimmunoassay technique reduced the time to one hour--and RIA in turn has lost ground to an enzyme immunoassay method that cuts the time to under 15 minutes.

The number of automated techniques currently applied to microbiology is small, but growing rapidly. Polarizing fluorescence utilizing the principle of fluorescence immunoassay can now accurately determine antibiotic levels in less than two minutes. Radiometric detection of carbon dioxide yields results on most positive blood cultures in 24 to 48 hours.

Other developments include the use of the limulus assay lysate test for endotoxins; measurement of bacterial ATP by bioluminescence; rapid detection of bacterial antigens, toxins, and antibodies by coagglutination techniques and enzyme immunoassay; and rapid identification of bacteria and its products by high-pressure liquid chromatography and head-space chromatography.

These developments are only the beginning. Microbiology is the hottest laboratory area for future technological development. Research is already under way on rapid techniques to identify fungi, bacteria, and viruses using DNA probes.

These technological changes, coupled with increasing cost restraints, force the microbiologist to consider newer methods in strategic planning. This doesn't suggest that we immediately discard our present technology. However, those of us who resist the new technology will watch our laboratories become obsolete. Only by careful planning and evaluation of the newer methods and instrumentation can we effectively manage the clinical laboratory of the future.

One crucial activity in this process is the evaluation and selection of appropriate equipment. During four years of evaluating automated equipment, our 1,200-bed hospital's microbiology department has developed a system that may serve as a useful guide. The steps outlined below should help you avoid major and costly mistakes in capital investment, and prevent needless frustration during the evaluation process.

Preparation. Generally, we make equipment purchase decisions to fulfill a specific laboratory need, arising from increased workload, budgetary projections, clinicians' requests for certain tests, a demand for cost or labor savings, pressure for faster turnaround time, maintenance requirements, or other stimuli.

Whatever the reason, the first step toward instrument purchase is to request literature from various manufacturers and read published studies that evaluate instrument performance. Learn what systems are available. Compare alternative instruments and appraise their features and components, while making an initial cost comparison. Also check the unit value assigned to the procedure or instrument by the College of American Pathologists or the Canadian Workload Measurement System in order to make workload projections.

Next, determine whether the instrument will fulfill your laboratory's needs. Will it provide rapid results? Are the results accurate and reproducible? Does the instrument offer cost savings? Can it handle the projected workload adequately? Some of these questions may be answered by laboratories that have the instrument; ask the salesperson for references.

In-house evaluation. Once you've narrowed your choices by research and comparison, it's imperative to evaluate the instrument in your laboratory to determine overall performance and potential problems. In-house evaluation allows you to assess work flow patterns, staff and supply requirements, and overall impact on the laboratory, technologists, and other hospital areas. Encourage technologists to participate and make suggestions. They must have hands-on experience to provide necessary feedback on the instrument's performance.

During the in-house evaluation, you will be rating the instrument in six performance areas: technical accuracy, equipment specifications, versatility, maintenance needs, costs, and technological impact. Let's take a closer look at each of them.

* Technical accuracy. Results generated by most miocrobiology instruments can be classified into three categories: positive or negative, as in a urine screen for significant bacteriuria; organism identification; or unit values, such as aminoglycoside assay levels.

Each type of instrument must be tested to determine its accuracy, reproducibility, sensitivity, and specificity. A minimum of 100 analyses, using either a variety of specimens or various strains of bacteria, are necessary to create statistically significant data.

Instruments that analyze antibiotic levels may be tested by running a wide range of serum samples spiked with known weight concentrations of antibiotics. Calculate recovery of antibiotics in percentages at the various levels. To determine the instrument's precision and interday and intraday variation, run the analyses in duplicate over a period of five to 10 days. You may use external controls, but check that they cover a range from low to high.

To test instruments that identify or perform susceptibility tests of bacteria, I recommend including several strains from the American Type Culture Collection in Rockville, Md. Smaller labs may have to use a reference laboratory to supply specimens or to test or identify bacterial isolates.

In all cases, check the instrument's results against a standard reference method. Statistical methods such as linear regression analysis, correlation coefficients, and paired t-tests may help you evaluate the data.

* Instrument specifications. All instruments brought into the laboratory--even temporarily for evaluation--should be checked for electrical requirements by the hospital's biomedical or electrical engineer. Apart from the obvious concern about adequate wiring, remember that fire insurance probably won't cover an unapproved instrument.

Make sure the engineer also monitors the voltage fluctuation of the electrical outlet intended for the instrument. Overlooking this precaution can result in many frustrating moments--as we learned when we installed our first large automated instrument.

The unit, designed for rapid testing of antimicrobial susceptibility, gave us unsatisfactory results almost from the beginning. Sometimes results were lost. Computer experts searched through the board for a malfunctioning chip, and we checked every electronic circuit. Finally, after eliminating every other possibility, we thought of the power outlet. When checked, it revealed the problem: intermittent, tremendous power surges.

We solved the problem easily by installing a line stabilizer, a feature built into some new instruments. But a preliminary check for voltage fluctuation would have saved us a lot of time and trouble.

Power shortages or checks when the instrument is running can result in lost data, so be sure you have a backup power system.

One further planning item: Most new instruments have microprocessors or electronic gadgets that require an air-conditioned room to prevent overheating. This is a particular danger in warm climates, or for instruments that run for many hours at a time.

* Versatility. The high capital and overhead expenses of most laboratory instruments make cost justification essential. It's wasteful to use an expensive piece of equipment for only a single laboratory test, no matter how accurate and reproducible the results.

One of our first automated instruments was an RIA system for analysis of antibiotic levels. It could assay two aminoglycosides very accurately. However, physicians at the hospital soon began to ask for levels of other antibiotics. Our choice was to buy another instrument just like the one we had--and eventually find ourselves in the same predicament--or to invest in a more versatile instrument.

The point is that instruments must perform several functions or they will quickly outlive their usefulness. Some automated instruments can now do susceptibility testing, urine screening, and yeast and bacterial identification.

Other aspects of equipment versatility include data management capabilities and the ease of interfacing the instrument with the hospital or laboratory computer. Ask the manufacturer what developments are planned to update and increase the instrument's potential, such as research capabilities or expansion modules.

* Maintenance and service. Check on how much and how often maintenance is required, because this will affect the instrument's total cost. It's worth getting this information in writing since salespeople are often vague about details that may add significantly to your budget later on.

Most manufacturers generally include a year's free service with the purchase of a laboratory instrument. It may seem that your troubles are over for a year, but find out--in writing--precisely what the service contract includes. For example, does it cover labor charges or only parts? Will a local repairman respond to service calls? Do you need to stock important spare parts? What's the average downtime in your part of the country? Will the manufacturer substitute another instrument under any circumstances?

You may also get a rude shock if you fail to find out what a service contract costs after that first free year. An average annual service contract costs 10 per cent of the instrument's total capital cost. When deciding whether the lab can absorb this cost, you may consider waiving the service contract, but it's not advisable. Parts and labor costs for automated computerized instruments can mount up fast, as we found out the year we decided to forgo a service contract on our antibiotic susceptibility instrument.

The instrument gave us few problems during its first year, under the free service contract. At the beginning of the second year, the $15,000 service contract meant the difference between meeting our budget and going over it, so we decided to do without. Within three months, we paid $2,000 to replace some LEDs--and promptly reactivated our service contract.

* Cost analysis. This is the most important aspect of any equipment evaluation. In addition to capital costs, it should include an evaluation of the cost of reagents, disposable supplies, labor, daily quality control, and calibration. The actual cost per test depends on these factors plus your average daily workload. For example, a substantial workload can result in significant cost savings, while a light workload may make an automated method some expensive than the existing manual method. The accompanying Table I illustrates this difference in a hypothetical cost comparison for three antibiotic assay systems. To perform one test, FIA and EIA are less expensive than RIA as a function of technologist time. But with a higher number of tests, RIA becomes more economical than the other two methods.

A complete cost analysis will also include time and motion studies to determine the actual labor costs per test. Compare testing time of an automated procedure and your existing method. If technical time and reagent costs are equal for manual and automated methods, it's unlikely that the instrument will be cost-effective; look for other obvious advantages to make it worthwhile.

Include the projected life of the instrument in cost analyses. Most instruments have an average life span of three to five years. Will yours pay for itself based on your present and projected workload?

Finally, consider various options for instrument acquisition and payment. Rental or lease alternatives can help offset capital and budgetary costs. Some manufacturers will install an instrument at minimal cost if the laboratory buys a certain volume of supplies and reagents per month. This method may include reagent surcharges or higher service contract charges. Its cost-effectiveness will depend on the life of the instrument and the added cost of reagents.

* Technological impact. New automated instruments, especially in microbiology, will inevitably cause change in staffing and work flow patterns, supply costs, storage facilities, technologists' attitudes, and other areas of the clinical laboratory. Evaluate these changes and determine how you will need to accommodate them.

In some cases, education may be the best response. The laboratory must inform and orient clinicians, nursing supervisors, and other personnel to insure adequate communication and feedback during implementation of the new procedure. Perhaps you will even need to redesign floor space for changing work flow patterns.

New technology will have a particularly strong effect on your staff. Technologists often worry that their jobs will be taken over by a machine. Give them every assurance that innovations are important to the future of microbiology and will make their jobs easier and more productive. Technologists will accept change more readily when they feel involved in providing better patient care.

The procedures outlined above should help you make a decision that will satisfy present and future needs. They can be applied to any size or type of laboratory with equal success.

If the new instrument holds down payroll costs, improves efficiency, and increases the lab's capabilities, you will be able to justify it, even with today's tight budgets.
COPYRIGHT 1984 Nelson Publishing
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1984 Gale, Cengage Learning. All rights reserved.

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Author:Ngui-Yen, John H.
Publication:Medical Laboratory Observer
Date:Feb 1, 1984
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