What does microbial contamination have to do with inventory levels? Those of you whose company tests its products, either finished or in-process, for microorganisms, already know the answer: QC hold.

By Amanda Turton

Why haven't more companies been able to reduce their inventory burden? It may be that these companies are treating the symptoms (i.e., high inventory levels) rather than the cause. As Robert A. Stahl points out, inventory accumulates because something in the manufacturing or distribution process allows it to.2 Manage things that cause inventory levels to rise, he advises, and your inventory levels will return to good health. One often overlooked cause of symptomatic inventory accumulation is microbial contamination.


New advances in QC (quality control) testing
Traditional microbial testing methods require incubation periods up to seven days in order to culture the microorganisms to a level that can be detected by eye. New technological advances now make it possible for microorganisms to be detected in 24 to 48 hours, thereby providing a level of sensitivity equivalent to traditional seven-day tests. These rapid test methods can be used for almost any product in which microorganisms might be found. Therefore, they are suitable for testing pharmaceuticals, food, drinks, dairy, beverages and personal care products. In fact, rapid test systems are currently being used in all these industries and implemented in laboratories around the world, resulting in operational efficiencies that are adding millions of dollars to the bottom line.

These dramatic reductions in testing times have been achieved by using a successful new, rapid method — a technology known as ATP bioluminescence. ATP bioluminescence is most commonly seen in the flash of a firefly tail. Put simply, every living organism contains as its basic unit of stored energy adenosine triphosphate (ATP). In the firefly, ATP fuels the reaction to produce light from the chemical luciferin catalyzed by the enzyme luciferase. Since ATP is also present in all living microorganisms, the same reaction can be used to detect the presence of contamination in the manufacturing environment.


ATP bioluminescence products
There are two types of methods using this technology: detection and enumeration. In many industries the very nature of the manufacturing process provides finished products that are "sterile." Even though sterility is not a requirement, the finished product, in most cases, is microbially "clean" (i.e., has no contamination), and a simple rapid screening test can prove this. This is the detection method, which uses a light measurement instrument called a luminometer to do all the work. The process begins with a short incubation period. The sample is then loaded into the luminometer which injects the reagents. A few minutes later, test results deem whether the sample has positive or negative contamination.

Products that most often have a microbial count, e.g., raw materials and process waters, can be tested using the enumeration method to determine whether their microbial loads are within the QC specifications. The sample is filtered, incubated and then loaded into a microplate luminometer, where four samples are processed simultaneously in a matter of minutes. A printout of the results details the number and location of individual microorganisms which can then be subsequently identified, if so desired.

In each case the results generated by the luminometer can be downloaded either into an electronic spreadsheet or into a laboratory information management system (LIMS) for greater efficiency and better management of data. This automation of data collection can provide substantial improvements in the accuracy and timely collection of QC results, thereby providing better workflow in the laboratory while removing subjective, operator-dependent data. The information generated can be used by a remote operator to release products for trend analysis and reporting, or simply archived for later use.


Making the production process more efficient
An overriding goal of any company commonly involves the desire to provide value to its customers by making available products for when they are required, while ensuring that they are safe and healthy to use. The manufacturing process for these products can extend anywhere from one day to several days, depending on the specific organization structure of the company and the nature of the product being manufactured. Whatever the circumstances of the manufacturing arrangement, the basic process remains the same: Raw materials will pass through a supply chain, gaining value incrementally at each stage of production. This is sometimes referred to as a value chain. The value of this in-process inventory is often referred to as "inventory at risk" (i.e., product that may have to be scrapped or salvaged if adverse QC results are reported). Products, whether they be work-in-progress (WIP) or finished goods that are quarantined pending QC results, cease to gain incremental value and can even be considered a financial liability because they reduce manufacturing flexibility and tie up capital. Their true worth will not be realized until a deposition is made by the QC laboratory regarding their microbial status. Both situations are therefore less than ideal.

If products are manufactured during the course of one day, then the QC testing scenario could look similar to that illustrated in Figure 1. This is the best case situation for both the traditional and the rapid test method. If, however, manufacturing is spread out through batch production over several days, then the value of having a rapid test method will greatly increase. This is due to the reduction in inventory at risk, since out-of-specification test results will be known sooner, allowing faster remedial action to be taken and intercepting the further processing of materials along the value chain.

The benefits of a rapid QC result
There are many benefits that result from a more rapid QC test method, some of these are immediately quantifiable, and others result from a corollary effect after the initial benefits are realized.

The most significant benefit that is currently being realized by companies in a variety of industrial sectors worldwide is the reduction in finished goods inventory permitted by a rapid test method. In many cases the elimination of finished goods inventory not only frees up capital to be invested elsewhere in more profitable opportunities, but also allows revenues to flow in sooner, dramatically improving cash flow, the cornerstone of business prosperity.


Contamination Incidents
Closing a production line because of suspected contamination is one of the most damaging occurrences for any manufacturing operation. Each day of downtime can run into thousands, if not millions, of dollars in lost sales revenues. Worse still, if contaminated product reaches the marketplace the company will have to face additional, potentially expensive, costs related to a product recall as well as to brand reputation.

Here, the benefits of a rapid test method should be obvious. A timely result enables deviations in the quality of a process water system to be identified in time to take quick remedial action before materials continue to be processed along the supply chain. This immediately reduces inventory at risk and saves time and money in having to salvage and rework product that has been manufactured from contaminated materials. Also, a line that has been shut down can become operational sooner, thereby allowing a resumption in the generation of revenues and, more importantly, products can be safely released into the marketplace with the knowledge that they are free from contamination.


Efficiency of the QC department
The QC department provides customer service to many other departments in the organization, including operations, regulatory affairs, commercial and technical, as well as to external distributors and retailers. A rapid test method system allows the QC department to improve service to all its customers.

A current proponent of the technology in the pharmaceutical sector reports that the introduction of a new rapid test system has enabled the company to improve its response time for meeting delivery schedules to distributors from 44 percent to 98 percent. This improvement has affected the distribution chain, as distributors are no longer required to carry stock themselves — a result of the new Just-in-Time (JIT) delivery capability of the manufacturer.

When this technology was costed against a product line at one manufacturing facility, the payback on the investment was less than nine months. The company is now planning to implement the rapid test system globally.

According to Patricia Palmieri, group leader, Microbiology, of Chesebrough Pond's Research and Development, "The rapid test method system decreases to 26 hours the time between submission to the lab and release of the raw material or finished product. Incoming raw materials are screened more quickly and finished goods do not have to be held for days in warehousing awaiting microbial clearance."

The technology also provides additional efficiencies. A time and motion study carried out by another pharmaceutical manufacturer demonstrated a 20 percent labor efficiency in the laboratory simply by automating the reading and recording of results. Another case study provided information that savings of $30,000 per annum on one product line could be realized by just reducing the number of tests conducted on a finished product from five to one; since the product was typically uncontaminated, only one test was required to prove the absence of microorganisms.

Those QC laboratory managers that previously complained about the amount of revalidation work required to implement a new method are starting to come around when presented with the larger picture. The trade-off for an initial period of additional work is the longer-term benefits associated with labor efficiencies — less testing and better customer service. All of the rapid test method systems are accompanied by extensive validation documentation in line with the expectations of industry regulators, as well as implementation support and services. No longer does the QC department need to be considered the bottleneck in operational efficiency.

Rapid QC test systems have been conspicuously missing in the laboratories of consumer goods manufacturers for so long that the expectation was starting to fade. Some industries, notably food and beverage, have experimented with available systems and, in many cases, been disappointed with sensitivity and reliability of results. New technological advances have provided a new generation of rapid test systems that provide equivalent, accurate and consistent results in at least one-third of the time of traditional, culture-based methods. These results can be depended on to enable efficiencies in many areas of the organization, particularly in improving manufacturing flexibility, and are a real option for reducing inventory levels.


References
1. APICS — The Performance Advantage, April 1997, p.14
2. APICS — The Performance Advantage, April 1997, pp. 34-38

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