Southern Nevada Public Health Lab Gears Up For Bioterrorism

Fri, 12/01/2006 - 3:00am
Sharon JohnsonMary Coulombe

Avian Flu. West Nile Virus. Mad Cow Disease. SARS. Anthrax. Thoughts of these deadly pandemics are enough to keep anyone up at night, but for scientists at the Southern Nevada Public Health Lab (SNPHL), they come with the job. This laboratory, like other public health laboratories, is on the front lines when it comes to identifying and diagnosing the sources of disease outbreaks and bioterrorism attacks, and this is critical in directing an appropriate response. Given the hustle and bustle of tourism-heavy Las Vegas, with more than 37 million visitors each year, the threat is very real. As public nervousness about potential pandemics grows, pressure on public health labs intensifies. This is not to say that SNPHL ever took its role lightly.

Since its creation in 2003, the facility has always maintained a stringent focus on quality control. Due to what would be fatal consequences in the case of errors in its liquid handling operations, such as missing the source of a deadly Norovirus outbreak (the disease that made headlines during several high-profile cruise ship incidents) or wasting precious time by causing investigators to trail the wrong source of a bioterrorist attack, pipette calibration is taken seriously. To strengthen data integrity and enhance personnel technique training, SNPHL decided to implement a liquid delivery quality assurance program based on Ratiometric Photometry, which measures the absorbance of light by two dyes to verify volumes. Highly accurate and precise, even when working with volumes in the micro-liter range, this technology is the foundation of ARTEL’s PCS®(Pipette Calibration System) and MVS®(Multichannel Verification System). These systems provide rapid, on-the-bench pipette performance verification as well as objective assurance of the liquid handling proficiency of individual technicians, facilitating the laboratory’s ability to accurately diagnose threats to public safety.

Many tests performed at SNPHL rely on the
accuracy and precision of liquid
handling instruments.

After 2001, Las Vegas was the only major city without a Laboratory Response Network (LRN) Lab within 100 miles. Started in 1999 by the Centers for Disease Control and Prevention (CDC), this network of facilities was established to improve the nation’s response to biological and chemical terrorism, infectious diseases, and other public health concerns. Put to the test during the anthrax attacks in 2001, this network has grown to include over 140 laboratories.

The federal government’s Department of Homeland Security recognized the public safety threat caused by the Southern Nevada Health District’s lack of a nearby facility capable of identifying biological agents. Through the Defense Appropriations Bill of 2002, funds were directed to set up the Southern Nevada Public Health Lab, which would serve as the area’s LRN lab and provide a branch laboratory of the State Laboratory in Reno, in operation since 1962.

SNPHL was to be designated a Reference Lab (like most public health laboratories in the network), tasked with analyzing samples identified as suspicious by hospital laboratories (Sentinel Labs). To become part of the network, SNPHL had to demonstrate testing accuracy, trained personnel, properly designed facilities, and appropriate equipment. In other words, the laboratory needed to prove its ability to generate quality test results.

The monies set forth by the Department of Homeland Security allowed SNPHL to purchase state-of-the-art laboratory equipment to effectively meet CDC requirements and generate accurate test results. Because testing these samples often requires rapid pipetting of very small volumes, the ability to verify liquid handling instrumentation performance at minute volumes was critical. To calibrate its pipette population consisting of six multichannel and 54 single channel instruments, some contained to cleanroom environments, SNPHL managers sought a pipette calibration solution that was fast, easy to use onsite, and capable of microliter measurement. This led SNPHL to Ratiometric Photometry technology, which measures the absorbance of light by two proprietary colorimetric reagents to combat problems associated with low-volume measurement.

SNPHL must also comply with the Clinical Laboratory Improvement Amendments (CLIA) used to accredit clinical laboratories, which mandates the maintenance of a regular pipette calibration program and documentation of results. Compliance is facilitated by the automated documentation provided by SNPHL’s liquid delivery quality assurance program.

Certification, however, is not a one-shot deal. To maintain its status as a LRN and CLIA-certified lab, SNPHL undergoes continual proficiency testing. During these evaluations, samples assessed by the laboratory are sent out for analysis. The laboratory’s test results are compared against known correct results to verify if its testing mechanisms are accurate and precise. Regular assurance of pipetting technique and objective performance of the pipettes are necessary to meet these standards.

A technician at the Southern Nevada Public Health Laboratory uses ARTEL's PCS to verify the
performance of pipettes.

Given the small window of time allotted for analysis of potentially harmful samples and the irreplaceability of many samples, SNPHL cannot risk incorrect test results.

To illustrate this point, consider the United States Postal Service, a victim of past anthrax attacks. Due to these attacks, the USPS continually monitors its air quality to detect the presence of biological agents. Samples identified as potentially dangerous are sent to LRN labs for analysis and results are expected in four hours. After this time period, the lack of definitive results will cause a media frenzy and spark public anxiety about the potential health crisis.

Having accurate pipettes that you can count on is important for the SNPHL, since the four-hour expected turnaround provides just enough time to complete sample testing. If liquid delivery device performance is questionable, repeat tests would be required, and this would cause delays, panic, and, in the event of a real emergency, loss of precious time. And with real bioterrorism attacks, every minute counts. The longer it takes to identify the presence and cause of an outbreak, the more people fall ill without doctors knowing why. For tourism-dependent Las Vegas, this would be devastating.

Having onsite tools for pipette calibration strengthens SNPHL’s confidence in its pipette-generated data by providing the flexibility to calibrate as needed. Now, SNPHL can conduct interim verification checks between calibration cycles (scheduled every six months) to enhance quality assurance.

Another potential source of error in liquid handling operations is contamination. Given the small volumes characteristic of SNPHL-tested samples, a minute amount of foreign substance can alter test results.

For example, contamination control is critical in performing PCR (Polymerase Chain Reaction) testing, and for LRN labs, the ability to PCR test is necessary. Used to rapidly detect and diagnose infectious diseases, biological agents and other maladies, the PCR test improves responsiveness to biological attacks by providing test results in fewer than four hours, while the traditional method utilizing viral cultures can take three to fourteen days. Because the PCR test amplifies a DNA sequence to detect traces of harmful substances, any bit of contamination present will also be multiplied, and this can cause false positive results.

If SNPHL outsourced pipette calibration, it would need an entire second set of pipettes to rotate in when the original instruments were out of the laboratory. With a number of dedicated-use pipettes, strictly used for one test or one portion of a test to avoid contamination, this would be costly and inefficient. With outsourc-ing, there would also be the concern that the just-serviced pipettes would bring contamination into the PCR laboratory.

SNPHL laboratory technicians can save time if they can keep their PCR pipettes segregated during calibration, so they do not become contaminated. With its in-house liquid delivery quality assurance program, the pipettes taken from the bench for calibration and are back in the laboratory in an hour, ready for use, as opposed to taking days with outsourcing.

Gravimetry, which relies on weighing samples to determine volume, can be used in-house for pipette calibration. However, this method does not perform well at low liquid volumes or in dry environments.

Pipette malfunction and contamination are not the only sources of error in liquid handling processes. Operator technique can seriously impact the accuracy and precision of dispensed volumes, even with a perfectly functioning pipette. For this reason, staff training is required for LRN certification.

At SNPHL, laboratory technologists and technicians are required to calibrate their pipettes at least every six months. Using calibration technologies that provide real-time volumetric measurement makes pipette calibration a learning experience, providing continual, hands-on technique training in the course of normal operations. The speed of the system allows for instant verification of proper technique.

The ability to train SNPHL personnel and new hires on pipet-ting technique and do QA over time so management can see if they have maintained their pipetting technique is an advantage. If there are too many re-dos from a statistical standpoint, then management will sit down and discuss what is occurring and how to improve.

In the Southern Nevada Public Health Laboratory, whose daily operations can directly affect public safety and where wasted time and poor quality can result in lives lost, there is clearly no room for error. With its advanced liquid delivery quality assurance program, SNPHL can rest assured that its liquid handling operations are up to par.

Mary Coulombe is Clinical Sales Manager at ARTEL, responsible for supporting ARTEL’s clinical laboratory customers and has 30 years of experience in the life science industry. Coulombe plays an instrumental role in the company’s provision of liquid delivery quality assurance products and services. She can be contacted at 207-854-0860 or

Sharon Johnson, MSA, MT (ASCP), is Lead Technologist for Bioterrorism and Molecular Testing at the Southern Nevada Public Health Laboratory and has 30 years of laboratory experience both as a technologist and laboratory manager. She can be contacted at 702-759-1020.



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