New testing method helps earlier diagnosis of STDs

DNA and RNA testing methods make it easier

to detect sexually transmitted diseases earlier.

by Ann Bucy

SBJ Contributing Writer

It's a disease that most people don't want to talk about. But, according to health care professionals, it is also a national health problem that too often goes undetected because people don't get tested.

However, new testing methods are making it easier than ever before to detect the disease.

It is chlamydia, a sexually transmitted disease that can cause complications as serious as sterility, blindness, glaucoma, community-acquired pneumonia and an increased risk of contracting the human immunodeficiency virus (HIV).

The Centers for Disease Control report that 70 percent of women with chlamydia are asymptomatic: they show no symptoms and so don't realize they are infected. As a result, they harbor and spread the disease.

The CDC recommends that all women ages 15-25 who are sexually active or who have changed partners in the last three to six months be tested annually.

And while men are more likely to show symptoms of the disease and seek treatment, sexually active men may want to consider testing for earlier detection.

"In 1995, a CDC survey indicated the Midwest showed the highest incidence of chlamydia. We can now feel more confident in detecting the disease early so that patients can be treated, so we can reduce the amount of complications and the spread of the disease," said Kathy Myers, a medical technologist in St. John's microbiology department.

In her work at St. John's, Myers is using new DNA and RNA testing procedures that are improving the ability to detect infectious agents such as those that lead to chlamydia and HIV, the virus that causes AIDS.

Previous procedures required 10,000 organisms to detect an infection. With DNA amplification, an infection can be detected with only 5 organisms.

The specific testing procedures are called the Polymerase Chain Reaction (PCR) and the Ligase Chain Reaction (LCR).

The procedures work by using a series of heating and cooling cycles to separate DNA or RNA strands of an infectious agent.

"The PCR is used to detect the HIV viral load. Viral load is how much virus is in a patient's system," Myers said. "We count how much is in there. We monitor the quantity of viral particles in their system."

The LCR helps detect chlamydia and gonorrhea, another type of sexually transmitted disease.

These are detected with the help of a machine called the thermacycler.

"The thermacycler works as a heating element and heats up and cools down in a specific time frame," Myers said. "The process takes about an hour and a half. Prior to the thermacycler, the process had to be done manually, which could take several days."

At St. John's, prior to the PCR and LCR, it was necessary to take a pelvic exam and obtain a cervical swab from the patient.

Now the test can be done with a urine specimen.

Sue Watkins, the administrative director of lab services at Cox Health Systems, says Cox will continue to use the pelvic exam for its specimens.

"We use the same tests (the PCR

and LCR), but have a different methodology," she said. There are no immediate plans to switch to the urine-specimen method.

At Columbia Hospitals, Dwight Lindsay, the head of the microbiology department, uses the LCR but not the PCR. "We use either the pelvic swab or the urine sample," he said. "It depends on what the physician wants."

Myers said she was excited about the new technology for several reasons:

First, "We're keeping our facility updated, and the new equipment is helping us have a better handle on a national health problem," she said.

Also, "We're bringing tests online that will more accurately bring the answers the doctors need," Myers added.

And finally, "It will eliminate health risks down the road, too," she said.

PHOTO CAPTION:

Medical technologist Kathy Myers, of St. John's microbiology department, said DNA and RNA testing procedures can aid early detection of such diseases as chlamydia. [[In-content Ad]]