STDs – Lablogatory

The Law of Unintended Consequences

Has the guidelines that encourage less Pap testing over the course of a woman’s life contributed to less women being screened for STDs such as Chlamydia? According to a study published this week, yes. The cohort is rather small–3000 teenagers and young women–but even so, the results are striking. Before 2009, 30 percent of patients were screened for Chlamydia; after 2009, only 1 percent were.

While this is discouraging, the CDC found that teenagers are having less sex than they were twenty-five years ago, which some attribute to the HPV vaccine and its accompanying education.

Further reading on the relationship between HPV vaccines, Pap screening, and STD testing:

Chicago Tribune

NPR

Healthday

–Kelly Swails, MT(ASCP), is a laboratory professional, recovering microbiologist, and web editor for Lab Medicine.

CDC Recommendations for Laboratory Detection of STDs

Several months ago the CDC updated their recommendations for laboratory detection of Chlamydia trachomatis and Neisseria gonorrhoeae.

A summary:

Chlamydia trachomatis

Swabs must have a plastic or wire shaft and a rayon, Dacron, or cytobrush tip.
Swabs must be inserted 2-3 cm into the male urethral or 1-3 cm into the endocervical canal followed by 2-3 rotations
Specimens should be sent to the laboratory 1) within 24 hours of collection, 2) in sucrose phosphate glutamate buffer or M4 media, and 3) at less than or equal to 4 degrees C

Neisseria gonorrhoeae

Gram stain of male urethral specimen that contains PMS and intracellular Gram-negative diplococcic is considered diagnostic
A negative Gram stain result does NOT rule out infection
Swabs must have a plastic or wire shaft and a rayon, Dacron, or cytobrush tip.
Swabs must be inserted 2-3 cm into the male urethral or 1-3 cm into the endocervical canal followed by 2-3 rotations
For specimen transport, culture transport systems are preferred over swab transport systems
Specimens should be plated and incubated in an increased CO2 environment as soon as possible
Culture media should include selective (such as Thayer-Martin or Martin-Lewis) and nonselective (such as chocolate) agar
Oxidase-positive, Gram-negative diplococcic that grow on selective media can be presumptively identified as N. gonorrhoeae

Nucleic acid amplification tests (NAATs) are superior when compared to other culture and nonculture diagnostic methods for both organisms. However, it’s important that lab professionals understand the limitations of these tests.

Microbiologists should take the time to read the report here.

–Kelly Swails, MT(ASCP), is a laboratory professional, recovering microbiologist, and web editor for Lab Medicine.

Love Is in the Air

And so are STDs.

Well, not the air so much as … other places … but anyway. It’s that time of year again. My personal anecdotal experience is that testing for STDs tends to spike in late winter/early spring (Thanks, Valentine’s Day and Spring Break). Several STDs can make your Valentine’s Day one to remember, though the big three in this country are gonorrhea, Chlamydia, and syphilis. The incidence of these STDs are rising, and the biggest demographic for infections are 15-24 year-olds. (If you want to read the full CDC surveillance report in all its glory, it’s here. Make some popcorn. It’s long.)

What does all of these mean for laboratory professionals? Microbiologists need to be aware that Neisseria gonorrheoeae can grow on blood agar, albeit not as well as it does on chocolate or Thayer-Martin. On blood agar, the colonies are grayish to white and more opaque than those on chocolate agar. The gram stain shows gram-negative diplococci, but as always, a gram stain result should be considered presumptive until confirmed by culture or molecular tests. Laboratories should be aware of their patient demographics; if your lab serves a large population of teenagers and young adults, you might see an influx of specimens.

–Kelly Swails, MT(ASCP), is a laboratory professional, recovering microbiologist, and web editor for Lab Medicine.