Advances, trends, and what’s needed
By Karen Appold
Screening for sexually transmitted diseases (STDs) is key to bringing this hidden epidemic into the spotlight. It is also the first, critical step for identifying common and costly STDs such as Chlamydia and HIV. “Screening can help detect STDs early on. When combined with treatment, it is one of the most effective tools available to protect a person’s health and prevent transmission,” says Kevin Karem, PhD, chief of the laboratory, reference, and research branch in the division of STD prevention at the US Centers for Disease Control and Prevention’ (CDC), Atlanta.
Beyond identifying infections, STD testing is the cornerstone of monitoring for antimicrobial resistance. “Monitoring is especially pivotal for gonorrhea, which has grown resistant to every drug ever used to treat it, including sulfonamides, penicillin, tetracycline, and, most recently, fluoroquinolones,” Karem says. Facing a shrinking gonorrhea treatment arsenal, CDC revised its gonorrhea treatment guidelines in 2012 to preserve the last available effective treatment option, cephalosporins, for as long as possible. “Health departments and labs must help CDC keep a watchful eye on emerging drug resistance and report any instances to CDC when they occur.”
According to Kelly Wroblewski, MPH, MT(ASCP), director of infectious diseases at the Association of Public Health Laboratories, Silver Spring, Md, “Allowing clinicians to tailor treatment will go a long way in treating individual patients. The key is to develop testing that will identify which drugs will or won’t work well for each patient. This is available now, but in the case of gonorrhea, we still rely on culture—a classical method of microbiology that takes time. Drug-resistance tests are usually conducted only in the case of a treatment failure.” In the future, a molecular assay that targets resistance markers may be very useful to enable clinicians to target gonorrhea treatment.
STD testing advances have the potential to help healthcare providers identify more hidden infections, provide prompt and appropriate treatment and other prevention services, and avoid the consequences of untreated STDs. “Those consequences are particularly serious for young women because they can lead to severe reproductive health complications, such as infertility and ectopic pregnancy,” Karem says.
STD testing advances also play a critical role in expanding the understanding and detection of specific infections and antimicrobial resistance. “Understanding an infection’s susceptibility to certain drugs can guide research for new treatment options, an essential part of helping us to better address this nation’s STD epidemic,“ Karem says.
Rapid point-of-care testing is an important testing advance that allows healthcare providers to diagnose and treat patients in one visit as well as realize cost savings. “More importantly, it can help ensure more expedient treatment for the patient, which can also reduce transmission of the infection in that time period between diagnosis and treatment,” Karem says. “But most importantly, it addresses an even larger public health concern known as ‘losing a patient to follow-up,’ where a patient tests positive but never returns for the treatment. In this scenario, the likelihood of transmission increases and may proliferate an already severe STD burden.”
Wroblewski agrees that rapid point-of-care testing is a huge trend. “We’re looking to see an assay for syphilis soon,” she says. “Use of the HIV point-of-care test is longstanding and well documented. There’s interest in developing it for other assays as well.”
One concern, however, is that sometimes healthcare workers perform point-of care testing even if they haven’t been well trained in it. They may not pay close attention to quality control or quality assurance, or not follow package insert instructions. “This can have a huge impact on patient care and public health,” Wroblewski says. “The lab still needs to have a role in making sure that the individuals conducting the tests are adequately trained.”
Voids in STD Testing
Greater awareness and action is needed at all levels to ensure good health, particularly for those who are disproportionately affected by STDs. “CDC is working to promote STD screening, monitor for microbial resistance, recommend the most effective treatments, and provide resources to state and local health departments to support on-the-ground STD prevention efforts,” Karem reports.
However, CDC is also calling on public and private partners to help develop urgently needed tools such as improved diagnostics. “For example, point-of-care susceptibility tests must be explored to help providers know at the time of diagnosis which drug will be most effective,” Karem says.
Regulatory approval of rapid point-of-care tests is also needed. Currently, there is only one such test for syphilis. “This is particularly concerning given the troubling rise in infections among gay and bisexual men in recent years,” Karem says. Newly released CDC surveillance data for 2012 show that, among men, men who have sex with men accounted for 84% of all cases of primary and secondary syphilis—the most infectious stages of the disease. Without proper treatment, the infection can lead to visual impairment and stroke.
Wroblewski says improved detection of antimicrobial resistance and antimicrobial susceptibility testing advances need to be made so that culture-based methods are no longer relied upon. “There are currently PCR methods available, but pathology needs to be better understood—such as when it is most appropriate to do a certain test,” she says.
Wroblewski would also like to see the ability to test for human papillomavirus (HPV) without needing a cervical sample. “I think Roche’s HPV test is a great step; it’s great to have an option other than the Pap smear. But there is still room to improve.” Having a PCR test available in the US to detect syphilis from a lesion would be hugely helpful. While not available in the US, some countries are already doing this.
For more information, see the related articles, “A Closer Look: STD/HIV Testing Devices” and “Diagnostics’ Role in Monitoring HIV Patient Response to Therapy.”
Karen Appold is a contributing writer for CLP. For further information, contact chief editor Steve Halasey via [email protected].