Chlamydial Infections can't be prevented by just screening girls alone

Chlamydial Inclusion Bodies

Frequent testing and treatment of infection does not reduce the prevalence of chlamydia in urban teenage girls, according to a long-term study by Indiana University School of Medicine researchers published in the January 1, 2010 issue of the Journal of Infectious Diseases.
Despite the fact they were screened every three months and treated when infected, the proportion of infected girls did not change over the course of the study. On entering the study, 10.9 percent of the young women were infected. After 18 months of participation, 10.6 percent were infected; 10.4 percent were infected at the four-year mark.
Eighty-four percent of repeated infections were reinfections. In spite of being so highly motivated that they kept diaries of their sexual encounters and interacted at least quarterly with the study staff, some of the young women had unprotected sex with either an untreated partner or a new partner and subsequent infection occurred. The researchers determined that 13 percent of repeated infections were due to failure of antibiotics to cure an earlier infection; considering all infections, antibiotic treatment was 92.1 percent effective.
"The rate of infection we found in the 365 Indianapolis girls we followed is similar to the rates reported by other researchers for girls in Denver and Baltimore, so it is likely that our important new findings on reinfection can be generalized to urban teenage girls in other cities," said Byron E. Batteiger, M.D., professor of medicine at the IU School of Medicine, an infectious disease specialist who is the first author of the study.
The researchers obtained a biological sample from as many sex partners of the study participants as possible to determine if the boys were chlamydia infected. "We were able to test 22.6 percent of all the partners that the girls named in the study. We determined that 26.2 percent of the participating boys were infected -- a very high level of infection in this pool of young men to whom young women in the study were exposed," noted Dr. Batteiger.
Current national recommendations call for routine chlamydia screening of women based on age and history of sexual activity. There is no similar recommendation for screening young men.
"The high rate of reinfection we found in our study strongly suggests there may be some real limits on what we can do to control chlamydia without doing a better job of controlling chlamydia in young men," said J. Dennis Fortenberry M.D. M.S., professor of pediatrics at the IU School of Medicine, an adolescent medicine physician who is the senior author of the study.
"We also need to make sure that sexually active teens are aware of fact that unlike some other diseases, having chlamydia and being successfully treated for it does not give the individual immunity from reoccurrence," said Dr. Fortenberry, who urges physicians to repeatedly screen adolescents for the disease.
Chlamydia is the most common bacterial sexually transmitted infection and is associated with an increased risk of pelvic inflammatory disease, ectopic pregnancy, tubal infertility, and increased susceptibility to human immunodeficiency virus infection. Chlamydia is more common in sexually active teens than in any other age group.
In addition to Dr. Batteiger and Dr. Fortenberry, co-authors of the study are IU School of Medicine faculty members Wanzhu Tu, Ph.D.; Susan Ofner, M.S.; Barbara Van Der Pol, Ph.D.; Diane R. Stothard, Ph.D.; Donald P. Orr, M.D.; and Barry P. Katz, Ph.D. In addition to their IU affiliations, Dr. Tu is a Regenstrief Institute investigator, Dr. Orr and Dr. Katz are Regenstrief Institute affiliated scientists and Dr. Van Der Pol is with the Marion County Department of Health. Dr. Stothard, formerly with the IU School of Medicine, is presently affiliated with Eli Lilly and Company. The study was funded by the National Institutes of Health.
The IU School of Medicine is located on the Indiana University-Purdue University Indianapolis campus.

Sexually Transmitted Infections: Transistors Used To Detect Fungus Candida Albicans

The Nanosensors group from the Universidad Rovira i Virgili has created a biosensor, an electrical and biological device, which is able to selectively detect the Candida albicans yeast in very small quantities of only 50 cfu/ml (colony-forming units per millilitre)."The technique uses field-effect transistors (electronic devices that contain an electrode source and a draining electrode connected to a transducer) based on carbon nanotubes and with Candida albicans-specific antibodies", Raquel A. Villamizar, lead author of the study said.

The Candida samples, which can be obtained from blood, serum or vaginal secretions, are placed directly on the biosensor, where the interaction between antigens and antibodies changes the electric current of the devices. This change is recorded and makes it possible to measure the amount of yeast present in a sample.

"Thanks to the extraordinary charge transference properties of the carbon nanotubes, the fungus detection process is direct, fast, and does not require the use of any marker", remarks Villamizar, who is co-author of a study that provides details of the biosensor and was published recently in the journal Sensors and Actuators B: Chemical.

To date, conventional diagnosis of Candida has been carried out using microbial cultures, serological tests, PCR molecular biology techniques (polymerase chain reactions used to amplify DNA), or immunoassays such as ELISA (Enzyme Linked Inmunoabsorbent Assay).

These techniques require long analysis times and sometimes give rise to false positives and negatives. ELISA also requires the use of markers (compounds that must be added to detect the presence of yeast by fluorescence and other techniques).

The new carbon nanotubes biosensor, however, "makes it possible to improve some of the quality parameters of the traditional methods, for example the speed and simplicity of measurements, and it is an alternative tool that could be used in routine sample analysis", explains Villamizar.

The researcher adds that by using this biosensor "it will be possible in future to obtain a rapid diagnosis of infection with this pathogen, which will help to ensure administration of the correct prophylactic treatments".

The Candida albicans fungus exists naturally in the skin, mouth, the mucous membranes lining the digestive tract, and the respiratory and genitourinary systems. This yeast can cause anything from simple mycosis of the skin to complicated cases of candidiasis. It is much more commonly found in patients suffering from immunodeficiency, tumours, diabetes and lymphomas, among other diseases.