December 02, 2013
1 min read

DNA test discerned bacteria responsible for trachoma

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A commercial DNA microarray assay successfully identified different species of Chlamydiaceae responsible for trachoma in Nepalese patients, according to study results recently published in Emerging Infectious Diseases.

Trachoma is the leading cause of preventable blindness, and rates of the infection have increased in the past few decades, according to background information in the study. In response, WHO developed a program to eliminate blinding trachoma by 2020.

"Although some Chlamydiaceae screening tests and strain-typing methods exist, they are expensive, are time-consuming, require trained personnel, and are available only in specialized laboratories; most do not discriminate among species of Chlamydiaceae," the researchers wrote.

Deborah Dean, MD, MPH, a senior scientist at Children's Hospital Oakland Research Institute, and colleagues investigated whether use of the ArrayTube assay (Alere Technologies) could discriminate Chlamydiaceae species in DNA extracted from conjunctival samples of 101 patients with trachoma from a trachoma-endemic region in Nepal, aged 1 to 65 years. RNA samples were subjected to real-time PCR for comparison.

The researchers found that 70.3% of the patients were infected. Compared with real-time PCR, ArrayTube sensitivity was 91.7% and specificity was 100%. All of the genotypes from positive samples identified by the ArrayTube were matched with those identified by the real-time PCR.

Seventy-six percent of the species identified included single infections with Chlamydia trachomatis, C. psittaci, C. suis or C. pecorum, and 24% were mixed infections that included C. pneumonia. Ocular infections resulted from five Chlamydiaceae species.

"Identifying Chlamydiaceae species distribution among persons in a trachoma-endemic area is critical for understanding disease prevalence and instituting appropriate therapeutic regimens for the specific species," the researchers concluded. "For assessment of the prevalence of infections caused by all Chlamydiaceae species and for a better understanding of their zoonotic origins, additional studies using the ArrayTube are warranted in other trachoma-endemic countries worldwide."

Disclosure: The researchers report no relevant financial disclosures.