Certain laboratory technique allows rapid detection of eye pathogens

May 10, 2010

A laboratory technique using real-time polymerase chain reaction (PCR) that copies DNA segments may allow clinicians to accurately identify pathogens infecting the cornea more quickly than standard methods, according to a report in the May issue of Archives of Ophthalmology.

"Corneal ulcer, including bacterial keratitis, fungal keratitis and Acanthamoeba keratitis, can cause corneal opacity, deteriorated or even lead to some lifelong complications," the authors write as background information in the article. "Bacterial culture and smear examination using corneal scrapings is the conventional method to detect causative pathogens of corneal ulcer. However, bacterial culture is time-consuming and results of smear examination depend on the laboratory technician's skill. Therefore, a fast and accurate diagnostic method is highly desirable."

In recent years, PCR has become more widely used clinically for the detection of bacteria and viruses; it amplifies a small segment of DNA for assessment. Motoki Itahashi, M.D., Ph.D., and colleagues at Kinki University School of Medicine, Osaka-Sayama, Japan, compared real-time PCR using corneal scrapings to bacterial culture for the detection of six common bacteria and fungi in 40 eyes of 40 patients diagnosed with corneal ulcer.

The real-time PCR assay delivered results within two hours, whereas culture results were examined after 48 hours. Of the 40 eyes, 20 had the same pathogens detected by both methods and six showed negative results by both methods. Results differed in 14 eyes: 11 eyes had positive results for one of the six pathogens only on PCR, two had positive results on culture only and one eye had positive results for two different pathogens.

"Although PCR has a high risk of false positivity, we actually treated the patients with positive PCR results only according to their real-time PCR results and the treatment outcomes were all satisfactory," the authors write. "This may demonstrate a better detection sensitivity in the PCR assay."

"In conclusion, though the numbers included in this study were limited, particularly with fungal ulcers, we have demonstrated that real-time PCR can accurately and simultaneously detect bacterial and fungal in a speedy fashion," the authors write. "With real-time PCR, it may be possible to develop a diagnostic kit for pathogen-specific detection in the busy ophthalmic clinical practice."

More information: Arch Ophthalmol. 2010;128[5]:535-540.

Related Stories

Recommended for you

Decrease in sunshine, increase in Rickets

November 17, 2017
A University of Toronto student and professor have teamed up to discover that Britain's increasing cloudiness during the summer could be an important reason for the mysterious increase in Rickets among British children over ...

Anti-malaria drug shows promise as Zika virus treatment

November 17, 2017
A new collaborative study led by researchers at Sanford Burnham Prebys Medical Discovery Institute (SBP) and UC San Diego School of Medicine has found that a medication used to prevent and treat malaria may also be effective ...

Scientists identify biomarkers that indicate likelihood of survival in infected patients

November 17, 2017
Scientists have identified a set of biomarkers that indicate which patients infected with the Ebola virus are most at risk of dying from the disease.

Research team unlocks secrets of Ebola

November 16, 2017
In a comprehensive and complex molecular study of blood samples from Ebola patients in Sierra Leone, published today (Nov. 16, 2017) in Cell Host and Microbe, a scientific team led by the University of Wisconsin-Madison has ...

Study raises possibility of naturally acquired immunity against Zika virus

November 16, 2017
Birth defects in babies born infected with Zika virus remain a major health concern. Now, scientists suggest the possibility that some women in high-risk Zika regions may already be protected and not know it.

A structural clue to attacking malaria's 'Achilles heel'

November 16, 2017
Researchers from The Scripps Research Institute (TSRI) and PATH's Malaria Vaccine Initiative (MVI) have shed light on how the human immune system recognizes the malaria parasite though investigation of antibodies generated ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.