Use of these new technologies creates opportunities for clinical laboratories and pathologists to add more value when collaborating with physicians to advance patient care

Ongoing improvements in point-of-care testing are encouraging one major academic medical center to apply this mode of testing to the diagnosis of hospital-acquired infections (HAIs). This development should be of interest to clinical laboratory professionals and pathologists, since it has the potential to create a different way to identify patients with HAIs than medical lab tests done in the central laboratory.

Massachusetts General Hospital (MGH), Harvard Medical School’s (HMS’) largest teaching hospital, has developed a prototype diagnostic system that works with doctors’ smartphones or mobile computers. The hand-held system can identify pathogens responsible for specific healthcare-acquired infections (HAIs) at the point of care within two hours, according to an MGH statement.

The researchers noted that 600,000 patients develop HAIs each year, 10% of which die, and that costs related to HAIs can reach $100 to $150 billion per year. However, as Dark Daily reported, the Centers for Medicare and Medicaid Services (CMS) does not reimburse hospitals for certain HAIs. (See Dark Daily, Consumer Reports Ranks Smaller and Non-Teaching Hospitals Highest in Infection Prevention,” October, 30, 2015.) Thus, the critical need to identify from where the infection originated, which generates a significant proportion of samples tested at the clinical laboratories of the nation’s hospitals and health systems.

Therefore, pathologists and medical laboratory scientists will understand that shifting some of that specimen volume to point-of-care testing will change the overall economics of hospital laboratories.

Smartphone-based Genetic Test for HIAs

The MGH research team created a way to do accurate genetic testing in a simple device powered by a system they call Polarization Anisotropy Diagnostics (PAD). The system measures changes in fluorescence anisotropy through a detection probe’s recognition of bacterial nucleic acid, reported Medscape Medical News. More than 35 probes for detecting bacterial species and virulence factors are available.

Optical test cubes are placed on an electronic base station that transmits data to a smartphone or computer, where results are displayed. “In a pilot clinical test, PAD accuracy was comparable to that of bacterial culture. In contrast to the culture, the PAD assay was fast (under two hours), multiplexed, and cost effective (under $2 per assay), wrote the MGH researchers in the journal Science Advances.

Assay Speed and Costs Motivate Researchers

In an article published in New Scientist, Hakho Lee, PhD, Director of the Biomedical Engineering Program at Mass General Center for Systems Biology and Associate Professor at HMS, noted that the MGH researchers wanted a diagnostic assay that was “fast, comprehensive, and cost effective.” PAD makes that possible, according to its developers. PAD enables doctors to quickly diagnosis a patient’s infection, find out whether antibiotic-resistant bacteria are evidenced in a group of patients, and detect bacterial contamination of medical devices and patient environments. All within a few hours and without the use of traditional laboratory methods.

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Hakho Lee, PhD (left), is Director of the Biomedical Engineering Program at Mass General Center for Systems Biology and Associate Professor at HMS. Ralph Weissleder, MD, PhD (right), is Director of the Center for Systems Biology at Massachusetts General Hospital. They co-authored the study on Polarization Anisotropy Diagnostics (PAD) and are members of the MSG team that created the technology. Here they are shown holding another MGH-developed device called the D3, which enables doctors to take microscopic photos of cancer cells on their smartphones. (Photo copyright: Massachusetts General Hospital.)

 

How Does PAD Work?

Francis Collins, MD, PhD, Director of the National Institutes of Health (NIH) in his NIH Director’s Blog described how PAD works:

• A sample is obtained, such as fluid from an infection;

• Genetic material from the bacteria in the sample (usually ribonucleic acid or RNA) is extracted into a small disposable plastic cartridges and amplified;

• A pair of two-centimeter plastic cubes hold the material and a “master mix”;

• The mix has DNA probes to detect genetic sequences defining bacterium, and a reporter probe attached to a fluorescent tag to generate a light signal;

• A light signal is measured when samples with copies of a target bacterial sequence are detected;

• The signal then goes to an electronic base station, which digitizes and transmits it to a smartphone equipped with a PAD app;

• The app generates a time-stamped results report.

Contamination control is part of the assay protocol as well, noted the Medscape Medical News article.

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The PAD system above is comprised of four blue and white optical testing cubes (left) stacked on top of an electronic base station (white with initials). The electronic base station transmits results to an app on a doctor’s smartphone (right), which receives the signal and displays the test results. (Photo copyright: National Institutes of Health/Park et al. Sci. Adv. 2016.)

 

Clinical Study Finds Results Faster with PAD

So how does PAD perform compared with conventional microbiology cultures?

In a pilot clinical study, the researchers tested abdominal fluid or nephrostomy samples from nine patients. They tested samples for Escherichia coli (E. coli); Klebsiella;
Acinetobacter; Pseudomonas; and Staphylococcus aureus, as well as the virulence and antibiotic resistance of each of them.

The study found that both methods obtained identical results. However, they were posted within two hours with the PAD system, as compared to three to five days necessary for bacterial culturing.

The growing emphasis on improving the diagnosis and treatment of hospital-acquired infections is why researchers are developing diagnostic systems like PAD. HAIs continue to happen, leading to a shocking 60,000 deaths each year. For labs and physicians, PAD can be an additional resource to speed diagnosis, tailor treatment to patients, and help ensure clean environments. It’s less expensive than conventional microbiology assays for the same infectious agents, and offers medical laboratories less risk of cross-contamination of specimens as compared to conventional methods.

—Donna Marie Pocius

Related Information:

Mass. General-developed Device May Provide Rapid Diagnosis of Bacterial Infections

Rapid Identification of Healthcare-Associated Infections with an Integrated Fluorescence Anisotropy System

Smartphone Device Can Quickly Diagnose Cancer

Smartphone-Based Genetic Testing Identifies Hospital Pathogens

Quick $2 Test Reveals if You Caught a Superbug in Hospital

Portable System Uses Light to Detect Bacterial Infections Faster

Consumer Reports Ranks Smaller and Non-Teaching Hospitals Highest in Infection Prevention