The researchers at Massachusetts General Hospital have been working on a mechanism to detect bacterial infections in hospitalized patients. The mechanism developed at MGH first uses bacterial RNA extracted from patients, amplifies it and then performs the polymerase chain reaction process. The polymerase chain reaction is a process that amplifies a single piece of DNA, and uses it to generate a thousand to million copies of the DNA strand. This technique is used extensively in the detection and diagnosis of infectious diseases.

Currently, the healthcare techniques are painfully slow. Doctors and other healthcare officials have to wait for symptoms to appear before they can take any action. Moreover, in many circumstances, bacterial colonies need to be incubated over a long period before the bacterial cultures can be correctly identified.

The results are then stored in a plastic test tube with optical sensors attached to it. The sensors are able to identify the optical signature of specific RNA sequences that correlate to the presence of bacteria, in a process called Polarization Anisotropy Diagnostics (PAD).

The team at MGH used a prototype PAD system containing four optical cubes to test samples from nine patients and then compared the results with those extracted from conventional micro bacterial cultures. The tests were done on five samples of bacteria; Staph aureus, Acinetobacter, E coli, Pseudomonas and Klebsiella. The tests took into account the factors of resistance to antibiotics, and virulence. The results were similar in both cases.

There was a massive difference of time, however, between the two cultures. The sample produced using Polarization Anisotropy Diagnostics took less than two hours whereas the bacterial culture process took three to five days. The researchers have now designed the diagnostic probes for more than 35 different species of bacteria and virulence factors. The overall cost of running the PAD test will be no more than $2.

The test tube can then be linked with a tablet or smartphone that will display the results of the findings and will be able to perform all the steps in the diagnostic process in the near future. Dr Hakho Lee, of the MGH Center for Systems Biology (CSB), who is one of the co-authors of the study said, “This prototype still needs several improvements, including building a self-contained system housing all functions, further reducing the current assay time to less than one hour and expanding the panel of probes to even more pathogens and resistance factors.”

Dr Lee was  hopeful of the future and was quite happy with the results. He said that this system will have three very positive and revolutionary applications. He elaborated that a system that produces such quick and precise results could help diagnose patients’ infections much more quickly, help identify antibiotic-resistant bacteria in a group of patients as well as detect contaminated surroundings and objects.

What Is Polymerase Chain Reaction?

The polymerase chain reaction depends on thermal cycling, a process in which the DNA polymerase undergoes cycles of varying temperatures. The polymerase undergoes several cycles of heating and cooling for DNA melting which results in DNA cloning. Primers, which are short strands of DNA and DNA polymerase (an agent that allows DNA duplication), are essential in the procedure.

The first step involves separating two strands of DNA double helix at high temperature called DNA melting. In the second step, the temperature is lowered and the two DNA strands become the template for the polymerase to replicate. The PCR process is quite selective in nature, as the primer strand is complementary to the target DNA region.

Why Was The Procedure Developed?

According to the Centers for Disease Control and Prevention (CDC), there are 1.7 million hospital infections, also known as nosocomial infections, that directly or indirectly cause 99,000 deaths each year. These hospital infections can cause severe pneumonia, urinary tract infections and several blood infections. Many types of these hospital infections are tough to treat using standard techniques such as antibiotics. Moreover, antibiotic resistance can complicate the treatment process.

For these reasons, the researchers thought it necessary to develop a more efficient and effective method to treat hospital infections.

What Are Nosocomial Infections?

Nosocomial infections are infections that arise when the patient is admitted in the hospital, due to any unrelated diagnosis. These infections can occur up to 48 hours of hospital admission, up to three days after discharge or up to 30 days after an operation. An estimate of 9.2% of US patients acquire nosocomial infection.

Nosocomial infections are caused by pathogens in the air that can easily spread in the body. These infections can affect any patient who has been hospitalized. Patients with especially weak immune systems are at great risks of catching these diseases. These infections can also be contracted by coming into contact with other patients.

In most cases, the infections are caused due to poor environment conditions of hospitals and the hospital staff not following the sterilization process. In many cases, healthcare facilities do not follow the health and safety regulations for proper waste management, which puts the patients at a greater health risk.

Inflammation, fever and discharge are often the first signs of a nosocomial infection and patients may also face pain and skin rash at the place of infection.