EIRMC launches next generation of bacterial identification

The Eastern Idaho Regional Medical Center’s Microbiology department now offers MALDI-TOF, the next generation of bacterial identification.

This new technology reduces the turnaround of bacterial testing by an average of 1.5 days which ensures patients are diagnosed and treated with the right antibiotics faster.

Traditionally, the process to identify the type of bacteria took 12 to 48 hours, and sometimes up to 72 hours, but with the MALDI-TOF Technology, bacterial identification is reduced to 20 seconds.

According to EIRMC officials, this technology also reduces the chance of a patient developing antibiotic resistant infections.

Here’s how this works.

Every bacteria has a unique protein “fingerprint.” If doctors can determine the fingerprint of a bacterium, they know its identity. The MALDI-TOF is a mass spectrometer that measures the size and charge of the bacterial “fingerprint” in order to identify the specific bacteria type.

Step 1- Plating and Growing the Bacteria: Specimens from a suspected infected site are sent by a physician to EIRMC’s microbiology department. The microbiologist’s job is to grow bacteria from the specimen to identify its type. Specimens are plated onto specialized agar plates, each containing different nutrients to support growth of different types of bacteria. The plates are incubated for 18-24 hours.

Step 2- Identifying the Bacteria: Once colonies have grown, the microbiologist places the unidentified bacteria on a metal plate with targets etched into it. Once dried, a solution containing crystallized molecules (called “matrix”) is added to the bacteria on the targets. As the matrix dries, it binds specifically to the proteins in the bacteria.

The plate is then placed in the loading platform of the MALDI-TOF, and a laser is lined up on the targets. When the laser hits the target, the resulting energy breaks apart the bacteria and releases its protein. The laser’s energy also causes the matrix, which is bound to the protein, to transfer a positive charge to the protein. The positive charge allows the protein to “fly” to the top of the vacuum chamber.

The “time of flight” for the set of proteins to travel to the top of the vacuum chamber is measured. This measurement tells the microbiologist which proteins are present in the bacteria. With this unique protein “fingerprint,” a positive ID of the bacterial type can be made.

This step, identifying the bacteria, previously could take up to 72 hours. With the new MALDI-TOF technology, this is all completed in about 20 seconds.

Step 3- Testing to Fight the Bacteria: Now, we confirm which antibiotics are best to kill the patient’s infection. The bacteria is placed in wells, which contain various antibiotics at different concentrations. The Microbiologist reviews the wells after 18 hours; based on bacterial growth- or lack of- we can determine if the bacteria is sensitive to an antibiotic (a good thing) or resistant to it (not a good thing).