Scientists in Germany tested urine samples from hospitalized patients and were able to effectively separate and accurately identify bacteria using Matrix-Assisted Laser Desorption Ionization-Time of Flight (MALDI-TOF) mass spectrometry.

The MALDI-TOF technique identifies bacteria by analyzing their proteins directly from the urine sample. MALDI-TOF mass spectrometry works by firing pulses of UV light at biological samples. All the particles become charged and are then forced down a tunnel by an electrical force.

The speed of the particles depends on their mass; thus, biomolecules such as proteins or DNA can be identified. As bacteria do not need to be cultured on agar, the MALDI-TOF method reduces the time to identify UTI-causing bacteria to less than 30 minutes. In addition, MALDI-TOF can detect and identify bacteria at much lower levels than are needed for current standard diagnostic techniques.

The study was performed by scientists at the University Hospital Essen in Germany. Dr. Frank Mosel, who led the study, believes the MALDI-TOF method will have huge benefits for patients who suffer from UTIs. Dr. Mosel said, "Identifying bacteria quickly and accurately using MALDI-TOF means treatment for UTIs can be started at an early stage and with an antibiotic targeted at the correct bacterial culprit."

The MALDI-TOF technique is unaffected by any antibiotics the patient may have taken and the bacteria sample does not need to be cultured before testing. The sensitivity of the test is nearly 100 times higher than the minimum clinical threshold for UTI diagnosis.

Dr. Mosel believes that the use of MALDI-TOF mass spectrometry could be extended more widely as a medical analysis tool. "This method could quite feasibly be extended to blood, cerebrospinal fluid, and other bodily fluids to detect bacteria or even fungi," he said.

However, there are certain limitations to the MALDI-TOF methods for identifying bacteria. For example, bacteria in urine samples from patients who had undergone surgery for lower urinary tract (e.g., bladder) cancers could not be detected because human proteins produced interfered with the urine analysis.

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University Hospital Essen