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MasSpec Pen Developers Looking to Move Into Microbial Identification


NEW YORK – The developers of the MasSpec Pen surgical device have demonstrated its usefulness for identifying microbes, broadening its potential applications beyond cancer.

In a study published this month in Clinical Chemistry, a team led by Livia Eberlin, associate professor of surgery at Baylor College of Medicine and inventor of the MasSpec Pen, used the device to identify bacteria in cultured samples and Gram stain types and genus directly from clinical samples.

Their findings raise the possibility that the pen could prove useful for quickly identifying bacteria during surgery for conditions like bone infection or diabetic foot infections, Eberlin said.

The MasSpec Pen consists of a handheld, disposable ionization device connected to a mass spectrometer. It works via ambient ionization, using drops of water to extract lipids and metabolites from tissue that are then analyzed via mass spectrometry to generate molecular profiles. These can be used to distinguish between different tissue types or, in the case of the recent study, different bacteria.

Last year, Eberlin and several colleagues launched a company, Genio Technologies, to commercialize the technology. Eberlin serves as the Tulsa, Oklahoma-based firm's CSO. The company has raised $1.25 million in seed funding from investors including i2E Management and the Oklahoma Seed Capital Fund.

Since initially publishing on the device in 2017, Eberlin has primarily explored its use in cancer surgery to assess tumor margins. The move into microbiology came at the request of clinicians she and her team had been working with, she said.

"We're centered in surgical applications, and one of the things we've been asked by a variety of surgeons, especially infectious disease surgeons, is [whether we] could identify bacteria when we were excising, for instance, infected bone," Eberlin said.

Identifying bacteria while a patient is still in surgery could allow doctors to more quickly move to a targeted antibiotic for their infection, she said.

The researchers started by using the pen on cultured samples to generate molecular profiles and develop classifiers. They analyzed 163 culture samples comprising 28 strains across eight bacterial species, including Staphylococcus aureus, Group A and B Streptococcus, and Kingella kingae. The effort focused on microorganisms commonly linked to pediatric osteoarticular infections, which Eberlin said her collaborators highlighted as an area where the tool could be particularly useful.

They then tested these classifiers in a validation set consisting of 74 samples spanning 15 strains. In the validation work, they found that the pen was able to distinguish between Group A and B Streptococcus with 85 percent accuracy and between S. aureus and Staphylococcus epidermidis with 97 percent accuracy. The device identified a validation set of 24 samples of Gram-negative bacteria spanning six strains with accuracy of 92 percent.

The researchers then applied their classifiers to a set of five clinical samples taken from four patients with osteoarticular infections, exploring how the device performed in direct surgical specimens without culture. They were not able to identify the bacteria down to the species level but were able to identify the Gram stain type and genus of the microbes in the different samples.

Eberlin said that she and her colleagues have since launched a larger, NIH-funded study of the approach in collaboration with pediatric infection groups at Texas Children's Hospital, Riley Hospital for Children in Indianapolis, and the University of Texas Dell Medical School.

In addition to developing classifiers to identify bacteria, the current effort also aims to identify markers of antibiotic resistance, Eberlin said.

In addition to osteoarticular infections, the researchers are exploring whether the MasSpec Pen could be useful for direct identification of bacteria in diabetic foot infections, a collaboration with the Veterans Affairs hospital at the Texas Medical Center. In these cases, direct identification could potentially help doctors more quickly decide if an infection can be treated with antibiotics or if the affected area needs to be amputated, Eberlin said, though she noted that bacterial identification is particularly challenging in these infections due to the fact that multiple microorganisms are often involved.

MALDI mass spectrometry has carved out a major role for itself in clinical microbiology, with Bruker's MALDI Biotyper and BioMérieux's Vitek MS both commonly used for microbial identification. Eberlin said that she doesn't see the MasSpec Pen as competing in that space but rather as a tool that could help clinicians more quickly make treatment decisions on surgical patients.

Current MALDI workflows require culturing of samples to obtain isolates for mass spec analysis, but identification of pathogens directly from patient samples remains a goal for many in clinical microbiology. Roughly a decade ago, Imperial College London researcher Zoltan Takats developed an ionization technology called rapid evaporative ionization mass spectrometry (REIMS) and demonstrated its ability to identify bacteria directly from human colorectal tissue. In 2014, Waters purchased the company, MediMass, that owned the REIMS technology and said that it planned to explore mass spec-based microbial identification with the system. However, since then, it has made little apparent headway in this effort.

Waters owns another ambient ionization technology — desorption electrospray ionization (DESI) — that researchers including Eberlin have used for direct analysis of tissue, but Eberlin said that it is poorly suited to analysis of tissue in a setting like a surgical suite.

"I love DESI," she said, noting that she worked on the development of the technology while a doctoral student in the lab of Purdue University researcher Graham Cooks. "It is very good for planar surfaces, if you have, say, a tissue section on a glass slide where you have very good control of the geometry."

The technology doesn't work as well with three-dimensional samples like what one typically encounters during surgery, she noted. "In the context of having, like, a raw piece of tissue, it's nearly impossible to get a reading with DESI. It's not built for that kind of specimen," she said. "That's what we built the MasSpec Pen for, so that once you have that tissue, even in vivo, you can take it as is, place a probe on its surface," and get a reading.

In addition to the microbiology work, Genio and Eberlin continue to develop the technology for use in assessing tumor margins during surgery. They are currently involved in two clinical studies at MD Anderson Cancer Center and two studies at Baylor College of Medicine. They have also placed a device at Johns Hopkins University, Eberlin said.

The system currently uses a Thermo Fisher Orbitrap Exploris 120 mass spectrometer and comes packaged as a mobile, battery-powered device that can be moved between different operating rooms.

"We've done a lot on the mobility of the system and the robustness of the system, and now we are really in a phase of validating and pushing as strongly as we can on the commercial side of things," Eberlin said.