The art and science of positive blood cultures

That’s been the focus of much of the lab’s energy, she says—thinking through the potential applications. “How could we make the best use of this? Is it every positive blood culture? Is it just certain blood cultures? Do you want to extend into possibly doing sterile body fluid that’s also growing in the blood culture media?”

All such questions were part of what Dr. Morgan calls the fascination, fun, and intrigue of using the Arc.

Naturally, other questions came into play as well. Could the lab perform its testing at lower cost? Using the Arc-MALDI combination, could it replace the front-line use of multiplex molecular panels?

Gazing beyond the usual questions, however, might enable laboratories to spring some fresh ideas, Dr. Morgan suggests. Like one’s taste in art, it will vary from user to user. “I think it’s going to be up to each individual laboratory to see how they can best use it,” Dr. Morgan says. “And in their particular hospital setting, how they can create an algorithm to make it most useful. I think that’s one of the nice things about the Arc—you can use it in variable ways.”

When she and her colleagues began using it in their own lab, she recalls, “we were thinking narrow-range thoughts.” That included testing organisms that didn’t identify on another Accelerate system—the Pheno—the lab was using, as well as organisms that weren’t identified with molecular panels.

“Then we thought: Well, why do that? Do we need to use that molecular system at all? Let’s just go directly to Arc.” In other words, they decided to turn it around. Rather than do molecular panels upfront, these panels became the reflex option for organisms such as Staphylococcus and Enterococcus for which detection of resistance genes could help optimize patient therapy.

Dr. Dien Bard, too, is a fan of innovative thinking, noting that MALDI has shaken things up in laboratories for the better. “It’s really changed the way we have worked up organisms and identified organisms for patient care. Broadening how we use that system is important.” That could include not only implementing it for other organisms, such as molds and mycobacteria, but also looking at other types of specimens in addition to blood. “Thinking outside the box,” she says.

She notes that interest is growing in using MALDI for resistance and susceptibility testing. “We’re not there yet, to the point where we can use it on a routine basis. But it would be exciting and great to use if it were simplified enough so that labs could use it that way.”

Dr. Morgan considers her laboratory to be in the early stages of using the Arc-MALDI combination. “I’m not sure we’ve even reached our full potential yet.” She and colleagues continue to accumulate data and present it to their stewardship group.

Further down the road, she expects to see the field accelerate—move toward more systems for rapid susceptibility testing. “Now we can offer Arc with MALDI for rapid IDs for positive blood cultures and work toward incorporating this information into rapid susceptibility systems when they are available.”

That’s one leg of the three-legged stool that underpins most decisions in the lab, says Dr. Dien Bard. “You want something that’s going to be better than your existing system. Is it going to be faster? Is the performance of the test going to be improved? Will it be lower cost? Those are typically the three rules we tend to look at when making a decision about new tests—better, faster, or cheaper—or and cheaper. If you can get all three, that’s great.”

(Although faster isn’t always better. If the result isn’t immediately actionable, it may not justify the need to speed things up further. “That could help determine what kind of approach you want to pursue,” Dr. Dien Bard says.)

Dr. Morgan also sees costs driving how laboratories maneuver. “Quality is always your first thought in any endeavor,” she says, “but let’s be honest that cost isn’t far behind.” If the lab could use a method such as Arc with MALDI to replace a more expensive system, with similar turnaround times, or to identify truly unusual organisms that can’t be identified with a molecular panel, “it could be a very nice addition, long term, to our laboratory,” Dr. Morgan says, noting that her experience to date has been promising.

“It’s not 100 percent—it’s not going to solve all your problems,” she says. “But I think it’s going to be at least the start of some great things.”

For that to happen, imagination needs to be the fastest out of the starting blocks. “A lot of labs have gotten stale,” Dr. Morgan observes, “just sending everything to a very expensive molecular panel.” Not that she’s pointing fingers. “We have been on that road a little bit ourselves.” So when a new option comes along, such as Arc plus MALDI, with its interesting possibilities, she says, “Keep an open mind and continue to be creative.”

Thinking big can be hard, particularly for labs that are busy and short of staff. “And we’re all worn out from COVID,” she says. “Let’s just face it—it’s been a horrible couple of years.” All of which have stifled creativity.

She suggests starting with a basic question: What can we do with this system? The flexibility and ease of use make it worth considering for labs looking to improve turnaround times on their blood culture bench or for sterile body fluids, she says. “It could provide some alternatives to costly molecular amplification systems.”

Not that everyone will appreciate the creativity itself, Dr. Morgan concedes. Cedars-Sinai’s infection control and stewardship group appreciates that the microbiology lab is continually looking to improve technologies. But not all physicians will understand the advancements, though they are appreciative of the rapid organism identification from positive blood cultures, she says. Her business manager and administration will definitely take note of lower costs.

The effort has been worth it. Dr. Morgan has found that developing ways to use Arc plus MALDI for positive blood culture organism identification provided much-needed respite from the daily grind. “It was fun to think about something a little creative that could also benefit our patients.”

Karen Titus is CAP TODAY contributing editor and co-managing editor.