CAP TODAY Pathology/Laboratory Medicine/Laboratory Management
Kevin B. O’Reilly
March 2016—For laboratories performing virology testing, taking advantage of molecular testing’s superiority to traditional testing methods is a no-brainer. But leaders in the University of Michigan’s clinical microbiology laboratory have found that the push to go all molecular for virology testing must be tempered by attentiveness to clinician preferences and a collaborative approach that’s likelier to make the journey a success.
So says Duane Newton, PhD, clinical microbiology director at the University of Michigan Health System in Ann Arbor. Compared with a high of nearly 6,000 viral cultures performed in-house during the 2009–2010 fiscal year, the Michigan clinical microbiology laboratory performed fewer than 1,000 viral cultures during 2014–2015, and that figure appears to be dropping to “essentially zero” in this fiscal year.
It is unclear how many laboratories performing virology testing have gone this far in their transition to molecular, Dr. Newton tells CAP TODAY.
“We’re at least in the middle part of a journey where it’s becoming more commonplace,” he says. “What is clear is there’s some contention and debate about approaches, and differences of opinion about how to approach this [move to molecular].… There’s lots of communication that has to happen within your institution. What might be right for mine might not be right for your institution.”
At Michigan, one of the few examples in which molecular is not the go-to method is for nonblood specimens tested for cytomegalovirus. In retrospect, Dr. Newton said during a session at the Association for Molecular Pathology’s annual meeting last November, this was a case where he and his laboratory colleagues moved too far too fast.
“One of the mistakes that we made was assuming too much,” said Dr. Newton, who is also associate director of the Division of Clinical Pathology and an associate professor of pathology at Michigan. “In our quest to eliminate cultures, CMV culturing was one of our targets. We started evaluating quality assays for testing of nonblood specimens, primarily respiratory tract specimens. We went through the process of validating specimen types and demonstrating that we could consistently and accurately detect CMV with those specimens and as a result felt comfortable discontinuing CMV cultures.
“That’s when we decided to talk to clinicians and say, ‘This is what we’re going to do,’” Dr. Newton added. “And our infectious disease doctors and lung transplant pulmonologists said, ‘Wait a minute. PCR is going to be way too sensitive. We already over respond to the positive cultures. And now you’re going to give us 30 to 50 percent positives, and people are going to over respond to this as well.’”
Duane Newton, PhD
In response, Dr. Newton and his laboratory colleagues decided to cancel plans to perform CMV testing by PCR and developed a process to send out any requests for culture so they could eliminate the culturing in-house. Nonetheless, it was a lesson learned.
“It’s one of those things where we should have talked about this before we went down this road,” he said. “It reinforces to us that need to engage the users as early in the process as possible.”
Another example, more recently, where Dr. Newton has opted to defer to clinicians is in neonatal herpes simplex virus testing. Some pediatricians and infectious disease physicians at his institution objected to using PCR for HSV in neonatal patients, noting that the American Academy of Pediatrics’ Red Book embraces culturing as the gold standard method in these cases.
These clinicians “were not supportive of using molecular in this scenario because they felt it was too sensitive and would pick up colonization that you can have exposure to during birth. They felt that it was not necessarily infection—that it’s superficial contamination and that culturing would be definitive because it’s more specific for infection,” Dr. Newton tells CAP TODAY.
How is neonatal HSV testing handled now?
“We send it out for culture,” Dr. Newton says, noting there is about one request a month for HSV culturing. “The volume is too low to have it in-house but it’s available on request, when that clinical situation arises, and that’s something communicated by the clinical teams [to] the lab so that we can facilitate that. And that was one of the parts of the decision. Since we weren’t going to perform conventional methods anymore, including culturing, we needed to figure out how our level of service needed to change to accommodate that.”
Pathology residents help manage all viral culture test requests by consulting a protocol for when send-out of such test requests is warranted, Dr. Newton said at the AMP meeting.
The pathology residents will “look at the order, look at the patient’s chart, and communicate with the physician as necessary,” he said. “We want to see that this is a clinical situation that actually requires it, or is the clinician just checking boxes and doesn’t realize we have better tests in-house. Most requests are actually eliminated through that process. The ones where there really is a justification, the clinicians are aware of that and now are giving us a heads-up, saying we have this patient and need to have a culture for X, Y, and Z. So it’s a pretty streamlined process.”
Acquiescing to clinician concerns about molecular tests being too sensitive is a practice that not everyone endorses.
During the question-and-answer portion of Dr. Newton’s AMP talk, Paul Schreckenberger, PhD, rose from the audience to speak.