Published in the June 2016 issue of Today’s Hospitalist
THINK YOU KNOW how to diagnose and treat Staph aureus bacteremia (SAB) to ensure the best possible outcome? A new study out of the University of Miami’s Jackson Memorial Hospital suggests otherwise. In that study, researchers found that care processes were short-changed and inconsistent—and that faulty SAB management contributed to a high clinical failure rate of 32.8%. That was the case even though an antimicrobial stewardship program was in place and ID consults were available.
Published in the January issue of the Journal of Hospital Medicine, the retrospective looked at 250 SAB cases involving 241 patients and closely examined the care processes that might affect outcomes. Those included antibiotic choice and timing of initiating antibiotics, as well as the timing of follow-up blood cultures, the use and timing of ID consults, and echocardiogram orders.
The authors also looked at whether a presumed infection source was documented and if foreign bodies—devices, prostheses, catheters—were identified. Just about half the patients in the study were identified with MRSA (51.4%) and half MSSA (48.5%). Clinical failure was defined as in-hospital mortality or persistent bacteremia.
“Some people still don’t choose the right first-line therapy.”
The researchers found that departures from SAB treatment standards occurred across patients’ hospital stays. Patients with clinical failure had relatively longer elapsed time between their initial positive and follow-up blood cultures: four days on average. Only 40% of the patients with clinical failure received an ID consult. The consults that were called occurred on average a week after initial diagnosis, but up to 13 days later in some cases.
Further, physicians didn’t identify (or document) an infection source in 30% of patients, and only 45% of those with clinical failure received an echocardiogram. And in many cases, first-line therapy choice, dosing and duration were either suboptimal or flat-out inappropriate.
Today’s Hospitalist discussed those findings with two of the authors, ID specialists Lilian Abbo, MD, and Rossana Rosa, MD.
What surprised you most about your results?
Dr. Abbo: We found many more opportunities to improve the management of SAB than we expected, particularly in the area of follow-up. Numerous studies have shown that timely follow-up of blood cultures improves SAB outcomes. But in our study, only 19.2% of patients with clinical failure had a repeat culture within two days, and only 20.5% had one within four days.
Vancomycin-level monitoring was also inadequate or inconsistent, and rates of early consults with ID specialists were low. The source of infection wasn’t identified in 30% of the MRSA patients and 44% of MSSA patients, suggesting that the history and physical weren’t thorough enough or the workup didn’t go far enough. If you don’t know the source, you might not treat the infection appropriately.
It was also surprising that some people still don’t choose the right first-line therapy. With MSSA, the drug of choice is a beta-lactam unless there’s a true allergy. But we still saw many doctors choosing vancomycin, even though we know you get better outcomes with beta-lactams. We also saw physicians choosing the wrong second-line therapies or the wrong vancomycin dosing.
Your hospital’s SAB management performance was similar to what studies have found in others. Why do these issues persist?
Dr. Rosa: We know from the evidence that when you have an SAB management protocol in place and an ID consult done, you tend to do things right. Some organizations are moving toward SAB bundles and mandatory ID consults, but there’s always resistance to “mandatory.” Part of the issue too is that ID specialists are sometimes undervalued.
The benefit of an ID consult in managing SAB is well-documented, with consistent results favoring it. In our study, we found that early consultation—within the first six days of bacteremia onset—reduced the risk of clinical failure. The decisions you make in those first 48 to 72 hours will affect the rest of the clinical course, whether by identifying and addressing the source of infection or, for longer-term planning, determining treatment duration.
You wouldn’t prescribe chemotherapy if you weren’t an oncologist, but anyone can prescribe antibiotics regardless of their specialty or years of training. That’s a problem with something as complex as managing SAB, and it’s one reason we have issues with super-bugs and hospital infections.
On the positive side, physicians in private community hospitals consult ID specialists on SAB cases more frequently and more quickly than those in academic centers.
Your hospital instituted a “Staph aureus powerplan,” in part in response to your findings. How does that work, and has it made a difference?
Dr. Rosa: The intervention is a two-step process in which our antimicrobial stewardship program is alerted when a blood culture turns positive with SAB. The program then contacts the doctor treating the patient and suggests using the “Staph aureus powerplan.”
It’s an order set with the basic initial orders that are usually done for SAB cases, but it also suggests an ID consult. And for vancomycin, our pharmacy now provides a “vanco dosing” service, and the powerplan includes an order for that service.
We are in the process of analyzing the post-intervention data. But we have definitely seen a 30% increase in ID consults, and hospitalists have been particularly receptive.
How should hospitalists approach SAB management, depending on the resources available?
Dr. Abbo: They should start with a very good history and physical and absolutely identify the source of infection so they can choose the right drug, dose and therapy duration. If a patient comes in off the street without dialysis, a catheter, a central line or a prosthesis, hospitalists have to get a better history and figure out where the infection is coming from, which means determining which ancillary studies they need.
That sounds straightforward. But our study and others have found that care processes often aren’t structured enough and that some physicians don’t get the right guidance. The Infectious Diseases Society of America has good guidelines on managing SAB, but do people actually read them? Most physicians have handheld devices now, so there’s no reason not to look those up.
If patients need an ID consult, physicians should get one early on, not a week later. In fact, as soon as doctors know it’s staph, they should get an ID consult because that tends to improve the processes of care. Hospitalists are at the forefront of treating hospitalized patients, and most of them do a great job. But an early ID consult can help improve outcomes and decrease length of stay.
Another area hospitalists should focus on is the interval for repeat cultures. If the culture is positive, repeat it the next day to make sure the bacteria weren’t transient, and then start antibiotics. Then repeat the culture at 48 hours.
Of course, if the patient is very sick, you’ll have to start antibiotics right away. But the point is that starting antibiotics early might mask culture results.
Bonnie Darves is a freelance health care writer based in Seattle.