When Can Broad-Spectrum Antibiotics Be Avoided?

dr-brandon-webb

Dr. Brandon Webb

Brandon Webb, MD, is an infectious disease physician in the division of epidemiology and infectious diseases at Intermountain Healthcare in Utah. He has also served as an adjunct assistant professor at the University of Utah School of Medicine. Dr. Webb’s research interests include bacterial pneumonia, antimicrobial stewardship, and transplant infectious diseases.

Why did you develop the DRIP Score? Was there a particular clinical experience or patient encounter that inspired you to create this tool for clinicians?

I developed the idea for the DRIP Score while working as a hospitalist before my infectious disease fellowship. I frequently admitted patients with pneumonia who met HCAP criteria, and yet few of them ended up requiring the vancomycin and broad-spectrum gram negative antibiotics we were giving.  

When I started digging into the literature, I was surprised to find that use of these antibiotics had doubled in the last 10 years without an increase in rates of antibiotic-resistant bacteria! This led to the development of a score that would help clinicians more accurately decide which patients can safely be treated for community-acquired pneumonia.

What pearls, pitfalls and/or tips do you have for users of the DRIP Score? Do you know of cases when it has been applied, interpreted, or used inappropriately?

The DRIP Score was designed to improve specificity (less false positive identification of patients who don’t have antibiotic resistant bugs), without sacrificing sensitivity (false negatives lead to inadequate antibiotic spectrum). No score is perfect, and DRIP is no exception. We are getting ready to report results of implementation of DRIP in nearly 2,000 patients and one thing we observed is that there are some patients, particularly with chronic pulmonary diseases, who have scores <4 but are colonized with MRSA or Pseudomonas. It is sometimes difficult to determine which of these patients truly have a true lower tract infection due to drug-resistant organisms from a sputum culture alone, however. Some clinicians at our institution are using a “clinical margin for error” approach – in critically-ill patients on vasopressors or mechanical ventilation, they consider using a threshold of 3 points or higher to initiate broad spectrum antibiotics.

What recommendations do you have for doctors once they have applied the DRIP Score? Are there any adjustments or updates you would make to the score based on new data or practice changes?

I have two recommendations for clinicians using DRIP: first, it is important to know what your local microbiology rates are. While many hospitals have low rates of MRSA and Pseudomonas as causes of community-onset pneumonia, DRIP may not work as well in some institutions and in some distinct patient populations such as transplant recipients with high multidrug-resistant organism (MDRO) prevalence.  

My second recommendation is to consider de-escalating antibiotics in patients with DRIP >4 who are started on broad spectrum regimens if no resistant organism is identified and the patient has achieved clinical stability. In our hospitals, we couple the DRIP score with the MRSA nasal PCR, which has a very strong NPV and allows clinicians to deescalate vancomycin earlier if negative. The PPV is not stellar, so even if it is positive but no MRSA is found in the blood or respiratory sample, vancomycin can often still be stopped.

How do you use the DRIP Score in your own clinical practice? Can you give an example of a scenario in which you use it?

At the 21 Intermountain healthcare hospitals, calculating DRIP is part of the order sets in our ED and hospitalist/intensivist bundles.

Any other research in the pipeline that you’re particularly excited about?

DRIP has now been implemented in several places around the country and we are looking forward to publication of several centers’ experience using it, including our own.