Hold the antianaerobics in the ICU whenever possible
FROM ATS 2024
SAN DIEGO —
“You may not be personally moved by a 2- to 5-percent absolute difference in mortality, but sepsis is so common and so lethal that even small differences in outcomes can actually translate into enormous public health implications,” said Robert P. Dickson, MD a pulmonary and critical care specialist at the University of Michigan in Ann Arbor.
If instead of prescribing piperacillin-tazobactam (Zosyn; pip-tazo) for sepsis critical care specialists were to switch to cefepime “even if you make very conservative assumptions like a modest effect size, you’re still talking about [saving] thousands of lives a year,” he said in a scientific symposium at the American Thoracic Society’s international conference.
“This is why I say this isn’t really over the horizon; this is microbiome modulation that’s happening all the time,” he said.
Most patients with sepsis in a medical ICU with respiratory, urinary or bloodstream sources of infection do not have indications for antianaerobic antibiotics, and there are no head-to-head clinical trials demonstrating a benefit for one anti-sepsis antibiotic strategy over another he said.
“In contrast, every observational study between antianaerobic and non-antianaerobic shows benefits to the anaerobe-sparing [drugs], and it’s been shown with animal models too. So to my mind, it’s already practice changing. I need to be talked into giving antianaerobic antibiotics for septic patients” he said.
Targeting gut microbiota
There are three basic approaches to focusing on the gut microbiome as a therapeutic target. The hardest is attempting to engineer an ecosystem — a fiendishly complex task with unpredictable results that has never been shown to work in either the gut or in the ICU, Dr. Dickson said.
A second approach, the use of probiotics to repopulate the gut with beneficial bacteria, is largely futile in the ICU, as the large majority of patients are on antibiotics and can’t be safely weaned off of them while in critical care. In this situation, giving probiotics would be akin to try to repopulate a forest while a forest fire is raging, he said.
The third and easiest approach is to minimize dysbiosis — imbalance of organisms in the gut — in the first place.
Anaerobic bacteria in the gut have been shown in several different disease states and animals models to be protective against pneumonia, organ failure, and death.
To see whether antianaerobic antibiotics could increase risk for adverse outcomes in the ICU, Dr. Dickson and colleagues previously conducted a retrospective study of 3032 mechanically ventilated patients in their center who received antibiotics either with or without anaerobic coverage in the first 72 hours.
They found that patients treated with early antianaerobic antibiotics had decreased ventilator-associated pneumonia-free survival (hazard ratio [HR] 1.24), infection-free survival (HR 1.22), and overall survival (HR 1.14) compared with patients who received antibiotics without anaerobic cover (all comparisons statistically significant by confidence intervals).
In a subcohort of 116 patients for whom gut microbiota data compositions were available, those who received antianaerobic antibiotics had decreased initial gut bacterial density (P = .00038), increased microbiome expansion during hospitalization (P = .011), and domination of the microbiome by Enterobacteriaceae species (P = .045). They also found that Enterobacteriaceae were enriched among respiratory pathogens in antianaerobic treated patients, and that in murine models, treatment with antianaerobic antibiotics increased susceptibility to Enterobacteriaceae pneumonia and increased the risk of death from non-infectious injuries.
