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HAIs caused by gram-negative bacteria, MRSA increase mortality risk
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Data from more than 100 hospitals affiliated with the U. S. Department of Veterans Affairs showed that health care-associated infections due to gram-negative bacteria and MRSA were associated with significantly higher 30- and 90-day mortality risks.
The study is the largest of its kind to estimate mortality risks associated with HAIs caused by multidrug-resistant gram-negative bacteria, according to Richard E. Nelson, PhD, of VA Salt Lake City Health System and department of internal medicine at the University of Utah School of Medicine, and colleagues.
“Several existing studies have identified an increased risk of mortality associated with nosocomial infections due to gram-negative bacteria, including a high crude mortality rate for Acinetobacter baumannii ranging from 15% to 55%,” the researchers wrote. “However, these studies have been limited to patients from just one or two hospitals.”
During the study, Nelson and colleagues identified 218 MDR Acinetobacter cultures, 1,026 MDR Pseudomonas aeruginosa cultures, 3,498 MDR Enterobacteriaceae cultures, and 3,471 MRSA cultures from October 2007 to November 2010. Patients with MDR gram-negative bacteria were propensity-score matched to 14,591 participants without positive cultures. Those with MRSA were matched to 12,499 participants.
Compared with the propensity-matched cohort, the 30-day mortality rate was significantly higher among patients with MDR gram-negative bacteria, including those with invasive cultures (RR = 2.32; 95% CI, 1.85-2.92), which are likely true infections, as well as noninvasive cultures (RR = 1.33; 95% CI, 1.22-1.44), which likely represent colonization. Similarly, patients with HAIs caused by MRSA also had an increased risk for 30-day mortality, including those with invasive (RR = 2.77; 95% CI, 2.39-3.21) and noninvasive cultures (RR = 1.32; 95% CI, 1.22-1.5). The researchers observed similar results when assessing for 90-day mortality.
The estimated 30-day mortality rate was 4.9% among patients with a MDR gram-negative infection and 5.9% among patients with MRSA. The 90-day mortality rate was slightly higher at 8.5% among patients with a MDR gram-negative infection and 7.4% among patients with MRSA. The highest risk for mortality was among patients with MDR Acinetobacter (RR = 3.34; 95% CI, 1.97-5.66).
“These results are important because they underscore the mortality burden attributable to antimicrobial-resistant infections and because they provide a baseline that can be used to assess the impact of improvements in infection control, such as methods to improve handy hygiene adherence, improved surveillance and patient isolation techniques, or antimicrobial stewardship programs,” Nelson and colleagues concluded. “Evaluations of the effectiveness of these interventions should include economic evaluations of both the costs of the resources required to undertake the interventions and the benefits of prevented mortality and morbidity.” – by Stephanie Viguers
Disclosure: The researchers report no relevant financial disclosures.
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