Isolated fluoroquinolone resistance had a larger relative impact on mortality than other phenotypic resistance patterns among a cohort of patients with Escherichia coli and Klebsiella species hospital-onset bacteremia, according to study findings.
“Infections due to gram-negative rods (GNRs) have become increasingly difficult to manage due to emerging antibiotic resistance. Previous studies have shown GNR bacteremia caused by strains resistant to extended-spectrum cephalosporins and fluoroquinolones have higher mortality than bacteremia caused by drug-susceptible strains,” Hiroyuki Suzuki, MD, from the Iowa City Veterans Affairs Health Care System and department of internal medicine at University of Iowa Carver College of Medicine, and colleagues wrote.
“Resistance to multiple classes of antibiotics limits treatment options and contributes to increased mortality. However, the contribution of individual phenotypic-resistance profiles on mortality as well as the combined effects remains unclear.”
Using national data from the Veterans Health Administration, Suzuki and colleagues analyzed the correlation between fluoroquinolone resistance (FR), extended-spectrum cephalosporin resistance (ESCR) and mortality among patients with hospital-onset GNR bacteremia.
According to the study, from 2003 to 2013, there were 6,860 patients with E. coli or Klebsiella species hospital-onset bacteremia: 4,813 with no resistance identified, 1,029 with ESCR, 202 with FR and 816 with both. Suzuki and colleagues included 19,664 patient-level matched, uninfected controls in the analysis.
Results showed that all four groups had higher 30-day mortality rates than uninfected patients, Suzuki and colleagues reported. Among the four groups, they found that the FR+/ESCR group had the highest adjusted risk ratio (aRR = 3.27; 95% CI, 2.57-4.17) and attributable fraction of mortality, followed by FR+/ESCR+ (aRR = 2.49; 95% CI, 2.18-2.84), FR/ESCR+ (aRR = 2.27; 95% CI, 2-2.57) and FR/ESCR (aRR = 2.03; 95% CI, 1.90-2.17).
“This finding may support increased antimicrobial stewardship efforts targeting fluoroquinolones and enhanced infection control protocols to prevent the transmission of these pathogens,” Suzuki and colleagues wrote.
The researchers noted several limitations of the work, including that it was a retrospective study; that they could not obtain certain clinical information, such as the source of bacteremia, details about antimicrobial therapy and length of stay and whether an infectious disease physician had consulted on the case; that most patients were male; and that “antibiotic resistances were assessed purely by phenotypic reports from clinical microbiology labs, and we did not have detailed microbiologic information, such as strain types or mechanisms of antibiotic resistance.” – by Caitlyn Stulpin
Disclosures: The authors report no relevant financial disclosures.