Trends in Carbapenemase-Producing Organisms: Prevalence, Treatment, and Outcomes
A study of carbapenemase-producing organisms found similar rates of infections, highlighting treatment challenges, the role of rapid diagnostics, and surveillance on antimicrobial stewardship due to high mortality rates.
Infections caused by carbapenemase-producing organisms (CPOs) are a growing threat to patient health, especially in healthcare settings. A recent study presented by Kirby An, PharmD, PGY2 infectious disease pharmacy resident at IDWeek, examined trends in CPO prevalence, treatment challenges, and patient outcomes. The study emphasizes the morbidity and mortality linked to these infections, underlining the importance of rapid diagnosis and antimicrobial stewardship.
According to An, “One of the major findings in our study was that our New Delhi Metallo-beta-lactamase (NDM ) and Klebsiella pneumoniae Carbapenemase (KPC) cases were very similar. Nationally, the CDC has defined KPC as the most prevalent carbapenemase gene. But here, we’re seeing NDM and KPC cases almost at the same level.” This underscores the importance of understanding local resistance patterns in shaping effective treatment strategies and guiding antimicrobial stewardship efforts.
CPOs, driven by carbapenemase genes such as blaKPC, blaOXA-48-like, blaNDM, blaVIM, and blaIMP, are becoming more common, with Klebsiella pneumoniae emerging as the dominant strain in blood and urine cultures. The study found that patients with NDM-positive CPO bacteremia had mortality rates of 42% in 2022 and 33% in 2023, while those with NDM-positive urine infections had a mortality rate of 6%.
“When we looked at our trends and outcomes, we saw that in 2023, the median time for initiating appropriate therapy was reduced to as little as about two hours. We know that getting patients onto appropriate therapy, especially for blood cultures, is critical. Unfortunately, however, mortality rates remain quite high,” An said.
The study also observed progress in rapid diagnostics and timely antimicrobial therapy. The introduction of Polymerase Chain Reaction (PCR) testing for blood cultures and phenotypic carbapenemase production tests (such as the CarboFive assay) for urine specimens decreased the median time to appropriate antimicrobial therapy to 2 hours for blood infections in 2023, down from 3.9 hours in prior years. Despite these improvements, patients with blood infections had an average hospital stay of 20 days and a 39% mortality rate, while those with urine infections had 13-day hospital stays, a 6% mortality rate, and a 50% readmission rate.
Despite high mortality, An explained, “One of the things we're really fortunate to have in our health system is the ability to use these different technologies and methods to identify carbapenemase genes. Once identified, we relay that information to our infectious disease teams and our tele-antimicrobial stewardship team. The tele-ASP team consists of infectious disease pharmacists who work during off-hours or overnight shifts. They can quickly respond to cultures and sensitivities as they come back, allowing for faster adjustments to antimicrobial therapy to cover these specific infections.”
This demographic trend, particularly among older adults with underlying health conditions, highlights the population most affected by these infections and the challenges in managing their care. A retrospective review of 71 blood cultures and 50 urine cultures (121 CPO-positive samples) from 10 hospitals, collected between January 2021 and December 2023, identified the blaNDM gene in 39% of blood isolates and 46% of urine isolates. “We also had patients with various comorbidities, such as diabetes, cardiovascular disease, and some with malignancies,” An explained.
This study highlights the threat of CPOs in healthcare settings, particularly those harboring the blaNDM gene, which is linked to higher mortality rates. Despite advances in diagnostic technology and faster time to therapy, the study underscores the need for ongoing surveillance, rapid diagnostic methods, and effective antimicrobial stewardship programs to reduce the risks posed by these resistant organisms.
