In a groundbreaking research presented at the IDWeek 2024, it was revealed that the detection of a multidrug-resistance gene was notably high amongst inpatients within a prominent New York health system, and was associated with significant fatality rates. The gene in focus, blaNDM, ranks among the top five carbapenemase genes most common in US hospitals. It is pertinent to underline the fact that carbapenemase-producing organisms (CPOs) that harbor these genes have escalated in number over time. These genes induce resistance to a variety of antibiotic classes including carbapenems, rendering infections caused by such organisms particularly challenging to treat.
The Northwell Health researchers engaged in the retrospective study launched in 2021 till the end of 2023, scrutinized blood and urine cultures from patients testing positive for a CPO. They deployed polymerase chain reaction (PCR) for blood cultures and lateral flow immunoassay for urine cultures to identify carbapenemase genes. Clinical outcomes like mortality, duration of hospital stay, and time to appropriate treatment for patients with CPOs were subsequently ascertained.
A total of 71 blood cultures and 50 urine cultures that tested positive for CPOs were evaluated. The patients were primarily between 68 to 71 years old with statically similar baseline characteristics. The CPO gene, blaNDM, was discovered in 39% of CPOs from blood and 46% from urine. Kirby An, PharmD, one of the authors, noted the alarming trend of a substantial hike in the detection of blaNDM in blood cultures in 2022, a trend that persisted through 2023. This poses significant concerns, as the NDM gene confers resistance to most of our antibiotics, including newly launched ones meant for dealing with carbapenem-resistant organisms.
The study revealed the overall mortality rate at 39% for bloodstream infections and 6% for urinary infections, with the discovery of blaNDM in blood cultures linked to a 48% mortality rate. Alarmingly, hospital stays for patients with CPO-positive blood cultures rose to 24 days in 2022 from 14.5 days in 2021, with patients whose blood infections carried blaNDM enduring hospital stays of up to 30 days.
On a positive note, mortality rate for CPO-related bloodstream infections declined to 33% in 2023, coupled with the time to appropriate antibiotic therapy dropping from around 10 hours in 2021 to around 2 hours in 2023. Rapid response to culture results, tailoring of antibiotic treatment and enhanced understanding of the resistance mechanisms are contributing factors to these positive outcomes.
Undoubtedly, there is no uniform solution for tackling CPO infections. A comprehensive understanding of the specific infection type, down to the genetic level, is crucial for maximizing patient outcomes and ensuring the judicious use of antimicrobial therapies.