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A new study has raised alarm over a highly resistant strain of bacteria that could pose a significant global public health threat, particularly in Asia. Researchers have identified a virulent new variant of Acinetobacter baumannii, a bacterium resistant to carbapenem antibiotics, which has been spreading widely across hospitals in the region.
The study, published in Nature Communications, highlights the emergence of the ST164 strain of Carbapenem-resistant Acinetobacter baumannii (CRAB) in a Chinese intensive care unit (ICU). The research, conducted over three months in 2021, reveals the alarming presence of CRAB bacteria, with ST164 accounting for 40.2% of samples collected from ICU patients in Hangzhou, China. This new strain is notably more resistant to carbapenems, a class of antibiotics considered last-resort treatments for infections caused by multi-drug resistant organisms.
Led by researchers from the University of Birmingham and Zhejiang University, the study focused on how infection prevention and control (IPC) measures impacted the spread of CRAB within hospital settings. The researchers found that a staggering 80.9% of A. baumannii isolates in ICU patients were CRAB, with ST164 emerging as a dominant strain. Other hospital wards and transferred patients were identified as potential sources of new strains entering the ICU.
The emergence of ST164 is particularly concerning because of its high levels of resistance compared to previous dominant strains. The study notes that the ST164 strain has developed twice the resistance to carbapenems as the previously prevalent GC2 strain, which fell from 99.5% of CRAB isolates in 2019 to just 50.8% by 2021. This suggests that ST164 is gradually establishing itself as a major threat, particularly in ICU environments where vulnerable patients are at high risk of infection.
“CRAB poses a serious risk to hospitalized patients, causing severe diseases such as pneumonia, urinary tract infections, bacteremia, meningitis, and soft tissue infections,” said Professor Alan McNally, co-author of the study from the University of Birmingham. “While ST164 caused fewer infections than the GC2 strain during our study period, its high antibiotic resistance levels make it crucial to monitor its spread closely.”
The bacteria can survive for extended periods on hospital surfaces and medical equipment, contributing to the difficulty of controlling outbreaks. Infected patients can become colonized with CRAB within just 48 hours of admission, with hospital staff, shared equipment, and hospital infrastructure playing key roles in its transmission.
The study underscores the urgent need for ongoing IPC measures in hospitals to contain the spread of CRAB. With limited treatment options available, the World Health Organization has classified A. baumannii as a priority pathogen requiring novel therapeutic solutions.
“The health implications of CRAB, especially the ST164 clone, are profound, affecting patient outcomes and straining healthcare systems globally,” said Professor Willem van Schaik, another co-author of the study. “In the absence of new therapeutic agents, effective IPC strategies are crucial to preventing widespread morbidity and mortality caused by these drug-resistant bacteria.”
The research highlights the critical role of genomic surveillance in tracking the evolution of antibiotic-resistant strains. By using high-resolution whole-genome sequencing, the study provides valuable insights into how CRAB spreads and evolves in hospital environments, offering a roadmap for future containment strategies.
As antibiotic-resistant infections continue to rise, this study serves as a stark reminder of the pressing need for continued vigilance, innovation in treatments, and global cooperation to combat the growing threat of resistant pathogens.
Source: Liu, H., et al. (2024). Longitudinal genomics reveals carbapenem-resistant Acinetobacter baumannii population changes with emergence of highly resistant ST164 clone. Nature Communications. DOI: 10.1038/s41467-024-53817-x
