Ancient Bacteria Unearthed: 5,000-Year-Old Microbes Show Resistance to Modern Antibiotics
In a discovery that could reshape our understanding of antibiotic resistance, scientists have unearthed bacteria frozen for millennia in an underground Romanian cave, only to find they possess a remarkable resilience to contemporary antibiotics. The findings, stemming from the depths of Scărișoara Cave, one of Romania’s most significant ice caves, highlight the ancient origins of microbial defence mechanisms.
Deep within the cave, preserved beneath a 5,000-year-old ice formation, researchers identified a strain of bacteria, Psychrobacter SC65A.3. This ancient organism, isolated from a 25-metre ice core extracted from the cave’s Great Hall, has demonstrated resistance to a staggering array of modern antibiotics.
Bacteria, as a life form, have an extraordinary capacity to survive under extreme conditions. They can persist for thousands of years encased in ancient ice, locked away in permafrost, submerged in the deep sea, or dwelling in glacial lakes. These hardy microbes have evolved unique survival strategies, adapting and persisting over vast stretches of time, playing by their own evolutionary rules.
The Romanian research team, by meticulously analysing ice fragments and sequencing the genomes of various isolated bacterial strains, not only identified genes responsible for survival in frigid temperatures but also uncovered those conferring antimicrobial resistance.
A Multi-Antibiotic Adversary
The Psychrobacter SC65A.3 strain, specifically adapted to cold environments, has proven resistant to 10 modern antibiotics spanning 8 different classes. Cristina Purcarea, a scientist at the Institute of Biology Bucharest of the Romanian Academy and lead author of the study, elaborated on the significance of this finding.
“The Psychrobacter SC65A.3 bacterial strain isolated from Scărișoara Ice Cave, despite its ancient origin, shows resistance to multiple modern antibiotics and carries over 100 resistance-related genes,” Purcarea stated.
The antibiotics to which this ancient bacteria exhibits resistance are those commonly used in clinical practice for treating serious bacterial infections. These include medications employed in oral and injectable therapies for conditions such as tuberculosis, colitis, and urinary tract infections (UTIs).
Unlocking Evolutionary Secrets
While previous research has explored other Psychrobacter strains, often focusing on their biotechnological potential, the antibiotic resistance profiles of these ancient cold-adapted microbes have remained largely uncharted territory.
“Studying microbes such as Psychrobacter SC65A.3 retrieved from millennia-old cave ice deposits reveals how antibiotic resistance evolved naturally in the environment, long before modern antibiotics were ever used,” Purcarea explained. This discovery offers a crucial glimpse into the natural evolution of antimicrobial resistance, predating human intervention.
The researchers acknowledge that antimicrobial resistance is a natural phenomenon. However, they stress that its prevalence and spread have been significantly accelerated by the chronic and often widespread use of antibiotics in modern medicine. This overuse has fostered the diversification and dissemination of antibiotic resistance genes.
The findings, published in Frontiers in Microbiology, underscore the importance of understanding cold-adapted microbes, particularly in the context of rapid climate change. With approximately 20 percent of Earth’s surface comprising frozen habitats, and low temperatures characterising a significant portion of the biosphere, insights into these organisms are becoming increasingly critical.
The Growing Global Threat of Antimicrobial Resistance
Antimicrobial resistance (AMR) is a pressing global health concern, responsible for millions of deaths annually worldwide. In Europe alone, it is estimated to contribute to over 35,000 deaths each year, a figure projected to escalate in the coming years.
Several factors have converged to create a fertile ground for AMR across the continent. The European Centre for Disease Prevention and Control (ECDC) has identified key contributors, including:
- An Ageing Population: Older individuals are often more susceptible to infections.
- Cross-Border Spread: Drug-resistant pathogens are not confined by national borders.
- Overuse of Antibiotics: Inappropriate prescribing and usage by both healthcare professionals and the public.
- Gaps in Prevention and Control: Deficiencies in infection prevention and control measures within healthcare settings and the community.
Globally, the World Health Organization (WHO) reports that one in six bacterial infections is now resistant to standard treatments, a statistic that highlights the urgent need for innovative approaches and a deeper understanding of resistance mechanisms, both ancient and modern. The discovery of antibiotic-resistant bacteria frozen for 5,000 years serves as a stark reminder of the long evolutionary history of these defence mechanisms and the ongoing challenge they pose to public health.
