Emergence of biocide resistance gene-bearing, colistin and carbapenem-resistant hypervirulent Klebsiella pneumoniae in a Teaching Hospital in China after the COVID-19 pandemic

Background: During the coronavirus disease 2019 (COVID-19) pandemic, excessive antimicrobial agents and chemical biocides were used to manage secondary bacterial infections and halt the virus spread, which might lead to increased antibiotic and biocide resistance within healthcare settings. Methods: This study aimed to characterize the carbapenem-resistant Klebsiella pneumoniae (CRKP) clinical isolates identified in an Emergency Room of a teaching hospital in northwest China post-COVID-19 pandemic (January 2023 to July 2024), with a total of 23 isolates retrospectively included and analyzed. Antimicrobial and biocide susceptibility testing were performed using broth dilution method to investigate the antibacterial activity of the 17 antibiotics and 5 biocides against, with resistance-related genes (carbapenemase, mobilized colistin resistance (mcr), and efflux pump genes) detected by PCR. The hypervirulent phenotype was analyzed by string test, PCR, and mouse experiments. Results: The results showed that 23 isolates were 100% resistant to the commonly used β-lactams, with low susceptibility to fluoroquinolones (resistance rate of 60.87% or more). Colistin (91.30% susceptible) and tigecycline (100% susceptible) were the most active antibiotics against the strains. The MIC values of biocides for the isolates were generally higher, suggesting the potential resistance. Among the tested genes, bla _KPC (95.65%), qacE∆1 (60.87%) and cepA (56.52%) were more prevalent. Three isolates were positive for string test, and 2 isolates carried the specific genes indicative of hypervirulent K. Pneumoniae (hvKp) and caused significantly higher mortality rate, which were ultimately established as hvKp strains and comprised 8.70% of this collection. Conclusion: The coexistence of antibiotic and biocide resistance genes, particularly the emergence of biocide resistance gene-bearing, colistin-resistant CR-hvKP, underscores the need for vigilant surveillance and stringent infection control strategies.