Varying levels of disinfectant resistance among invasive Klebsiella pneumoniae isolates

Disinfectants are essential agents for pathogen/infection control in medical settings. As antibiotic resistance accelerates, disinfectants become more crucial for pathogen control. Klebsiella pneumoniae, a gram-negative bacterium with extensive antibiotic resistance, is a common cause of devastating infections that are mostly acquired in hospitals where disinfectants are regularly applied. Hospital-acquired or nosocomial infections are among the healthcare system's most significant challenges. We hypothesized that nosocomial pathogens could survive regular disinfection since these bacteria are commonly identified in medical settings despite the use of disinfectants. We tested this hypothesis by treating 11 invasive K. pneumoniae strains isolated from the human bloodstream with trichloroisocyanuric acid (TCCA), a widely used antimicrobial agent in medical settings. Temporary treatment of K. pneumoniae with 32 mg/L TCCA (as would occur in a hospital setting) for 1 hr did not completely eradicate 10 of the 11 isolates. Cultivation for 24 hr in the presence of TCCA at 700 mg/L, more than 20 times the typical concentration for the sanitation purpose, revealed two invasive K. pneumoniae isolates with significant resistance. Subsequent polymerase chain reaction (PCR) amplification found no close association between TCCA resistance and previously identified disinfectant-resistant genes. Our work has thus indicated that K. pneumoniae resistance to TCCA might be attributed to a new mechanism(s) other than the known disinfectant-resistant genes.