@article{mbs:/content/journal/micro/10.1099/mic.0.065052-0, author = "Srinivasan, Vijaya Bharathi and Mondal, Amitabha and Venkataramaiah, Manjunath and Chauhan, Neeraj Kumar and Rajamohan, Govindan", title = "Role of oxyRKP, a novel LysR-family transcriptional regulator, in antimicrobial resistance and virulence in Klebsiella pneumoniae", journal= "Microbiology", year = "2013", volume = "159", number = "Pt_7", pages = "1301-1314", doi = "https://doi.org/10.1099/mic.0.065052-0", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.065052-0", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", abstract = " Klebsiella pneumoniae is a Gram-negative bacillus that causes serious infections in immunocompromised human hosts and exhibits significant multidrug resistance. In this study, we identified a novel lysR-family regulator (designated oxyR KP) in the genome of K. pneumoniae NTUH-K2044 whose functions have remained enigmatic so far. Functional characterization of the putative lysR regulator oxyR KP with respect to cellular physiology and antimicrobial susceptibility was performed by generating an isogenic mutant, ΔoxyR KP in a hypervirulent clinical isolate of K. pneumoniae. The K. pneumoniae oxyR KP mutant was sensitive to hyperosmotic and bile conditions. Disruption of oxyR KP increased the susceptibility of K. pneumoniae to oxidative (0.78947 mM hydrogen peroxide) and nitrosative (30 mM acidified nitrite) stress by ~1.4-fold and ~10-fold, respectively. Loss of the Klebsiella regulator led to a decrease in the minimum inhibitory concentrations for chloramphenicol (10-fold), erythromycin (6-fold), nalidixic acid (>50-fold) and trimethoprim (10-fold), which could be restored following complementation. The relative change in expression of resistance–nodulation–cell division super family (RND) efflux gene acrB was decreased by approximately fivefold in the oxyR KP mutant as evidenced by qRT-PCR. In a Caenorhabditis elegans model, the oxyR KP mutant exhibited significantly (P<0.01) lower virulence. Overall, results detailed in this report reflect the pleiotropic role of the oxyR KP signalling system and diversity of the resistance determinants in hypervirulent K1 serotype K. pneumoniae NTUH-K2044.", }