Research Microbiologist (Staff Fellow) — Division of Microbiology

Bijay K. Khajanchi, Ph.D.
(870) 543-7121
[email protected]  

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 About  |  Publications

Background

Dr. Bijay Khajanchi is a research microbiologist in NCTR’s Division of Microbiology. He received his Bachelor’s degree and Master’s degree in microbiology at the University of Dhaka, Bangladesh. Dr. Khajanchi’s research career started at the International Center for Diarrheal Disease and Research, Bangladesh where he conducted research on the molecular epidemiology and antibiotic-resistance mechanisms, including fluoroquinolones and extended spectrum of β-lactamase of Shigella species and pathogenic E. coli. 

In 2005, he received a UNESCO-ASM travel award, that took him to the University of Texas Medical Branch (UTMB) in Galveston.  After completing his short training, he returned and joined the Ph.D. program at UTMB in 2006. Dr. Khajanchi earned his Ph.D. in microbiology and immunology from UTMB in 2011. His Ph.D. research focused on how the bacterial cell-to-cell communication system—known as quorum sensing—regulates the virulence mechanisms of pathogenic bacteria like Aeromonas hydrophila. After completing graduate training, Dr. Khajanchi joined as a postdoctoral fellow in the Department of Pathology and Laboratory Medicine at UT Health Science Center in Houston. During postdoctoral training, he studied the regulatory roles of phosphoenolpyruvate phosphotransferase system (PEP-PTS) in the infectious cycle of Borrelia burgdorferi, a spirochete that causes Lyme disease.

In 2015, Dr. Khajanchi received a Commissioner’s Fellowship and moved to NCTR; where he is actively involved in FDA’s mission-based regulatory research projects in the field of bacterial pathogenesis and antimicrobial-resistance mechanisms. His current research focuses on evaluating plasmid encoded factors in virulence mechanisms and antimicrobial resistances of Salmonella, one of the major foodborne bacterial pathogens in the United States.

 
Research Interests

Dr. Khajanchi’s research interests are to investigate the role of mobile genetic elements (MGEs), including plasmids, in antimicrobial resistance and increased virulence of foodborne bacterial pathogens like Salmonella. In recent studies, he performed and analyzed whole-genome sequencing of different Salmonella isolates from animals, humans, and retail foods to better understand the genetic relatedness, distribution of MGEs, virulence and antimicrobial resistance genes that they carry. Further, he evaluated contribution of Incompatibility Group FIB plasmid encoded factors, such as iron acquisition systems in virulence and antimicrobial resistance of S. enterica. The results of the study showed that the IncFIB plasmids contribute to an increased ability of S. enterica to persist in human intestinal-epithelial cells (Caco-2). His research further identified several iron-regulated genes including those associated with virulence of Salmonella by global transcriptomic and proteomic approaches.

Dr. Khajanchi is interested in developing and implementing new in vitro tools such as 3-dimensional (3D) tissue-culture model systems that more closely mimics in vivo-type conditions than that of 2D cell culture for improved assessment of virulence and host-pathogen interaction of Salmonella. The long-term goals of his research are to discover novel strategies to control the spread of the plasmid encoded virulence and antibiotic resistant factors and to develop new molecular tools to rapidly and efficiently identify emerging foodborne pathogens including Salmonella to promote public health regulatory research.

Professional Societies/National and International Groups

American Society for Microbiology (ASM)
Member
2009 – present 

Arkansas Association of Food Protection
Member
2016   

ASM South Central Branch
Member
2018 – present 

Selected Publications

Draft Genome Sequences of Salmonella enterica Serovar Enteritidis and Kentucky Isolates from Retail Poultry Sources.
Shi Z., Kaldhone P., Khajanchi B., Foley S., and Ricke S.
Genome Announc. 2018, 6(14). 

Evaluation of the Genetics and Functionality of Plasmids in Incompatibility Group I1-Positive Salmonella enterica.
Kaldhone P., Han J., Deck J., Khajanchi B., Nayak R., Foley S., and Ricke S.
Foodborne Pathog Dis. 2018, 15(3):168-176. 

Draft Genome Sequences of Ciprofloxacin-Resistant Salmonella enterica Strains with Multiple-Antibiotic Resistance, Isolated from Imported Foods.
Khan A., Khajanchi B., Khan S., Elkins C., and Foley S.
Genome Announc. 2017 Nov 9, 5(45). 

Draft Genome Sequences of Salmonella enterica Isolates Containing Incompatibility Group I1 Plasmids from Swine, Poultry, and Human Sources.
Kaldhone P., Khajanchi B., Han J., Nayak R., Ricke S., and Foley S.
Genome Announc. 2017, 5(39).

Comparative Genomic Analysis and Characterization of Incompatibility Group FIB Plasmid Encoded Virulence Factors of Salmonella enterica Isolated from Food Sources.
Khajanchi B., Hasan N., Choi S., Han J., Zhao S., Colwell R., Cerniglia C., and Foley S.
BMC Genomics. 2017, 18(1):570. 

Draft Genome Sequences of Four Salmonella enterica Strains Isolated from Turkey-Associated Sources.
Khajanchi B., Han J., Gokulan K., Zhao S., Gies A., and Foley S.
Genome Announc. 2016, 4(5). 

Phosphoenolpyruvate Phosphotransferase System Components Modulate Gene Transcription and Virulence of Borrelia burgdorferi.
Khajanchi B., Odeh E., Gao L., Jacobs M., Philipp M., Lin T., and Norris S.
Infect Immun. 2015, 84(3):754-64. 

Phenotypic and Molecular Characterization of Extended-Spectrum Beta-Lactamase-Producing Escherichia coli in Bangladesh.
Lina T., Khajanchi B., Azmi I., Islam M., Mahmood B., Akter M., Banik A., Alim R., Navarro A., Perez G., Cravioto A., and Talukder K.
PLoS One. 2014, 9(10):e108735. 

Fluoroquinolone Resistance Mechanisms of Shigella flexneri Isolated in Bangladesh.
Azmi I., Khajanchi B., Akter F., Hasan T., Shahnaij M., Akter M., Banik A., Sultana H., Hossain M., Ahmed M., Faruque S., and Talukder K.
PLoS One. 2014, 9(7):e102533. 

Actin Cross-Linking Domain of Aeromonas Hydrophila Repeat in Toxin A (RtxA) Induces Host Cell Rounding and Apoptosis.
Suarez G., Khajanchi B., Sierra J., Erova T., Sha J., and Chopra A.
Gene. 2012, 506(2):369-76. 

Impact of QseBC System in c-di-GMP-Dependent Quorum Sensing Regulatory Network in a Clinical Isolate SSU of Aeromonas hydrophila.
Kozlova E., Khajanchi B., Popov V., Wen J., and Chopra A.
Microb Pathog. 2012, 53(3-4):115-24. 

The Two-Component QseBC Signalling System Regulates In Vitro and In Vivo Virulence of Aeromonas hydrophila.
Khajanchi B., Kozlova E., Sha J., Popov V., and Chopra A.
Microbiology. 2012, 158(Pt 1):259-71. 

Immunomodulatory and Protective Roles of Quorum-Sensing Signaling Molecules N-Acyl Homoserine Lactones During Infection of Mice with Aeromonas hydrophila.
Khajanchi B., Kirtley M., Brackman S., and Chopra A.
Infect Immun. 2011, 79(7):2646-57. 

Quorum Sensing and c-di-GMP-Dependent Alterations in Gene Transcripts and Virulence-Associated Phenotypes in a Clinical Isolate of Aeromonas hydrophila.
Kozlova E., Khajanchi B., Sha J., and Chopra A.
Microb Pathog. 2011, 50(5):213-23. 

Distribution of Virulence Factors and Molecular Fingerprinting of Aeromonas Species Isolates from Water and Clinical Samples: Suggestive Evidence of Water-to-Human Transmission.
Khajanchi B., Fadl A., Borchardt M., Berg R., Horneman A., Stemper M., Joseph S., Moyer N., Sha J., and Chopra A.
Appl Environ Microbiol. 2010, 76(7):2313-25. 

N-Acylhomoserine Lactones Involved in Quorum Sensing Control the Type VI Secretion System, Biofilm Formation, Protease Production, and In Vivo Virulence in a Clinical Isolate of Aeromonas hydrophila.
Khajanchi B., Sha J., Kozlova E., Erova T., Suarez G., Sierra J., Popov V., Horneman A., and Chopra A.
Microbiology. 2009, 155(Pt 11):3518-31. 

Identification of a New Hemolysin from Diarrheal Isolate SSU of Aeromonas hydrophila.
Erova T., Sha J., Horneman A., Borchardt M., Khajanchi B., Fadl A., and Chopra A.
FEMS Microbiol Lett. 2007, 275(2):301-11. 

Further Characterization of a Type III Secretion System (T3SS) and of a New Effector Protein from a Clinical Isolate of Aeromonas hydrophila--Part I.
Sha J., Wang S., Suarez G., Sierra J., Fadl A., Erova T., Foltz S., Khajanchi B., Silver A., Graf J., Schein C., and Chopra A.
Microb Pathog. 2007, 43(4):127-46. 

A Novel Serovar of Shigella dysenteriae from Patients with Diarrhoea in Bangladesh.
Talukder K., Mondol A., Islam M., Islam Z., Dutta D., Khajanchi B., Azmi I., Hossain M., Rahman M., Cheasty T., Cravioto A., Nair G., and Sack D.
J Med Microbiol. 2007, 56(Pt 5):654-8.

Mutations Within the Catalytic Motif of DNA Adenine Methyltransferase (Dam) of Aeromonas hydrophila Cause the Virulence of the Dam-Overproducing Strain to Revert to That of the Wild-Type Phenotype.
Erova T., Fadl A., Sha J., Khajanchi B., Pillai L., Kozlova E., and Chopra A.
Infect Immun. 2006, 74(10):5763-72.