المؤلفون: Maurya, Anand Prakash¹, Chanda, Debadatta Dhar², Bora, Debajyoti³, Das Talukdar, Anupam⁴, Chakravarty, Atanu³, Bhattacharjee, Amitabha¹

المصدر: Microbial Drug Resistance: Mechanism, Epidemiology, & Disease. Mar2017, Vol. 23 Issue 2, p133-138. 6p.

مصطلحات موضوعية: *GENETIC transcription, *ESCHERICHIA coli, *CEPHALOSPORINS, *BETA lactamases, *GENE expression, *ANTIBIOTICS

مستخلص: The expression of extended-spectrum beta-lactamases directly interferes with the treatment options in a clinical setting. It is not clearly defined why bacteria acquire multiple beta-lactamases and how they are being expressed in antibiotic stress. With this key question, the study was designed to understand the transcriptional response in Escherichia coli harboring multiple blaESBLs against different oxyimino-cephalosporin stress. A total of 169 consecutive, nonduplicate oxyimino-cephalosporin-resistant isolates of E. coli were screened and were ESBL positive. Among them six isolates were found to harbor multiple beta-lactamase genes and we, as per our objective, selected them for this study. Molecular characterization was done by multiplex polymerase chain reaction (PCR) assay. Minimum inhibitory concentration, transcriptional expression, transferability, and plasmid incompatibility typing of multiple blaESBLs were carried out. Plasmid stability and antibiotic susceptibility of donor and transconjugants were performed. A total of six isolates were found to be harboring multiple ESBL genes and MIC above the breakpoint level against all the tested antibiotics. Quantitative real-time PCR showed that in basal level without antibiotic stress, SHV-148 expressed more, but with ceftriaxone stressed, expression of CTX-M-15 and SHV-148 was high. In case of PER-1, expression was high with ceftazidime stress. blaESBLs were horizontally transferable and originated through multiple inc types. Plasmids were stable till 115 serial passages. Pulsed-field gel electrophoresis results showed that multiple ESBL genes were spread through six pulsotypes. Our study concludes that acquisition of multiple ESBL genes in E. coli was a specific adaptation for survival against multiple oxyimino-cephalosporin stress in this clinical setting. [ABSTRACT FROM AUTHOR]

المؤلفون: Deshamukhya, Chandrayee¹, Bhowmik, Deepshikha¹, (Chanda), Debadatta Dhar², Bhattacharjee, Amitabha¹ ab0404@gmail.com

المصدر: Indian Journal of Medical Research. May2023, Vol. 157 Issue 5, p477-481. 8p.

مصطلحات موضوعية: *STAPHYLOCOCCUS aureus

المؤلفون: Hazarika, Monalisha¹ (AUTHOR), Wangkheimayum, Jayalaxmi¹ (AUTHOR), Nath, Kathakali¹ (AUTHOR), Bhowmik, Deepshikha¹ (AUTHOR), Singha, K. Melson² (AUTHOR), Chanda, Debadatta Dhar² (AUTHOR), Bhattacharjee, Amitabha¹ (AUTHOR) ab0404@gmail.com

المصدر: Current Microbiology. Aug2023, Vol. 80 Issue 8, p1-6. 6p.

مستخلص: Staphylococcus aureus is a global pathogen and is responsible for causing severe life-threatening infections. The current study was designed to investigate transcriptional expression of different core, regulatory, and accessory genes within vanB operon under differential exposure of vancomycin and teicoplanin. Four isolates selected for the study, were confirmed to harbour vanB gene in which three isolates showed MIC breakpoint above 16 µg/ml and one isolate above 8 µg/ml against vancomycin while teicoplanin showed higher MIC breakpoint as compared to vancomycin. Antibiotic susceptibility results showed that these isolates were susceptible towards imipenem and linezolid. Transcriptional expressional analysis of the core gene of vanB operon showed that expression of vanB is increased under vancomycin stress but is inversely proportional to increase in the concentration of the vancomycin while under teicoplanin stress the expression of vanB showed no significant pattern. Similar expressional pattern was found for vanH gene for both the glycopeptides. In case of vanX, expression was significantly increased at 1 µg/ml exposure of vancomycin, however, no pattern could be observed in case of teicoplanin stress. In case of regulatory gene, vanR, significant increase in expression was observed under vancomycin and teicoplanin stress of 1 µg/ml, however vanS, showed significant increase in the expression under 1 µg/ml of vancomycin. The accessory gene, vanY showed marginal increase in expression under both the antibiotic, while in case of vanW, the expressional pattern was found to be inversely proportional to the increasing antibiotic concentration. [ABSTRACT FROM AUTHOR]

المؤلفون: Paul, Deepjyoti¹, Maurya, Anand Prakash¹, Chanda, Debadatta Dhar², Sharma, Gauri Dutt³, Chakravarty, Atanu², Bhattacharjee, Amitabha¹ ab0404@gmail.com

المصدر: Indian Journal of Medical Research. Jun2016, Vol. 143 Issue 6, p826-829. 4p.

مصطلحات موضوعية: *PSEUDOMONAS aeruginosa, *INFECTIOUS disease transmission

مستخلص: A letter to the editor is presented on a study to characterize blaNDM-1 in clinical isolates of Pseudomonas aeruginosa and their transmission dynamics.

المؤلفون: Wangkheimayum, Jayalaxmi¹ (AUTHOR), Paul, Deepjyoti¹ (AUTHOR), Chanda, Debadatta Dhar² (AUTHOR), Melson Singha, K.² (AUTHOR), Bhattacharjee, Amitabha¹ (AUTHOR) ab0404@gmail.com

المصدر: Infection, Genetics & Evolution. Mar2022, Vol. 98, pN.PAG-N.PAG. 1p.

مصطلحات موضوعية: *KANAMYCIN, *ESCHERICHIA coli, *STRESS concentration, *MOLECULES, *CONCENTRATION gradient, *ANTIBIOTICS, *AMIKACIN

مستخلص: We aimed to design and analyse expressional response of endogenous and exogenous 16S rRNA methyl transferase genes under sub inhibitory concentration stress of different clinically relevant aminoglycoside antibiotics in Escherichia coli to identify an endogenous marker. One hundred twenty nine aminoglycoside resistant E. coli of clinical origin were collected for detection of 16S rRNA methyl transferase genes by PCR assay and each gene type was cloned within E. coli JM107. Parent isolates were subjected to plasmid elimination by SDS treatment. Expression analysis of both acquired and endogenous 16S rRNA methyl transferase genes were performed by quantitative real-time PCR in clones and parent isolates under aminoglycoside stress (4 mg/L). Majority of the isolates were harbouring rmtC (35/129), followed by rmtB (32/129), rmtA (21/129), rmtE (13/129), armA (11/129) rmtF (9/129) and rmtH (8/129). Plasmid was successfully eliminated for all the isolates with 6% of SDS. Expression analysis indicates that kanamycin, tobramycin and netilmicin stress could increase the expression of 16S rRNA methyltransferese genes. In the presence of kanamycin stress the expression of rsmI was consistently elevated for all the wild type isolates and clones tested. Except for isolates harbouring rmtB and rmtC expression of rsmE and rsmF was increased in the presence of all aminoglycosides. For all the cured mutants it was apparently observed that expression of endogenous methyl transferases were marginally increased. Elevated expression of constitutive rsmI can be used as a potential biomarker for detection of acquired 16S rRNA methyl transferase mediated aminoglycoside resistance by using sub inhibitory concentration of kanamycin as signal molecule. • This study underscores genetic interplay between exogenous and endogenous methyl transferase genes. • The transcriptional response of different endogenous and exogenous methyl transferases under concentration gradient aminoglycoside stress. • Identifies rsmI as a reporter for acquired 16S rRNA methyl transferase mediated aminoglycoside resistance using kanamycin as signal molecule. [ABSTRACT FROM AUTHOR]

المؤلفون: Elizabeth, Rajkumari¹ (AUTHOR), Baishya, Somorita² (AUTHOR), Kalita, Bubul¹ (AUTHOR), Wangkheimayum, Jayalaxmi¹ (AUTHOR), Choudhury, Manabendra Dutta² (AUTHOR), Chanda, Debadatta Dhar³ (AUTHOR), Bhattacharjee, Amitabha¹ (AUTHOR) ab0404@gmail.com

المصدر: Scientific Reports. 1/25/2022, Vol. 12 Issue 1, p1-8. 8p.

مصطلحات موضوعية: *COLISTIN, *ESCHERICHIA coli, *INAPPROPRIATE prescribing (Medicine), *GENE regulatory networks, *POLYMYXIN

مستخلص: Colistin resistance has increased due to the increasing and inappropriate use of this antibiotic. The mechanism involves modification of lipid A with phosphoethanolamine (PEtN) and/or 4-amino-4deoxy-l-arabinose (L-Ara4N). EptA and eptB catalyze the transfer of phosphoethanolamine to lipid A. In this study, gene network was constructed to find the associated genes related to colistin resistance, and further in vitro validation by transcriptional analysis was performed. In silico studies showed that eptB gene is a highly interconnected node in colistin resistance gene network. To ascertain these findings twelve colistin-resistant clinical isolates of Escherichia coli were selected in which five were harboring the plasmid-mediated mcr-1. Screening for colistin resistance was performed by broth microdilution (BMD) method and Rapid polymyxin NP test. PCR confirmed the presence of the eptA and eptB genes in all isolates and five isolates were harboring mcr-1. Transcriptional expression in five isolates harboring mcr-1, showed an enhanced expression of eptB when exposed under sub-inhibitory colistin stress. The present study for the first time highlighted genetic interplay between mcr-1 and eptA and eptB under colistin exposure. [ABSTRACT FROM AUTHOR]

المؤلفون: Choudhury, Nargis Alom¹, Paul, Deepjyoti¹, Das, Bhaskar Jyoti¹, Chanda, Debadatta Dhar², Bhattacharjee, Amitabha¹ ab0404@gmail.com

المصدر: Journal of Microbiology & Infectious Diseases. Jun2021, Vol. 11 Issue 2, p74-80. 7p.

مصطلحات موضوعية: *CONCENTRATION gradient, *STRESS concentration, *ESCHERICHIA coli, *AMINOGLYCOSIDES

مستخلص: Objectives: The current study was aimed to investigate the adaptability and stability of blaNDM-4 within a broad host range and transcriptional response. Methods: Six isolates of Escherichia coli, harboring blaNDM-4 were confirmed by PCR sequencing of the whole gene. Transformation and conjugation assay were carried out and plasmid incompatibility was determined by PCR assay. The serial passage was done for consecutive 70 days without any antibiotic pressure for both parent strain and transformants. Transcriptional expression of blaNDM-4 within a broad host range against concentration gradient imipenem stress was studied. Results: IncX3 plasmid encoding blaNDM-4 was successfully transferred in six different hosts when imipenem (0.5 µg/ml) screen agar was used for the selection of transformants. It was also found to harbor resistance for aminoglycosides and quinolone. When checked for stability, it was observed that the plasmid was successfully expanded within all six recipients for 55th serial passages. Transcriptional expression with IncX3 was random but at a consistent level for wild type and without concentration gradient stress of imipenem. Transcriptional expression with NDM gene was variable for parent isolates though for new hosts it was showing randomly increased patterns in Proteus, E. coli, and DH5a. Conclusion: The present study could highlight that external carbapenem pressure helps in the maintenance and expression of blaNDM-4 within different host range. This study is of epidemiological significance and will help in tracking the genetic vehicle responsible for their transmission by restricting their spread. [ABSTRACT FROM AUTHOR]

المؤلفون: Bhowmik, Deepshikha¹ (AUTHOR), Chetri, Shiela¹ (AUTHOR), Pandey, Piyush¹ (AUTHOR), Das, Bhaskar Jyoti¹ (AUTHOR), Wangkheimayum, Jayalaxmi¹ (AUTHOR), Choudhury, Nargis Alom¹ (AUTHOR), Singha, K. Melson² (AUTHOR), Chanda, Debadatta Dhar² (AUTHOR), Bhattacharjee, Amitabha¹ (AUTHOR) ab0404@gmail.com

المصدر: Current Microbiology. 2021, Vol. 78 Issue 2, p528-533. 6p.

مصطلحات موضوعية: *METHICILLIN-resistant staphylococcus aureus, *OXACILLIN, *REGULATOR genes, *GENES, *GENE expression

مستخلص: The psm-mec element and other regulatory factors such as sarA, agrA, and RNAIII are responsible for maintaining the genetic framework for enhanced virulence of MRSA. psm-mec is found predominantly in the staphylococcal cassette chromosome (SCCmec). sarA, agrA, and RNAIII control gene expression to facilitate adaptation in certain environment. Genome-wide approaches have shown that expression of virulence factors is frequently regulated at transcriptional, translational level, and mRNA degradation level. In this study, transcriptional responses of psm-mec gene in accordance with other regulatory factors sarA, agrA, and RNAIII were observed under normal conditions as well as when exposed to 2 μg/ml and 6 μg/ml of oxacillin stress. One-way t-test was carried out for analysing RQ values obtained through real-time PCR. This study showed downregulation of psm-mec gene and upregulation of other regulatory genes at lower concentration of oxacillin. However, this was reverse when exposed against higher concentration of oxacillin. It was observed from the study that the expression of virulence factors were dependent on each other under different concentration of oxacillin. Thus, this study highlights that psm-mec, sarA, agrA, and RNAIII gene are under direct control of antibiotic pressure in a concentration-dependent manner. [ABSTRACT FROM AUTHOR]

المؤلفون: Wangkheimayum, Jayalaxmi¹ (AUTHOR), Bhattacharjee, Mohana¹ (AUTHOR), Das, Bhaskar Jyoti¹ (AUTHOR), Singha, K. Melson² (AUTHOR), Chanda, Debadatta Dhar² (AUTHOR), Bhattacharjee, Amitabha¹ (AUTHOR) ab0404@gmail.com

المصدر: BMC Infectious Diseases. 7/25/2020, Vol. 20 Issue 1, p1-5. 5p. 2 Charts.

مصطلحات موضوعية: *RIBOSOMAL RNA, *ESCHERICHIA coli, *METHYLTRANSFERASES, *CARBAPENEMASE, *KLEBSIELLA

مصطلحات جغرافية: INDIA

مستخلص: Background: This study aimed to identify ten different 16S rRNA methyltransferase genes (rmtA, rmtB, rmtC, rmtD, armA, rmtF, npmA, rmtH, rmtE and rmtG) and their coexisting ESBL and carbapenemase with the emergence of three E.coli clones within a single study centre.Methods: A total of 329 non-duplicate E.coli isolates were studied to detect the presence of 16S rRNA methyltransferases along with β-lactamases (TEM, SHV, OXA, VEB, GES, PER,CTX-M types, NDM, OXA-48,VIM, IMP and KPC) using PCR assay. Horizontal transferability were validated by transformation and conjugation analysis. Plasmid incompatibility typing and MLST analysis was also performed.Results: A total of 117 isolates were found to be resistant to at least one of the aminoglycoside antibiotics. It was observed that 77 (65.8%) were positive for 16S rRNA methyltransferases. Among them thirty nine isolates were found to harbour only blaCTX-M-15, whereas combination of genes were observed in three isolates (blaVEB+ blaCTX-M-15 in 2 isolates and blaPER + blaCTX-M-15 in 1 isolate). blaNDM and blaOXA-48 like genes were found in 23 and 9 isolates, respectively. All the resistance genes were conjugatively transferable, and incompatibility typing showed multiple 16S rRNA methyltransferase genes were originated from a single Inc. I1 group. MLST analysis detected 3 clones of E.coliST4410, ST1341 and ST3906.Conclusion: The present study identified emergence of three clones of E.coli, resistant to aminoglycoside -cephalosporin- carbapenem. This warrants immediate measures to trace their transmission dynamics in order to slow down their spread in clinical setting. [ABSTRACT FROM AUTHOR]

المؤلفون: Chetri, Shiela¹ (AUTHOR), Das, Bhaskar Jyoti¹ (AUTHOR), Bhowmik, Deepshikha¹ (AUTHOR), Chanda, Debadatta Dhar² (AUTHOR), Chakravarty, Atanu² (AUTHOR), Bhattacharjee, Amitabha¹ (AUTHOR) ab0404@gmail.com

المصدر: BMC Research Notes. 3/19/2020, Vol. 13 Issue 1, p1-7. 7p. 1 Diagram, 2 Graphs.

مصطلحات موضوعية: *NOSOCOMIAL infections, *ESCHERICHIA coli, *CONCENTRATION gradient, *DRUG resistance in bacteria, *BETA lactam antibiotics, *SOCKS, *KLEBSIELLA

مستخلص: Objective: The present study was carried out to investigate the transcriptional response of marA (Multiple antibiotic resistance A gene), soxS (Superoxide S gene) and rob (Right-origin-binding gene) under carbapenem stress. Results: 12 isolates were found over-expressing AcrAB-TolC efflux pump system and showed reduced expression of OmpF (Outer membrane porin) gene were selected for further study. Among them, over expression of marA and rob was observed in 7 isolates. Increasing pattern of expression of marA and rob against meropenem was observed. The clones of marA and rob showed reduced susceptibility towards carbapenems. [ABSTRACT FROM AUTHOR]