Priyabrata Mohanty

Publications (4) View all

• Article: Clinical isolates of Vibrio fluvialis from Kolkata, India, obtained during 2006: plasmids, the qnr gene and a mutation in gyrase A as mechanisms of multidrug resistance.

  Rochika Singh, Neha Rajpara, Jyoti Tak, Arati Patel, Priyabrata Mohanty, Kittappa Vinothkumar, Goutam Chowdhury, Thandavarayan Ramamurthy, Amit Ghosh, Ashima Kushwaha Bhardwaj
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  ABSTRACT: Resistance profiles and their correlation with genetic factors were investigated in 12 isolates of Vibrio fluvialis obtained from hospitalized patients in Kolkata, India, in 2006. All the strains displayed drug resistance with varying antibiograms. However, resistance to ampicillin and neomycin was common to all of them. Three isolates harboured plasmids carrying drug-resistance genes that could be transferred to recipient strains by conjugation and transformation. PCR results indicated the absence of class 1 integrons and SXT elements in these isolates. A mutation in gyrase A (serine 83→isoleucine) and the presence of the qnrB1 gene were found to contribute towards quinolone resistance. In the 12 isolates, the qnrB1 gene was associated only with two plasmid-bearing isolates, L10734 and L9978, which displayed resistance to quinolones. The gene was transferable during transformation and conjugation, indicating that it was plasmid-borne. Taken together, these data indicate that plasmids, the qnrB1 gene and a mutation in gyrase A were responsible for the observed drug resistance in these strains. To the best of our knowledge, this is the first report of the presence of the qnrB1 allele in V. fluvialis isolates from India.
  Journal of Medical Microbiology 03/2012; 61(Pt 3):369-74. · 2.50 Impact Factor
• Article: Bacterial Efflux Pumps Involved in Multidrug Resistance and their Inhibitors: Rejuvinating the Antimicrobial Chemotherapy.

  Ashima K Bhardwaj, Priyabrata Mohanty
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  ABSTRACT: Active efflux of antibiotics is one of the major mechanisms of drug resistance in bacteria. The efflux process is mediated by membrane transporters with a large variety of unrelated compounds as their substrates. Though these pumps are responsible for the low intrinsic resistance of a bacterium to a drug, their overexpression, accumulation of mutations in these proteins and their synergy with other drug resistance mechanisms hampers effective antimicrobial treatment. As efflux pumps have been reported to play vital roles in mediating multidrug resistance in clinical isolates from varied geographic locations and varied populations, the inhibition of efflux pumps appears to be an attractive approach to combat the problem of drug resistance. Efflux pump inhibitors can be utilized for increasing the antibiotic concentration inside a pathogenic cell making these drugs more effective, reduce the accumulation of other resistance mechanisms in a cell and for diagnostic purposes to evaluate the presence and contribution of the efflux mechanism in a pathogen. A large number of inhibitors have been discovered and patented in last two decades but the process of discovery, testing and commercialization is rather slow. Some of the important inhibitors include the energy decouplers, phenothiazines, analogs of popular antibiotics, inhibitors of serotonin re-uptake, to name a few, that have been used as adjuvants in the antimicrobial chemotherapy to potentiate the activity of some important antimicrobials in deadly pathogens that have worried the mankind since long. This review describes the role of efflux pumps in governing the resistance phenotype of a pathogen, efflux pumps found in bacteria and the efflux pump inhibitors that have been studied and patented so far.
  Recent Patents on Anti-Infective Drug Discovery 02/2012; 7(1):73-89.
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  Available from: Priyabrata Mohanty

  Article: Role of H- and D- MATE-type transporters from multidrug resistant clinical isolates of Vibrio fluvialis in conferring fluoroquinolone resistance.

  Priyabrata Mohanty, Arati Patel, Ashima Kushwaha Bhardwaj
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  ABSTRACT: The study seeks to understand the role of efflux pumps in multidrug resistance displayed by the clinical isolates of Vibrio fluvialis, a pathogen known to cause cholera-like diarrhoea. Two putative MATE family efflux pumps (H- and D-type) were PCR amplified from clinical isolates of V. fluvialis obtained from Kolkata, India, in 2006 and sequenced. Bioinformatic analysis of these proteins was done to predict protein structures. Subsequently, the genes were cloned and expressed in a drug hypersusceptible Escherichia coli strain KAM32 using the vector pBR322. The recombinant clones were tested for the functionality of the efflux pump proteins by MIC determination and drug transport assays using fluorimeter. The sequences of the genes were found to be around 99% identical to their counterparts in V. cholerae. Protein structure predicting servers TMHMM and I-TASSER depicted ten-twelve membrane helical structures for both type of pumps. Real time PCR showed that these genes were expressed in the native V. fluvialis isolates. In the drug transport assays, the V. fluvialis clinical isolates as well as recombinant E. coli harbouring the efflux pump genes showed the energy-dependent and sodium ion-dependent drug transport activity. KAM32 cells harbouring the recombinant plasmids showed elevated MIC to the fluoroquinolones, norfloxacin and ciprofloxacin but H-type pumps VCH and VFH from V. cholerae and V. fluvialis respectively, showed decreased MIC to aminoglycosides like gentamicin, kanamycin and streptomycin. Decrease in MIC was also observed for acriflavin, ethidium bromide, safranin and nalidixic acid. Increased resistance towards fluoroquinolones exhibited due to these efflux pumps from multidrug resistant clinical isolates of V. fluvialis implies that treatment procedure may become more elaborate for this simple but highly infectious disease. To the best of our knowledge, this is the first report of cloning and characterization of efflux pumps from multidrug resistant clinical isolates of V. fluvialis.
  PLoS ONE 01/2012; 7(4):e35752. · 4.09 Impact Factor
• Article: Incidence, Serotype, Antibiogram and Toxigenicity of Vibrio cholerae during 2000, Six Month after the Super Cyclone, 1999 in Orissa, India

  H.K. Khuntia, S.K. Samal, S.R. Nayak, A.K. Sarangi, P. Mohanty, S.K. Kar, B.B. Pal
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  ABSTRACT: This study was undertaken to analyze the cholera situation during July to November 2000 six month after the super-cyclone in saline tract of Orissa, India. Hundred ninety eight rectal swabs collected from hospitalized diarrhoea cases were subjected for bacteriological analysis. Of the 162 culture positive cases, V.cholerae 81 (50%), EPEC 1 (0.6 %), EHEC 3 (1.8%), EAggEC 2 (1.2%), Shigella flexneri 3 (1.8%) and Salmonella spp. 4 (2.5%) were isolated. Quadriplex and monoplex PCR assay revealed that, 51(31.5%) were V. cholerae O1 and 30 (18.5%) V. cholerae O139; carried ctxA, tcpA (Biotype El Tor), zot, ace and toxR except 3 V. cholerae O139 negative for ctxA gene. Incidence of V. cholerae six month after the super cyclone was found significantly higher than the pre-cyclonic period (P < 0.5). Strains of V. cholerae O1 was observed to be resistant to nalidixic acid, furazolidone, streptomycin, co-trimoxazole, ampicillin & neomycin. Except for co–trimoxazole, the resistant pattern of O139 was identical with that of O1 strains. The study revealed that V.cholerae O1 & O139 were the potential organism for cholera outbreaks in coastal Orissa, where ctxA & tcpA genes played a major role for pathogenesis. Incidence and emergence of fluroquinolone resistant V. cholerae O1 and O139 and nalidixic acid resistant O139 sero group should be closely monitored.
  Journal of Pure and Applied Microbiology 03/2008; 2(Apr 2008-1). · 0.06 Impact Factor