AIMS Antibiotic resistance is a major problem in Salmonella enterica serovar Typhi. Objective of ... more AIMS Antibiotic resistance is a major problem in Salmonella enterica serovar Typhi. Objective of this study was to evaluate the prevalence of XDR Salmonella among local population of Lahore and genotyping of isolates for antibiotic resistant genes. METHODS AND RESULTS A total of 200 blood samples from suspected typhoid fever patients were collected. One hundred and fifty-seven bacterial samples were confirmed as Salmonella Typhi and twenty-three samples were confirmed as Salmonella Paratyphi after biochemical, serological and PCR based molecular characterization. Antibiogram analysis classified 121 (67.2%) Salmonella isolates as MDR and 62 isolates (34.4%) as XDR. The predominant resistance gene was ampC with 47.7% prevalence, followed by gyrA, catA1, tet(A), aac (3)-la, qnrS, blaNDM-1 and blaCTX-M-15 genes in 45.5%, 40%, 21.6%, 18.3%, 11.6%, 2.2% and 0.5% isolates, respectively. Sequence analysis showed the presence of sul1 and dfrA7 gene cassette arrays in twelve class 1 integron integrase positive isolates. CONCLUSION Large number of clinical XDR S. Typhi resistant against third generation cephalosporins have been reported. SIGNIFICANCE AND IMPACT OF STUDY Current study highlights the possible emergence of clinical XDR S. Typhi cases in Lahore, Pakistan. Potential attribution of phenotypic and genotypic XDR cases may help to contribute targeted therapy.
Mercury resistant (HgR) bacteria were screened from industrial effluents and effluents-polluted r... more Mercury resistant (HgR) bacteria were screened from industrial effluents and effluents-polluted rhizosphere soils near to districts Kasur and Sheikhupura, Pakistan. Out of 60 isolates, three bacterial strains, Bacillus sp. AZ-1, Bacillus cereus AZ-2 and Enterobacter cloacae AZ-3 showed Hg-resistance as 20 µg mL-1 of HgCl2 and indole-3-acetic acid (IAA) production as 8-38 µg mL-1. Biochemical and molecular characterization of selected bacteria was confirmed by 16S ribotyping. Mercury resistant genes merA, merB and merE of mer operon in Bacillus spp. were checked by PCR amplification. The merE gene involved in the transportation of elemental mercury (Hg0) via cell membrane was first time cloned into pHLV vector and transformed in C43(DE3) E.coli cells. The recombinant plasmid (pHLMerE) was expressed and purified by nickel (Ni+2) affinity chromatography. Chromatographic techniques viz. thin layer chromatography (TLC), high performance liquid chromatography (HPLC) and gas chromatography–mass spectrometry (GC-MS) confirmed the presence of indole-3-acetic acid (IAA) in supernatant of selected bacteria. The strain E. cloacae AZ-3 detoxified 88% of mercury (Hg+2) from industrial effluent (p<0.05) after immobilization in Na-alginate beads. Finally, Hg-resistant and IAA producing bacterial consortium of two strains, Bacillus sp. AZ-1 and E. cloacae AZ-3, inoculated in mercury amended soil with 20 µg mL-1 HgCl2 resulted 80, 22, 64, 116, 50, 75, 30, and 100% increase as compared to control plants in seed germination, shoot and root length, shoot and root fresh weight, number of pods per plant, number of seeds and weight of seeds respectively of chickpea (Cicer arietinum L.) in pot experiments (p<0.05).
In the current study, mercury-resistant nitrogen fixing bacterial (NFB) strains were isolated by
... more In the current study, mercury-resistant nitrogen fixing bacterial (NFB) strains were isolated by
growing them on selective medium (NFM) to be used as biofertilizers and for the bioremediation of mercury from
polluted soils and waters. Bacterial strains isolated from the soil around root nodules were checked for resistance to
mercury by growing on yeast extract mannitol (YEM) medium supplemented with different concentrations of HgCl2.
Mercury resistant bacterial strains were primarily screened by well plate method. Mercury resistant NFB strains were
further checked for their H2S production by growing on lead acetate (LA) medium. Selected nitrogen fixing and
mercury resistant bacterial strains were characterized using different biochemical tests and found to belong to genera
Pseudomonas, Cronobacter and Bacillus. Quantification of detoxified mercury by selected bacterial strains was done
by using dithizone method. Cronobacter species were found to be significantly the most efficient in the detoxification
of mercury that reached up to 95% (p<0.05).
Mercury resistant Pseudomonas strains were isolated from polluted water, rhizospheric soil and
... more Mercury resistant Pseudomonas strains were isolated from polluted water, rhizospheric soil and
root nodules of different plant species. Selected bacterial isolates showed potential to produce
florescence under UV light and to tolerate heavy metal stress of 10-20 µg/ml HgCl2.
Biochemical characterization revealed all selected bacterial isolates belong to genus
Pseudomonas. A total of 27 bacterial isolates were evaluated for bioremediation of mercury due
to their ability to produce H2S and fix nitrogen. Genomic DNA of 12 Pseudomonas strains was
isolated and their genetic diversity was evaluated using SSR (GACA)4 microsatellite finger
printing. On the basis of banding pattern of PCR amplified products, a phylogenetic tree was
constructed using Minitab 13 software which showed 71%, 46% and 44% homology of SZ-30,
SZ-6 and SZ-8 with strains of cluster 1 and SZ-16 respectively. Results exhibited significant
diversity among selected Pseudomonas strains.
AIMS Antibiotic resistance is a major problem in Salmonella enterica serovar Typhi. Objective of ... more AIMS Antibiotic resistance is a major problem in Salmonella enterica serovar Typhi. Objective of this study was to evaluate the prevalence of XDR Salmonella among local population of Lahore and genotyping of isolates for antibiotic resistant genes. METHODS AND RESULTS A total of 200 blood samples from suspected typhoid fever patients were collected. One hundred and fifty-seven bacterial samples were confirmed as Salmonella Typhi and twenty-three samples were confirmed as Salmonella Paratyphi after biochemical, serological and PCR based molecular characterization. Antibiogram analysis classified 121 (67.2%) Salmonella isolates as MDR and 62 isolates (34.4%) as XDR. The predominant resistance gene was ampC with 47.7% prevalence, followed by gyrA, catA1, tet(A), aac (3)-la, qnrS, blaNDM-1 and blaCTX-M-15 genes in 45.5%, 40%, 21.6%, 18.3%, 11.6%, 2.2% and 0.5% isolates, respectively. Sequence analysis showed the presence of sul1 and dfrA7 gene cassette arrays in twelve class 1 integron integrase positive isolates. CONCLUSION Large number of clinical XDR S. Typhi resistant against third generation cephalosporins have been reported. SIGNIFICANCE AND IMPACT OF STUDY Current study highlights the possible emergence of clinical XDR S. Typhi cases in Lahore, Pakistan. Potential attribution of phenotypic and genotypic XDR cases may help to contribute targeted therapy.
Mercury resistant (HgR) bacteria were screened from industrial effluents and effluents-polluted r... more Mercury resistant (HgR) bacteria were screened from industrial effluents and effluents-polluted rhizosphere soils near to districts Kasur and Sheikhupura, Pakistan. Out of 60 isolates, three bacterial strains, Bacillus sp. AZ-1, Bacillus cereus AZ-2 and Enterobacter cloacae AZ-3 showed Hg-resistance as 20 µg mL-1 of HgCl2 and indole-3-acetic acid (IAA) production as 8-38 µg mL-1. Biochemical and molecular characterization of selected bacteria was confirmed by 16S ribotyping. Mercury resistant genes merA, merB and merE of mer operon in Bacillus spp. were checked by PCR amplification. The merE gene involved in the transportation of elemental mercury (Hg0) via cell membrane was first time cloned into pHLV vector and transformed in C43(DE3) E.coli cells. The recombinant plasmid (pHLMerE) was expressed and purified by nickel (Ni+2) affinity chromatography. Chromatographic techniques viz. thin layer chromatography (TLC), high performance liquid chromatography (HPLC) and gas chromatography–mass spectrometry (GC-MS) confirmed the presence of indole-3-acetic acid (IAA) in supernatant of selected bacteria. The strain E. cloacae AZ-3 detoxified 88% of mercury (Hg+2) from industrial effluent (p<0.05) after immobilization in Na-alginate beads. Finally, Hg-resistant and IAA producing bacterial consortium of two strains, Bacillus sp. AZ-1 and E. cloacae AZ-3, inoculated in mercury amended soil with 20 µg mL-1 HgCl2 resulted 80, 22, 64, 116, 50, 75, 30, and 100% increase as compared to control plants in seed germination, shoot and root length, shoot and root fresh weight, number of pods per plant, number of seeds and weight of seeds respectively of chickpea (Cicer arietinum L.) in pot experiments (p<0.05).
In the current study, mercury-resistant nitrogen fixing bacterial (NFB) strains were isolated by
... more In the current study, mercury-resistant nitrogen fixing bacterial (NFB) strains were isolated by
growing them on selective medium (NFM) to be used as biofertilizers and for the bioremediation of mercury from
polluted soils and waters. Bacterial strains isolated from the soil around root nodules were checked for resistance to
mercury by growing on yeast extract mannitol (YEM) medium supplemented with different concentrations of HgCl2.
Mercury resistant bacterial strains were primarily screened by well plate method. Mercury resistant NFB strains were
further checked for their H2S production by growing on lead acetate (LA) medium. Selected nitrogen fixing and
mercury resistant bacterial strains were characterized using different biochemical tests and found to belong to genera
Pseudomonas, Cronobacter and Bacillus. Quantification of detoxified mercury by selected bacterial strains was done
by using dithizone method. Cronobacter species were found to be significantly the most efficient in the detoxification
of mercury that reached up to 95% (p<0.05).
Mercury resistant Pseudomonas strains were isolated from polluted water, rhizospheric soil and
... more Mercury resistant Pseudomonas strains were isolated from polluted water, rhizospheric soil and
root nodules of different plant species. Selected bacterial isolates showed potential to produce
florescence under UV light and to tolerate heavy metal stress of 10-20 µg/ml HgCl2.
Biochemical characterization revealed all selected bacterial isolates belong to genus
Pseudomonas. A total of 27 bacterial isolates were evaluated for bioremediation of mercury due
to their ability to produce H2S and fix nitrogen. Genomic DNA of 12 Pseudomonas strains was
isolated and their genetic diversity was evaluated using SSR (GACA)4 microsatellite finger
printing. On the basis of banding pattern of PCR amplified products, a phylogenetic tree was
constructed using Minitab 13 software which showed 71%, 46% and 44% homology of SZ-30,
SZ-6 and SZ-8 with strains of cluster 1 and SZ-16 respectively. Results exhibited significant
diversity among selected Pseudomonas strains.
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growing them on selective medium (NFM) to be used as biofertilizers and for the bioremediation of mercury from
polluted soils and waters. Bacterial strains isolated from the soil around root nodules were checked for resistance to
mercury by growing on yeast extract mannitol (YEM) medium supplemented with different concentrations of HgCl2.
Mercury resistant bacterial strains were primarily screened by well plate method. Mercury resistant NFB strains were
further checked for their H2S production by growing on lead acetate (LA) medium. Selected nitrogen fixing and
mercury resistant bacterial strains were characterized using different biochemical tests and found to belong to genera
Pseudomonas, Cronobacter and Bacillus. Quantification of detoxified mercury by selected bacterial strains was done
by using dithizone method. Cronobacter species were found to be significantly the most efficient in the detoxification
of mercury that reached up to 95% (p<0.05).
root nodules of different plant species. Selected bacterial isolates showed potential to produce
florescence under UV light and to tolerate heavy metal stress of 10-20 µg/ml HgCl2.
Biochemical characterization revealed all selected bacterial isolates belong to genus
Pseudomonas. A total of 27 bacterial isolates were evaluated for bioremediation of mercury due
to their ability to produce H2S and fix nitrogen. Genomic DNA of 12 Pseudomonas strains was
isolated and their genetic diversity was evaluated using SSR (GACA)4 microsatellite finger
printing. On the basis of banding pattern of PCR amplified products, a phylogenetic tree was
constructed using Minitab 13 software which showed 71%, 46% and 44% homology of SZ-30,
SZ-6 and SZ-8 with strains of cluster 1 and SZ-16 respectively. Results exhibited significant
diversity among selected Pseudomonas strains.
growing them on selective medium (NFM) to be used as biofertilizers and for the bioremediation of mercury from
polluted soils and waters. Bacterial strains isolated from the soil around root nodules were checked for resistance to
mercury by growing on yeast extract mannitol (YEM) medium supplemented with different concentrations of HgCl2.
Mercury resistant bacterial strains were primarily screened by well plate method. Mercury resistant NFB strains were
further checked for their H2S production by growing on lead acetate (LA) medium. Selected nitrogen fixing and
mercury resistant bacterial strains were characterized using different biochemical tests and found to belong to genera
Pseudomonas, Cronobacter and Bacillus. Quantification of detoxified mercury by selected bacterial strains was done
by using dithizone method. Cronobacter species were found to be significantly the most efficient in the detoxification
of mercury that reached up to 95% (p<0.05).
root nodules of different plant species. Selected bacterial isolates showed potential to produce
florescence under UV light and to tolerate heavy metal stress of 10-20 µg/ml HgCl2.
Biochemical characterization revealed all selected bacterial isolates belong to genus
Pseudomonas. A total of 27 bacterial isolates were evaluated for bioremediation of mercury due
to their ability to produce H2S and fix nitrogen. Genomic DNA of 12 Pseudomonas strains was
isolated and their genetic diversity was evaluated using SSR (GACA)4 microsatellite finger
printing. On the basis of banding pattern of PCR amplified products, a phylogenetic tree was
constructed using Minitab 13 software which showed 71%, 46% and 44% homology of SZ-30,
SZ-6 and SZ-8 with strains of cluster 1 and SZ-16 respectively. Results exhibited significant
diversity among selected Pseudomonas strains.