Ashraf A Khan

Summary

Affiliation: Food and Drug Administration
Country: USA

Publications

  1. ncbi request reprint Characterization of United States outbreak isolates of Vibrio parahaemolyticus using enterobacterial repetitive intergenic consensus (ERIC) PCR and development of a rapid PCR method for detection of O3:K6 isolates
    Ashraf A Khan
    Division of Microbiology, US Food and Drug Administration, NCTR, Jefferson, AR 72079, USA
    FEMS Microbiol Lett 206:209-14. 2002
  2. pmc Molecular cloning, nucleotide sequence, and expression in Escherichia coli of a hemolytic toxin (aerolysin) gene from Aeromonas trota
    A A Khan
    Division of Microbiology, Food and Drug Administration, Jefferson, Arkansas 72079, USA
    Appl Environ Microbiol 64:2473-8. 1998
  3. ncbi request reprint Classification of a polycyclic aromatic hydrocarbon-metabolizing bacterium, Mycobacterium sp. strain PYR-1, as Mycobacterium vanbaalenii sp. nov
    Ashraf A Khan
    Division of Microbiology, National Center for Toxicological Research, US Food and Drug Administration, 3900 NCTR Road, Jefferson, AR 72079, USA
    Int J Syst Evol Microbiol 52:1997-2002. 2002
  4. ncbi request reprint Identification of Aeromonas trota (hybridization group 13) by amplification of the aerolysin gene using polymerase chain reaction
    A A Khan
    National Center for Toxicological Research, Food and Drug Administration, Jefferson, AR 72079, USA
    Mol Cell Probes 13:93-8. 1999
  5. ncbi request reprint Identification of predominant human and animal anaerobic intestinal bacterial species by terminal restriction fragment patterns (TRFPs): a rapid, PCR-based method
    A A Khan
    Division of Microbiology, Food and Drug Administration, Jefferson, AR 72079, USA
    Mol Cell Probes 15:349-55. 2001
  6. ncbi request reprint Detection of multidrug-resistant Salmonella typhimurium DT104 by multiplex polymerase chain reaction
    A A Khan
    Division of Microbiology, Food and Drug Administration, National Center for Toxicological Research, Jefferson, AR 72079, USA
    FEMS Microbiol Lett 182:355-60. 2000
  7. doi request reprint Detection and characterization of virulence genes and integrons in Aeromonas veronii isolated from catfish
    Mohamed Nawaz
    Division of Microbiology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, AR 72079, USA
    Food Microbiol 27:327-31. 2010
  8. ncbi request reprint Novel organization of genes in a phthalate degradation operon of Mycobacterium vanbaalenii PYR-1
    Robin L Stingley
    Division of Microbiology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, AR 72079, USA
    Microbiology 150:3749-61. 2004
  9. ncbi request reprint Molecular characterization of cytochrome P450 genes in the polycyclic aromatic hydrocarbon degrading Mycobacterium vanbaalenii PYR-1
    Barbara Brezna
    Division of Microbiology, National Center for Toxicological Research, US Food and Drug Administration, 3900 NCTR Road, Jefferson, AR 72079, USA
    Appl Microbiol Biotechnol 71:522-32. 2006
  10. ncbi request reprint Isolation and characterization of tetracycline-resistant Citrobacter spp. from catfish
    Mohamed Nawaz
    Division of Microbiology, National Center for Toxicological Research, Jefferson, AR 72079, USA
    Food Microbiol 25:85-91. 2008

Collaborators

Detail Information

Publications42

  1. ncbi request reprint Characterization of United States outbreak isolates of Vibrio parahaemolyticus using enterobacterial repetitive intergenic consensus (ERIC) PCR and development of a rapid PCR method for detection of O3:K6 isolates
    Ashraf A Khan
    Division of Microbiology, US Food and Drug Administration, NCTR, Jefferson, AR 72079, USA
    FEMS Microbiol Lett 206:209-14. 2002
    ..and other closely related species and no amplification of the 327-bp PCR product was found. The PCR method can be used to specifically identify O3:K6 V. parahaemolyticus isolates in less than 6 h...
  2. pmc Molecular cloning, nucleotide sequence, and expression in Escherichia coli of a hemolytic toxin (aerolysin) gene from Aeromonas trota
    A A Khan
    Division of Microbiology, Food and Drug Administration, Jefferson, Arkansas 72079, USA
    Appl Environ Microbiol 64:2473-8. 1998
    ..trota exhibited 99% homology with the amino acid sequence of the aerA product of Aeromonas sobria AB3 and 57% homology with the amino acid sequences of the products of the aerA genes of Aeromonas salmonicida 17-2 and A. sobria 33...
  3. ncbi request reprint Classification of a polycyclic aromatic hydrocarbon-metabolizing bacterium, Mycobacterium sp. strain PYR-1, as Mycobacterium vanbaalenii sp. nov
    Ashraf A Khan
    Division of Microbiology, National Center for Toxicological Research, US Food and Drug Administration, 3900 NCTR Road, Jefferson, AR 72079, USA
    Int J Syst Evol Microbiol 52:1997-2002. 2002
    ..nov. is proposed...
  4. ncbi request reprint Identification of Aeromonas trota (hybridization group 13) by amplification of the aerolysin gene using polymerase chain reaction
    A A Khan
    National Center for Toxicological Research, Food and Drug Administration, Jefferson, AR 72079, USA
    Mol Cell Probes 13:93-8. 1999
    ..The method described here can be used to detect aerolysin-producing A. trota (hybridization group 13) strains from environmental and clinical samples without the use of selective media or additional biochemical tests...
  5. ncbi request reprint Identification of predominant human and animal anaerobic intestinal bacterial species by terminal restriction fragment patterns (TRFPs): a rapid, PCR-based method
    A A Khan
    Division of Microbiology, Food and Drug Administration, Jefferson, AR 72079, USA
    Mol Cell Probes 15:349-55. 2001
    ..This protocol is rapid, accurate, sensitive and capable of identifying multiple organisms in a single sample...
  6. ncbi request reprint Detection of multidrug-resistant Salmonella typhimurium DT104 by multiplex polymerase chain reaction
    A A Khan
    Division of Microbiology, Food and Drug Administration, National Center for Toxicological Research, Jefferson, AR 72079, USA
    FEMS Microbiol Lett 182:355-60. 2000
    ..This method will be useful for rapid identification of ACSSuT-type DT104 strains from clinical, food and environmental samples...
  7. doi request reprint Detection and characterization of virulence genes and integrons in Aeromonas veronii isolated from catfish
    Mohamed Nawaz
    Division of Microbiology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, AR 72079, USA
    Food Microbiol 27:327-31. 2010
    ..Our results indicate that farm-raised catfish may be a source of pathogenic A. veronii and that the potential health risks posed by virulent strains of A. veronii should not be underestimated...
  8. ncbi request reprint Novel organization of genes in a phthalate degradation operon of Mycobacterium vanbaalenii PYR-1
    Robin L Stingley
    Division of Microbiology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, AR 72079, USA
    Microbiology 150:3749-61. 2004
    ..In addition, the M. vanbaalenii PYR-1 pht operon contains no decarboxylase gene and none was identified within a 37 kb region containing the operon. This study is the first report of a phthalate degradation operon in Mycobacterium spp...
  9. ncbi request reprint Molecular characterization of cytochrome P450 genes in the polycyclic aromatic hydrocarbon degrading Mycobacterium vanbaalenii PYR-1
    Barbara Brezna
    Division of Microbiology, National Center for Toxicological Research, US Food and Drug Administration, 3900 NCTR Road, Jefferson, AR 72079, USA
    Appl Microbiol Biotechnol 71:522-32. 2006
    ..surveyed contain both monooxygenases and dioxygenases to degrade PAHs. Our results provide further evidence for the diverse enzymatic capability of Mycobacterium spp. to metabolize polycyclic aromatic hydrocarbons...
  10. ncbi request reprint Isolation and characterization of tetracycline-resistant Citrobacter spp. from catfish
    Mohamed Nawaz
    Division of Microbiology, National Center for Toxicological Research, Jefferson, AR 72079, USA
    Food Microbiol 25:85-91. 2008
    ..freundii, 3 distinct mrps among the 7 strains of C. braakii and 4 unique mrps among the 7 strains of C. amalonaticus. Our results indicate that citrobacters from catfish could serve as reservoirs of tetracycline-resistance determinants...
  11. doi request reprint Molecular characterization of tetracycline-resistant genes and integrons from avirulent strains of Escherichia coli isolated from catfish
    Mohamed Nawaz
    Division of Microbiology, National Center for Toxicological Research, Jefferson, Arkansas 72079, USA
    Foodborne Pathog Dis 6:553-9. 2009
    ..coli that could serve as a reservoir of tetracycline, trimethoprim, and aminoglycoside resistance genes...
  12. doi request reprint Isolation and molecular characterization of Salmonella enterica serovar Enteritidis from poultry house and clinical samples during 2010
    Ezat H Mezal
    Microbiology Division, National Center for Toxicological Research, U S Food and Drug Administration, Jefferson, AR 72079, USA University of Arkansas at Little Rock, Little Rock, AR 72205, USA University of Thi Qar, Science of College, Biology of Dept, Thi Qar, Iraq
    Food Microbiol 38:67-74. 2014
    ..Enteritidis in both poultry and clinical sources. However, the plasmid and MLVA allele profiles were a useful and important epidemiology tool to discriminate outbreak strains of ser. Enteritidis from poultry and clinical samples. ..
  13. pmc Identification and characterization of Class 1 integron resistance gene cassettes among Salmonella strains isolated from imported seafood
    Ashraf A Khan
    Division of Microbiology, U S Food and Drug Administration, National Center for Toxicological Research, Jefferson, AR 72079, USA
    Appl Environ Microbiol 75:1192-6. 2009
    ..Our study indicates that imported seafood could be a reservoir for Salmonella isolates resistant to multiple antibiotics...
  14. ncbi request reprint Molecular characterization of multidrug-resistant Enterococcus spp. from poultry and dairy farms: detection of virulence and vancomycin resistance gene markers by PCR
    Saeed A Khan
    Division of Microbiology, National Center for Toxicological Research FDA, 3900 NCTR Road, Jefferson, AR 72079, USA
    Mol Cell Probes 19:27-34. 2005
    ..None of the virulence factors were found in milk or poultry isolates. Intermediate level resistance to vancomycin in enterococci from the US animal farms was predominantly due to the presence of vanC1 gene...
  15. ncbi request reprint Identification and molecular characterization of Salmonella spp. from unpasteurized orange juices and identification of new serotype Salmonella strain S. enterica serovar Tempe
    Ashraf A Khan
    Microbiology Division, US Food and Drug Administration, National Center for Toxicological Research, Jefferson, Arkansas 72079, USA
    Food Microbiol 24:539-43. 2007
    ..The PFGE patterns were different for each S. enterica serotypes suggesting the several origins of contamination in outbreak. S. enterica serotype...
  16. doi request reprint Isolation and molecular characterization of Salmonella enterica serovar Javiana from food, environmental and clinical samples
    Ezat H Mezal
    Microbiology Division, National Center for Toxicological Research, U S Food and Drug Administration, Jefferson, AR 72079, USA
    Int J Food Microbiol 164:113-8. 2013
    ..This study provides data that support the potential transmission of S. Javiana virulence factors from food and environmental sources to cause infections in humans...
  17. doi request reprint Isolation and characterization of small qnrS1-carrying plasmids from imported seafood isolates of Salmonella enterica that are highly similar to plasmids of clinical isolates
    Tatsuya Akiyama
    Division of Microbiology, US Food and Drug Administration, National Center for Toxicological Research, Jefferson, AR 72079, USA
    FEMS Immunol Med Microbiol 64:429-32. 2012
    ..This is the first complete sequence of a qnrS1-carrying plasmid from imported seafood isolate of S. enterica...
  18. doi request reprint Molecular characterization of Salmonella enterica serovar Saintpaul isolated from imported seafood, pepper, environmental and clinical samples
    Tatsuya Akiyama
    Microbiology Division, US Food and Drug Administration, National Center for Toxicological Research, Jefferson, AR 72079, USA
    Food Microbiol 28:1124-8. 2011
    ..Our findings indicated the genetic diversity of S. Saintpaul in clinical samples, imported seafood, and the environment and that this serotype possesses several virulent genes and plasmids which can cause salmonellosis...
  19. doi request reprint The tetA gene decreases tigecycline sensitivity of Salmonella enterica isolates
    Tatsuya Akiyama
    Microbiology Division, National Center for Toxicological Research, U S Food and Drug Administration, Jefferson, AR 72079, USA
    Int J Antimicrob Agents 42:133-40. 2013
    ..This study indicates that the tetA gene decreases sensitivity to tigecycline in Salmonella spp. at a low level. With additional resistance mechanisms, tetA-carrying strains can reach the breakpoint for tigecycline resistance...
  20. pmc Biochemical and molecular characterization of tetracycline-resistant Aeromonas veronii isolates from catfish
    Mohamed Nawaz
    Division of Microbiology, National Center for Toxicological Research, Food and Drug Administration, Jefferson, AR 72079, USA
    Appl Environ Microbiol 72:6461-6. 2006
    ..Our results indicate the need for use of 16S rRNA in the identification of Aeromonas spp. and the prevalence of catfish as a reservoir of tet genes...
  21. doi request reprint Molecular characterization of strains of fluoroquinolone-resistant Salmonella enterica serovar Schwarzengrund carrying multidrug resistance isolated from imported foods
    Tatsuya Akiyama
    Microbiology Division, US Food and Drug Administration, National Center for Toxicological Research, Jefferson, AR 72079, USA
    J Antimicrob Chemother 67:101-10. 2012
    ..To determine the fluoroquinolone resistance determinants in Salmonella enterica serovar Schwarzengrund from imported foods...
  22. ncbi request reprint Molecular characterization of dioxygenases from polycyclic aromatic hydrocarbon-degrading Mycobacterium spp
    Barbara Brezna
    Division of Microbiology, National Center for Toxicological Research, U S Food and Drug Administration, Jefferson, AR 72079, USA
    FEMS Microbiol Lett 223:177-83. 2003
    ..However, only one copy of each gene was observed in PAH2.135...
  23. ncbi request reprint Detection of galE gene by polymerase chain reaction in campylobacters associated with Guillain-Barre syndrome
    Mohamed S Nawaz
    Department of Microbiology, Food and Drug Administration, The National Center for Toxicological Research, Jefferson AR 72079, Argentina
    Mol Cell Probes 17:313-7. 2003
    ..E. coli and Salmonella spp. The entire diagnostic assay, including template preparation, amplification and electrophoresis, can be completed within 6 h...
  24. ncbi request reprint Isolation and molecular characterization of fluoroquinolone-resistant Escherichia coli from poultry litter
    A A Khan
    US Food and Drug Administration, National Center for Toxicological Research, Jefferson, Arkansas 72079, USA
    Poult Sci 84:61-6. 2005
    ..Fluoroquinolone resistance was present among different serotypes and ribotypes, and drug resistance profiles suggest that the incidence of resistance does not indicate a clonal population in avian E. coli...
  25. ncbi request reprint Identification and sequencing of a cDNA encoding 6-phosphogluconate dehydrogenase from a fungus, Cunninghamella elegans and expression of the gene in Escherichia coli
    R F Wang
    Microbiology Division, National Center for Toxicological, Research, FDA, Jefferson, AR 72079 9502, USA
    FEMS Microbiol Lett 169:397-402. 1998
    ..Bacterial 6-phosphogluconate dehydrogenase and higher organisms' 6-phosphogluconate dehydrogenase were found in different clusters...
  26. ncbi request reprint Isolation and characterization of Enterobacter cloacae capable of metabolizing asparagine
    M S Nawaz
    Division of Microbiology, National Center for Toxicological Research, Jefferson, AR 72079, USA
    Appl Microbiol Biotechnol 50:568-72. 1998
    ..The pH and temperature optimum of L-asparaginase was 8.5 and 37-42 degrees C, respectively. The half-life of the enzyme at 30 degrees C and 37 degrees C was 10 and 8 h, respectively...
  27. ncbi request reprint Biochemical and molecular characterization of erthromycin-resistant avian Staphylococcus spp. isolated from chickens
    M S Nawaz
    Division of Microbiology, National Center for Toxicological Research, Food and Drug Administration, Jefferson, Arkansas 72079, USA
    Poult Sci 78:1191-7. 1999
    ..and that ermA was the predominant gene in coagulase-negative and coagulase-positive avian Staphylococcus spp. The size and copy numbers of the ermA gene were different from its human counterpart...
  28. ncbi request reprint Cloning, sequencing, and expression in Escherichia coli of a cytochrome P450 gene from Cunninghamella elegans
    R F Wang
    Division of Microbiology, National Center for Toxicological Research, FDA, Jefferson, AR 72079 9502, USA
    FEMS Microbiol Lett 188:55-61. 2000
    ..elegans sequence. The C. elegans P450 clustered close to the cyp51 family and was named cyp509A1 by the International Committee on the Nomenclature for Cytochrome P450 Enzymes...
  29. ncbi request reprint Comparative molecular analysis of erythromycin-resistance determinants in staphylococcal isolates of poultry and human origin
    M S Nawaz
    Division of Microbiology, National Center for Toxicological Research FDA, 3900 NCTR Road, Jefferson, AR 72079, USA
    Mol Cell Probes 14:311-9. 2000
    ..0, 21.0, 10.5, 6.2 and 4. 8 kb) for the clinical strains and two (8.0 and 6.2 kb) for the poultry strains. The 6.2 kb RFLP pattern, in both the poultry and human clinical isolates, indicates a common lineage for the ermA gene...
  30. ncbi request reprint Molecular characterization of fluoroquinolone-resistant Campylobacter spp. isolated from poultry
    M S Nawaz
    Division of Microbiology, National Center for Toxicological Research, Food and Drug Administration, Jefferson, Arkansas 72079, USA
    Poult Sci 82:251-8. 2003
    ..The PFGE patterns of the 17 fluoroquinolone-resistant isolates were different from the nine sensitive campylobacter strains...
  31. ncbi request reprint Molecular characterization of a phenanthrene degradation pathway in Mycobacterium vanbaalenii PYR-1
    Robin L Stingley
    National Center for Toxicological Research, US FDA, 3900 NCTR Road, Jefferson, AR 72079, USA
    Biochem Biophys Res Commun 322:133-46. 2004
    ..This study is the first to identify genes responsible for the degradation of phenanthrene via the phthalic acid pathway in Mycobacterium species...
  32. ncbi request reprint Rapid phenotypic characterization of Vibrio isolates by pyrolysis metastable atom bombardment mass spectrometry
    Jon G Wilkes
    Divisions of Systems Toxicology, Microbiology or Biochemical Toxicology, National Center for Toxicological Research, FDA, 3900 NCTR Drive, Jefferson, AR 72079, USA
    Antonie Van Leeuwenhoek 88:151-61. 2005
    ..This integrated analytical, pattern-recognition system should be examined further for potential utility in clinical and public health diagnostic contexts...
  33. doi request reprint Isolation and Characterization of Antimicrobial-Resistant Nontyphoidal Salmonella enterica Serovars from Imported Food Products
    Dongryeoul Bae
    U S Food and Drug Administration, National Center for Toxicological Research, Division of Microbiology, Jefferson, Arkansas 72079, USA
    J Food Prot 79:1348-54. 2016
    ....
  34. doi request reprint Characterization of extended-spectrum β-lactamase (ESBL) producing non-typhoidal Salmonella (NTS) from imported food products
    Dongryeoul Bae
    Division of Microbiology, National Center for Toxicological Research, U S Food and Drug Administration, Jefferson, AR 72079, United States
    Int J Food Microbiol 214:12-7. 2015
    ..The contamination of imported food products by NTS with conjugative plasmid-borne ESBL genes may contribute to the spread of ESBL-producing NTS and compromise the therapeutic activity of extended-spectrum β-lactam antibiotics...
  35. ncbi request reprint Detection and characterization of erythromycin-resistant methylase genes in Gram-positive bacteria isolated from poultry litter
    A A Khan
    Division of Microbiology, National Center for Toxicological Research, Food and Drug Administration, Jefferson, AR 72079, USA
    Appl Microbiol Biotechnol 59:377-81. 2002
    ....
  36. pmc Molecular cloning, nucleotide sequence, and expression of genes encoding a polycyclic aromatic ring dioxygenase from Mycobacterium sp. strain PYR-1
    A A Khan
    Division of Microbiology, National Center for Toxicological Research, Food and Drug Administration, Jefferson, Arkansas 72079, USA
    Appl Environ Microbiol 67:3577-85. 2001
    ..The functionality of the genes for PAH degradation was confirmed in a phagemid clone containing all three genes, as well as in plasmid subclones containing the two genes encoding the dioxygenase subunits...
  37. doi request reprint Detection and functionality of the CdtB, PltA, and PltB from Salmonella enterica serovar Javiana
    Ezat H Mezal
    Division of Microbiology, National Center for Toxicological Research, U S Food and Drug Administration, Jefferson, AR, USA University of Arkansas at Little Rock, Little Rock, AR, USA University of Thi Qar, Thi Qar, Iraq
    Pathog Dis 72:95-103. 2014
    ..Our data show a significant difference between the wild-type cdtB strain and its isogenic ∆cdtB for invasion of the cell lines. Therefore, CdtB produced from S. Javiana strains may play an important role in pathogenesis in host cells...
  38. ncbi request reprint A simple and efficient Triton X-100 boiling and chloroform extraction method of RNA isolation from Gram-positive and Gram-negative bacteria
    Kidon Sung
    US Food and Drug Administration, National Center for Toxicological Research, Division of Microbiology, 3900 NCTR Road, Jefferson, AR 72079, USA
    FEMS Microbiol Lett 229:97-101. 2003
    ..The method provides a rapid, reliable, and simple tool for the isolation of good quality RNA suitable for various molecular biology experiments...
  39. ncbi request reprint DNA packaging and developmental intermediates of a broad host range Vibrio vulnificus bacteriophage 71A-6
    S A Khan
    Division of Microbiology, National Center for Toxicological Research, Food and Drug Administration, 3900 NCTR Road, Jefferson, AR 72079, USA
    Mol Cell Probes 15:61-9. 2001
    ..The size of the bacteriophage 71A-6 genome was determined to be 143.0-kb by pulsed-field gel electrophoresis. The total mass of all the mature phage proteins corresponded to only 14.0% of the coding capacity of phage genome...
  40. ncbi request reprint Prevalence and characterization of Salmonella enterica serovar Weltevreden from imported seafood
    Elizabeth Ponce
    Departamento de Biotecnología Marina, Km 107 Carretera Tijuana Ensenada, Ensenada, B C 22860, Mexico
    Food Microbiol 25:29-35. 2008
    ..Our findings show genetic diversity and temporal persistence of S. enterica serovar Weltevreden in recently monitored seafood imports...
  41. ncbi request reprint Occurrence of non-O157 shiga toxin-producing Escherichia coli in ready-to-eat food from supermarkets in Argentina
    Claudia Balagué
    Faculty of Biochemical and Pharmaceutical Sciences, National University of Rosario, Argentina
    Food Microbiol 23:307-13. 2006
    ..These strains are potential foodborne pathogens and their presence in ready-to-eat food illustrates the need to keep a careful watch for the source of pathogens and then develop methods to control them...
  42. ncbi request reprint Characterization of class 1 integron resistance gene cassettes in Salmonella enterica serovars Oslo and Bareily from imported seafood
    Ashraf A Khan
    J Antimicrob Chemother 58:1308-10. 2006