1,721,009 research outputs found
Capsule production in Escherichia coli: co-ordinate regulation of biosynthesis and export by environmental factors
No full textValidation of a seminested PCR approach for rapid detection of Salmonella enterica subsp. enterica serovar Gallinarum
No full textSalmonella enterica subsp. enterica serovar Gallinarum (S. Gallinarum) is the causative agent of fowl typhoid,
one of the major causes of mortality and morbidity on poultry farms. Even though it has been substantially
eradicated in many developed countries, the disease still remains endemic in Central and South America, in
Africa and in the Mediterranean countries of Europe. This leads to the routine screening of flocks, mainly by
cultivation and serological techniques, which are expensive, as well as time and labour-consuming. Here we
describe a simple and specific PCR-based method for detecting S. Gallinarum. It relies on two seminested PCRs
which use four pairs of primers designed on the basis of two genomic regions which appear to be exclusive to
the pathogen. Furthermore, an internal positive control was devised in order to avoid any false negative
results. We performed sensitivity and specificity tests, and our findings showed the cogency of the system and
its potential effectiveness even for routine uses
Molecular characterization and antimicrobial susceptibility of Salmonella enteritidis and S. typhimurium isolated from laying hens in Southern Italy
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SXT-related integrating conjugative element and IncC plasmids in Vibrio cholerae O1 strains in Eastern Africa
No full textObjectives: The objective of this study was to investigate the extent of resistance patterns and associated
mobile genetic elements in epidemic V. cholerae O1 El Tor strains isolated from Eastern Africa in
the late 1990s.
Methods: Self-transmissible genetic elements and associated clusters of genes encoding resistance
were detected by conjugation experiments. Detection of SXT-related integrating conjugative elements
(ICEs) and associated antibiotic resistance genes was performed by PCR to amplify the SXT elementintegrase
gene (int), right SXT element-chromosome junction (attP-prfC) and genes conferring resistance
to chloramphenicol (floR), sulfamethoxazole (sulII), streptomycin (strA) and trimethoprim (dfrA1).
Genomic relatedness was established by random amplified polymorphic DNA patterns.
Results: Of 224 strains analysed, 200 isolates exhibited resistance to four or more antimicrobials. An
IncC plasmid, encoding resistance to ampicillin, chloramphenicol, streptomycin, sulfamethoxazole and
trimethoprim, conferred multidrug resistance to 113 strains isolated from Somalia and Ethiopia, whereas
an SXT-related ICE, encoding resistance to chloramphenicol, streptomycin, sulfamethoxazole and
trimethoprim, conferred multidrug resistance to 74 strains isolated from Sudan, Kenya and Tanzania.
Conclusions: This study has shown the spread of SXT-related ICEs among V. cholerae O1 African isolates.
It has also highlighted the role of two distinct genetic elements in conferring multiple resistance to
the two distinct groups of V. cholerae O1 strains that, in the late 1990s, spread through Eastern Africa, a
critical geographic region for the persistence and transmission of cholera to the entire continent
Susceptibility to rifaximin of Vibrio cholerae strains from different geographical areas
No full textFour hundred and eight clinical strains of Vibrio cholerae isolated from different geographical areas and with different antimicrobial resistance patterns were tested for susceptibility to rifaximin, a non-absorbable antibiotic active in vitro against Gram-negative bacteria. The MICs ranged from 0.5 to 4 mg/l for all strains. These values and the pharmacokinetic properties suggest rifaximin as an attractive antimicrobial agent for choler
Activity of CMP-2-keto-3-deoxyoctulonic acid synthetase in Escherichia coli strains expressing the capsular K5 polysaccharide implication for K5 polysaccharide biosynthesis
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Molecular epidemiology and origin of cholera reemergence in Italy and Albania in the 1990s
No full textIn 1994 a cholera epidemic occurred in Italy and Albania after more than a decade of case absence. To investigate genotypic characteristics and
the origin of the epidemic strains, 110 Vibrio cholerae O1 El Tor isolates from Italy and Albania were studied by randomly amplified polymorphic
DNA analysis (RAPD), BglI ribotyping, and pulsed-field gel electrophoresis (PFGE) of genomic DNA. The Italian and Albanian strains were all
ribotype 6 and their RAPD and PFGE patterns were identical as well. These findings indicated that the 1994 isolates belonged to the same clone
and that the clone was part of the larger global spread of epidemic ribotype 6 strains, which started in southern Asia in 1990
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