Draft genome sequence of bla TEM-1 -mediated cephalosporin-resistant Salmonella enterica serovar Typhi from bloodstream infection
Enteric fever is a major cause of concern in developing countries across the globe. The primary choice of antibiotics remains fluoroquinolones, followed by cephalosporins. Resistance to third-generation cephalosporins is rarely reported in Salmonella enterica serovar Typhi. This study reports the wh...
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Veröffentlicht in: | Journal of global antimicrobial resistance. 2016-12, Vol.7, p.11 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Enteric fever is a major cause of concern in developing countries across the globe. The primary choice of antibiotics remains fluoroquinolones, followed by cephalosporins. Resistance to third-generation cephalosporins is rarely reported in Salmonella enterica serovar Typhi. This study reports the whole genome sequence of an S. Typhi isolate resistant to cefixime [minimum inhibitory concentration (MIC)=512μg/mL] by microbroth dilution. Interestingly, the isolate was negative for the cephalosporin resistance gene bla
by PCR, which is a known mechanism for higher cephalosporin resistance. The isolate was further subjected to next-generation sequencing that identified bla
and bla
genes in association with qnrB4 and sul1. bla
is a known gene coding for β-lactam resistance. In certain cases, overexpression of bla
was reported to result in cephalosporin resistance. This suggests that the high cefixime MIC would have been contributed by overexpression of bla
. The bla
gene was found to be associated with a promoter Px with -35 and -10 regions as TTAATA and TAAAGT, respectively. The promoter regions were unique, but the -10 region was similar to that found in Pa/Pb (previously reported promoter for bla
) with a single nucleotide change. In addition, an IncN plasmid was identified, which is usually reported in association with the most prevalent extended-spectrum β-lactamase (ESBL), metallo- and non-metallo-carbapenemase, and plasmid-mediated quinolone resistance (PMQR) genes. Plasmids such as IncN might possibly confer resistance and enhance spread. It is imperative to continuously monitor the drug resistance profile and evolving genetic elements. |
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ISSN: | 2213-7173 |