title: The genome sequence of Salmonella enterica serovar Choleraesuis, a highly invasive and resistant zoonotic pathogen.
abstract: Salmonella enterica serovar Choleraesuis (S. Choleraesuis), a highly invasive serovar among non-typhoidal Salmonella, usually causes sepsis or extra-intestinal focal infections in humans. S. Choleraesuis infections have now become particularly difficult to treat because of the emergence of resistance to multiple antimicrobial agents. The 4.7 Mb genome sequence of a multidrug-resistant S. Choleraesuis strain SC-B67 was determined. Genome wide comparison of three sequenced Salmonella genomes revealed that more deletion events occurred in S. Choleraesuis SC-B67 and S.Typhi CT18 relative to S. Typhimurium LT2. S. Choleraesuis has 151 pseudogenes, which, among the three Salmonella genomes, include the highest percentage of pseudogenes arising from the genes involved in bacterial chemotaxis signal-transduction pathways. Mutations in these genes may increase smooth swimming of the bacteria, potentially allowing more effective interactions with and invasion of host cells to occur. A key regulatory gene of TetR/AcrR family, acrR, was inactivated through the introduction of an internal stop codon resulting in overexpression of AcrAB that appears to be associated with ciprofloxacin resistance. While lateral gene transfer providing basic functions to allow niche expansion in the host and environment is maintained during the evolution of different serovars of Salmonella, genes providing little overall selective benefit may be lost rapidly. Our findings suggest that the formation of pseudogenes may provide a simple evolutionary pathway that complements gene acquisition to enhance virulence and antimicrobial resistance in S. Choleraesuis.
authors.affiliation: Department of Pediatrics, Chang Gung Children's Hospital Taoyuan, Taiwan. chchiu@adm.cgmh.org.tw
authors.forename: Cheng-Hsun
authors.initials: CH
authors.lastname: Chiu
authors.forename: Petrus
authors.initials: P
authors.lastname: Tang
authors.forename: Chishih
authors.initials: C
authors.lastname: Chu
authors.forename: Songnian
authors.initials: S
authors.lastname: Hu
authors.forename: Qiyu
authors.initials: Q
authors.lastname: Bao
authors.forename: Jun
authors.initials: J
authors.lastname: Yu
authors.forename: Yun-Ying
authors.initials: YY
authors.lastname: Chou
authors.forename: Hsin-Shih
authors.initials: HS
authors.lastname: Wang
authors.forename: Ying-Shiung
authors.initials: YS
authors.lastname: Lee
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry; D001483:Base Sequence; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D016680:Genome, Bacterial; D006801:Humans; D010957:Plasmids / Q000235:genetics; D011544:Pseudogenes; D012475:Salmonella / Q000235:genetics; D012480:Salmonella Infections / Q000382:microbiology; D019779:Salmonella enterica / Q000235:genetics* / Q000472:pathogenicity; D017386:Sequence Homology, Amino Acid; D015047:Zoonoses / Q000382:microbiology; D014841:von Willebrand Factor / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D014841:von Willebrand Factor