Emergence and Prevalence of Non-H ₂ S-Producing Salmonella enterica Serovar Senftenberg Isolates Belonging to Novel Sequence Type 1751 in China

Abstract

g Salmonella enterica serovar Senftenberg is a common nontyphoidal Salmonella serotype which causes human Salmonella infections worldwide. In this study, 182 S. Senftenberg isolates, including 17 atypical non-hydrogen sulfide (H 2 S)-producing isolates, were detected in China from 2005 to 2011. The microbiological and genetic characteristics of the non-H 2 S-producing and selected H 2 S-producing isolates were determined by using pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and clustered regularly interspaced short palindromic repeat (CRISPR) analysis. The phs operons were amplified and sequenced. The 17 non-H 2 S-producing and 36 H 2 S-producing isolates belonged to 7 sequence types (STs), including 3 new STs, ST1751, ST1757, and ST1758. Fourteen of the 17 non-H 2 S-producing isolates belonged to ST1751 and had very similar PFGE patterns. All 17 non-H 2 S-producing isolates had a nonsense mutation at position 1621 of phsA. H 2 S-producing and non-H 2 Sproducing S. Senftenberg isolates were isolated from the same stool sample from three patients; isolates from the same patients displayed the same antimicrobial susceptibility, ST, and PFGE pattern but could be discriminated based on CRISPR spacers. Non-H 2 S-producing S. Senftenberg isolates belonging to ST1751 have been prevalent in Shanghai, China. It is possible that these emerging organisms will disseminate further, because they are difficult to detect. Thus, we should strengthen the surveillance for the spread of this atypical S. Senftenberg variant.

Genomic and Phenotypic Analyses Reveal the Emergence of an Atypical Salmonella enterica Serovar Senftenberg Variant in China

“…The atypical SC1 isolates, assigned to eBG30, comprise three distinct STs, with ST1751 having been reported only from China and being associated with recent outbreaks (26). Interestingly, the majority of Salmonella Senftenberg ST1751 isolates are non-H 2 S producers.…”

“…Interestingly, the majority of Salmonella Senftenberg ST1751 isolates are non-H 2 S producers. However, both H 2 S producer and nonproducer strains have previously been isolated from the same patient (26). There is some evidence supporting the possibility that non-H 2 S-producing Salmonella isolates might have an increased ability to survive in the host intestine (44).…”

“…Moreover, illnesses caused by metallo-␤-lactamase-producing S. Senftenberg that are associated with international travel have been identified recently in the United States (25). In addition, atypical S. Senftenberg isolates that lack the ability to produce hydrogen sulfide (H 2 S) have been identified in China (26). Thus, antimicrobial-resistant isolates of S. Senftenberg are emerging globally, and this, coupled with the persistence of S. Senftenberg in animals reared for food production and with an atypical biochemical signature, has potentially far-reaching public health implications.…”

Antimicrobial Resistance and Molecular Investigation of H2S-Negative Salmonella enterica subsp. enterica serovar Choleraesuis Isolates in China

“…We previously reported 17 H 2 S-negative S . Senftenberg isolates worldwide with a nonsense mutation at position 1621 of the phsA gene [ 15 ]. Here, we identified 19 H 2 S-negative isolates among 21 S .…”

“…Choleraesuis was extracted using a TIANamp Bacteria DNA Kit (Tiangen Biotech, Beijing, China) according to the manufacturer’s directions. The primers and PCR conditions used were the same as previously described [ 15 ]. The PCR products were sequenced and the DNA sequences were imported into DNAStar version 7.1.0 (Lasergene, Madison, WI, USA) for analysis.…”