Molecular Characterization of Salmonella enterica Serovar Aberdeen Negative for H2S Production in China

Abstract

Salmonella enterica infections continue to be a significant burden on public health worldwide. The ability of S. enterica to produce hydrogen sulfide (H2S) is an important phenotypic characteristic used to screen and identify Salmonella with selective medium; however, H2S-negative Salmonella have recently emerged. In this study, the H2S phenotype of Salmonella isolates was confirmed, and the selected isolates were subjected to antimicrobial susceptibility testing and molecular identification by multilocus sequence typing, pulsed-field gel electrophoresis, and clustered regularly interspaced short palindromic repeat (CRISPR) analysis. The phs genetic operon was also analyzed. A total of 160 S. enterica serovar Aberdeen isolates were detected between 2005 and 2013 in China. Of them, seven non-H2S-producing isolates were detected. Notably, four samples yielded four pairs of isolates with different H2S phenotypes, simultaneously. The data demonstrated that H2S-negative isolates were genetically closely related to H2S-positive isolates. Three new spacers (Abe1, Abe2, and Abe3) were identified in CRISPR locus 1 in four pairs of isolates with different H2S phenotypes from the same samples. Sequence analysis revealed a new nonsense mutation at position 208 in the phsA gene of all non-H2S-producing isolates. Additionally, we describe a new screening procedure to avoid H2S-negative Salmonella, which would normally be overlooked during laboratory and hospital screening. The prevalence of this pathogen may be underestimated; therefore, it is important to focus on improving surveillance of this organism to control its spread.

Antibiotic resistance and molecular characterization of the hydrogen sulfide-negative phenotype among diverse Salmonella serovars in China

“…However, the phs operon is essential for this activity in Salmonella [ 24 ]. Sakano et al [ 8 ] detected a nonsense mutation in the phsA gene in H 2 S-negative S. Infantis and S. Typhimurium isolates, and in our previous studies, we found more mutations in the phsA gene of H 2 S-negative S. Senftenberg, S. Choleraesuis, and S. Aberdeen [ 13 – 15 ]. These data suggest that the disruption of the phs locus is responsible for the lack of H 2 S production and incorrect identification of Salmonella .…”

“…Previous studies have reported mutations in the phs operon may responsible for the non-H 2 S-producing phenotype in Salmonella [ 8 , 13 – 15 ] . In the phsA gene, three different mutation sites were detected among the 46 H 2 S-negative Salmonella isolates (Table 3 ).…”

“…However, H 2 S-negative Salmonella isolates have been continuously reported in different countries; thus, one isolate was identified in Kuwait, 10 in United States, 31 in Japan, and 58 in Southeast China [ 6 – 12 ]. In our previous studies, we also identified 43 H 2 S-negative Salmonella isolates during national surveillance of salmonellosis in China [ 13 – 15 ]. These results suggest that the occurrence of the atypical H 2 S-negative Salmonella variants is growing throughout the world.…”

Detection and characterization of multidrug‐resistant Salmonella enterica serovar Infantis as an emerging threat in poultry farms of Faisalabad, Pakistan

“…Salmonellosis due to this serovar has mostly affected children but it has also caused disease in adults (Ghoddusi et al 2015). More than 2700 serotypes of Salmonella have been reported (Wu et al 2016). Studies have shown S. Infantis as predominantly present in the poultry industry worldwide (Fuche et al 2016) and cause substantial economic losses (Rajagopal and Mini 2013).…”

H2S mediates interbacterial communication through the air reverting intrinsic antibiotic resistance

“…However, this has not been demonstrated for the S . Typhimurium specific PHS pathway, even though this is considered the main source of H 2 S in this species [23,24]. Therefore, we carried out various antimicrobial susceptibility tests (S1 Fig, Error!…”