Dataset Information

Salmonella enterica subsp. diarizonae Harboring ST233, ST1263, and ST1845 in Children.

ABSTRACT:

Objective

This study aims to analyze the molecular epidemiology, resistance, and pathogenicity of Salmonella enterica subsp. diarizonae isolated from children.

Methods

Whole genome sequencing was carried out, and molecular serotypes, sequence types, resistance genes, and virulence genes of S. enterica subsp. diarizonae isolates were analyzed. Antimicrobial susceptibility test was determined by commercialized microdilution method.

Results

A total of three isolates of S. enterica subsp. diarizonae were isolated during 2015 to 2020. The molecular serotypes of the three strains were 61:c:z35, 61:l,v:1,5,7:[z57], and 65:k:z, respectively, and the sequence types were ST1845, ST233, and ST1263. All the three isolates were susceptible to ceftriaxone, ceftazidime, cefepime, amoxycillin/clavulanic acid, piperacillin/tazobactam, ertapenem, imipenem, levofloxacin, and trimethoprim/sulfamethoxazole. No other resistant gene was detected except aac(6')-Iaa. There were no resistant plasmids detected in all the three isolates. A total of 76 genes were present in all isolates, containing 49 genes of Type III Secretion System (T3SS) mediated by SPI-1and SPI-2, 13 genes of adherence (type 1 fimbriae, Agf, and MisL-related genes), 11 genes of iron uptake (Yersiniabactin), two genes of magnesium uptake, and one gene of typhoid toxin(cdtB).

Conclusion

The serotypes and sequence types of S. enterica subsp. diarizonae isolates were rarely reported in children; all the S. enterica subsp. diarizonae isolates were susceptible to detected antibiotics; T3SS, adherence, iron uptake, magnesium uptake, and typhoid toxin were responsible for pathogenicity of the S. enterica subsp. diarizonae isolates in children.

SUBMITTER: Zhou M

PROVIDER: S-EPMC8417408 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundSalmonella enterica subsp. diarizonae (IIIb) is frequently isolated from the environment, cold-blooded reptiles, sheep and humans; however only a few studies describe the isolation of this subspecies from invasive human infections. The factors contributing to this unusual behavior are currently unknown.ResultsWe report here the genome features of two diarizonae strains, SBO13 and SBO27, isolated from endocervical tissue collected post-abortion and from cerebrospinal fluid of a newborn child, respectively, in the city of Santa Cruz, Bolivia. Although isolated six years apart, SBO27 in 2008 and SBO13 in 2014, both strains belong to the same sequence type 1256 (ST1256) and show a high degree of genome conservation sharing more than 99% of their genes, including the conservation of a ~ 10 kb plasmid. A prominent feature of the two genomes is the presence of 24 genomic islands (GIs), in addition to 10 complete Salmonella pathogenicity islands (SPI) and fragments of SPI-7, a pathogenicity island first reported in the human-adapted serovar Typhi. Some of the GIs identified in SBO13 and SBO27 harbor genes putatively encoding auto-transporters involved in adhesion, lipopolysaccharide modifying enzymes, putative toxins, pili-related proteins, efflux pumps, and several putative membrane cation transport related-genes, among others. These two Bolivian isolates also share genes encoding the type-III secretion system effector proteins SseK2, SseK3 and SlrP with other diarizonae sequence types (ST) mainly-associated with infections in humans. The sseK2, sseK3 and slrP genes were either absent or showing frameshift mutations in a significant proportion of genomes from environmental diarizonae isolates.ConclusionsThe comparative genomic study of two diarizonae strains isolated in Bolivia from human patients uncovered the presence of many genes putatively related to virulence. The statistically-significant acquisition of a unique combination of these functions by diarizonae strains isolated from humans may have impacted the ability of these isolates to successfully infect the human host.