Evolution of trimethoprim/sulfamethoxazole resistance in Shewanella algae from the perspective of comparative genomics and global phylogenic analysis.

OBJECTIVE: Shewanella algae is a zoonotic marine bacterium that causes a variety of infections in immunocompromised patients or those who have been exposed to seawater. The development of trimethoprim/sulfamethoxazole (TMP/SMX) resistance in S. algae are found in human and environment isolates during the past ten years, and thus the treatment options are decreasing. METHODOLOGY: In the study, we conduct a comparative genomic study to identify the resistant mechanism of TMP/SMX-resistance in S. algae. RESULTS: We found the resistance of TMP/SMX in S. algae is associated with the existence of sul1 and dfrA12 within the class 1 integron. The gene cassette dfra12-aadA2-qacEΔ1/sul1 within the class 1 integron is highly conserved. In addition, the class 1 integron and encapsulated sul1 are significantly enriched in Enterobacteriaceae in NCBI and UniProt databases. CONCLUSION: Our study suggests that the horizontal transfer of TMP/SMX resistance via class 1 integron is most frequently occurred within Enterobacteriaceae and has spread to a wide range of sources including soil, poultry, and marine water.

Genome Sequence of Colistin-Resistant Bacteremic Shewanella algae Carrying the Beta-Lactamase Gene bla OXA-55.

Shewanella algae is an emerging pathogen widely distributed in aquatic environment. Bacteremia is a major manifestation of S. algae infections, and there are increasing reports of antibiotic-resistant strains. However, little is known about the genomic characteristics of human bacteremic S. algae. Here, we report the results of the whole-genome sequencing of colistin-resistant S. algae TYL, a blood isolate. Chromosome-encoded pmrC associated with colistin resistance and bla OXA-55 gene intrinsic to S. algae was identified. Continuous surveillance for the emergence of S. algae is needed.

Genomic and phylogenetic characterization of Shewanella xiamenensis isolated from giant grouper (Epinephelus lanceolatus) in Taiwan.

Shewanella xiamenensis is an emerging pathogen causing intra-abdominal infection and intestinal colonization. Epidemiologic clues suggest its role as a potential food-borne zoonotic agent. To date, four genome sequences of S. xiamenensis have been made publicly available. All of them were isolated from water samples. In this study, we characterized the genome of a S. xiamenensis strain isolated from a giant grouper in Taiwan. The genome of S. xiamenensis ZYW1 is 4,827,717 bp in length and encodes 4,239 open reading frames. Its genomic sequence shares high homology with other S. xiamenensis strains. blaOXA-416 was identified. This is the first detection of S. xiamenensis in Taiwan. These genomic data and analyses contribute to our understanding of S. xiamenensis and may help to elucidate disease-causing mechanisms in future studies.

Whole-genome characterization of Shewanella algae strain SYT3 isolated from seawater reveals insight into hemolysis.

AIM: To describe the genomic characteristics of seawater-borne hemolytic Shewanella algae and its resistance genes. MATERIALS & METHODS: Whole genome sequence of S. algae SYT3 was determined using llumina MiSeq platform. Multiple-database-based analysis was performed to identify the genetic background of its hemolytic activity and the antibiotic resistance genes. RESULTS: S. algae SYT3 possesses a homolog of the hly operon involved in the synthesis of hemolysin. We also identified candidate genes associated with resistance to ß-lactam antibiotics (bla OXA-55) and fluoroquinolone (qnrA3). CONCLUSION: The study provides an insight into the hemolytic activity of S. algae. Our findings also suggested S. algae as a potential reservoir of antimicrobial resistance determinants.

Genome characterization of bile-isolated Shewanella algae ACCC.

BACKGROUND: Shewanella algae has been recognized as an emerging human pathogen. However, not much is known about the mechanism of its pathogenesis and its adaptation to a special niche such as the hepatobiliary tract. RESULTS: In this study, we isolated the S. algae ACCC strain from human bile and performed whole genome sequencing. S. algae ACCC consists of a circular 4,743,354-bp chromosome with a GC content of 53.08%, within 4080 protein coding sequences. The genome of strain ACCC contains a number of candidate genes which have been reported to be associated with bile adaption, including htpB, exbBD, wecA, galU, adeFGH and phoPQ regulon. CONCLUSIONS: Our results highlight the association of S. algae with a rare disease profile. Further studies are needed to shed light on the evolution of pathogenesis and the niche adaptation of S. algae.

Draft genome sequence of carbapenem-resistant Shewanella algae strain AC isolated from small abalone (Haliotis diversicolor).

OBJECTIVES: Shewanella algae is an environmental marine bacterium and an emerging opportunistic human pathogen. Moreover, there are increasing reports of strains showing multidrug resistance, particularly carbapenem-resistant isolates. Although S. algae has been found in bivalve shellfish aquaculture, there is very little genome-wide data on resistance determinants in S. algae from shellfish. The aim of this study was to determine the whole genome sequence of carbapenem-resistant S. algae strain AC isolated from small abalone in Taiwan. METHODS: Bacterial genomic DNA was sequenced using an Illumina MiSeq platform with 250-bp paired-end reads. De novo genome assembly was performed using Velvet v.1.2.07. The whole genome was annotated and several candidate genes for antimicrobial resistance were identified. RESULTS: The genome size was calculated at 4751156bp, with a mean G+C content of 53.09%. A total of 4164 protein-coding sequences, 7 rRNAs, 85 tRNAs and 5 non-coding RNAs were identified. The genome contains genes associated with resistance to ß-lactams, trimethoprim, tetracycline, colistin and quinolones. Multiple efflux pump genes were also detected. CONCLUSION: Small abalone is a potential source of foodborne drug-resistant S. algae. The genome sequence of carbapenem-resistant S. algae strain AC isolated from small abalone will provide valuable information for further study of the dissemination of resistance genes at the human-animal interface.