Genome analysis of Salmonella strains isolated from imported frozen fish in Burkina Faso

Authors: KAGAMBEGA, ASSETA - Institute Of Science; Frye, Jonathan; BELEM, SALIFOU - Joseph Ki-Zerbo University; McMillan, Elizabeth; Hiott, Lari; SHARMA, POONAM - Orise Fellow; GUPTA, SUSHIM - Orise Fellow; RAMADAN, HAZEM - Mansoura University; SORO, DANIEL - Joseph Ki-Zerbo University; BARRO, NICOLAS - Joseph Ki-Zerbo University; Jackson, Charlene

Submitted to: Annals of Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/16/2021
Publication Date: 7/31/2021
Citation: Kagambega, A., Frye, J.G., Belem, S., Mcmillan, E.A., Hiott, L.M., Sharma, P., Gupta, S., Ramadan, H., Soro, D., Barro, N., Jackson, C.R. 2021. Genome analysis of Salmonella strains isolated from imported frozen fish in Burkina Faso. Annals of Microbiology. 71:32. https://doi.org/10.1186/s13213-021-01642-8.
DOI: https://doi.org/10.1186/s13213-021-01642-8

Interpretive Summary: Improperly handled fish can expose consumers to pathogenic bacteria. The aim of this study was to isolate and characterize the genetics of Salmonella strains isolated from imported fish sold in open markets in Ouagadougou. One hundred and fifty-nine fish were collected from open markets. Salmonella were isolated from the fish using standard bacteriological procedures. Susceptibility to antibiotics was determined, and the whole genomes of the bacteria were sequenced. The DNA sequences were used to identify antibiotic resistance genes, mobile genetic elements such as plasmids were also identified, and Multilocus Sequence Type (MLST) genotypes were determined. Serotypes were determined from DNA sequences using SeqSero 2. Of the 159 fish samples analyzed, 28 (17.61%) were found to be contaminated with Salmonella. Among the isolated Salmonella strains, 6 different serotypes were found. The isolates were susceptible to all antibiotics tested. These results demonstrate the prevalence of Salmonella on imported fish in the open markets. Imported fish and the conditions where they are sold should be monitored to prevent potential health risks for consumers.

Technical Abstract: Fish is an excellent source of protein and vitamins for humans, but improperly handled fish can expose consumers to pathogenic bacteria. The aim of this study was to isolate and characterize the genomes of Salmonella strains isolated from imported fish sold in open market in Ouagadougou. One hundred and fifty-nine fish were collected from open markets. Isolation of Salmonella from fish samples was performed using standard bacteriological procedures. Antimicrobial susceptibility was determined by broth microdilution. Whole Genome Sequencing was done to further study antibiotic resistance genes, plasmid replicons, and Multilocus Sequence Type (MLST) types. Serotyping was done using SeqSero 2. Out of the 159 fish samples analyzed, 28 (17.61%) were found to be contaminated with Salmonella. Among the isolated Salmonella strains, 6 different serotypes, Nima, Liverpool, Kokomlemle, Gaminara, Derby and Tennessee, were found using SeqSero2. Not all isolates had an identifiable serotype. S. Tennessee was the predominant serotype. All the isolates possessed at least one resistance gene. The aac6-Iaa and aac6-Iy conferring resistance to aminoglycosides were the most prevalent gene found in the strains; the genes were non-functional. The gene fosA7 conferring resistance to Fosfomycin was detected in two strains but isolates were not tested for susceptibility to this drug. The isolates were susceptible to all drugs tested using broth microdilution. All the S. Nima isolates were of MLST 2258, Gaminara was ST 5197; Liverpool was ST 1959; Derby was ST 3997; Kokomlemle was ST 2696. The serotype Tennessee isolates gave many different STs such as ST 3763; 3997; 3135 and 10 strains of S. Tennessee gave Unknown ST. The presented results highlight the prevalence of Salmonella on imported fish purchased from the open markets. More attention should be paid regarding fish selling conditions in the country to prevent the potential health risk for consumers.