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Genetic characterization and antimicrobial resistance of Staphylococcus aureus isolated from bovine milk in Tunisia.
Lett Appl Microbiol. 2016 Dec; 63(6):473-481.LA

Abstract

Staphylococcus aureus is a major agent of bovine mastitis in dairy herds, causing economic losses in dairy industry worldwide. In addition, milk and milk-products contaminated by Staph. aureus can cause harmful human diseases. The aim of this study was to characterize Staph. aureus strains isolated from dairy farms in Tunisia. Bulk tank milk (n = 32) and individual cow milk (n = 130) samples were collected during the period of 2013-2014. Forty-three Staph. aureus isolates were recovered and typed by spa typing, 16S-23S rRNA intergenic spacer (RS-PCR) and multiplex PCRs for 22 virulence genes. Antimicrobial resistance was also investigated with a disc diffusion test. A selected subsample of 22 strains was additionally genotyped by multilocus sequence typing. Seventeen spa types were recovered, and t2421 (n = 10), t521 (n = 6) and t2112 (n = 5) were the most common. Fourteen different RS-PCR genotypes grouped into 11 clusters were detected in our study, with predominance of the RVI genotype (n = 24). Eight sequence types were identified and Clonal Complex 97, corresponding to RS-PCR cluster R, was the most common (n = 10), followed by CC1 (n = 4), CC15 (n = 3) and other four accounting for one or two strains. Different combinations of virulence genes were reported, and enterotoxin genes were present in few strains (seh, n = 4; sea, n = 2; sea and seh, n = 2; sec and sel, n = 2). The majority of strains were resistant only to penicillin; only one strain was found to be multiresistant and no methicillin-resistant Staph. aureus was demonstrated. Our study reported the isolation of CC97 from bovine milk in Tunisia for the first time and confirmed the relevance of this lineage in intramammary infection in cows.

SIGNIFICANCE AND IMPACT OF THE STUDY

This paper describes the characteristics of Staphylococcus aureus isolated from bulk tank and individual cow milk in Tunisia. All strains were genotyped by spa typing and RS-PCR, a method based on the amplification of the 16S-23S rRNA intergenic spacer region, and multiplex PCRs for 22 virulence genes. A selected subsample of strains was also genotyped by multilocus sequence typing. All strains were tested for antimicrobial resistance. Our study evidences a predominance of strains belonging to Clonal Complex 97. Methicillin-resistant strains were not detected, and overall low level of antimicrobial resistance was reported.

Authors+Show Affiliations

Université de Tunis El Manar, Institut de la Recherche Vétérinaire de Tunisie, Tunis, Tunisie. Laboratory Wastewater Treatment, and Research Center of Water Technologies, Techno park Borj Cedria, Soliman, Tunisia.Université de Tunis El Manar, Institut de la Recherche Vétérinaire de Tunisie, Tunis, Tunisie.Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna, Lodi, Italy.Université de Tunis El Manar, Institut de la Recherche Vétérinaire de Tunisie, Tunis, Tunisie. Laboratory Wastewater Treatment, and Research Center of Water Technologies, Techno park Borj Cedria, Soliman, Tunisia.Institute of Agricultural Biology and Biotechnology, National Research Council, Lodi, Italy.Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna, Lodi, Italy.Piattaforma Genomica, Parco Tecnologico Padano, Lodi, Italy.Laboratory Wastewater Treatment, and Research Center of Water Technologies, Techno park Borj Cedria, Soliman, Tunisia.Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna, Lodi, Italy.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

27657910

Citation

Ben Said, M, et al. "Genetic Characterization and Antimicrobial Resistance of Staphylococcus Aureus Isolated From Bovine Milk in Tunisia." Letters in Applied Microbiology, vol. 63, no. 6, 2016, pp. 473-481.
Ben Said M, Abbassi MS, Bianchini V, et al. Genetic characterization and antimicrobial resistance of Staphylococcus aureus isolated from bovine milk in Tunisia. Lett Appl Microbiol. 2016;63(6):473-481.
Ben Said, M., Abbassi, M. S., Bianchini, V., Sghaier, S., Cremonesi, P., Romanò, A., Gualdi, V., Hassen, A., & Luini, M. V. (2016). Genetic characterization and antimicrobial resistance of Staphylococcus aureus isolated from bovine milk in Tunisia. Letters in Applied Microbiology, 63(6), 473-481. https://doi.org/10.1111/lam.12672
Ben Said M, et al. Genetic Characterization and Antimicrobial Resistance of Staphylococcus Aureus Isolated From Bovine Milk in Tunisia. Lett Appl Microbiol. 2016;63(6):473-481. PubMed PMID: 27657910.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Genetic characterization and antimicrobial resistance of Staphylococcus aureus isolated from bovine milk in Tunisia. AU - Ben Said,M, AU - Abbassi,M S, AU - Bianchini,V, AU - Sghaier,S, AU - Cremonesi,P, AU - Romanò,A, AU - Gualdi,V, AU - Hassen,A, AU - Luini,M V, Y1 - 2016/11/02/ PY - 2016/05/11/received PY - 2016/08/05/revised PY - 2016/09/17/accepted PY - 2016/11/3/pubmed PY - 2017/6/14/medline PY - 2016/9/23/entrez KW - Staphylococcus aureus KW - CC97 KW - antimicrobial resistance KW - bovine milk KW - genotyping KW - virulence genes SP - 473 EP - 481 JF - Letters in applied microbiology JO - Lett Appl Microbiol VL - 63 IS - 6 N2 - : Staphylococcus aureus is a major agent of bovine mastitis in dairy herds, causing economic losses in dairy industry worldwide. In addition, milk and milk-products contaminated by Staph. aureus can cause harmful human diseases. The aim of this study was to characterize Staph. aureus strains isolated from dairy farms in Tunisia. Bulk tank milk (n = 32) and individual cow milk (n = 130) samples were collected during the period of 2013-2014. Forty-three Staph. aureus isolates were recovered and typed by spa typing, 16S-23S rRNA intergenic spacer (RS-PCR) and multiplex PCRs for 22 virulence genes. Antimicrobial resistance was also investigated with a disc diffusion test. A selected subsample of 22 strains was additionally genotyped by multilocus sequence typing. Seventeen spa types were recovered, and t2421 (n = 10), t521 (n = 6) and t2112 (n = 5) were the most common. Fourteen different RS-PCR genotypes grouped into 11 clusters were detected in our study, with predominance of the RVI genotype (n = 24). Eight sequence types were identified and Clonal Complex 97, corresponding to RS-PCR cluster R, was the most common (n = 10), followed by CC1 (n = 4), CC15 (n = 3) and other four accounting for one or two strains. Different combinations of virulence genes were reported, and enterotoxin genes were present in few strains (seh, n = 4; sea, n = 2; sea and seh, n = 2; sec and sel, n = 2). The majority of strains were resistant only to penicillin; only one strain was found to be multiresistant and no methicillin-resistant Staph. aureus was demonstrated. Our study reported the isolation of CC97 from bovine milk in Tunisia for the first time and confirmed the relevance of this lineage in intramammary infection in cows. SIGNIFICANCE AND IMPACT OF THE STUDY: This paper describes the characteristics of Staphylococcus aureus isolated from bulk tank and individual cow milk in Tunisia. All strains were genotyped by spa typing and RS-PCR, a method based on the amplification of the 16S-23S rRNA intergenic spacer region, and multiplex PCRs for 22 virulence genes. A selected subsample of strains was also genotyped by multilocus sequence typing. All strains were tested for antimicrobial resistance. Our study evidences a predominance of strains belonging to Clonal Complex 97. Methicillin-resistant strains were not detected, and overall low level of antimicrobial resistance was reported. SN - 1472-765X UR - https://www.unboundmedicine.com/medline/citation/27657910/Genetic_characterization_and_antimicrobial_resistance_of_Staphylococcus_aureus_isolated_from_bovine_milk_in_Tunisia_ L2 - https://doi.org/10.1111/lam.12672 DB - PRIME DP - Unbound Medicine ER -