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Prevalence and characterization of methicillin-resistant Staphylococcus aureus carrying mecA or mecC and methicillin-susceptible Staphylococcus aureus in dairy sheep farms in central Italy.
J Dairy Sci. 2017 Oct; 100(10):7857-7863.JD

Abstract

Between January and May 2012, a total of 286 bulk tank milk samples from dairy sheep farms located in central Italy were tested for the presence of Staphylococcus aureus. One hundred fifty-three samples were positive for S. aureus (53.5%), with an average count of 2.53 log cfu/mL. A total of 679 S. aureus colonies were screened for methicillin resistance by the cefoxitin disk diffusion test, and 104 selected cefoxitin-susceptible isolates were also tested for their susceptibility to other antimicrobials representative of the most relevant classes active against Staphylococcus spp. by using the Kirby-Bauer disk diffusion method. Two methicillin-resistant Staphylococcus aureus (MRSA) isolates, carrying respectively the mecA and the mecC genes, were detected in 2 samples from 2 different farms (prevalence 0.7%). The mecA-positive MRSA isolate was blaZ positive, belonged to spa type t127, sequence type (ST)1, clonal complex (CC)1, carried a staphylococcal cassette chromosome mec (SCCmec) type IVa, and was phenotypically resistant to all the β-lactams tested and to erythromycin, streptomycin, kanamycin, and tetracycline. The mecC-positive MRSA isolate was negative for the chromosomally or plasmid-associated blaZ gene but positive for the blaZ allotype associated with SCCmec XI (blaZ-SCCmecXI), belonged to spa type 843, ST(CC)130, carried a SCCmec type XI, and was resistant only to β-lactams. Both MRSA were negative for the presence of specific immune-evasion and virulence genes such as those coding for the Panton-Valentine leucocidin, the toxic shock syndrome toxin 1, and the immune evasion cluster genes. Regarding the presence of the major S. aureus enterotoxin genes, the mecC-positive MRSA tested negative, whereas the ST (CC)1 mecA-positive MRSA harbored the seh gene. Among the 104 methicillin-susceptible S. aureus isolates examined for antimicrobial susceptibility, 63 (60.58%) were susceptible to all the antimicrobials tested, and 41 (39.42%) were resistant to at least 1 antimicrobial. In particular, 23 isolates (22.12%) were resistant to tetracycline, 16 (15.38%) to sulfonomides, 14 (13.46%) to trimethoprim and sulfamethoxazole, and 9 (8.65%) to ampicillin, whereas only 1 isolate was resistant to both fluoroquinolones and aminoglycosides. The high prevalence of S. aureus found in bulk tank milk samples and the isolation of MRSA, although at a low prevalence, underlines the importance of adopting control measures against S. aureus in dairy sheep farms to minimize the risks for animal and public health. Moreover, this study represents the first report of mecC-positive MRSA isolation in Italy and would confirm that, among livestock animals, sheep might act as a mecC-MRSA reservoir. Although this lineage seems to be rare in dairy sheep (0.35% of farms tested), because mecC-positive MRSA are difficult to detect by diagnostic routine methods employed for mecA-positive livestock-associated MRSA, diagnostic laboratories should be aware of the importance of searching for the mecC gene in all the mecA-negative S. aureus isolates displaying resistance to oxacillin, cefoxitin, or both.

Authors+Show Affiliations

National Reference Centre for Ovine and Caprine Milk and Dairy Products Quality (CRELDOC), Istituto Zooprofilattico Sperimentale del Lazio e della Toscana "M. Aleandri" Via Appia Nuova 1411, 00178 Rome, Italy.General Diagnostic Department, National Reference Laboratory for Antimicrobial Resistance, Istituto Zooprofilattico Sperimentale del Lazio e della Toscana "M. Aleandri" Via Appia Nuova 1411, 00178 Rome, Italy.General Diagnostic Department, National Reference Laboratory for Antimicrobial Resistance, Istituto Zooprofilattico Sperimentale del Lazio e della Toscana "M. Aleandri" Via Appia Nuova 1411, 00178 Rome, Italy.National Reference Centre for Ovine and Caprine Milk and Dairy Products Quality (CRELDOC), Istituto Zooprofilattico Sperimentale del Lazio e della Toscana "M. Aleandri" Via Appia Nuova 1411, 00178 Rome, Italy.National Reference Centre for Ovine and Caprine Milk and Dairy Products Quality (CRELDOC), Istituto Zooprofilattico Sperimentale del Lazio e della Toscana "M. Aleandri" Via Appia Nuova 1411, 00178 Rome, Italy.National Reference Centre for Ovine and Caprine Milk and Dairy Products Quality (CRELDOC), Istituto Zooprofilattico Sperimentale del Lazio e della Toscana "M. Aleandri" Via Appia Nuova 1411, 00178 Rome, Italy.General Diagnostic Department, National Reference Laboratory for Antimicrobial Resistance, Istituto Zooprofilattico Sperimentale del Lazio e della Toscana "M. Aleandri" Via Appia Nuova 1411, 00178 Rome, Italy.General Diagnostic Department, National Reference Laboratory for Antimicrobial Resistance, Istituto Zooprofilattico Sperimentale del Lazio e della Toscana "M. Aleandri" Via Appia Nuova 1411, 00178 Rome, Italy.General Diagnostic Department, National Reference Laboratory for Antimicrobial Resistance, Istituto Zooprofilattico Sperimentale del Lazio e della Toscana "M. Aleandri" Via Appia Nuova 1411, 00178 Rome, Italy.General Diagnostic Department, National Reference Laboratory for Antimicrobial Resistance, Istituto Zooprofilattico Sperimentale del Lazio e della Toscana "M. Aleandri" Via Appia Nuova 1411, 00178 Rome, Italy.General Diagnostic Department, National Reference Laboratory for Antimicrobial Resistance, Istituto Zooprofilattico Sperimentale del Lazio e della Toscana "M. Aleandri" Via Appia Nuova 1411, 00178 Rome, Italy.General Diagnostic Department, National Reference Laboratory for Antimicrobial Resistance, Istituto Zooprofilattico Sperimentale del Lazio e della Toscana "M. Aleandri" Via Appia Nuova 1411, 00178 Rome, Italy.National Reference Centre for Ovine and Caprine Milk and Dairy Products Quality (CRELDOC), Istituto Zooprofilattico Sperimentale del Lazio e della Toscana "M. Aleandri" Via Appia Nuova 1411, 00178 Rome, Italy.General Diagnostic Department, National Reference Laboratory for Antimicrobial Resistance, Istituto Zooprofilattico Sperimentale del Lazio e della Toscana "M. Aleandri" Via Appia Nuova 1411, 00178 Rome, Italy. Electronic address: antonio.battisti@izslt.it.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

28780098

Citation

Giacinti, G, et al. "Prevalence and Characterization of Methicillin-resistant Staphylococcus Aureus Carrying mecA or mecC and Methicillin-susceptible Staphylococcus Aureus in Dairy Sheep Farms in Central Italy." Journal of Dairy Science, vol. 100, no. 10, 2017, pp. 7857-7863.
Giacinti G, Carfora V, Caprioli A, et al. Prevalence and characterization of methicillin-resistant Staphylococcus aureus carrying mecA or mecC and methicillin-susceptible Staphylococcus aureus in dairy sheep farms in central Italy. J Dairy Sci. 2017;100(10):7857-7863.
Giacinti, G., Carfora, V., Caprioli, A., Sagrafoli, D., Marri, N., Giangolini, G., Amoruso, R., Iurescia, M., Stravino, F., Dottarelli, S., Feltrin, F., Franco, A., Amatiste, S., & Battisti, A. (2017). Prevalence and characterization of methicillin-resistant Staphylococcus aureus carrying mecA or mecC and methicillin-susceptible Staphylococcus aureus in dairy sheep farms in central Italy. Journal of Dairy Science, 100(10), 7857-7863. https://doi.org/10.3168/jds.2017-12940
Giacinti G, et al. Prevalence and Characterization of Methicillin-resistant Staphylococcus Aureus Carrying mecA or mecC and Methicillin-susceptible Staphylococcus Aureus in Dairy Sheep Farms in Central Italy. J Dairy Sci. 2017;100(10):7857-7863. PubMed PMID: 28780098.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Prevalence and characterization of methicillin-resistant Staphylococcus aureus carrying mecA or mecC and methicillin-susceptible Staphylococcus aureus in dairy sheep farms in central Italy. AU - Giacinti,G, AU - Carfora,V, AU - Caprioli,A, AU - Sagrafoli,D, AU - Marri,N, AU - Giangolini,G, AU - Amoruso,R, AU - Iurescia,M, AU - Stravino,F, AU - Dottarelli,S, AU - Feltrin,F, AU - Franco,A, AU - Amatiste,S, AU - Battisti,A, Y1 - 2017/08/02/ PY - 2017/03/27/received PY - 2017/06/17/accepted PY - 2017/8/7/pubmed PY - 2018/6/6/medline PY - 2017/8/7/entrez KW - Staphylococcus aureus KW - mecA/mecC KW - methicillin-resistant Staphylococcus aureus KW - sheep milk SP - 7857 EP - 7863 JF - Journal of dairy science JO - J. Dairy Sci. VL - 100 IS - 10 N2 - Between January and May 2012, a total of 286 bulk tank milk samples from dairy sheep farms located in central Italy were tested for the presence of Staphylococcus aureus. One hundred fifty-three samples were positive for S. aureus (53.5%), with an average count of 2.53 log cfu/mL. A total of 679 S. aureus colonies were screened for methicillin resistance by the cefoxitin disk diffusion test, and 104 selected cefoxitin-susceptible isolates were also tested for their susceptibility to other antimicrobials representative of the most relevant classes active against Staphylococcus spp. by using the Kirby-Bauer disk diffusion method. Two methicillin-resistant Staphylococcus aureus (MRSA) isolates, carrying respectively the mecA and the mecC genes, were detected in 2 samples from 2 different farms (prevalence 0.7%). The mecA-positive MRSA isolate was blaZ positive, belonged to spa type t127, sequence type (ST)1, clonal complex (CC)1, carried a staphylococcal cassette chromosome mec (SCCmec) type IVa, and was phenotypically resistant to all the β-lactams tested and to erythromycin, streptomycin, kanamycin, and tetracycline. The mecC-positive MRSA isolate was negative for the chromosomally or plasmid-associated blaZ gene but positive for the blaZ allotype associated with SCCmec XI (blaZ-SCCmecXI), belonged to spa type 843, ST(CC)130, carried a SCCmec type XI, and was resistant only to β-lactams. Both MRSA were negative for the presence of specific immune-evasion and virulence genes such as those coding for the Panton-Valentine leucocidin, the toxic shock syndrome toxin 1, and the immune evasion cluster genes. Regarding the presence of the major S. aureus enterotoxin genes, the mecC-positive MRSA tested negative, whereas the ST (CC)1 mecA-positive MRSA harbored the seh gene. Among the 104 methicillin-susceptible S. aureus isolates examined for antimicrobial susceptibility, 63 (60.58%) were susceptible to all the antimicrobials tested, and 41 (39.42%) were resistant to at least 1 antimicrobial. In particular, 23 isolates (22.12%) were resistant to tetracycline, 16 (15.38%) to sulfonomides, 14 (13.46%) to trimethoprim and sulfamethoxazole, and 9 (8.65%) to ampicillin, whereas only 1 isolate was resistant to both fluoroquinolones and aminoglycosides. The high prevalence of S. aureus found in bulk tank milk samples and the isolation of MRSA, although at a low prevalence, underlines the importance of adopting control measures against S. aureus in dairy sheep farms to minimize the risks for animal and public health. Moreover, this study represents the first report of mecC-positive MRSA isolation in Italy and would confirm that, among livestock animals, sheep might act as a mecC-MRSA reservoir. Although this lineage seems to be rare in dairy sheep (0.35% of farms tested), because mecC-positive MRSA are difficult to detect by diagnostic routine methods employed for mecA-positive livestock-associated MRSA, diagnostic laboratories should be aware of the importance of searching for the mecC gene in all the mecA-negative S. aureus isolates displaying resistance to oxacillin, cefoxitin, or both. SN - 1525-3198 UR - https://www.unboundmedicine.com/medline/citation/28780098/Prevalence_and_characterization_of_methicillin_resistant_Staphylococcus_aureus_carrying_mecA_or_mecC_and_methicillin_susceptible_Staphylococcus_aureus_in_dairy_sheep_farms_in_central_Italy_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0022-0302(17)30735-X DB - PRIME DP - Unbound Medicine ER -