Staphylococcus aureus Isolated from Ruminants with Mastitis in Northern Greece Dairy Herds: Genetic Relatedness and Phenotypic and Genotypic Characterization

Abstract

Staphylococcus aureus is the most common mastitis-related pathogen in dairy cattle, goats, and sheep worldwide. However, the population structure and genomic characteristics of mastitis-associated S. aureus in small ruminants are limited. Furthermore, the genotypic and phenotypic characteristics involved in the pathogenicity of S. aureus have been thoroughly defined, yet their association with the severity of mastitis is not fully established. Here, we performed genotyping by pulsed-field gel electrophoresis (PFGE) and spa analyses to assess the genetic diversity and relatedness of 162 S. aureus strains recovered from clinical mastitis (CM) and subclinical mastitis (SCM) cases from goats, sheep, and bovines. PFGE analysis revealed 108 distinguishable pulsotypes and 3 main clusters that comprised isolates from the three host species, while according to spa typing, 32 different spa types were identified. Genotypic analysis revealed a spreading of genetically related or indistinguishable S. aureus strains among ovine, caprine, and bovine farms of distant geographical regions. In total, 28 different staphylococcal enterotoxin (SE) gene profiles were observed, revealing a diverse range of SE genes among isolates. By evaluating the antimicrobial resistance, we found low phenotypic antimicrobial resistance among all ruminant isolates. We also performed multiple correspondence analysis, which indicated that the presence of the sec gene, biofilm production, and high autoaggregation ability are associated with CM cases.

Phenotypic and genotypic study on antibiotic resistance and pathogenic factors of <em>Staphylococcus aureus</em> isolates from small ruminant mastitis milk in South of Italy (Sicily)

“…In this study, the mecA gene was detected in one of the S. aureus strains only in contrast to a mecA positive prevalence of 4.5% detected in S. aureus isolated from food sources (Vitale et al, 2018), mainly derived from cow-milk of Ragusa province where a higher prevalence of mecA has been detected in people working in bovine farms (Antoci et al, 2013). This result agrees also with what was found in other studies on small ruminants (Vyletelová et al, 2011;Virdis et al, 2010;Kotzamanidis et al, 2021) and confirms low prevalence of MRSA in sheep and goats' milk (Caruso et al, 2016) and dairy products (Basanisi et al, 2016). The high presence of tet(K) and tet(M) (20.5%) suggests an overuse of broad-spectrum antibiotics such as tetracyclines in sheep and goat diseases.…”

“…However, increased in δT 2 group suggesting the possibility that toxigenic S. aureus isolates are spreading with the time in animal herds. In a previous report in Greece the presence of the staphylococcal enterotoxin C (SEC) was more related to the mastitis milk (Kotzamanidis et al ., 2021 ). Exfoliative toxins genes were not detected, according with previous studies on S. aureus isolates from bovine mastitis (Endo et al ., 2003 ; Vitale et al ., 2019 ).…”

Antimicrobial and Methicillin Resistance Pattern of Potential Mastitis-Inducing Staphylococcus aureus and Coagulase-Negative Staphylococci Isolates from the Mammary Secretion of Dairy Goats

“…Similarly, a more recent study on the causative agents of subclinical mastitis in dairy goats reared in Greek farms reported CoNS (50.2%) as the main causative agent followed by CoPS (34.5%), while also determining the incidence of subclinical mastitis at 24.1% and 31.7% in two successive years [ 11 ]. Of the CoPS, S. aureus represents the majority of the isolates, with a prevalence of 29% in lactating goats with subclinical mastitis, while this pathogen is also involved in cases of clinical mastitis [ 12 , 13 ].…”

“…Taking into account the routine use of β-lactams as mastitis treatment in dairy goats, this practice may facilitate the emergence of methicillin-resistant staphylococci in the produced milk and dairy products [ 15 ]. In several studies, S. aureus and CoNS strains resistant to one or more antimicrobials and even multi-drug resistant (MDR) strains have been isolated from goat milk collected from individual animals with [ 13 , 16 , 17 , 18 ] or without mastitis [ 19 , 20 ], with a high frequency of resistance to various members of the β-lactams groups commonly observed. Concerning the presence of methicillin-resistant S. aureus (MRSA) in goats with clinical/subclinical mastitis, the prevalence of such isolates was generally considered very low based on the detection of mecA and mecC genes [ 12 , 13 , 16 ].…”

“…In several studies, S. aureus and CoNS strains resistant to one or more antimicrobials and even multi-drug resistant (MDR) strains have been isolated from goat milk collected from individual animals with [ 13 , 16 , 17 , 18 ] or without mastitis [ 19 , 20 ], with a high frequency of resistance to various members of the β-lactams groups commonly observed. Concerning the presence of methicillin-resistant S. aureus (MRSA) in goats with clinical/subclinical mastitis, the prevalence of such isolates was generally considered very low based on the detection of mecA and mecC genes [ 12 , 13 , 16 ]. MRSA strains harboring the mecA gene have also been isolated from milk samples of clinically healthy goats [ 18 ].…”