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

Abstract

Staphylococcus spp. is an important mastitis-inducing zoonotic pathogen in goats and is associated with antimicrobial resistance (AMR). The objectives of this study were to determine the prevalence and composition of staphylococci in individual mammary secretion (MS) samples of clinically healthy goats and to evaluate the phenotypic AMR pattern and the presence of methicillin resistance in the Staphylococcus spp. strains. Staphylococcus spp. isolates (n = 101) from the MS samples (n = 220) were identified to species level using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The antimicrobial susceptibility testing included a disk diffusion assay and the determination of the minimum inhibitory concentrations (MIC) of resistant strains (n = 46). Presumptive methicillin-resistant strains (n = 9) were assessed for the presence of mecA, mecC and SCCmec/orfx genes. Staphylococcus spp. isolates were recovered from 45.9% of the MS samples, of which, 72.3% was identified as coagulase-negative staphylococci (CoNS), with the remaining being Staphylococcus aureus. CoNS and S. aureus were most commonly resistant to ampicillin (56.2% and 57.1%, respectively), penicillin (26.0% and 39.3%, respectively), amoxicillin (26 % and 25 %, respectively) and cephalexin (12.3% and 25%, respectively) in the disk diffusion method. CoNS exhibited a broader AMR pattern and a higher percentage of resistant strains than S. aureus in the disk diffusion and MIC methods. Of the nine oxacillin- and cefoxitin-resistant strains, three S. aureus and five CoNS strains carried the mecA gene and, thus, were identified as methicillin-resistant. The mecC gene was not found in any of the studied strains. The presence of AMR and methicillin resistance in caprine S. aureus and CoNS poses a concern for animal and public health.

Virulence Mechanisms of Staphylococcal Animal Pathogens

“…In another study analyzing Belgian and Norwegian isolates from milk samples, including non-S. aureus staphylococci, resistance to trimethoprimsulfonamide was frequent in S. epidermidis and S. haemolyticus, while mecA was harbored in 10 out of 64 isolates from Belgium but was absent from isolates obtained in Norway [160]. These studies also indicated that frequency of the mecC mecA-homolog, which was first described in 2011 [144], appears to still be very low in cattle, and similar findings were achieved in goats [161].…”

In Vitro Interaction between Mycoplasma agalactiae and Small Ruminants’ Endogenous Bacterial Strains of Enterococcus spp. and Coagulase-Negative Staphylococcus

“…This Staphylococcus sp. has mostly been associated with the human species; thus, inadequate milking practices have been presumed to be the reason for its presence in goat mammary secretions [ 37 ]. The importance of Staphylococcus as a pathogen in the mammary gland of small ruminants and its importance in public health raises a great interest in the scientific community [ 36 , 60 , 61 , 62 , 63 ].…”

“…In a recent study, Staphylococcus spp. were isolated from clinically healthy goats (45.9%); 72.3% of the isolates were identified as CNS, and the remaining 27.7% were identified as S. aureus [ 37 ]. Another study suggested that the staphylococcal bacterial community can produce inflammation in the mammary gland, acting as opportunist pathogens in case of dysbiosis, although they could also be a defense barrier against the entrance of pathogens [ 38 ].…”

In Vitro Pharmacological Activity, and Comparison GC-ToF-MS Profiling of Extracts from Cissus cornifolia (Baker) Planch

“…The maintenance of milking machines, hazard identification and critical control point (HACCP), and proper disinfection of other utensils used in milking are general measures to prevent new cases of mastitis [ 52 , 53 ]. Other authors have proposed the use of metabolomics as a tool to identify the biomarkers of mastitis as the key to controlling mastitis [ 54 , 55 , 56 ]. Worldwide, mastitis is well known to infect milk and result in major agricultural losses and various human infections resulting from ingesting infected milk.…”