Characterisation ofStaphylococcus aureusstrains isolated from mastitis bovine milk in Argentina

Abstract

The study reported in this Research Communication was conducted to characterise Staphylococcus aureus isolates recovered from mastitic bovine milk from dairy herds in Argentina. A total of 829 mastitic milk samples, both clinical and subclinical, were collected from 21 farms by veterinarians and submitted to the laboratory for testing from which 229 S. aureus isolates were recovered, an isolation rate of 28·1%. These isolates were tested for susceptibility to the antibiotics penicillin, erythromycin and clindamycin. Of the 229 isolates, 53 (23·1%) were resistant to penicillin, 31 (13·5%) to erythromycin and 28 (12·2%) to clindamycin. All isolates were negative for the mecA, mecC and pvl genes by PCR. Southernblot hybridisation revealed that the ermC gene was located on plasmid bands. Eighty isolates were randomly selected from the 229 for further characterisation. Restriction analysis of chromosomal DNA with Cf9I followed by PFGE of the 80 isolates revealed 23 distinct pulsotypes at 80% similarity. Seven major types (A, B, N, P, S, T, U and V) accounted for 68·7% of these isolates and 12 pulsotypes (A, B, F, G, J, K, M, N, P, S, T and U) occurred on more than one farm indicating genetic diversity within the farms. MLST of a representative isolate from dominant types identified the STs 97 705, 746, 2102 and 2187 with ST97 being the most predominant. Antibiotic susceptibility testing showed that 53·7% of the 80 randomly selected isolates were resistant to at least one of the three antibiotics tested. To our knowledge, this study represents the first large scale molecular studies on S. aureus isolates from dairy farms in Argentina.

Molecular Typing and Antimicrobial Susceptibility Profile of <em>Staphylococcus aureus</em> Isolates Recovered from Bovine Mastitis and Nasal Samples

“…We also showed that one S. aureus strain was widespread in the two herds investigated, although the herds are geographically distant; this S. aureus strain was responsible for almost all IMIs, probably because it is well adapted to the udder, leading to the persistence of IMIs. Thus, our results are in agreement with other reports that indicated that few specialized S. aureus types with broad geographic distribution are responsible for most of the IMIs in dairy herds (Srednik et al 2018).…”

Identification of staphylococci causing mastitis in dairy cattle from Algeria and characterization ofStaphylococcus aureus

“…These isolates were all grouped into CC97. This lineage is prevalent among bovine mastitis isolates from Algeria (Akkou et al ), from Brazil (Rabello et al ), the United Kingdom (Sung et al ), Tunisia (Ben Said et al ), China (Li et al ) and Argentina (Srednik et al ).…”

“…Influences from breed, age and lactation stage of the animal have been described (Haftu et al ; Oliveira et al ). Staphylococcus aureus is one of the most important bacterial pathogens causing bovine mastitis (Tenhagen et al ; Wang et al ; Lundberg et al ; Srednik et al ). Mastitis caused by this bacterium has a lower cure rate than for most of the other bacteria (Sartori et al ; Srednik et al ).…”

“…Staphylococcus aureus is one of the most important bacterial pathogens causing bovine mastitis (Tenhagen et al ; Wang et al ; Lundberg et al ; Srednik et al ). Mastitis caused by this bacterium has a lower cure rate than for most of the other bacteria (Sartori et al ; Srednik et al ). Its success as a versatile pathogen is in part due to the bacterium’s individual equipment with virulence factors, including microbial surface components recognizing adhesive matrix molecule (MSCRAMM) genes, hemolysin genes ( hla and hlb ), thermonuclease gene ( nuc ), coagulase gene ( coa ), protease genes, superantigen genes and toxin genes (Kot et al ; Strauß et al ; Wang et al ).…”

PHENOTYPIC RESISTANCE TO ANTIBIOTICS OF Staphylococcus aureus STRAINS ISOLATED FROM COW MILK

“…Только у 7 выделенных штаммов (6,8 %) выявили чувствительность ко всем исследуемым антибиотикам, тогда как 96 изолятов оказались устойчивы по крайней мере к одному из них. Другими авторами было установлено очевидное развитие резистентности S. aureus к пенициллину, ампициллину, эритромицину (40,42,43 Устойчивости к оксациллину и цефокситину у всех исследованных нами штаммов мы не обнаружили, что позволяет отнести их к метициллин-чувствительным S. aureus MSSA. В случае MSSA считается, что пенициллин превосходит по действию оксациллин, но только если штаммы не продуцируют пенициллиназу (48).…”