Frequency of enterotoxins, toxic shock syndrome toxin-1, and biofilm formation genes in Staphylococcus aureus isolates from cows with mastitis in the Northeast of Brazil

Abstract

Staphylococcus aureus is among the microorganisms more frequently associated with subclinical bovine mastitis. S. aureus may produce several virulence factors. This study aimed at determining the frequency of virulence factors such as enterotoxins, toxic shock syndrome toxin 1, and ica adhesion genes. In addition, we assessed antimicrobial drug resistance in S. aureus isolated from clinical and subclinical cases of mastitis. A total of 88 cows with clinical or subclinical mastitis were sampled, resulting in 38 S. aureus isolates, from which 25 (65.78%) carried toxin genes, including seb, sec, sed, tst, and icaD adhesion gene. These S. aureus isolates belong to 21 ribotypes and three S. aureus strains belonged to the same ribotype producing ica adhesion gene. Approximately 90% of S. aureus strains obtained in our study demonstrated multiple resistance to different antimicrobial agents. The most efficacious antimicrobial agents against the isolates were gentamicin, amoxicillin, and norfloxacin. Gentamicin was the most efficacious agent inhibiting 78.95% of the S. aureus isolates. The least efficacious were penicillin, streptomycin, and ampicillin. Our results can help in understanding the relationship between virulence factors and subclinical mastitis caused by S. aureus. Further research about diversity of S. aureus isolates and genes responsible for the pathogenicity of subclinical mastitis is essential.

Staphylococcus aureus Exotoxins and Their Detection in the Dairy Industry and Mastitis

“…Comparison of S. aureus genotypes isolated from either bovine, ovine, or caprine animals suffering from mastitis suggests the existence of specific S. aureus clonal types for each of the animal groups; the bacterium appears to have developed distinct virulence mechanisms to specifically target these three ruminant groups. These studies centered on the prevalence of individual toxins, with the aim of understanding the role of each particular toxin in the development of mastitis [12,13,[15][16][17][18][19][20][21][22][23]. Indeed, Vaughn and coworkers [13] studied the genotypes of individual S. aureus isolates, identified from cases of bovine mastitis in east Tennessee.…”

“…The entB and entC1 genes, encoding the SEB and SEC proteins respectively, were the first genes amplified by PCR in dried skim milk powder; while dairy products, meat, and traditional sweets have been analyzed using multiplex PCR to detect the S. aureus 16s rRNA, as well as the sea, seb, sec, sed, and see genes [52]. Several studies have used multiplex PCR to amplify a variety of toxin genes, in combination with genes associated with biofilm formation, such as icaA and icaD [20], clumping factor (clfA), or protein A (spa) [15]; these co-amplifications helped establish the relationships between those genes, as well as furthering research into their role in staphylococcal infections. In addition, both PCR and ELISA techniques have been successfully used to investigate the presence of a variety of genes in beef and lamb meat; these genes include those corresponding to SE (sea, seb, sec, sed, and see), several SEI toxins (seg, seh, sei, sej, sel, sem, and seo), exfoliative toxins (eta and etb), and the toxic shock syndrome 1 toxin (tst) [40].…”

Genotypic and phenotypic characterization of biofilm production by Staphylococcus aureus strains isolated from bovine intramammary infections in Colombian dairy farms

“…The biofilm formation ability of S. aureus is an important virulence factor associated with chronic IMI, which can be difficult to detect within herds (Cucarella et al., 2004; Gomes et al., 2016). On a regular basis, subclinical mastitis diagnosis is performed using the California mastitis test (CMT) and somatic cell count (SCC) (Costa et al., 2018). However, Petzer et al.…”

“…(2004), who also observed that 22.6% of infected cows were incorrectly classified as uninfected with the SCC criteria (<200.000 cells/mL), when in fact these cows were infected with the genotypes best capable of forming biofilms. These microorganisms can remain undetected in the udder, the biofilm-forming strains may cause misdiagnosis of IMI, allowing the persistence of this pathogen in dairy herds (Costa et al., 2018; Cucarella et al., 2004). In this work, we found that 81.26% of S. aureus isolates were biofilm formers in vitro , which supports results shown by Coelho et al.…”

A new direction of scientific research in treatment of mastitis in milk animals

“…Íàèáîëåå ýôôåêòèâíûìè ïðîòèâîìèêðîáíûìè ñðåäñòâàìè ïðîòèâ èçîëÿòîâ áûëè ãåíòàìèöèí, àìîêñèöèëëèí è íîðôëîêñàöèí. Ìåíåå ýôôåê-òèâíûìè áûëè ïåíèöèëëèí, ñòðåïòîìèöèí è àìïèöèëëèí [2,3,4,8].…”