Characteristics ofStaphylococcus aureusSmall Colony Variant and Its Parent Strain Isolated from Chronic Mastitis at a Dairy Farm in Beijing, China

Abstract

Staphylococcus aureus is a major pathogen associated to bovine mastitis and has the ability to form a slow-growing population termed the small colony variants (SCVs). From 20 samples of 5 chronic S. aureus cases, 1 SCV isolate (SCV102) was recovered simultaneously with 1 of 8 S. aureus isolates. SCV102 showed auxotrophy for thymidine and had a slow growth rate. Intracellular persistence in human mammary epithelial cells (HBL100cell line) monolayer revealed that SCV102 isolate had minimal cytopathological effects compared with its parent strains. SCV102 isolate and its parent strain S. aureus 101 indicate similar resistant pattern to four antibiotics. On the contrary, the minimal inhibitory concentrations values for chloramphenicol and sulfadimethoxine were much higher in SCV102 than that of S. aureus 101. To the best of our knowledge this is the first time the isolation of S. aureus SCV102 from a persistent bovine mastitis has been reported in Beijing (China). This study suggests that SCV102 isolate may be an important contributor to persistent bovine mastitis.

Reduced Innate Immune Response to a Staphylococcus aureus Small Colony Variant Compared to Its Wild-Type Parent Strain

“…Some S. aureus strains are capable of switching to an alternative Small Colony Variant (SCV) phenotype, allowing their survival under stressful conditions (Proctor et al, 2006; Bui et al, 2015b). S. aureus SCVs have been identified for many decades (Jensen, 1957), but only sparked more research interest in recent years when they were found to be associated with chronic recurrent infections in both humans (Schneider et al, 2008; Maduka-Ezeh et al, 2012; Wolter et al, 2013; Tande et al, 2014; Masoud-Landgraf et al, 2016) and animals (Atalla et al, 2008; Alkasir et al, 2013). …”

Staphylococcus aureuspersistence properties associated with bovine mastitis and alternative therapeutic modalities

“…Their colonies are ten times smaller than the parent strain (Atalla et al 2008), nonpigmented, nonhemolytic and resistant to aminoglycosides. They require more than 18 h of incubation to be coagulase-positive (Attala et al 2008;Attala et al 2011;Alkasir et al 2013). Their small size on tryptic soy or Mueller-Hinton agar is often due to auxotrophy for thiamine, menadione or hemin (Proctor et al 1998).…”

“…2011; Alkasir et al . 2013). Their small size on tryptic soy or Mueller–Hinton agar is often due to auxotrophy for thiamine, menadione or hemin (Proctor et al .…”

Small Colony Variant of Methicillin-Resistant Staphylococcus pseudintermedius ST71 Presenting as a Sticky Phenotype

“…The SCV isolate S85 did not revert to the large-colony size, and the small phenotype was maintained after subcultivations and upon defrosting from Ϫ80°C storage. It is well known, conversely, that SCVs in S. aureus usually revert after discontinuation of the hostile conditions (6,7,17).…”

“…colonization and infections. Nevertheless, it is known that SCVs in S. aureus have an increased ability to survive within nonprofessional phagocytes that then behave as reservoirs for recurrent and chronic diseases and reduce exposure to certain antibiotics (6,7,17). Similarly to S. aureus SCVs, S85 showed decreased colony size and reduced coagulase activity.…”