[8] More recently, molecular technologies like MALDI-TOF, DNA hybridization and PCR have become preferred over biochemical tests for their more rapid and accurate identifications.
Due to its ability to clot blood, S. pseudintermedius is subcategorized into a group of coagulase positive (CoPS) staphylococci.
[13] Previously, many S. pseudintermedius infections or isolates were identified as Staphylococcus intermedius, before its identification as a distinct species.
However, given that S. pseudintermedius is prevalent within the normal microbiota of numerous species, it is better identified as the agent of disease when a corresponding immune reaction is also observed.
[8] Where available, the need to identify immune reactors can be avoided by first inoculating the sample onto differential agar like Staphylococcus Medium 110,[19] which inhibit the growth of non-staphylococcal bacteria.
[20][8] This can be useful for differentiating S. pseudintermedius from coagulase-negative staphylococci, and from S. aureus which tends to be yellow and displays more variable hemolytic patterns on agar.
[20] More recently, studies using molecular identification methods have found that different S. pseudintermedius strains harbor more phenotypic diversity than previously thought.
[9][10][13] Molecular methods, like MALDI-TOF [24] and qPCR primers,[25] are the gold standard for accurately identifying the presence of the mecA gene, which confers resistance to beta-lactam drugs.
[2][34] Methicillin-resistant S. pseudintermedius (MRSP) has five major clonal complex (CC) lineages,[2] each with their own unique traits regarding genetic diversity, geographical distribution and antimicrobial resistance.
[38] As previously described, S. pseudintermedius, an opportunistic pathogen, is a part of the normal microbiome of the skin and mucous membranes in animals.
[20] Animals acquire this bacterium through vertical transmission with transfer of S. pseudintermedius from the mother's vaginal mucous membrane to their offspring during birth.
[20] A compromised immune system or tissue injury allows this bacterium to push past host defences leading to infection.
These include proteases, thermonucleases, coagulases,[40] DNAase, lipase, hemolysin, clumping factor, leukotoxin, enterotoxin,[6] protein A, and exfoliative toxin.
[40] Haemolysins, leukotoxins, exfoliative toxins, and enterotoxins are secreted[20] from the bacteria to modulate the host's immune response.
[7] Exfoliative toxin causes vesicle formation and erosion in epithelial cells resulting in splitting of the skin.
[20][7] S. pseudintermedius has been found to produce biofilms, an extracellular matrix of protein, DNA, and polysaccharide, which aids the bacteria in avoiding the host immune system and resisting drugs.
[6] Biofilms allow the bacteria to persist on medical equipment even after disinfection and adhere to host cells, a component of chronic infections.
[20] People at the highest risk for contracting this pathogen are pet owners and veterinarians due to their higher contact with dogs and to a lesser extent cats.
[6] There is an increasing prevalence of antibiotic resistance in S. pseudintermedius, specifically to methicillin, which makes it challenging to treat in humans.
[44][42][41] Veterinary dermatologists are exposed to animals with skin and soft infections that commonly possess MRSP (methicillin‐resistant Staphylococcus pseudintermedius).
[42][43] Hand washing, sterilizing equipment and hygiene practices should be implemented to decrease the spread of Staphylococcus infections.