Staphylococcus aureus

History

    Staphylococcus aureus was first isolated from the abscess pus in the knee joint in 1880. In fact, 20% to 50% of people are long-term carriers of Staphylococcus aureus, mainly on the skin.

Species characteristics

    Staphylococcus is a Gram-positive bacterium, no spore formation, facultative anaerobic, inability to move, catalase-positive or negative, cell globular, paired or clusters forming bunches of grapes, the name of which is also related to this form. Staphylococcus can grow in food and grow in animals from 7 degrees Celsius to about 48 degrees Celsius. The optimal temperature is 35 degrees Celsius, 7.0-7.5 is the optimum pH range, but it can also grow at pH 4.5. Staphylococcus can grow under low water activity conditions, even as low as 0.8, and therefore can tolerate high salt and high sugar. The ham (salt) and pie (sugar) contaminated by it often become the culprit of foodborne disease outbreaks.

Pathogenicity

    In foods, Staphylococcus aureus causes disease by causing human gastroenteritis (nausea, vomiting, abdominal cramps, diarrhea) mainly through the production of heat-stable enterotoxin. Ingestion of contaminated food can occur within 30min-8h, usually 2-4h. The severity of symptoms is related to the sensitivity of the population to enterotoxin, toxin intake, and immune status.

    In hospitals, methicillin-resistant Staphylococcus aureus (MRSA) is increasingly becoming an important source of nosocomial infections, posing a serious threat to patients undergoing surgery and immunodeficiency. Staphylococcus aureus infections usually invade from the skin, open wounds, and can flow through the blood system to the body.

Genome

    Staphylococcus aureus has a genome size of approximately 2.9M and a predicted number of genes encoding around 3,000. Staphylococcus aureus encodes dozens of toxins as well as some host-invasive proteins. From the perspective of MLST classification, the human-related pedigrees are mainly CC1, CC5, CC8, CC12, CC15, CC22, CC25, CC30, CC45, CC51, CC30. MRSA mainly covers CC1, CC5, CC8, CC22, CC30 (including ST36) and CC45. The lineages associated with animals are mainly CC151, CC771, CC188, CC97, CC130, etc. As of July 2020，9,841 Staphylococcus aureus genomes have been published on NCBI,the sequences file from GenBank。