Staphylococcus aureus

The most important species in the genus Staphylococcus is S. aureus. They are natural inhabitant of human and animal skin but sometimes they can cause infections affecting many organs. Staphylococci form clusters when grown in liquid or solid media hence the name staphylococcus (Staphyle means bunch of grapes and kokkos means a grain or a berry in Greek) (Fig. 6.1). In 1871, Von Recklinghausen, a German scientist observed cocci in a diseased kidney and called them “micrococci.” Later, on the basis of cell arrangements, Billroth (1874) classified them as “monococcus,” “diplococcus,” “streptococcus,” and “gliacoccus.” In 1880, Sir Alexander Ogston, a Scottish surgeon and Louis Pasteur, a French scientist confirmed that cocci-forming organisms are capable of causing disease. Later, Ogston coined the name “Staphylococcus.” In 1914, Barber discovered that a toxin substance produced by staphylococci was responsible for staphylococcal food poisoning. Staphylococci are mostly associated with community-acquired and nosocomial infections and may be life threatening in immunodeficient conditions. Some staphylococci are methicillin-resistant (MRSA) and vancomycin-resistant, and infection caused by these resistant strains may be fatal because of lack of alternative antibiotics. Most staphylococci are responsible for skin infections such as boil, carbuncle, and furuncle and some cause food poisoning resulting in severe vomiting and diarrhea. Staphylococci also cause mastitis in cow and also cause joint infection leading to edema and arthritis.