Staphylococci

STAPHYLOCOCCI (from Greek staphyla - grape cluster and coccus - coccus), micrococci of regular spherical shape, with an average diameter of 0.8 μm, immotile, belong to the group of pus-forming microbes (pyococcus). In both cultures and pathological material, they form clusters of several individuals, which creates a resemblance to a grape cluster (hence the name - grape-like coccus). Pathogenic S. are divided according to the color of the pigment they produce into golden (St. aureus), white (St. albus), and orange (St. citreus). S. are easily stained by all basic and some aniline dyes; they are not decolorized by Gram's method. They grow on all ordinary nutrient media, showing no special requirements as to composition or reaction. In broth (and peptone water) they cause uniform cloudiness, and with prolonged growth - a mucous precipitate at the bottom of the flask. On agar - growth in the form of round colonies with even edges, colored by the pigment in the corresponding color. On potato - good growth with pigment formation. They slowly liquefy gelatin; when inoculated by puncture, liquefaction begins 2-3 days later. In addition to the proteolytic enzyme, they also rennet. They grow poorly on Endo medium. S. are facultative anaerobes and do not need free oxygen in the air for their growth. Pigment formation occurs only in the presence of oxygen; the best temperature for this is 20-22°C. The pigment is secreted by the microbe to the outside and is an excretory product of the bacterial cell; it is insoluble in water. S. decompose grape, milk, and cane sugars, mannitol, glycerin, maltose, levulose, and galactose. Their fermentative activity is not constant. S. produce various toxic substances that are destructive to animal cells. These include leukocidin (see) and staphylolysin, or pyolysin, which acts on red blood cells. Like leukocidin, staphylolysin is produced by S. in the surrounding environment and is detected there from the 7th day of growth; it is inactivated at 50-57°C but then restored. Rabbit erythrocytes are most susceptible to staphylolysin. It cannot be considered finally resolved whether leukocidin and staphylolysin are identical; however, it can be thought that the matter concerns the same toxin, secreted by S. and acting not only on leukocytes and erythrocytes but also on other cells of the body (skin, subcutaneous tissue, kidneys). The nature of this toxic action is the same in all cases - degeneration and then necrosis. Nelis and Picard summarize the action of staphylococcal toxin as follows. Staphylococcal toxin is a poison which, in the appropriate dose, can kill a rabbit in a few minutes, causing the breakdown of sensitive cells, primarily liver and erythrocytes. S. is sufficiently resistant to physical and chemical influences. At 56° it dies in 2-4 hours, at 80° - in 10 minutes, at 100° - in a few seconds. Sublimate (5:1,000) kills it in 1 hour, 1-5% carbolic acid - in 35 minutes. Man has the greatest susceptibility to S., and among laboratory animals - the rabbit. With intravenous injection in a rabbit, general sepsis develops, which kills it when 0.1 cm³ of broth culture is injected in 24-96 hours. When introduced into the blood, S. relatively quickly settle in the organs, forming abscesses in them; they appear earliest in the heart muscle and kidneys, also often in joints; other organs are affected only if the process is prolonged. When using very virulent cultures, sometimes endocarditis develops on the mitral and tricuspid valves. With prolonged existence of sepsis, S. are excreted with bile, which can lead to catarrhal inflammation of the gallbladder. A subcutaneous abscess can be caused only by using a very large amount of culture. In guinea pigs and white mice, the introduction of S. gives inconsistent results. S. are inhabitants of the skin of healthy people (according to I. Koch - in 10%) and can be the cause of various lesions of it (skin abscesses, furunculosis, pemphigus, phlegmon, etc.).---Among other diseases due to S., it is necessary to name osteomyelitis, subphrenic abscess, brain abscess, lung abscess, otitis, cystitis, etc. Staphylococcal sepsis usually occurs by opening a local staphylococcal focus into the bloodstream; furuncles of the upper lip, lung abscesses, tonsil abscesses, etc. are particularly dangerous in this regard. Most often, staphylococcal sepsis has the character of pyemia.--Staphylococcal diseases do not leave immunity behind them, although both vaccination with S. and the course of a staphylococcal disease lead to the appearance of antibodies in the serum (antileukocidin, antihemolysin, bactericidal substances, opsonins); however, of these, during the disease, the appearance of antihemolysin has been proven with certainty; as for other antibodies, their content in a person who has had a staphylococcal disease does not exceed their content in the serum of a healthy person. In the treatment of staphylococcal diseases, autovaccination and antivirus occupy a prominent place; attempts are also made to use chemotherapeutic agents (flavicide).