PYIEMIC INFECTION The most important pus-producing bacteria — pyogenic micro organisms—are the following: 1. The Staphylococcus group (usually Staphylococcus pyogenes aureus, Fig. 107a, Plate 9). The masses of cocci are aggregated in the form of grapes, they are stained with basic aniline stains, not &color ized by Gram's method; on gelatine they grow either as small white dots or as gray membranes, they liquefy the gelatine giving it a yellow color; on agar they grow first as round white colonies which later on turn yellow, they do not liquefy agar; they render broth turbid.
They are extremely frequent and very resistant.
In the human body they are found in the recesses of the mucous membranes—in the mouth, the intestinal canal, and in all the cavities communicating with the outside world, in the nail-folds and in the folds of the skin. They may remain entirely innocuous until an injury or a damage to the tissues admits them into the body proper. They differ in virulence and pathogeny, they are the causes of many infec tions of wounds, abscesses, suppurations of joints, osteomyelitides. Staphylococcus pyogenes albus and Staphylococcus pyogenes citreus arc rarer varieties.
2. The Streptococci (Streptococcus pyogenes, Fig. 107b, Plate 9) are found in chains, they stain with aniline stains and with Grain's method, on gelatine they grow slowly without liquefying it, on agar and blood serum they form small translucent colonies which usually die in a few days; they render broth turbid.
These also are frequently found upon human beings and their sur roundings (see Streptococcus enteritis of infants).
When they enter the body they cause malignant suppurations, especially after they have once passed through the human body.
White mice and rabbits are very susceptible to this form of infec tion, usually dying after a few clays, frequently with the formation of numerous metastases. The different kinds of antisera (Marmorek, Tavel) arc very uncertain in their action, because the pathogeny of the different species of streptococci varies for animals and humans (Lexer).
3. The Diplococci pneumonia? (Frankel) (Fig. 107c, Plate 9) are closely related to the streptococci; they are usually found in pairs sur rounded by a common capsule which is hard to stain; occasionally they may be found in chains. This diplococcus is the cause of fibrinous pneumonia; it is found in suppurations of serous cavities which it reaches through the blood current. These suppurations are not quite as malig nant as those caused by streptococci. normal conditions it is found upon the mucous membrane of the oral and nasal cavities of many healthy people.
4. The Bacillus pyocyaneus is a small and very active rod which does not produce spores; it is stained with aniline dyes, decolomizes by the Gram method, liquefies gelatine, after growing in whitish colonies, which soon assume a bluish-green color and give off the typical odor of elder. Dressings soiled with the pus also give the peculiar color and odor.
It is a frequent inhabitant of the human skin; the suppurations produced by it arc benign, but it is very resistant and it is very difficult to eliminate it from a wound. It affects especially open granulating wounds (burns) and causes profuse secretion which interferes with the healing process ; it is easily transmitted through the attendant. (Disin fection with formalin!) 5. The Bacterium soli commune (Escherich) (Fig. 107d, Plate 9). This species of bacterium is also of great importance in the surgery of childhood (Moro, Dauntlora). 1 short motile rod which does not produce spores, stained with aniline dyes, deeolorizes by Grain's grows on gelatine in stab cultures in the shape of a wire nail without liquefaction. It is the regular inhabitant of the intestine, Init is also found on the skin and in the clothing. In injuries and disturbances of the intestinal wall it causes suppurations in the abdominal cavity, which differ according to the virulence but are better borne by the child's body than streptococcus infections.