The open method is the only safe means of treating such wounds.  The infected surface may be sponged over with pure carbolic acid, the excess of which is washed off with absolute alcohol, and the wound either drained by tubes or packed with iodoform gauze.  The practice of scraping such surfaces with the sharp spoon, squeezing or even of washing them out with antiseptic lotions, is attended with the risk of further diffusing the organisms in the tissue, and is only to be employed under exceptional circumstances.  Continuous irrigation of infected wounds or their immersion in antiseptic baths is sometimes useful.  The free opening up of the wound is almost immediately followed by a fall in the temperature.  The surrounding inflammation subsides, the discharge of pus lessens, and healing takes place by the formation of granulation tissue—­the so-called “healing by second intention.”

Wound infection may take place from catgut which has not been efficiently prepared.  The local and general reactions may be slight, and, as a rule, do not appear for seven or eight days after the operation, and, it may be, not till after the skin edges have united.  The suppuration is strictly localised to the part of the wound where catgut was employed for stitches or ligatures, and shows little tendency to spread.  The infected part, however, is often long of healing.  The irritation in these cases is probably due to toxins in the catgut and not to bacteria.

When suppuration occurs in connection with buried sutures of unabsorbable materials, such as silk, silkworm gut, or silver wire, it is apt to persist till the foreign material is cast off or removed.

Suppuration may occur in the track of a skin stitch, producing a stitch abscess.  The infection may arise from the material used, especially catgut or silk, or, more frequently perhaps, from the growth of staphylococcus albus from the skin of the patient when this has been imperfectly disinfected.  The formation of pus under these conditions may not be attended with any of the usual signs of suppuration, and beyond some induration around the wound and a slight tenderness on pressure there may be nothing to suggest the presence of an abscess.

Acute Suppuration of a Mucous Membrane.—­When pyogenic organisms gain access to a mucous membrane, such as that of the bladder, urethra, or middle ear, the usual phenomena of acute inflammation and suppuration ensue, followed by the discharge of pus on the free surface.  It would appear that the most marked changes take place in the submucous tissue, causing the covering epithelium in places to die and leave small superficial ulcers, for example in gonorrhoeal urethritis, the cicatricial contraction of the scar subsequently leading to the formation of stricture.  When mucous glands are present in the membrane, the pus is mixed with mucus—­muco-pus.

DIFFUSE CELLULITIS AND DIFFUSE SUPPURATION