#Clinical Varieties of Bacillary Gangrene.#—­#Acute infective gangrene# is the form most commonly met with in civil practice.  It may follow such trivial injuries as a pin-prick or a scratch, the signs of acute cellulitis rapidly giving place to those of a spreading gangrene.  Or it may ensue on a severe railway, machinery, or street accident, when lacerated and bruised tissues are contaminated with gross dirt.  Often within a few hours of the injury the whole part rapidly becomes painful, swollen, oedematous, and tense.  The skin is at first glazed, and perhaps paler than normal, but soon assumes a dull red or purplish hue, and bullae form on the surface.  Putrefactive gases may be evolved in the tissues, and their presence is indicated by emphysematous crackling when the part is handled.  The spread of the disease is so rapid that its progress is quite visible from hour to hour, and may be traced by the occurrence of red lines along the course of the lymphatics of the limb.  In the most acute cases the death of the affected part takes place so rapidly that the local changes indicative of gangrene have not time to occur, and the fact that the part is dead may be overlooked.

[Illustration:  FIG. 22.—­Gangrene of Terminal Phalanx of Index-Finger, following cellulitis of hand resulting from a scratch on the palm of the hand.]

Rigors may occur, but the temperature is not necessarily raised—­indeed, it is sometimes subnormal.  The pulse is small, feeble, rapid, and irregular.  Unless amputation is promptly performed, death usually follows within thirty-six or forty-eight hours.  Even early operation does not always avert the fatal issue, because the quantity of toxin absorbed and its extreme virulence are often more than even a robust subject can outlive.

Treatment.—­Every effort must be made to purify all such wounds as are contaminated by earth, street dust, stable refuse, or other forms of gross dirt.  Devitalised and contaminated tissue is removed with the knife or scissors and the wound purified with antiseptics of the chlorine group or with hydrogen peroxide.  If there is a reasonable prospect that infection has been overcome, the wound may be at once sutured, but if this is doubtful it is left open and packed or irrigated.

When acute gangrene has set in no treatment short of amputation is of any avail, and the sooner this is done, the greater is the hope of saving the patient.  The limb must be amputated well beyond the apparent limits of the infected area, and stringent precautions must be taken to avoid discharge from the already gangrenous area reaching the operation wound.  An assistant or nurse, who is to take no other part in the operation, is told off to carry out the preliminary purification, and to hold the limb during the operation.