#Means taken to Prevent Infection of Wounds.#—­The avenues by which infective agents may gain access to surgical wounds are so numerous and so wide, that it requires the greatest care and the most watchful attention on the part of the surgeon to guard them all.  It is only by constant practice and patient attention to technical details in the operating room and at the bedside, that the carrying out of surgical manipulations in such a way as to avoid bacterial infection will become an instinctive act and a second nature.  It is only possible here to indicate the chief directions in which danger lies, and to describe the means most generally adopted to avoid it.

To prevent infection, it is essential that everything which comes into contact with a wound should be sterilised or disinfected, and to ensure the best results it is necessary that the efficiency of our methods of sterilisation should be periodically tested.  The two chief agencies at our disposal are heat and chemical antiseptics.

#Sterilisation by Heat.#—­The most reliable, and at the same time the most convenient and generally applicable, means of sterilisation is by heat.  All bacteria and spores are completely destroyed by being subjected for fifteen minutes to saturated circulating steam at a temperature of 130 to 145 C. (= 266 to 293 F.).  The articles to be sterilised are enclosed in a perforated tin casket, which is placed in a specially constructed steriliser, such as that of Schimmelbusch.  This apparatus is so arranged that the steam circulates under a pressure of from two to three atmospheres, and permeates everything contained in it.  Objects so sterilised are dry when removed from the steriliser.  This method is specially suitable for appliances which are not damaged by steam, such, for example, as gauze swabs, towels, aprons, gloves, and metal instruments; it is essential that the efficiency of the steriliser be tested from time to time by a self-registering thermometer or other means.

The best substitute for circulating steam is boiling.  The articles are placed in a “fish-kettle steriliser” and boiled for fifteen minutes in a 1 per cent. solution of washing soda.

To prevent contamination of objects that have been sterilised they must on no account be touched by any one whose hands have not been disinfected and protected by sterilised gloves.

#Sterilisation by Chemical Agents.#—­For the purification of the skin of the patient, the hands of the surgeon, and knives and other instruments that are damaged by heat, recourse must be had to chemical agents.  These, however, are less reliable than heat, and are open to certain other objections.