In the second case, the bacteriological curve drops under the influence of the antiseptic liquid, then, when it has reached a certain level, becomes horizontal. However generous may be the instillations, the microbes no longer diminish in numbers (Fig. 84). Occasionally in the same patient some wounds become completely sterile, whilst others still contain more than fifty microbes per microscope field. The persistence of microbes in the secretions of a wound in spite of the treatment, indicates the presence, in the deeper parts of the wound, of foreign matter, such as shreds of clothing, fragments of projectile, a splinter of bone, a morsel of necrosed tissue; or perhaps a focus of osteitis (Fig. 84). If therefore, after having made sure that the instillation of fluid has been sufficient and continued, and that the conducting tubes are correctly placed, it is noticed that the number of microbes does not lessen, an exploration of the wound should be made, in order to remove the foreign bodies, or scrape the bony surfaces which are keeping up the infection; and then the instillations of Dakin's solution should be continued. Following upon this interference, the number of microbes increases greatly. Afterwards the curve drops, the microbes diminish in number, and may completely disappear (Fig. 84). In short, every time that a wound does not respond to treatment by a progressive diminution in the number of microbes, it is necessary, after having ascertained that the technique of the treatment has been duly observed, to search for foreign bodies or bony lesions. If the source of the reinfection cannot be traced, complete sterilisation becomes impossible.
Fig. 83. - Left leg; wound on internal aspect -; wound on external aspect -. Wounds of the soft parts, suppurating and highly infected. The number of microbes was immense. Sterilisation was obtained suddenly eight days after the beginning of treatment.
Fig. 84. - Deeply infected compound fracture of the tibia becoming sterilised in a partial manner. The reinfection which occurred from the 23rd to the 29th decided us to remove a fragment of sphacelated tendon which had been acting as a foreign body. Sterilisation was obtained in two days.
To resume, in the greater number of wounds, new or old, the number of microbes diminishes rapidly up to the time when each microscope field contains from one to ten. If at this stage, the instillation is practised in an abundant degree, the secretions will soon show only one microbe to two, five, or even ten fields of the microscope. When the curve does not go down in this way, the cause must be looked for and found.
2nd. Characters of the Leucocytes. - From the twelfth hour, the polynuclear leucocytes are seen in more or less abundance in the wound. During the early days the secretions are composed especially of polynuclear cells more or less altered, of a small number of lymphocytes, and of mononuclear cells. The microbes are free, or within the phagocytes. So long as they persist in great numbers in the secretions, the relative proportion of polynuclear and mononuclear cells changes very slightly.
In wounds treated by hypochlorite or chloramines, the free anatomical elements are altered to the same degree as the microbes. Nevertheless, many polynuclear cells enclose microbes which they have devoured before being themselves killed by the hypochlorite. It is therefore probable that the normal phenomena of defence occur as effectually in wounds treated by hypochlorite as in those treated by saline solution. In reality, the hypochlorite does not penetrate into the depths of the tissues. In consequence, in the regions not touched by the antiseptic, phagocytosis goes on as usual. In all the regions affected by the hypochlorite, the leucocytes are destroyed, but inasmuch as the microbes suffer the same fate, no real inconvenience results. Hypochlorite, having a much more energetic action than the fluids of the organism or the polynuclear cells, replaces these agents of defence in their functions. It is ignorance of these elementary principles which has inspired certain French writers with a futile respect for what they call cytophylactic substances.
From the moment when microbes become rare in the secretions, the anatomical elements change their nature. Mononuclear cells increase in number. At the same time we note the appearance of large cells with a single nucleus and fine filaments. It is the indication that the wound is almost aseptic. At the same time, these modifications of the anatomical elements are only of secondary importance in the study of the progress of sterilisation. Although the disappearance of the polynuclear cells and the appearance of large mononuclear cells indicate almost always a marked degree of sterility, the persistence of a large number of polynuclear cells in no way implies that the wound is not becoming sterilised. In fact we frequently see secretions composed of extremely numerous altered, polynuclear cells which, however, contain no microbes. Therefore, to judge the condition of a wound, it is necessary, above all, to base the opinion upon the presence or absence of microorganisms.