Fig. 75. - Curve representing the sterilisation of the wound in case 522. It shows that the microbes which were in great number on May 31, diminished and practically disappeared by June 17.
FlG. 76. - Right knee. Wound external. Typical curve of sterilisation of a wound of the soft parts. The wound, which contained 40 microbes per microscope field at the time of the first examination, was surgically sterile two days later.
In wounds of the soft parts, microbes disappear from the secretion, generally, from the third to the tenth or twelfth day (Fig. 76). In very irregular wounds, and in those associated with injuries to bone, microbes persist much longer (Figs. 69-75 and 77). The microbes disappear at first from the muscles, and from normal cellular tissue, afterwards from the bony surfaces. The last places in which they are to be found are on fragments of necrosed tissue, and more particularly on tendons and fasciae. As a general rule, after eight, ten, or twelve days, the entire surface of the wound is aseptic, except where there are still necrosed aponeuroses or narrow and deep tracks. In these cases, instillations of hypochlorite have not the power to alter the topography of infection.
Fig. 77. - Compound fracture of tibia. Sterilisation curve of a highly comminuted fracture of the tibia. The first smear was negative because the wound was fresh. The third was equally so because of the presence of blood. Sterilisation the ninth day.
The aseptic cicatrisation of a wound presenting a constant source of reinfection, such as the opening of a sinus unceasingly discharging microbes, can thus be followed. For example, on the surface of a large wound of the abdominal wall there opened a narrow sinus leading down to the fractured ilium.
The surface of the wound was aseptic, whilst the secretions collected at the mouth of the sinus still contained a great number of microbes. The wound therefore showed two quite distinct zones, one aseptic and the other infected. The instillation was continued for several weeks. From time to time reinfection came from the sinus, but it only lasted a few hours, because the septic part of the surface of the granulations became almost immediately sterilised by the solution. The infection was thus kept within narrow bounds at the mouth of the sinus, and the whole of the vast abdominal wound became cicatrised like an aseptic wound.
An analogous limitation of the infection to a very small part of the wound has been observed in many cases. But if, at this period of sterilisation, the instillations are stopped, total reinfection of the wound takes place in a day or two. When the cases whose wounds are almost completely sterilised are transferred to a hospital where a different method is employed, suppuration appears at the end of from two to three days. It is therefore necessary to continue the sterilisation until it is complete. If, on the surface of a wound almost completely aseptic, there still persists the mouth of a sinus leading, either to a bony lesion, or to a fragment of necrosed tissue containing microbes, or to some infected foreign body, reinfection always follows without fail directly the instillation is stopped. On the other hand, careful instillation of the solution into a wound allows it to become cicatrised as rapidly as if it were completely aseptic, even in cases where there exists a region still containing microbes.
It is equally important to examine the surface of the skin surrounding the wound. Completely aseptic wounds may become reinfected after the instillation is stopped, because on the surface of the epithelial border and the adjoining skin are many microbes (Fig. 78). These reinfections of cutaneous origin may greatly retard the progress of cicatrisation (Figs. 79 and 80). An examination of the epithelial scales which cover the skin near the wound, shows that they are loaded with masses of microbes. That is the reason why it is essential to wash with neutral oleate of soda, not only the surface of the wound, but the whole of the region adjoining.
In short, examination of the smears of the secretions collected from different parts of the wound, and of the results of the scrapings of the skin and epithelial margin, shows, from the time of the instillation of the antiseptic treatment, profound modifications in the topography of the infection. Microbes disappear completely from the greater portion of the wound, but still persist in the necrosed tissue, upon irregular bony surfaces, and upon the skin. As soon as the necrosed tissue is dissolved by the hypochlorite, the microbes which were in this nidus disappear also. Those on the skin and osseous surfaces persist longer. It is necessary, therefore, before looking upon a wound as aseptic, to examine those regions which are the last strongholds of infection, and not to stop the treatment before being quite sure that microbes have been eliminated from the whole extent of the wound.