Determinants of Infection in the Peritoneal Cavity

The introduction of bacteria into an animal host initiates a series of events which culminates in either the multiplication or destruction of the microbes. In general, the outcome of infections is influenced by cellular and humoral bactericidal factors as well as by the properties of the bacteria which are related to virulence, i.e., toxins, capsules, etc. The interplay between these factors when studied in zitro can often be misleading in terms of the pathogenesis of a given infection in the living animal. The analysis of infections in the intact host is fraught with technical difficulties. Some of the more important of these are: (1) the quantitation of both bacterial and cellular populations, (2) the determination of the rates of bacterial inactivation by humoral and cellular mechanisms, and (3) the transport of bacteria away from the initial injection site with subsequent influences in other parts of the body. Certain of these problems were discussed by Miles' in relation to skin infections, and were considered in the present studies, in terms of a choice of models. Both the intradermal and intravenous routes of infection were considered too complex to permit adequate quantitation and the peritoneal cavity was selected as the site best suited for this purpose. This article will delineate certain of the defense mechanisms operative in the mouse peritoneal cavity and will compare the effectiveness with which they cope with infections produced with both S. aureus and S. albus.