The Site of Predilection in Cross-infection from the Right to the Left Lung

Abstract

INFECTIONS of the right lung which result in destruction of pulmonary tissue not infrequently give rise to infection in the opposite lung. This we have termed “cross-infection.” It is an autogenous infection due, apparently, to the inhalation of infectious exudate and detritus (Fig. 1). Although cross-infection of this type may occur in any part of the left lung, there is such a tendency for it to occur in a local region comprising about a fourth of the lung midway between the apex and the base, that this can be considered the site of predilection. In roentgenograms made in the usual postero-anterior projection this area lies between the second and fifth ribs. This entire area may be originally involved but usually early there will be a limited focus somewhere in this quadrant (Fig. 2). When the destructive lesion involves particularly the right upper lobe one would expect aspiration infection of the right lower lobe to precede cross-infection, as the bronchus to the right lower lobe is an almost direct continuation of the trachea. This type of secondary infection does occur quite frequently, usually in association with cross-infection; but the infection is largely limited to the peribronchial tissues and those alveoli adjoining the bronchi. The secondary infection in this region does not as a rule involve the peripheral parenchyma to the extent that the parenchyma is involved in cross-infection. In some cases, however, secondary infection of the lower lobe is more extensive and of greater importance than cross-infection of the left lung (Figs. 3, 4, 5, 6, and 7). Cross-infection has been observed most frequently in the presence of a breaking down or cavitation of a caseous tuberculous lesion. This one would expect, as tuberculosis is the most common cause of pulmonary destruction (Fig. 8). Case I.—The following case of caseous pneumonia of the right lower lobe illustrates the progressive involvement of the right upper lobe and the early involvement of the left lung by cross-infection. 4-10-29: Two weeks after an abdominal operation, there is consolidation of the right lower lobe—caseous pneumonia. There is also a diffuse infiltration in the right upper lobe. The left lung is apparently clear (Fig. 9). 4-12-29: Relatively little change is noted except a small area of infiltration at the anterior end of the second rib on the left side. This was not noticed when the films were originally studied. 4-17-29: The area of cross-infection is slightly larger. It was still unrecognized (Fig. 10). 6-3-29: There is considerable increase in the area of cross-infection, and also in the infiltration of the right upper lobe (Fig. 11). 7-11-29: Extensive involvement of the left lung and the right upper lobe (Fig. 12). Case II.—This case illustrates the progressive involvement in a fatal case of pneumonic tuberculosis. The patient was a 15-year-old Negress, admitted to the Fifth Avenue Hospital as a case of pulmonary abscess.