The bacteriology of these cases presents no constant feature. Invasion of the blood by S. hemolyticus has been present in a large proportion of cultures, namely, in 5 of 7 (71.4 per cent). In one of the 2 instances in which hemolytic streptococci have been found, neither in the blood nor lungs, Pneumococcus III has been found in the blood and S. viridans in the lungs and bronchus; in the other, S. aureus has been found in the lung and bronchus. Staphylococci have been found frequently in the bronchi (60 per cent) and in the lungs (50 per cent). B. influenzæ has been present in the bronchi in the usual proportion of instances (80 per cent). The lesion has occurred in the presence of B. influenzæ combined with streptococci or staphylococci.
| Table LIII | ||||
|---|---|---|---|---|
| AUTOPSY | DURATION OF ILLNESS | BLOOD | LUNGS | BRONCHUS |
| 420 | 11 days | S. hem. | S. hem., B. inf., S. aur. | |
| 402 | 14 days | Pneum. IV, S.hem. | ||
| 370 | 17 days | S. aur. | S. aur., Pneum. IV, B. inf. | |
| 457 | 17+ days | Pneum. IV, B. inf. | ||
| 421 | 19 days | S. hem. | Pneum. IV, S. hem. | |
| 445 | 27 days | S. hem. | Pneum. IV, S. aur. | S. aur. |
| 473 | 28+ days | Pneum. III | S. vir. | B. inf., S. vir., staph., M. catarr. |
| 499 | 36 days | S. hem. | S. hem. B. inf. | |
Thrombosis of lymphatics in the wall of bronchi adjacent to blood vessels and in interlobular septa occurs, and occasionally organization of the fibrinous plug within the lymphatic is in progress (Autopsies 283, 425 and 463). Fibroblasts and capillaries penetrate from the wall of the lymphatic into a mass of hyaline fibrin which fills the lumen.
Unresolved Bronchopneumonia.—The most common type of pneumonic lesion following influenza is characterized by acute inflammation of the alveoli immediately adjacent to the bronchioles and the lesion is associated in many instances with hemorrhage or edema. If this lesion persists unresolved during several weeks, evidences of chronic inflammation are found. Peribronchial, perivascular and interlobular connective tissue is thickened and richly infiltrated with lymphoid and plasma cells, large mononuclear cells and many young fibroblasts. Interalveolar septa adjacent to the walls of bronchi and between alveoli surrounding inflamed bronchioles are implicated in the process. Interstitial changes characterize the lesion only in its late stage. It appears undesirable to give the name “interstitial pneumonia” to the early stage of a lesion which begins and in most instances terminates as an acute relatively superficial inflammation of the bronchi, bronchioles and peribronchiolar alveoli.
Chronic bronchopneumonia is often overlooked at autopsy because newly formed connective tissue is not present in sufficient quantity to attract attention (Fig. 26). When the lesion is advanced conspicuous gray white patches of fibrous tissue may be seen about the bronchi (Autopsy 487; Fig. 27) and interlobular septa may be obviously thickened (Autopsy 472). The most distinctive feature of the lungs is the presence of small, firm, gray or yellowish gray nodules of consolidation which resemble miliary tubercles. They represent the peribronchiolar patches of bronchopneumonia present during the acute stage and have assumed the well-defined outline and firm consistence of tubercles because polynuclear leucocytes and red blood corpuscles have in large part disappeared, interstitial tissue is increased, and exudate is in process of organization. These nodules are grouped in clusters about the small bronchi.
With unresolved bronchopneumonia the lungs are very voluminous and fail to collapse after they are removed from the chest and in some instances even after incision. The air containing tissue is usually dry. In our autopsies the lungs have been pink in color and often free from coal pigment, because those suffering with pneumonia have been in considerable part men from rural districts. Thick mucopurulent material exudes from the small bronchi which have been cut across; purulent bronchitis has been present in 20 of 21 instances of chronic bronchopneumonia. Bronchiectasis has been present in 13 instances; dilatation is often advanced, so that throughout the lungs are found bronchi with no cartilage distended to a diameter of 0.5 cm. In addition to the firm peribronchiolar tubercle-like nodules of consolidation there are scattered patches of gray lobular or confluent lobular consolidation. Yellowish nodules, grouped about bronchi and resembling those found elsewhere in air containing tissue, are occasionally seen scattered upon the cut surface of a patch of gray, confluent lobular consolidation (Autopsies 421, 423, 431).
Fig. 26.—Unresolved bronchopneumonia with tubercle-like nodules of peribronchiolar consolidation best seen in lower lobe; bronchiectasis. Autopsy 425.
Microscopic examination demonstrates the presence of those changes which have been described in association with chronic bronchitis and bronchiectasis. There is abundant new formation of fibrous tissue about the bronchi of small and medium size, thickening of adjacent interalveolar walls and incorporation of alveoli into the thickened bronchial wall (Figs. 27, 28, 30, and 31). In half of the instances of chronic bronchopneumonia there has been peribronchial fibrinous pneumonia, and organization of fibrin within the alveoli is usually well advanced. In one instance (Autopsy 487; Figs. 27 and 28) after an illness of fifty-five days this process has resulted in the formation of conspicuous patches of firm, grayish white fibrous tissue surrounding dilated bronchi. Organization of fibrinous exudate within the lung has not been limited to the alveoli but has occurred in the bronchioles as well. Organizing bronchiolitis has been present in 5 instances (Autopsies 370, 402, 457 and 473).
Increase of fibrous tissue occurs about the blood vessels and in the septa between the lobules, which are infiltrated with mononuclear wandering cells and fibroblasts. Dilatation and thrombosis of the lymphatic vessels have occurred in both situations, and in 3 instances (Autopsies 283, 425 and 463) organization of these fibrinous thrombi has occurred.