Lobar Pneumonia
The frequency with which the confluent lobular consolidation of bronchopneumonia involving whole lobes or parts of lobes follows influenza has emphasized the desirability of distinguishing carefully between lobar and confluent lobular pneumonia. The pulmonary lesion has been designated lobar pneumonia when it exhibited the well-known characters of this lesion, namely, firm consolidation of large parts of lobes, coarse granulation of the cut surface, fibrinous plugs in the bronchi and, on microscopic examination, homogeneous consolidation and fibrinous plugs within the alveoli. With confluent lobular consolidation of bronchopneumonia the consolidated area is in most cases obviously limited by lobule boundaries, and well-defined lobules of consolidation occur elsewhere in the lungs.
Lobar pneumonia occurred in 98 among 241 instances of pneumonia following influenza, namely, in 40.7 per cent of autopsies.
The difficulty of separating lobar and bronchopneumonia following influenza has been increased by the frequent combination of the two lesions in the same individual. There were 34 instances in which lobar and bronchopneumonia occurred together. The anatomic diagnosis of lobar pneumonia was made only when lobes or parts of lobes were firmly consolidated and exhibited the characters of the lesion enumerated above; in several instances, in which there was some doubt concerning the nature of the lesion, microscopic examination was decisive. The associated bronchopneumonic lesions represented all the types which have been associated with influenza. In the group of 34 cases of coexisting lobar and bronchopneumonia, lobular consolidation occurred 10 times, peribronchiolar consolidation 14 times (recognized in all but 4 instances by microscopic examination), hemorrhagic peribronchiolar consolidation 9 times, peribronchial pneumonia 4 times. The intimate relation of these lesions to changes in the bronchi is well shown by the frequent presence of purulent bronchitis. The associated lesions of the bronchi in these cases were as follows: purulent bronchitis in 23 instances; peribronchial hemorrhage in 6; bronchiectasis in 11. The frequency of purulent bronchitis and other bronchial lesions in association with coexisting lobar and bronchopneumonia is in sharp contrast with the occurrence of these lesions in association with lobar pneumonia alone; with 69 instances of lobar pneumonia alone purulent bronchitis occurred 17 times and bronchiectasis once.
Lobar pneumonia following influenza passes through the usual stages of red and gray hepatization. Red hepatization was found 16 times, combined red and gray hepatization 28 times, and gray hepatization 20 times. The average duration of pneumonia with red hepatization was 3.7 days, with combined red and gray hepatization 5.1 days and with gray hepatization 7.5 days. These figures, it will be shown later, have some importance in relation to the stage at which hemolytic streptococcus infects lungs the site of lobar pneumonia.
Bacteriology of Lobar Pneumonia.—Table XXX is compiled with the purpose of determining the bacteriology of the bronchi, lungs and heart’s blood in autopsies performed on individuals with lobar pneumonia. In some instances bacteriologic examination of one or other of these organs was omitted; the percentage incidence is an index of the presence of pneumococci, hemolytic streptococci, staphylococci or B. influenzæ in the bronchi, lungs or heart’s blood and measures the invasive power of these microorganisms during the course of lobar pneumonia following influenza.
| Table XXX | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| NO. OF CULTURES | PNEUMOCOCCI | HEMOLYTIC STREPTOCOCCI | STAPHYLOCOCCI | B. INFLUENZÆ | |||||
| NO. POSITIVE | PER CENT POSITIVE | NO. POSITIVE | PER CENT POSITIVE | NO. POSITIVE | PER CENT POSITIVE | NO. POSITIVE | PER CENT POSITIVE | ||
| Bronchus | 44 | 56.9 | 14 | 31.8 | 22 | 37 | 84.1 | 96 | 79.3 |
| Lung | 53 | 77.3 | 13 | 24.5 | 8 | 26 | 49.1 | 70 | 45.7 |
| Blood | 87 | 65.5 | 11 | 12.6 | 1 | 0.5 | |||
Pneumococci, the recognized cause of lobar pneumonia, were found in the lungs in 73.3 per cent of autopsies; failure to find the microorganism in all instances is doubtless the result of its disappearance from the lung, which, it is well known, occurs not infrequently particularly during the later stages of the disease. In 65.5 per cent of instances of fatal lobar pneumonia pneumococci have entered the heart’s blood.
Hemolytic streptococci unlike pneumococci were found more frequently in the bronchi than in the lungs; this microorganism which exhibits little tendency to disappear, once it has established itself within the body, found entrance into the bronchi in 31.8 per cent of instances of lobar pneumonia and in 24.5 per cent entered the lungs. Its invasive power is further illustrated by its penetration into the heart’s blood approximately in half this proportion of autopsies.
Staphylococci enter the bronchi in many instances (50 per cent), but relatively seldom (15.1 per cent) invade the lung and rarely if ever penetrate into the blood.
The high incidence, namely, 84.1 per cent, of B. influenzæ in the bronchi is particularly noteworthy; it exceeds that of pneumococci, the well-recognized cause of lobar pneumonia, within the lung. It is found much less frequently within consolidated lung tissue and shows no tendency to invade the heart’s blood. B. influenzæ finds the most favorable conditions for its multiplication within the bronchi.
In view of the frequent occurrence of coexisting lobar and bronchopneumonia it has appeared desirable to determine how far the existence of obvious bronchopneumonia modifies the bacteriology of lobar pneumonia. In Table XXXI the incidence of pneumococci, hemolytic streptococci, staphylococci and B. influenzæ after death with lobar pneumonia on the one hand is compared with their incidence after combined lobar and bronchopneumonia on the other.
Pneumococci are found in the lung more frequently with lobar than with combined lobar and bronchopneumonia. The incidence of hemolytic streptococci and of staphylococci in the lung is on the contrary higher when bronchopneumonia is associated with lobar pneumonia. It is not improbable that these microorganisms have a part in the production of associated bronchopneumonia. The frequency with which microorganisms invade the blood is almost identical in the two groups.
| Table XXXI | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| With Lobar Pneumonia Alone | |||||||||
| NO. OF CULTURES | PNEUMOCOCCI | HEMOLYTIC STREPTOCOCCI | STAPHYLOCOCCI | B. INFLUENZÆ | |||||
| NO. POSITIVE | PER CENT POSITIVE | NO. POSITIVE | PER CENT POSITIVE | NO. POSITIVE | PER CENT POSITIVE | NO. POSITIVE | PER CENT POSITIVE | ||
| Bronchus | 30 | 20 | 66.6 | 9 | 30 | 15 | 50 | 26 | 86.7 |
| Lung | 34 | 29 | 85.2 | 7 | 20.6 | 3 | 8.8 | 18 | 52.9 |
| Blood | 54 | 36 | 66.7 | 7 | 13 | ||||
| With Combined Lobar and Bronchopneumonia | |||||||||
| NO. OF CULTURES | PNEUMOCOCCI | HEMOLYTIC STREPTOCOCCI | STAPHYLOCOCCI | B. INFLUENZÆ | |||||
| NO. POSITIVE | PER CENT POSITIVE | NO. POSITIVE | PER CENT POSITIVE | NO. POSITIVE | PER CENT POSITIVE | NO. POSITIVE | PER CENT POSITIVE | ||
| Bronchus | 14 | 9 | 64.3 | 5 | 34.3 | 7 | 50 | 11 | 78.6 |
| Lung | 19 | 12 | 63.2 | 6 | 31.6 | 5 | 26.3 | 8 | 42.1 |
| Blood | 33 | 21 | 63.1 | 4 | 12.1 | ||||
The relative frequency with which different types of pneumococci produce lobar pneumonia under the conditions existing when Camp Pike was attacked by an epidemic of influenza is indicated by Table XXXII in which instances of lobar pneumonia alone and of combined lobar and bronchopneumonia are listed separately.
Pneumococcus I and II, which are found approximately in two-thirds of instances of lobar pneumonia occurring in cities, have an insignificant part in the production of these lesions. Pneumococcus IV and atypical Pneumococcus II, which are commonly found in the mouth, are the predominant cause of these lesions, and with Pneumococcus III, also an inhabitant of the mouths of normal individuals, have been the cause of two-thirds of all instances of lobar pneumonia observed in this camp.
| Table XXXII | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| With Lobar Pneumonia | |||||||||||
| NO. OF CULTURES | PNEUMOCOCCUS I | PNEUMOCOCCUS II | PNEUMOCOCCUS II (Atyp.) | PNEUMOCOCCUS III | PNEUMOCOCCUS IV | ||||||
| NO. POSITIVE | PER CENT POSITIVE | NO. POSITIVE | PER CENT POSITIVE | NO. POSITIVE | PER CENT POSITIVE | NO. POSITIVE | PER CENT POSITIVE | NO. POSITIVE | PER CENT POSITIVE | ||
| Bronchus | 30 | 1 | 3.3 | 1 | 3.3 | 4 | 13.3 | 4 | 13.3 | 10 | 33.3 |
| Lung | 34 | 1 | 2.9 | 2 | 5.9 | 9 | 26.5 | 6 | 17.6 | 11 | 32.4 |
| Blood | 54 | 2 | 3.7 | 2 | 3.7 | 12 | 22.2 | 3 | 5.6 | 17 | 31.5 |
| With Combined Lobar and Bronchopneumonia | |||||||||||
| NO. OF CULTURES | PNEUMOCOCCUS I | PNEUMOCOCCUS II | PNEUMOCOCCUS II (Atyp.) | PNEUMOCOCCUS III | PNEUMOCOCCUS IV | ||||||
| NO. POSITIVE | PER CENT POSITIVE | NO. POSITIVE | PER CENT POSITIVE | NO. POSITIVE | PER CENT POSITIVE | NO. POSITIVE | PER CENT POSITIVE | NO. POSITIVE | PER CENT POSITIVE | ||
| Bronchus | 14 | 2 | 14.3 | 1 | 7.1 | 3 | 21.4 | 3 | 21.4 | ||
| Lung | 19 | 1 | 5.3 | 5 | 26.3 | 6 | 31.6 | ||||
| Blood | 33 | 2 | 6.1 | 3 | 9.1 | 4 | 12.1 | 12 | 36.4 | ||
There is no noteworthy difference in the occurrence of these types of pneumococci among instances of lobar pneumonia, on the one hand, and of combined lobar and bronchopneumonia, on the other. Different types exhibit no noteworthy differences in their ability to penetrate into lungs and blood.
Hemolytic Streptococcus with Lobar Pneumonia.—There can be no doubt that the concurrent infection with microorganisms other than pneumococcus modifies the progress of lobar pneumonia. With lobar pneumonia alone hemolytic streptococci have entered the bronchi in 30 per cent of instances and have penetrated into the lungs in 20.6 per cent; with associated lobar and bronchopneumonia the same microorganism has entered the bronchi in 34.3 per cent of instances and invaded the lung in 31.6 per cent. Hemolytic streptococci are the only microorganisms other than pneumococci which, in association with lobar pneumonia, have found their way from the lungs to the blood stream; more than one-third of all instances of lobar pneumonia in which hemolytic streptococci find entrance into the bronchi die with streptococcus septicemia.
Separation of instances of lobar pneumonia into groups on the basis of the occurrence of red or gray hepatization shows that infection with hemolytic streptococcus is more likely to occur during the early stages of the disease. The average duration of lobar pneumonia with red hepatization has been 3.7 days, with red and gray hepatization, 5.1 days, and with gray hepatization, 7.5 days. Infection with hemolytic streptococcus has occurred in association with red or gray hepatization as shown in Table XXXIII.
| Table XXXIII | |||
|---|---|---|---|
| NO. OF AUTOPSIES | NO. WITH HEMOLYTIC STREPTOCOCCUS | PER CENT WITH HEMOLYTIC STREPTOCOCCUS | |
| Lobar pneumonia with red hepatization | 16 | 6 | 37.5 |
| Lobar pneumonia with red and gray hepatization | 28 | 6 | 21.4 |
| Lobar pneumonia with gray hepatization | 20 | 1 | 5.0 |
Notwithstanding the longer duration of the disease and consequent prolongation of exposure to infection, lobar pneumonia, which has reached the stage of gray hepatization, has shown the smallest incidence of infection with hemolytic streptococci. In the stage of gray hepatization there is diminished susceptibility to secondary infection with this microorganism.
Characteristic histologic changes have been found in the lungs of those who have died with lobar pneumonia followed by invasion of lungs and blood by hemolytic streptococci (e. g., Autopsies 273, 430), but with no evidence of suppuration found at autopsy. Within the pneumonic lung occur patches of necrosis implicating both exuded cells and alveolar walls; in some places nuclei have disappeared; elsewhere nuclear fragments are abundant. In these patches of necrosis Gram-positive streptococci in short chains occur in immense number. In some instances (e. g., Autopsies 273, 346, 479) interlobular septa are very edematous and often contain a network of fibrin; lymphatics are dilated and contain polynuclear leucocytes in abundance. Streptococci are found within these lymphatics. The histologic changes which have been described represent the earliest stages of abscess formation and interstitial suppuration, lesions almost invariably caused by hemolytic streptococci.
Chart 2.—Showing the relation of (a) date of onset of cases in which autopsy demonstrated lobar pneumonia, indicated by upper continuous line with single hatch, and of (b) date of death of these cases, indicated by lower continuous line with double hatch to (c) the occurrence of influenza, indicated by the broken line, and to (d) the total number of fatal cases of pneumonia, indicated by the broken dotted line. Each case of fatal pneumonia is indicated by one division of the scale as numbered on the left of the chart; cases of influenza are indicated by the numbers on the right of the chart.
Relation of Lobar Pneumonia to Influenza.—Some writers have suggested that lobar pneumonia, heretofore observed during the course of epidemics of influenza, is an independent disease with no relation to influenza, both diseases being referable perhaps to similar meteorologic or other conditions. Chart 2, which shows by weeks from September 1 to October 31 the relation of deaths from lobar pneumonia (indicated by double hatch) to deaths from all forms of pneumonia, disproves this suggestion. The two curves follow parallel courses; that representing lobar pneumonia reaches a maximum approximately one week after the outbreak of influenza had reached its height. Lobar pneumonia, like other forms of pneumonia, was secondary to influenza. When a chart is plotted to represent the dates of onset of fatal cases of lobar pneumonia (indicated by single hatch in Chart 2), it becomes evident that the greatest number of these cases of pneumonia had their onset at the beginning of the influenza epidemic, approximately one week before it reached its height. Fatal lobar pneumonia developed less frequently in the latter part of the epidemic; to obtain an explanation of this relation it is necessary to chart separately cases of lobar pneumonia with secondary streptococcus infection, for we have already learned that streptococcus infection was the predominant cause of death in the early period of the influenza epidemic. Exclusion of these instances of secondary streptococcus infection makes no noteworthy change in the character of the chart. Fatal lobar pneumonia, like all forms of fatal pneumonia (p. [140]), was more frequent in the first half than in the second half of the epidemic. This difference is referable either to greater virulence of the virus of influenza or to the greater susceptibility of those first selected by the disease or, as more probable, to conditions such as crowding together of patients with influenza, favoring the transmission of microorganisms which cause pneumonia.