The negative results occurred in seven cases. In three of these (749, 750, 756) B. coli overgrew the cultures from the bronchus, in two also from the lung, and in one, without lung culture, from bronchus and pleural cavity. The mere presence of B. coli, however, did not preclude the isolation of B. influenzæ, as is seen in cases 746, 758, 761 and 765. The finding of B. coli would suggest a post-mortem invasion. The hours after death before the autopsy was done were in these seven cases, ½, 15, 6, 18, 16, 19, 16, respectively. That delay in performing the autopsy, as emphasized by Spooner, Scott and Heath, adds to the difficulty is self-evident, but successful isolations of B. influenzæ have been obtained after even longer periods than in the negative cases (761). In the fourth negative case (763) the bronchus was not cultured. A pneumococcus was grown from the pleural cavity and no growth was obtained from the lung. In the original culture from the pleural cavity influenza-like forms were seen but could not be isolated. In the fifth case (767) a blood culture three days before death gave a growth of pneumococcus mucosus which was also grown from the lung at autopsy. Direct smear from the bronchus showed very few influenza-like forms. Our sixth negative finding was in a case of 20 days’ illness, the patient having had a recurrence (773). Staphylococcus pyogenes aureus, streptococcus viridans and B. xerosis were grown from the bronchus. Only a sarcina form grew from the lung, and a further probable air contamination occurred on the media from the cultures of the pleural cavity. The B. xerosis colonies were confusing, picked as possible B. influenzæ, and, before this was discovered, the overgrowth prevented further attempts to isolate the influenza bacilli. The last unsuccessful case was one with a general infection of a hemolytic streptococcus from an acute otitis media. The streptococcus was isolated from the bronchus, lung, spleen, arm vein and the middle ear at autopsy.
It will be seen that in these seven negative cases technical difficulties prevented the isolation of the B. influenzæ, even if it had been present. I would not, therefore, conclude that the organisms were necessarily absent, but rather that we have failed either to secure material from the focus of infection or on account of the other reasons mentioned.
It is very evident that a variety of secondary organisms very frequently overgrow the field and become numerically predominant. In our first case staphylococcus pyogenes aureus overgrew all the other organisms present in cultures from the lung material. B. influenzæ was, however, seen in the original 24-hour blood agar culture. It required 9 blood agar plates before the organism could be isolated. In another case 10 plates were used for the isolation.
The findings of the bacteria in the lung sections are particularly interesting and instructive. The entire series of cases have not been completely studied, so I am unable to tabulate the findings. In cases 761 and 762 sections of the lung showed influenza-like bacilli to be almost pure in the earlier stages of the process, while in areas with purulent foci pneumococcus-like and other Gram positive cocci were also numerous. In some cases B. influenzæ-like organisms were to be seen in overwhelming numbers. In others they were scarce, while in some nothing resembling B. influenzæ could be found in the sections. Positive cultures were often independent of whether the influenza-like forms were to be seen in smears or sections or not, although they were found in the great majority of the cases. The findings in the direct smears and the bacteriological results make useful material for comparison.
Swabs from the nasopharynx were cultured from 31 individuals; nearly all of these were cases suspected of diphtheria or as carrying the diphtheria bacillus, and no particular effort was made to isolate the B. influenzæ. They were seen in the mixed culture occasionally. In the last eight cases the heated blood agar, ordinary blood agar and Loeffler’s serum were seeded from the throat swabs. B. influenzæ practically overgrew all the other bacteria from seven of these cases on the heated blood agar medium and was isolated without difficulty; all eight showed M. catarrhalis. The two other media gave little or no evidence of the presence of B. influenzæ. As I have said above, our attention was concentrated on the autopsy material. These cultures from the throat were simply made to demonstrate the usefulness of the heated blood agar.
TABLE II
BACTERIA SEEN IN DIRECT SMEARS FROM NASOPHARYNX
| Type of Disease. | Number of Patients. | B. Influenzæ-Like. | Pneumococcus-Like. | M. Catarrhalis-Like. |
|---|---|---|---|---|
| Early | 24 | 14 | 17 | 6 |
| Serious | 13 | 13 | 13 | 9 |
| Convalescent | 11 | 8 | 11 | 6 |
| Total | 48 | 35 | 41 | 21 |
| Percentage of positives | 73 | 86 | 43 |
Direct Smears from Nasopharyngeal Swabs
It is recognized by most of the modern investigators that little reliance can be put on the finding of B. influenzæ-like bacilli in direct smears. The organism is markedly pleomorphic, occurring as extremely small coccoid forms up to threads of various lengths. Notwithstanding these morphological variations the organisms are usually seen as tiny bacilli, and these are considered as the typical form. We carried out a series of microscopical examinations of carefully made smears from the throats of patients with influenza. Particular attention was given to the occurrence of organisms resembling in morphology and staining B. influenzæ, pneumococci and M. catarrhalis. We have divided the cases roughly into three types—early, serious, and convalescent. Table II shows our results. The term B. influenzæ-like was used for the typical morphological picture so often described. Dr. Frost and Mr. Scott carried out this portion of our work and their results are interesting.