(d) Bacteriologic study of the complications of measles during life and at autopsy.
(e) Study of the throat bacteriology of men on duty in the camp, to establish the prevalence of hemolytic streptococci and of B. influenzæ in normal individuals.
The work is further divided into that done at Camp Funston during the latter part of July and throughout August, and that done at Camp Pike during September, October, November and December, 1918.
Studies at Camp Funston.—The work done at Camp Funston is limited strictly to the identification of hemolytic streptococci in the throats of all patients with measles coming into the base hospital at Ft. Riley and to the same study of a group of normal men on duty. During the period of study hemolytic streptococci were identified by throat culture in about 1 in 5 of all the normal men examined. Two instances of otitis media represent the only complications developing in the 112 cases of measles. Cultures from both patients showed staphylococci. The entire absence of streptococcus complications appears the more surprising in view of the fact that the prevalence of hemolytic streptococci among patients under treatment in the ward was for a time as great as that among the normal men. No special hospital management was instituted on the basis of the findings in throat culture. S. hemolyticus carriers remained in the wards and were treated alongside the “clean” cases. The sheet cubicle system was used for bed patients. Face masks were not worn. Convalescent patients were not segregated, and they assisted in the care of the bed patients and in the ward kitchen. After the initial throat culture on admission, the throats were gargled with argyrol and afterwards sprayed with the same solution three times a day. This solution was also employed to relieve the discomfort caused by the conjunctivitis during the acute stage of the disease.
Throat Culture and Identification of Hemolytic Streptococci.—In general the methods for the isolation and identification of hemolytic streptococci as adopted by the Medical Department of the Army were used. All organisms were isolated in pure culture, grown in broth, examined microscopically and subjected to tests for hemolysis, (a 5 per cent suspension of sheep corpuscles being employed), and for bile solubility.
Beef infusion broth and beef infusion agar constituted the two basic media used. They were prepared so that the finished product titrated about 0.3 per cent acid to phenolphthalein.
Broth tubes were carried to the bedside. In swabbing, the attempt was made to produce gagging. This causes the tonsils to protrude from behind the anterior pharyngeal pillars and places a slight tension on the capsule which tends to squeeze material from the crypts. The surfaces of the tonsils thus protruding toward the midline were brushed quickly with a small cotton swab which was lastly touched to the posterior pharyngeal wall and withdrawn so as to avoid touching any other parts. The swab was immediately introduced into a tube of broth, twirled freely under the surface of the liquid and discarded. The material thus washed into the broth was carried to the laboratory and kept in the ice box until plating, which was accomplished with as little delay as possible.
Tubes of melted agar containing 12 c.c. cooled below 45° C., after receiving 0.6 c.c. of sterile defibrinated horse blood, were inoculated with a loopful of this broth. Thorough mixing and pouring into Petri dishes (10 cm. diameter) followed. After cooling, a second loopful was streaked over the surface of one half of the plate. Deep and superficial planting were thus effected on the same plate.
This method was found to be very useful. It can be used with advantage provided one is not called upon to make a great number of cultures when its time consuming factor is a great inconvenience. Another disadvantage is the difficulty of picking single colonies for subculture. In spite of the most careful selection and fishing of a deep colony, subcultures are less likely to be pure than when surface colonies are chosen. By careful regulation of the amount of agar in the tubes, the addition of a measured amount of blood to each enabled one to pour standard blood agar plates. Uniform thorough mixing of the blood is essential so that the plate may present the desired “silky” rather than a “curdled” appearance when viewed by transmitted light.
The plates were incubated eighteen to twenty-four hours when subcultures in broth were made from the hemolytic colonies. After growing these for a similar period the additional tests were carried out as indicated above.