Standard Blood Agar Plate in the Control of Scarlet Fever * Experience of a Rural Health Unit H. R. O'BRIEN, M.D., F.A.P.H.A. AND R. P. FOWLER Lorain County, District Department of Health, Oberlin, Ohio IN 1929 blood agar plates were introduced by Dr. C. D. Barrett in the work of the Lorain County Health Department in the control of scarlet fever. This study reviews our experience with these plates from January 1, 1931, through August, 1933. In this time we had 339 cases of scarlet fever, 751 suspects, and 16 cases diagnosed as septic sore throat. How we used blood agar plates and our conclusions as to their usefulness is told in this paper. Ours is a district health department in northern Ohio serving a county of 40,000 people scattered over 10 villages and 20 townships in an area of 476 square miles. It is a department of moderate size, with a full-time health officer, 3 nurses, a sanitary officer, a laboratory man, and a clerk. The laboratory man is also the milk inspector. Our laboratory is a small room, 9' x 14', but we make the ordinary bacteriological determinations, except for Wassermanns. When a case of scarlet fever is first seen, a throat culture is taken routinely, from both tonsillar regions if possible. In the laboratory sterile normal saline is poured into the tube, covering the swab. The tube is shaken and set aside. To a tube of ordinary melted *Read before the Laboratory Section of the American Public Health Association at the Sixtysecond Annual Meeting in Indianapolis, Ind., October 12, 1933. agar cooled to 40°-420C. a loop of the saline suspension is added, then 0. 5 c.c. of beef blood (preserved with citrate in the refrigerator). The whole is rolled, then poured into a plate, and incubated. After approximately 18 and 42 hours the plate is examined for the characteristic colonies of the hemolytic streptococcus, beta type. Release culture were taken 18 days after the onset. If positive, still other cultures were taken until negative. We have had no epidemics of scarlet fever, but have shared the general increase which most of Ohio has experienced. The table deals with 103 cases in 1931, 151 in 1932, and 85 in the first 9 months of 1933. This is an annual morbidity rate of 306 per 100,000. Cases have been quarantined on the diagnosis of practising physicians or of the health commissioner. TABLE I Early culture (when first seen) positive 165 First culture negative, a later culture positive .... ..................... 38 First culture negative, later cultures negative .... .................... 53 First culture negative, no release culture shown .... ...................... No early culture taken, later culture positive .... ..................... No early culture taken, later culture 15 17 27 24 negative .......................... No cultures recorded at all ............ Total cases cultured ...... 315  SCARLET FEVER CONTROL Of the 339 positive cases of scarlet fever dealt with, Table I summarizes the results of cultures: Of the 2 71 cases with a culture within a week of onset, 165, or 60.9 per cent, gave a positive culture. Of the 106 negative at first, 38 were later positive. Special effort to reculture early negatives was seldom possible, or more positives would probably have been obtained. Of the 44 who had no early culture, 17 were later positive. Thus of the 315, 220, or 70.2 per cent, were positive at some time. We made some study of the symptoms accompanying scarlet fever. In 188 cases in which report was made, peeling occurred in 161, or 83.0 per cent. Of the cases whose cultures were always negative, 34 peeled, 9 did not. Of those who peeled 104 (66. 7 per cent) had positive cultures at some time, 52 were negative, and 6 had no cultures recorded. In 168 cases there is a definite statement on the question of vomiting. This occurred in 111 cases, or 66. 1 per cent. Most of our cases of scarlet fever were quarantined without reference to the culture, but frequently in doubtful cases we waited for a positive culture and considered it so much additional evidence. It aided when the rash was very faint, or hard to distinguish from other rashes. The culture was uniformly employed when the question of release arose. Ohio now quarantines at least 21 days for scarlet fever. At 18 days after the onset we took a throat culture. If negative, the patient was discharged at 21 days. If positive, the culture was repeated until negative. Usually the throat cleared up rapidly. A continued positive culture was almost invariably associated with enlarged tonsils or enlarged cervical glands. An otitis media would give a positive culture as long as the discharge continued, long after the throat was negative. One high school 871 boy developed a maxillary sinusitis following scarlet fever and a supraorbital abscess. Cultures from the throat became negative, but those from the nose and the incised abscess cavity continued positive until the supraorbital wound healed. We used the cultures quite widely in examining suspects. If scarlet fever appeared in a class in school, the other pupils in the room were examined. Those with sore throats or those arousing suspicion in other ways were cultured. Sometimes a positive culture, added to a suspicious tongue or an almost faded rash, made a diagnosis possible and the child was quarantined. In other cases while the evidence was not conclusive enough to call it definitely scarlet fever, the child was excluded from school as a probable carrier until his throat became clear. We made no study of the virulence of organisms found in the throats of such carriers. In all cultures were made in 751 suspected cases, aside from those quarantined. Of these 181, or 24.1 per cent were positive. Some of those negative might have proved positive on reculturing, but by imposing some degree of restraint on those found positive, we lessened considerably the number of scarlet fever organisms in circulation. It is noteworthy that of the suspects 40 showed some degree of peeling. Of those peeling 15, or 37.5 per cent, had positive throat cultures. Quite possibly we should have quarantined them. By way of comparison, 46. 3 per cent of the quarantined cases who peeled had one or more positive release cultures. Cultures in suspicious cases encountered late in the disease were especially valuable in differential diagnosis. A child with a running ear and a history of a cold and a rash some weeks previously might have had measles or scarlet fever. If the culture showed hemolytic streptococci of the 872 AMERICAN JOURNAL OF PUBLIC HEALTH Cultures were of value in still another throat condition. Severe sore throat is found fairly often, without rash or strawberry tongue, with positive beta type cultures. Almost by definition these are septic sore throat. Sometimes they are clinically mistaken for diphtheria. In such cases we run both a Loeffler slant and a blood agar plate. We would point out that both can be positive in an individual; in one of our cases it took a virulence test to show that it was not diphtheria, but septic sore throat. To a health department doing general milk work it is of special value to know whether a sore throat in the family of a milk dealer is of the septic-sore-throat-scarlet-fever family or not. CONCLUSION beta type, we were inclined to consider it scarlet and isolate. A boy with an infected finger developed an axillary abscess. Later a general punctate eruption appeared. The abscess yielded Streptococcus hemolyticus, beta type. The throat was never sore. Here we had scarlet fever, resulting from an invasion of the bodv by way of the finger instead of the usual avenue, the throat. In 1930 a farmer had a blistered finger, which developed a severe infection of the finger. Culture of the incision showed Streptococcus hemolyticus beta. In 3 days scarlet fever appeared in 1 child, who died. Two other children also had scarlet fever. A baby developed influenza, then empyema, and later a general punctate eruption. The throat never showed hemolytic streptococci, the pleural cavity did so consistently until it healed. The child peeled. A boy treated in a hospital for extensive burns on the leg developed scarlet fever. He was taken home, where he recovered from his scarlet fever. His throat culture was negative and he was released. Three weeks later another child in the household developed scarlet fever. The burned boy's throat was again positive, possibly from the reservoir in the leg. After his throat became negative, he was held until his leg was healed. No further scarlet fever appeared. It is in locating the suspicious or sub-clinical case of scarlet fever, or in differentiating it from confusing diseases that we have found these blood agar plates most valuable. We do not consider them absolute. Much remains to be understood about this organism, its exact relationship to scarlet fever, its occurrence in the ordinary population, etc. But by considering the results of these cultures as part of the total evidence in each case, we are sure that we have been greatly helped. We would recommend the procedure to other small health departments.
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