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The rate of disappearance of diphtheria bacilli from the throats of individuals infected with the organism Morrison, Margaret. 1922

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TEE RATE OP DISAPPEARANCE OP DIPHTHER | B^IL J^ PROM THE THROATS OP INDIVIDUALS INFECTED WITH THE ORGANISM.BY MARGARET MORRISON. A Thesis submitted for the Degree of Master of Arts in the Department of Bacteriology. UNIVERSITY OF BRITISH COLUMBIA. May, 1922. The Hate of Disappearance o f Diphtheria Bacilli from the Throats of Individaals Infected with the Organism Since the discovery in 188-3, of the Illebs LGeffler bacil-lus as the etiological cause of diphtheria, numerous attempts have been made to ascertain the average persistence of the or-ganism in the infected nose and throat. Man y patients contin-ue to harbor the bacilli after the disappearance of all clini-cal symptom s of the disease, while the average number of diph-theria carriers is about 2$, although a considerable number of these organisms are non-virulent. I n 1890 Sfoherioh stated that the bacilli might be found i n the throats of convalescent patients three days after the disappearance o f the membrane. At this time the question arose as to the necessary length of quarentine. Th e conclusions have been somewhat discouraging, owing to the discrepancy in the results obtained. The reason for this disparity can be readily explained when one studies the various factors which must be taken into consideration. 1. Fo r all statistical purposes the date of onset must necessarily be the date of the first positive diphtheria cul-ture. I n the event of illness for some time prior to consult-ing a physician, with the consequent failure to culture the suspected throat, the knowledge of the presence of the diphth-eria bacilli may be delayed for several days. 2. ;* . swab may be taken by an inexperienced attendant who may fail to reach the infected portion of the naso-pharynx, or crypt of the tonsil, which may harbor th e virulent bacilli. 3. Th e swab may not be properly smeared over the medium, the infected portion of the swab thus failing to come in contact with the surface of the slant. 4. Th e suitableness of the media employed fo r the culti-vation of the bacilli as well as the period of incubation are factors which must be taken into consideration. Insufficien t incubation may result in the growth of atypical forms of diph-theria while prolonged periods of incubation result in an over-growth of secondary organisms. 5. I f antiseptics have been employed previous to the swab-bing of the throat, the subsequent growth of the bacilli on the medium is likely to be retarded. 6. Owin g to an unhealthy condition of the throat with the consequent presence of spore bearers and other contaminating organisms, aside from the diphtheria bacilli, the cultures may be overgrown to the absolute exclusion of the orp-anism in question. The object of this study is to compare the results of an investigation into the average persistence o f the bacilli i n cases examined at the Laboratory of the VancoUMer General Hospital with those obtained elsewhere. The examinations carried out in this laboratory represent cases of clinical diphtheria for diagnosis and release as well as those of suspected carriers. Th e preliminary procedure is as follows: Immediately after the nose and throat swabs have been tak-en, they are inoculated o n the surface of separate tubes of Loef-fler's blood serum and incubate d for a period of sixteen hours at 37° c. Th e necessity for swabbing the nose as well as the throat cannot be overestimated, as it is frequently possible to detect the presence of the diphtheria bacilli in the nasal passages be-fore they are discernable i n the throat. During an outbreak: of diphtheria, especially in the public schools, it becomes necessary to locate the carrier or carriers who in many cases may harbor the virulent bacilli only in the nose. Because of a natural immunity, these organisms may induce no cli-nical symptoms of disease in the host, yet still be the etiolog-ical cause of diphtheria amongst the associates of this carrier. Out of 607 cases examined at this laboratory, 107 or 17.6$ were positive for diphtheria in the nose only. Following the required period of incubation, cultures are smeared and stained by -liert's method. Two solutions are em-ployed for this; an initial stain of toluidin blue followed by a counter stain of iodine, the resulting microscopic picture be-ing a light green rod with dark green metacK-Tomatic granules. The diagnosis in all cases examined at this institution is based solely on morphological characteristics, all atypical forms be-ing disregarded. I n no instance is the virulence of the organ-ism taken into consideration. At the present time the majority of institutions require two or three consecutive negative cultures (taken at twenty-four intervals) before the release of the patient can be regarded as a safe procedure. I t has been found that one negative is fre-quently followed by a positive or by alternating positive and negative cultures. Alternatin g negatives indicate that the bac-illi which had invade d the fauces have decreased i n number alth-ough they are not yet altogether absent, consequently, precaution-ary measures must be taken in order to avoid th e possibility of a false negative. I n the absence of a membrane, one may fail to reach the affected part of the throat harboring the bacilli. Similarly, as mentioned above, if the culture is taken immediate-ly following the use of an antiseptic spray, the chances are that no bacilli will be found. Graham Smith quotes a number of cases where positive cul-tures have been preceded b y negative ones. I n a series of in-vestigations carried on by Hill in 1898, 40^  of those who were eventually released from quarantine with two consecutive neg-atives had, at some time shown alternating positive and negative cultures. H e states that at the Boston City Hospital no t more than 3;o showed positive cultures subsequent to twc consecu -tive negatives at 24 hour intervals. Out of 2,000 cases studied by Rickards, 22$ presented a negative previous to a positive, while in 1901 Cobbett records the same findings in 37fo of the cases examined during the period of quarantine. In an attempt t o secure three consecutive negatives, Graham Smith found 38.3 /9 with premature negatives. I n 112 instances a negative was followed by a single positive,in 66 oases two con-secutive negatives were followed by a positive, while in 17 three consecutive negatives were followed by a positive. Th e above figures therefore demonstrate the fact that in the fore-going ex-aminations 405o of the results obtained were misleading. Results similar to the above have been obtained after an in-vestigation int o the cultures examined at the Vancouver Genera l Hospital, extending over a period o f two years, two successive negatives being required fo r release. Ou t of a series of 238 oases examined 118 or 49.5> yielded premature negatives . O f these, 84 single negatives were followed by one or more positives while 27 cases with two consecutive negatives and 7 with 3 con-secutive negatives were followed by positive cultures. The above statistics emphasize th e necessity of insisting upon at least tw o negatives before the release of the patient and subsequent interminglin g with healthy individuals can be deem-ed advisable. An endeavor was made to ascertain the average length of quar-antine in cases examined at the Hospital laboratory. Th e accom-panying figures represent th e period o f quarantine before two suc-cessive negative cultures were obtained fro m the patient. Thes e cases, 200 in number, include only those yielding two or more pos-itives followed by two consecutive negatives. Ou t of this number the shortest period observed was four days while the longest quarantine was 63 days. 30.5/ 5 had a quarantine of two weeks or less, while 69.5% retained positive cultu. as after a period of two weeks. Th e longest known period o f persistence o f diphther-ia bacilli is that recorded by Prip in 1901 ,  in which positive cultures were obtained fo r 600 days. Varying results have been obtained by other workers who have investigated thi s question. Th e first noteworthy contri-bution to the literature upon this subject was made under the Hew York State Department of Health by Park and Beebe in 1894. Out of 752 cases studied there were negative findings in 325 or 43.25b three days after the disappearance o f the membrane. During 1902 (in a survey of hospital patients) CJraham Smith found the mean duration of persistence of the bacilli to be 28 days. I n a subsequent study in 1904 the duration of virulent bacilli was found to be 36 days in comparison with 15 days for non-virulent bacilli. In 1917 and 1918 Hartley and Martin made an intensive study of the continuance o f the bacilli at the Military Hospital for infections deseases at Roven. Thei r diagnosis was made entire-ly on the morphological characteristics of the bacille Etained by LCeffler's Methylene Blue. Thei r figures show that there is a rapid disappearance of the organism following the first five days of illness, succeeded by a subsequent decrease i n the rate of disappearance. A  minimum of three successive negative cul-tures taken at weekly intervals was required fo r release of the patients. Th e weekly rather than daily periods tended to length-en the time of quarantine, making the results scarcely compara-ble with those of other workers. Thei r figures consequently show an average hospital quarantine o f 45 days, somewhat longer than the periods quoted by other authorities. The observations of Hartley and Uartin, as noted above, ind-icate a rapid decrease in the number of positives after the first five days of illness, the percentage remaining almost stationary up to this time while the patient passes through the acute stages of the disease. Th e rate of disappearance o f the bacilli is giv-en in the following table: Days after onset Observe d positive 5 39 2 10 30 2 15 23 2 20 19 4 25 15 6 30 11 8 35 9 2 40 7 0 45 5 2 50 4 1 In a similar study Graham Smith gives the following figures, In three weeks about 30,J of diphtheria patients are free from Morphologically typical diphtheria bacilli. I n 20> the bacilli persist for four weeks; in 16;a for five weeks; in 11$ for seven weeks; 10o for fifteen weeks. I n exceptional cases they remain in the throat for thirty weeks, although even more prolonged per-lod are recorded. Out of 605 consecutive cases Park and Beebe found the bacilli to disappear in 304 cases, thre days after the dis-appearance of the false membrane, while in 176 cases they per-sisted for seven days; in 64 for twelve days; in 36 for fif-teen days; in 12 for three weeks; in four for four weeks and in 2 for nine weeks. I n occasional instances they remained for months. The following observations were made on the 200 positive cultures which were examined at the Yanconner General Hospital Laboratories, the history in each case being followed unti l two successive negatives were obtained. Days after onset Observe d positives 5 10 15 20 25 30 35 40 45 50 55 As the above figures ind icate 82$ of all 200 192 164 130 87 55 37 23 15 11 5 4 those examined remained positive after 10 days, 65$ after 15 days; 43.5$ after 20 days and 27.5$ after 25 days. In the same 200 cases the following table is of interest as it indicates the number of examinations which it was necess-ary to make before two consecutive negative cultures were obtain-ed. Oat of 200 cases in an effort to obtain two consecutive negatives— * 60 37 20 18 15 17 5 5 11 6 1 3 1 1 1 o u l t a r e s i i r| •i n • i II '1 'T •I '1 M rf n •r were II •< •i ' i n ' i i i II •I n I I •1 II ti examined 4 r l II II •' •t l ' 1 •1 II <t ' I ' l ' l '1 6 6 7 5 9 10 11 12 13 14 15 16 18 27 Conclusions: 1. Available statistic s reveal considerable variation in the rate of disappearance of diphtheria bacilli as well as in the time of quarantine. Th e discrepancy is due to a number of apparently uncontrollable factors as indicated above. 2. Th e fallacy of releasing a patient fro m quarantine after the report of one or two consecutive negatives is noted in the large percentage of alternating positive and negative cultures obtained in the following instances. Hill-- -40 ^ Rickards 22; o Gobbett 37 ^ Graham--* Smith--38.3 > Vanconner General Hospital 49.5f j 3. Th e necessity of swabbing the nose as well as the throat is essential, especially when endeavoring to locate a diph-theria carrier. Ou t of 607 cases examined at the General Hospital 10 7 or 17.6£ wtrt posi t Ira i n th a noaa only . 4* Th a ayerag e lengt h o f quarantine appear s t o be qalt a •arlabia, as lndloate d below . (a) Tha followin g result s hare been obtaine d b y Sraha a Smith:-Quarantine o f 3 weeks i n 30 £ o f cases examine d " " 4 " 2 0 5 » " "  * • f » 5 m  n  1 6 £  n  n  , i n  fj  i t «  n  rf «  i t n (b) Hartley an d Martin i n series o f 302 oaaea found :-302 cases positire afte r 10 day s 232 "  "  "  1 6 • 194 *  *  *  2 0 * • 156 '  *  -  2 6 -118 "  "  " 3 0 " 92 "  •  •  3 6 • 41 *  "  "  5 0 • (o) Th a Vanooziva r General Hospital oa t o f 200 oases found : 192 oases positITS afte r 5  days. 164 *  "  "  1 0 * 130 *  "  •  1 6 " 87 *  * » "  2 0 " 55 "  •  •  2 6 " 3 7 tt  n  i t 3 Q n 23 •  • » "  3 5 " 4 *  "  *  5 5 " 1. II . Y . Lied . Sec . XL7 I ?  385 . 2 . P roc . o f Roy . Soc . o f lie d 1920 , 13,27 7 3 . Bac ter io log y o f Diphther ia — Sraha m Smit h 4 . Prevent iv e l iedicin e o f Hygiene - 21 . J . Rosena u 


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