The Mono-Vacc Tuberculin Skin Test

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SELECTED REPORTS

The Mono-Vacc Tuberculin Skin Test*

while 680 had the tuberculin tine test as well. The three tests were applied by the same trained individual, a tuberculosis control nurse. The Mono-Vacc teste was applied to the right mid forearm, the tine test to the lower right forearm, and the Mantoux to the upper left forearm. All tests were read at 48 hours independently by two physicians on the pulmonary disease service. The Mono-Vacc and tine tests were read and recorded before the Mantoux site was bared to avoid prejudice. The reactions were recorded in terms of millimeters of induration measured in the transverse direction. The Mantoux test was considered positive if a reaction of 10 mm or greater of induration was present. In the initial analysis, the Mono-Voce reaction was considered to be positive if any degree of induration was present. The Mono-Vacc readings were then re-evaluated using 2 mm or greater and 4 mm or greater induration as indicating a positive reaction. The tine test was considered positive if 2 mm or more induration was present at any of the four tine contact points. When different readings were made by the two individuals recording these skin tests, the reaction sites were promptly reexamined and agreement reached as to the degree of reaction present.

Richard B. Byrd, Lt. Colonel, USAF, MC, F.C.C.P.; Douglas R. Cruces), Captaill, USAF, MC;oO Daniel C. Campbell, lr.. Colonel, USAF, MC, F.C.C.P.; and Aurelia A. Kllies, R.N.

The Mono-Vacc tuberculin test was evaluated in a group of 1,423 individuals, the standard for comparison being simultaneously administered Mantoux (pPD, 5 TV). In approximately one-half of these individuals, it was compared with the tine tuberculin test as well. The Mono-Vacc test was found to be acceptable for screening patients for tuberculin sensitivity. It was easily applied, highly acceptable to patients, and produced readily measurable induration. False negative reactions occurred in 1.2 percent which is within the intratest variability of the Mantoux test and thus unlikely to be statistically significant. The primary limiting factor was an 8.4 percent incidence of false positive reactions. However, the ease with which this test is applied would appear to more than compensate for the time spent in retesting with the Mantoux those who prove to be false positives. The tine tuberculin test was found to give similar results, but was more difficult to read and was less acceptable to patients.

RESULTS

Considering the criteria for a positive reaction to be any degree of induration, the Mono-Vacc test, using intermediate strength PPD as the standard (Table 1), was found to have a sensitivity of 98.8 percent and a specificity of 91.6 percent. V sing 2 mm or greater induration as a positive reaction, the sensitivity was found to decrease to 98.4 percent (252/256) and the specificity to increase to 94 percent (1097/1167). With 4 mm or greater induration as the guideline, the sensitivity decreased further to 97.3 percent (249/256) and there was an increase in the specificity to 97.7 percent (1140/ 1167). The results of the tine test when compared to the Mantoux reaction (Table 2) revealed a sensitivity of 98.5 percent and a specificity of 88 percent.

is rapidly becoming one of the Chemoprophylaxis cornerstones of tuberculosis control in this country. An integral part of any chemoprophylactic program is the utilization of the tuberculin test in identifying infected individuals for therapy. However, the search for a reliable tuberculin skin test that is easily applied on a mass survey basis and which is acceptable to the patient continues and prompted us to evaluate the Mono-Vacc test. We also believed it would be of interest to compare the Mono-Vacc with the tine tuberculin test, another screening test presently in wide use. It was decided to use the standard Mantoux, using 5 TV units of purified protein derivative (PPD), as the reference for determining the accuracy of the two screening tests.

°Mono-Vacc tuberculin test material supplied by Lincoln Laboratories, Inc., Decatur, Illinois Table I-Comparison of Mono-Vacc Multiple Puncture

METHODS AND MATERIALS

Technique with Standard PPD 5 TU Mantoux TeBt

The subjects for this study were a group of 1,423 military personnel and dependents who were either hospitalized on our pulmonary disease wards or were outpatients undergoing evaluation by our tuberculosis control unit. All patients had the Mono-Vacc and 5 TU PPD Mantoux tests,

MANTOUX PPD .'5 TU (Induration of 10 mm or greater)

Positive Negative Total

"From the Departments of Pulmonary Disease (Lt Colonel Byrd and Captain Gracey), Thoracic Surgery (Colonel Campbell), and Tuberculosis Control (Miss Knies), USAF Hospital Scott, Scott Air Force Base, Illinois. °°Presently at the Mayo Clinic, Rochester, Minnesota. The views expressed herein are those of the authors and do not necessarily reflect the views of the United States Air Force or the Department of Defense.

MONO-VACC TEST (Any appreciable Induration) Positive

Negative

253 98 .'351

3 1069

1072

=

Total 256 1167 1423

Sensitivity 98.8% (False negatives 1.2%) Specificity = 91.6% (False positives 8.4%)

447

448

BYRD ET AL

Table 2-Comparison of Tine Technique with Standard PPD 5 TV Mantoux Test MANTOUX PPD 5 TU (Induration of 10 or greater)

Positive Negative Total

IllI11

TUBERCULIl\' TIl\'E TEST

(Induration of 2 111111 or greater at any of four points) Positive

Negative

Total

67

1 539 540

68 612 680

73 140

Sensitivity = 98.5% (False negatives 1.5%) Specificity =88% (False positives 12%) DISCUSSION

The Mono-Vacc test is a recently developed method of determining an individual's tuberculin sensitivity. The device used is a disposable ninepoint plastic scarifier mounted on the outer side of a ring which fits on the thumb. A plastic tube containing liquid old tuberculin (OT) is sealed around the points. The tube is removed just before application and the tuberculin solution squeezed onto the points. The material is then applied by pressing the points into the skin of the forearm. The Mono-Vacc test performed well as a screening test in this study. The 1.2 percent incidence of false negatives is probably not significant, as the reproducibility of the Mantoux test itself has been found to be no more than 98 percent.' Three previous studies with the Mono-Vacc test have also shown a similar low incidence of false negatives and it appears very unlikely that one will miss tuberculin positive individuals with this testing technique.':" If a particular tuberculin test is to be satisfactory as a mass screening test, it is imperative that excessive numbers of false negative reactions do not occur, otherwise some cases of tuberculosis may be missed. The tine test in the present study produced a 1.5 percent incidence of false negative reactions. However, there is great variation in the frequency of false negative reactions as reported in previous studies. Capobres et aJ,4 in a study done in a tuberculosis sanitarium, found only 3 percent false negatives. However, two other groups of workers reported false negatives in from 6 to 13 percent of cases. ri.6 These discrepancies are probably related in part to the fact that many of our patients, and those of Capobres, had actual clinical tuberculosis. Since the level of skin sensitivity is generally greater in those with active disease, it is not surprising that a smaller number of false negatives would therefore be seen in these selected groups. One additional factor which may contribute to excess numbers of false negatives is the difficulty in reading the tine test,

since differentiating a 2 mm induration reaction from a smaller reaction may be quite difficult. In any event the high incidence of false negatives from whatever reason in those studies screening population groups without a high incidence of active disease casts serious doubts on the suitability of the tine tuberculin test for screening purposes. The 8.4 percent incidence of false positive reactions found in our study is the obvious primary limiting factor in the Mono-Vacc test. The percentage of false positives can, as noted above, be greatly reduced by raising the minimal criteria for a positive reaction to either 2 or 4 mm of induration. The resulting fall in sensitivity is probably still acceptable. However, we believe one of the virtues of the Mono-Vacc test as a screening procedure is that the technician is not required to quantify the millimeters of induration but only to decide if it is present. Furthermore, the incidence of false negatives might rise and become a limiting factor in a population group which did not include a large number of active cases of tuberculosis with their high levels of skin sensitivity, as did the group of patients studied. Grabau" found that an unacceptable number of false negatives occurred if he used 6 mm of induration as indicative of a positive reaction rather than just the presence of induration in a survey of school children. Furcolow et a)1 experienced the same difficulty in attempting to use 3 mm as the minimal amount of induration for a positive reaction. For these reasons we believe the Mono-Vacc, when used as a screening test, should he considered positive with any degree of induration. The speed and simplicity with which this test is applied would appear to more than compensate for the time spent in retesting with the Mantoux those who prove to be false positives. The tine test in this study showed a 12 percent incidence of false positives. Other investigators also reported excessive numbers of false positives and have suggested that these may be related to previous infections with the atypical mycobacterial strains.P:? Considering the problems experienced by some workers with excessive false negative reactions as discussed above, it would not appear wise to raise the specificity of the tine by requiring a larger reaction for a positive reading. Certain other advantages of the Mono-Vacc test over the tuberculin tine test and the Mantoux were noted which are important when considering a test for screening purposes. The Mono-Vacc reactions were considerably easier to read, with rather discrete margins that could be easily palpated. This advantage has been noted by other investigators.P-" Since these procedures will often he carried out DIS. CHEST, VOL. 56, NO.5, NOVEMBER 1969

449

BREAST CARCINOMA AS CAUSE OF DYSPHAGIA

hy paramedical personnel not experienced in their use, it is important that a test producing an easily measured result be utilized if possible. The Mono-Vacc tuberculin test also proved to be much more acceptahle to our patients than did either the Mantoux or tine technique. There was considerably less pain with application of the MonoVacc test. This feature was particularly of value in the testing of school children. Another serious problem arises with Mantoux tests when given by untrained personnel in that the antigen is frequently given subcutaneously rather than intradcrmally, resulting in false negative reactions. The Mono-Vacc test , by contrast, can he accurately administered even by relatively inexperienced individuals. Despite the occurrence of a considerable number of false positive reactions, we helieve the MonoVacc test to he the hest available screening procedure for tuberculin sensitivity available today. The test can be rapidly and easily applied by untrained personnel with little discomfort to the patient. The reactions induced are quite discrete and the criteria for determining positive reactions very simple. REFERENCES

Fuacoi.ow.

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4

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6 7

WATSOX, K.A .. CHARRO:" , T " xxn LOWE. J. : A comparison of the tin e and Mono-Vacc tests with th e intradermal tuberculin test. Amer. Ret;. ResjJ. tn«. 96: 1009, 1967. STOCKER J.A .: Comparison of a multiple puncture tuberculin test with purified protein derivative, Amer. Rrl'. Resn. Dis.. 96 : 1067, 1967. GRAllAl', A.A. : Comparison of tuberculin testing: between Mono-Vacc a nd ~l antol1X. Dis. Ch est . .5.'5 :411. 1969 . CAPORRES, D .H., TOSH, F.E ., Y.'\TES, I.L., xxn L.,\XGEL UTTIG . H .V. : Experience with tlu- tulx -rculin tin e test ill a sa na tor iu m. J.A.M.A ., 180 :11.'30. 1962. l lot.t.mxv. 'V.H., x xn Rnoxnss . E.R .: A comparison of reactor rates to atypical mycohncterinl antigens in Air Force recruits reacting to the tim- test , Amrr . RrL:. RC·.III. Di.1.. 93:907. 1966. ROSEXTHAL. S.R .: The di sk-tine tuberculin test . I .A .M .A" 177 :4.5.2. 1961. AH1IOXTI. I. .. PARLETT, R.C. , PIERSOX, F .. .vxn .... :"ELl.O. C .: An epiclemlologic comparative stud y in Delaware of the tine and Mnntonx tests . Amrr. Rev . Resp , Dis.. 95 : 81, 1967. ~f.L "

Reprint requests : Col. Byrd, USAF Hospital. Scott AFB , Illinois 62225

Breast Carcinoma as a Cause of Dysphagia* Robert I . Stallone, M .D . and

RCII .WlII

B. Roe , MD .

A case is presented of a 74-year-old woman who had carcinoma of the breast metastatic to the mid-thoracic esophagus 19 years after radical mastectomy. Sympe

r:'rornl he' Dep.a~tlllent of 511 r~ery. ITn~\'('rsi.ty of California School of ~I('dicllle . San Francisco. California.

DIS. CHEST, VOL. 56. NO, 5. NOVEMBER 1969

FIGURE 1. Esophagogram showing mid-esophageal stenosis.

toms of prolonged intermittent dysphagia over a fiveyear period led to esophagoscopy, during which iatrogenic perforation occurred in the mid-esophagus without visualizing obstruction or tumor. Emergency thoracic esophagectomy and esophagogastrostomy with pyloroplasty resulted in a successful outcome. The case represents the longest interval to be reported between removal of a primary tumor and the appearance of a solitary metastasis in the esophagus.

Metastatic tumors to the esophagus usually result from direct extension from contiguous organs such as the larynx , hypopharynx, trachea, bronchus. mediastinum, stomach and thyroid. Metastases from distant organs are rare.' About half of all metastatic tumors of the esophagus present as dysphagia." The following case illustrates a metastatic breast tumor causing prolonged intermittent dysphagia several ypars after the primary tumor had heen removed. CASE REPORT

A 74-year-old white woman complained of intermittent inahility 10 swallow liquids or solid food during the past