HISTOPATHOLOGIC EXAMINATION OF SUSPECTED TUBERCULOUS SUBMISSIONS VSDL T¥73. Ch D 

 Muhm, R. L., Mote, R. F., and Himes, E. M. "^ 



During FY 1973, field submissions totaling 2,433, were examined by the Diagnostic Histopathology Section, 

 VSDL, for lesions of tuberculosis. Nine hundredand eighty-two of these, approximately 40 percent, were determined 

 by microscopic examination to contain granulomatous lesions with acid-fast bacilli and were reported as 

 "compatible for mycobacteriosis." Seventeen percent were "suggestive of tuberculosis," there were "no significant 

 findings" in 11 percent (mostly from NGL reactors or suspects) and 22 percent as "other" including Actinomycosis, 

 Coccidioidomycosis, neoplasms, and parasites. Fifty-seven percent of the submissions were bovine, 39 percent 

 porcine, 2 percent avian and 2 percent other species. 



There was a large increase in the number of cases submitted as retained pending laboratory results (469 or 19 

 percent in FY 73). This was probably due to the recently implemented regulation concerning cooking or 

 condemning tuberculous carcasses. It is obvious that carcasses cooked or condemned result in a considerable 

 monetary loss for the processor or the producer or both. 



Retained cases are given special treatment so that results can be reported as quickly as possible, usually by 

 phone. This enables prompt disposition of the carcass by the meat inspector. To assure quick and accurate diagnostic 

 results, histopathologic procedures for detecting acid-fast bacilli have been developed, evaluated and modified by our 

 laboratory. These include fluorescent staining procedures for smears and tissue sections. 



An auramine-o acridine orange combination (AOAO) was used to stain representative sections of each piece of 

 tissue. These sections were routinely examined microscopically for acid-fast bacilli and various fungal agents. The 

 AOAO combination has been compared with conventional fuchsin stains for detecting acid-fast bacilli and has 7 

 produced equal or superior results. For this reason the fuchsin stain is used in our laboratory only in certain 

 instances as a special confirmatory preparation. 



The auramine-o stained smear (AO) techniques for the detection of acid-fast bacilli was utilized in all 

 submissions with sufficient gross lesion material to permit this type of preparation. When acid-fast bacilli were 

 detected by the AO smear technique, a diagnosis of "compatible" could be reported in a matter of hours, often on 

 the same day that the submission was received. If no acid-fast organisms were found by the smear technique, 

 additional procedures, taking an average of 1 week's time, were performed before a diagnosis could be reported. 



An examination of FY 73 records indicated that 741 of 982 reports of "compatible with a diagnosis of 

 mycobacteriosis" were detected by the AO smear technique, and comparable results (positive and negative) were 

 obtained in 1,631 of 1,821, or 90 percent, of the cases. This is an important statistic since rapid disposition of 

 carcasses examined only by the AO smear technique could be made with 90 percent confidence. 



In addition to the fluorescent procedures described above representative sections of each tissue were stained 

 with hematoxylin and eosin. These sections were examined microscopically for any characteristic tissue changes. 

 Many special stains were utilized to examine for specific tissue changes or to identify various pathogenic agents. 



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