E i k e n e l l a c o r r o d e n s is a facultative,

anaerobic gram-negative bacillus of uncertain pathogenicity in man that has not previously been reported in the endodontic literature. Henriksen l described three strains of anaerobic gram-negative bacilli that shared unusual properties of colonial growth on solid media. These properties included the tendency to start growth in the form of a depression rather than in a raised colony and to produce a continuous, spreading growth with concentric zones of spread. Holm e named these organisms "the corroding bacillus" because the colonies resembled "small, mat, corroded patches on the surface of the blood agar." Eiken 3 further described the colonial growth as well as the biochemical properties of the organisms. Eiken was the first to propose the term B a c t e r o i d e s c o r r o d e n s because of the characteristic colonial morphology. He characterized 21 different strains from abscesses, soft tissue infections, and from sputum. ~ Three of Eiken's strains were microaerophilic, while the others were obligate anaerobes; all grew slowly. Henriksen 4,~ confirmed Eiken's findings. Jackson and associates 6 studied B c o r r o d e n s to see if it could not be classified in two groups, a facultative aerobic corroding bacilli and an obligate anaerobic corroding bacilli. Biochemical differences between those two groups were noted. There were specific differences in immunologic specificity as well as differences in the guanine and cytosine content. E c o r r o d e n s is now reserved for classifi28

cation of facultative anaerobes, and B corrodens is reserved for classification of obligate anaerobes. 6,r King s characterized 118 strains with properties similar to those described by Eiken, 3 except that they were either capnophilic or microaerophilic. These organisms were called HB-1 strains of King. Riley9 found that the HB-1 strains of King were identical to the E c o r r o d e n s of Jackson and his associates. 6 Information relative to the ecology, pathogenicity, and clinical importance of E c o r r o d e n s is sparse. TM E corrodens has been isolated from blood cultures taken after tooth extraction. a1,12 E c o r r o d e n s has also been the sole infecting agent in some patients with meningitis, subdural empyema, osteomyelitis, and endocarditis. Report of C a s e A 25-year-old white man was seen because of tenderness when chewing. Radiographs showed a radiolucency periapical to the maxillary left central incisor. Since the tooth was restored with a porcelain jacket crown, a decision was made to perform a test cavity. The tooth was isolated with a rubber dam, the field was scrubbed with M e t a p h e n - a n d then with 92% isopropyl alcohol, and allowed to dry. All long-handled instruments were flamed twice before contact with any part of the field. A n appropriate bur was selected to gain access to the root canal system. The pulp was necrotic. A total of five prepackaged and presterilized paper points was used to sample the exudate of the root canal

system. The paper points were placed in a holding medium (Stuart's Transport Medium),* and the sample was submitted to Clinical Diagnostics Laboratory for routine culture and antibiotic sensitivity testing. Serial cleaning and shaping, as described by Schilder, 13 was used to debride the root canal system of the tooth; Cresatin was used as the intracanal medicament. The results of the culture and sensitivity testing were obtained by telephone 72 hours after the sample was submitted. A written report of the results was received seven days after the sample was submitted for testing. The original report indicated alpha-hemolytic streptococcus and oxidase-positive, gram-negative rod. The sensitivity pattern reported at this time is shown in Table 1. The patient was seen again seven days later; he had not experienced any discomfort since his last visit. The root canal system was dry, and the tooth was obturated by means of the warm gutta-percha technique as described by Schilder. ~4 Biochemical assay was used to iden-

Table 1 9 Antibiotic sensitivity pattern. Antibiotic



Ampicillin Carbenicillin Cephalothin Chloramphenicol Colistin Dicloxacillin Erythromycin Gentamicin Kanamycin Lincomycin Methicillin Neomycin Penicillin Polymyxin B Triple Sulfas Tetracycline




S -S



*Key: l=alpha-hemolytic streptococcus; 2 = Eikenella corrodens; S ---Sensitive; R = resistant.


t VOL 2, NO 1, JANUARY 1976

Table 2 9 Biochemical assay of Eikenolla corrodens.




ology stain i~talase tklase i~ility ~atin hydrolysis tmus milk jtrate (Simmons')

the identification being ( H B - I ) E corrodens.

small rods Discussion


itole ~a hydrolysis trates iple sugar iron agar lant ~Butt



t-I~ ~culin hyrolysis ~nylpyruvic acid ~eller's lysine decarboxylase ~eller's axginine dihydrolase medium open Cucose closed ~nolysis I[r t~MacConkey agar [~Salmonella-Shigella agar [Centrimide agar 25 C 35 C 42 C i~Aerobically .~CO2 A.nerobically 'A:I: culture media 31ucose Xylose Lactose Maltose

.~oHMI Sucr~ nnitoI acetate paper for S detection th around X disc

+ -

Zeldow has said that "the evidence strongly supports the wisdom of routine antibiotic-sensitivity testing to alleviate the empirical selection of a drug in the event of an acute exacerbation during endodontic treatment. ''1~ A l t h o u g h this case did not require the use of antibiotic therapy, it was shown through the use of routine culture and antibiotic sensitivity tests that some of the m o r e favored antibiotics would not have been effective. In this particular case, the organism in question has been reported to have a 3 0 % mortality. 1G T h e significance of the mortality for this organism as applied to root canal therapy is not known at this time. SummarF

N gr* N gr* N gr* grt grt grt grt


no growth growth CTA = cystine-trypticase agar

tify the oxidase-positive, gram-negative rod (Table 2). Thc assay was verified by the Los Angeles Public Health Department,

A previously unreported organism, E corrodens, was isolated and identi-

fied through the use of routine culture and sensitivity testing. T h e culture sample was placed in Stuart's Transport M e d i u m for submission to the laboratory. This particular organism can be identified only by means of biochemical assay. Infections involving this organism have been reported to have a mortality as high as 3 0 % . The significance of this death rate as applied to root canal therapy is unknown. The author thanks Pamela Munson, MTM, for providing both the original biochemical assay and the diagnosis. * Clincial Diagnostics, Inc., 9210 Sunset Blvd, Los Angeles, Calif 90069. Dr. Goodman is assistant clinical professor of endodontics, University of Southern California School of Dentistry. Requests for reprints should be directed to Dr. Goodman, 1800 N Highland Ave, Suite 305, Hollywood, Calif 90028. References 1. Henriksen, S.D. Studies in gramnegative anaerobes; gram-negative anaerobic rods with spreading colonies. Acta

Pathol Microbiol Scand 25:368, 1948. 2. Holm, P. Studies on the etiology of human actinomycosis; "Other microbes" of actinomycosis and their importance. Acta Pathol Microbiol Scand 27:736, 1950. 3. Eiken, M. Studies on an anaerobic, rod-shaped, gram-negative microorganism: Bacteroides corrodens, n. sp. Acta Pathol Microbiol Scand 43:404, 1958. 4. Henriksen, S.D. Corroding bacteria from the respiratory tract. Moroxella. Ringii. Acta Pathol Microbiol Scand 75: 85, 1969. 5. Henriksen, S.D. Corroding bacteria from the respiratory tract. Bacteroides corrodens. Acta Pathol Microbiol Scand 75:91, 1969. 6. Jackson, F.L.; Goodman, Y.E.; Bel, F.R.; and others. Taxonomic status of facultative and strictly anaerobic "corroding bacilli" that have been classified as Bacteroides corrodens. J Med Microbiol 4:171 May 1971. 7. Jackson, F.L., and Goodman, Y.E. Transfer of the facultatively anaerobic organism Bacteroides corrodens Eiken to a new genus Eikenella. lnt J System Bact 22:73 1972. 8. King, E.O. Round Table. Current trends in diagnostic microbiology. The identification of unusual pathogenic gram-negative bacteria. Department of Health, Education and Welfare, Public Health Service, Communicable Disease Center, Atlanta, Ga, 1964. 9. Riley, P.S.; Tatum, H.W.; and Weaver, R.E. Identity of HB-I of King and Eikenella corrodens (Eiken) Jackson and Goodman. lnt J System Bact 23:75 1973. 10. Editorial. HB-1 bacteria become Eikenella. Lancet 1:1227 June 2, 1973. 11. Khiarat, O. The non-aerobes of post-extraction bacteremia. J Dent Res 45:1191 July-Aug 1966. 12. Khiarat, O. Bacteroides corrodens isolated from bacteremias. J Pathol Bac: 94:29 July 1967. 13. Schilder, H. Cleaning and shaping the root canal. Dent Clin North Am 18:269 April 1974. 14. Schilder, H. Filling root canals in three dimensions. Dent Clin North Am 13:723 Nov 1967. 15. Zeldow, B.J. Microbiologic considerations in endodontics, in, Ingle, J.l. (ed) Endodontics. Philadelphia, Lea and Febiger, 1965, p 484. 16. Dorff, G.J.; Jackson, L.J.; and Rytel, M.W. Infections with Eikenella corrodens. Ann Intern Med 80:305 March 1974. 29

Eikenella corrodens found in root canal system of human tooth.

CASE REPORTS EIKENELLA CORRODENS FOUND IN ROOT CANAL SYSTEM OF HUMAN TOOTH A n t h o n y D. G o o d m a n , DDS, MSD, Los A n q e l e s E i k e n e...
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