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Int. J. Med. Microbiol. 290, 285-287 (2000) © Urban & Fischer Verlag http://www.urbanfischer.de/journals/ijmm
Catalase-negative Actinomyces neuii subsp. neuii isolated from an infected mammary prosthesis Simone Brunner1, Susanne Graf2, Philippe Riegel 3, Martin Altwegg 1 1 2
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Department of Medical Microbiology, University of Zurich, CH-8028 Zurich, Switzerland Department of Gynecology, Kantonsspital Winterthur, CH-8401 Winterthur, Switzerland Institut de Bacteriologie de la Faculte de Medecine, F-67000 Strasbourg, France
Received December 28, 1999 . Revision received February 23, 2000 . Accepted February 28, 2000
Abstract In this case report a catalase-negative strain of Actinomyces neuii subsp. neuii is described as the possible causative agent of an infected mammary prosthesis. DNA hybridization studies and 16S rRNA analysis confirmed that the strain belongs to the species Actinomyces neuii subsp. neuii. Since this str;;n is the first A. neuii subsp. neuii strain reported to be catalase negative, the catalase reaction should no longer be considered a key reaction for the diagnosis of this species but must be interpreted in conjunction with other characteristics. Key words: Actinomyces neuii - catalase reaction - mammary prosthesis inflammation
Introduction Actinomyces neuii subsp. neuii belongs to the coryneform bacteria. In 1987, Na'was et al. described this aerobically growing catalase-positive coryneform bacterium which was designated CDC fermentative coryneform group 1 (Na'was et al., 1987). Studies of the metabolic and cellular fatty acid patterns as well as composition of cell wall (Funke et al., 1993) led to the suggestion that this group belongs to the genus Actinomyces. 165 rRNA sequencing confirmed this suggestion (Funke et al., 1994). The name Actinomyces neuii subsp. neuii was proposed for CDC group 1 and Actinomyces neuii subsp. anitratus for CDC group 1-like (nitrate-negative) strains (Funke et al., 1994). Actinomyces neuii subsp. neuii strains have been isolated mainly from abscesses in association with mixed
anaerobic flora and from human blood cultures (Funke and von Graevenitz, 1995; Funke et al., 1993). We describe the first catalase-negative strain of Actinomyces neuii subsp. neuii presumed to be the possible causative agent of an infected mammary prosthesis.
Case report A 64-year-old woman was admitted to the hospital because of an exulcerating skin lesion in the lower exterior quadrant with herniation of a right-side mammary prosthesis. No signs of systemic infection were seen. In 1972, bilateral mastectomy because of cystic mastopathy and 'carcinophobia' had been performed with implantation of silicon prostheses. The patient had been asymptomatic since this time. Surgery was performed for revision of the right infected prosthesis.
Corresponding author: S. Brunner, Institut fur Medizinische Mikrobiologie, GloriastraRe 32, CH-8028 Zurich, Phone: +4116342752, Fax: +4116344906, E-mail:
[email protected] 1438-4639/00/203/3-285 $ 12.00/0
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Preoperatively, amoxicillinlclavulanate 2 X 2.2 g q. d. was given. At surgery, the right prosthesis was removed, and a swab was taken from the prosthesis and sent to the Department of Medical Microbiology. The fibrotic capsule was excised. Histologic examination of the rem~ved parts showed inflamed tissue with granulocytes but no signs of malignancy. Postoperatively, 1.2 g amoxicillinlclavulanate was given after 8 and 16 hours. The wound healed without complications, and the patient was discharged after one week. A Gram stain of the lesion showed numbers of granulocytes and a few Gram-positive cocci. The tissue was treated as described earlier (Funke et al., 1993). Beside some colonies of coagulase-negative staphylococci and a mixed anaerobic flora, whitish ahemolytic colonies were recovered from sheep blood agar after 24 hours. However, Actinomyces species might have grown on many other common bacteriological media (Rodloff et al., 1999). Growth was equally well under aerobic and anaerobic conditions. A Gram stain of these colonies showed Gram-positive rods. No branching filaments which are typical for many other Actinomyces species were observed (Funke and von Graevenitz, 1995). Traditional media were used for biochemical characterization (Funke et al., 1993). The rods were fermentative, nonmotile and non-spore forming. The catalase reaction (Lauderdale et al., 1999), esculin and urea hydrolysis were negative. Nitrate was reduced; glucose, maltose, lactose, mannitol, and xylose were fermented. The CAMP test was positive. There was no better growth on blood agar with Tween 80 than without Tween. ONPG and a-glucosidase tests were positive. Metabolic fatty acids produced from glucose were acetate and succinate. This pattern was entirely in line with Actinomyces neuii subsp. neuii except for the catalase reaction (Funke et al., 1993, 1994; von Graevenitz and Funke, 1996). The data base of the API Coryne system (Version 2.0) identified the agent as Actinomyces neuii subsp. neuii (API code 3410771) with a T value of 0.26. Contradictory reactions were the lack of catalase activity, and the ability to ferment xylose and lactose. The strain was susceptible to erythromycin, penicillin, tetracycline and vancomycin by the NCCLS technique. The major cellular fatty acids were: C14: 0 (8.2%), C16:1 w9c (8.4%), C16:0 (63.2%), and C18:1 w9c (11.4%). Partial sequencing of the 16S rRNA gene showed a sequence similarity of 99.2 % (352/355 nucleotides) between the sequence of this strain as compared to the A. neuii reference sequence (accession number Z 33613 in GenbankiEMBL). The results of DNA hybridization experiments (Grimont, 1999) indicated a DNA relatedness between the type strain of A. neuii subsp."" neuii and our strain of more than 95 %.
Discussion Because of morphological and chemotaxonomic characteristics and the production of the metabolic fatty acids the diagnosis of Actinomyces sp. seemed probable. Analysis of the cellular fatty acids revealed that the strain could be assigned to the genus Actinomyces but its profile is not distinct enough from other Actinomyces spp. (Na'was et al., 1987). The positive CAMP, ONPG and a-glucosidase tests strongly supported our diagnosis of an Actinomyces neuii subsp. neuii in spite of the repeatedly negative catalase reaction. In contrast to other biochemical tests, the catalase reaction generally does not much vary within one species (Kasten et al., 1998). Generally, Actinomyces species are catalase-negative except for Actinomyces viscosus and A. neuii (Rodloff et al., 1999) which are catalase-positive, with the exception of the strain of A. neuii subsp. neuii described here. A new species was ruled out by molecular methods, i. e., 16S rRNA analysis and DNA hybridization. For Staphylococcus aureus, repeatedly catalase-negative strains have been described (Carlson and Gorin, 1981). A majority of the strains of A. neuii subsp. neuii was isolated in this institution from abscesses in association with mixed anaerobic flora (Funke and von Graevenitz, 1995). This fact fits to our findings. We conclude that the catalase reaction should no longer be considered a key reaction for the diagnosis of Actinomyces neuii subsp. neuii but interpreted in conjunction with the other characteristics. Acknowledgement. We thank A. von Graevenitz for carefully reading the manuscript.
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