756 Y Clin Pathol 1994;47:756-759 Evaluation of API Coryne system for identifying coryneform bacteria J Clin Pathol: first published as 10.1136/jcp.47.8.756 on 1 August 1994. Downloaded from A Soto, J Zapardiel, F Soriano Abstract that are aerobe or facultatively aerobe, non- Aim-To identify rapidly and accurately spore forming organisms of the following gen- coryneform bacteria, using a commercial era: Corynebacterium, Listeria, Actinomyces, strip system. Arcanobacterium, Erysipelothrix, Oerskovia, Methods-Ninety eight strains of Cory- Brevibacterium and Rhodococcus. It also per- nebacterium species and 62 additional mits the identification of Gardnerella vaginalis strains belonging to genera Erysipelorix, which often has a diphtheroid appearance and Oerskovia, Rhodococcus, Actinomyces, a variable Gram stain. Archanobacterium, Gardnerella and We studied 160 organisms in total from dif- Listeria were studied. Bacteria were ferent species of the Corynebacterium genus, as identified using conventional biochemi- well as from other morphological related gen- cal tests and a commercial system (API- era or groups, some of them not included in Coryne, BioMerieux, France). Fresh rab- the API Coryne database. bit serum was added to fermentation tubes for Gardnerella vaginalis isolates. Results-One hundred and five out ofthe Methods 160 (65.7%) organisms studied were cor- The study was carried out on Gram positive rectly and completely identified by the bacilli belonging to the genera Coryne- API Coryne system. Thirty five (21.8%) bacterium, Erysipelothrix, Oerskovia, Rhodococcus, more were correctly identified with addi- Actinomyces, Arcanobacterium, Gardnerella and tional tests. Seventeen (10-6%) organisms Listeria included in the API Coryne database were not identified by the system and (table 1). We also studied some organisms three (1.9%) were misidentified. belonging to genera that occasionally present Conclusions-The system was a good a diphtheroid appearance and are not alternative for identification of coryne- included in the system database (table 2). A form organisms. When occasionally per- total of 160 organisms were evaluated, includ- http://jcp.bmj.com/ formed with some additional tests, this ing 42 reference strains. Clinical isolates were method permits reliable and rapid identi- obtained from blood (seven isolates), skin (17 fication of coryneform organisms com- isolates), urine (13 isolates), calcule (one iso- pared with conventional methods. late), drainage (one isolate), exudate (one iso- late) and abscess (one isolate). The rest of the (7 Clin Pathol 1994;47:756-759) organisms came from stock collections. All the strains were kept at - 70°C before use and on September 27, 2021 by guest. Protected copyright. cultivated either aerobically or, if necessary, in Human infections by Coryneform sp are not a CO, atmosphere for 24 to 48 hours at 35°C only increasing but microbiologists are more on heart-infusion agar supplemented with 5% aware of their possible importance, mainly in sheep blood. high risk and immunosuppressed patients. The strains were identified using tech- Over the past two decades other Coryne- niques cited by Hollis and Weaver,"3 Bayston bacterium species, different from Coryne- and Higgins,'4 Coyle' and others.'5-'7 The fol- bacterium diphtheriae, have been found in lowing tests were used: Gram staining; colony severe infections in people.'-3 Bacteraemia, pigmentation; haemolysis; catalase produc- endocarditis, peritonitis, osteomyelitis and tion; urease utilisation, gelatin, hippurate and infection of the urinary and respiratory tracts aesculin hydrolysis; the Voges-Proskauer reac- are the most common infections associated tion; nitrate reduction; acid production from Department of with Corynebacterium sp.4 l glucose, maltose, mannitol, xylose, sucrose, Clinical Microbiology, These bacteria, which are common in clini- lactose and glycogen in fermentation broth, Fundacion Jimenez Diaz, Madrid, Spain cal samples, may be disregarded by microbiol- with the addition of 10% rabbit serum for A Soto ogists partly because they are considered Gardnerella vaginalis. Oxidation and fermenta- J Zapardiel non-pathogenic or "contaminant," but also tion tests were performed for C aquaticum F Soriano because there are no simple methods to iden- strains. Casein, xanthine, and tyrosine hydrol- Correspondence to: Dr A Soto, Department of tify them correctly in a routine laboratory.2 ysis were used to identify Nocardia spp. Most Infectious Diseases and Interest is increasing in the isolation and iden- of the strains were identified to species level Bacteriology, Royal Postgraduate Medical tification of these organisms, and this led us to using these tests but Oerskovia spp were only School, Hammersmith evaluate the API Coryne system by comparing identified to genus level. Hospital, Du Cane Road, London W12 ONN it with conventional identification methods. The API Coryne system consists of 20 Accepted for publication This system is a micromethod for the identifi- microtubes containing dehydrated substrates 9 February 1994 cation of Gram positive Coryneform organisms for the demonstration of 11 enzymatic Evaluation ofAPI Cotyne system 757 Table 1 Corynebacterium species and related genera studied included in the API Coryne The readings, except for the aesculin, ure- database ase, and gelatin tests, were done after adding Strains Total Clinical Stock Reference the appropriate reagents. The fermentation J Clin Pathol: first published as 10.1136/jcp.47.8.756 on 1 August 1994. Downloaded from Corynebacterium urealyticum 27 22 2 ATCC 43042, reactions were considered positive when they ATCC 43043, ATCC 43044 turned yellow. Identification was made using Corynebacteriumjeikeium 22 15 5 ATCC 43734, CCUG 24871 Corynebacterium striatum 5 4 ATCC 6940 the table provided by BioMerieux and, when Corynebacterium xerosis 5 4 ATCC 373 there were difficulties, by contacting the API Corynebacterium diphtheriae 2 2 Corynebacterium pseudotuberculosis 4 3 ATCC 19410 computer service. The interpretation was car- Corynebactenium bovis 2 ATCC 7715, CCUG 2705 ried out adding data on macroscopic and Corynebacterium pseudodiphtheriticum 5 4 ATCC 10700 Corynebacterum kutscheri 2 1 ATCC 15677 microscopic morphology, catalase, and Corynebacterium renale 2 1 ATCC 19412 haemolysis, as well as the numerical profile of Corynebacterium cystitidis 1 ATCC 29593 Corynebacterium pilosum 1 ATCC 29592 the API Coryne system. Corynebacterium minutissimum 2 ATCC 23348, CCUG 541 All the strains with a profile of "acceptable" Corynebacterium ulcerans 6 4 CCUG 16556, NCTC 7907 Corynebacterium aquaticum 3 2 ATCC 14665 identification or better were considered cor- Coryneform CDC group F, 3 1 2 rectly identified. Some additional tests were Coryneforn CDC group A4 2 2 Corynefonn CDC group G, 1 1 performed on those strains with a profile of Oerskovia sp 4 3 ATCC 25835 "good identification to genus" within the Erysipelothrix rhusiopathiae 4 4 Rhodococcus equi 8 1 7 group C renaleiC cystitidis and C aquaticuml Listeria monocytogenes 11 9 ATCC 19111,NCTC 11994 Coryneform CDC group A, according to the Listeria innocua 2 2 Listeria murrayi 1 ATCC 25401 manufacturer's protocol. These tests included Listeria grayi 1 ATCC 25400 growth in 6% sodium chloride, production of Listeria ivannovii 1 1 Listeria seeligeri 2 2 acid from trehalose or fructose, the Voges- Arcanobacterium haemolyticum 5 4 ATCC 9345 Proskauer reaction, the CAMP test, growth at Actinomyces pyogenes 4 3 ATCC 19411 GardnereUla vaginalis 4 1 2 ATCC 14018 a pH of 5-4 and Tween-80 hydrolysis. The strains with a profile of "low", "doubtful" or "insufficient discrimination" were considered unidentified. When the profile was good at Table 2 Other species studied not included in the API Coryne database species level but did not match the conven- Strains Total Clinical Stock Reference tional identification, it was considered incor- rectly identified. Corynebacterium ammoniogenes 1 ATCC 6871 Corynebacterium callunae 1 ATCC 15991 Corynebacteriumflavescens 1 ATCC 10340 Corynebacterium vitarumen 1 ATCC 10234 Clavibacter michiganense 1 CCUG 580 Results Curtobacteriumflaccumfaciens 1 CCUG 23824 Of the 160 organisms studied using the API Rhodococcus rhodochrous 1 ATCC 11048 Propionibacterium avidum 2 1 ATCC 25577 system, 105 (65-7%) of them were correctly Propionibacterium granulosum 1 ATCC 25564 and completely identified in 24 hours to Rothia dentocariosa 2 1 ATCC 17931 Nocardia asteroides 2 species level, 35 more (21-8%) were incom- 1 ATCC 19247 http://jcp.bmj.com/ Nocardia brasiliensis 1 ATCC 19296 pletely identified but finally correctly identi- Nocardiafarcinica 1 ATCC 3318 Lactobacillus acidophilus 2 1 ATCC 832 fied with additional tests, 17 (10.6%) were not identified as the profile number did not correspond to any organism, and in three (1 9%) cases the strains were misidentified. activities (nitrate reduction, pyrazinamidase, Most strains (87 5%) were correctly identified alkaline in 24 hours or after additional pyrrolidonyl arylamidase, phos- tests (table 3). on September 27, 2021 by guest. Protected copyright. phatase, glucuronidase, ,B galactosidase, Six strains of Cjeikeium had a good profile at a glucosidase, N-Acetyl-f,glucosaminidase, genus level (profile number 2100324) and aesculin, urease and hydrolysis of gelatin) or may represent a less common biotype. the fermentation of eight sugars (glucose, Additional tests were required for correct ribose, xylose, mannitol, maltose, lactose, identification (growth in 6%