Comparison of biochemical, morphologic, and chemical characteristics of Centers for Disease Control fermentative coryneform groups 1, 2, and A-4.

A total of 24 strains of fermentative coryneform like bacteria isolated from clinical specimens form two distinct groups which have been designated Centers for Disease Control (CDC) fermentative coryneform groups 1 (13 strains) and 2 (11 strains). The phenotypic characteristics of group 1 were similar to those of a previously described CDC group designated A-4, with the major differentiating characteristic being the inability to hydrolyze esculin. Major differences in cellular fatty acid composition between CDC groups 1 and A-4 were also observed. The branched-chain fatty acids 14-methylhexadecanoate and 12-methyltetradecanoate, which account for more than 80% of the total acids of group A-4, were not detected in cells of group 1 strains. Groups 1 and 2, which have similar cellular fatty acid compositions, can be differentiated on the basis of fermentation of xylose, mannitol, lactose, sucrose, and melibiose by group 1 but not by group 2. The sources of isolation of the strains of both groups varied. Only group 1 strains were associated with eye infections.     

Phenotypic and genetic characterization of clinical isolates of CDC coryneform group A-3: proposal of a new species of Cellulomonas, Cellulomonas denverensis sp. nov

CDC coryneform group A-3 bacteria are rare human pathogens. In this study, six group A-3 isolates (two from blood, one from cerebrospinal fluid, and one each from homograft valve, lip wound, and pilonidal cyst) were compared to the type strains of phenotypically related organisms, Cellulomonas fimi, Cellulomonas hominis, Oerskovia turbata, and Sanguibacter suarezii, and characterized by phenotypic, chemotaxonomic, and genotypic studies. DNA-DNA reassociation analysis identified two genomic groups, and phylogenetic analysis of the 16S rRNA gene sequence identified the taxonomic positions of these groups to genus level. Two groups were defined, and both were more closely related to Cellulomonas species: one group of three strains, for which we propose the new species Cellulomonas denverensis sp. nov., with the type strain W6929 (ATCC BAA-788(T) or DSM 15764(T)), was related to C. hominis ATCC 51964(T) (98.5% 16S rRNA gene sequence similarity), and the second group of three strains was related to C. hominis ATCC 51964(T) (99.8 to 99.9% 16S rRNA gene sequence similarity). The definition of this new Cellulomonas species and the confirmation of three strains as C. hominis serve to further clarify the complex taxonomy of CDC coryneform group A-3 bacteria and will assist in our understanding of the epidemiology and clinical significance of these microorganisms.     

Primary identification of Microbacterium spp. encountered in clinical specimens as CDC coryneform group A-4 and A-5 bacteria.

Over nearly two decades, 13 yellow- or orange-pigmented, fermentative gram-positive rods belonging to the genus Microbacterium were encountered in clinical specimens. All 13 strains, 10 of which came from blood cultures, were initially identified as CDC coryneform group A-4 and A-5 bacteria according to the scheme of Hollis and Weaver for the identification of gram-positive rods. The clinical isolates were compared with the type strains of the six species constituting the genus Microbacterium as well as with three Microbacterium strains isolated from hospital environments. By biochemical methods only 5 of 13 clinical isolates could be identified to species level. Peptidoglycan analysis proved to be a valuable tool for differentiation between Microbacterium spp. and related genera, whereas cellular fatty acid analysis did not allow species identification within the genus Microbacterium. The 22 Microbacterium strains studied were, in general, susceptible to antimicrobial agents used in the treatment of infections caused by gram-positive rods. This report is the first one concerning the isolation of Microbacterium strains from clinical specimens. The sources as well as the mode of transmission remain to be established.     

Cellular fatty acid composition and phenotypic and cultural characterization of CDC fermentative coryneform groups 3 and 5.

Seventy strains of fermentative, asporogenous, gram-positive coccobacilli or short rods form two closely related groups which have been designated CDC fermentative coryneform groups 3 (32 strains, xylose fermenters) and 5 (38 strains, xylose nonfermenters). The two taxa are otherwise similar to each other phenotypically and culturally and by a distinctive Staphylococcus-like odor and by cellular fatty acid (CFA) composition. CDC group 3 and CDC group 5 strains have been isolated from clinical sources (blood, abscesses, and wounds but not urine or respiratory specimens) in Canada and the United States and among referrals from Belgium, Sweden, and Spain. Coryneform CDC group 3 strains were phenotypically similar to CDC coryneform group A-3 but were distinguishable by their inability to reduce nitrate and by their lack of motility. Coryneform CDC group 5 isolates were phenotypically somewhat similar to Actinomyces viscosus and Rothia dentocariosa, except that none of this group reduced nitrate. Both CDC groups could be differentiated from these similar bacteria by the ability to decarboxylate lysine and ornithine. The CFA compositions of CDC group 3 and 5 strains were similar to each other, were distinctive from those of other coryneforms, and were of the branched-chain type. API CORYNE codes were consistent for both CDC group 3 and CDC group 5 bacteria, suggesting that this method could be useful as an identification method.     

Characteristics of CDC group 3 and group 5 coryneform bacteria isolated from clinical specimens and assignment to the genus Dermabacter.

Over a 1-year period, 11 isolates (including 5 from blood cultures) of the recently described CDC group 3 and group 5 coryneform bacteria were derived from clinical specimens and compared with reference strains. Biochemical characteristics indicated a very close relationship between CDC group 3 and group 5 coryneform bacteria. The ability of CDC group 3 and the inability of CDC group 5 coryneform bacteria to ferment xylose were the only reactions that were different for the two taxa. Chemotaxonomic features of the two groups included the presence of meso-diaminopimelic acid, a lack of mycolic acids, and the presence of predominantly branched cellular fatty acids, a combination found among gram-positive rods only in Brevibacterium spp., Brachybacterium faecium, and Dermabacter hominis. 16S rRNA gene sequence analysis revealed that CDC group 3 and group 5 coryneform bacteria are members of the genus Dermabacter, which to date has been isolated exclusively from human skin.     

Recognition of Dermabacter hominis, formerly CDC fermentative coryneform group 3 and group 5, as a potential human pathogen.

Thirty strains of fermentative coryneform-like bacteria designated CDC fermentative coryneform group 3 and coryneform group 5 were compared biochemically by cellular fatty acid analysis and by DNA relatedness with the type strain of Dermabacter hominis, ATCC 49369. DNA from 22 strains of both CDC groups showed 69 to 96% relatedness (hydroxyapatite method) to labeled DNA from ATCC 49369 and to DNA from CDC group 3 strain G4964, and the strains are considered to belong to D. hominis. The remaining eight strains were genetically but not phenotypically differentiable from D. hominis. They were genetically heterogeneous, but hybridization results indicated that they probably belong to the genus Dermabacter. Thirteen of the 22 D. hominis strains and all 8 of the other Dermabacter strains had been isolated from blood, which indicates the pathogenic potential of this species and genus.     

High-performance liquid chromatography of corynomycolic acids as a tool in identification of Corynebacterium species and related organisms.

A high-performance liquid chromatography (HPLC) study of 307 strains of Corynebacterium species and related taxa revealed that strains classified as "Corynebacterium aquaticum"; "Corynebacterium asperum"; and Centers for Disease Control (CDC) groups 1, 2, A-3, A-4, A-5, B-1, B-3, E, F-2, and I-2 as well as some unidentified coryneforms do not contain any corynomycolic acids; therefore, they should not be included in the genus Corynebacterium. Such an HPLC method of identification permitted the correct assignment to the genus Rhodococcus of two unpigmented strains of coryneform bacteria whose mycolic acid profiles were comparable to those of Rhodococcus equi. Bacteria belonging to CDC groups ANF-1, ANF-3, F-1, G-1, G-2, and I-1, as well as some other Corynebacterium sp. strains, yielded corynomycolic acid HPLC patterns related to those of Corynebacterium species. Either similarities or differences were observed in the corynomycolic acid profiles of Corynebacterium species tested after culture on sheep blood agar and/or sheep blood agar supplemented with Tween 80, which demonstrated that identification at the species or group level is possible. However, Corynebacterium striatum and CDC group I-1 bacteria as well as CDC group G-1 and group G-2 bacteria had indistinguishable HPLC patterns. Conversely, some variations were observed within some species as Corynebacterium xerosis, C. striatum, and Corynebacterium minutissimum. The evaluation procedure of this HPLC method by mass spectrometry analysis of isolated eluted peaks revealed that analytical reverse-phase HPLC alone does not provide any structural information, since isomers with identical polarities coeluted as a single peak. Nevertheless, HPLC is a rapid and reliable method for identification of corynomycolic acid-containing bacteria in the clinical microbiological laboratory.     

Characterization of Brevibacterium spp. from clinical specimens.

Nonfermenting coryneform bacteria identified as Brevibacterium spp. were isolated from routine clinical specimens. Four strains were derived from peritoneal fluid and has presumably been involved in the pathogenesis of continuous ambulatory peritoneal dialysis peritonitis. Another five isolates most probably represented skin contaminants. Cell wall and lipid analyses confirmed the genus identification. Strains in this taxon are difficult to distinguish from other biochemically inactive and nonmotile coryneform species but show characteristics cellular fatty acid profiles. In vitro susceptibilities to commonly used antibiotics were determined.     

Isolation and characterisation of toxin A-negative, toxin B-positive Clostridium difficile in Dublin, Ireland

Clostridium difficile is a major cause of infectious diarrhoea in hospitalised patients. Most pathogenic C. difficile strains produce two toxins, A and B; however, clinically relevant toxin A-negative, toxin B-positive (A- B+) strains of C. difficile that cause diarrhoea and colitis in humans have been isolated worldwide. The aims of this study were to isolate and characterise A- B+ strains from two university hospitals in Dublin, Ireland. Samples positive for C. difficile were identified daily by review of ELISA results and were cultured on selective media. Following culture, toxin-specific immunoassays, IMR-90 cytotoxicity assays and PCR were used to analyse consecutive C. difficile isolates from 93 patients. Using a toxin A-specific ELISA, 52 samples produced detectable toxin. All isolates were positive using a toxin A/B ELISA. Similarly, all isolates were positive with the cytoxicity assay, although variant cytopathic effects were observed in 41 cases. PCR amplification of the toxin A and toxin B genes revealed that 41 of the previous A- B+ strains had a c. 1.7-kb deletion in the 3'-end of the tcdA gene. Restriction enzyme analysis of these amplicons revealed the loss of polymorphic restriction sites. These 41 A- B+ isolates were designated toxinotype VIII by comparison with C. difficile strain 1470. PCR ribotyping revealed that all A- B+ isolates belonged to PCR-ribotype 017. A- B+ C. difficile isolates accounted for 44% of the isolates examined in this study, and appeared to be isolated more frequently in Dublin, Ireland, than reported rates for other countries.     

Evaluation of API Coryne system for identifying coryneform bacteria.

AIM--To identify rapidly and accurately coryneform bacteria, using a commercial strip system. METHODS--Ninety eight strains of Corynebacterium species and 62 additional strains belonging to genera Erysipelothrix, Oerskovia, Rhodococcus, Actinomyces, Archanobacterium, Gardnerella and Listeria were studied. Bacteria were identified using conventional biochemical tests and a commercial system (API-Coryne, BioMèrieux, France). Fresh rabbit serum was added to fermentation tubes for Gardnerella vaginalis isolates. RESULTS--One hundred and five out of the 160 (65.7%) organisms studied were correctly and completely identified by the API Coryne system. Thirty five (21.8%) more were correctly identified with additional tests. Seventeen (10.6%) organisms were not identified by the system and three (1.9%) were misidentified. CONCLUSIONS--The system was a good alternative for identification of coryneform organisms. When occasionally performed with some additional tests, this method permits reliable and rapid identification of coryneform organisms compared with conventional methods.     

Corynebacterium resistens sp. nov., a new multidrug-resistant coryneform bacterium isolated from human infections

Five strains of an unknown, multidrug-resistant coryneform, gram-positive rod were isolated from blood, bronchial aspirate, and abscess specimens. Four of the five strains isolated were highly resistant to antimicrobial agents, including beta-lactams, aminoglycosides, macrolides, quinolones, and tetracyclines, except for glycopeptides. In immunocompromised patients, bacteremia associated with this organism was rapidly fatal. This coryneform bacterium was nonmotile, lipophilic, and nonsaccharolytic. Lack of pyrazinamidase activity differentiated this organism from other lipophilic corynebacteria. Chemotaxonomic studies indicated that this multidrug-resistant coryneform bacterium belongs to the genus Corynebacterium. Comparative 16S rRNA gene sequencing and DNA-DNA hybridization analyses revealed that the five isolates were genetically identical and that they represent a new subline within the genus Corynebacterium, for which we propose the designation Corynebacterium resistens sp. nov. The type strain of Corynebacterium resistens is GTC 2026T (SICGH 158T, JCM 12819T, CCUG 50093T).     

The microbiology of endophthalmitis: global trends and a local perspective

Endophthalmitis is a rare but frequently devastating infection, caused by diverse organisms, including bacteria, viruses, fungi, and parasites. The causative agents of endophthalmitis vary according to the mechanism. The involvement of intraocular structures can result from exogenous spread from ocular trauma, infection of adjacent structures, or as a complication of intraocular surgery. Of the causes of exogenous endophthalmitis, post-operative endophthalmitis is the most frequently encountered; specifically, cataract surgery is the most frequent eye surgery and, thus, leads the list of surgery-associated endophthalmitis. Exogenous source is far more common than endogenous endophthalmitis, a disease that is caused by the hematogenous spread of organisms from a remote infectious site to the eye, leading to severe visual loss. Several large series estimate that endogenous endophthalmitis accounts for 2–15?% of all cases of endophthalmitis. Progressive vitritis is a hallmark for all forms of endophthalmitis, accompanied by intraocular inflammation, loss of vision, pain, and hypopyon. The common presentation consists of reduced vision, conjunctival injection, pain, and eyelid swelling. We reviewed the microbiology of endophthalmitis during a 9-year period in Winnipeg, Canada. Gram-positive bacteria with coagulase-negative staphylococci are the most common causative organisms, reflecting the association with surgical procedures.     

Human infections caused by Brevibacterium casei, formerly CDC groups B-1 and B-3.

Forty-one clinical strains of CDC coryneform groups B-1 and B-3 were compared biochemically, by analysis of cell wall sugars, amino acids, and cellular fatty acids, and by DNA relatedness to the type strains of Brevibacterium casei, Brevibacterium epidermidis, and Brevibacterium linens. Twenty-two strains were shown to be B. casei, while five other strains formed a phenotypically inseparable genomospecies in the same genus. The remaining isolates were genetically heterogeneous, and most are probably members of the genus Brevibacterium. They were not further identified, but they were biochemically distinguishable from B. casei. Eleven of the clinical strains of B. casei were isolated from blood, and two each were isolated from cerebrospinal fluid and from pleural fluid. At least five isolates were from multiple blood or cerebrospinal fluid cultures. To our knowledge, these strains are the first described clinical isolates identified as B. casei, which was previously considered to be a nonpathogenic species.     

Differentiation of Corynebacterium spp., Listeria spp., and related organisms by using fluorogenic substrates.

A total of 228 strains of Arcanobacterium haemolyticum, Corynebacterium spp., Erysipelothix rhusiopathiae, and Listeria spp. were investigated for their abilities to hydrolyze 60 different fluorogenic 4-methylumbelliferyl-linked and beta-naphthylamide-linked substrates within 6 and 24 h of incubation. The hydrolysis of a group of 16 fluorogenic substrates, and in particular, the glycosidase tests, in most cases showed high separation values at the genus level. When used in combination with other biochemical tests, these tests improved the differentiation of coryneform bacteria and phenotypically similar organisms.     

Bacteremia caused by Brevibacterium species in a patient with chronic lymphocytic leukemia

We report a case of bacteremia caused by Brevibacterium species which is one of the coryneform bacteria, in a patient with chronic lymphocytic leukemia. We conclude that, if a coryneform bacteria is isolated from sterile body sites, it must be carefully evaluated, and especially in immunocompromised patients, Brevibacterium species should be considered as potential pathogens.     

Enterobacter cloacae Endophthalmitis: Report of Four Cases

Members of the genus Enterobacter are commensal organisms of the gastrointestinal tract and are considered pathogenic only for patients with lowered resistance to infection (e.g., chronic infection, cancer, or diabetes mellitus) or those with impaired immunity (congenital, acquired, or impaired immunity secondary to therapy). We report on four cases of endophthalmitis caused by Enterobacter cloacae: two in patients with acute postoperative endophthalmitis, one in a patient with delayed bleb-related endophthalmitis, and one in a patient presenting with presumed posttraumatic endophthalmitis. Each patient presented with severe disease many days after the onset of ocular symptoms, and two patients had systemic risk factors accounting for a reduced resistance to infection. Endophthalmitis caused by gram-negative bacilli is characterized by acute onset, rapid progression, and poor final visual outcome. Each of these patients was treated by a standard protocol with intravitreal, systemic, and topical antibiotics and systemic steroids. Despite treatment, the final visual outcomes for three of these patients was no perception of light, and that for one patient remained perception of hand movements only. In common with endophthalmitis caused by other gram-negative organisms, intraocular infection secondary to Enterobacter cloacae infection is a devastating disease which, despite treatment, results in extensive ocular damage and severe visual loss. Since 1966, only four cases of endophthalmitis secondary to infection with members of this genus have been reported. This report presents four cases which occurred over a period of 14 months and, to the best of our knowledge, the first case of bleb-related endophthalmitis secondary to E. cloacae infection.     

Septic arthritis due to Arcanobacterium haemolyticum

Diphtheroids or "coryneform" bacilli are usually considered to be nonpathogenic "normal flora" of human skin and mucous membranes. Because bacterial cultures are frequently contaminated with these organisms the correct diagnosis and treatment may be delayed by the failure to recognize serious infections caused by them. Few confirmed cases of orthopaedic infections due to Arcanobacterium haemolyticum infection have been reported, partly because of inadequate identification of this bacterium. We report a case of septic arthritis due to A. haemolyticum.     

Recent Clinical Manifestation and Prognosis of Fungal Endophthalmitis: A 7-Year Experience at a Tertiary Referral Center in Korea

This study analyzed the recent causes, prognosis, and treatment strategies for fungal endophthalmitis. A retrospective review of patients who were diagnosed with fungal endophthalmitis at our center was conducted. The fungal organisms isolated from each patient and the visual prognosis according to the route of infection and treatment method were analyzed. A total of 40 eyes from 30 patients with fungal endophthalmitis were included in this study. Candida species were the most common causative organisms in 35 of 40 eyes. Endogenous and exogenous endophthalmitis were observed in 33 and 7 eyes, respectively. Pre- and post-treatment best-corrected visual acuity (BCVA) was not significantly different between endogenous endophthalmitis and exogenous endophthalmitis. The 40 eyes were treated using the following modalities: intravitreal antifungal agent injection with intravenous antifungal agent (16 eyes), vitrectomy with intravenous antifungal agent (14 eyes), intravenous antifungal agent alone (9 eyes), and evisceration (1 eye). Post-treatment BCVA only significantly improved after treatment in the vitrectomy group. Candida species were the most common cause of fungal endophthalmitis, irrespective of the route of infection. The visual prognosis of fungal endophthalmitis was generally poor. In conclusion, if the general condition of the patient tolerates a surgical procedure, prompt vitrectomy and intravitreal injection of antifungal agents can improve visual acuity.

Graphical Abstract

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Cellular fatty acid composition as an adjunct to the identification of asporogenous, aerobic gram-positive rods

Cellular fatty acid (CFA) compositions of 561 asporogenous, aerobic gram-positive rods were analyzed by gas-liquid chromatography as an adjunct to their identification when grown on blood agar at 35 degrees C. The organisms could be divided into two groups. In the first group (branched-chain type), which included coryneform CDC groups A-3, A-4, and A-5; some strains of B-1 and B-3; "Corynebacterium aquaticum"; Brevibacterium liquefaciens; Rothia dentocariosa; and Listeria spp., the rods had sizable quantities of antiesopentadecanoic (Ca15:0) and anteisoheptadecanoic (Ca17:0) acids. Other species with these types of CFA included B. acetylicum, which contained large amounts of isotridecanoic (Ci13:0) and anteisotridecanoic (Ca13:0) acids. CFAs useful for distinguishing among Jonesia denitrificans, Oerskovia spp., some strains of CDC groups B-1 and B-3, Kurthia spp., and Propionibacterium avidum were hexadecanoic (C 16:0) acid, isopentadecanoic (Ci15:0) acid, and Ca15:0). The second group (straight-chained type), which included Actinomyces pyogenes; Arcanobacterium haemolyticum; C. bovis; C. cystitidis; C. diphtheriae; C. flavescens, "C. gentalium"; C. jeikeium; C. kutscheri; C. matruchotii; C .minutissimum; C. mycetoides; C. pilosum; C. pseudodiphtheriticum; "C. pseudogenitalium"; C. pseudotuberculosis; C. renale; CDC groups 1, 2, ANF-1, D-2, E, F-1, F-2, G-1, G-2, and I-2; C. striatum; "C. tuberculostearicum"; C. ulcerans; C. vitarumen; C. xerosis; and Erysipelothrix rhusiopathiae, was typified by significant quantities of hexadecanoic (C16:0) and oleic acids (C18:cis9), with differences in the amounts of linoleic acid (C18:2), stearic acid (C18:0), an unnamed peak (equivalent chain length, 14.966), and small quantities of other known saturated and unsaturated fatty acids. CFA composition of these organisms was sufficiently discriminatory to assist in classification but could not be used as the sole means of identification.     

Taxonomy of some recently described avian Pasteurella/Actinobacillus-like organisms as indicated by deoxyribonucleic acid relatedness

Members of the family Pasteurellaceae Pohl 1981 are frequently encountered in birds as parasites or pathogens, e.g. the well-known species Pasteurella multocida, Pasteurella gallinarum, Haemophilus paragallinarum, and three species containing strains that had been previously classified as "Haemophilus avium"(Pasteurella avium, Pasteurella volantium, and an unnamed Pasteurella species defined by Mutters et al., 1985). A variety of additional taxa which had been tentatively assigned to the family do not belong to recognised species and could not even be classified to the genus level. In the present investigation selected Pasteurella/Actinobacillus-like isolates from fowl and zoo birds were examined for their genetic relationships with established species of Pasteurellaceae, using the renaturation method of deoxyribonucleic acid (DNA):DNA hybridisation. Guanine plus cytosine contents and genome masses were also considered. On the basis of DNA relatedness (1) the genus Pasteurella sensu stricto was extended to include Bisgaard's taxa 1 and 4 as two new Pasteurella species. (2) Bisgaard's taxa 2 and 3 and some phenotypically similar organisms isolated from zoo birds were shown to form a large distinct group which seems to represent a new genus with several species within the family Pasteurellaceae. (3) Another large heterogeneous, genus-like group consisted of strains labelled "Actinobacillus salpingitidis" and the phenotypically similar "Avian Pasteurella haemolytica-like" organisms; this group was placed in the close vicinity of the genus Actinobacillus. (4) Finally, a group of isolates labelled "Avian haemolytic Actinobacillus-like" organisms appeared to be heterogeneous on the species level but could be included in the genus Actinobacillus on the basis of DNA binding data. By co-evaluation of genetic relatedness and phenotypic features of avian Pasteurella/Actinobacillus-like isolates some diagnostically useful criteria have been detected.