Coryneform bacteria in infectious diseases: clinical and laboratory aspects

Three cases of opportunistic infection caused by propionic acid producing Corynebacterium minutissimum

Propionic acid producing strains of Corynebacterium minutissimum were isolated from three patients with opportunistic infections. One neutropenic patient was undergoing chemotherapy for prolymphocytic leukemia; the other two patients were undergoing hemodialysis and peritoneal dialysis respectively. An unusual feature of these three strains was their resistance to several antibiotics, which is seldom seen in diphtheroids other than Corynebacterium jeikeium and CDC group D2.

Gardnerella vaginalis: characteristics, clinical considerations, and controversies

The clinical significance, Gram stain reaction, and genus affiliation of Gardnerella vaginalis have been controversial since Gardner and Dukes described the organism as the cause of "nonspecific vaginitis," a common disease of women which is now called bacterial vaginosis. The organism was named G. vaginalis when taxonomic studies showed that it was unrelated to bacteria in various genera including Haemophilus and Corynebacterium. Electron microscopy and chemical analyses have elucidated the organism's gram-variable reaction. Controversy over the etiology of bacterial vaginosis was largely resolved by (i) studies using improved media and methods for the isolation and identification of bacteria in vaginal fluids and (ii) standardization of criteria for clinical and laboratory diagnosis. Besides G. vaginalis, Mobiluncus spp., Mycoplasma hominis, and certain obligate anaerobes are now acknowledged as participants in bacterial vaginosis. The finding that G. vaginalis, Mobiluncus spp., and M. hominis inhabit the rectum indicates a potential source of autoinfection in addition to sexual transmission. Extravaginal infections with G. vaginalis are increasingly recognized, especially when the toxic anticoagulant polyanetholesulfonate is omitted from blood cultures and when urine cultures are incubated anaerobically for 48 h. The finding that mares harbor G. vaginalis suggests that an equine model can be developed for studies of Gardnerella pathogenesis.

Evaluation of the rapid CORYNE identification system for Corynebacterium species and other coryneforms

The Rapid CORYNE system for identification of aerobic, nonsporeforming, gram-positive rods was evaluated according to the manufacturer's instructions with 177 organisms. After inoculation with a heavy suspension of growth, strips containing 20 cupules were incubated for 24 h, reagents were added, and the results of 21 biochemical reactions were recorded as numerical profiles. The strains consisted of pathogenic species of the genus Corynebacterium, primarily C. diphtheriae (n = 29), opportunistic species of Corynebacterium including C. jeikeium (n = 75), recognized species of non-corynebacteria such as Gardnerella and Arcanobacterium (n = 51), and Centers for Disease Control (CDC) coryneform groups (n = 22). Results from single tests read after 24 h yielded correct identifications to species level with no additional tests for 26 (89.7%) of the pathogenic species; 64 (85.3%) of the opportunistic organisms; 51 (100%) of the non-corynebacteria, and 8 (36.4%) of the CDC coryneform groups. Supplemental tests produced the correct identification for three additional pathogenic isolates (100% total) and four additional isolates from the opportunistic species (90.6% total). Twelve of the 15 isolates not identified by the system were in the CDC coryneform groups. Four of the six misidentified and one of the unidentified isolates were C. matruchotii, which was not included in the data base. The system is an excellent rapid alternative to conventional biochemical tests.

A case of urinary tract infection caused by Corynebacterium urealyticum and coryneform group F1

A case of urinary tract infection (UTI) caused by a fastidious, urea-splitting, antibiotic-sensitive coryneform, identified as CDC group F1, is described. The patient suffered from encrusted cystitis and had had previous and persistent UTIs caused by Corynebacterium urealyticum (formerly CDC group D2). Bacteriological cure was achieved after one month of treatment with amoxicillin plus acetohydroxamic acid.

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.

Human infections with Actinomyces pyogenes (Corynebacterium pyogenes)

Actinomyces pyogenes (Corynebacterium pyogenes), a well-known pathogen in many animals, was isolated from 11 Danish patients since 1968. Bacteriologic characteristics and clinical pictures of the patients are described. Ability to hydrolyze gelatine, to produce beta-glucuronidase, to reach with antisera against group-G streptococci, and to produce acid from xylose differentiates A. pyogenes from Arcanobacterium haemolyticum, with which it has at times been confused. Actinomyces pyogenes is an established, but often misrecognized, human pathogen that should be better known to clinical microbiologists.

Isolation of Corynebacterium group D2 from two dogs with urinary tract infections

Corynebacterium group D2 was isolated from two dogs with urinary tract infections. The isolates were resistant in vitro to all tested antibacterial drugs except vancomycin. One dog was successfully treated with this antibiotic, while the other died before treatment could be initiated.

Rhodococcus equi infection in patients with AIDS

Rhodococcus equi is an emerging opportunistic pathogen of HIV-I infected patients. It is an aerobic, Gram-positive coryneform bacterium which acts as a facultative intracellular micro-organism, multiplying in the phagosome of macrophages. Eighteen cases of R. equi infection in HIV-I positive patients have now been reported. Sixteen of these had pneumonia, of which 12 had cavitating lung lesions. A history of contact with farm animals, which are the primary hosts of R. equi, was found in only three patients. There was a delay in establishing a definite diagnosis in most cases as this depended upon the isolation of R. equi from sputum, bronchoalveolar lavage fluid, or blood. Treatment included surgical resection in five patients and erythromycin with a second antibiotic in 13 cases, but II of the 18 patients died from the infection. In this report we describe our experience of R. equi pneumonia in two AIDS patients and review the published cases of the disease in man.

Struvite stone formation by Corynebacterium group F1: a case report

Struvite stones are caused by urea-splitting, usually gram-negative, organisms. A case of aggressive struvite stone production caused by Corynebacterium group F1 is reported that responded to the appropriate antibiotic treatment. To our knowledge this organism has never been associated previously with struvite stone formation.

A numerical analysis of ribosomal RNA gene patterns for typing clinical isolates of Corynebacterium group D2

Restriction digest fragments of DNA from 46 clinical isolates identified as Corynebacterium group D2, were separated by electrophoresis, Southern blotted onto nylon membranes and hybridized to a ribosomal RNA gene probe. The resulting band patterns were subjected to unweighed pair-group cluster analysis. Representative strains from the main clusters were compared with similarly prepared band patterns from type strains of human Corynebacterium species. The results indicate that strains identified as Corynebacterium group D2 represent a unique taxon and that computer-assisted analysis of rRNA gene restriction fragment polymorphism (ribotyping) could be a useful technique in epidemiological studies of these bacteria.

Comparative in vitro activity of the new glycopeptide SK&F 104662 against problematic gram-positive bacteria

The in vitro activity of the new glycopeptide antibiotic SK&F 104662 against problematic gram-positive microorganisms was determined using the agar dilution technique. For comparison, ampicillin, oxacillin, vancomycin, erythromycin and gentamicin were tested. SK&F 104662 was found to have high activity against Staphylococcus aureus, coagulase-negative staphylococci (both methicillin sensitive and resistant strains), Enterococcus faecalis, Enterococcus faecium, Listeria monocytogenes, Corynebacterium jeikeium and Corynebacterium group D2. All of 254 isolates, except one vancomycin-resistant strain of Enterococcus faecium, were inhibited by 2 mg/l of SK&F 104662; this compound may thus be potentially useful in the treatment of infections with the above-mentioned gram-positive pathogens.

Corynebacterium minutissimum infection

Two cases of infection due to Corynebacterium minutissimum are described. On the basis of biochemical tests the organisms were thought at first to be Corynebacterium jeikeium. Methods of distinguishing between these species and the role of C. minutissimum in the pathogenesis of erythrasma and other skin infections are discussed.