Differentiation of Moraxella nonliquefaciens, M. lacunata, and M. bovis by using multilocus enzyme electrophoresis and hybridization with pilin-specific DNA probes.

Genetic relationships among strains of Moraxella nonliquefaciens, M. lacunata, and M. bovis were studied by using multilocus enzyme electrophoresis and DNA-DNA hybridization. The 74 isolates analyzed for electrophoretic variation at 12 enzyme loci were assigned to 59 multilocus genotypes. The multilocus genotypes were grouped in four major clusters, one representing strains of M. nonliquefaciens, two representing strains of M. lacunata, and one comprising strains of M. bovis and the single strain of M. equi analyzed. DNA-DNA hybridization with total genomic probes also revealed four major distinctive entities that corresponded to those identified by multilocus enzyme electrophoresis. The two distinct clusters recognized among the M. lacunata strains apparently corresponded to the species previously designated M. lacunata and M. liquefaciens. Distinction of the four entities was improved by hybridization with polymerase chain reaction products of nonconserved parts of pilin genes as DNA probes. With these polymerase chain reaction probes, new isolates of M. nonliquefaciens, M. lacunata, M. liquefaciens, and M. bovis can be identified easily by hybridization.     

Serological cross-reactions between Bartonella and Chlamydia species: implications for diagnosis.

Diagnosis of Chlamydia or Bartonella infections continues to rely mainly on serology. However, serological cross-reactions between members of these genera have recently been described. Sera from eight patients originally diagnosed as having Chlamydia pneumoniae endocarditis reacted with both Chlamydia sp. and Bartonella quintana antigens (microimmunofluorescence technique). Adsorption of sera with B. quintana or C. pneumoniae antigens removed anti-C. pneumoniae antibodies, whereas adsorption with C. pneumoniae antigens did not change antibody titers to B. quintana. Western blot analysis confirmed the presence of cross-reacting antigens and showed antibody patterns in all sera to be compatible with a Bartonella infection. These patients were therefore probably suffering from Bartonella-induced rather than Chlamydia-induced endocarditis. In contrast, sera from 10 patients presumed to be suffering from C. pneumoniae pneumonia did not display anti-B. quintana antibodies, although cross-reacting antigens were revealed by Western blotting. This work highlights the possibility that cases of infective Bartonella endocarditis are erroneously diagnosed as chlamydial infections.     

Combined genetic transformation and nutritional assay for identification of Moraxella nonliquefaciens.

A combined genetic transformation and nutritional assay is described that permits definitive identification of clinically isolated strains of Moraxella nonliquefaciens. Crude DNA preparations of strains of various Moraxella species were used to transform nutritional mutants of a stably competent strain of M. nonliquefaciens for ability to grow on a defined medium (Mn-B). DNA samples from 24 independently isolated strains of M. nonliquefaciens all resulted in massive (4+) transformation of each of two mutant assay strains. DNA samples from strains of M. bovis and M. lacunata frequently gave weak (1+) transformation of one of the mutant assay strains (Mn64) but almost always failed to transform another assay strain (Mn136). DNA samples from eight other Moraxella species failed completely to transform either of the mutant assay strains. When streaked on the defined medium used for the transformation assay (Mn-B), 23 of the 24 strains of M. nonliquefaciens grew well, but all strains of M. bovis and M. lacunata failed to grow on this medium.     

Cultural and chemical characterization of CDC groups EO-2, M-5, and M-6, Moraxella (Moraxella) species, Oligella urethralis, Acinetobacter species, and Psychrobacter immobilis.

We determined phenotypic characteristics, cellular fatty acid composition, and isoprenoid quinone content of representative strains of CDC groups EO-2, M-5, and M-6, Moraxella (Moraxella) species, Oligella urethralis, Acinetobacter species, and Psychrobacter immobilis. All organisms contained ubiquinone with eight isoprene units as the major isoprenolog, but distinct differences were observed in fatty acid composition. Twenty-eight of the original collection of CDC group EO-2 strains were further identified as P. immobilis, EO-2, or EO-3 by distinctive cellular fatty acid profiles, cellular morphology, and pigment production. The cellular fatty acid compositions of M-5 and M-6 were similar but were clearly different from those of other organisms. The genus Acinetobacter was differentiated from other organisms in the study by small amounts of 2-hydroxydodecanoic acid (2-OH-12:0), and P. immobilis was differentiated by small amounts of decanoic acid (10:0) and a branched-chain 17-carbon acid (i-17:0). All Moraxella species were distinguished by small amounts of decanoic acid (10:0) and the absence of i-17:0. M. bovis, M. nonliquefaciens, and some strains of M. lacunata formed a single fatty acid group, while M. osloensis, M. phenylpyruvica, M. atlantae, and other strains of M. lacunata (M. lacunata II) had species-specific fatty acid profiles. O. urethralis differed from Moraxella species by the presence of large amounts (49%) of cis-vaccenic acid (18:1 omega 7c), small amounts (1%) of 3-hydroxyhexadecanoate (3-OH-16:0), and the absence of 10:0 and 3-hydroxydodecanoate (3-OH-12:0). The combined use of chemical data and a small number of conventional tests permitted rapid identification and differentiation of these organisms from each other and from related organisms.     

Study on the usefulness of hypertonic culture media.

Specimens from 300 patients were studied using five to nine aerobic and anaerobic culture media, including five that were hypertonic, Groups studied included fever of unknown origin, suspected endocarditis, endocarditis during therapy, bacteremia during therapy, abscess and cellulitis, presumed infectious arthritis, renal transplantation during rejection, collagen disease, sarcoidosis, lymphoma, and colitis. Isolates in hypertonic media were reverted to parent form by agar passage. In only 5% of these selected cases were organisms found in hypertonic, but not conventional, media that appeared on the basis of repeated isolation and/or serological studies to come from the patient. Nine of the 16 appeared to be of major significance. The two groups in which use of highly enriched, hypertonic media seemed most helpful were suspected endocarditis and undefined meningitis with negative cultures using standard media. The most effective of the hypertonic media used was 0.3 M sucrose in brain heart infusion with 20% horse serum. In most instances, the organism grew only in the hypertonic sucrose, and in most cases it appeared in conventional rather than aberrant form. Hypertonic media, especially 0.3 M sucrose, are of substantial helpin a small number of carefully selected cases.     

Candida tropicalis causing prosthetic valve endocarditis

The incidence of endocarditis produced by the so-called "opportunists" as a complication of prosthetic valve surgery is progressively increasing in frequency and gradually transforming the clinical picture habitually associated with this disease. Candida endocarditis is an unusual but severe complication caused by Candida albicans or other fungal species. This case and a review of the literature indicate that Candida endocarditis treated with amphotericin B and prosthetic valve replacement may recur months after treatment, and that late recurrent Candida endocarditis, which is difficult to diagnose and treat, may be best prevented by lifelong antifungal suppressive therapy.     

Gonococcal endocarditis: a case report and literature review

Gonococcal endocarditis is rarely encountered in the post-antibiotic era. This case report describes a case of a previously healthy male who presented with double quotidian fever, chills, cough, and urethral symptoms. The presence of a cardiac mitral valvular vegetation along with positive blood cultures for Neisseria gonorrhoeae were diagnostic for gonococcal endocarditis. This case was, to our knowledge, the first reported gonococcal endocarditis case in China.     

Conventional viral cultures and shell vial assay for diagnosis of apparently culture-negativeCoxiella burnetii endocarditis

A patient with culture-negative endocarditis was diagnosed with Q fever endocarditis based on the results of serological tests and positive leukocyte cultures obtained using conventional viral cultures and the shell vial technique. This case report suggests that isolation ofCoxiella burnetii from blood may allow better diagnostic and therapeutical evaluation of patients with Q fever endocarditis. The use of both conventional and shell vial viral cultures is recommended for the isolation ofCoxiella burnetii from the blood of patients with apparently culture-negative endocarditis.     

Megasphaera elsdenii endocarditis.

A case of endocarditis caused by Megasphaera elsdenii is reported. This anaerobic grim-negative coccus has rarely been associated with human infections and has not previously been described as a cause of endocarditis.     

Detection of circulating antigen in experimental Candida albicans endocarditis by an enzyme-linked immunosorbent assay.

A double-antibody sandwich enzyme-linked immunosorbent assay was developed for the detection of circulating Candida albicans antigen during the course of experimental C. albicans endocarditis. The enzyme-linked immunosorbent assay was positive in 75% of rabbits with polyethylene catheter-induced experimental aortic valve C. albicans endocarditis but was negative in all controls, including catheterized animals that received intravenous Candida or catheterized but uninfected animals, and in rabbits with experimental fungal or bacterial endocarditis of other etiologies. The enzyme-linked immunosorbent assay was much more sensitive than blood culturing or fever determinations in experimental C. albicans endocarditis. This assay is more sensitive than currently available serological techniques, is highly specific, and deserves further study in the diagnosis of invasive, disseminated C. albicans infections, including endocarditis.     

Differentiation of some species of Neisseriaceae and other bacterial groups by DNA-DNA hybridization

DNA-DNA hybridization using total genomic DNA probes may represent a way of differentiating between miscellaneous bacterial species. This was studied with type and reference strains of 20 species in Moraxella, Kingella, and other selected Gram-negative groups. Both radioactive and biotin labelling were employed. Most of the species examined were easily distinguished, such as Moraxella (Branhamella) catarrhalis, M.(B.) ovis, M. atlantae, M. phenylpyruvica, M. osloensis, Neisseria elongata, N. meningitidis, Kingella kingae, K. indologenes, K. dentrificans, Oligella urethralis, Eikenella corrodens, Cardiobacterium hominis, Haemophilus aphrophilus, Actinobacillus actinomycetemcomitans, Gardnerella vaginalis, and DF-2. This reflected the extent of the genetic distances between them as a basis for identification by hybridization. There was some clustering in the Moraxella group. Especially the closely related Moraxella nonliquefaciens, M. lacunata and M. bovis showed strong hybridization affinities. This leads to potential problems in distinguishing these three species from each other by DNA-DNA hybridization with total genomic probes alone.     

Identification of Streptococcus sanguinis genes required for biofilm formation and examination of their role in endocarditis virulence

Streptococcus sanguinis is one of the pioneers in the bacterial colonization of teeth and is one of the most abundant species in the oral biofilm called dental plaque. S. sanguinis is also the most common viridans group streptococcal species implicated in infective endocarditis. To investigate the association of biofilm and endocarditis, we established a biofilm assay and examined biofilm formation with a signature-tagged mutagenesis library of S. sanguinis. Four genes that have not previously been associated with biofilm formation in any other bacterium, purB, purL, thrB, and pyrE, were putatively identified as contributing to in vitro biofilm formation in S. sanguinis. By examining 800 mutants for attenuation in the rabbit endocarditis model and for reduction in biofilm formation in vitro, we found some mutants that were both biofilm defective and attenuated for endocarditis. However, we also identified mutants with only reduced biofilm formation or with only attenuation in the endocarditis model. This result indicates that the ability to form biofilms in vitro is not associated with endocarditis virulence in vivo in S. sanguinis.     

Native valve endocarditis due to Enterococcus hirae

Enterococcus hirae is a rare isolate in clinical specimens. We describe a case of native aortic-valve endocarditis that was caused by Enterococcus hirae in a 72-year-old man. This is the first reported case of endocarditis due to this organism.     

Corynebacterium jeikeium endocarditis: a systematic overview spanning four decades

Skin flora is an important source of microorganisms that cause infective endocarditis. While staphylococcal and beta-hemolytic streptococcal species are well-recognized components of skin flora that can cause infective endocarditis, other skin flora rarely produce endocardial infection. One species of Corynebacterium has received the most attention, Corynebacterium jeikeium. This bacterium, a gram-positive rod that is a strict aerobe, is known to cause mechanical prosthetic valve infection and vancomycin is generally required for treatment of this multidrug-resistant organism. Following treatment of an unusual case of bioprosthetic valve endocarditis due to C. jeikeium, a Medline search for English-language articles published from January 1966 to October 2004 was performed. Reports of C. jeikeium endocarditis cases with culture of either blood or cardiac surgery tissue samples positive for C. jeikeium and with clinical and echocardiographic findings of infective endocarditis were reviewed. Clinical data and results of diagnostic procedures were examined. All 38 patients with C. jeikeium endocarditis reported in the literature had at least one predisposing condition for the development of infective endocarditis. The majority of patients (74%) had involvement of a prosthetic heart valve. The mortality attributed to C. jeikeium endocarditis was 33% and was similar in patients who did and did not undergo valve replacement. This relatively high mortality rate mandates that clinicians be aware of this rare endocardial infection. C. jeikeium is a rare cause of endocarditis and it more commonly infects prosthetic valves. Careful scrutiny is required when C. jeikeium is isolated from a blood culture, particularly in patients with underlying prosthetic cardiac valves.     

Fatal case of endocarditis due to Weissella confusa

This is the first reported case of endocarditis due to the Lactobacillus-like vancomycin-resistant gram-positive bacillus Weissella confusa. Full identification and susceptibility testing of Lactobacillus-like organisms recovered in blood culture should be performed for patients with clinical presentations that suggest endocarditis.     

Detection of fastidious bacteria in cardiac valves in cases of blood culture negative endocarditis

The diagnosis of blood culture negative endocarditis is still a problem. Fastidious bacteria such as bartonella and coxiella are responsible for cases of blood culture negative endocarditis, the identification of which is mainly based on serological and DNA studies only available in specialised centres. Therefore, a routine technique is needed in surgical pathology laboratories to detect these bacteria in cardiac valve tissue sections. This report describes a staining technique, the Gimenez stain, feasible and sensitive in detecting bartonella and coxiella in two cases of blood culture negative endocarditis.     

Pathogenesis of infective endocarditis

The present knowledge of epidemiology, microbiology and pathogenesis of infective endocarditis in both native valve and prosthetic valve endocarditis is described. An attempt has been made to discuss early events in its pathogenesis. This understanding may help in the prevention and management strategies.     

Prosthetic Valve Endocarditis Caused by Mycoplasma hominis

 Mycoplasma hominis endocarditis is extremely uncommon and difficult to diagnose. Atypical growth characteristics in routine bacterial culture and an inability to demonstrate the organism using Gram staining can lead to a delayed diagnosis of Mycoplasma hominis infections, and the organism is often missed. This report describes a patient with Mycoplasma hominis prosthetic valve endocarditis. The microorganism was recovered from the mitral prosthesis but was missed in blood cultures. This finding suggests that Mycoplasma hominis should be considered in the differential diagnosis of culture-negative endocarditis.     

Diagnosing endocarditis with the cloned 112 kDa antigen of Enterococcus faecalis

A new indirect ELISA is presented for the diagnosis of enterococcal endocarditis. It is based on the cloning of Enterococcus faecalis DNA into lambda gt11. The library was screened by antisera from three cases of E. faecalis endocarditis. Three positive clones were found, all of which cross-reacted with the 112 kDa antigen of E. faecalis. One of these was taken and lysogenised into E. coli Y1089 to produce a fusion protein of 125 kDa. This IPTG dependent protein was purified by affinity chromatography and used in an indirect ELISA. The test differentiated between five cases of enterococcal endocarditis (IgG ELISA optical density greater than 0.8) and patients with endocarditis due to staphylococci (IgG ELISA optical density less than 0.243) and other streptococci (IgG ELISA optical density less than 0.656). Patients with a simple E. faecalis septicaemia had a maximum IgG ELISA optical density of 0.636. The only major cross-reaction occurred in patients with Streptococcus bovis endocarditis.     

Corynebacterium CDC Group A-4 native valve endocarditis

A patient with endocarditis caused byCorynebacterium CDC Group A-4 is described. This is the first case in the literature of endocarditis caused by this bacteria, and is unique in that the patient was immune competent and the infection occurred on a native valve. This case illustrates that corynebacteria cannot be considered a contaminant and that the exact pathogen should be identified.