16S rRNA sequences of Bartonella bacilliformis and cat scratch disease bacillus reveal phylogenetic relationships with the alpha-2 subgroup of the class Proteobacteria

Hemin binding protein C is found in outer membrane vesicles and protects Bartonella henselae against toxic concentrations of hemin

Bartonella species are gram-negative, emerging bacterial pathogens found in two distinct environments. In the gut of the obligately hematophagous arthropod vector, bartonellae are exposed to concentrations of heme that are toxic to other bacteria. In the bloodstream of the mammalian host, access to heme and iron is severely restricted. Bartonellae have unusually high requirements for heme, which is their only utilizable source of iron. Although heme is essential for Bartonella survival, little is known about genes involved in heme acquisition and detoxification. We developed a strategy for high-efficiency transposon mutagenesis to screen for genes in B. henselae heme binding and uptake pathways. We identified a B. henselae transposon mutant that constitutively expresses the hemin binding protein C (hbpC) gene. In the wild-type strain, transcription of B. henselae hbpC was upregulated at arthropod temperature (28°C), compared to mammalian temperature (37°C). In the mutant strain, temperature-dependent regulation was absent. We demonstrated that HbpC binds hemin and localizes to the B. henselae outer membrane and outer membrane vesicles. Overexpression of hbpC in B. henselae increased resistance to heme toxicity, implicating HbpC in protection of B. henselae from the toxic levels of heme present in the gut of the arthropod vector. Experimental inoculation of cats with B. henselae strains demonstrated that both constitutive expression and deletion of hbpC affect the ability of B. henselae to infect the cat host. Modulation of hbpC expression appears to be a strategy employed by B. henselae to survive in the arthropod vector and the mammalian host.

Rapid polymerase chain reaction-based confirmation of cat scratch disease and Bartonella henselae infection

CONTEXT

Cat scratch disease (CSD) commonly occurs secondary to Bartonella henselae infection, and the diagnosis has traditionally been made by microscopic findings, the identification of organisms by cytochemistry, and clinical history. However, cytochemical analysis tends to be very difficult to interpret, and histology alone may be insufficient to establish a definitive diagnosis of CSD.

OBJECTIVE

To demonstrate the presence of B henselae in tissue suspected of involvement by CSD, using a novel polymerase chain reaction (PCR) assay.

DESIGN

Isolates of B henselae (American Tissue Culture Collection 49793) and Afipia felis (American Tissue Culture Collection 49714) were cultured on blood agar and buffered charcoal yeast extract agar, respectively. DNA was isolated from these organisms and from formalin-fixed, paraffin-embedded tissue sections with involvement by CSD (8 patients). Negative controls included water, human placental tissue, and lymph node specimens from 6 patients with reactive lymphoid hyperplasia and from 2 patients with granulomatous lymphadenitis. A primer complementary to B henselae citrate synthase gltA gene sequence was designed to perform a seminested PCR amplification. For restriction fragment length polymorphism analysis, PCR products were digested by TaqI restriction enzyme and analyzed by gel electrophoresis.

RESULTS

Seminested PCR analysis of the cultured isolates of B henselae, but not of A felis, showed specific amplification. However, nonnested PCR did not provide consistently positive results in tissue sections with CSD. Therefore, we used a seminested PCR, which revealed positivity in all of the cases with clinicopathologic diagnoses of CSD. None of the negative controls showed positivity. Restriction enzyme provided confirmation of the specific PCR amplification of the B henselae sequence.

CONCLUSIONS

Since the amplification product has a low molecular size (<200 base pairs), this assay is useful for detection of B henselae in formalin-fixed, paraffin-embedded tissues. The seminested PCR protocol described here can be used for rapid and reliable confirmation of B henselae in samples that are histologically suggestive of CSD.

Characterization of the ftsZ gene from Ehrlichia chaffeensis, Anaplasma phagocytophilum, and Rickettsia rickettsii, and use as a differential PCR target

Degenerate primers corresponding to highly conserved regions of previously characterized ftsZ genes were used to PCR amplify a portion of the ftsZ gene from the genomic DNA of Ehrlichia chaffeensis (ftsZ(Ech)), Anaplasma phagocytophilum (ftsZ(Ap)), and Rickettsia rickettsii (ftsZ(Rr)). Genome walking was then used to amplify the 5' and 3' termini of the genes. The DNA sequences of the resulting amplification products yielded open reading frames coding for proteins with molecular masses of 42.0, 45.7, and 48.3 kDa for A. phagocytophilum, E. chaffeensis, and R. rickettsii, respectively. These homologs are 20 to 70 amino acids longer than the FtsZ proteins characterized in bacteria such as Escherichia coli and Bacillus subtilis, but do not possess the large extended carboxyl-termini found in the FtsZ proteins of Bartonella, Rhizobium, and Agrobacterium species. The functional domains important for FtsZ activity are conserved within the ehrlichial and rickettsial FtsZ protein sequences. The R. rickettsii FtsZ sequence is highly homologous to the FtsZ protein previously described for Rickettsia prowazekii (89% identity), and identical to the FtsZ protein of Rickettsia conorii. The percent identity observed between the A. phagocytophilum and E. chaffeensis FtsZ proteins is only 79% and is particularly low in the carboxyl-terminal region (15.8% identity). Primers were designed to PCR amplify a portion of the variable carboxyl-terminal region of the ftsZ gene, and used to differentiate each agent based on the size of the amplicons: A. phagocytophilum, 278 bp; E. chaffeensis, 341 bp; and Rickettsia spp., 425 bp.

The gene encoding the 17-kDa antigen of Bartonella henselae is located within a cluster of genes homologous to the virB virulence operon

A Bartonella henselae genomic A library was screened with antiserum generated in mice against live B. henselae. One of the immunoreactive clones expressed a 17-kDa antigen that was characterized previously as an immunodominant protein of B. henselae. Sequence analysis of the recombinant clone, pBHIM-2, revealed that the open reading frame (ORF) encoding the 17-kDa antigen was situated between homologs of virB4 and virB6, two genes that belong to the virB operon. The virB operon has been associated with the transfer of oncogenic T-DNA in Agrobacterium tumefaciens and with secretion of the pertussis toxin in Bordetella pertussis. Downstream of the virB6 gene within pBHIM-2 was a partial open reading frame that was homologous to the virB8 gene. Rescreening of the library by plaque hybridization using probes specific to the 5' and 3' ends of the pBHIM-2 insert resulted in the isolation of recombinant clones containing additional virB genes. Assembly of the sequences obtained from the recombinant clones revealed that eight of the open reading frames encode homologs of the VirB proteins. The homology and colinearity with the virB genes suggest that the gene encoding the 17-kDa antigen is expressed within the virB locus of B. henselae.

Sonicated diagnostic immunoblot for bartonellosis

Two simple Bartonella bacilliformis immunoblot preparation methods were developed. Antigen was prepared by two different methods: sonication of whole organisms or glycine extraction. Both methods were then tested for sensitivity and specificity. Well-defined control sera were utilized in the development of these diagnostic immunoblots, and possible cross-reactions were thoroughly examined. Sera investigated for cross-reaction with these diagnostic antigens were drawn from patients with brucellosis, chlamydiosis, Q fever, and cat scratch disease, all of whom were from regions where bartonellosis is not endemic. While both immunoblots yielded reasonable sensitivity and high specificity, we recommend the use of the sonicated immunoblot, which has a higher sensitivity when used to detect acute disease and produces fewer cross-reactions. The sonicated immunoblot reported here is 94% sensitive to chronic bartonellosis and 70% sensitive to acute bartonellosis. In a healthy group, it is 100% specific. This immunoblot preparation requires a simple sonication protocol for the harvesting of B. bacilliformis antigens and is well suited for use in regions of endemicity.

Afipia clevelandensis antibodies and cross-reactivity with Brucella spp. and Yersinia enterocolitica O:9

Afipia clevelandensis is a recently described gram-negative bacterium whose potential pathogenic role in human disease is under investigation. Only one strain, from the pretibial lesion of a patient hospitalized with necrotizing pancreatitis for 5 months, has been isolated. Using an indirect immunofluorescence assay to detect anti-A. clevelandensis antibodies, we found a seroprevalence of 1.5% among 30,194 sera routinely submitted for laboratory diagnosis of rickettsial diseases. However, among the 52 patients who were clinically evaluable and who exhibited detectable antibodies against A. clevelandensis, 42% were eventually diagnosed as certainly or probably having brucellosis and 15% were eventually diagnosed as certainly or probably having Yersinia enterocolitica O:9 infection, which is the serotype most often encountered in Europe. Western immunoblotting and cross-adsorption tests showed that an 11.5-kDa proteinase K-labile band and a 21-kDa proteinase-stable band, presumably lipopolysaccharide, were responsible for cross-reactivity among A. clevelandensis, Brucella abortus, and Y. enterocolitica O:9. Other diagnoses included nosocomial infections and various community-acquired diseases for which the role of A. clevelandensis remains undefined. Physicians and clinical microbiologists should be aware of this cross-reactivity in future assessments of the role of A. clevelandensis in human pathology.

Current knowledge of Bartonella species

Bartonella species are now considered emerging pathogens. Of the 11 currently recognized species, four have been implicated in human disease, although only two have been encountered in Europe. Bartonella quintana infections are now being diagnosed among the urban homeless and deprived, manifesting as trench fever, and Bartonella henselae has been shown to be the causative agent of cat scratch disease. Both species also cause a variety of HIV-associated infections, including bacillary anglomatosis. However, perhaps the most significant presentation of bartonellae infection is culture-negative endocarditis. The epidemiologies of Bartonella infections are poorly understood; most Bartonella henselae infections are probably acquired from infected cats, either directly by contact with a cat or indirectly via fleas. No animal reservoir has been implicated for Bartonella quintana; however, infection can be transmitted via the human body louse. Diagnosis of Bartonella infections can be made using histological or microbiological methods. The demonstration of specific antibodies may be useful in some instances, although certainly not in all. Cultivation of Bartonella is difficult, as the bacteria are extremely fastidious. Polymerase chain reaction-based or immunological methods for the detection of bartonella in infected tissues have proven useful. Clinical relapse is often associated with Bartonella infections despite a wide range of prescribed regimens. Only aminoglycosides display in vitro bactericidal activity against intracellular Bartonella species; therefore, they are recommended for treatment of Bartonella infections.

The 75-kilodalton antigen of Bartonella bacilliformis is a structural homolog of the cell division protein FtsZ

A genomic library of Bartonella bacilliformis was constructed and screened with human anti-Bartonella serum from a patient with the chronic, verruga peruana phase of bartonellosis. An immunoreactive clone isolated from this library was found to code for a 591-amino-acid protein with a high degree of sequence similarity to the FtsZ family of proteins. The degree of amino acid identity between the B. bacilliformis protein (FtsZ[Bb]) and the other FtsZ proteins is especially pronounced over the N-terminal 321 amino acids (N-terminal domain) of the sequence, with values ranging from 45% identity for the homolog from Micrococcus luteus (FtsZ[Ml]) to 91% identity for the homolog from Rhizobium melliloti, (FtsZ[Rm1]). All of the functional domains required for FtsZ activity are conserved in FtsZ(Bb) and are located within the N-terminal domain of the protein. FtsZ(Bb) is approximately twice as large as most of the other FtsZ proteins previously reported, a property it shares with FtsZ(Rm1). Like the Rhizobium homolog, FtsZ(Bb) has a C-terminal region of approximately 256 amino acids that is absent in the other FtsZ proteins. Evidence is presented that implicates this region in the protein's antigenicity and suggests that, unlike most other FtsZ homologs, FtsZ(Bb) is at least partly exposed at the cell surface. PCR analysis revealed that an ftsZ gene similar in size to the B. bacilliformis gene is present in Bartonella henselae, a bacterium that is closely related to B. bacilliformis.

Bartonella spp. as emerging human pathogens

Members of the genus Bartonella (formerly Rochalimaea) were virtually unknown to modern-day clinicians and microbiologists until they were associated with opportunistic infections in AIDS patients about 6 years ago. Since that time, Bartonella species have been associated with cat scratch disease, bacillary angiomatosis, and a variety of other disease syndromes. Clinical presentation of infection with Bartonella ranges from a relatively mild lymphadenopathy with few other symptoms, seen in cat scratch disease, to life-threatening systemic disease in the immunocompromised patient. In some individuals, infection manifests as lesions that exhibit proliferation of endothelial cells and neovascularization, a pathogenic process unique to this genus of bacteria. As the spectrum of disease attributed to Bartonella is further defined, the need for reliable laboratory methods to diagnose infections caused by these unique organisms also increases. A brief summary of the clinical presentations associated with Bartonella infections is presented, and the current status of laboratory diagnosis and identification of these organisms is reviewed.

Bartonella bacilliformis: dangerous pathogen slowly emerging from deep background

Bartonella bacilliformis was perhaps the most lethal bacterial human pathogen in the pre-antibiotic era, but infections were and are limited to a specific geographical area, largely in Peru, corresponding to the range of its sand fly vector. B. bacilliformis targets both red cells and endothelial cells. Recent phylogenetic realignments have revealed a close genetic relationship to other bacteria which cause human diseases, including bacterial angiomatosis, to the former Grahamella species which infect red cells in other mammals, and to plant pathogens and symbionts including Agrobacterium tumefaciens and Rhizobium meliloti. Features of B. bacilliformis that contribute to its pathogenesis are slowly coming into view, and are here reviewed.

Will the real agent of cat-scratch disease please stand up?

Cat-scratch disease has been recognized since 1889 in association with the oculoglandular syndrome of Parinaud. The epidemiologic association with cats was first made in 1931 and further substantiated throughout the years, refining the interaction predominantly to kittens. Putative infectious agents have included numerous species of bacteria, chlamydiae, and viruses. The cultivation of Afipia spp. in the late 1980s appeared to answer the mystery of the identity of the agent. However, even more recent analysis, which has combined traditional microbiology, molecular methods, and additional epidemiology, has demonstrated that Bartonella (Rochalimaea) henselae is the definitive agent of cat-scratch disease. Our understanding of the pathogenesis of cat-scratch disease and other diseases caused by Bartonella species is incomplete and the spectrum of diseases continues to emerge. We review historic and modern efforts to understand the etiology of cat-scratch disease and related syndromes.

Bartonella (Rochalimaea) quintana infections

Bartonella (formerly Rochalimaea) quintana is the etiological agent of trench fever, a disease extensively reported during the World Wars. Recent molecular biology approaches have allowed dramatic extension of the spectrum of Bartonella infections. B. quintana is now also recognized as an etiological agent of fever and bacteremia, endocarditis, bacillary angiomatosis, and chronic lymphadenopathy. Human immunodeficiency virus-infected patients and/or homeless people are the most vulnerable to infection. Poverty and louse infestation were the main epidemiological factors associated with B. quintana infections during wartime. Although poverty and chronic alcoholism have been associated with modern cases of trench fever and bacteremia due to B. quintana in Europe and the United States, vectors for B. quintana have not been clearly identified and B. quintana has not been isolated from modern-day lice. Microscopic bacillary angiomatosis lesions are characterized by tumor-like capillary lobules, with proliferating endothelial cells. In vitro experiments have shown that B. quintana survives within endothelial cells and stimulates cell proliferation. These observations, together with the finding that lesions may regress when antibiotic therapy is administered, strongly suggest that B. quintana itself stimulates angiogenesis. Bartonella infections are characterized by a high frequency of relapses after brief courses of antibiotic therapy. It is to be noted that in vitro, although Bartonella species are highly susceptible to antibiotics, only the aminoglycosides have proved to be bactericidal. However, the most effective antibiotic regimen for Bartonella infections remains to be established.

Physical map of the Bartonella bacilliformis genome

The genome of Bartonella bacilliformis was shown to be a single circular DNA molecule of about 1,600 kbp having six NotI, four SfiI, and two CeuI sites. A physical map of the DNA was constructed by contour-clamped homogeneous electric field pulsed-field gel electrophoresis of DNA restriction fragments. rRNA operons, the invasion-associated locus, and a flagellin gene were located on the map by hybridization.

Genetic and phenetic analyses of Bradyrhizobium strains nodulating peanut (Arachis hypogaea L.) roots

Seventeen Bradyrhizobium sp. strains and one Azorhizobium strain were compared on the basis of five genetic and phenetic features: (i) partial sequence analyses of the 16S rRNA gene (rDNA), (ii) randomly amplified DNA polymorphisms (RAPD) using three oligonucleotide primers, (iii) total cellular protein profiles, (iv) utilization of 21 aliphatic and 22 aromatic substrates, and (v) intrinsic resistances to seven antibiotics. Partial 16S rDNA analysis revealed the presence of only two rDNA homology (i.e., identity) groups among the 17 Bradyrhizobium strains. The partial 16S rDNA sequences of Bradyrhizobium sp. strains form a tight similarity (> 95%) cluster with Rhodopseudomonas palustris, Nitrobacter species, Afipia species, and Blastobacter denitrificans but were less similar to other members of the alpha-Proteobacteria, including other members of the Rhizobiaceae family. Clustering the Bradyrhizobium sp. strains for their RAPD profiles, protein profiles, and substrate utilization data revealed more diversity than rDNA analysis. Intrinsic antibiotic resistance yielded strain-specific patterns that could not be clustered. High rDNA similarity appeared to be a prerequisite, but it did not necessarily lead to high similarity values between RAPD profiles, protein profiles, and substrate utilization. The various relationship structures, coming forth from each of the studied features, had low compatibilities, casting doubt on the usefulness of a polyphasic approach in rhizobial taxonomy.

Expression of tfx and sensitivity to the rhizobial peptide antibiotic trifolitoxin in a taxonomically distinct group of alpha-proteobacteria including the animal pathogen Brucella abortus

Three phylogenetically distinct groups within the alpha-proteobacteria which differ in trifolitoxin sensitivity are described. Trifolitoxin sensitivity was found in strains of Agrobacterium, Brucella, Mycoplana, Ochrobactrum, Phyllobacterium, Rhodobacter, Rhodopseudomonas, Rhodospirillum, and Rhizobium. Strains of Agrobacterium, Brucella, Phyllobacterium, Rhizobium, and Rhodospirillum were capable of producing trifolitoxin upon conjugal transfer of tfxABCDEFG.

Evolutionary relationships among ammonia- and nitrite-oxidizing bacteria

Comparative 16S rRNA sequencing was used to evaluate phylogenetic relationships among selected strains of ammonia- and nitrite-oxidizing bacteria. All characterized strains were shown to be affiliated with the proteobacteria. The study extended recent 16S rRNA-based studies of phylogenetic diversity among nitrifiers by the comparison of eight strains of the genus Nitrobacter and representatives of the genera Nitrospira and Nitrospina. The later genera were shown to be affiliated with the delta subdivision of the proteobacteria but did not share a specific relationship to each other or to other members of the delta subdivision. All characterized Nitrobacter strains constituted a closely related assemblage within the alpha subdivision of the proteobacteria. As previously observed, all ammonia-oxidizing genera except Nitrosococcus oceanus constitute a monophyletic assemblage within the beta subdivision of the proteobacteria. Errors in the 16S rRNA sequences for two strains previously deposited in the databases by other investigators (Nitrosolobus multiformis C-71 and Nitrospira briensis C-128) were corrected. Consideration of physiology and phylogenetic distribution suggested that nitrite-oxidizing bacteria of the alpha and gamma subdivisions are derived from immediate photosynthetic ancestry. Each nitrifier retains the general structural features of the specific ancestor's photosynthetic membrane complex. Thus, the nitrifiers, as a group, apparently are not derived from an ancestral nitrifying phenotype.

Characterization of hemagglutinating components on the Anaplasma marginale initial body surface and identification of possible adhesins

Interaction of Anaplasma marginale initial bodies with the bovine erythrocyte surface was examined by a direct hemagglutination assay. Purified initial bodies were shown to specifically hemagglutinate bovine erythrocytes but not erythrocytes from nonhost animal species. Hemagglutination was inhibited by treatment of purified initial bodies with trypsin, alpha-chymotrypsin, or proteinase K but not by treatment with neuraminidase or sodium periodate. Treatment of bovine erythrocytes with alpha-chymotrypsin or neuraminidase partially inhibited hemagglutination of the treated cells by initial bodies. In contrast, no inhibition occurred after treatment of erythrocytes with trypsin, phospholipases, or sodium periodate or when monosaccharides and disaccharides were used as potential competitive inhibitors. Thus, the initial body receptor is probably a surface protein, whereas the bovine receptor may comprise both protein and carbohydrate. Hemagglutination was unaffected by treatment of initial bodies with monoclonal or polyclonal antibodies raised against the A. marginale 31-kDa (MSP4) major surface polypeptide or non-A. marginale proteins or by treatment with a monoclonal antibody to the A. marginale MSP1a neutralization-sensitive epitope. In contrast, antiserum raised against whole A. marginale initial bodies or monospecific antibodies raised against purified A. marginale major surface polypeptides with molecular sizes of 105 (MSP1a), 100 (MSP1b), 61, and 36 (MSP2) kDa completely or partially inhibited hemagglutination. These data confirm the proposed surface location of the proteins susceptible to inhibition and suggest that they mediate hemagglutination of bovine erythrocytes. We propose that these surface proteins are possible adhesins.

Characterization of the 16S-23S rRNA intergenic spacer of Bartonella bacilliformis

The 16S-23S intergenic spacer region from the ribosomal RNA (rRNA) operon of Bartonella bacilliformis was cloned and characterized. The spacer is 906 nucleotides (nt) in length and contains the genes encoding isoleucine-tRNA (tRNA(Ile)) and alanine-tRNA (tRNA(Ala)). The tRNA-encoding genes are separated by 122 nt and are centrally located in the 16S-23S spacer region, with approx. 300 flanking nt. Genes encoding tRNA(Ile) and tRNA(Ala) have 88.3 and 93.4% sequence identity, respectively, to the homologous genes of Rhodobacter sphaeroides.

Detection of Rochalimaea henselae DNA in specimens from cat scratch disease patients by PCR

A PCR assay was developed by using degenerate primers that allow amplification of a 414-bp fragment of DNA from the rickettsia-like organisms Rochalimaea henselae and R. quintana. Internal oligonucleotides were used as hybridization probes, permitting rapid differentiation of these two Rochalimaea species. DNAs from 12 different isolates of R. henselae were amplified with the PCR primers, and the resulting 414-bp PCR product hybridized only with the R. henselae-specific probe. DNAs from four different isolates of R. quintana were amplified and produced a PCR product of the same size that hybridized only with the R. quintana-specific probe. DNAs from isolates of R. elizabethae, R. vinsonii, Bartonella bacilliformis, and Afipia felis failed to amplify the 414-bp fragment in the PCR assay. This two-step assay was applied to DNAs extracted from 16 fresh (unfixed) lymph node biopsy specimens and nine aspirates from patients with clinical cat scratch disease (CSD) to assay for the presence of R. henselae or R. quintana DNA in these samples. Twenty-one (84%) of 25 lymph node samples from CSD patients were positive for R. henselae, while none were positive for R. quintana. The characteristic 414-bp fragment was not amplified from eight lymph node tissue samples from non-CSD cases. These results provide evidence that R. henselae, and not R. quintana, plays the central role in the etiology of CSD.

Taxonomic position of the rickettsiae: current knowledge

The term rickettsiae initially encompassed all intracellular bacteria. Early rickettsial taxonomy was based on a comparison of a few phenotypic characteristics and recently, molecular studies brought new bases for rickettsial taxonomy. All rickettsial species studied so far belong to the alpha and gamma groups of the Proteobacteria. Ehrlichiae complex groups Cowdria ruminantium, Anaplasma marginale and Wolbachia pipientis and the related parthenogenesis and cytoplasmic incompatibility bacteria, whereas Rochalimaea species group with Bartonella bacilliformis. Rickettsia tsutsugamushi may form an independent lineage, whereas molecular data allow to regroup serologically defined typhus and spotted fever group rickettsiae. The true scale of Rickettsia and Coxiella genera remain to be determined.

Characterization of the fMet initiator tRNA gene of Bartonella bacilliformis

A ribosomal RNA operon was cloned from the agent of human Oroya fever, Bartonella bacilliformis. The 3' end of the operon contains a 77-nucleotide (nt) N-formylmethionine (fMet) initiator tRNA-encoding gene with 100% sequence identity to the fMet tRNA-encoding gene of Rhodobacter sphaeroides. The 3' region downstream from the gene has an 8-nt inverted repeat and 28 contiguous direct repeats of the heptamer 5'-TTCTCTA. To date, B. bacilliformis and R. sphaeroides are the only known eubacteria which have an fMet tRNA-encoding gene within the 3' end of their rRNA operons.

Polymerase chain reaction-based restriction fragment length polymorphism analysis of a fragment of the ribosomal operon from Rochalimaea species for subtyping

Restriction endonuclease analysis of a polymerase chain reaction-amplified DNA fragment which included the spacer region between the genes coding for 16S and 23S rRNAs and a portion of the gene coding for 23S rRNA (spacer + 23S) was done on 10 previously characterized clinical isolates of Rochalimaea henselae, one clinical isolate of Rochalimaea quintana, and the type strains of R. henselae, R. quintana, Rochalimaea vinsonii, and Bartonella bacilliformis. Brucella abortus DNA was not amplified by the primer set used. The clinical isolates of Rochalimaea were obtained from blood or tissue from patients with and without preexisting disease. The amplicon from each strain was digested with five endonucleases (AluI, HaeIII, TaqI, HinfI, and MseI). AluI and HaeIII were useful in species differentiation and subtyping of R. henselae. R. henselae isolates showed six different restriction patterns with AluI and four patterns with HaeIII. TaqI, HinfI, and MseI were useful only in species differentiation. These observations indicate that PCR amplification of the spacer + 23S region of the ribosomal DNA of Rochalimaea spp., along with restriction endonuclease analysis, allows differentiation of Rochalimaea spp. from closely related genera, differentiation among the species within Rochalimaea, and differentiation of strains within R. henselae. The subtyping potential of this method may be useful for further clinical and epidemiologic studies of the spectrum of diseases caused by R. henselae.

Rochalimaea elizabethae sp. nov. isolated from a patient with endocarditis

A Rochalimaea-like organism (strain F9251) was isolated from a patient with endocarditis after blood drawn for culture before antimicrobial therapy was subcultured onto blood and chocolate agars and incubated for 2 weeks in 5% CO2. The strain was phenotypically similar to known Rochalimaea species. The cellular fatty acid composition of strain F9251 was close to but distinct from those of the three known Rochalimaea species and was most similar to that of R. vinsonii. Labeled DNA from strain F9251 was 59 to 67% related to DNAs from type strains of the three described Rochalimaea species, and its 16S rRNA gene sequence was 98.9% or more homologous to their 16S rRNA gene sequences. These findings support classification of F9251 as a new Rochalimaea species, for which the name Rochalimaea elizabethae sp. nov. is proposed. The patient infected with the organism had large bacterial vegetations on his aortic valve and was cured with antibiotics and valve-replacement surgery. Recognition of the procedures required to identify this and other Rochalimaea species suggests that clinical laboratories should prolong the incubation times of cultures of blood and tissue from patients with suspected endocarditis, patients with fever of unknown origin, and immunocompromised patients with fever so that the full spectrum of disease caused by these organisms can be recognized.

Isolation of Rochalimaea species from cutaneous and osseous lesions of bacillary angiomatosis

BACKGROUND

Bacillary angiomatosis is characterized by vascular lesions, which occur usually in patients infected with the human immunodeficiency virus (HIV). A newly described gram-negative organism, Rochalimaea henselae, has been associated with cutaneous bacillary angiomatosis, but no organism has been isolated and cultivated directly from cutaneous tissue.

METHODS

We used two methods to isolate the infecting bacterium from four HIV-infected patients with cutaneous lesions suggestive of bacillary angiomatosis: cultivation with eukaryotic tissue-culture monolayers and direct plating of homogenized tissue onto agar. The patients' blood was cultured with the lysis-centrifugation method. Isolates recovered from skin and blood were identified by sequencing all or part of the 16S ribosomal RNA gene amplified with the polymerase chain reaction.

RESULTS

R. quintana, historically known as the agent of trench fever, was isolated from cutaneous lesions in three patients, after tissue homogenates were cultivated with endothelial-cell monolayers; R. henselae was isolated from a cutaneous lesion in one patient. In two patients, R. quintana was isolated from both cutaneous tissue and blood; in one patient it was also isolated from bone.

CONCLUSIONS

In bacillary angiomatosis, either of two species of rochalimaea--R. quintana or R. henselae--can be isolated from cutaneous lesions or blood, providing an additional method of diagnosis.

Phylogenetic relationships among the agent of bacillary angiomatosis, Bartonella bacilliformis, and other alpha-proteobacteria

Bacillary angiomatosis (BA) and chronic bartonellosis are bacterial infections of humans which result in an unusual vascular proliferative tissue response. In order to determine their phylogenetic relationships, we have determined greater than 95% of the 16S rRNA sequences for these two organisms by amplification directly from infected BA tissue and from a Bartonella bacilliformis lyophilized culture. The BA agent and B. bacilliformis are closely related alpha-proteobacteria (98.5%), although the BA agent is more closely related to Rochalimaea quintana (99.1%). Contrary to previous belief, the BA agent is distinct from, and less closely related to, the cat scratch bacillus (Afipia felis) (90.7%). We propose a novel secondary structure in a hypervariable region of the 16S rRNA which is useful for alignment of primary sequences and which may be useful for design of nucleic acid probes.

Intracellular growth of Afipia felis, a putative etiologic agent of cat scratch disease

The organism Afipia felis, which is though to be an etiologic agent of cat scratch disease, is a gram-negative rod that is clearly seen in infected tissue but is very difficult to isolate from clinical specimens; there has been only one report to date of the successful isolation and maintenance of the bacterium on artificial medium. We have found that A. felis will attach, invade via phagocytosis, and multiply intracellularly within the phagosomes of primary human monocytes and HeLa cells. Once in the cell, the bacterium appears to change morphologically, becoming longer and more pleomorphic, and loses its ability to grow on an artificial medium. Unique proteins have been identified in both the intra- and extracellular variants of A. felis. Convalescent-phase sera from patients with cat scratch disease react poorly with intracellular and extracellular bacteria, suggesting a poor humoral response. The tissue culture protocol presented has been used to isolate 14 new strains of A. felis and has for the first time permitted study of the pathogenesis of this unique organism.

Characterization of a novel Rochalimaea species, R. henselae sp. nov., isolated from blood of a febrile, human immunodeficiency virus-positive patient

Isolation of a Rochalimaea-like organism from a febrile patient infected with human immunodeficiency virus was confirmed. Analysis of 16S rRNA gene sequences, together with polymerase chain reaction and restriction endonuclease length polymorphism analysis of a portion of the citrate synthase gene, demonstrated that the agent is closely related to members of the genus Rochalimaea and that the isolate is genotypically identical to the presumptive etiologic agent of bacillary angiomatosis. However, the same genotypic analyses readily differentiated the new isolate from isolates of other recognized Rochalimaea species as well as other genera of bacteria previously suggested as putative etiologic agents of bacillary angiomatosis and related syndromes. We propose that the novel species be referred to as Rochalimaea henselae sp. now.

Rochalimaea henselae sp. nov., a cause of septicemia, bacillary angiomatosis, and parenchymal bacillary peliosis

Nine strains of Rochalimaea spp. that were isolated from patients over a period of 4.5 years were characterized for their enzyme activities, cellular fatty acid compositions, and DNA interrelatedness among Rochalimaea spp., Bartonella bacilliformis, and Afipia felis (cat scratch disease bacillus). All except one isolate, which was Rochalimaea quintana, were determined to belong to a newly proposed species, Rochalimaea henselae sp. nov. After recovery from clinical material, colonies required 5 to 15 days of incubation to become apparent. Cells were small, gram-negative, curved bacilli and displayed twitching motility. Enzyme specificities for amino acid and carbohydrate substrates showed that R. henselae could be distinguished from Rochalimaea vinsonii by L-arginyl-L-arginine and L-lysyl-L-alanine peptidases, but not all strains could be distinguished from R. quintana on the basis of peptidases or carbohydrate utilization. R. henselae also closely resembled R. quintana in cellular fatty acid composition, with both consisting mainly of C18:1, C18:0, and C16:0 fatty acids. However, the strains of R. henselae all contained C18:0 in amounts averaging greater than or equal to 22%, in contrast to R. quintana, which contained this cellular fatty acid in amounts averaging 16 and 18%. DNA hybridization confirmed the identification of one clinical isolate as R. quintana and showed a close interrelatedness (92 to 100%) among the other strains. Under optimal conditions for DNA reassociation, R. henselae showed approximately 70% relatedness to R. quintana and approximately 60% relatedness to R. vinsonii. Relatedness with DNA from B. baciliformis was 43%. R. henselae was unrelated to A. felis. R. henselae is the proposed species of a newly recognized member of the family Rickettsiaceae, which is a pathogen that may be encountered in immunocompromised or immunocompetent patients. Prolonged fever with bacteremia or vascular proliferative lesions are clinical manifestations of the agent.

Proposal of Afipia gen. nov., with Afipia felis sp. nov. (formerly the cat scratch disease bacillus), Afipia clevelandensis sp. nov. (formerly the Cleveland Clinic Foundation strain), Afipia broomeae sp. nov., and three unnamed genospecies

On the basis of phenotypic characterization and DNA relatedness determinations, the genus Afipia gen. nov., which contains six species, is described. The type species is Afipia felis sp. nov. (the cat scratch disease bacillus). Afipia clevelandensis sp. nov., Afipia broomeae sp. nov., and three unnamed not associated with cat-borne disease. All but one strain (Afipia genospecies 3) were isolated from human wound and respiratory sources. All Afipia species are gram-negative, oxidase-positive, nonfermentative rods in the alpha-2 subgroup of the class Proteobacteria. They are motile by means of a single flagellum. They grow on buffered charcoal-yeast extract agar and nutrient broth, but rarely on MacConkey agar, at 25 and 30 degrees C. They are urease positive; but they are negative in reactions for hemolysis, indole production, H2S production (triple sugar iron agar), gelatin hydrolysis, esculin hydrolysis, and peptonization of litmus milk. They do not produce acid oxidatively from D-glucose, lactose, maltose, or sucrose. The major cell wall fatty acids are 11-methyloctadec-12-enoic (CBr19:1), cis-octadec-11-enoic (C18:1omega7c), and generally, 9,10-methylenehexadecanote and 11,12-methyleneoctadecanoate; and there are only trace amounts of hydroxy acids. The guanineplus-cytosine content is 61.5 to 69 mol%. A. felis is positive for nitrate reduction and is delayed positive for acid production from D-xylose, but it is catalase negative. A. clevelandensis is negative in all of these tests. A. broomeae is weakly positive for catalase production and acid production from D-xylose, but it is negative for nitrate reduction.