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PubMed1996

Hypertrophic gastropathy in Helicobacter felis-infected wild-type C57BL/6 mice and p53 hemizygous transgenic mice.

BACKGROUND & AIMS: Helicobacter pylori infection causes gastritis and peptic ulcers and is linked epidemiologically to gastric cancer. To analyze host genetic factors and the influence of Helicobacter on cell proliferation, we used an inbred and p53 hemizygous mouse model of Helicobacter felis-induced gastritis. METHODS: H. felis was inoculated by gastric intubation into SPF C57BL/6 wild-type and p53 hemizygous mice that were followed up for 1 year and compared with uninfected controls of the same genotype using histology, proliferating cell nuclear antigen (PCNA) staining, and 5-bromo-2'-deoxyuridine (BrdU) analysis. RESULTS: Infected animalls developed sustained anti-H. felis serum immunoglobulin G antibody responses. Six months after infection, both wild-type and p53 hemizygous mice showed active chronic inflammation and marked mucosal hyperplasia compared with uninfected controls. One year after infection with H. felis, the wild-type and p53 hemizygous mice showed severe adenomatous and cystic hyperplasia of the surface foveolar epithelium. BrdU uptake and PCNA staining were markedly increased in both sets of infected mice compared with controls. Infected p53 hemizygous mice had a higher proliferative index than the infected wild-type mice. CONCLUSIONS: H. felis can induce a hypertrophic gastropathy in the C57BL/6 genotype; loss of one p53 allele, although insufficient to initiate carcinogenesis at 1 year, enhances the proliferative index, which may lead to an increased risk of cancer induction.

Alleles↗
PubMed1993

Cloning, expression and sequencing of Helicobacter felis urease genes.

Urease genes from Helicobacter felis were cloned and expressed in Escherichia coli cells. A genomic bank of Sau3A-digested H. felis chromosomal DNA was created using a cosmid vector. Cosmid clones were screened for urease activity following subculture on a nitrogen-limiting medium. Subcloning of DNA from an urease-positive cosmid clone led to the construction of pILL205 (9.5 kb) which conferred a urease activity of 1.2 +/- 0.5 mumole urea min-1 mg-1 bacterial protein to E. coli HB101 bacteria grown on a nitrogen-limiting medium. Random mutagenesis using a MiniTn3-Km transposable element permitted the identification of three DNA regions on pILL205 which were necessary for the expression of an urease-positive phenotype in E. coli clones. To localize the putative structural genes of H. felis on pILL205, extracts of clones harbouring the mutated copies of the plasmid were analysed by Western blotting with anti-H. felis rabbit serum. One mutant clone did not synthesize the putative UreB subunit of H. felis urease and it was postulated that the transposable element had disrupted the corresponding structural gene. By sequencing the DNA region adjacent to the transposon insertion site two open reading frames, designated ureA and ureB, were identified. The polypeptides encoded by these genes had calculated molecular masses of 26,074 and 61,663 Da, respectively, and shared 73.5% and 88.2% identity with the corresponding gene products of Helicobacter pylori urease.

Amino Acid Sequence↗
PubMed1997

Production and characterization of mouse monoclonal antibodies against Afipia felis.

A series of 10 monoclonal antibodies reacting with Afipia felis antigens were selected from mice immunized with live organisms of the reference strain ATCC 53690. Immunoblotting against SDS-PAGE-separated A felis sonicate allowed the antibodies to be classified into three groups: 1) 168-4, -6, -7 and -10 reacted with a 53 kDa antigen, 2) 168-1, -3 and -9 reacted with both 53 kDa and 60 kDa antigens, and 3) 168-2, -5 and -9 reacted with other antigens. Antibodies of group 1 did not cross-react with other Afipia species or 36 unrelated bacteria, whereas those of groups 2 and 3 reacted with other Afipia species and some unrelated bacteria. Immunoblots of crossed immunoelectrophoretic patterns of A. felis sonicate against rabbit antiserum showed that antibodies of groups 1 and 2 bound to the same precipitin arcs. Antibodies of group 1 reacted with a species-specific epitope on the 53 kDa antigen, while those of group 2 reacted with other epitopes shared by the 53 kDa and 60 kDa antigens. The binding of antibodies of group 1 to A. felis sonicate was inhibited by post-infection rabbit serum, whereas no inhibition was observed for antibodies of group 2. The species-specific epitope of the 53 kDa antigen and the early appearance of antibodies against this epitope after infection suggest that this antigen can be used in a serodiagnostic test for A. felis infection.

Animals↗
PubMed1993

Antibiotic susceptibilities of Afipia felis in axenic medium and in cells.

Afipia felis, one of the putative agents of cat scratch disease (CSD), is a facultative intracellular bacterium. Although CSD is considered not to be susceptible to antibiotic therapy, sporadic case reports indicated that aminoglycosides may be effective. We determined the in vitro antibiotic susceptibilities of three A. felis strains in axenic medium and in a cell model. In axenic medium, A. felis was susceptible to imipenem, aminoglycosides, and rifampin when using either the broth dilution technique or the agar technique. When grown in HeLa cells, A. felis was susceptible to amikacin and tobramycin but was resistant to the other compounds tested. Despite its intracellular location, A. felis can apparently be reached by aminoglycosides. Thus, the in vitro data presented here are in accord with the clinical data obtained in patients suffering CSD.

Anti-Bacterial Agents↗
PubMed1991

Helicobacter felis gastritis in gnotobiotic rats: an animal model of Helicobacter pylori gastritis.

The gastric spirillum Helicobacter felis, originally isolated from the cat stomach, colonizes the stomachs of germfree rats. Studies were designed to examine the pathological and serological responses of germfree rats inoculated orally with H. felis. At 2 weeks postinoculation, the gastric mucosa of germfree rats had lymphocytes and eosinophils scattered in small foci throughout the subglandular region of the antrum. Small numbers of lymphocytes were present in the subglandular portion of the antral mucosa that focally extended through the lamina propria towards the luminal surface. Eight weeks postinoculation, the inflammation was confined to the antrum. It was characterized by increased numbers of lymphocytes and eosinophils in the subglandular areas, with focal aggregates of lymphocytes in the submucosa. Some lymphoid aggregates extended from the submucosa through the muscularis mucosa and lamina propria to the luminal surface. H. felis was demonstrated with the Warthin-Starry stain, bacterial culture, and urease assay, particularly in the antrum. H. felis also produced a significant immunoglobulin G antibody titer at 2, 4, and 8 weeks postinoculation as well as a transitory immunoglobulin M response at 2 to 4 weeks postinoculation. Contact control rats were not infected, inferring that fecal-oral spread of H. felis did not occur.

Animals↗
PubMed1997

Western immunoblot analysis of Haemobartonella muris and comparison of 16S rRNA gene sequences of H. muris, H. felis, and Eperythrozoon suis.

Infectious agents were isolated from the spleens of three wild mice (Apodemus argenteus) by intraperitoneal inoculation of the spleen homogenate into laboratory mice. The laboratory mice developed clinical signs and splenomegaly, and three isolates were maintained by passage in mice. Tetracyclines were effective in preventing infection of mice with these agents, but streptomycin and penicillin were ineffective. The agents did not grow in bacterial growth media or chicken embryos. In smears of blood from infected mice stained by the Giemsa or the indirect immunofluorescence method, numerous organisms were found on the surfaces of erythrocytes. Electron microscopy revealed cell wall-less pleomorphic cocci of 350 to 700 nm in diameter. On the basis of these results, the isolates were identified as Haemobartonella muris. There was no antigenic cross-reactivity with Rickettsia or Ehrlichia spp. or other related organisms. Western immunoblot analysis of three strains of H. muris with mouse antisera to H. muris revealed identical major antigens of 118, 65, 53, 45, and 40 kDa. By heteroduplex analysis of the three PCR-amplified segments of the 16S rRNA genes, the three strains of H. muris were found to be identical. The 16S rRNA genes of one of the H. muris strains, four strains of H. felis, and two strains of Eperythrozoon suis were sequenced and compared. The sequences of two strains of H. felis from cats in California were identical, as were the sequences of a strain from a cat in Ohio and a strain from a cat in Florida, but the similarity of sequences between the California and the Ohio-Florida strains was only 85%. The sequence of an H. muris strain was unique and was more closely related to that of the Ohio-Florida strain of H. felis (89%) than to that of the California strain of H. felis (84%). The sequence of E. suis from a pig in Illinois was identical to that from another pig from Taiwan. The similarity of the 16S rRNA gene sequence of E. suis with those of three Haemobartonella strains was 84 to 92%, with that of E. suis being most similar to that of the H. felis strain from California. In the phylogenetic analysis based on 16S rRNA gene sequences, the Haemobartonella spp. and E. suis formed a distinct clade more closely related to Mycoplasma spp. (79 to 83% similarity) than to Anaplasma marginale (72 to 75% similarity). Our results suggest that the Haemobartonella spp. and E. suis may be reclassified in the same genus in the family Mycoplasmataceae.

Anaplasmataceae↗
PubMed2006

Pharmacokinetics of enrofloxacin and its efficacy in comparison with doxycycline in the treatment of Chlamydophila felis infection in cats with conjunctivitis.

The concentrations of enrofloxacin were measured in the tears, saliva and serum of 14 cats with signs of upper respiratory tract infection and eight with no signs, after daily doses of 5 mg/kg. Enrofloxacin concentrations above the minimum inhibitory concentration of Chlamydophila felis were found in the saliva and tears of the cats with and without signs of upper respiratory tract infection. In a prospective randomised clinical trial, the efficacy of enrofloxacin against C. felis infection in cats with conjunctivitis was compared with the efficacy of doxycycline. Twenty-five cats were randomly assigned to treatment with either enrofloxacin or doxycycline for 14 days; 15 of the cats tested positive for C. felis by an immunofluorescent antibody test on conjunctival swabs. The two treatment groups showed equal improvements in the clinical signs of conjunctivitis and C. felis infection status; in each group three cats were still C. felis antigen-positive after the 14-day course of treatment, indicating a persistent infection. No side effects were observed in the cats treated with enrofloxacin.

Animals↗
PubMed1993

Protective immune response of Isospora felis-infected mice against Babesia microti infection.

Protective response against Babesia microti was studied in Isospora felis-infected mice. Isospora felis-infected mice which were exposed to B. microti on the 28th day post-infection showed absolute resistance against Babesia microti. Interestingly, these mice showed no anti-B. microti antibodies. Mice that received spleen cells from I. felis-infected donors that were subsequently exposed to B. microti showed lower peak parasitemia (10.3% +/- 2.6) compared to those mice that received normal spleen cells (60.9% +/- 15.0), and no spleen cells at all (47.3% +/- 8.5). Treatment of I. felis-infected mice with monoclonal antibodies against L3T4+ cells resulted to a depression of their resistance to B. microti, as clearly manifested by high levels of parasitemia. Findings of the present study demonstrate the role of cell mediated immunity, specifically by L3T4+ T-cells induced by I. felis infection, in providing mice protection against B. microti.

Animals↗
PubMed2003

Molecular detection and characterization of Haemobartonella felis in domestic cats in Japan employing sequence-specific polymerase chain reaction (SS-PCR).

A novel PCR assay was developed in order to examine the prevalence of Haemobartonella felis (H. felis) in Japanese domestic cats and which was able to differentiate of the Ohio strain and the California strain of H. felis. Blood samples from a total of 21 cats suspected of having haemobartonellosis were examined employing a novel PCR assay and demonstrated positive results in 18 cats which was confirmed by cytological examination of blood smears. Four out of 18 positive cats (22%) were infected with the California strain, whilst the other 12 cats (67%) were infected with the Ohio strain and two animals (11%) were infected with both strains. As most of the cats with moderate to severe anemia were infected with the Ohio strain, it is suggested that the most prevalent strain of H. felis in Japanese domestic cats might be the Ohio strain. In the present study, it was thought that molecular detection and characterization of H. felis may provide valuable information regarding the severity and prognosis of this illness.

Animals↗
PubMed1999

Helicobacter felis infection in dogs: effect on gastric structure and function.

The relationship of Helicobacter felis, an organism that is observed in the stomachs of dogs, to gastric disease in dogs is unclear. The objective of this study was to determine if Helicobacter felis infection alters gastric morphology and gastric secretory function in dogs. Five specific-pathogen-free (SPF), Helicobacter-free Beagle dogs were examined before and for 26 weeks after inoculation with H. felis (ATCC 49179). Three SPF uninfected dogs served as controls. All five dogs became colonized by H. felis as determined by urease activity, histopathology, polymerase chain reaction, and transmission electron microscopic examination of serial gastric biopsies. The degree of colonization ranged from < 1 organism/400 x field to > 10 organisms/400 x field. The fundus, body, and cardia were most heavily colonized. Evaluation of gastric biopsies showed mild gastric inflammation and lymphoid follicles in both infected and uninfected dogs. There was no correlation between the number of organisms observed and the degree of gastric inflammation or number of lymphoid follicles. The gastric secretory axis, assessed by fasting and meal-stimulated plasma gastrin, mucosal gastrin and somatostatin immunoreactivity, fasting gastric pH, and pentagastrin-stimulated gastric acid secretion, was similar in both infected and uninfected dogs. Fasting gastric pH was not a reliable indicator of gastric secretory function. These findings suggest that H. felis may not be a gastric pathogen in dogs. However, the density of colonization and limited duration of infection should be considered when interpreting these findings.

Animals↗
PubMed2005

Polymerase chain reaction detection of Cytauxzoon felis from field-collected ticks and sequence analysis of the small subunit and internal transcribed spacer 1 region of the ribosomal RNA gene.

Cytauxzoon felis produces a disease in domestic cats in the Midwest (U.S.A.), which often leads to a fatal outcome. Although the clinical disease process is well described, there are still many unanswered questions about this organism. For example, it is unknown whether species of ticks other than Dermacentor variabilis can serve as vectors for transmission. With recent reports of surviving cats from limited geographic areas, another relevant question is the potential for genetically less virulent organism strains. This study evaluated 352 individual or pooled tick samples (1,362 total ticks) for the presence of C. felis small subunit ribosomal RNA and internal transcribed spacer 1 (ITS-1) region genes using a polymerase chain reaction (PCR). These ticks were collected from dogs and cats in several Missouri counties, including 10 from cats diagnosed with cytauxzoonosis. Only 3 positive C. felis samples were identified in Amblyomma americanum nymphs, and there was very limited genetic variation noted in both genes. The small number of positive samples did not allow the study to determine which PCR analysis was more sensitive. This is the first known report of ITS-1 gene identification and sequencing for C. felis. It is also the first published investigation of genetic variation in C. felis.

Animals↗
PubMed2001

Inoculation of two genotypes of Hemobartonella felis (California and Ohio variants) to induce infection in cats and the response to treatment with azithromycin.

OBJECTIVES: To describe clinical and laboratory findings associated with cats experimentally infected by inoculation with the 2 recognized genotypes of Hemobartonella felis (small variant, Hfsm; large variant, Hflg) and to determine the response of cats to treatment with azithromycin. ANIMALS: 18 young adult domestic shorthair cats of both sexes. PROCEDURES: Cats were inoculated with H felis and monitored weekly, using CBC counts and a polymerase chain reaction (PCR) designed to detect both genetic variants of H felis. Beginning 26 days after inoculation, 11 cats were administered azithromycin (15 mg/kg of body weight, PO, q 12 h, for 7 days). RESULTS: Inoculation resulted in coinfection with Hflg and Hfsm, and both variants were detected by PCR. Clinical abnormalities and anemia were most severe in Hflg- and dual-infected cats. Results of PCR and CBC were positive for H felis in 112/112 (100%) and 42/112 (37.5%), respectively, samples collected after inoculation. Administration of azithromycin had little effect on clinical variables, including anemia. All cats, regardless of treatment with azithromycin, had positive results for the PCR at the end of the study period. CONCLUSIONS AND CLINICAL RELEVANCE: In these cats, Hflg was more pathogenic than Hfsm, and coinfection with both variants was detected. Results of the PCR were superior to results of CBC for detecting infection with H felis. Azithromycin administered at the dose and duration reported here was not efficacious for the treatment of cats with hemobartonellosis.

Anaplasmataceae↗
PubMed2006

Attempted transmission of Candidatus Mycoplasma haemominutum and Mycoplasma haemofelis by feeding cats infected Ctenocephalides felis.

OBJECTIVE: To determine whether Mycoplasma haemofelis (Mhf) and Candidatus Mycoplasma haemominutum (Mhm) can be transmitted by ingestion of Mycoplasma-infected Ctenocephalides felis and by-products (feces, larvae, and eggs). ANIMALS: 10 cats. PROCEDURE: 3 cats were carriers of Mhf, and 1 was a carrier of Mhm. Six cats had negative results of PCR assay for Mhf and Mhm DNA. A chamber containing 100 C felis was bandaged to 2 Mhf carrier cats. Five days later, fleas and by-products were analyzed for Mycoplasma spp DNA. The remaining fleas and a sample of by-products were fed to 2 Mycoplasma-naïve cats. A chamber containing 200 C felis was bandaged to the Mhm carrier cat. Five days later, fleas and by-products were analyzed for Mycoplasma spp DNA. The remaining fleas and a sample of by-products were fed to 2 Mycoplasma-naïve cats. A chamber containing 200 C felis was bandaged to an Mhf carrier cat and Mhm-carrier cat. Three days later, fleas and by-products were analyzed for Mycoplasma spp DNA. The remaining fleas and a random sample of by products were fed to 4 Mycoplasma-naïve cats. All cats were monitored for infection for >or=7 weeks. RESULTS: Uptake of Mhf and Mhm DNA into fleas and by-products was detected. None of the naïve cats became infected. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that ingestion of Mycoplasma-infected C felis or by-products is not an important means of transmission for Mhf or Mhm.

Animals↗
PubMed2002

Use of enrofloxacin for treatment of large-form Haemobartonella felis in experimentally infected cats.

OBJECTIVE: To compare treatment with enrofloxacin and doxycycline with no treatment in cats experimentally infected with Haemobartonella felis. DESIGN: Prospective case-control study. ANIMALS: 16 cats. PROCEDURE: Cats were inoculated with large-form H. felis from a chronically infected donor. Cats were assigned to 1 of 4 treatment groups: doxycycline (5 mg/kg [2.3 mg/lb], p.o., q 12 h), low-dose enrofloxacin (5 mg/kg, p.o., q 24 h), high-dose enrofloxacin (10 mg/kg [4.5 mg/lb], p.o., q 24 h), and an untreated control group. Clinical signs, Hct, blood smears, and a polymerase chain reaction (PCR) assay were used to monitor progression of the infection. RESULTS: All cats were confirmed to be infected with H. felis via blood smear evaluations and PCR assay results. Treatment had no effect on Hct during the intratreatment period, but Hct values were significantly greater in the low-dose enrofloxacin group, compared with the control group, during the posttreatment period. During the intratreatment period, H. felis organism counts per 1,000 RBC in the doxycycline treatment and the high-dose enrofloxacin treatment groups decreased at a significantly faster rate than those in the control group. In the posttreatment period, organism counts in the doxycycline treatment group and the low- and high-dose enrofloxacin groups decreased at significantly faster rates than counts in the control group. There was no significant effect of treatment on the number of positive PCR assay results. Two cats treated with enrofloxacin and 1 cat treated with doxycycline completely cleared the H. fe is organism despite presumed immunosuppression caused by glucocorticoids. CONCLUSIONS AND CLINICAL RELEVANCE: Results support the hypothesis that enrofloxacin has anti-H. felis effects.

Anaplasmataceae↗
PubMed1996

The Helicobacter felis mouse model in assessing anti-Helicobacter therapies and gastric mucosal prostaglandin E2 levels.

BACKGROUND: The aims of the present study were to assess the usefulness of the Helicobacter felis mouse model in the evaluation of antimicrobial therapies and the effect of Helicobacter infection on gastric mucosal prostaglandin E2 release. METHODS: Barrier-maintained BALB/c mice were infected with H. felis and treated with different antibacterial therapies. H. felis status was determined by bacterial culture, urease test, and bacterial and histologic stainings. Release of prostaglandin E2 from the gastric mucosa was measured by radioimmunoassay. RESULTS: All triple-treated mice were cleared of bacteria both 24 h and 1 month after treatment. However, tinidazole alone also resulted in 100% eradication. Monotherapies with erythromycin acistrate, tetracycline, colloidal bismuth subcitrate, and nitecapone failed to eradicate the bacteria. The release of gastric prostaglandin E2 was doubled in the infected mice (554 +/- 39, mean +/- SE) compared with the noninfected mice (270 +/- 35) (p < 0.01). CONCLUSIONS: The H. felis mouse model proved satisfactory for assessing both anti-Helicobacter therapies and the prostaglandin E2 release. The reliability of this method was improved when several methods to assess the H. felis status were used in parallel.

Amoxicillin↗
PubMed2002

Geographic association of Rickettsia felis-infected opossums with human murine typhus, Texas.

Application of molecular diagnostic technology in the past 10 years has resulted in the discovery of several new species of pathogenic rickettsiae, including Rickettsia felis. As more sequence information for rickettsial genes has become available, the data have been used to reclassify rickettsial species and to develop new diagnostic tools for analysis of mixed rickettsial pathogens. R. felis has been associated with opossums and their fleas in Texas and California. Because R. felis can cause human illness, we investigated the distribution dynamics in the murine typhus-endemic areas of these two states. The geographic distribution of R. felis-infected opossum populations in two well-established endemic foci overlaps with that of the reported human cases of murine typhus. Descriptive epidemiologic analysis of 1998 human cases in Corpus Christi, Texas, identified disease patterns consistent with studies done in the 1980s. A close geographic association of seropositive opossums (22% R. felis; 8% R. typhi) with human murine typhus cases was also observed.

Adolescent↗
PubMed1991

Iatrogenic transmission of Cytauxzoon felis from a Florida panther (Felix concolor coryi) to a domestic cat.

A laboratory cat died 12 days after intraperitoneal inoculation of a 1 ml suspension containing 1.5 x 10(6) blood mononuclear cells from a Florida panther (Felis concolor coryi). Gross, histologic and ultrastructural investigations revealed the cause of death to be infection by Cytauxzoon felis, a protozoal parasite known to cause a rapidly fatal disease (cytauxzoonosis) in domestic cats. The bobcat (Felis rufus) has been identified as a natural host for C. felis. This report implicates the Florida panther as another possible host for C. felis.

Animals↗
PubMed2006

Sarcocystosis of Sarcocystis felis in cats.

The features of S. felis sarcocystosis in muscles of the domestic cats (Felis domesticus) were studied. A complete clinical history, post mortem, and histo-pathologic examinations were done for each cat. Multiple protozoan elliptical cysts were in the skeletal muscles, heart, and diaphragm muscles of 3/17 (17.6%) adult cats. Ultrastructural characteristics of the bradyzoites and cyst wall were consistent with those described for S. felis in bobcat and domestic cat. Clinico-pathological study in 3 cats showed hypertrophy cardiomyopathy and lymphosarcoma associated with S. felis. Tissue samples showed a spectrum of pathological changes such as multi-focal subacute myocarditis and multi-focal subarachnoid lymphocytic infiltration. DNA extracted from muscles diaphragm with cysts was tested by PCR and sequence analyses of ssurRNA gene. The phylogenetic reconstructions using neighbor-joining method showed that S. felis is closely related to S. neurona. The results were illustrated and photographed and peer discussed.

Animals↗