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Biomedical subjects

J E Koehler

Publications and source records attributed to J E Koehler.

At least 37 records · Page 2Linked to original sources
PubMed1996

Experimental transmission of Bartonella henselae by the cat flea.

Bartonella henselae is an emerging bacterial pathogen, causing cat scratch disease and bacillary angiomatosis. Cats bacteremic with B. henselae constitute a large reservoir from which humans become infected. Prevention of human infection depends on elucidation of the natural history and means of feline infection. We studied 47 cattery cats in a private home for 12 months to determine the longitudinal prevalence of B. henselae bacteremia, the prevalence of B. henselae in the fleas infesting these cats, and whether B. henselae is transmitted experimentally to cats via fleas. Vector-mediated transmission of B.henselae isolates was evaluated by removing fleas from the naturally bacteremic, flea-infested cattery cats and transferring these fleas to specific-pathogen-free (SPF) kittens housed in a controlled, arthropod-free University Animal Facility. B. henselae bacteremia was detected in 89% of the 47 naturally infected cattery cats. A total of 132 fleas were removed from cats whose blood was simultaneously cultured during different seasons and were tested individually for the presence of B. henselae DNA by PCR. B. henselae DNA was detected in 34% of 132 fleas, with seasonal variation, but without an association between the presence or the level of bacteremia in the corresponding cat. Cat fleas removed from bacteremic cattery cats transmitted B. henselae to five SPF kittens in two separate experiments; however, control SPF kittens housed with highly bacteremic kittens in the absence of fleas did not become infected. These data demonstrate that the cat flea readily transmits B. henselae to cats. Control of feline infestation with this arthropod vector may provide an important strategy for the prevention of infection of both humans and cats.

Adult↗
PubMed1995

Intra-abdominal mass associated with gastrointestinal hemorrhage: a new manifestation of bacillary angiomatosis.

Bacillary angiomatosis is a recently described vascular proliferative lesion that occurs most commonly in individuals infected with human immunodeficiency virus. Cutaneous lesions are the most frequently described manifestations of bacillary angiomatosis. However, as culture techniques and disease recognition have improved, additional manifestations have been identified in human immunodeficiency virus-infected individuals, including bacillary peliosis hepatis and isolated bacteremia. Two species of the genus Bartonella (formerly Rochalimaea), Bartonella henselae or Bartonella quintana, have been cultured from the cutaneous lesions of bacillary angiomatosis. A new manifestation of Bartonella infection is reported: an intra-abdominal mass presenting with massive gastrointestinal hemorrhage in a patient with human immunodeficiency virus infection. B. quintana was cultured from a percutaneous needle-biopsy specimen obtained from the highly vascularized intra-abdominal mass. The bacillary angiomatosis lesion resolved after 3 months of tetracycline treatment. Recognition of Bartonella infection is extremely important because it is readily treatable with antibiotic therapy.

Adult↗
PubMed1995

Infections associated with Bartonella species in persons infected with human immunodeficiency virus.

Two members of the genus Bartonella, Bartonella quintana (formerly Rochalimaea quintana) and Bartonella henselae (formerly Rochalimaea henselae), have recently been recognized as agents of severe or fatal disease in patients infected with human immunodeficiency virus (HIV). The development of infection with B. henselae in HIV-infected individuals has been associated with traumatic contact with cats (scratches or bites), and domestic cats have been identified as a major reservoir for this organism. Specific information regarding the transmission of B. henselae to humans is not yet available, but common-sense precautions that minimize exposure to cat-associated organisms are appropriate. Preliminary accounts suggest that B. quintana infections are more common than B. henselae infections among HIV-infected individuals in San Francisco. The source of infection with B. quintana and the mechanism of its transmission remain unknown.

Adult↗
PubMed1995

Genomic fingerprinting of Bartonella species by repetitive element PCR for distinguishing species and isolates.

Repetitive-element PCR (rep-PCR) with primers based on repetitive extragenic palindromic (REP) and enterobacterial repetitive intergenic consensus (ERIC) repeated DNA sequences was used for genomic finger-printing of Bartonella species. This technique was applied by using either extracted genomic DNA or preparations of whole bacterial cells directly. PCR fingerprints with either the REP-based primers (REP-PCR) or primers based on the ERIC repeat (ERIC-PCR) revealed species-specific band patterns for the various Bartonella isolates. DNA fingerprints obtained from rep-PCR of extracted genomic DNA or from preparations of whole cells yielded comparable patterns. ERIC-PCR banding patterns were less complex than those obtained by REP-PCR but allowed better discrimination between strains within species. By combining results of REP-PCR and ERIC-PCR, five different fingerprint profiles were identified among 17 isolates of Bartonella henselae, but only one profile was identified among the five isolates of Bartonella quintana. Other Bartonella species yielded distinct rep-PCR fingerprints. rep-PCR is a useful technique for identification of Bartonella organisms to the species level and offers the advantage of ease of performance, with only small quantities of cells needed for the whole-cell procedure. This technique also appears to be useful for subtyping B. henselae isolates.

AIDS-Related Opportunistic Infections↗
PubMed1995

Bartonella henselae prevalence in domestic cats in California: risk factors and association between bacteremia and antibody titers.

The isolation of Bartonella henselae, the agent of cat scratch disease, from the blood of naturally infected domestic cats and the demonstration that cats remain bacteremic for several months suggest that cats play a major role as a reservoir for this bacterium. A convenience sample of 205 cats from northern California was selected between 1992 and 1994 to evaluate the B. henselae antibody and bacteremia prevalences and to determine the risk factors and associations between bacteremia and antibody titers. B. henselae was isolated from the blood of 81 cats (39.5%). Forty-two (52%) of these bacteremic cats were found to be infected with > or = 1,000 CFU/ml of blood. Impounded or former stray cats were 2.86 (95% confidence interval [CI] = 1.94, 4.22) times more likely to be bacteremic than the pet cats. Young cats ( < 1 year old) were more likely than adult cats to be bacteremic (relative risk = 1.64; (95% CI = 1.19, 2.28). Bacteremic cats were more likely than nonbacteremic cats to be infested with fleas (relative risk = 1.64; 95% CI = 1.38, 1.96). No association between B. henselae infection and feline immunodeficiency virus antibody prevalence was observed. Eighty-one percent of the cats (166 of 205) tested positive for B. henselae antibodies, and titers were higher in bacteremic than in nonbacteremic cats. Multiple logistic regression analysis indicated that younger age and seropositivity for B. henselae antibodies were associated with bacteremia. Serological screening for Bartonella antibodies may not be useful for the identification of bacteremic cats (positive predictive value = 46.4%), but the lack of antibodies to B. henselae was highly predictive of the absence of bacteremia (negative predictive value = 89.7%). Seronegative cats may be more appropriate pets for immunocompromised individuals who are at increased risk for developing severe B. henselae disease.

Aging↗
PubMed1994

Rochalimaea henselae infection. A new zoonosis with the domestic cat as reservoir.

OBJECTIVE: To determine the reservoir and vector(s) for Rochalimaea henselae, a causative agent of bacillary angiomatosis (BA) and cat scratch disease, and to estimate the percentage of domestic cats with R henselae bacteremia in the Greater San Francisco Bay Region of Northern California. DESIGN: Hospital-based survey of patients diagnosed with BA who also had significant exposure to at least one pet cat, as well as a convenience sampling of pet or impounded cats for prevalence of Rochalimaea bacteremia. SETTING: Community and university hospitals and clinics; veterinary clinics treating privately owned or impounded cats. PATIENTS: Patients with or without human immunodeficiency virus infection, with biopsy-confirmed BA, who had prolonged exposure to pet cats prior to developing BA. MAIN OUTCOME MEASURES: Cultures and laboratory studies were performed on blood drawn from pet cats associated with patients with BA. The Rochalimaea species infecting pet cats and fleas and causing the BA lesions in human contacts of these cats was identified by culture, polymerase chain reaction-restriction fragment length polymorphism analysis, and DNA sequencing. The presence of R henselae bacteremia in pet cats was documented, and predictor variables for culture positivity were evaluated. RESULTS: Four patients diagnosed with BA who had prolonged contact with seven pet cats were identified. The Rochalimaea species causing BA lesions in these patients was determined to be R henselae. The seven pet cats were found to be bacteremic with R henselae; this bacterium was also detected in fleas taken from an infected cat by both direct culture and polymerase chain reaction. Blood samples were cultured from pet and impounded cats (N = 61) in the Greater San Francisco Bay Region, and R henselae was isolated from 41% (25/61) of these cats. CONCLUSION: We have documented that the domestic cat serves as a major persistent reservoir for R henselae, with prolonged, asymptomatic bacteremia from which humans, especially the immunocompromised, may acquire potentially serious infections. Antibiotic treatment of infected cats and control of flea infestation are potential strategies for decreasing human exposure to R henselae.

Adult↗
PubMed1993

The epidemiology of bacillary angiomatosis and bacillary peliosis.

OBJECTIVE: To determine environmental risk factors for bacillary angiomatosis-bacillary peliosis (BAP), and to confirm infection with Rochalimaea species. DESIGN: Case-control study. SETTING: Community and university hospitals and clinics. PATIENTS: Case patients (N = 48) had biopsy-confirmed BAP. Controls (N = 94) were matched to patients by institution and by human immunodeficiency virus (HIV) serological status. MAIN OUTCOME MEASURES: Clinical information was obtained from medical records. Subjects were queried about environmental exposures. Univariate odds ratios (ORs) with 95% confidence intervals (CIs) were determined. Bivariate analyses were performed on variables associated with disease by univariate analysis. DNA from 22 available case-patient tissues and from 22 control tissues was amplified with the polymerase chain reaction (PCR) using primers designed to detect Rochalimaea species. RESULTS: We identified five HIV-negative, immunocompetent case patients; one HIV-negative, immunodeficient case patient; and 42 HIV-positive case patients. There were no significant differences between case patients and controls by race, sex, age, or risk factors for HIV infection. Owning a cat (OR, 2.8; CI, 1.4 to 5.8) and history of a recent cat lick (OR, 1.95; CI, 1.0 to 3.8), cat scratch (OR, 3.7; CI, 1.7 to 8.0), or cat bite (OR, 3.9; CI, 1.8 to 8.9) were associated with disease in the univariate analysis. In bivariate analyses, only the variables representing traumatic contact with a cat (bite or scratch) remained associated with disease. No other environmental exposure was associated with disease. The PCR amplified a DNA fragment of the size expected for Rochalimaea species in all 22 case-patient tissue specimens. CONCLUSIONS: These data suggest that BAP is a new zoonosis associated with both traumatic exposure to cats and infection with Rochalimaea species or a closely related organism.

Adult↗
PubMed1993

Interaction between the Chlamydia trachomatis histone H1-like protein (Hc1) and DNA.

The gene encoding the Chlamydia trachomatis histone H1-like protein (Hc1) from serovar L2 was cloned into Escherichia coli by use of expression vector pET11d. In this vector, transcription of the gene is under the control of a bacteriophage T7 promoter, and T7 RNA polymerase is inducible in the host. Following induction, the E. coli cells were lysed gently. Gel filtration of the lysate revealed comigration of DNA and Hc1 in the voided volume. Electron microscopy revealed the DNA to be complexed with protein in large aggregates, often in the form of spherical bodies. Purified recombinant Hc1 maintained its DNA-binding capacity and was able at high concentrations to form condensed aggregates with DNA (one molecule of Hc1 per base pair) independently of the form or size of the DNA but with a slight preference for supercoiled DNA. Hc1 alone is thus able to package DNA into condensed spherical bodies.

Base Sequence↗
PubMed1992

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.

AIDS-Related Opportunistic Infections↗
PubMed1992

Overexpression and surface localization of the Chlamydia trachomatis major outer membrane protein in Escherichia coli.

The Chlamydia trachomatis major outer membrane protein (MOMP) is the quantitatively predominant surface protein which has important functional, structural and antigenic properties. We have cloned and overexpressed the MOMP in Escherichia coli. The MOMP is surface exposed in C. trachomatis and capable of eliciting protective antibodies in infected hosts, and therefore has potential as a candidate vaccine to prevent infection with this significant human pathogen. The recombinant MOMP clone, L2rMOMP, contained the entire MOMP gene including the encoded leader sequence. Large quantities of chlamydial MOMP were expressed, some of which was processed and translocated to the E. coli surface. Surface localization of the MOMP was demonstrated by the binding of anti-MOMP monoclonal antibodies to the surface of the induced clone, and was visualized by fluorescence and electron microscopy. The induction of MOMP expression had a rapidly lethal effect on the L2rMOMP E. coli clone. Although no genetic system exists for Chlamydia, development of a stable, inducible E. coli clone which overexpresses the chlamydial MOMP permits a study of the biological properties of the MOMP, including the contribution of the MOMP variable segments to the topographical interactions which determine the antigenic structure responsible for human immune response.

Antibodies, Bacterial↗
PubMed1992

Surveillance for epidemic cholera in the Americas: an assessment.

In January 1991, epidemic cholera appeared in Peru and quickly spread to many other Latin American countries. Because reporting of cholera cases was often delayed in some areas, the scope of the epidemic was unclear. An assessment of the conduct of surveillance for cholera in several countries identified some recurrent problems involving surveillance case definitions, laboratory surveillance, surveillance methods, national coordination, and data management. A key conclusion is that a simple, well-communicated cholera surveillance system in place during an epidemic will facilitate prevention and treatment efforts. We recommend the following measures: a) simplify case definitions for cholera; b) focus on laboratory surveillance of patients with diarrhea primarily in the initial stage of the epidemic; c) use predominantly the "suspect" case definition when the number of "confirmed" cases rises; d) transmit weekly the numbers of cases, hospitalized patients, and deaths to regional and central levels; e) analyze data frequently and distribute a weekly or biweekly summary; and f) report the number of cholera cases promptly to the World Health Organization.

Adult↗