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Biomedical subjects

D F Welch

Publications and source records attributed to D F Welch.

At least 19 recordsLinked to original sources
PubMed1999

Immune response of neonatal specific pathogen-free cats to experimental infection with Bartonella henselae.

The purpose of this study was to determine whether neonatal cats develop and maintain a persistent bacteremia for longer than do adult cats with a normal mature immune system, and whether neonatal cats are susceptible to infection with Bartonella henselae by oral inoculation. Neonatal specific pathogen-free (SPF) cats were inoculated with B. henselae intradermally (n = 4) or orally (n = 5) or with 0.9% NaCl (n = 2). Blood was collected periodically through 16 weeks post-inoculation (PI) for serology, bacteriology and complete blood count. Cats inoculated orally or intradermally at 3-5 days of age were bacteremic through 12-16 weeks PI, similar to what is documented for adult cats inoculated intradermally or intravenously. One cat inoculated at age 2 weeks was bacteremic through 10 weeks PI; the other was not bacteremic. Intradermally inoculated neonatal cats produced serum IgG antibodies to B. henselae but orally inoculated neonatal cats did not. Infected cats with and without serum IgG antibodies to B. henselae became blood-culture negative simultaneously, suggesting that IgG is not required to clear bacteremia.

Animals↗
PubMed1999

Isolation of a new subspecies, Bartonella vinsonii subsp. arupensis, from a cattle rancher: identity with isolates found in conjunction with Borrelia burgdorferi and Babesia microti among naturally infected mice.

Bacteremia with fever due to a novel subspecies of Bartonella vinsonii was found in a cattle rancher. The subspecies shared major characteristics of the genus Bartonella in terms of most biochemical features and cellular fatty acid profile, but it was distinguishable from other subspecies of B. vinsonii by good growth on heart infusion agar supplemented with X factor and by its pattern of enzymatic hydrolysis of peptide substrates. DNA relatedness studies verified that the isolate belonged to the genus Bartonella and that it was genotypically related to B. vinsonii. The highest level of relatedness was observed with recently characterized strains from naturally infected mice that were coinfected with Borrelia burgdorferi and Babesia microti. We propose the name Bartonella vinsonii subsp. arupensis subsp. nov. as the new subspecies to accommodate these human and murine isolates.

Animals↗
PubMed1998

Evidence of reproductive failure and lack of perinatal transmission of Bartonella henselae in experimentally infected cats.

Five female specific pathogen-free (SPF) cats inoculated intradermally with B. henselae and bacteremic for 4 weeks, and one cat inoculated with 0.9% NaCl, were bred with uninfected SPF male cats. The uninfected female became pregnant with one breeding, while three infected cats became pregnant 1-12 weeks later, after repeated breedings. Two infected females either did not become pregnant or maintain pregnancies despite repeated breedings. Infected cats produced anti-B. henselae IgM and IgG antibodies. Fetuses and kittens of infected cats were not infected and did not produce anti-B. henselae antibodies. Male cats bred with infected females did not become infected or seroconvert. Maternal anti-B. henselae IgG antibodies detected in sera of kittens 2 weeks post-partum were no longer detectable 10 weeks post-partum. These findings suggest that B. henselae causes reproductive failure in female cats, but is not transmitted transplacentally, in colostrum or milk, or venereally. Infected cats immunosuppressed with methylprednisolone acetate after their kittens were weaned had no detectable bacteria in tissues, suggesting that they were no longer infected.

Animals↗
PubMed1998

Cat scratch disease: the rare role of Afipia felis.

Since its isolation in 1988, Afipia felis has been associated with cat scratch disease (CSD) in only one report and its role in CSD has been questioned. We have cultured A. felis from a lymph node of a patient with CSD. 16S rRNA gene sequencing, DNA relatedness studies, fatty acid analysis, and PCR of the A. felis ferredoxin gene showed that the isolate is identical to the previously reported A. felis isolate. To determine the role of A. felis in CSD, PCR of the 16S rRNA gene followed by hybridizations with specific probes were performed with lymph node specimens from CSD patients. All 32 specimens tested positive for Bartonella henselae and negative for A. felis. We conclude that A. felis is a rare cause of CSD. Diagnostic tests not conducive to the identification of A. felis might cause the diagnosis of CSD due to A. felis to be missed.

Adult↗
PubMed1997

Experimental infection of young specific pathogen-free cats with Bartonella henselae.

Eighteen 12-week-old specific pathogen-free cats, blood culture- and serum antibody-negative for Bartonella henselae, were randomly allocated to groups and were intravenously inoculated with 10(10) (group 1), 10(8) (group 2), or 10(6) (group 3) B. henselae or with saline (group 4) or were not inoculated (group 5). Cats were humanely killed at 2, 4, 8, 16, and 32 weeks after inoculation. All B. henselae-inoculated cats were bacteremic by 2 weeks after infection. Bacteremia persisted until 32 weeks after infection in 1 cat. Cats in groups 1 and 2 had fever (>39.7 degrees C) and partial anorexia by 2 weeks after infection that lasted 2-7 days. All infected cats had Bartonella-specific IgM and IgG serum antibodies and lymphocyte blastogenic responses. Histopathologic lesions were observed in multiple organs of infected cats through 8 weeks after infection. Cats were readily infected with B. henselae by intravenous inoculation, developed histopathologic lesions that apparently resolved, and developed B and T lymphocyte responses to infection.

Animals↗
PubMed1997

Nosocomial acquisition of Burkholderia gladioli in patients with cystic fibrosis.

Burkholderia gladioli has been reported as colonizing the airways of patients with cystic fibrosis (CF) but has not previously been associated with adverse outcome. We describe six patients with CF in whom the same strain of B. gladioli, on the basis of ribotyping and biochemical characteristics, was grown in their sputum. Acquisition of this organism was followed by a fatal outcome in all six patients; one had a rapid decline in respiratory status and another developed fulminant B. gladioli bacteremia. Evidence suggests that patient-to-patient transmission of the organism occurred, and supports nosocomial infection in the ward and/or outpatient clinic despite general and stringent infection-control measures. This is the first report of adverse clinical outcome following sputum colonization with B. gladioli, and the first to demonstrate person-to-person transmission.

Bacteremia↗
PubMed1996

Protozoal colonization of the intestinal tract in institutionalized Romanian children.

To determine the prevalence of intestinal parasitic infections in 92 Romanian children institutionalized at Colentina Hospital (Bucharest, Romania) and at the Dystrophic Center (Vidra, Romania), medical charts were reviewed and complete physical examinations were performed. The nutritional status of each child was evaluated, and their sera were tested for the presence of antibodies to human immunodeficiency virus (HIV) and Cryptosporidium. Fecal samples were collected in 10% formalin and examined by an immunofluorescent assay and by trichrome staining for intestinal parasites. At least one protozoan was identified in 77% of the fecal specimens examined. Giardia lamblia (72% of cases), Cryptosporidium parvum (12%), and Entamoeba coli (4%) were the only parasites identified. Stepwise logistic regression revealed that the only factors predictive of giardia colonization were normal nutritional status (P < .01) and HIV seropositivity (P < .02), while cryptosporidium colonization was only associated with where the children lived (P < .01). Seventy-three percent of the children had IgA and/or IgG antibodies to Cryptosporidium in their sera. The presence of these antibodies was strongly associated with the severity of symptoms present in the HIV-infected children (P < .01). Protozoal colonization of the intestinal tract is common in institutionalized Romanian children and may play a role in causing morbidity and mortality in this high-risk group of children.

AIDS-Related Opportunistic Infections↗
PubMed1995

Bartonella (Rochalimaea) quintana bacteremia in inner-city patients with chronic alcoholism.

BACKGROUND: Bartonella (Rochalimaea) quintana is a fastidious gram-negative bacterium known to cause trench fever, cutaneous bacillary angiomatosis, and endocarditis. Between January and June 1993 in Seattle, we isolated B. quintana from 34 blood cultures obtained from 10 patients not known to be infected with the human immunodeficiency virus (HIV). METHODS: After identifying the isolates as B. quintana by direct immunofluorescence and DNA-hybridization studies, we determined strain hybridization with studies of restriction-fragment-length polymorphisms (RFLPs) of the intergenic spacer (noncoding) region of ribosomal DNA amplified by the polymerase chain reaction (PCR). To characterize the epidemiologic and clinical features of bartonella infections in these patients, we performed a retrospective case-control study using as controls 20 patients with blood cultures obtained at approximately the same time as those obtained from the index patients. RESULTS: B. quintana isolates from the 10 patients were indistinguishable by PCR-RFLP typing. All 10 patients had chronic alcoholism, and 8 were homeless (P = 0.001 for both comparisons with controls). The six patients who underwent HIV testing were seronegative. At the time of their initial presentation, seven patients had temperatures of at least 38.5 degrees C. Six patients had three or more blood cultures that were positive for B. quintana, and in four of these patients B. quintana was isolated from blood cultures obtained 10 or more days apart. Subacute endocarditis developed in two patients and required surgical removal of the infected aortic valve in one of them. Nine patients recovered; one died of sepsis from Streptococcus pneumoniae infection. CONCLUSIONS: B. quintana is a cause of fever, bacteremia, and endocarditis in HIV-seronegative, homeless, inner-city patients with chronic alcoholism.

Adult↗
PubMed1995

Evaluation of the automated Bact-Alert system for pediatric blood culturing.

The Organon Teknika BacT/Alert (Organon Teknika, Durham, NC), using the Pedi-BacT 20 mL aerobic bottle (BPBCS) was compared to the Wampole Isolator (WI) 1.5 Microbial tube (Wampole Laboratories, Cranbury, NJ), for detection and recovery of pediatric pathogens. The BPBCS continuously monitors culture bottles for changes in CO2 concentrations, while WI cultures are examined twice daily for appearance of colonial growth on agar media. Of 5,175 paired blood cultures, 383 pathogens were recovered from 606 positive cultures. There were 272 pathogens recovered by both systems, 64 from BPBCS only, and 47 from WI only. Overall recovery rates were 88% for BPBCS and 83% for WI. There was no significant difference between the two systems in detection or times to positivity of staphylococci, Enterobacteriaceae, or pseudomonads. Trends toward better recovery of streptococci (20 vs. 10) and fastidious microaerophiles (3 vs. 0) were found with BPBCS, whereas more slowly growing pathogens (Rochalimaea henselae [1], Mycobacterium avium-intracellulare [1]) were recovered by WI only, but because of their lower frequency did not achieve statistical significance. Detection of Haemophilus influenzae (14.9 hours in WI vs. 45.4 hours in BPBCS) was faster with WI. False positive plus contaminant cultures were detected in 5.9% BPBCS versus 1.5% WI. BPBCS offers detection of bacteremia at a rate comparable to WI with advantages of automation.

Autoanalysis↗
PubMed1994

Morphologically variable bacilli of cat scratch disease are identified by immunocytochemical labeling with antibodies to Rochalimaea henselae.

The identification of the causative organisms of cat scratch disease (CSD) has been elusive. The demonstration of Warthin-Starry stain-positive pleomorphic bacilli in lymph nodes of patients with CSD and recent serologic and epidemiologic data suggest an etiologic role of Rochalimaea henselae in CSD. The authors studied lymph node biopsy specimens of 46 patients with illnesses clinically consistent with CSD and found pleomorphic bacilli in 15 (33%). The organisms were labeled by polyclonal rabbit antibodies induced by outer surface proteins of R henselae. This finding further supports the possibility of an important role of R henselae in the pathogenesis of CSD.

Adolescent↗
PubMed1994

Detection of Bartonella (Rochalimaea) quintana by routine acridine orange staining of broth blood cultures.

Bartonella quintana was isolated from 34 BACTEC nonradiometric aerobic resin blood cultures for 10 adults. Nine patients were initially diagnosed by routine acridine orange staining of routine cultures that had been incubated for 8 days. All subcultures grew on chocolate agar within 3 to 12 days (median, 6 days). The PLUS 26 high-volume aerobic resin medium, combined with acridine orange stain and subculture, is an effective system for detection and isolation of B. quintana from blood.

Acridine Orange↗
PubMed1993

Invasive pneumococcal disease in central Oklahoma: emergence of high-level penicillin resistance and multiple antibiotic resistance. Pneumococcus Study Group.

Relatively penicillin-resistant pneumococci have caused 10% of invasive pneumococcal disease in central Oklahoma during the last decade, but almost no high-level penicillin or other antibiotic resistance has been described. This study evaluated antibiotic susceptibility and serotype distribution in invasive pneumococcal disease in the Oklahoma City metropolitan area (1990 population 848,000). A total of 144 cases of invasive infection was collected in 1 year (17 with meningitis, 120 with other bacteremic infections, and 7 with other invasive infections), for a rate of 16.9/100,000 (95% confidence interval [CI], 14.0-19.5). For the population aged > or = 60, invasive pneumococcal disease rates were higher among nursing home residents (352/100,000) than among nonresidents (25.6/100,000; relative risk, 13.7; 95% CI, 7.7-24.7). Antibiotic-resistant organisms caused 19.4% of the cases: relative penicillin resistance, 7.6%; high-level penicillin resistance, 1.4% (2 cases), and 11% resistance to erythromycin, trimethoprim-sulfamethoxazole, or both, with 5% sharing both resistances plus a MIC of penicillin of 0.06 microgram/mL.

Adolescent↗
PubMed1993

Septicemia and meningitis caused by Helicobacter cinaedi in a neonate.

Helicobacter cinaedi has been most frequently isolated from rectal swabs of homosexual men with proctocolitis. The microorganism is a normal intestinal inhabitant of hamsters. We report a case of septicemia and meningitis by H. cinaedi in a neonate whose mother cared for pet hamsters during the first two trimesters of her pregnancy. The isolate was detected after 3 days of incubation in a Bact/Alert pediatric blood culture vial and an enrichment broth culture of the cerebrospinal fluid. H. cinaedi should be added to the list of unusual fastidious organisms that cause sepsis and meningitis in the newborn.

Animals↗
PubMed1993

Endocarditis caused by Rochalimaea quintana in a patient infected with human immunodeficiency virus.

Rochalimaea quintana and Rochalimaea henselae are closely related, fastidious, gram-negative rickettsiae. Thus far, the spectrum of human Rochalimaea sp. infections has not included endocarditis. We describe a 50-year-old human immunodeficiency virus-positive man who developed endocarditis caused by R. quintana. DNA relatedness studies, which compared our patient's blood culture isolate with known Rochalimaea species, identified the organism as R. quintana. Our report expands the spectrum of Rochalimaea sp. infections and identifies a new infectious cause of endocarditis.

DNA, Bacterial↗
PubMed1993

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.

Bacterial Typing Techniques↗
PubMed1993

Timely culture for mycobacteria which utilizes a microcolony method.

For the isolation of mycobacteria from clinical specimens, we evaluated a method that used a thinly poured Middlebrook 7H11 agar plate (10 by 90 mm) that was examined microscopically. Inoculated plates were sealed, incubated, and examined at regular intervals for the appearance of microcolonies. Plates were examined microscopically, while still sealed, by focusing on the agar surface through the bottom of the plate and the agar. Plates were scanned at low power (x40 total magnification), and colony morphology was confirmed at intermediate power (x100 to x180 magnification). This method was compared with a traditional method that used macroscopic examination of standard mycobacterial media. By using all specimens submitted for mycobacterial culture over the duration of the study, the method was evaluated until 270 isolates of mycobacteria (Mycobacterium tuberculosis, n = 103; M. avium-M. intracellulare, n = 115; miscellaneous, n = 52) were detected. While the conventional method required an average of 23 days to the time of first detection of mycobacteria, the experimental method required an average of only 11 days. When limited to acid-fast stain-positive specimens that were culture positive for M. tuberculosis, the average interval to positivity was 7 days for the microcolony method compared with 17 days for the conventional method. With the experimental method, the microscopic colonial morphology allowed for the presumptive identification of M. tuberculosis colonies, which were distinguished by cording, and M. avium-M. intracellulare colonies, which were smooth and entire. Presumptive identification was complete for 83.5% of the M. tuberculosis isolates within 10 days and for 85% of the M. avium-M. intracellulare isolates within 11 days after inoculation. If the microcolony method was combined with a conventional tube medium, the composite would optimize for speed of recovery while providing the full sensitivity of the conventional method. In addition to reducing the interval to positivity, the microcolony method allows for the easy detection of mixed mycobacterial infections and yields a presumptive identification that facilitates the selection of a confirmatory gene probe test.

Bacteriological Techniques↗