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Biomedical subjects

D J Brenner

Publications and source records attributed to D J Brenner.

At least 199 records · Page 11Linked to original sources
PubMed1990

Neisseria elongata subsp. nitroreducens subsp. nov., formerly CDC group M-6, a gram-negative bacterium associated with endocarditis.

CDC group M-6 is the vernacular name given to a gram-negative, oxidase-positive, aerobic, nonmotile, rod-shaped bacterium. This organism is biochemically similar to Kingella denitrificans and displays a cellular fatty acid profile consistent with CDC groups M-5 and EF-4 and with Neisseria elongata. Of the 95 M-6 strains referred to the Centers for Disease Control (CDC) for identification, 32 (64%) of the first 50 were from the throat or sputum and only 3 (6%) were from blood; only 5 (11%) of the next 45 isolates were from the upper respiratory tract and 23 (51%) were from blood, with many of these (15 or 65%) being associated with endocarditis. The major characteristics of CDC group M-6 include reduction of nitrate and nitrite with no gas formation; positive reaction for oxidase; negative reactions for catalase, urease, indole, and motility; and no acid production from carbohydrates. Guanine-plus-cytosine content determined spectrophotometrically by thermal denaturation was 55 to 58 mol % for six M-6 strains tested: 56 mol % for the N. elongata subsp. elongata type strain and for the N. elongata subsp. glycolytica type strain. By the hydroxyapatite method, DNAs from 24 M-6 strains showed an average of 78% relatedness to M-6 reference strain B1019 in reactions at 60 degrees C and 73% relatedness in reactions at 75 degrees C. M-6 strain B1019 was 79% related to the N. elongata type strain at 60 degrees C and 71% related at 75 degrees C; it was 75% related to the type strain N. elongata subsp. glycolytica at 60 degrees C and was 66% related at 75 degrees C. DNAs from CDC group EF-4, K. denitrificans, and CDC group M-5 were all less than 14% related to CDC group M-6 at 75 degrees C. The DNA relatedness data showed conclusively that all the M-6 strains belong in the species N. elongata. M-6 is different from N. elongata subsp. elongata in that M-6 reduces nitrate and sometimes weakly acidifies D-glucose, and it is different from N. elongata subsp. glycolytica in that it reduces nitrate and is negative for glucose and catalase. Because of the apparent clinical significance of M-6 compared with the clinical significance of N. elongata subsp. elongata and N. elongata subsp. glycolytica and the ease in distinguishing it biochemically, we propose M-6 as a third subspecies of N.elongata, N. elongata subsp. nitroreducens subsp. nov.

Adult↗
PubMed1990

Biochemical identification of Aeromonas genospecies isolated from humans.

One hundred phenotypic characteristics were determined for 138 clinical and environmental Aeromonas strains. Cluster analysis revealed three major phenons equivalent to the A. hydrophila, A. caviae, and A. sobria groups, each of which contained more than one genospecies and more than one named species. An excellent correlation was found between phenotypic identification and classification based on DNA relatedness. DNA hybridization groups within each of the phenotypic groups were also separable by using a few biochemical characteristics. Key tests were production of acid from or growth on D-sorbitol (which separated DNA hybridization group 3 from groups 1 and 2 within the A. hydrophila phenogroup), growth on citrate (which essentially separated DNA hybridization group 4 from groups 5A and 5B within the A. caviae phenogroup), and growth on DL-lactate (which separated DNA hybridization group 1 from groups 2 and 3 within the A. hydrophila phenogroup as well as group 5A from groups 4 and 5B within the A. caviae phenogroup). All except one strain in the A. sobria phenogroup belonged to DNA hybridization group 8. DNA hybridization groups were not equally distributed among clinical and environmental isolates, suggesting that strains of certain DNA hybridization groups might be less virulent than others.

Aeromonas↗
PubMed1990

Phenotypic characterization, cellular fatty acid composition, and DNA relatedness of aerococci and comparison to related genera.

Aerococci can be misidentified as streptococci, enterococci, pediococci, lactococci, or leuconostocs. To distinguish the genus and determine if another species is needed in the present taxon, we analyzed 37 aerococci for cellular fatty acids and compared them with 377 strains of gram-positive cocci, including the species type strains from each of the related genera. The cellular fatty acid profile of aerococci was distinguishable from other genera. Two relatively novel fatty acids found in the aerococci were identified as C16:1 omega 9c and C16:1 omega 9t. Eleven strains of aerococci (including a strain originally identified as "Gaffkya" species) were chosen for DNA-DNA reassociation studies with the type strain Aerococcus viridans ATCC 11563; DNAs from eight of these strains were more than 75% related to the type strain and had 1 to 4% divergence in related sequences. The remaining three strains were 60 to 70% related to the type strain, had 7 to 11.5% divergence, and may represent a second species, Aerococcus genospecies 2. beta-Glucuronidase, alpha-galactosidase, and beta-galactosidase were useful in characterizing the aerococci.

Chloramphenicol O-Acetyltransferase↗
PubMed1990

Human serum antibody response to the presence of Aeromonas spp. in the intestinal tract.

A bacterial agglutination assay, a toxin-neutralizing assay, and an enzyme-linked immunosorbent assay (ELISA) were used to compare antibodies against intestinal Aeromonas strains in serum samples from healthy carriers (n = 6), from patients with acute (n = 15) or chronic (n = 8) gastroenteritis, from patients with gastroenteritis caused by other enteropathogenic bacteria (n = 3), and from healthy blood donors (n = 50). Evaluation of the bacterial agglutination assay showed that it was not very useful. The sensitivity of the ELISA in patients with acute or chronic aeromonas-associated diarrhea was 30% (7 of 23 patients were positive), whereas the specificity was 74% (13 of 50 healthy donors were positive). Positive results in the ELISA correlated with immunoglobulin M and immunoglobulin G responses to lipopolysaccharides of homologous Aeromonas strains, as determined by gel immunoradioassay and Western immunoblot analysis. The sera showed cross-reactions with heterologous Aeromonas strains and with Escherichia coli strains. The toxin-neutralizing assay was positive in 5 of 11 patients who had developed acute severe diarrhea associated with cytotoxin-producing Aeromonas strains (46% sensitivity), whereas only 3 of 50 healthy donors had low serum titers of cytotoxin-neutralizing antibodies (94% specificity). All five patients were over 60 years of age. Cytotoxin-neutralizing activity was not observed in the sera of other groups of patients with aeromonads in their feces. We concluded that the three different serologic assays were not consonant with one another and that only the toxin-neutralizing assay distinguished patients with acute diarrhea from other groups of patients.

Adolescent↗
PubMed1990

Track structure, lesion development, and cell survival.

A stochastic track-structure-dependent model is presented based on DNA double-strand breaks (DSBs) interacting in a time- and distance-dependent manner, and in competition with DSB repair, to form exchange-type chromosomal aberrations. Many models of cell survival involve estimation of mean numbers of lesions per cell, which is then related to cell survival. Unless this relationship is linear, this implies that a cell responds not to the number of lesions produced in it, but to the mean number of lesions in all the exposed cells; this is clearly unrealistic, particularly for phenomena such as saturation. In contrast to such deterministic approaches, we describe a stochastic model, in which individual cells are considered and exposed to Monte Carlo-generated tracks of various radiations. The elementary sublesions produced (DSBs) diffuse, repair, or interact, forming lesions (chromosomal exchange-type aberrations) in a time- and distance-dependent manner. Results agree well with experiments for survival of synchronous Chinese hamster V-79 cells exposed to X rays and radiations with LETs from 20 to 170 keV/microns. Thus the main features of survival for low-, medium-, and high-LET radiation are understandable in terms of a single approach, the relative responses to different radiations being determined by their different energy deposition patterns.

Cell Survival↗
PubMed1990

The effects of the temporal distribution of dose on oncogenic transformation by neutrons and charged particles of intermediate LET.

The effects of dose rate and dose fractionation on high-LET radiation-induced oncogenic transformation of C3H 10T1/2 cells were examined. Cells were irradiated with graded doses of 5.9-MeV monoenergetic neutrons administered either in single acute exposures (30 mGy/min) or extended over an 8-h period at low dose rates (from 0.21 to 1 mGy/min). Although cell survival studies showed no difference in effect with a change in radiation delivery rate, enhancement of oncogenic transformation occurred when the dose rate was reduced. When the neutron dose was divided into three fractions over 8 h, the biological effect was intermediate between that for the acute and that for the low-dose-rate exposures. Further irradiations were made using deuterons with an LET of 40 keV/microns. The dose-mean lineal energy was comparable to that measured for the 5.9-MeV monoenergetic neutrons. An inverse dose-rate/fractionation effect for the induction of transformation by high-LET deuterons was observed when the time between each of three fractions for a 0.3-Gy total dose was at least 45 min. No further enhancement was seen for longer dose fractionations, suggesting that very long protracted exposures of high-LET radiation would produce no additional enhancement.

Animals↗
PubMed1989

Infection caused by Francisella philomiragia (formerly Yersinia philomiragia). A newly recognized human pathogen.

We evaluated the clinical characteristics of patients with Francisella philomiragia (formerly Yersinia philomiragia) isolated from normally sterile sites. Isolates from 14 patients were received by the Centers for Disease Control between 1975 and 1987: 9 were from blood; 2 from lung biopsies; and 1 each from pleural, peritoneal, and cerebrospinal fluid. Underlying problems included chronic granulomatous disease in 5 patients, near-drowning in 5, and a myeloproliferative disease in 2. All 13 patients for whom records were available had a febrile syndrome compatible with bacterial infection. Pneumonia and fever-bacteremia were the commonest clinical syndromes reported. In 7 cases, F. philomiragia was the only sterile-site isolate, and the clinical syndrome did not resolve without appropriate antibiotics. Familiarity with this organism is important because of its ability to cause serious disease in chronic granulomatous disease and near-drowning patients. Further study may yield new insights into pathogenic and host defense mechanisms.

Adolescent↗
PubMed1989

Phenotypic characterization and DNA relatedness in human fecal isolates of Aeromonas spp.

Phenotypic characteristics were used to identify 189 Aeromonas strains isolated from human feces. One hundred forty-two of these strains were placed in 11 DNA hybridization groups, and the genetic and phenotypic data were compared. According to the criteria of Popoff, 66% of the strains were identified as Aeromonas caviae, 18% were identified as A. sobria, and 16% were identified as A. hydrophila. Some biochemical characteristics differed from the criteria of Popoff; 19 of 40 (48%) of tested strains were encapsulated, 42 of 124 (34%) of A. caviae strains were nonmotile, and all A. sobria strains were resistant to KCN. Gas production from D-glucose was temperature dependent; 11 of 64 (17%) A. hydrophila and A. sobria strains produced gas only at 22 degrees C. Of 142 Aeromonas strains, 57% belonged to hybridization group 4, 25% belonged to group 8, 11% belonged to group 1, 4% belonged to group 5A, 2% belonged to group 3, and 1% belonged to group 2. Of 26 strains phenotypically identified as A. hydrophila, 8 (31%) were in hybridization group 8, which contains strains of the new species A. veronii. It therefore appears that our ability to identify Aeromonas strains phenotypically is not sufficiently specific. Either additional definitive biochemical markers must be found or phenotypic identification, at least for some Aeromonas groups, must be regarded as only presumptive.

Aeromonas↗
PubMed1989

Human disease associated with "Campylobacter upsaliensis" (catalase-negative or weakly positive Campylobacter species) in the United States.

Catalase-negative or weakly positive (CNW) thermotolerant campylobacteria, first isolated from dogs in 1983, were recently recognized as a new species, "Campylobacter upsaliensis," but their association with human illness has not been established. Twelve human isolates received at the Centers for Disease Control between 1980 and 1986 were identified as CNW campylobacteria by biochemical tests, cellular fatty acid composition, and antimicrobial susceptibility patterns. Eleven CNW Campylobacter strains tested by DNA-DNA hybridization (hydroxyapatite method) were all highly related and were related to two "C. upsaliensis" strains at the species level (86% under optimal conditions and 76% under stringent conditions). Clinical information was obtained for 11 human isolates from three stool and eight blood specimens. They were isolated from four female and seven male patients 6.5 months to 83 years of age residing in 10 different states. The patients had a wide spectrum of illnesses. The stool isolates were obtained from two previously healthy persons during episodes of acute gastroenteritis and from one immunocompromised patient with persistent diarrhea and fever. The blood isolates were obtained from two infants with fever and respiratory symptoms; a young woman with a ruptured ectopic pregnancy; three elderly men with underlying chronic diseases; and two immunocompromised adults. In a bactericidal assay to assess sensitivity to serum, seven of eight blood isolates showed some resistance to killing by pooled normal human serum. These observations suggest that "C. upsaliensis" is a potential human pathogen associated with both gastroenteritis and bacteremia in normal hosts and with opportunistic infection in immunocompromised individuals.

Adult↗
PubMed1989

Pasteurella caballi, a new species from equine clinical specimens.

The name Pasteurella caballi is proposed for a group of organisms represented by 29 strains isolated from respiratory and other infections in horses. P. caballi strains are gram-negative, oxidase-positive, nonmotile, fermentative rods with the key characteristics of the genus Pasteurella. These strains differed from other Pasteurella species in that all were aerogenic and catalase negative, and some strains produced acid from myo-inositol and L-rhamnose. The levels of DNA relatedness of 28 P. caballi strains with labeled DNA from the proposed type strain averaged 91 and 85% (hydroxyapatite method at 55 and 70 degrees C). P. caballi was 13 to 53% related to strains representing 22 other species of the family Pasteurellaceae. The guanine-plus-cytosine content of the DNA of four strains was 41 to 42 mol%. The type strain is 83851 (=ATCC 49197).

Animals↗
PubMed1989

"Campylobacter upsaliensis" isolated from cats as identified by DNA relatedness and biochemical features.

Campylobacter spp. were isolated from the feces of 20 (58%) of 53 asymptomatic cats during routine physical examination while the cats were maintained in an accredited quarantine facility. Fifteen of these Campylobacter spp. were identified phenotypically as Campylobacter jejuni, and two were identified as C. coli. DNA-DNA hybridization (hydroxyapatite method) was used to confirm the identification of three thermotolerant catalase-negative isolates. They were 80 to 100% related to each other and to the type strain of "C. upsaliensis" in reassociation reactions under optimal conditions and a stringent hybridization criterion. These strains were 75 to 100% interrelated and less than 12% related to type strains of other Campylobacter species. These strains represent the first reported feline isolate of "C. upsaliensis" and show that cats used in biomedical research can harbor this and other Campylobacter species.

Animals↗
PubMed1989

Capnocytophaga canimorsus sp. nov. (formerly CDC group DF-2), a cause of septicemia following dog bite, and C. cynodegmi sp. nov., a cause of localized wound infection following dog bite.

CDC group DF-2 is the vernacular name given to a slow-growing gram-negative bacterium that causes septicemia and meningitis in humans. Infections frequently (one-third of cases) occur following dog bites or close contact with dogs or occasionally with cats. Splenectomy and alcoholism appear to be strong predisposing factors for DF-2 infection. In addition to 150 DF-2 strains received for identification, we received 9 DF-2-like strains; 6 were isolated from wound or eye infections, 3 of which were associated with dog bites and 1 of which was associated with a cat scratch, and 3 were isolated from dog mouths. The major characteristics of DF-2 include production of acid but no gas from lactose and maltose and usually D-glucose; positive reactions for oxidase, catalase, arginine dihydrolase, gliding motility, and o-nitrophenyl-beta-D-galactopyranoside; growth enhanced by serum and by incubation in a candle jar atmosphere; and negative reactions for sucrose, raffinose, inulin, melibiose, nitrate reduction, indole, and growth on MacConkey agar. DF-2-like strains had the same characteristics, except that acid was formed from sucrose, raffinose, inulin, and melibiose. By the hydroxyapatite method, DNAs from 12 DF-2 strains were 88% related in 60 degrees C reactions and 84% related in 75 degrees C reactions. Related sequences contained 0.5 to 1.5% unpaired bases (divergence). Three DF-2-like strains were 73 to 80% related at 60 degrees C (with 2.0 to 2.5% divergence) and 68 to 75% related at 75 degrees C. The relatedness of DF-2 and DF-2-like strains was 19 to 31% at 60 degrees Celsius and 13 to 19% at 75 degrees Celsius. The relatedness of DF-2 and DF-2-like strains to Capnocytophaga species was 4 to 7%. The DNA relatedness date indicate that eh DF-2 and the DF-2-like strains are separate, previously undescribed species. Both groups are phenotypically and genetically distinct from Capnocytophaga species, although they do share several characteristics with Capnocytophaga species, including cellular morphology, gliding motility, cellular fatty acid composition, enhancement of growth in a candle jar atmosphere, and G+C content. The new species differ from Capnocytophaga species by their positive oxidase and catalase reactions. We chose to avoid creating a new genus and proposed the names Capnocytophaga canimorsus sp. nov. for group DF-2 and C. cynodegmi sp. nov. for the DF-2-like strains.

Adult↗
PubMed1989

Recovery of Pseudomonas gladioli from respiratory tract specimens of patients with cystic fibrosis.

Pseudomonas gladioli was isolated from 11 patients with cystic fibrosis. It resembled Pseudomonas cepacia on the selective and differential medium OFPBL, producing yellow colonies after 48 to 72 h of incubation. Isolates were characterized biochemically, by DNA hybridization, and by cellular fatty acid analysis. A review of the clinical status of selected patients colonized by P. gladioli did not reveal any apparent association of this organism with infectious complications of cystic fibrosis. Thus, the clinical implications may differ depending on which of these two closely related species is reported by laboratories. Determination of the fatty acid profile of isolates by gas chromatography may be a useful adjunct to biochemical characterization as a means of identification. In contrast to P. cepacia, most isolates of P. gladioli contained 3-OH C10:0 fatty acid under the growth conditions used.

Adolescent↗
PubMed1989

CDC group HB-5 as a cause of genitourinary infections in adults.

Isolates from five patients with genitourinary infections diagnosed over a 7-week period were identified as CDC group HB-5. The organisms caused clinical presentations of pelvic inflammatory disease in three women and urethritis in the only male in the series. The remaining patient received surgical treatment for a Bartholin gland abscess. Since the clinical and temporal presentations were remarkable and the questions of sexual mode of transmission and strain relatedness were of concern, the five strains were examined further by multilocus enzyme electrophoresis and ribosomal DNA typing. Overall, the five clinical isolates were more closely related to each other than to the control strains. This is the first report describing genitourinary infections caused by group HB-5. While the pathophysiology of group HB-5 infections remains to be fully elucidated, the possibility that this organism may be sexually transmitted deserves further study.

Abscess↗
PubMed1989

Clinical and epidemiologic aspects of members of Aeromonas DNA hybridization groups isolated from human feces.

Between June 1982 and May 1987 Aeromonas species were isolated from 208 of 34,311 (0.61%) fecal samples submitted to a Regional Public Health Laboratory in The Netherlands. Aeromonas isolates were found most frequently in summer and rarely in winter. Of 169 Aermonas isolates that were available for further study, 19% were isolated from patients with a mixed infection, 5% from patients with underlying diseases, and 15% from patients who used medication that could predispose the intestinal tract to colonization with Aeromonas species. Aeromonas species that produced cytotoxins to Vero cells (cytotoxigenic) were found in hybridization groups 1 (11% of all isolates), 2 (1%), 3 (2%), and 8 (25%) and were identified phenotypically as A. hydrophila or A. sobria. Aeromonas species that did not produce cytotoxins to Vero cells (noncytotoxigenic) were found in hybridization groups 4 (57%) and 5A (4%) and were identified phenotypically as A. caviae. Distribution of Aeromonas species by age showed a predominance of noncytotoxigenic strains in children under the age of 5 years (46% of all noncytotoxigenic strains), while cytotoxigenic strains were mainly cultured from patients aged 50 years or older (54% of all cytotoxigenic strains). Significant correlations were found between cytotoxigenic strains and hospitalization, foreign travel, and contact with surface water. Cytotoxigenic strains were isolated significantly more often than noncytotoxigenic strains from patients with diarrhea, but in a multivariate analysis including age, previous medication, underlying disease, and foreign travel, this association was not significant.

Aeromonas↗