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Biomedical subjects

J M Janda

Publications and source records attributed to J M Janda.

At least 73 records · Page 4Linked to original sources
PubMed1991

Biochemical and genetic characterization of autoagglutinating phenotypes of Aeromonas species associated with invasive and noninvasive disease.

The genetic characteristics and biochemical and structural properties of a number of autoagglutinating (AA) strains of Aeromonas associated with invasive and noninvasive disease in humans and infections in animals and from environmental sources were investigated. Of 27 strains analyzed by multilocus enzyme typing and DNA hybridization studies, 25 (93%) were confirmed to belong to either hybridization group 1 (phenospecies and genospecies Aeromonas hydrophila) or 8 (phenospecies Aeromonas sobria; genospecies Aeromonas veronii). Further analysis of 19 of these strains indicated that four major groups could be identified on the basis of serologic and surface characteristics, protein and lipopolysaccharide composition, and virulence properties; these groupings held true regardless of the site of isolation or disease process involved. The major AA+ group identified was serogroup O:11, whose strains possessed an S layer, were resistant to the bactericidal activity of normal serum, and were pathogenic in mice. The results suggest a set of useful phenotypic and structural markers for identification of specific subsets of mesophilic Aeromonas involved in a wide range of infections in the animal kingdom.

Aeromonas↗
PubMed1991

Recent advances in the study of the taxonomy, pathogenicity, and infectious syndromes associated with the genus Aeromonas.

Over the past decade, the emergence of Aeromonas species as bona fide human pathogens and their probable role as etiologic agents of bacterial gastroenteritis have resulted in an explosion of scientific interest in the genus. Major accomplishments occurring in this field during that interval include a more refined taxonomy, identification of new cell-associated factors (surface layers, pili), and the molecular analysis of selected extracellular gene products that may play a critical role in pathogenesis (hemolysins, enterotoxins). This review provides an updated overview of recent systematic, clinical, and pathophysiologic advances and defines key areas of medical and scientific interest in which major questions remain unanswered.

Aeromonas↗
PubMed1991

Penetration and replication of Edwardsiella spp. in HEp-2 cells.

The ability of 22 Edwardsiella strains to penetrate and replicate in cultured epithelial cells was initially evaluated by light microscopy methods and by the recovery of gentamicin-resistant (Gmr) bacteria from the Triton X-100 cell lysates of HEp-2-infected monolayers. Giemsa-stained HEp-2 cells revealed the presence of numerous internalized bacteria 3 h postinfection, often appearing as parallel rows of replicated bacteria within the cytosol and sometimes obliterating the cytoplasm because of the large numbers of bacilli present. Invasive bacteria were also sometimes found within cytoplasmic vacuoles in infected cells; thin-section electron micrographs of HEp-2-infected cells supported these conclusions. Results of light microscopy studies and cell lysate assays indicated that most Edwardsiella tarda (92%) and some Edwardsiella hoshinae strains were invasion positive on one or more occasions, while Edwardsiella ictaluri isolates were uniformly negative. HEp-2 invasion by E. tarda was a microfilament-dependent (cytochalasin B- and D-sensitive) process, with maximum numbers of Gmr CFU recorded between 3 and 6 h postinfection. The small percentage (0.01 to 1.0%) of the challenge inoculum recoverable as Gmr progeny 3 to 6 h postinfection was attributed to a strong cell-associated (not filterable) hemolysin that was produced by a majority (85%) of the E. tarda strains but not by E. ictaluri and only minimally by E. hoshinae. This cytolysin/hemolysin was responsible for the toxic effects observed in HEp-2 cells during the infection-replication process of edwardsiellae and appears to play a role in the release of internalized and replicated bacteria from infected cells. The results suggest an invasion strategy with some similarities to and differences from those of other recognized enteroinvasive pathogens.

Cells, Cultured↗
PubMed1991

Laboratory investigations on the low pathogenic potential of Plesiomonas shigelloides.

The pathogenic properties of 16 Plesiomonas shigelloides strains recovered from humans with extraintestinal and intestinal illnesses, infected animals, and environmental sources were investigated. Most strains possessed a high cell charge and low surface hydrophobicity analogous to those of Shigella spp.; additionally, serogroup O:17 strains reacted with Shigella group D antisera. However, unlike the shigellae, P. shigelloides strains did not universally bind Congo red, were noninvasive in HEp-2 cell assays, and did not produce a Shiga-like toxin on Vero cells. On HEp-2, Y1, and possibly Vero cells, a low-level cytolysin was consistently produced by all 16 P. shigelloides strains when grown in either Evan Casamino Acids-yeast extract or Penassay broth. The median 50% lethal dose for all 16 P. shigelloides strains in outbred Swiss Webster mice was 3.5 x 10(8) CFU (range, 3.2 x 10(7) to greater than 1 x 10(9) CFU). Animal pathogenicity did not correlate with cytolysin expression, possession of a greater than or equal to 120-MDa plasmid, protein profile, or resistance to complement-mediated lysis. No strain analyzed produced siderophores or a heat-stable enterotoxin. The results suggest that members of the genus Plesiomonas have an overall low pathogenic potential, irrespective of the site of isolation or phenotypic, serologic, or surface properties shared with other traditional enteropathogens.

Animals↗
PubMed1991

Aeromonas trota sp. nov., an ampicillin-susceptible species isolated from clinical specimens.

Previous DNA hybridization studies established 12 Aeromonas genospecies, from which nine phenotypic species have been proposed: Aeromonas hydrophila, A. sobria, A. caviae, A. media, A. veronii, A. schubertii, A. salmonicida, A. eucrenophila, and A. jandaei. We have delineated a new Aeromonas genospecies, A. trota, on the basis of 13 strains isolated primarily from fecal specimens from southern and southeastern Asia. All strains were highly related to the proposed type strain, AH2 (ATCC 49657T): 51 to 100% (60 degrees C) and 49 to 99% (75 degrees C), with 0.2 to 2.2 divergence. AH2 was only 16 to 41% (60 degrees C) related to all other Aeromonas type strains and DNA group definition strains. The unique profile of A. trota includes negative reactions for esculin hydrolysis, arabinose fermentation, and the Voges-Proskauer test, positive reactions for cellobiose fermentation, lysine decarboxylation, and citrate utilization, and susceptibility to ampicillin, as determined by the broth microdilution MIC method and the Bauer-Kirby disk diffusion method (10 micrograms). Nine of the A. trota strains were from a single study of 165 geographically diverse aeromonads. This finding questions the efficacy of screening fecal specimens for Aeromonas spp. with ampicillin-containing media and suggests a previously unrecognized prevalence of this new species.

Aeromonas↗
PubMed1991

Genotypic identification of pathogenic Mycobacterium species by using a nonradioactive oligonucleotide probe.

Commercial DNA hybridization assays (Syngene, Inc., San Diego, Calif.) utilizing alkaline phosphatase-labeled oligonucleotide probes for the identification of Mycobacterium tuberculosis complex and M. avium complex (MAC) were evaluated with 261 isolates of mycobacteria. On the basis of biochemical criteria, the test for MAC was 98% specific and more sensitive (95 of 99, 95%) than Gen-Probe (88 of 99, 89% sensitivity); the major difference in sensitivity noted between the two systems was related to the hybridization of seven MAC strains to the SNAP X probe. The M. tuberculosis complex probe correctly identified all 62 isolates of M. tuberculosis and all 11 isolates of M. bovis, for a sensitivity of 100%. There were two discrepant reactions with mycobacteria other than M. tuberculosis complex isolates.

Bacteriological Techniques↗
PubMed1991

Pathogenic properties of Edwardsiella species.

The pathogenic characteristics of 35 Edwardsiella strains from clinical and environmental sources were investigated. Overall, most Edwardsiella tarda strains were invasive in HEp-2 cell monolayers, produced a cell-associated hemolysin and siderophores, and bound Congo red; many strains also expressed mannose-resistant hemagglutination against guinea pig erythrocytes. Edwardsiella hoshinae strains bound Congo red and were variable in their invasive and hemolytic capabilities while Edwardsiella ictaluri strains did not produce either factor; neither E. hoshinae nor E. ictaluri expressed mannose-resistant hemagglutination nor elaborated siderophores under the tested conditions. Selected strains of each species tested for mouse lethality indicated strain variability in pathogenic potential, with E. tarda strains being the most virulent; 50% lethal doses in individual strains did not correlate with plasmid content, chemotactic motility, serum resistance, or expression of selected enzyme activities. The results suggest some potential important differences in pathogenic properties that may help explain their environmental distribution and ability to cause disease in humans.

Animals↗
PubMed1990

In vitro susceptibilities of Plesiomonas shigelloides to 24 antibiotics and antibiotic-beta-lactamase-inhibitor combinations.

The antibiotic susceptibilities of 29 isolates of Plesiomonas shigelloides were studied with 24 antibiotics and antibiotic-inhibitor combinations. Results indicated that all isolates were susceptible to the cephalosporins, penicillins combined with a beta-lactamase inhibitor, aztreonam, and ciprofloxacin. Most isolates were resistant to the penicillins, possibly via production of a penicillinase.

Anti-Bacterial Agents↗
PubMed1990

Electrophoretic analysis of the surface components of autoagglutinating surface array protein-positive and surface array protein-negative Aeromonas hydrophila and Aeromonas sobria.

The protein and lipopolysaccharide (LPS) compositions of 10 autoagglutinating Aeromonas hydrophila and Aeromonas sobria strains were studied; one group consisted of five serogroup O:11 strains that contained an S layer, while a second group was composed of diverse serogroups that were S layer negative by transmission electron microscopy. All serogroup O:11 strains were found to contain a predominant 52,000- to 54,000-molecular-weight protein that was present on both whole-cell and outer membrane protein profiles; this protein was found to be glycine extractable under low-pH (pH 4) conditions and was identified as the surface array protein. LPS analysis revealed that all O:11 strains exhibited homogeneous-length O-polysaccharide side chains characterized primarily by two or three major bands. In contrast, S-layer-negative autoagglutinating strains of other serogroups lacked this predominant surface array protein, and silver stain analysis of LPS indicated that such profiles mainly consisted of core antigens and were deficient in or devoid of O-polysaccharide side chains. These collective results offer potential explanations for observed differences between these two groups in virulence, disease spectrum, and pathogenic properties.

Aeromonas↗
PubMed1990

Epidemiologic investigations of Yersinia enterocolitica and related species: sources, frequency, and serogroup distribution.

During an 11-year period (1978 to 1989), over 300 strains of Yersinia spp. (excluding Y. pestis and Y. pseudotuberculosis) were recovered from a variety of gastrointestinal and extraintestinal sites in patients in California. Over the 11-year period, Y. enterocolitica serogroup O:3 predominated, although a shift in the relative frequency of this serogroup was observed during this interval, increasing dramatically during the years 1984 to 1989. Of the remaining Y. enterocolitica isolates, over 40% were identified as belonging to serogroups generally considered to be nonpathogenic, although many of these isolates were recovered in association with milder cases of gastroenteritis. The results suggest a changing and expanding spectrum of Y. enterocolitica serogroups associated with various gastrointestinal and systemic infections.

California↗
PubMed1990

Isolation and identification of autoagglutinating serogroup O:11 Aeromonas strains in the clinical laboratory.

We evaluated the extent to which serogroup O:11 Aeromonas strains could be recovered from both clinical and environmental specimens and the cultural parameters that affected the phenotypic marker (autoagglutination) associated with this group. Of over 200 Aeromonas strains screened, serogroup O:11 was identified only among the phenospecies A. hydrophila and A. sobria and was associated with clinical isolates more frequently than with environmental strains. Blood and wound isolates accounted for almost 50% of all O:11 strains identified. The autoagglutination phenotype associated with O:11 strains could be detected in most commercial liquid media, under a wide range of growth temperatures, and within 15 min of incubation at 100 degrees C. The results suggest that clinical laboratories can recognize this important group of Aeromonas strains by two simple tests.

Aeromonas↗
PubMed1990

Value of the O-nitrophenyl-beta-D-galactopyranoside test to differentiate among the aerobic actinomycetes.

A comparative study to determine beta-D-galactosidase activity among 171 strains of aerobic actinomycetes (including mycobacteria and rhodococci) was performed by using two growth media and four O-nitrophenyl-beta-D-galactopyranoside (ONPG) substrates. The ONPG test was found to be a valuable screening test to differentiate between the ONPG-positive Nocardia spp. and the rapidly growing ONPG-negative mycobacteria and rhodococci. However, ONPG results varied significantly depending on the growth medium and test substrate used.

Actinomycetales↗
PubMed1989

Mycobacterium avium and Mycobacterium intracellulare infections in patients with and without AIDS.

A genetic probe (Gen-Probe) was used to evaluate potential epidemiologic and susceptibility differences of Mycobacterium avium complex (MAC) strains isolated from 154 patients with and without the acquired immunodeficiency syndrome (AIDS). Genetic analysis revealed that 98% of the 45 patients with AIDS harbored only M. avium regardless of the anatomic or geographic source of the isolate; in contrast, approximately 40% of MAC isolates recovered from 109 patients without AIDS were M. intracellulare. Most M. intracellulare of respiratory origin recovered from patients without AIDS were involved in infectious processes. When 95 MAC isolates (M. avium, n = 53; M. intracellulare, n = 42) were evaluated for in vitro susceptibility to primary or secondary antimycobacterial drugs, significant differences were noted. M. intracellulare was more susceptible to streptomycin, rifampin, and ethambutol than M. avium; the converse was true for ethionamide. The results of this study suggest potentially important differences in disease spectrum and in vitro susceptibility profile for M. avium and M. intracellulare.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Surface properties and ultrastructure of Edwardsiella species.

Twenty-two strains of Edwardsiella representing the three currently recognized species were evaluated for surface characteristics and ultrastructural morphology. All isolates tested possessed a high surface cell charge as detected by DEAE-cellulose chromatography; surface hydrophobicity was variable and strain but not species dependent. Two major types of adhesins detected by hemagglutination assays were identified: one was inhibited by D-mannose (mannose-sensitive hemagglutinin) and found on all three species, and a second was not inhibited by D-mannose (mannose-resistant hemagglutinin) and was principally associated with Edwardsiella tarda. The results of physiologic and ultrastructural studies suggest that both hemagglutinins are afimbrial adhesin proteins. The results of these studies suggest that there are a number of distinct surface and ultrastructural properties associated with each of the three Edwardsiella species.

Chromatography, DEAE-Cellulose↗
PubMed1989

Species identification of Aeromonas strains based on carbon substrate oxidation profiles.

Twenty clinical strains each of Aeromonas hydrophila, Aeromonas caviae, and Aeromonas sobria were evaluated for their abilities to oxidize one or more of 95 carbon sources on a GN Microplate (BIOLOG, Hayward, Calif.). Nine substrates yielded good, discriminatory values for the three species tested. The panel appears to be useful for the species identification of Aeromonas isolates originating from human material.

Aeromonas↗
PubMed1988

Current perspectives on the epidemiology and pathogenesis of clinically significant Vibrio spp.

Recent taxonomic advances have now implicated several different Vibrio species as human pathogens. While the most common clinical presentation of Vibrio infection continues to be gastroenteritis, an increasing number of extraintestinal infections are being reported, particularly in immunocompromised individuals. Detection of Vibrio infections requires a good clinical history and the use of appropriate isolation and identification procedures by the laboratory to confirm illnesses attributed to Vibrio species. Except for Vibrio cholerae O1 and Vibrio parahaemolyticus, there is little direct evidence linking the production of a myriad of cell-associated or extracellular factors produced by each species with human disease and pathogenesis. Many questions regarding pathogenic Vibrio species remain unanswered, including their frequency and distribution in environmental specimens (water, shellfish), infective doses, virulence potential of individual isolates, and markers associated with such strains.

Epidemiologic Methods↗