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Biomedical subjects

J M Janda

Publications and source records attributed to J M Janda.

At least 55 records · Page 3Linked to original sources
PubMed1994

The susceptibility of S-layer-positive and S-layer-negative Aeromonas strains to complement-mediated lysis.

Forty strains of Aeromonas hydrophila and Aeromonas veronii recovered from invasive and non-invasive infections were tested for their susceptibility to complement-mediated lysis by 65% pooled human serum (PHS). Based upon the results of this assay, two major populations could be defined. The first group (n = 20) consisted of serogroup O:11 strains, all of which possessed a paracrystalline surface layer (S layer); all of these strains were refractory to the bactericidal activity of 65% PHS with the exception of A. hydrophila strain AH-121, which was composed of mixed subpopulations of serum-susceptible and serum-resistant clones. A second collection of isolates (n = 20), all of which were S-layer-negative, contained a subgroup of strains (n = 7) that were highly susceptible to complement-mediated lysis, showing a greater than 100-fold reduction of viable progeny within 30 min of exposure to 65% PHS. Serum-resistant strains from both groups could not be lysed by exposure of bacterial cells to polyclonal somatic or whole cell antisera or to 30 micrograms ml-1 of polymyxin B nonapeptide prior to challenge with 65% PHS. Analysis of selected serum-resistant and serum-susceptible strains from both groups showed that all isolates activated the complement pathway and most bound C3b to the cell surface, indicating that the inability of complement to lyse serum-resistant strains was related to a defect in the terminal portions of the complement pathway.(ABSTRACT TRUNCATED AT 250 WORDS)

Aeromonas↗
PubMed1994

Case of Aeromonas veronii (DNA group 10) bacteremia.

We describe the first case report of bacteremia due to Aeromonas veronii biotype veronii. The infection occurred in a 77-year-old man suffering from multiple underlying conditions which included cancer of the sigmoid colon. Because of the unusual biochemical phenotype of this group (ornithine decarboxylase positive), it was originally identified as Vibrio cholerae.

Aeromonas↗
PubMed1994

Escherichia coli O157:H7 generates a unique biochemical profile on MicroScan conventional gram-negative identification panels.

More than 90% of the strains of Escherichia coli O157:H7 that were identified on a MicroScan gram-negative dried conventional (overnight) panel gave one of two unique biochemical profile numbers that were not detected in other d-sorbitol-negative E. coli or in other strains isolated from pathogenic processes. This suggests that the panel has the capability of being used as a preliminary screening tool for O157:H7 strains involved in hemorrhagic colitis when MacConkey-sorbitol agar is not available.

Bacterial Typing Techniques↗
PubMed1994

Biochemical identification of citrobacteria in the clinical laboratory.

We biochemically identified 235 Citrobacter strains to the species level on the basis of the recently proposed taxonomic changes of Brenner et al. (D. J. Brenner, P. A. D. Grimont, A. G. Steigerwalt, G. R. Fanning, E. Ageron, and C. F. Riddle, Int. J. Syst. Bacteriol. 43:645-658, 1993). Citrobacter isolates were initially identified as C. koseri or as members of the C. freundii complex or C. amalonaticus group on the basis of indole production, formation of H2S, malonate utilization, and acid production from D-arabitol and adonitol. On the basis of the results of these tests, 68% of the Citrobacter strains were identified as members of the C. freundii complex, 25% were C. koseri, and 8% were members of the C. amalonaticus group. By using a 15-test system recently proposed by Brenner et al. (D. J. Brenner, P. A. D. Grimont, A. G. Steigerwalt, G. R. Fanning, E. Ageron, and C. F. Riddle, Int. J. Syst. Bacteriol. 43:645-658, 1993) to help identify new species in the C. freundii complex and C. amalonaticus group, 81% of the C. freundii complex strains and 100% of the C. amalonaticus strains could be definitively assigned to one of the previously established or recently designated species or hybridization groups of the genus Citrobacter. Within the C. freundii complex, C. freundii predominated overall (37%), followed by C. youngae (24%), C. braakii (13%), and C. werkmanii (6%). Only one strain each of C. sedlakii and Citrobacter DNA group 11 was identified in this study. Among C. amalonaticus complex members, all were identified as C. amalonaticus with the singular exception of one fecal isolate of C. farmeri. C. freundii and C. koseri were the two Citrobacter species most commonly (80 of 93 [86%]) isolated from extraintestinal sources (genitourinary tract, wounds, blood).

Bacterial Typing Techniques↗
PubMed1993

Expression of an iron-regulated hemolysin by Edwardsiella tarda.

The ability of Edwardsiella tarda to hemolyse red blood cells was investigated. Most E. tarda strains (> 80%) produced a hemolysin when assayed by either an agar overlay or contact-dependent hemolysis technique. This activity was cell-associated (CAH) and not released into the culture supernatant under routine conditions. When quantified, E. tarda strains significantly produced 30-40-fold higher levels of hemolytic activity against guinea pig, sheep, or rabbit erythrocytes than either E. hoshinae or E. ictaluri. When grown under iron restricted-conditions in the presence of ethylenediamine di(o-hydroxyphenylacetic acid), hemoglobin, hematin and hemin were found to stimulate growth in both liquid and agar bioassays. Hemolysin activity could be released from selected E. tarda strains when grown in L broth supplemented with EDDA; hemolytic activity was 3- to > 40-fold under these conditions when compared to L broth alone. Preliminary characterization of the hemolysin of strain ET-13 indicates that it is a heat-labile protein with active sulphydryl and thiol groups. These results indicate that, in addition to its invasive capabilities, E. tarda produces a hemolysin which is at least partially regulated by the relative availability of iron and may play a role in human disease.

Culture Media↗
PubMed1993

Infections associated with the genus Edwardsiella: the role of Edwardsiella tarda in human disease.

The role of the genus Edwardsiella in human illness is reviewed. Of the three recognized species, only Edwardsiella tarda has been demonstrated to be pathogenic for humans. Chief infections associated with this species include bacterial gastroenteritis, wound infections such as cellulitis or gas gangrene associated with trauma to mucosal surfaces, and systemic disease such as septicemia, meningitis, cholecystitis, and osteomyelitis. Risk factors that are associated with E. tarda infections include exposure to aquatic environments or exotic animals (e.g., reptiles or amphibia), preexisting liver disease, conditions leading to iron overload, and dietary habits (e.g., raw fish ingestion). Although studies indicate that this bacterium is susceptible to most commonly prescribed antibiotics, fatal gastrointestinal and extraintestinal infections have been described.

Adolescent↗
PubMed1993

Sucrose-positive Edwardsiella tarda mimicking a biogroup 1 strain isolated from a patient with cholelithiasis.

An unusual strain of Edwardsiella tarda mimicking a biogroup 1 isolate was recovered in a mixed infection from a woman suffering from cholelithiasis. Rare biochemical characteristics (e.g., H2S negativity) originally detected were related to an unusual biochemical property in this species, sucrose fermentation; other points of interest regarding this strain included the site of isolation (bile) and the failure of this isolate to produce many of the in vitro virulence markers associated with E. tarda.

Aged↗
PubMed1993

Expression of hemolytic activity by Plesiomonas shigelloides.

More than 90% of the Plesiomonas shigelloides strains that we tested produced a beta-hemolysin, as judged by the results of agar overlay and contact-dependent hemolysis assays. The hemolysin was cell associated, was active against the erythrocytes of various animal species, and was synthesized at both 25 and 35 degrees C. Activity was lost after thermal or proteolytic treatments or after preincubation in the presence of gentamicin; hemolytic activity did not appear to correlate with the previously established 50% lethal doses for seven of these strains. The hemolysin may play a role in iron acquisition in vivo via the lysis of erythrocytes, liberating hemoglobin, or, alternatively, may be involved in gastrointestinal disease.

Diarrhea↗
PubMed1992

Preliminary studies on the use of carbon substrate utilization patterns for identification of Brucella species.

A commercial system (Biolog, Hayward, CA) that uses reduction of an indicator dye to determine the oxidation of 95 different carbon substrates contained in a defined minimal medium was tested with 35 isolates of Brucella spp. to determine if the system could be used in place of respirometric methods to identify species. Of 95 substrates contained in this system, three were oxidized by all the Brucella strains tested, 48 were oxidized by none of the strains tested, and 44 were oxidized differentially. Brucella melitensis, B. abortus, and B. suis could be distinguished from each other on the basis of their oxidation reactions in seven in these substrates; epidemiologically related strains could not be unambiguously differentiated. This carbon substrate utilization method may prove to be a useful alternative to respirometry as a means to identify strains of Brucella spp. to species level, provided that personnel are protected from exposure to this highly infectious agent.

Bacteriological Techniques↗
PubMed1992

Immunochemical analysis and possible biological role of an Aeromonas hydrophila surface array protein in septicaemia.

The biochemical, immunological, and biological properties of an S layer purified from an Aeromonas hydrophila strain (AH-342) involved in a case of bacteraemia were investigated. The S layer selectively removed from the cell surface was composed of a single acidic (pI 4.56) protein subunit (surface array protein, SAP) with a molecular mass of approximately 52 kDa. Amino acid analysis of this 52 kDa protein indicated a molecule composed of 498 amino acids with 46% hydrophobic residues. No cysteine residues were detected. The first 35 residues of the N-terminus were sequenced by Edman degradation; only 4-24% homology was noted between this sequence and those previously published for SAPs of Aeromonas salmonicida (A450) and a strain of A. hydrophila (TF7) originally isolated from a moribund fish. Polyclonal antibodies raised against AH-342 SAP were genospecific, reacting only against S layers produced by A. hydrophila strains and not those from Aeromonas veronii. Acute serum from the bacteraemic patient from whom AH-342 was isolated reacted strongly with the SAP of AH-342 in immunoblot studies. Purified SAP, when intraperitoneally co-inoculated with SAP- strains of A. hydrophila into Swiss-Webster mice, could reduce the 50% lethal dose by approximately 30-70 fold. The results suggest that the SAP of A. hydrophila strains may play an important role in systemic dissemination after invasion through the gastrointestinal mucosa.

Aeromonas hydrophila↗
PubMed1992

Structural and pathogenic properties of Aeromonas schubertii.

We investigated the phenotypic, structural, and pathogenic properties of 11 Aeromonas schubertii strains recovered from extraintestinal sites. Most A. schubertii strains were autoagglutination positive, possessed a high surface charge but low hydrophobicity, and fell into one or two biogroups on the basis of carbon substrate utilization patterns. Fatty acid methyl ester analysis of A. schubertii revealed this species to contain a relatively high percentage of branched fatty acids (i-13:0, i-15:0, i-17:1, i-17:0) compared with A. hydrophila. Immunologic and biochemical analysis of the lipopolysaccharides of A. schubertii strains allowed for two groups to be distinguished, namely, (i) a collection of six strains belonging to serogroup O:11 that possessed a characteristic homogeneous O polysaccharide side chain profile by silver staining and immunoblotting techniques and (ii) a second antigenically diverse group (five strains) that either exhibited a heterogeneous side chain profile or were side chain deficient. A, schubertii O:11 strains were all found to contain a 55-kDa major protein associated with the outer membrane fraction which was glycine-hydrochloride extractable; non-O:11 strains did not harbor a similar protein molecule. Screening of A. schubertii strains for reputed virulence factors indicated (i) that slightly more than half of the isolates produce an apparent contact-dependent hemolysin that is not cell associated or released extracellularly, (ii) a potent cytotoxin active against HEp-2 cells that is devoid of hemolytic activity, and (iii) lack of enterotoxigeniclike activity as determined by suckling mouse assays. All A. schubertii strains were pathogenic for mice as determined by 50% lethal dose assays, although no single factor correlated with mouse pathogenicity.

Aeromonas↗
PubMed1992

Association of an important Neisseria species, Neisseria elongata subsp. nitroreducens, with bacteremia, endocarditis, and osteomyelitis.

We retrospectively analyzed epidemiologic information associated with 22 cultures of Neisseria elongata subsp. nitroreducens (formerly CDC group M-6) submitted to the Microbial Diseases Laboratory, California Department of Health Services, Berkeley, over a 16-year period. The most common illnesses noted with this bacterium were endocarditis, bacteremia, and osteomyelitis. Risk factors associated with N. elongata subsp. nitroreducens infection included dental manipulations and/or a previous history of endocarditis, valve damage, or rheumatic heart disease.

Adult↗
PubMed1992

Identification of Aeromonas strains to the genospecies level in the clinical laboratory.

One hundred thirty-three strains of Aeromonas (human, n = 102; animal, n = 16; environmental, n = 15) previously identified to the DNA group level by molecular methods were biochemically analyzed for 58 properties. On the basis of the use of between 9 and 16 selected tests, 132 of the 133 strains (99%) could be assigned to their correct hybridization group using this biochemical scheme. The results suggest a feasible approach for identifying aeromonads to genospecies level under appropriate conditions.

Aeromonas↗
PubMed1991

The pathogenicity of Aeromonas strains relative to genospecies and phenospecies identification.

The relative pathogenicity of 80 Aeromonas strains typed by biochemical (phenospecies) and genetic (genospecies) methods was assessed by determining the 50% lethal dose for each isolate in Swiss-Webster mice by intraperitoneal injection. Overall, the maximum difference in virulence potential observed between the least and most pathogenic strains was a four log (10,000-fold) difference. Results according to phenospecies designation supported previous investigations indicating that both A. hydrophila and A. sobria are inherently more pathogenic for mice than A. caviae. According to genospecies designation, the relative virulence of individual groups in decreasing order was as follows: HG 9 (A. jandaei) greater than HG 1 (A. hydrophila) and HG 12 (A. schubertii) greater than HG 10 (A. veronii biotype veronii) greater than HG 8 (A. veronii biotype sobria) greater than HG 11 (unnamed) greater than HG 2 (unnamed) greater than HG 3 (A. salmonicida), HG 4 (A. caviae) and HG 6 (A. eucrenophila) greater than HG 5 (A. media) greater than HG 7 (A. sobria).

Aeromonas↗
PubMed1991

Characterization of classic and atypical serogroup O:11 Aeromonas: evidence that the surface array protein is not directly involved in mouse pathogenicity.

A number of different techniques were used to analyse classic and atypical serogroup O:11 Aeromonas isolates. Five of seven atypical O:11, S layer-negative strains lacking a homogeneous LPS side-chain pattern exhibited varying degrees of mouse pathogenecity. One virulent atypical strain (AH-77) synthesized a surface array protein (SAP) but was unable to anchor it to the cell surface in an intact form, presumably due to a defect in its LPS architecture. Proteinase K digestion to remove the SAP, or growth at elevated temperatures (42 degrees C) to reduce the proportion of SAP synthesized from classic O:11 S layer-positive strains, did not alter their LD50 values in outbred mice. In addition, a spontaneous mutant, AS-180-1, that was S layer-negative was as virulent as the parental S layer-positive strain in the mouse model. These results suggest neither the SAP nor the characteristic serogroup O:11 homogeneous LPS side-chain pattern are directly involved in mouse pathogenicity.

Aeromonas↗