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At least 19 recordsLinked to original sources
PubMed2005

E. coli virulence factor hemolysin induces neutrophil apoptosis and necrosis/lysis in vitro and necrosis/lysis and lung injury in a rat pneumonia model.

Enteric gram-negative bacilli, such as Escherichia coli are the most common cause of nosocomial pneumonia. In this study a wild-type extraintestinal pathogenic strain of E. coli (ExPEC)(CP9) and isogenic derivatives deficient in hemolysin (Hly) and cytotoxic necrotizing factor (CNF) were assessed in vitro and in a rat model of gram-negative pneumonia to test the hypothesis that these virulence factors induce neutrophil apoptosis and/or necrosis/lysis. As ascertained by in vitro caspase-3/7 and LDH activities and neutrophil morphology, Hly mediated neutrophil apoptosis at lower E. coli titers (1 x 10(5-6) cfu) and necrosis/lysis at higher titers (> or =1 x 10(7) cfu). Data suggest that CNF promotes apoptosis but not necrosis or lysis. We also demonstrate that annexin V/7-amino-actinomycin D staining was an unreliable assessment of apoptosis using live E. coli. The use of caspase-3/7 and LDH activities and neutrophil morphology supported the notion that necrosis, not apoptosis, was the primary mechanism by which neutrophils were affected in our in vivo gram-negative pneumonia model using live E. coli. In addition, in vivo studies demonstrated that Hly mediates lung injury. Neutrophil necrosis was not observed when animals were challenged with purified lipopolysaccharide, demonstrating the importance of using live bacteria. These findings establish that Hly contributes to ExPEC virulence by mediating neutrophil toxicity, with necrosis/lysis being the dominant effect of Hly on neutrophils in vivo and by lung injury. Whether Hly-mediated lung injury is due to neutrophil necrosis, a direct effect of Hly, or both is unclear.

Animals↗
PubMed2003

Most human isolates of Mycobacterium avium Mav-A and Mav-B are strong producers of hemolysin, a putative virulence factor.

Hemolysin was quantified in 58 isolates of Mycobacterium avium from human, animal, and environmental sources. Human Mav-A and Mav-B isolates were the strongest producers; in contrast, animal and environmental Mav-A isolates and human, animal, and environmental Mav-C organisms were low-level producers. Hemolysin production was not restricted to isolates causing invasive infections.

AIDS-Related Opportunistic Infections↗
PubMed1983

[Relationship between hemolysin and hemolysin-destructive factor activities in Vibrio cholerae of Eltor biovar].

The study of hemolysin activity, hemolysin-destructive factor (HDF) activity and cholerogenicity in 143 Vibrio eltor strains has revealed the existance of close relationship between cholerogenicity and hemolysin production, as well as between cholerogenicity and HDF activity. The negative character of conjugation between the HDF activity and the hemolytic activity of the strains under study has been established, which allows one to suggest the possibility of the regulating action of hemolysin on the synthesis of HDF (enterotoxin).

Animals↗
PubMed1988

Purification of Chironex fleckeri venom components using Chironex immunoaffinity chromatography.

A comparison of the purification of the nematocyst venom of Chironex fleckeri by affinity immunochromatography using 13 different monoclonal antibodies was made. Varying degrees of purification of mouse lethal factor, hemolysin and dermonecrotic factors, as well as antigen positive proteins were achieved with each of the monoclonal antibodies. Although the protein curves of the chromatography were similar, each of the monoclonal antibody columns had a distinctive pharmacological and SDS-PAGE profile. At least two hemolysins (120,000 and 70,000 molecular weight), two dermonecrotic principles (120,000, less than 120,000) and three lethal factors (120,000, 70,000 and 14,500 molecular weight) were detected. The degree to which aggregation and fragmentation affects the molecular weights of these proteins is not known. It appears that multiple pharmacological activities are present within the same molecule since it is only with great difficulty that a pharmacological activity can be assigned to a specific molecular weight.

Animals↗
PubMed2002

Association between the presence of enterococcal virulence factors gelatinase, hemolysin, and enterococcal surface protein and mortality among patients with bacteremia due to Enterococcus faecalis.

The potential virulence factors of enterococci include production of enterococcal surface protein (Esp), gelatinase, and hemolysin. Gelatinase- and hemolysin-producing strains of Enterococcus faecalis have been shown to be virulent in animal models of enterococcal infections. Esp production has been shown to enhance the persistence of E. faecalis in the urinary bladder. We determined the presence of the esp gene and production of gelatinase and hemolysin in 219 E. faecalis isolates from a larger prospective study of 398 patients with enterococcal bacteremia. Thirty-two percent of isolates carried the esp gene, 64% produced gelatinase, and 11% produced hemolysin. There was no significant association between 14-day mortality and any of the markers studied, singly or in combination.

Adolescent↗
PubMed1963

MECHANISM OF ACTION OF STAPHYLOCOCCAL ALPHA-HEMOLYSIN. I. SOME FACTORS INFLUENCING THE MEASUREMENT OF ALPHA-HEMOLYSIN.

Marucci, Americo A. (Upstate Medical Center, Syracuse, N.Y.). Mechanism of action of staphylococcal alpha-hemolysin. I. Some factors influencing the measurement of alpha-hemolysin. J. Bacteriol. 86:1182-1188. 1963.-A kinetic method for the accurate and reproducible measurement of the action of staphylococcal alpha-hemolysin on rabbit erythrocytes is described. The activity of the alpha-hemolysin depends upon the temperature used for measurement. At 37 C the hemolysin lyses cells faster, but it in turn is rather quickly inactivated. At 0 C there is no inactivation, but the rate of lysis is greatly decreased. There is no change in the activity with change in total reaction volume, providing that the concentrations of cells and hemolysin are kept constant. The fraction of rabbit red cells lysed by a given amount of hemolysin in a given time is constant and independent of the total number of cells in the reaction mixture.

Animals↗
PubMed1989

Molecular epidemiology of adhesin and hemolysin virulence factors among uropathogenic Escherichia coli.

The pap, prs, pil, and hly operons of the pyelonephritic Escherichia coli isolate J96 code for the expression of P, F, and type 1 adhesins and the production of hemolysin, respectively; the afaI operon of the pyelonephritic E. coli KS52 encodes an X adhesin. Using different segments of these operons as probes, colony hybridizations were performed on 97 E. coli urinary tract and 40 fecal clinical isolates to determine (i) the presence in the infecting bacteria of nucleotide sequences related to virulence operons, and (ii) the phenotypic properties associated with such sequences. Coexpression of P and F adhesins encoded by pap-related sequences was detected more frequently among isolates from patients with pyelonephritis (32 of 49, 65%) than among those with cystitis (11 of 48, 23%; P less than 0.0001) or from fecal specimens (6 of 40, 15%; P less than 0.0001). Therefore, the expression of both adhesins appears to be critical in the colonization of the upper urinary tract. In contrast, afaI-related sequences were detected significantly more frequently among isolates from patients with cystitis, suggesting that this class of X adhesin may have a role in lower urinary tract infections. Urinary tract isolates differed from fecal isolates by a low incidence of type 1 adhesin expression among pil probe-positive isolates. hly-related sequences were only detected in pap probe-positive isolates. The frequency of hemolysin production among pap probe-positive isolates was not associated with a particular pattern of infection. The distribution of these virulence factors was similar in the presence or absence of reflux, indicating that structural abnormalities of the urinary tract did not facilitate colonization by adhesin-negative isolates.

Adhesins, Escherichia coli↗
PubMed1982

Serum resistance among Escherichia coli strains causing urinary tract infection in relation to O type and the carriage of hemolysin, colicin, and antibiotic resistance determinants.

The sensitivity to normal human serum of 91 smooth strains of Escherichia coli isolated from urinary tract infections was determined. Production of hemolysin, which was common and associated primarily with the types O4, O6, O18, and O75, was significantly correlated with high levels of serum resistance, both within the total population and within individual O types. In contrast, serum resistance was not significantly associated with antibiotic resistance (whether transmissible or not), with colicinogeny in general, or with colicin V production in particular. This indicates that the carriage of R and ColV plasmids, shown previously to be capable of conferring increased levels of serum resistance on individual strains of E. coli isolated from other sources, does not play an important part in determining the serum sensitivity of the E. coli population involved in urinary tract infection.

Anti-Bacterial Agents↗
PubMed1982

Hemolysin plasmid coding for the virulence of a nephropathogenic Escherichia coli strain.

The nephropathogenic Escherichia coli strain P673 was shown to harbor two plasmids with molecular sizes of 70 and 41 megadaltons, respectively. The 70-megadalton plasmid, pCW1, coded for tetracycline resistance, whereas hemolysin production was coded by the 41-megadalton plasmid, pCW2. Plasmid pCW1 proved to be self-transmissible, in contrast to pCW2. Transfer of the hemolysin character was associated with the appearance of a 110-megadalton plasmid, pCW3. The incompatibility of pCW3 with both native plasmids and restriction enzyme analysis led to the conclusion that pCW3 is a cointegrate of pCW1 and pCW2, pCW2, carrying the hemolytic determinant, is involved in the nephropathogenic character of strain P673, because (i) elimination of pCW2 from P673 was associated with a loss of virulence and (ii) the nephropathogenicity of the avirulent mutant could be restored by reintroduction of pCW2 DNA as part of a cointegrate structure.

Animals↗
PubMed1963

Partial purification and properties of two phospholipases of Bacillus cereus.

Slein, Milton W. (U.S. Army Chemical Corps Biological Laboratories, Fort Detrick, Frederick, Md.) and Gerald F. Logan, Jr. Partial purification and properties of two phospholipases of Bacillus cereus. J. Bacteriol. 85:369-381. 1963.-Culture filtrates of Bacillus cereus contain a phosphatasemia factor (PF) that markedly increases blood alkaline phosphatase after intravenous injection into animals, and that releases alkaline phosphatase from epiphyseal bone slices in vitro. Fractionation of culture filtrates of B. cereus with N,N'-diethyl-aminoethyl cellulose results in the separation of two phospholipases, one that has PF activity and one that inhibits PF activity in vitro. Growth of shaken cultures favors accumulation of the inhibitor, whereas static cultures yield more PF. Lethality for mice and hemolysin activity do not appear to be associated with the phospholipase that inhibits PF. The relationship of the lethal and hemolysin factors to the phospholipase that produces phosphatasemia is not clear. The effects of heat, trypsin, lecithin, and antiserum on the phospholipases are reported. The intravenous injection of relatively large amounts of the purified PF resulted in the depletion of bone alkaline phosphatase.

Alkaline Phosphatase↗
PubMed2006

Persistence, transmission, and virulence characteristics of Aeromonas strains in a duckweed aquaculture-based hospital sewage water recycling plant in Bangladesh.

The persistence and transmission of Aeromonas in a duckweed aquaculture-based hospital sewage water treatment plant in Bangladesh was studied. A total of 670 samples from different sites of the hospital sewage water treatment plant, from feces of hospitalized children suffering from diarrhea, from environmental control ponds, and from feces of healthy humans were collected over a period of three years. In total, 1,315 presumptive Aeromonas isolates were biochemically typed by the PhenePlate rapid screening system (PhP-AE). A selection of 90 representative isolates was further analyzed with PhenePlate (PhP) extended typing (PhP-48), fatty acid methyl ester analysis, and amplified fragment length polymorphism (AFLP) fingerprinting. In addition, the prevalence of the putative virulence factors hemolysin and cytotoxin and the presence of the cytolytic enterotoxin gene (AHCYTOEN) were analyzed. Aeromonas was found at all sites of the treatment plant, in 40% of the samples from environmental control ponds, in 8.5% of the samples from hospitalized children suffering from diarrhea, and in 3.5% of samples from healthy humans. A significantly high number of Aeromonas bacteria was found in duckweed, which indicates that duckweed may serve as a reservoir for these bacteria. PhP-AE typing allowed identification of more than 192 distinct PhP types, of which 18 major PhP types (MTs) were found in multiple sites and during several occasions. AFLP fingerprinting revealed the prevalence of genotypically indistinguishable Aeromonas isolates among certain PhP MTs recovered from different sampling occasions and/or at multiple sites. Hemolytic and cytotoxic activities were observed in 43% of the tested strains, whereas 29% possessed the cytolytic enterotoxin gene AHCYTOEN. Collectively, two specific MTs associated with diarrhea were shown to exhibit high cytotoxicity. Furthermore, all tested isolates of these major types were positive for the cytolytic enterotoxin gene. In conclusion, our data indicate that certain phenotypically and genotypically stable clonal lineages of Aeromonas have persisted in the treatment system for a prolonged period and might spread from the hospitalized children suffering from diarrhea to fish produced for human consumption through the sewage water treatment system.

Aeromonas↗
PubMed1983

Transport of hemolysin by Escherichia coli.

The hemolytic phenotype in Escherichia coli is determined by four genes. Two (hlyC and hlyA) determine the synthesis of a hemolytically active protein which is transported across the cytoplasmic membrane. The other two genes (hlyBa and hlyBb) encode two proteins which are located in the outer membrane and seem to form a specific transport system for hemolysin across the outer membrane. The primary product of gene hlyA is a protein (protein A) of 106,000 daltons which is nonhemolytic and which is not transported. No signal peptide can be recognized at its N-terminus. In the presence of the hlyC gene product (protein C), the 106,000-dalton protein is processed to the major proteolytic product of 58,000 daltons, which is hemolytically active and is transported across the cytoplasmic membrane. Several other proteolytic fragments of the 106,000-dalton protein are also generated. During the transport of the 58,000-dalton fragment (and possible other proteolytic fragments of hlyA gene product), the C protein remains in the cytoplasm. In the absence of hlyBa and hlyBb the entire hemolytic activity (mainly associated with the 58,000-dalton protein) is located in the periplasm: Studies on the location of hemolysin in hlyBa and hlyBb mutants suggest that the gene product of hlyBa (protein Ba) binds hemolysin and leads it through the outer membrane whereas the gene product of hlyBb (protein Bb) releases hemolysin from the outer membrane. This transport system is specific for E coli hemolysin. Other periplasmic enzymes of E coli and heterologous hemolysin (cereolysin) are not transported.

Base Sequence↗
PubMed1979

Plasmid cistrons controlling synthesis and excretion of the exotoxin alpha-haemolysin of Escherichia coli.

The synthesis and secretion of the toxic exoprotein alpha-haemolysin of E. coli PM152 is coded by the transmissible plasmid pHly152 (41 x 10(6) dalton) as shown by the transformation of the plasmid DNA and the isolation of mutants that are specifically altered in the synthesis and transport of haemolysin. These mutants were obtained by chemical mutagenesis and insertion of the ampicillin transposon (Tn3) into pHly152. Tn3 transposition was also used for the identification and the location of the cistrons on pHly152 essential for haemolysis. The EcoRI and HindIII fragments of the haemolytic plasmid pHly152 were cloned and used for the complementation of the haemolysis negative Tn3 insertion mutants. A DNA segment of 3.2 x 10(6) dalton could be thus identified which consists of at least three clustered cistrons necessary for haemolysis. Two of these cistrons are required for the formation of active haemolysin. At least one other cistron seems to be involved in the secretion of active haemolysin through the outer membrane of E. coli. The gene products determined by these cistrons were identified in minicells of E. coli. Their molecular properties were determined and their possible function in the formation and secretion of haemolysin will be discussed.

Escherichia coli↗
PubMed1987

The chromosomal fur gene regulates the extracellular haemolytic activity encoded by certain hly plasmids.

The haemolytic activity encoded by thirteen hly-plasmids of different origin and sources was examined as a function of the Fe3+-concentration in E. coli fur+ and E. coli fur- strains, respectively. In E. coli fur+ the relatively low haemolytic activity of five hly-plasmids isolated in Berne and one isolated in Paris was increased significantly under iron-limiting growth conditions. Contrastingly, in E. coli fur- strains containing the same plasmids, a considerably higher amount of secreted haemolysin was detected. This activity could not be further increased by limiting the extracellular iron concentration. Seven other hly-plasmids expressed similar and non-inducible amounts of secreted haemolysin in both E. coli fur+ and E. coli fur- strains. These results indicate that the extracellular haemolytic activity encoded by certain hly-plasmids was controlled by the chromosomally encoded fur gene.

Animals↗
PubMedDate not supplied

Salmonella typhimurium strains carrying haemolysin plasmids and cloned haemolysin genes from Escherichia coli.

Like all other Salmonella typhimurium strains examined, the smooth variants SF1397 (LT2) and 1366 and also their semi-rough and rough derivatives are non-haemolytic. Nevertheless, two haemolysin (Hly) plasmids of E. coli belonging to the inc groups incFIII,IV (pSU316) and incI2 (pHly152) were able to be introduced into these strains by conjugation and stably maintained. A considerable percentage of the Hly+ transconjugants obtained had lost parts of their O-side chains, a result of selection for the better recipient capability of "semi-rough" variants rather than the direct influence of the Hly+ plasmids themselves. In contrast to the incFIII,IV plasmid pSU316, which exhibited higher conjugation rates with rough recipients, the incI2 plasmid pHly152 was accepted best by smooth strains. Transformation with cloned E. coli haemolysin (hly) determinant was inefficient (less than 10(-6)) for smooth strains, but 10(2) - 10(3) times higher for rough recipients, and was increased by the use of Salmonella-modified DNA. The transformants and transconjugants were relatively stable and showed the same haemolytic activity as the E. coli donor strains. The virulence of the Hly+ smooth, semi-rough and rough S. typhimurium strains was tested in two mouse models, and neither the mortality rate nor the ability to multiply within the mouse spleen was influenced by the hly determinants.

Animals↗