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P Gemski

Publications and source records attributed to P Gemski.

At least 19 recordsLinked to original sources
PubMed1992

The K1 capsule is the critical determinant in the development of Escherichia coli meningitis in the rat.

Although Escherichia coli strains possessing the K1 capsule are predominant among isolates from neonatal E. coli meningitis and most of these K1 isolates are associated with a limited number of 0 lipopolysaccharide (LPS) types, the basis of this association of K1 and certain 0 antigens with neonatal E. coli meningitis is not clear. The present study examined in experimental E. coli bacteremia and meningitis in newborn and adult rats whether or not the K1 capsule and/or O-LPS antigen are critical determinants in the development of meningitis. Rats received subcutaneously at K1 E. coli strain (018+K1+) or mutants lacking either the K1 capsule (018+K1-) or 0 side-chain (018-K1+). 12-24 h later, blood and cerebrospinal fluid (CSF) specimens were obtained for quantitative cultures. The isolation of E. coli from CSF was observed in both newborn and adult rats infected with K1+ strains regardless of LPS phenotype (018+ or 18-) who also developed a high degree of bacteremia (e.g., greater than 10(4) CFU/ml of blood). In contrast, none of the newborn and adult rats infected with 018+K1- and developing bacteremia of greater than 10(4) were found to have positive CSF cultures. These findings indicate that the presence of the K1 capsule and a high degree of bacteremia are key determinants in the development of E. coli meningitis, suggesting that there may be specific binding sites present in the brain which have an affinity for the K1 capsule and thus may be responsible for the entry of K1-encapsulated E. coli into the meninges.

Animals↗
PubMed1990

Aerobactin and alpha-hemolysin as virulence determinants in Escherichia coli isolated from human blood, urine, and stool.

Because iron acquisition is essential to the survival of invasive strains of Escherichia coli, the frequency of two potential iron acquisition systems, aerobactin and hemolysin production, were compared in E. coli isolated from human blood (n = 95), urine (n = 100), and stool (n = 50). By phenotypic and genotypic methods, the prevalence of hemolysin production was 22% in bacteremic, 38% in urinary, and 22% in fecal isolates of E. coli. Aerobactin production was detected in 76% of blood and in 73% of urinary isolates but in only 52% of fecal isolates (P less than .01). A reciprocal relationship was found in blood isolates between aerobactin and hemolysin; the majority of blood isolates (55%) that lacked aerobactin were hemolytic, whereas only 14% of blood isolates that expressed aerobactin were hemolytic (P less than .0001). Aerobactin may be the principal mechanism of iron acquisition in extraintestinal isolates of E. coli, and hemolysin may serve as an alternative mechanism in the absence of aerobactin genes.

Bacterial Proteins↗
PubMed1990

Staphylococcus aureus enterotoxin B challenge of monkeys: correlation of plasma levels of arachidonic acid cascade products with occurrence of illness.

Arachidonic acid cascade products have been shown to be increased in vitro in Staphylococcus aureus enterotoxin B (SEB)-treated epithelial cell cultures in our laboratory. In order to confirm that these products were clinically related to SEB intoxication, monkeys were administered SEB by nasogastric intubation. It caused emesis in five of six monkeys (less than 4 h), and the sixth monkey showed signs of mild illness. The monkeys which vomited continued to display signs of gastrointestinal illness beyond 8 h but were without any apparent signs of illness by 24 h. Blood samples were collected prior to SEB administration, upon first indication of illness, and at twice that time interval. One week prior to SEB treatment, the same monkeys were administered saline by nasogastric intubation and in every way handled similarly in order to serve as their own controls. Blood samples were taken from the control animals at 0, 4, and 8 h. The plasma concentrations of prostaglandin E2 (PGE2), leukotriene B4 (LTB4), and 5-hydroxyeicosatetraenoic acid (5-HETE) did not vary significantly throughout the 8-h experiment for saline-treated controls, nor did they differ from the concentrations found in the plasma of monkeys just before administration of SEB. When the SEB-treated monkeys showed the first indication of illness (less than 4 h), the mean of the concentration in plasma of PGE2 increased 1.44-fold, that of LTB4 increased 2.23-fold, and that of 5-HETE was essentially unchanged. At twice the time interval of the first display of illness (less than 8 h), PGE2 was still elevated (1.48-fold), LTB4 had decreased slightly to 1.66-fold, and 5-HETE had soared (3,45-fold), suggesting a divergence in the enzymatic utilization of the parent compound of the latter two metabolites, 5-hydroperoxyeicosatetraenoic acid. These studies suggest that arachidonic acid cascade metabolites were a consequence of SEB intoxication and may provide a logical site for metabolic interference in SEB-induced toxicity.

Animals↗
PubMed1990

Oligonucleotide probes for detection and differentiation of Staphylococcus aureus strains containing genes for enterotoxins A, B, and C and toxic shock syndrome toxin 1.

Different synthetic DNA nucleotide sequences were evaluated as gene probes for the specific detection and differentiation of Staphylococcus aureus strains encoding enterotoxins A (SEA), B (SEB), and C (SEC) and toxic shock syndrome toxin 1 (TSST-1). Identification of sequences unique to each toxin, based on knowledge of their nucleotide sequences, led to preparation of the specific 18-base oligonucleotide probes EA1 (encoding amino acids 177 to 182 of SEA), EB2 (encoding amino acids 105 to 110 of SEB), EC5 (encoding amino acids 125 to 131 of SEC1), and TS1 (encoding amino acids 160 to 166 of TSST-1). In colony blot hybridization analyses, these probes hybridized specifically with DNA from strains that produced the respective toxin serotypes. An excellent (greater than or equal to 93%) correlation between hybridization results (genotype) and toxin protein detection by an enzyme-linked immunosorbent assay (phenotype) was observed in the characterization of both reference and clinical strains of S. aureus for SEA, SEB, and TSST-1. A lower correlation (64%) for SEC reflected a lack of sensitivity in detecting toxin production. Our findings demonstrate that molecular DNA hybridization with synthetic oligonucleotide probes provides another approach for establishing the toxigenicity of S. aureus.

Amino Acid Sequence↗
PubMed1989

Pretreatment with recombinant murine tumor necrosis factor alpha/cachectin and murine interleukin 1 alpha protects mice from lethal bacterial infection.

Tumor necrosis factor/cachectin (TNF/C) is the principal mediator of bacterial endotoxin-induced shock and death. We found that the C3H/HeJ mouse, which is less able to produce TNF/C in response to endotoxin, has a 1,000-fold greater susceptibility to lethal infection with Escherichia coli than the TNF-responsive congenic mouse, C3H/HeN. This surprising finding suggested that this lethal peptide may also be involved in host protection. To test this hypothesis we pretreated the C3H/HeJ mouse with a combination of recombinant murine TNF/C-alpha and IL-1 alpha. This combination protected these mice against an intraperitoneal bacterial challenge of greater than 20 LD50S (nearly 2 x 10(2) CFU) that grew to a level of greater than 10(7) CFU/ml of blood and per gram of liver in untreated mice. This suggests a significant role for these cytokines in host defenses against invasive infections that require bacterial replication within the host. These protective mechanisms may not be important for less virulent organisms. These findings may have important implications for the proposed use of anti-TNF/C agents in the treatment of septic shock.

Animals↗
PubMed1989

Rapid purification of staphylococcal enterotoxin B by high-pressure liquid chromatography.

The Staphylococcus aureus enterotoxins represent a group of proteins that cause emesis and diarrhea in humans and other primates. We have developed a rapid two-step high-pressure liquid chromatography (HPLC) procedure for purification of staphylococcal enterotoxin B (SEB). Sterile filtrates (2.5 liters) of strain 10-275 were adsorbed directly onto a reversed-phase column (50 mm by 30 cm Delta Pak; 300 A [30 nm], 15 microns, C18). SEB was obtained by using a unique sequential gradient system. First, an aqueous ammonium acetate to acetonitrile gradient followed by an aqueous trifluoroacetic acid (TFA) wash was used to remove contaminants. A subsequent TFA to acetonitrile-TFA gradient eluted the bound SEB. Further purification was obtained by rechromatography on a cation-exchange column. From 35 to 45% of the SEB in starting filtrates was recovered. Analysis by immunoblotting of samples separated on sodium dodecyl sulfate-polyacrylamide gels indicated that HPLC-purified SEB exhibited immunological and biochemical properties similar to those of the SEB standard. Induction of an emetic response in rhesus monkeys showed that the HPLC-purified toxin also retained biological activity.

Animals↗
PubMed1988

Survey of purported virulence factors of Escherichia coli isolated from blood, urine and stool.

One hundred randomly selected urinary and blood isolates and 50 stool isolates of Escherichia coli were analyzed for phenotypic characteristics which may contribute to their virulence potential. Bacteremic isolates were more likely to have K1 capsules and express mannose-sensitive hemagglutination compared to stool isolates. Blood-stream isolates more frequently contained complete 0 side-chains in their lipopolysaccharide layer and less frequently exhibited mannose-resistant hemagglutination when compared to urinary isolates. Total plasmid content, hemolysin, total colicin and colicin V production were not significantly increased in Escherichia coli from blood or urine when compared to those recovered from stool.

Antigens, Bacterial↗
PubMed1988

Deletion of the Shiga toxin gene in a chlorate-resistant derivative of Shigella dysenteriae type 1 that retains virulence.

We used a probe specific for detecting the structural-gene sequences of Shiga toxin to analyze the genetic nature of toxin synthesis in mutant derivatives of Shigella dysenteriae type 1. A chlorate-resistant (chl) mutant (725-78) of S. dysenteriae type 1 strain 3818T, which had retained virulence but had lost production of high levels of cytotoxic activity associated with Shiga toxin synthesis, contained a complete deletion of the Shiga toxin structural-gene sequences. These structural-gene sequences were also absent in a derivative of S. dysenteriae type 1 that contained a substitution of Escherichia coli DNA in the trp region of the chromosome. Isolates of Shigella flexneri and Shigella sonnei also did not react with the probe. The low-level cytotoxic activities associated with the mutant S. dysenteriae type 1 strains or with the virulent S. flexneri and S. sonnei strains are neutralizable with antiserum to Shiga toxin; however, these cytotoxic activities are not determined by the genes encoding classic Shiga toxin.

Bacterial Toxins↗
PubMed1986

Role of lipopolysaccharide and capsule in the serum resistance of bacteremic strains of Escherichia coli.

To define the relative roles of capsule and lipopolysaccharide in the virulence of Escherichia coli obtained from blood, we compared the behavior of K1- and K5-encapsulated strains in serum bactericidal and rat virulence assays. Unencapsulated isogenic mutants selected from five parent strains of E. coli O12:K1, but not of O18:K1 or O7:K1 (all rough-specific phage insensitive), were lysed by normal human sera. In contrast, isogenic mutants from strains of serotypes O6:K5 and O18:K5 retained the serum resistance of the parent strains. There was a greater than 10(5) difference in LD50 in newborn rats between K1-positive and K1-negative pairs of E. coli serotypes O18 and O7 and a greater than 1 log difference between isogenic pairs of serotype O12; however, the K5 isogenic pairs had a similar LD50. Some non-O6 O serotypes, however, required the K5 capsule for serum resistance. We conclude that some O serotypes require encapsulation for optimal virulence but that other O serotypes may not.

Animals↗
PubMed1986

Genetic studies of kanamycin resistance in Campylobacter jejuni.

Campylobacter jejuni 3H40 and 4B20 harbored 59-kilobase (kb) self-transmissible plasmids encoding resistance to kanamycin and tetracycline. Although the two antibiotic resistances were more frequently inherited together, some transconjugants and ethidium bromide segregants which were resistant to only one of these antibiotics were recovered. The kanamycin-susceptible, tetracycline-resistant segregants carried plasmids 4 kb smaller than the 59-kb plasmids of their parents, whereas the kanamycin-resistant, tetracycline-susceptible segregants contained no detectable plasmid DNA. Restriction endonuclease maps of deleted forms of the 59-kb plasmids revealed that deletions and rearrangements of 4-kb lengths of DNA were associated with loss of kanamycin resistance. Translocation of the kanamycin resistance determinant between plasmid and chromosomal DNA was demonstrated. Such phenomena have not been previously described in C. jejuni spp. and are consistent with the interpretation that the kanamycin resistance determinant is encoded by a translocatable element.

Campylobacter fetus↗
PubMed1985

High frequency transduction by phage hybrids between coliphage phi 80 and Salmonella phage P22.

phi 80immP22dis, a hybrid between phi 80 and P22, carries all the late genes of phi 80 and most of the P22 early region including the immC and immI bipartite immunity loci. The presence of the immI region allows this hybrid to grow on lysogens of phi 80immP22 hybrids which have the immC locus, but not the immI locus. In addition to these P22 immunity regions, phi 80immP22dis contains the P22 att marker so that the prophage can be inserted into the chromosomal P22 attachment site adjacent to the proA-proB region of the host. Unlike its phi 80 parent which performs specialized transduction of the trp region, phi 80immP22dis transduces markers located adjacent to its attachment site to Escherichia coli K12 recipients at high frequencies (0.3% for argF and 0.18% for proA). Induction of phi 80immP22dis lysogens yields new hybrid phage clones which have incorporated E. coli K12 chromosomal segments in place of the P22 immI to att segment. Having lost the immI region, the new hybrids no longer grow in phi 80immP22 lysogens. These new hybrids, termed phi 80immP22dis-, possess specialized transducing properties, transferring the argF and proA markers at higher frequencies (21% for argF and 12% for proA) than previously obtained with the phi 80immP22dis phage.

Coliphages↗
PubMed1979

Shigellosis and Escherichia coli diarrhea: relative importance of invasive and toxigenic mechanisms.

Shigellae and dysentery-like Escherichia coli must invade the epithelium of the colon to cause disease which can present as dysentery, diarrhea, or both. This paper addresses the possible role of a Shigella dysenteriae-like (Shiga-like) toxin in the pathogenesis of shigellosis and E. coli diarrheal diseases. The possibility for such a role is suggested by the following observations: 1) diarrhea, considered to be a result of secretion of water by the small bowel, is frequently observed in shigellosis, a large bowel disease. 2) Even though shigellae do not invade the jejunum of monkeys fed Shigella flexneri, jejunal secretion is seen in animals with diarrhea. 3) The Shiga toxin of S. dysenteriae has enterotoxic activity and other serotypes of shigellae produce Shiga-like toxins. 4) E. coli 015 RDEC-1 causes a diarrheal disease and frequently death in young rabbits. This organism neither produces E. coli enterotoxins nor is it invasive, but it may produce low levels of a Shiga-like toxin.

Animals↗
PubMed1978

lambdaimm P22dis: a hybrid of coliphage lambda with both immunity regions of Salmonella phage P22.

Genetically marked lambda and P22 phages were recombined in Escherichia coli-Salmonella typhimurium hybrid WR4028, a host sensitive to infection by both of these phages. Hybrid phages that acquired the immC region of P22, but retained the genes for the lambda protein coat were selected on WR4027 (lambda), a lambda-immune, P22-resistant derivative of WR4028. In these lambdaimmP22 hybrids, at least the c through P genes of lambda were replaced with functionally related P22 genes. Phage recombinants with more extensive regions of the P22 genome were selected on the double lysogen WR4027 (lambda, lambdaimmP22). One such hybrid, lambdaimmP22dis, was determined by heteroduplex analysis to contain approximately 40% of the P22 genome. Genetic studies established that lambdaimmP22dis possesses the two widely separated immunity control regions of P22 (immC and immI) and that these loci are expressed in E. coli K-12 lysogenic for lambdaimmP22dis. In addition, lambdaimmP22dis contains the P22 a 1 locus responsible for somatic 0--1 antigen conversion in Salmonella. Although the lambdaimmP22dis phage particle has the lambda head and tail, the phage genome also carried P22 tail gene 9 as evidenced by the production of free P22 tails. It also has the P22 att site as indicated by the integration of the lambdaimmP22dis prophage near the proA locus on the bacterial chromosome.

Antigens, Bacterial↗
PubMed1978

Cellular release of heat-labile enterotoxin of Escherichia coli by bacteriophage induction.

Treatment of some enterotoxigenic Escherichia coli strains with the antibiotic mitomycin C resulted in lysis of the bacteria. Heat-labile enterotoxin (LT) activity of culture filtrates, determined by means of the Y-1 adrenal cell assay, increased dramatically as lysis of the culture proceeded. Further studies with E. coli strains 263 and B21-4 revealed that lysis is due to mitomycin C induction of vetetative development of a temperature bacteriophage. These findings suggest that the elevated levels of LT detected after mitomycin C treatment reflect the lytic release of cell-bound LT rather than the induction by mitomycin C of de novo toxin biosynthesis. Comparable increases in LT activity also resulted from thermal induction of a phage P1Cm lysogen of strain 263 or from sonic disruption of enterotoxigenic strains.

Bacterial Toxins↗
PubMed1978

Interaction between bacteriophage Sf6 and Shigella flexner.

The Shigella flexneri phage Sf6 has an isometric head with hexagonal symmetry 53nm in diameter. The noncontractile tails in 16 nm long and terminates with a base plate containing six spikes. Sf6 is typical of the C phages in the morphological classification of Bradley. Phage Sf6 processes alpha-1,3-endorhamnosidase activity as demonstrated by methylation and reducing end group sugar analyses of the products obtained on interaction with the O-polysaccharide chain of S.flexneri strains which have the O-group 3,4 antigen. The major end product was an octasaccharide with the following structure: Rha III-GlcNAc-Rha I-Rha II-Rha III-GlcNAc-Rha I-Rha II. Acetylation of 0-2 of rhamnose III of the O-polysaccharide chain, either brought about by Sf6 lysogenization or found in wild-type S. flexneri (3b) strains, prevented enzymatic hydrolysis. O-deacetylation of the polysaccharide chain again made it susceptible to the S6f endorhamnosidase.

Antigens, Bacterial↗