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Biomedical subjects

C Pruzzo

Publications and source records attributed to C Pruzzo.

At least 37 records · Page 2Linked to original sources
PubMed1991

Serum dependent expression of Enterococcus faecalis adhesins involved in the colonization of heart cells.

Our previous studies have shown that the adhesive ability of Enterococcus faecalis is dependent on the strain and is further modified by growth in serum. The data reported here demonstrate that E. faecalis adherence is mediated by carbohydrate residues present on the bacterial cell surface. Some of these (D-mannose and D-glucose) are expressed by strains isolated from both urinary tract infections (UTI) and endocarditis (EN) when the cells are grown in brain-heart infusion broth (BHIB), and mediate adherence to either urinary tract epithelial cells or the Girardi Heart (GH) cell line. Other residues are present only on EN strains (D-galactose and L-fucose) and mainly mediate adherence to GH cells. These ligands can also be expressed by UTI isolates after growth in serum. D-galactose-bearing adhesins also seem to be involved in internalization of serum grown UTI strains and BHIB or serum grown EN isolates into GH cells.

Bacterial Adhesion↗
PubMed1990

Role of neuraminidase-dependent adherence in Bacteroides fragilis attachment to human epithelial cells.

Of 50 B. fragilis strains isolated from clinical samples we have demonstrated that 24 (48%) possess an adhesin that mediates a neuraminidase-dependent attachment of B. fragilis to mammalian epithelial cells, but does not mediate any association with human polymorphonuclear leucocytes. This ligand interacts with a mammalian cell receptor that contains a galactoside residue, exposed after neuraminidase pretreatment. Our results suggest a possible role for cell associated neuraminidase in mediating a two step adherence mechanism.

Adhesins, Bacterial↗
PubMed1989

Incidence of hemagglutination activity among pathogenic and non-pathogenic Bacteroides fragilis strains and role of capsule and pili in HA and adherence.

We analyzed the ability of 120 encapsulated strains of B. fragilis to agglutinate guinea pig and human red blood cells. Sixteen strains showed a strong hemagglutination (HA) ability, 21 strains a moderate HA ability, 7 strains a weak HA ability and 74 strains did not agglutinate the tested red blood cells. Six strains tested from each HA group were able to adhere to cheek epithelial cells and to a cultured human intestinal cell line. Hemagglutinating strains were the most adhesive. By electron microscopy, pilus-like structures were found in three of the encapsulated adhesive strains. Treatment of the bacterial cells with pronase E reduced both HA ability and adherence of piliated encapsulated, and of piliated non-encapsulated strains. Glucosidase treatment of cells reduced HA activity and adherence of piliated encapsulated and of non-piliated encapsulated strains. Finally, it was found that hemagglutinating strains are more frequently isolated from clinical specimens (55%) than from feces of healthy donors (20%).

Bacterial Adhesion↗
PubMed1989

Impairment of phagocytosis by the Klebsiella pneumoniae mannose-inhibitable adhesin-T7 receptor.

It has been previously shown that Klebsiella pneumoniae K59 carrying the mannose-inhibitable adhesin-T7 receptor (MIAT) efficiently binds to polymorphonuclear leukocytes (PMNs) incubated at 4 degrees C but is not efficiently bound and internalized by phagocytes incubated at 37 degrees C. Pretreatment of K59 with compounds that bind the MIAT ligand (D-mannose, UV-inactivated T7 phages, and pepsin-digested anti-MIAT antibodies) enables PMNs to phagocytize and kill these bacteria. In this article, we show that the incubation temperature has no direct effect on expression of either the MIAT or the PMN receptors. These receptors were always expressed at 37 degrees C when PMNs were treated with substances that impaired their ability to rearrange their surfaces (glutaraldehyde and cytochalasins B and D). Pretreatment of inert PMNs with concanavalin A or succinyl concanavalin A drastically reduced binding of K59 to phagocytes at both 4 and 37 degrees C. The same pretreatment carried out with metabolically active PMNs enabled them to efficiently phagocytize the MIAT-positive strain. When phagocytes were treated with K59 bacteria, they became unable to ingest and kill a K59 mutant not expressing the MIAT which was sensitive to phagocytosis. If this pretreatment was performed in the presence of D-mannose, UV-inactivated T7 phages, and pepsin-digested anti-MIAT antibodies, PMNs maintained their phagocytic activity against the MIAT-negative strain. In the presence of K59 bacteria, a very low chemiluminescence response was generated; in contrast, a significant response was observed when bacteria were previously absorbed with UV-inactivated T7 phages and pepsin-digested anti-MIAT antibodies. These results support our previous suggestion that the MIAT adhesin triggers changes in the cell surface, inhibiting further binding and phagocytosis.

Bacterial Adhesion↗
PubMed1989

Role of adherence in pathogenesis of Enterococcus faecalis urinary tract infection and endocarditis.

Enterococcus faecalis strains isolated from urinary tract infections (UTIs) and endocarditis were analyzed for their ability to adhere to urinary tract epithelial cells (ECs) and Girardi heart (GH) and human embryonic kidney (HEK) cell cultures. UTI isolates adhered to urinary tract ECs more efficiently than to the cultured cells, at the same time showing the least affinity for GH cells. In contrast, endocarditis isolates adhered to GH cell cultures more readily than to urinary tract ECs. Moreover, although strains isolated from endocarditis adhered to GH cells more efficiently than those derived from UTI, the latter strains adhered to urinary tract cells better than the former. Studies of the ability of GH and HEK cells to internalize E. faecalis showed that for UTI isolates, 9 to 74% of adhered bacteria were internalized, while for endocarditis isolates, the percentage varied from 76 to 82%. All strains were able to associate with human neutrophils; endocarditis strains, however, associated less efficiently than UTI isolates. Growth in serum raised the adherence of all tested strains by at least 1.5- to 3-fold, with the greatest increase being observed in UTI strain adherence to GH cells (8-fold). In contrast, the association of serum-grown cells with polymorphonuclear leukocytes was reduced by two- to fivefold. In both cases, the observed serum-dependent alterations were cancelled by a few subcultures in brain heart infusion broth. These results indicate that adhesive properties are important virulence factors in the pathogenesis of UTI and endocarditis and also suggest that UTI strains showing the highest invasion and adhesive potential invade the kidneys, cause bacteremia, and, after having expressed the serum-dependent surface modification, colonize the heart.

Adult↗
PubMed1986

[Bacterial adhesins in the prophylaxis and therapy of infections].

Pathogenic bacteria must stably colonize mucosal surface to initiate the infectious process. A growing body of evidence indicates that bacteria attach to tissue surface by specific interactions between molecules of recognition (receptors) on host cell surface and adhesive molecules (adhesins) on the surfaces of the bacteria. One of the goals in the studies of bacterial adherence mechanisms is the eventual development of measures to prevent the adhesion of harmful bacteria to mucosal surfaces before the microorganism can produce tissue damage. In this paper we describe recent studies on the possibility to use in therapy either purified adhesins or receptors to block receptors and ligands respectively. We also describe recent studies on the development of antiadhesive vaccines, composed of purified ligands, to elicit local immune responses, resulting in the secretion of antibodies that cover the bacterial adhesins and thereby prevent attachment.

Anti-Bacterial Agents↗
PubMed1984

Piliated Bacteroides fragilis strains adhere to epithelial cells and are more sensitive to phagocytosis by human neutrophils than nonpiliated strains.

Fifteen unencapsulated B. fragilis strains isolated from human infections were examined for their capability to hemagglutinate erythrocytes of different species. Seven strains were found to hemagglutinate guinea pig and human (A,B,O) erythrocytes. This hemagglutination was resistant to treatment with D-mannose and several other sugars. Hemagglutinating strains were also capable of adhering to human epithelial cells and cultured human cell line (Intestine 407) and were 6- to 20-fold more adhesive than non-hemagglutinating strains. Pilus-like structures were found in negative-stained preparations on the hemagglutinating (and adhesive) strains but not on the others. Hemagglutinating and adhesive bacteria were 3- to 7-fold more sensitive to phagocytosis and 5- to 10-fold more sensitive to killing by human neutrophils than non-hemagglutinating ones.

Animals↗
PubMed1984

Positive selection of colicin cured cells by mitomycin C in Klebsiella pneumoniae.

A colicinogenic strain of Klebsiella pneumoniae (MirM7cx) was treated with chemical and physical agents in an attempt to cure it from colicin. Mitomycin C was the only agent able to eliminate the extrachromosomal element from the strain. A simple method to isolate colicin cured cells of K. pneumoniae is described.

Bacteriocin Plasmids↗
PubMed1983

Laboratory and wild-type Klebsiella pneumoniae strains carrying mannose-inhibitable adhesins and receptors for coliphages T3 and T7 are more pathogenic for mice than are strains without such receptors.

We have shown previously that Klebsiella pneumoniae receptors for coliphages T3 and T7 also mediate mannose-inhibitable adherence to human epithelial cells and protect bacteria from phagocytosis and intracellular killing by human polymorphonuclear cells. In this paper we analyze the possible role of such mannose-inhibitable adhesins and T3-T7 receptors (MIAT) in K. pneumoniae intraperitoneal pathogenicity for mice. We showed that intraperitoneal pathogenicity for mice of four different Klebsiella strains (one laboratory and three wild-type) that carry the MIAT was approximately 60-fold higher than that of four derivative strains that lost such receptors by spontaneous mutation. The MIAT could be repressed by Klebsiella phage AP3 lysogenic conversion. Two laboratory and two wild-type strains converted by phage AP3 were also approximately 60-fold less pathogenic for mice than parental strains and showed a pathogenicity level equal to that of the MIAT-negative mutants. Studies of protection in mice with anti-whole cell antisera showed that passive immunization against MIAT-positive cells was more protective than immunization against MIAT-negative cells. Studies of protection in mice by both active and passive immunization with lipopolysaccharide and purified outer membrane proteins have shown that the proteins are the most protective outer membrane components. Since it has been shown previously that the Klebsiella receptors for T3-T7 have a proteic component and that an outer membrane protein is missing in the strains resistant to T3-T7 (C. Pruzzo et al., in R. C. Berkely (ed.), Microbial Adhesion to Surfaces, 1980); the latter finding further supports the role of MIAT in the pathogenicity of Klebsiella for mice.

Adhesiveness↗
PubMed1982

Mannose-inhibitable adhesins and T3-T7 receptors of Klebsiella pneumoniae inhibit phagocytosis and intracellular killing by human polymorphonuclear leukocytes.

It has recently been shown that Klebsiella pneumoniae strains adhere to human epithelial cells and that adherence is mediated by mannose-inhibitable adhesins which are also receptors for coliphages T3 and T7. We have now found that Klebsiella strain K59, which adheres to human epithelial cells and carries the receptors for coliphages T3 and T7, adheres to human polymorphonuclear leukocytes (PMN) at 4 degrees C. Strains KRTT1 and KRTT2, which are spontaneous mutants unable to adsorb coliphages T3 and T7 and adhere to human epithelial cells, at this temperature did not adhere to PMN. Adherence of K59 cells to PMN at 4 degrees C was inhibited by D-mannose, by UV-inactivated T7 phages, and by pepsin-digested anti-K59 antibodies absorbed with KRTT1 cells. At 37 degrees C the number of PMN with KRTT bacteria associated was fourfold higher than at 4 degrees C. On the contrary, the number of PMN with K59 bacteria associated at this temperature was fourfold lower than at 4 degrees C. Phagocytosis and intracellular killing experiments performed at 37 degrees C showed that KRTT1 and KRTT2 were phagocytized and killed at a higher rate than K59. After blocking of the mannose-inhibitable adhesins and T3-T7 receptors (MIAT) by D-mannose, UV-inactivated bacteriophage T7, or specific antibodies, K59 cells became more sensitive to phagocytosis and intracellular killing at 37 degrees C. K59 cells lysogenic for prophage AP3 were approximately as sensitive to phagocytosis and intracellular killing by human PMN as strains KRTT1 and KRTT2. Unencapsulated Klebsiella strains isolated from clinical specimens were found to carry MIAT most often. Four such strains were found much more resistant to phagocytosis and intracellular killing than their spontaneous mutants resistant to bacteriophages T3 and T7.

Bacterial Proteins↗
PubMed1980

Identification of the major adherence ligand of Klebsiella pneumoniae in the receptor for coliphage T7 and alteration of Klebsiella adherence properties by lysogenic conversion.

We have studied the adherence of both laboratory and wild-type Klebsiella pneumoniae strains, isolated from sputum, urine, and stool samples, to human buccal and intestinal and urinary tract epithelial cells. Of 32 unencapsulated strains, 30 adhered to all epithelial cells tested. Four K. pneumoniae strains lysogenic for AP3, a phage which causes conversion to resistance of coliphages T3, T7, and phi I, were all unable to adhere to epithelial cells. One of these strains was cured from phage infection and became capable of adhering, Spontaneous mutants resistant to coliphage T7, as well as K. pneumoniae K59-sensitive cells preadsorbed with inactivated T7 particles, did not adhere to epithelial cells. All strains capable of adhering were able to adsorb coliphage T7 and T3, whereas all nonadhesive strains were not. AP3-like prophages were induced from 7 of 12 nonadhesive Klebsiella strains. A laboratory strain which was able to adhere was lysogenized with 2 of these phages. In both cases, the strain lost its ability to adsorb coliphages T3, T7, and phi I and to adhere to human epithelial cells. All K. pneumoniae adhesive strains agglutinated yeast cells, whereas the nonadhesive strains did not. Competition studies have shown that D-mannose and concanavalin A prevented adherence to human epithelial cells, yeast agglutination, and adsorption of coliphage T7 to K. pneumoniae cells. It is concluded that in K. pneumoniae adherence to epithelial cells is mediated by the receptor for coliphages T7 (and T3), which in turn recognizes D-mannose in the receptors it binds.

Cell Adhesion↗
PubMed1978

Close association between shape alteration and loss of immunity to superinfection in a wild-type Klebsiella pneumoniae stable lysogen which can be both immune and nonimmune to superinfection.

Klebsiella pneumoniae MirM7 is a wild-type strain which grows as cocci at pH 7 and above and as rods at pH 6.5 and below. Cultures of this strain and an auxotrophic derivative, MirM7b, have been found to undergo spontaneous lysis after purification from possible contaminating viruses. Lysates always contained two phages, FR2 and AP3, most often at high titers. FR2 and AP3 plated with the same efficiency on both MirM7b and K59 (another K. pneumoniae strain sensitive to FR2 and AP3) and lysogenized 45 and 54% of the K59-infected cells, respectively. These findings raise the possibility that MirM7b is lysogenic for FR2 and AP3, although nonimmune to their superinfection. The fact that mitomycin C and N-methyl-N'-nitro-N-nitrosoguanidine can induce phages FR2 and AP3 from MirM7b confirmed this possibility. When MirM7b was infected with FR2 several strains immune to FR2 and AP3, which were all rod shaped, were obtained. Furthermore, 19 derivatives, rod shaped at all pH's have been isolated from MirM7b. They were all immune to both FR2 and AP3. From mating experiments between the MirM7b donor derivative, strain M720, and either K59 or MirCV5, a rod-shaped MirM7b derivative cured from the prophages, cysteine recombinants were obtained which were most often (80%) immune to FR2 and AP3. Nonimmune and still lysogenic recombinants were obtained by mating M720 with a rod-shaped immune MirM7b derivative; the majority of the non-immune strains maintained the rod shape. Five coccus-shaped recombinants were also isolated; they were nonimmune to superinfection. Several physiological properties of strain MirM7b and the other nonimmune coccal recombinants have been studied in comparison with those of the rod-shaped immune derivatives. All of the coccal strains have shown several alterations with respect to the rods. The role of possible derepressed prophage genes in the various physiological alterations of MirM7 is discussed, and the analogies between this system and those of vertebrate cells transformed by proviruses are stressed.

Bacteriophages↗
PubMed1978

Lysogenic conversion in Klebsiella pneumoniae: system which requires active immunity regulation for expression of the conversion phenomenon.

We have previously described Klebsiella pneumoniae MirM7b, which, although stably lysogenic for the inducible and nondefective phages FR2 and AP3, is not immune to superinfection by these same viruses. MirA12b, a strain which is lysogenic for FR2 and AP3 and immune to superinfection, has been derived from MirM7b. The sensitivity of this strain and that of the nonimmune parent to several bacteriophages have been compared in this work. It has been found that, whereas MirM7b is sensitive to coliphages P1, T3, T7, and phiI, MirA12b is fully resistant to all of them. It is shown that phages FR2 and AP3 convert Klebsiella strains to resistance to coliphage P1 and coliphages T3, T7, and phiI, respectively, and cause loss of surface antigens in lysogenic cells. To determine such a conversion, both FR2 and AP3 require expression of immunity to superinfection. This explains the differences that exist between MirM7b and MirA12b in both phage sensitivity and surface antigens. Hypotheses are presented to explain the peculiar need for an active superinfection repressor to express lysogenic conversion.

Antigens, Bacterial↗
PubMed1978

The peculiar behaviour of coliphage P1vir mutants on restricting hosts.

The sensitivity of two vir coliphage P1 mutants, to the host-specificity systems A, K, RII, and B of Escherichia coli, and to the newly identified host-specificity systems Mir and 59 of Klebsiella pneumoniae has been studied. Both 1 vir phages were completely resistant to the E. coli K, but were restricted 10(-5) by the B, mir and 59 systems. The P1 parent, on the contrary, was restricted 10(-2) by all of the above mentioned hosts. The possible role of phage coded proteins in the altered sensitivity of the vir strains has been studied by analysing the sensitivity of both P1, and P1vir to the various systems in the presence of chloramphenicol. Protein synthesis inhibition by chloramphenicol did not significantly influence the sensitivity of P1 and P1vir to various restricting hosts. It is concluded that the altered sensitivity of vir mutants depends on the different affinities of the mutated phage DNA sequence for the enzymes of the various restriction and modification systems. The possibility that the phage repressor contributes to the regulation of the restriction and modification enzymes is also discussed.

Chloramphenicol↗
PubMedDate not supplied

Bacterial killing by Mytilus hemocyte monolayers as a model for investigating the signaling pathways involved in mussel immune defence.

The signaling pathways involved in mussel immune defence were investigated utilizing a model of killing of Escherichia coli by Mytilus galloprovincialis hemocytes in a co-culture setting. In particular, the role played by different mitogen activated protein kinases (MAPKs) and by the production of eicosanoids were investigated utilising specific cell permeant, pharmacological enzyme inhibitors. Hemocyte pretreatment with the p38 MAPK inhibitor SB203580 significantly reduced bacterial killing, whereas PD98059 (an inhibitor of ERK--extracellularly regulated kinase--MAPK activation) had no significant effect. Wortmannin also inhibited bacterial killing, indicating a crucial role for PI3-kinase activation in the immune response. Killing of E. coli was also reduced by inhibitors of both PLA2 and cyclooxygenase activities, indicating that eicosanoid production is involved in mediating the response to bacterial challenge. The results demonstrate that bacterial killing by mussel hemocytes is particularly sensitive to inhibitors of the key steps involved in the transduction of bacterial signals into the host cell. Moreover, these data indicate that the hemocyte bactericidal activity can be suitably utilized not only for identifying the signaling pathways involved in the response to bacterial infection, but also as a potential investigative-toxicology model to test drugs and contaminants for their effect on the overall mussel immune defence.

Animals↗