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C Pruzzo

Publications and source records attributed to C Pruzzo.

14 recordsLinked to original sources
PubMed1992

Novel immunoenzymatic assay for identification of coagulase- and protein A-negative Staphylococcus aureus strains.

A purified monoclonal antibody (MAb) which specifically reacts with Staphylococcus aureus glucosaminidase was obtained. This MAb was utilized to develop an immunoenzymatic assay for the identification of S. aureus strains. The sensitivity of this assay, based on the simultaneous detection of S. aureus glucosaminidase and protein A, was evaluated by analyzing a total of 196 strains, 26 of which did not exhibit one or more of the following properties: protein A, clumping factor, and staphylocoagulase. All strains yielded positive results by the MAb-based immunoenzymatic test. The assay's ability to differentiate between S. aureus and other staphylococci was then analyzed by testing a total of 277 non-S. aureus strains that yielded negative results. Our data demonstrate that this immunoenzymatic assay can be used as a single S. aureus identification criterion, particularly useful for those strains negative for clumping factor, staphylocoagulase, or protein A.

Animals↗
PubMed1991

Enterococcus faecalis: specific and non-specific interactions with human polymorphonuclear leukocytes.

In previous studies we have demonstrated that the ability of Enterococcus faecalis to adhere to and to be internalized in human urinary tract epithelial cells, Girardi Heart cells and human polymorphonuclear leukocytes (PMNs), was dependent on whether the strain had been isolated from urinary tract infections (UTI) or endocarditis (EN) respectively. These properties were further modified by growth of the organism in human serum. In the present report, using competition assays we show that adhesins containing a D-glucose moiety play a role in mediating the interactions between human PMNs and E. faecalis strains isolated from UTI and grown in brain-heart infusion broth (BHIB). On the other hand, adhesins containing both D-glucose and D-galactose moieties were involved in the interactions between PMNs and serum grown UTI isolates or EN isolates grown in either BHIB or human serum. Moreover, the impairment in the association between both UTI and EN strains after growth in serum appears to be at least partially related to a decrease in enterococcal surface hydrophobicity.

Adult↗
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↗
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↗