Attachment of bacteria to mammalian surfaces

Zinc-dependent cytoadherence of Legionella pneumophila to human alveolar epithelial cells in vitro

Microbial adherence to host cells is an early key step in the establishment of infection. During the course of Legionnaire's disease, Legionella interactions with host cells are best documented for resident macrophages. However, L. pneumophila can also replicate within type I and type II pneumocytes, which cover almost the entire alveolar surface. In the presence of zinc, we observed a significant and concentration-dependent increase in L. pneumophila adherence to and invasion of type II pneumocytes. The zinc-dependent adherence mechanism seemed to be host-cell-independent, as a similar increase in cytoadherence was observed with macrophages. We also found that zinc-dependent adherence of L. pneumophila appears to involve recognition of zinc-binding pneumocyte receptors by a bacterial adhesin, and heparan-sulfated host cell receptors, but not type IV pili.

Evaluation of hydrophobicity and adherence of Neisseria meningitidis strains and a study of their correlation by analysis of alterations induced by antibiotics

Surface hydrophobicity and adherence to human buccal epithelial cells were evaluated in four Neisseria meningitidis strains. Hydrophobicity was measured by partition into p-xylene in the presence or absence of ammonium sulphate, whereas radioactivity-labelled bacteria were used to estimate the ability to adhere to buccal cells by liquid scintillation techniques. Eight antibiotics were employed to induce modifications in the two parameters in order to estimate their possible relationship. The presence of ammonium sulphate enhanced the partition into p-xylene and hence the hydrophobicity values obtained. There was no correlation between adherence and hydrophobicity (no matter what the method employed to evaluate the latter). The effect of the antibiotics varied as a function of the strain, method and/or parameter tested.

Bacterial adherence to vascular grafts after in vitro bacteremia

All currently used arterial prosthetics have a greater susceptibility to infection following bacteremia than does autogenous tissue. This experiment compares quantitative bacterial adherence to various prosthetic materials after bacteremia carried out in a tightly controlled and quantitative fashion. Ten centimeters long, 4 mm i.d. Dacron, umbilical vein (HUV), and polytetrafluoroethylene (PTFE) grafts, as well as PTFE grafts with a running suture line at the midportion were tested. Each graft was interposed into a pulsatile perfusion system modified from a Waters MOX 100 TM renal transplant pump. Indium-111-labeled Staphylococcus aureus were added to heparinized canine blood to give a mean concentration of 4.7 X 10(6) bacteria/cc. This infected blood was recirculated through each graft for 30 min at a rate of 125 cc/m, 100 Torr (sys), 60 beats/min. The gamma counts/graft were used to calculate the number of bacteria/cm2 of graft surface. After nine experiments, a mean of 9.63 X 10(5) bacteria/cm2 were adherent to the Dacron, 1.04 X 10(5) bacteria/cm2 to the HUV, and 2.15 X 10(4) bacteria/cm2 to the PTFE. These differences were all significant at the 0.05 level. The addition of a suture line increased bacterial adherence to the PTFE graft by 50%. These results suggest that PTFE is the vascular graft material of choice when a prosthetic graft must be implanted despite a high risk of subsequent clinical bacteremia. Our in vitro, pulsatile perfusion model gave accurate and reproducible results, and appears well suited for further studies of bacterial, or platelet adherence to grafts, as well as the biomechanics of vascular conduits.

Nutrient chemotactic agents and the in vitro selective control of bacterial colonization

Certain nutrient chemotactic agents after 3-18 hours of incubation with viable mammalian cells in culture can cause significant alterations in subsequent attachment of Escherichia coli to the mammalian (receptor) cells. Results were amongst the most significant with an essentially non-oxidizable amino acid analogue. Differences obtained were dependent upon the number of washings of the receptor cells after incubation with the chemotactic agents and the incubation concentrations. All E. coli isolates tested readily displayed chemotaxis, yet significant differences in adherence were observed with the minority of 16 chemotactic agents, two receptor cell lines, six E. coli and one Salmonella typhi studied. This is most likely due to poor localization of these agents in the outer layers of viable mammalian receptor cells, metabolism of the agents, or both. Some nutrient chemotactic agents may facilitate the selective control of bacterial colonization or infection.

Leishmania mexicana mexicana: attachment and uptake of promastigotes to and by macrophages in vitro

Promastigotes of Leishmania mexicana mexicana attach to mouse macrophages in vitro in the absence of serum by a wheat germ agglutinin-like ligand on the surface of the promastigote that binds to the N-acetyl glucosamine moiety of a receptor on the surface of the macrophage. The binding is temperature dependent, and the macrophage receptor is trypsin, cytochalasin B, and is assisted or inhibited as for attachment. Treatment of promastigotes with proteolytic enzymes uncovers a receptor for a serum component that binds strongly to a mouse macrophage receptor in vitro. The strain of mice donating the macrophages had little effect upon attachment and uptake except that A strain mouse macrophages attached fewer promastigotes in 10 min than those of outbred mice, but took up as many promastigotes over 90 min as those of outbred mice. Low responder Biozzi mouse macrophages took up more promastigotes than high responder Biozzi mouse macrophages. Normal unheated human, rabbit, and guinea pig sera lysed promastigotes and so inhibited their attachment to macrophages in vitro. Unheated immune serum showed an enhanced inhibition of attachment. Heated normal serum allowed attachment and uptake, while promastigotes treated with heated immune serum showed enhanced attachment to and uptake by macrophages. Treatment of macrophages in vitro with immune serum enhanced their ability to attach promastigotes and to engulf them. Repeated 90-min exposures of a population of promastigotes to uptake by mouse macrophages in vitro did not deplete the population of any sub-population more likely to be taken by macrophages.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of cadmium and zinc on microbial adherence

A study has been made of the effect of cadmium chloride and zinc acetate on the adherence of Streptococcus faecalis, Escherichia coli and Candida albicans to buccal cells from man. Cadmium led to a significant decrease in the adherence of the three microorganisms tested. Zinc increased the adherence of S. faecalis and E. coli. These alterations in adherence were suppressed by chelating agents. S. faecalis grown in the presence of zinc or cadmium exhibited a decrease in adhesiveness. Pre-incubation of organisms with zinc interfered with the inhibitory effect of cadmium.

Zinc and bacterial adherence

Zinc significantly enhances the ability of piliated Gram-negative and Gram-positive bacteria to attach to HeLa cells. This effect is related to the concentration of zinc and degree of bacterial piliation, and is not present with unpiliated organisms. Bacterial viability is not necessary for this effect, and sulfhydryl blockers decrease the response. These data suggest that zinc can bind to bacterial pili and augment bacterial adherence; in this manner, zinc may act as a virulence factor.

In vitro adherence of bacteria to prosthetic vascular grafts

The adherence of staphylococci and Enterobacteriaceae radiolabelled with 3H-thymidine to Dacron and polytetrafluoroethylene prosthetic vascular graft materials was investigated using an in vitro method. Adherence readily occurred after a few minutes of incubation. Enterobacteriaceae adhered to Dacron in a 10-100 times greater number per mm of length than to polytetrafluoroethylene. The addition of velour to the Dacron graft further increased the number of adherent bacteria. In contrast, the adherence of coagulase-negative and positive staphylococci per mm of length was roughly the same to Dacron and polytetrafluoroethylene. The adherence of bacteria to vascular graft materials may be part of the underlying pathogenesis of vascular graft infections and differential adherence amongst various graft materials could be of clinical importance. However, in the absence of controlled clinical studies, the significance of these findings remains to be determined.