Barrett Sugarman

Adherence of bacteria to suture materials.

Abstract Sutures were incubated in suspensions of radiolabeled Enterobacteriaceae or Staphylococcus aureus and nonadherent bacteria were removed by washing. Adherence of bacteria to gut was up to 100 times greater than to nylon; adherence to polyglycolic acid or silk was intermediate. These results correlate with laboratory and clinical investigations which have suggested that gut sutures have the highest frequency of association with surgical wound infection, followed by silk and nylon in descending order of frequency. Braided materials had increased adherence compared to nonbraided materials, probably due to increased surface area. Adherence of Enterobacteriaceae to suture material was saturable and time dependent and was blocked by addition of unlabeled bacteria. Adherence of bacteria to sutures may be an integral part of the pathogenesis of certain surgical infections.

The Effect of Hormones on Trichomonas vaginalis

The hormonal milieu can alter susceptibility to infection. The effect of hormones on Trichomonas vaginalis was studied utilizing axenically cultured clinical isolates. Oestrogens, in physiological concentrations, decreased the growth of the organisms and their attachment to mammalian cells in vitro, and acted as a chemorepellent. The specificity of these effects was verified by their being blocked with anti-oestrogens, by the dose- and time-dependency of the responses, and by the lack of effect with other hormones. These results suggest that oestrogens may decrease the virulence of T. vaginalis; however, interactions between oestrogens and mammalian cells may promote the development of infection. Thus complicated interactions between hormones, micro-organisms and mammalian cells must determine whether exposure to oestrogens predisposes to or prevents the development of infection.

Antibiotic and nonantibiotic ionophores can alter bacterial adherence to mammalian cells.

Abstract Epithelioid (HeLa) and fibroblastic (L) cells in culture incubated for 18 hr with the ionophores amphotericin B and amiloride were noted to bind significantly more and less bacteria, respectively, than control cells incubated without ionophores. These effects were related to dose and incubation length and were present at concentrations approximating those in vivo after administration of maximal doses of these drugs given to humans therapeutically. Electron microscopy of both receptor cell lines revealed increased length and number of cellular projections in the amphotericin-treated cells and flattening and loss of membrane individuality in the amiloride-treated cells. These findings could explain the differences in subsequent bacterial binding. The ionophores nifedipine and verapamil which block calcium transport in cells which have calcium channels did not alter bacterial binding to these receptor cells or bacterial binding to calcium channel-containing myoblasts (in culture). These data suggest that certain ionophores could alter bacterial colonization and infection in the host indirectly by altering bacterial binding; however, the clinical significance of these findings remains to be determined.

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

SummaryCertain nutrient chemotactic agents after 3–18 hours of incubation with viable mammalian cells in culture can cause significant alterations in subsequent attachment ofEscherichia 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. AllE. coli isolates tested readily displayed chemotaxis, yet significant differences in adherence were observed with the minority of 16 chemotactic agents, two receptor cell lines, sixE. coli and oneSalmonella 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.ZusammenfassungBestimmte chemotaktische Nährstoffe können nach Inkubation mit lebenden Mammalierzellen in Kultur über 3–18 Stunden signifikante Veränderungen im nachfolgenden Anheften vonEscherichia coli an die Mammalier (Rezeptor)-Zellen verursachen. Die Ergebnisse waren am ausgeprägtesten mit einem im wesentlichen nicht oxydierbaren Aminosäure-Analogon. Die festgestellten Unterschiede standen in Abhängigkeit von der Zahl der Waschungen der Rezeptorzellen nach Inkubation mit den chemotaktischen Substanzen und ihren Konzentrationen während der Inkubation. AlleE. coli-Isolate wiesen unmittelbar Chemotaxis auf, doch wurden signifikante Unterschiede in der Adhärenz nur mit wenigen der 16 untersuchten chemotaktischen Substanzen, zwei Rezeptorzellinien, sechsE. coli-Stämmen und einemSalmonella typhi-Stamm beobachtet. Dies beruht sehr wahrscheinlich darauf, daß diese Substanzen sich auf den äußeren Schichten von lebenden Mammalierzellen nur schwach anlagern, möglicherweise auch auf der Verstoffwechselung der Substanzen oder auf beiden Faktoren. Manche chemotaktischen Nährstoffe unterstützen möglicherweise die selektive Kontrolle der bakteriellen Kolonisation oder Infektion.