Initial Bacterial Colonization Research Articles

Role of Nutrients and Bacterial Colonization in the Development of Intestinal Host Defense

In this introduction to the supplement on the use of pre- and probiotics in the health and disease of pediatric patients, I have summarized factors affecting the initial colonization of the neonatal intestine. The term bacterial-epithelial cross-talk was defined, and examples of the enterocyte response to both pathologic and indigenous flora stimulation illustrated. Immaturities in the human neonatal intestinal response to bacteria and their toxins were reviewed in the context of the pathogenesis of age-specific, bacterial gastrointestinal infectious diseases. Finally, the importance of pre- and probiotics as measures to strengthen the neonate's intestinal host defenses in the prevention and treatment of specific age-related disease were considered.

Efficacy and Function of Rifampin-impregnated Silicone Catheters in the Prevention and Treatment of Foreign Body-associated CNS Infections

Objective: Infection continues to be one of the major complications of cerebro-spinal fluid shunting procedures. In most patients, the only successful therapy is explantation of the shunt device, temporary external ventricular CSF drainage, and implantation of a new system. The key to an effective infection prophylaxis seems to be the prevention of initial bacterial adhesion and/or colonization of the foreign body surface, leading to the concept of antimicrobial device impregnation. Methods: In a self-developed rodent CSF infection model, a newly designed rifampin impregnated silicone catheter was tested in 55 New Zealand White Rabbits in a prospective, randomized, controlled single-blind study. Staphylococcus epidermidis (10e8 CFU/ml) as well as Staphylococcus aureus 5aW (10e4 CFU/ml) served as test strains. Control group animals received either nontreated catheters or saline injections. Results were documented by Scanning electron microscopy (SEM) as well as bacteriological, histological, clinical and laboratory findings. Results: A colonization of the catheter surfaces...

Preparation and characterization of an Actinomyces naeslundii aggregation factor that mediates coaggregation with Porphyromonas gingivalis.

Intergeneric coaggregation is responsible for the complexity of the microbiota in human dental plaque and is believed to be important in the initial bacterial colonization of the human oral cavity. Actinomyces naeslundii, an early colonizer of the tooth surface, may enhance subsequent colonization by Porphyromonas gingivalis which is associated with adult periodontitis. The purpose of this study was to isolate and characterize the A. naeslundii aggregation factor (AnAF) that mediates coaggregation with P. gingivalis. AnAF was isolated from A. naeslundii sonic extract (SE) by gel filtration on a Sephacryl S-400HR, by hydrophobic interaction chromatography on a HiTrap Octyl Sepharose 4FF, and by ion exchange chromatography on a HiTrap Q. The specific activity increased 12-fold with a yield of 2.5%. SDS-PAGE analysis of AnAF revealed a protein band of high molecular weight in excess of 200 kDa. Carbohydrate was detected as the only material coinciding with the protein band, indicating that the AnAF was a glycoprotein. Immunoblotting analysis indicated that AnAF directly bound to P. gingivalis cells. AnAF was sensitive to sodium metaperiodate treatment but not to heat or protease treatments. These results suggest that the AnAF carbohydrate component mediated coaggregation with P. gingivalis cells. AnAF also inhibited coaggregation with other periodontal disease-associated bacteria such as Prevotella intermedia, Fusobacterium nucleatum, Capnocytophaga ochracea, but not streptococci.

Localization of the in vivoexpression of P and F1 fimbriae in chickens experimentally inoculated with pathogenic Escherichia coli

Escherichia colicausing septicemia in poultry often possess F1 (type 1) and/or P fimbriae which may be involved in bacterial colonization and infection. To investigate the expression of these fimbriae in vivo, two pathogenic E. colistrains with different fimbrial profiles, TK3 ( fim + / pap + ) and MT78 ( fim + / pap − ), were administered to 2-week-old chickens by either the intratracheal or caudal thoracic air sac inoculation route. Antibodies specific for native F1 fimbriae were detected by ELISA and immunodot in the serum of chickens inoculated with either strain MT78 or strain TK3, irrespective of the route of inoculation. Antibodies specific for P fimbriae of serotype F11 were detected by ELISA and immunoblotting in the serum of chickens inoculated by either route with strain TK3. F1, but not P fimbriae, were expressed by bacteria colonizing the trachea of chickens inoculated by the air sac route with strain MT78 or TK3, as demonstrated by examination of frozen tissue sections using immunofluorescence. F1 fimbriae were also expressed by bacteria colonizing the air sacs and lungs, but not by bacteria in the blood or other internal organs, of chickens inoculated with either strain. P fimbriae were expressed by bacteria colonizing the air sacs, lungs, kidney, blood, and pericardial fluid, but not by bacteria colonizing the trachea, of chickens inoculated with strain TK3. Fimbriae-like structures were observed by electron microscopy on bacteria adhering to the epithelial cells of the air sacs of chickens inoculated with strain TK3. These results demonstrate that both strains MT78 and TK3 undergo in vivophase variation with respect to their fimbrial profiles and site of bacterial colonization in different organs of infected chickens and suggest that F1 fimbriae are important for initial bacterial colonization of the upper respiratory tract whereas P fimbriae are important for later stages of the infection.

Influence of surface properties on accumulation of conditioning films and marine bacteria on substrata exposed to oligotrophic waters

The influence of interfacial wettabilities on initial conditioning and bacterial colonization of polished surfaces was examined in the oligotrophic, subtropical waters off O'ahu's south shore and in the laboratory. After exposures to seawater for 3 d, accumulations of attached bacteria on 11 types of substrata during two deployments varied as a second order function of substratum wettability. As observed in previous biomedical and mesotrophic field studies, surfaces with intermediate critical surface tensions (γcrit = 20–30 mN m‐1) and extremes in the polar and dispersive components of the composite surface free energy were least colonized by bacteria. Conditioning film thicknesses, varied by a factor of 100 among materials and also appeared to be a second order function of γcrit. Sorbed films produced interfaces with a range of wettabilities, dependent upon substratum and sorbate properties. Bacteria isolated from surfaces exhibited four basic partitioning patterns into non‐aqueous solvents which demonstrates that cell surface wettabilities vary widely among isolates and are characterized as (i) broadly hydrophobic, (ii) broadly hydrophilic, (iii) only compatible in phases with surface tensions < 20 mN m‐1, or (iv) only compatible in phases with surface tension > 27 mN m‐1. Partitioning patterns of cultured isolates are consistent with field observations of denser colonization of low and high γcrit surfaces. The results support the hypothesis that substratum surface properties influence conditioning film attributes and continue to exert control over bacterial adsorption and attachment even after conditioning films are established.

Salivary factors in caries models.

Consideration of salivary factors in caries models rarely extends beyond viewing saliva as a sink or diluent for plaque metabolic products, or as a source of buffering, for neutralizing plaque acids. In reality, saliva has a complex chemistry and a wide range of biochemical activities that may significantly affect plaque chemistry and microbiology. Thus, saliva is a major source of microbial nutrients, without which bacterial acid production is diminished. Buffering by salivary bicarbonate, and base production from urea and basic amino acids and peptides, significantly affect Stephan curves. Saliva is supersaturated with respect to basic calcium phosphate salts and contains novel inhibitors of calcium phosphate precipitation, while specific salivary proteins bind calcium. It seems important to consider if this system is reflected in plaque. Saliva, with contributions from serum and bacterial constituents, provides most of the precursors for the acquired enamel pellicle, which acts to slow demineralization during caries attack. Pellicle constituents appear to influence initial bacterial colonization of tooth surfaces and, therefore, may affect the microbial composition of plaque, but their detailed effects on plaque are poorly understood. Microbial adaptations to the anti-bacterial systems also seem important but are poorly investigated. Thus, saliva possesses an array of activities that have substantial actual or potential impact on plaque and, therefore, merit consideration for inclusion in systems intended to model dental caries.

Effect of SnF2 Mouthrinse on Initial Bacterial Colonization of Tooth Enamel

Microbiologic quantitative methods and scanning electron microscopy were used to observe the effect of stannous fluoride (100 ppm F-) mouthrinse on early plaque formation. An in vivo plaque model system was used on two individuals to test this experimental agent. Following SnF2 mouthrinsing, the total bacterial counts of two-day-old plaque on enamel cylinders were reduced up to 50.8 times or 98% and the streptococcal counts were decreased up to 48.4 times or 97.9%. Scanning electron microscopy confirmed a marked decrease of bacteria on enamel with use of SnF2 mouthrinse. It appears that, in addition to reducing enamel solubility and other properties, SnF2 may also alter bacterial accumulations on teeth.

Evidence for microfloral succession on allochthonous plant litter in Apalachicola Bay, Florida, USA

Changes in hydrolytic, respiratory,catabolic and lipid biosynthetic activities depend at least in part on successional changes in the microfloral populations of allochthonous plant litter incubated in a semi-tropical estuary. Initial colonization is by populations which have a high content of muramic acid relative to the adenosine triphosphate (ATP) and which are progressively displaced by a microflora with a lower ratio of muramic acid to ATP. Scanning electron micrography of the plant-litter microflora shows a succession of forms, with an initial bacterial colonization and its progressive displacement by more complex forms. Estimates of the microbial mass and the rates of phospholipid synthesis suggest that the detrital microflora has a relatively slow growth rate compared to its growth potential.