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In contrast to many commensal bacteria, uropathogens are equipped with many virulence-associated factors that facilitate infection of different areas of the urinary tract. Different extra- and intracellular bacterial lifestyles result in acute or recurrent urinary tract infection. Adhesins promote adhesion or invasion as well as biofilm formation. Flagella do not only allow ascension from the urethra to the bladder and even further to the kidneys, but can also function as adhesins and invasins. In later stages of an infection, toxins may destroy host cells, thus protecting against the host response or releasing nutrients. Extracellular polysaccharides, capsules, and the O-antigen protect bacteria against the host immune system. Furthermore, uropathogens may also directly inhibit the mucosal inflammatory response. Specific metabolic traits promote fitness, growth and survival in the urinary tract.

Introduction: Gastrointestinal infections are a significant cause of diarrhea and a worldwide problem with annually one billion illnesses and 3 to 4 million deaths. Gram negative bacteria like Enteropathogenic E. coli (EPEC) in developing countries and Enterohemorrhagic E. coli (EHEC) in the developed world are responsible for the majority of acute diarrheal episodes, especially among children less than three years of age. Pathogenic E. coli are supplied with an arsenal of effector proteins to modify and neutralize specific cellular functions of the host organism., Methods: Based on personal and extensively published results we provide a selected overview of Gram negative virulence functions with a focus on lymphostatin., Results: Lymphostatin is an effector protein encoded by lifA/efa-1 (lymphocyte inhibitory factor A/ EHEC factor for adherence). lifA/efa-1 and homologous genes have been identified in EPEC, EHEC, and mouse pathogen Citrobacter rodentium, as well as various Chlamydia strains. Multiple groups have shown that in various EHEC strains lifA/efa-1 is part of a larger pathogenicity island responsible for increased virulence. Statistically, DNA Microarray analysis associated lifA/efa-1 as the single most imortant gene with diarrhea caused by EPEC. Interestingly, lifA/efa-1 encodes for two critical enzymatic activities that have been identified in other pathogenic bacteria: glucosyltransferase- in Clostridium- and protease activity in Yersinia strains. In vitro studies identified lymphostatin as an effector protein with an immunosuppressive effect on peripheral blood and gastrointestinal mucosa T lymphocytes. Further, lymphostatin regulates the barrier function of epithelial monolayer cultures: activation of small GTPase RhoA and inhibition of Cdc42 lead to disassembly of adherens junctions and tight junctions, respectively. Besides an effect on immune and epithelial barrier function, lymphostatin also functions as an adhesion factor for EPEC and EHEC, is essential for colonization of mouse and calf intestine, and regulates bacterial effector proteins., Summary: Lymphostatin is a common toxin in Gram negative bacteria with multiple functions: cell adhesion, immunosuppression, disruption of epithelial barrier function, and intestinal colonization.

The interactions of host-specific and microbial factors are responsible for recurrent urinary tract infections (rUTI). The anatomical properties of the female urogenital tract favor colonization by uropathogens. Local factors such as glucose concentration of the urine, stability of the lactobacilli population, the influence of estrogens, the activity of Tamm-Horsfall protein or of defensins, and disturbance of the systemic defense mechanisms dictate the course of an infection. The most prominent uropathogen is E. coli. It expresses various virulence factors including adhesions, toxins, iron uptake systems, and a capsule. It is still unclear if there are virulence factors characteristic for E. coli strains causing rUTI. The formation of intracellular reservoirs by invasion of uroepithelial cells by E. coli could be another, as yet little noticed cause for rUTI. Therefore, in cases of rUTI the application of intracellularly active antibiotics should be considered.

Periprosthetic infection is a significant complication in joint replacement surgery and develops in 0.5-2% of cases. Staphylococcus aureus and commensal microorganisms of the skin, especially coagulase-negative staphylococci, as well as a broad spectrum of other potential pathogens typically already colonize the surface of the foreign body at the time of implantation. Specific mechanisms such as bacterial adhesion to host factors absorbed in the material, biofilm formation, and a metabolic adaptation of adherent microorganisms play a particularly important role in the pathogenesis and course of the disease. Microbiological diagnosis requires to some extent complex culture procedures of puncture specimens or tissue removed during surgery; this can be supplemented by modern molecular testing. Antimicrobial treatment must be conceived as a synopsis of clinical picture, confirmed pathogen, and the intended surgical procedure on an individual basis and is routinely administered as combination therapy for several weeks, sometimes also as sequential therapy. Validated preventive measures in joint replacement surgery include mandatory perioperative antibiotic prophylaxis and other additional measures.

This study investigated the role of P fimbriae in colonization of Escherichia coli, host response, and bacterial persistence in humans. Human volunteers were inoculated intravesically with the nonadherent ABU isolate E. coli 83972 and with P fimbriated transformants of the same strain. During the following 24 h all urine samples, and thereafter daily samples, were collected for urine culture, analysis of neutrophil numbers, and cytokine concentrations (IL-6 and IL-8). The P fimbriated transformants showed enhanced bacterial colonization in comparison to E. coli 83972 and lowered the bacterial numbers needed for persistent bacteriuria. The P fimbriated transformants also lowered the bacterial numbers needed for a significant neutrophil and cytokine host response. We conclude that P fimbriae enhance bacterial colonization and trigger the host response in the human urinary tract.

Background: A major goal in research on intraocular lenses (IOL) is the development of new polymers and modifications to reduce foreign-body reactions after implantation. This effect may be achieved by a reduction in the surface hydrophobicity of the polymers. To illustrate the influence of surface modifications on bacterial adhesiveness, the most often isolated organism in "low-grade" postoperative endophthalmitis, Staphylococcus epidermidis, was used., Materials and Methods: For this reason three strains of this species, the type strain ATCC 14990 and two clinical isolates (8687, 6579 I) with different hydrophobic surface properties were studied. IOL, used in the experiments were either made of PMMA or silicone with modified surfaces (unpolished, polished, heparinized). The adhesiveness of H3-thymidin-labeled bacteria was calculated/mm2 of lens surface. Each experiment was performed in triplicate and repeated three times., Results: The hydrophobic-type strain showed stronger adherence to unpolished PMMA surface (8000 bacteria per mm2) compared to the polished (5200 bacteria/mm2). In contrast, the hydrophilic strain adhered with 2000 bacteria/mm2 to the unpolished and with 4200 bacteria/mm2 to the polished surface. Polishing PMMA lenses diminished the differences between the three strains. However, surface passivation of silicone lenses increased the adhesion rate of the hydrophilic strain up to 9600 bacteria/mm2. Treatment of PMMA lenses with heparin increased the adhesiveness of the hydrophilic strain and reduced the adhesion rate of the hydrophobic type strain to 250 bacteria/mm2., Conclusions: It was demonstrated that bacterial adherence to IOL also involves hydrophobic interactions. Obviously, however, that adherence reflects a complex of interactions between the two surfaces.

The classification of anaerobic infections and the most common organisms affecting the head and neck, pathogenesis diagnosis and current therapy are reported. Certain types of infections are particularly important for anaerobic bacteria and include actinomycosis, infectious complications of chronic otitis media or sinusitis, phlegmon of the floor of the mouth, peritonsillar abscess, retro-(para-)pharyngeal abscess, neck space infections, mediastinitis, wound infections following head and neck surgery and septic complications.

Adhesion of bacteria and adhesion of tumor cells have much in common, especially the participation of lectins in this process. In the future it might be possible to inhibit the metastatic process into the liver (e.g. during surgical operations of malignant tumors) and bacterial adherence to mucosal linings or plastic devices by blocking of adhesion molecules (lectins) with appropriate glycoconjugates. Initial clinical trials are very promising.

Bacteria adhere to and colonize almost any surface. The mechanism by which bacteria interact with the mucosal surface appears to involve specific molecular ligands or adhesins on the surface of the bacteria that interlock with specific receptor molecules on the surface to be colonized. Material adhesion allows the microorganisms to resist being washed away by the fluids and secretions that bathe mucosal surfaces and is a necessary prerequisite to growth, colonization, and subsequent infection. Many examples of the role of bacterial adherence to tissues of the host have been reported in the literature. The classic study is that of Smith and Linggood, who demonstrated that toxin-producing enteropathogenic Escherichia coli, which cause diarrhoea in swine, adhere selectively to the mucosal surfaces of the small intestine. Adherence is mediated by hair-like pili projecting from the surface of the cells. Production of these pili is controlled by a specific plasmid, the loss of which renders the cells avirulent although they continue to produce toxin. In addition, antibody to the pilus antigen prevents adherence and protects piglets against challenge with the piliated organisms. Thus, the adhesin is an essential virulence factor in enteropathogenic E. coli infections in swine. Similar studies in a variety of diseases including enterotoxigenic E. coli infections in men and rheumatic fever support the concept that specific bacterial adherence to host tissues is an important characteristic of many pathogenic microorganisms.

Unimpeded urinary flow and voiding of the bladder without residual urine are essential for the prevention of urinary tract infections. Therefore, recurrent urinary tract infections are most commonly found in patients with functional and anatomic disorders of the urinary tract. Children suffering from vesico-ureteral reflux are especially susceptible to recurrent urinary tract infections. The interaction between germ and target cell, i.e. between antigen and receptor, is another important factor in the development of urinary tract infections. This so-called bacterial adherence is variable and depends upon receptor density as well as the affinity of the germ to the receptor. However, our study showed that this bacterial adherence plays a minor role in the development of recurrent urinary tract infections secondary to vesico-ureteral reflux.