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In the process of endourological development a great variety of foreign bodies have been invented besides urinary catheters on which biofilm can be formed. Bacteria in the biofilm are less sensible to antibiotics. An additional problem of medical biomaterials in the urinary tract environment is the development of encrustation and consecutive obstruction. In this review, we tried to sum up the conditions where biofilm formation has a great impact on the development or maintenance of urological infections and on treatment success. Modification of the biomaterial surface seems to be the most promising prevention strategy for bacterial biofilms. Easier methods for diagnosing and quantifying biofilm infection, to develop more specific antimicrobial agents and ideal device surfaces would surely help the fight against biofilm formation.

We investigated whether trace elements in tail feathers of an insectivorous and long‐distance migratory bird species could be used to identify moulting areas and hence migratory pathways. We analysed tail feathers from birds of different age and sex collected from a range of different breeding sites across Europe. The site of moult had a large effect on elemental composition of feathers of birds, both at the European and African moulting sites. Analysis of feathers of nestlings with known origin suggested that the elemental composition of feathers depended largely upon the micro‐geographical location of the colony. The distance between moulting areas could not explain the level of differences in trace elements. Analysis of feathers grown by the same individuals on the African wintering grounds and in the following breeding season in Europe showed a large difference in composition indicating that moulting site affects elemental composition. Tail feathers moulted in winter in Africa by adults breeding in different European regions differed markedly in elemental composition, indicating that they used different moulting areas. Analysis of tail feathers of the same adult individuals in two consecutive years showed that sand martins in their first and second wintering season grew feathers with largely similar elemental composition, although the amounts of several elements in tail feathers of the older birds was lower. There was no difference between the sexes in the elemental composition of their feathers grown in Africa. Investigation of the trace element composition of feathers could be a useful method for studying similarity among groups of individuals in their use of moulting areas.

Heritable hypermutation in bacteria is mainly due to alterations in the methyl-directed mismatch repair (MMR) system. MMR-deficient strains have been described from several bacterial species, and all of the strains exhibit increased mutation frequency and recombination, which are important mechanisms for acquired drug resistance in bacteria. Antibiotics select for drug-resistant strains and refine resistance determinants on plasmids, thus stimulating DNA recombination via the MMR system. Antibiotics can also act as indirect promoters of antibiotic resistance by inducing the SOS system and certain error-prone DNA polymerases. These alterations have clinical consequences in that efficacious treatment of bacterial infections requires high doses of antibiotics and/or a combination of different classes of antimicrobial agents. There are currently few new drugs with low endogenous resistance potential, and the development of such drugs merits further research. IntroductionEradication of infectious diseases is constantly challenged by micro-organisms that develop new survival strategies. Previous studies suggest that mutational events play a predominant role in bacterial adaptation and confer a selective advantage (Chou et al., 2009;Cooper, 2007). Early experiments aimed at detecting mutators used mutagenized laboratory strains of bacteria, sometimes coupled with different selection strategies. LeClerc et al. (1996) reported high mutation frequency among Escherichia coli and Salmonella pathogens, challenging the theory that mutators were rare among bacterial populations. Taken together, these findings demonstrated that natural populations could respond to environmental selection in two ways, i.e. by enhanced mutation frequencies and by recombination. Transient mutator status, which involves reversion or recombination within the mutator alleles or depletion of the methyl-directed mismatch repair (MMR) system proteins, allows the organism to temporarily benefit from the elevated mutation frequency for adaptation while reducing the risk of accumulating deleterious mutations. Using a mathematical model, Rosche & Foster (1999) showed that transient hypermutators play a role in adaptive mutation in E. coli. Molecular mechanisms of hypermutationProteins involved in the DNA mismatch repair pathway help replace nucleotides introduced erroneously into the replicated DNA and also hinder recombination between non-identical DNA sequences. Deficiencies in any of the DNA mismatch repair pathway mechanisms can lead to a hypermutator phenotype. DNA repairSiegel & Bryson (1967) discovered the mutS gene in an azaserine-resistant derivative of E. coli that had a mutator phenotype and carried a deletion in the mutS gene. The majority of naturally occurring strong mutators have defects in the MMR system; the mutations are mainly in mutS (Oliver et al., 2002), but deletions in genes encoding beta-clamp proteins and in mutH, mutL and mutU (uvrD) have also been described (Fig. 1). Inactivation of basal excision repair genes, e.g. mutY, mutM, ...

The aim of this present study was determination of essential and toxic element concentrations