The development of showerhead biofilms exposes the user to repeated contact with potentially pathogenic microbes, yet we know relatively little about the content of these aggregates. The aim of the present study was to examine the microbial content of tape-like films found protruding from a domestic showerhead. Culturing showed that the films were dominated by aerobic α- and β-proteobacteria. Three isolates made up almost the entire plate count. These were a Brevundimonas species, a metalophilic Cupriavidus species and a thermophile, Geobacillus species. Furthermore, it was shown that the Cupriavidus isolate alone had a high capacity for biofilm formation and thus might be the initiator of biofilm production. A clone library revealed the same general composition. However, half of the 70 clones analyzed could not be assigned to a particular bacterial phylum and of these 29 differed from one another by only 1–2 base pairs, indicating a single species. Thus both the culture dependent and culture independent characterizations suggest a simple yet novel composition. The work is important as the biofilm is fundamentally different in form (tape-like) and content from that of all previously reported ones, where variously Mycobacterium, Methylobacterium and Xanthomonas species have dominated, and extremophiles were not reported.

A commercially available microarray (IDENTIBAC AMR-ve) for the detection of antibiotic resistance determinants was investigated for its potential to genotype 30 clinical isolates and two control strains of Klebsiella pneumoniae. Resistance profiles and the production of extended-spectrum β-lactamases were determined by disc diffusion and the results were compared with the microarray profiles in order to assess its scope and limitations. Genes associated with resistance to a wide range of antibiotics, including current first line therapy options, were detected. In addition, the array also detected class 1 integrases. The array is easy to use and interpret, and is useful in providing a general description of the numbers and types of resistance determinants in K. pneumoniae. It also provides an indication of the potential for resistance gene acquisition. However, in most instances detected resistance to specific antibiotics could not unequivocally be assigned to hybridization with a specific array probe. We conclude that the microarray is a valuable and rapid means of investigating the presence of resistance gene classes of therapeutic importance. It can also provide a starting point for selecting analyses of greater resolving power, such as phylogenetic subtyping by PCR sequencing.

The production of a drinking water that meets current aesthetic, microbiological and chemical standards, generally requires a combination of mechanical purification and disinfection in a multi-component treatment chain. Treatment choices and optimisation of water processing is best informed by using markers (including microbiological parameters) which indicate how each stage contributes to the production of the potable water. The present study combines culture-based and a number of culture-independent analyses to indicate what is happening at each stage of a state-of-the-art water treatment chain at Vansjø near the city of Moss in Norway. We show that particularly clarification with flotation and post-chlorination have profound and positive effects on water quality with respect to the removal and inactivation of microbes. Post-chlorination achieved better disinfection of the water than UV-treatment and was of paramount importance, as the penultimate step filtration through granular activated shed microbes to the water. Cloning and sequencing showed that some clones present in the raw water were detected at all stages in the treatment process, perhaps providing examples of microbes breaching physically all barriers in the treatment process. Results from the study should be useful in the improvement and maintenance of the treatment process at the Vansjø plant and others.

The presence of enterovirulent and/or antibiotic resistant strains of Escherichia coli in recreational bathing waters would represent a clear health issue. In total, 144 E. coli isolated from 26 beaches along the inner Oslo fjord were examined for virulence determinants and resistance to clinically important antibiotics. No isolates possessed the genetic determinants associated with enterotoxigenic strains and none showed the prototypic sorbitol negative, O157:H7 phenotype. A small number (∼1 %) produced alpha-hemolysin. Occurrences and patterns of antibiotic resistances were similar to those of E. coli isolated previously from environmental samples. In total, 6 % of the strains showed one or more clinically relevant resistances and 1.4 % were multi-drug resistant. Microarray analyses suggested that the resistance determinants were generally associated with mobile genetic elements. Resistant strains were not clonally related, and were, furthermore not concentrated at one or a few beach sites. This suggests that these strains are entering the waters at a low rate but in a widespread manner. The study demonstrates that resistant E. coli are present in coastal bathing waters where they can come into contact with bathers, and that the resistance determinants are potentially transferable. Some of the resistances registered in the study are to important antibiotics used in human medicine such as fluoroquinolones. The spread of antibiotic resistant genes, from the clinical setting to the environment, has clear implications with respect to the current management of bacterial infections and the long term value of antimicrobial therapy. The present study is the first of its kind in Norway.