The perfused biofilm fermenter was found to be unsuitable for the long-term culture and growth rate control of Staphylococcus aureus and Pseudomonas aeruginosa biofilms. In a simplified approach, biofilms of these organisms were grown within Sorbarod filter plugs which were perfused with culture medium. Pseudo-steady states were established which were stable over several days at which the growth rate of the biofilm was reproducible, measurable and significantly slower than in broth culture. Environmental scanning electron microscopy of dissected Sorbarods demonstrated an association of cells with the surfaces of individual cellulose fibres, and growth characteristic of biofilms. Relatively high cell numbers recovered from the Sorbarod model facilitated biochemical investigations of biofilm populations and cells released spontaneously from them. SDS-PAGE demonstrated significant differences between the protein profiles of biofilm and eluted populations, which include, in Staph. aureus, the repression of a 48 kDa protein and increased expression of a 21 kDa protein relative to planktonic controls cultured at equivalent growth rates. The paper demonstrates the suitability of the approach for the culture of biofilm samples which are suitable for biochemical analysis.

The in vitro activity of a new oral antimicrobial agent, norfloxacin (MK-0366), was compared with those of nalidixic acid, nitrofurantoin, co-trimoxazole, trimethoprim, sulfamethoxazole, cinoxacin, tetracycline, ampicillin, carbenicillin, and cephalexin against 628 urinary bacterial isolates. Norfloxacin was the most active antimicrobial agent tested against the gram-negative bacilli. It was less active than a few of the other antimicrobial agents against enterococci and Staphylococcus aureus.

A bioluminescent Pseudomonas aeruginosa was incorporated into an in vitro static diffusion method to determine whether light output could be used as a measure of wound dressing efficacy. A significant linear correlation was observed between viable counts and bioluminescence during exponential growth in planktonic culture (r 2 ‫؍‬ 0.969). Exponential-phase cells were used to inoculate cellulose discs for integration into an in vitro wound model that incorporated a reservoir of serum. A significant linear correlation was found between bioluminescence (photon counts monitored by a low-light camera) and viable counts in this growth environment (r 2 ‫؍‬ 0.982). Three antimicrobial wound dressings were applied to the surface of freshly prepared sample discs within the wound model, and the kill kinetics were codetermined by photon and viable counts. Quantifiable kill rates gave the same order of efficacy for the three wound dressings using both types of measurement, and a significant linear correlation was shown between photon and viable counts (r 2 ‫؍‬ 0.873) within this killing environment. Under all defined conditions, a significant linear correlation between bioluminescence and viable counts was shown but the actual slope of the correlation was different, depending on the physicochemical environment of the cells. Hence, significantly more light per cell (P < 0.0001) was produced when cells in discs were exposed to a killing environment compared to a growing environment. As long as defined conditions are employed, the resulting linear correlation enables the state of the system to be continually monitored without disturbance, allowing more immediate and accurate calculations of kill rates without the need for viable counting.

The application of a bioluminescent reporter strain to biofilm research provides valuable real-time positional data on the efficacy of anti-biofilm treatment strategies.

The bacteriophage vB_SenS-Ent1 (Ent1) is a member of the family Siphoviridae of tailed bacteriophages and infects a broad range of serovars of the enteric pathogen Salmonella enterica. The virion particle is composed of an icosahedral head 64 nm in diameter and a flexible, non-contractile tail of 116 ¾ 8.5 nm possessing terminal fibres. The adsorption rate constant at 37 6C is 6.73 ¾ 10 "9 ml min "1 . Latent and eclipse periods are 25 and 20 min, respectively, and the burst size is 35 progeny particles per cell after 35 min at 37 6C. Sequencing revealed a circularly permuted, 42 391 bp dsDNA genome containing 58 ORFs organized into four major transcriptional units. Comparisons with the genome sequences of other bacteriophages revealed a high level of nucleotide sequence identity and shared orthologous proteins with the Salmonella phages SETP3, SE2 and KS7 (SS3e) and the Escherichia phages K1G, K1H, K1ind1 and K1ind3. INTRODUCTIONSalmonellae are Gram-negative, facultatively anaerobic, non-sporulating and generally motile bacilli that are causative agents of typhoid fever, gastroenteritis and enteric fever in both humans and animals. The species Salmonella enterica is classified into five subspecies by differential biochemistry and further subdivided into serotypes based upon serology of the lipopolysaccharide (LPS) (O) and flagellar (H) antigens (Grimont & Weill, 2007). Epidemiological surveillance data present serovars of Salmonella enterica subspecies enterica as prominent aetiological agents of bacterial food-borne disease worldwide (ECDC, 2010;Scallan et al., 2011). Non-typhoidal infections by Salmonella serovars other than Typhi and Paratyphi are generally self-limiting, with clinical manifestations ranging from mild to severe gastroenteritis. In a small proportion of cases, further complications arise, including bacteraemia, gastrointestinal bleeding and focal infections (Acheson & Hohmann, 2001). Transmission to humans is primarily associated with the ingestion of a wide variety of contaminated food products, but may also arise by contact with animals, contaminated water and infected individuals (Hanning et al., 2009). In the USA, the economic burden associated with medical care and lost productivity due to salmonellosis is estimated at several billion dollars annually (Voetsch et al., 2004).All Salmonella phages reported thus far belong to the order Caudovirales (tailed phages) and represent three families: the Siphoviridae, Podoviridae and Myoviridae. Of these, only a small fraction are lytic, whilst the majority are capable of a temperate life cycle (Kropinski et al., 2007). Lysogeny is widespread among strains of Salmonella and most, if not all, harbour prophages. To date, the complete genome sequences of 36 Salmonella phages are publicly available, representing just 3.97 % (35/880) of all available bacteriophage genome sequences. With an estimated 10 31 bacteriophages existing in the environment (Suttle, 2005;Whitman et al., 1998), current knowledge is limited regarding the identification and characte...