Aims: The aim of this study is to determine the in vitro activity of allicin against Staphylococcus epidermidis and to evaluate the influence of allicin on biofilm formation. Methods and Results: In vitro activity of allicin (diallyl thiosulphinate) against 38 strains of S. epidermidis was investigated. The activity of allicin was similar against S. epidermidis methicillin susceptible and methicillin resistant strains [minimum inhibitory concentration (MIC) 90 ¼ 8 mg l)1 ]. In general, subinhibitory concentrations (sub-MIC) of allicin diminished biofilm formation in the five strains analysed. Conclusion:The results confirm the antibacterial effect of allicin. Sub-MICs of allicin also diminished the biofilm formations by S. epidermidis. Significance and Impact of the Study: The present study shows that allicin is active in vitro against S. epidermidis and that sub-MICs of allicin may play a role in the prevention of adherence of this bacteria to medical devices.

A knowledge of the physico-chemical surface properties of a bacterium is important to predict the rst step in the adhesion process of such a microorganism to biomaterials. In this work, hydrophobicity, surface free energy and surface charge of Enterococcus faecalis ATCC29212 and E. faecalis 72 bacterial strains have been analysed under the followings conditions, which were considered as criteria that could affect the thermodynamical parameters of the cell surface: culture medium was supplemented with serum and urine and the experiments were carried out in two different buffers (KPi and PBS) and at two temperatures (22 and 37 ± C). MATH hydrophobicity does not seem to be affected by temperature but water contact angle increased with temperature for both strains. Serum and urine added to the culture medium made the strains more and less hydrophobic, respectively. The zeta potential was dependent on the addition to the culture medium of serum and urine, the experimental temperature and the buffer employed and it decreased with increasing ionic strength in all cases studied. The results reveal that physico-chemical surface properties of bacteria are greatly affected by the environmental conditions in which they are measured, indicating that experiments should be carried out under experimental conditions as similar as possible to the situation of clinical interest.

The in vitro activity of moxifloxacin against 41 strains of coagulase-negative staphylococci was determined. A relationship between the activity of moxifloxacin and biofilm formation was detected. Biofilm-producing strains were more resistant to moxifloxacin than biofilm-negative strains. Our global results obtained with six strains of Staphylococcus epidermidis showed that subinhibitory concentrations of moxifloxacin did not significantly modify biofilm formation. On the other hand, moxifloxacin concentrations of 2, 10, 50 and 100 × MIC produced a log decrease in viable count (included in a biofilm) of 0.20, 0.37, 1.10 and 1.69, respectively.

Background Resistance to traditional antifungal agents is a considerable health problem nowadays, aggravated by infectious processes related to biofilm formation, usually on implantable devices. Therefore, it is necessary to identify new antimicrobial molecules, such as natural products, to develop new therapeutic strategies to prevent and eradicate these infections. One promising product is propolis, a natural resin produced by honeybees with substances from various botanical sources, beeswax and salivary enzymes. The aim of this work was to study the effect of a new Spanish ethanolic extract of propolis (SEEP) on growth, cell surface hydrophobicity, adherence and biofilm formation of Candida glabrata, a yeast capable of achieving high levels of resistance to available anti-fungal agents. Methods The antifungal activity of SEEP was evaluated in the planktonic cells of 12 clinical isolates of C. glabrata. The minimum inhibitory concentration (MIC) of propolis was determined by quantifying visible growth inhibition by serial plate dilutions. The minimum fungicide concentration (MFC) was evaluated as the lowest concentration of propolis that produced a 95% decrease in cfu/mL, and is presented as MFC50 and MFC90, which corresponds to the minimum concentrations at which 50 and 90% of the C. glabrata isolates were inhibited, respectively. Influence on cell surface hydrophobicity (CSH) was determined by the method of microbial adhesion to hydrocarbons (MATH). The propolis effect on adhesion and biofilm formation was determined in microtiter plates by measurement of optical density (OD) and metabolic activity (XTT-assay) in the presence of sub-MIC concentrations of SEEP. Results SEEP had antifungal capacity against C. glabrata isolates, with a MIC50 of 0.2% (v/v) and an MFC50 of 0.4%, even in azole-resistant strains. SEEP did not have a clear effect on surface hydrophobicity and adhesion, but an inhibitory effect on biofilm formation was observed at subinhibitory concentrations (0.1 and 0.05%) with a significant decrease in biofilm metabolism. Conclusions The novel Spanish ethanolic extract of propolis shows antifungal activity against C. glabrata, and decreases biofilm formation. These results suggest its possible use in the control of fungal infections associated with biofilms.

In vitro resistance of community-acquired and nosocomial strains of Enterococcus faecalis isolated in Badajoz (Spain) were determined by a microdilution method. The isolates were identified with conventional MicroScan Pos Combo 4 I dehydrated panels. No resistance to glycopeptides was found, but LY333328 was 2–4 times more active than vancomycin. In the nosocomial strains, high-level resistance to streptomycin (HLRS) was 54.7%, and high-level resistance to gentamicin (HLRG) was 38.1%. Resistance to ciprofloxacin and trovafloxacin was 45.3 and 38.9%, respectively. In the community-acquired isolates, HLRS, HLRG, resistance to ciprofloxacin and resistance to trovafloxacin were 44.2, 17.3, 15.4 and 13.5%, respectively. Trovafloxacin was 2–4 times more active than ciprofloxacin against both groups of strains. An association between high-level resistance to aminoglycosides and resistance to fluoroquinolones was noted. The resistance to aminoglycosides did not influence the activity of vancomycin and LY333328.

Objectives: Staphylococcus aureus is the leading cause of surgical site infection, and roughly 25−30% of the population are colonised. In general, colonised patients have a 2−14 fold increased risk of infection, but those patients that carry at higher levels are at highest risk. The patient's own nasal flora account for 80% of S. aureus infections. Rapidly identifying colonised patients provides the ability to proactively manage S. aureus carriers for the prevention of infection. The objective of this pilot study was to investigate the clinical performance of a new rapid diagnostic test system (for proposed introduction in 2007 under the trade designation 3M Rapid Detect Staph aureus) to identify high level carriage of S. aureus directly from nasal swabs. Methods: This was a multi-centre, prospective, comparative pilot study. There were a total of four sites, two in Europe and in the United States that screened and sampled healthy subjects. One nasal sample was collected from both nares using a swab. The sample was analysed by the 3M Rapid Detect diagnostic test system, which provides results in approximately 20 minutes and a standard quantitative culture method using a selective medium. Confirmation testing was conducted using the Tube Coagulase Test. Results: A total of 1044 subjects were enrolled across four sites with a total of 999 evaluable subjects (having both culture and detector results). 33.6% of all evaluable subjects were S. aureus carriers, while 12.4% carried 5000 cfu (high level carriers). The mean level of carriage for those who were positive was 3.23 Logs (Range 0.63-6.50 Logs). The sensitivity of the test at 5000 cfu was 87% (95% CI: 80−92%). The overall sensitivity of the test system was 51% (95% CI: 46−57%). The overall specificity was 92% (95% CI: 90−94%). At 5000 cfu the negative predictive value was 98% (95% CI: 97−99%) while the positive predictive value for all levels of carriage was 76% (95% CI: 70−82%). Based on a positive test result 77% of all patients are not treated preemptively. Conclusions:The proposed 3M Rapid Detect diagnostic test system proved to be a sensitive tool to identify subjects carrying high numbers of S. aureus in the nares. Especially, the high negative predictive value provides a screening tool to rapidly and accurately identify patients who are at low risk of developing a S. aureus infection after surgery, thus allowing for more targeted use of antibiotics and other infection control measures.