Staphylococcus aureus biofilms are a significant problem in health care settings, partly due to the presence of a nondividing, antibiotic-tolerant subpopulation. Here we evaluated treatment of S. aureus UAMS-1 biofilms with HT61, a quinoline derivative shown to be effective against nondividing Staphylococcus spp. HT61 was effective at reducing biofilm viability and was associated with increased expression of cell wall stress and division proteins, confirming its potential as a treatment for S. aureus biofilm infections.

ABSTRACT Periprosthetic infection (PI) causes significant morbidity and mortality after fixation and joint arthroplasty and has been extensively linked to the formation of bacterial biofilms. Poly(methyl methacrylate) (PMMA), as a cement or as beads, is commonly used for antibiotic release to the site of infection but displays variable elution kinetics and also represents a potential nidus for infection, therefore requiring surgical removal once antibiotics have eluted. Absorbable cements have shown improved elution of a wider range of antibiotics and, crucially, complete biodegradation, but limited data exist as to their antimicrobial and antibiofilm efficacy. Synthetic calcium sulfate beads loaded with tobramycin, vancomycin, or vancomycin-tobramycin dual treatment (in a 1:0.24 [wt/wt] ratio) were assessed for their abilities to eradicate planktonic methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus epidermidis relative to that of PMMA beads. The ability of the calcium sulfate beads to prevent biofilm formation over multiple days and to eradicate preformed biofilms was studied using a combination of viable cell counts, confocal microscopy, and scanning electron microscopy of the bead surface. Biofilm bacteria displayed a greater tolerance to the antibiotics than their planktonic counterparts. Antibiotic-loaded beads were able to kill planktonic cultures of 106 CFU/ml, prevent bacterial colonization, and significantly reduce biofilm formation over multiple days. However, established biofilms were harder to eradicate. These data further demonstrate the difficulty in clearing established biofilms; therefore, early preventive measures are key to reducing the risk of PI. Synthetic calcium sulfate loaded with antibiotics has the potential to reduce or eliminate biofilm formation on adjacent periprosthetic tissue and prosthesis material and, thus, to reduce the rates of periprosthetic infection.

An increasing number of reports suggest that Propionibacterium acnes can cause serious invasive infections. Currently, only limited data exist regarding the spectrum of invasive P. acnes infections. We conducted a non-selective cohort study at a tertiary hospital in the UK over a 9-year-period (2003-2012) investigating clinical manifestations, risk factors, management, and outcome of invasive P. acnes infections. Forty-nine cases were identified; the majority were neurosurgical infections and orthopaedic infections (n = 28 and n = 15 respectively). Only 2 cases had no predisposing factors; all neurosurgical and 93.3 % of orthopaedic cases had a history of previous surgery and/or trauma. Foreign material was in situ at the infection site in 59.3 % and 80.0 % of neurosurgical and orthopaedic cases respectively. All neurosurgical and orthopaedic cases required one or more surgical interventions to treat P. acnes infection, with or without concomitant antibiotic therapy; the duration of antibiotic therapy was significantly longer in the group of orthopaedic cases (median 53 vs 19 days; p = 0.0025). All tested P. acnes isolates were susceptible to penicillin, ampicillin and chloramphenicol; only 1 was clindamycin-resistant. Neurosurgical and orthopaedic infections account for the majority of invasive P. acnes infections. Most cases have predisposing factors, including previous surgery and/or trauma; spontaneous infections are rare. Foreign material is commonly present at the site of infection, indicating that the pathogenesis of invasive P. acnes infections likely involves biofilm formation. Since invasive P. acnes infections are associated with considerable morbidity, further studies are needed to establish effective prevention and optimal treatment strategies.

In the absence of sufficient cleaning of medical instruments, contamination and infection can result in serious consequences for the health sector and remains a significant unmet challenge. In this paper we describe a novel cleaning system reliant on cavitation action created in a free flowing fluid stream where ultrasonic transmission to a surface, through the stream, is achieved using careful design and control of the device architecture, sound field and the materials employed. Cleaning was achieved with purified water at room temperature, moderate fluid flow rates and without the need for chemical additives or the high power consumption associated with conventional strategies. This study illustrates the potential in harnessing an ultrasonically activated stream to remove biological contamination including brain tissue from surgical stainless steel substrates, S. epidermidis biofilms from glass, and fat/soft tissue matter from bone structures with considerable basic and clinical applications.

Acidogenic bacteria within dental plaque biofilms are the causative agents of caries. Consequently, maintenance of a healthy oral environment with efficient biofilm removal strategies is important to limit caries, as well as halt progression to gingivitis and periodontitis. Recently, a novel cleaning device has been described using an ultrasonically activated stream (UAS) to generate a cavitation cloud of bubbles in a freely flowing water stream that has demonstrated the capacity to be effective at biofilm removal. In this study, UAS was evaluated for its ability to remove biofilms of the cariogenic pathogen Streptococcus mutans UA159, as well as Actinomyces naeslundii ATCC 12104 and Streptococcus oralis ATCC 9811, grown on machine-etched glass slides to generate a reproducible complex surface and artificial teeth from a typodont training model. Biofilm removal was assessed both visually and microscopically using high-speed videography, confocal scanning laser microscopy (CSLM), and scanning electron microscopy (SEM). Analysis by CSLM demonstrated a statistically significant 99.9% removal of S. mutans biofilms exposed to the UAS for 10 s, relative to both untreated control biofilms and biofilms exposed to the water stream alone without ultrasonic activation (P < 0.05). The water stream alone showed no statistically significant difference in removal compared with the untreated control (P = 0.24). High-speed videography demonstrated a rapid rate (151 mm(2) in 1 s) of biofilm removal. The UAS was also highly effective at S. mutans, A. naeslundii, and S. oralis biofilm removal from machine-etched glass and S. mutans from typodont surfaces with complex topography. Consequently, UAS technology represents a potentially effective method for biofilm removal and improved oral hygiene.

Introduction Bacterial biofilms are structured communities of adherent bacteria enveloped in self-produced matrix which are refractory to antibiotics and the host immune response. They play a key role in the chronicity of respiratory infection in cystic fibrosis. Haemophilus influenzae is the most common pathogen isolated in primary ciliary dyskinesia (PCD). We hypothesise that impaired mucociliary clearance in PCD will predispose these patients to biofilm infections. Aims To investigate the biofilm-forming capacity of clinical H. influenzae isolates from PCD patients. Methods The biofilm-forming ability of 4 H. influenzae clinical isolates from different PCD patients were compared using a crystal violet (CV) assay, colony forming unit counts (CFUs), fluorescence in situ hybridisation (FISH) and scanning electron microscopy (SEM). Results CV staining demonstrated bacterial biomass adherent to plastic for all isolates (OD600 0.04 for isolate 1 to 0.12 for isolate 4, p<0.05). SEM permitted visualisation of a characteristic matrix surrounding the bacteria. Biofilm thickness varied for each isolate, qualified by FISH (13μm for isolate 1; 82μm for isolate 4). CFUs quantified the number of viable bacteria within each day 4 biofilm, ranging from 9x106 CFU/cm2 in isolate 1 to 2x108 CFU/cm2 in isolate 4. Conclusion We have characterised biofilm-forming capacity in all 4 H. influenzae isolates from PCD patients. 2 isolates from chronically colonised patients (over 4 years) consistently formed thicker, cell dense and structurally more complex biofilms than the other, more recently isolated, strains. These data suggest that H. influenzae is capable of biofilm formation and that PCD patients, like cystic fibrosis, might harbour bacteria in biofilms.

Current World Health Organization guidelines pertaining to the reprocessing of surgical instruments in the face of potential iatrogenic transmission of Creutzfeldt-Jakob disease (iCJD) are incompatible for the vast majority of devices. This has led to the advent of a range of new decontamination measures. Even without the implementation of these new procedures, the incidence of proven iCJD through surgery remains low. In this study, existing decontamination processes in sterile service departments have been evaluated using simulated washer-disinfector cycles on surgical grade stainless steel wires inoculated with ME7 scrapie homogenate. The consequence of varying the soil drying times and choice of cycle pre-treatment on prion removal were evaluated. Assessment of residual contamination at each cycle phase was carried out with the application of a sensitive fluorescent staining procedure to identify both total protein and prion-associated amyloid. The study confirmed that immediate reprocessing following contamination was beneficial during the pre-treatment phase with either an enzymatic or pre-soak wetting agent. Final total protein levels at the end of the cycles, were not significantly different from those where the soil was allowed to dry. In addition, cycles involving a pre-treatment with either an enzymatic cleaner or pre-soak, whether the soil was allowed to dry or not, showed complete removal of detectable prion amyloid. The results suggest that current decontamination procedures, combined with immediate processing of surgical instruments, have the potential to be highly effective alone at reducing the risk of surgical transmission of CJD.

Using Episcopic Differential Interference Contrast (EDIC) microscopy, this study has investigated the potential reapplication of prote ina ceouscontami napotential reapplication of proteinaceous contamination onto surgical instruments following a washer-disinfector cycle through the handling of staff within the clean room. The deposition of 0.51 ng/mm2 of protein onto surgical grade stainless steel by one finger print alone has been demonstrated. Moreover, using a previously described contamination index, a 5 to 10-fold increase in protein present on surgical instruments was noted following handling by clean-room staff under current departmental practices, relative to instruments handled by staff wearing gloves. While unlikely to pose a direct risk to patient health, subsequent sterilisation will fix protein to an instrument surface thereby decreasing the effectiveness of further decontamination cycles. Current guidelines make no recommendations surrounding the use of gloves by staff working within the clean room. However it is clear that this matter must be reviewed to limit the unnecessary transference of protein to surgical instruments.