Viable Methicillin-resistant Staphylococcus Aureus Research Articles

Heat Inactivation of Methicillin-Resistant Staphylococcus aureus Strains from German Dairy farms in Colostrum and Raw Milk.

Methicillin-resistant Staphylococcus aureus (MRSA) may cause difficult-to-treat infections in dairy cattle. One possible route of MRSA transmission into calves is via the feeding of contaminated waste milk. We tested the heat resistance of 17 MRSA strains isolated from German dairy farms in colostrum and raw milk in a laboratory approach. Heating colostrum or raw milk at 60 °C for 30 min eliminated all viable MRSA in the milk, provided the MRSA inoculation rate is low (103 cfu mL-1). In contrast, raw milk highly inoculated with MRSA (106 cfu mL-1) required a holding time of at least 30 min at 70 °C to fully eliminate MRSA from it. However, quantitative analysis showed that a heat treatment for 10 min at 60 °C already significantly reduced the number of viable MRSA in highly inoculated raw milk. Heating colostrum and raw milk above 60 °C may destroy immunoglobulins which are crucial for the calf's health. Therefore, we suggest that colostrum and raw milk that is to be fed to calves on MRSA-positive dairy farms is heated at 60 °C for at least 10 min to reduce the likelihood of transmitting MRSA. In addition, the 60 °C heat-treated colostrum/raw milk should be fed to the calves as soon as possible to avoid re-growth of viable MRSA.

Experimental Acquisition, Maintenance, and Transmission of Methicillin-Resistant Staphylococcus aureus by the Common Bed Bug, Cimex lectularius.

Here, we fed bed bugs through a membrane contaminated with methicillin-resistant Staphylococcus aureus (MRSA) at a concentration naturally present on human skin. We then determined the amount of viable MRSA present on their surface and internally over a period of 7 days. We also determined whether bed bugs that fed through the contaminated membrane could transmit MRSA to an uncontaminated membrane when taking a second blood meal 7 days later. Bed bugs acquired MRSA both externally on the cuticle surface as well as internally when feeding. MRSA was found to persist for 7 days both externally and internally in some bed bugs. Furthermore, MRSA replicated internally but not externally. Most importantly, bed bugs were able to transmit MRSA to an uncontaminated membrane feeder in 2 of 3 trials. These findings provide the first experimental support for the hypothesis that bed bugs may contribute to the transmission of MRSA in some settings.

Reassessing the forgotten cure: Efficacy of bacteriophage as a therapeutic agent against MRSA in diabetic rats

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the leading causes of increased amputation, morbidity and mortality among patients with diabetic foot infections. These infections are refractory to antibiotics. Therefore, alternative therapy using phages has re-emerged as a promising option to treat such infections. The present study was conducted to evaluate the efficacy of phage in treating diabetic wound infection caused by MRSA 43300 in rats. Phages were isolated against MRSA 43300 and purified as per standard procedures. Diabetes was induced in healthy albino rats using streptozotocin. The minimum lethal dose (MLD) of MRSA and minimum protective dose (MPD) of phage was identified. A full-size excision wound was created on the back of rats. The rats were divided into five groups (Group I – Non-infected and untreated, Group II- Infected and untreated, Group III - Infected and phage challenged, Group IV- Infected and antibiotic treated, Group V – Non-infected and phage treated). Groups II, III and IV were infected with MLD of MRSA 43300. After 48 h of infection, Group III was treated with a single dose of MPD of phage and group IV was treated with mupirocin on all days. The wound were sampled on designated days, Gram stain was done to detect for the presence of pus cells and Gram positive cocci. Standard culture methods were used to confirm the presence of phage and MRSA 43300 and estimate their titre on different days among different groups. Wound contraction rate was recorded to compare the duration of wound healing between all the groups. Group II served as bacterial control in which all the rats died after 72h. The phage treated group III showed the presence of Gram positive cocci and pus cells in Gram stain till 6 days. Viable MRSA was isolated till 4 days post treatment and more than 50% of the wound contracted by day 12 of infection. Phage-treated group showed better wound contraction rate and faster bacterial clearance compared to antibiotic-treated group. The results of the present study help to reconsider phage therapy for treatment of drug-resistant infection.

A Bacteriophage-Based Electrochemical Biosensor for Detection of Methicillin-Resistant Staphylococcus aureus

Bacterial pathogens are important targets for detection and early diagnostics of infection in healthcare. Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterium that can cause severe complications such as pneumonia and septicemia from surgical site infections. In this work, a carbon nanotube (CNT)-based impedimetric biosensor using SATA-8505, a bacteriophage, as a recognition element was developed for the detection of MRSA USA300, a common strain of MRSA found in surgical infections. The biosensor allows for fast and selective detection of viable MRSA cells by measuring impedance changes on the electrode surface as a result of bacterial capture by the phage-functionalized CNT electrode. The immobilization of the bacteriophage was achieved by inducing an electric-field and using a charge-directed orientation strategy, and activity of the immobilized phage was confirmed by an infectivity study using disk diffusion methods. The biosensing platform showed high selectivity and sensitivity toward MRSA USA300 with a limit of detection of 1.23 × 102 CFU/ml in aqueous solution and 1.29 × 102 CFU/ml in blood plasma. The biosensing platform could potentially be integrated into a lab-on-a-chip platform for point of care use and for other pathogens such as Pseudomonas aeruginosa, Klebsiella and Listeria monocytogenes.

Colonization of Environmental Methicillin-Resistant Staphylococcus Aureus in a Newly Constructed Children's Outpatient Clinic

<h3>Background</h3> The purpose of this study was to examine prevalence of environmental methicillin-resistant Staphylococcus aureus (MRSA) in a newly constructed children's outpatient clinic. Viable MRSA on floors and select surfaces in waiting areas and two medical units were compared for the last 3 months of construction through the first 6 months of occupation. <h3>Methods</h3> A total of 52 locations were swabbed weekly, including common areas (floors at check-in desks, waiting rooms, and on children's toys), and on patient room floors, counters, and return air ducts in pulmonary and general medicine units (3 rooms tested in each). Testing was performed during the last 3 months of construction (October-December 2018), and the first 6 months after opening (January - June 2019). HardyCHROM MRSA selective and differential agar media was used to identify viable MRSA. <h3>Results</h3> In common areas, during construction we observed 4/80 (5%) positive swabs for MRSA. After occupation, 72 /208 (35%) positive swabs for MRSA were found in the common areas. In pulmonary unit rooms during construction we observed 3/60 (5%) positive samples for MRSA, and 52/234 (22%) positive samples for MRSA after occupation (p < 0.01). In general medicine rooms during construction we observed 10/60 (17%) positive MRSA samples and 75/234 (32%) positive samples for MRSA after occupation (p < 0.01). Significant differences in the presence of viable MRSA between construction and occupation phases were found in the the common area as well (p < 0.01). <h3>Conclusions</h3> This study shows the rapid colonization of the clinical environment with MRSA within the first 6 months of opening of a children's outpatient clinic. The potential link between environmental bacteria and healthcare-associated infections is an important area of research in infectious disease, particularly for outpatient clinics, requiring monitoring studies such as this.

Viable bacterial communities on hospital window components in patient rooms.

Previous studies demonstrate an exchange of bacteria between hospital room surfaces and patients, and a reduction in survival of microorganisms in dust inside buildings from sunlight exposure. While the transmission of microorganisms between humans and their local environment is a continuous exchange which generally does not raise cause for alarm, in a hospital setting with immunocompromised patients, these building-source microbial reservoirs may pose a risk. Window glass is often neglected during hospital disinfection protocols, and the microbial communities found there have not previously been examined. This pilot study examined whether living bacterial communities, and specifically the pathogens Methicillin-resistant Staphylococcus aureus (MRSA) and Clostridioides difficile (C. difficile), were present on window components of exterior-facing windows inside patient rooms, and whether relative light exposure (direct or indirect) was associated with changes in bacterial communities on those hospital surfaces. Environmental samples were collected from 30 patient rooms in a single ward at Oregon Health & Science University (OHSU) in Portland, Oregon, USA. Sampling locations within each room included the window glass surface, both sides of the window curtain, two surfaces of the window frame, and the air return grille. Viable bacterial abundances were quantified using qPCR, and community composition was assessed using Illumina MiSeq sequencing of the 16S rRNA gene V3/V4 region. Viable bacteria occupied all sampled locations, but was not associated with a specific hospital surface or relative sunlight exposure. Bacterial communities were similar between window glass and the rest of the room, but had significantly lower Shannon Diversity, theorized to be related to low nutrient density and resistance to bacterial attachment of glass compared to other surface materials. Rooms with windows that were facing west demonstrated a higher abundance of viable bacteria than those facing other directions, potentially because at the time of sampling (morning) west-facing rooms had not yet been exposed to sunlight that day. Viable C. difficile was not detected and viable MRSA was detected at very low abundance. Bacterial abundance was negatively correlated with distance from the central staff area containing the break room and nursing station. In the present study, it can be assumed that there is more human traffic in the center of the ward, and is likely responsible for the observed gradient of total abundance in rooms along the ward, as healthcare staff both deposit more bacteria during activities and affect microbial transit indoors. Overall, hospital window components possess similar microbial communities to other previously identified room locations known to act as reservoirs for microbial agents of hospital-associated infections.

Antimicrobial Peptide P60.4Ac-Containing Creams and Gel for Eradication of Methicillin-Resistant Staphylococcus aureus from Cultured Skin and Airway Epithelial Surfaces.

We previously found the LL-37-derived peptide P60.4Ac to be effective against methicillin-resistant Staphylococcus aureus (MRSA) on human epidermal models (EMs). The goal of this study was to identify the preferred carrier for this peptide for topical application on skin and mucosal surfaces. We prepared P60.4Ac in three formulations, i.e., a water-in-oil cream with lanolin (Softisan 649), an oil-in-water cream with polyethylene glycol hexadecyl ether (Cetomacrogol), and a hydroxypropyl methylcellulose (hypromellose) 4000 gel. We tested the antimicrobial efficacy of the peptide in these formulations against mupirocin-resistant and -sensitive MRSA strains on EMs and bronchial epithelial models (BEMs). The cytotoxic effects of formulated P60.4Ac on these models were determined using histology and WST-1 and lactate dehydrogenase assays. Moreover, we assessed the stability of the peptide in these formulations with storage for up to 3 months. Killing of MRSA by P60.4Ac in the two creams was less effective than that by P60.4Ac in the hypromellose gel. In agreement with those findings, P60.4Ac in the hypromellose gel was highly effective in eradicating the two MRSA strains from EMs. We found that even 0.1% (wt/wt) P60.4Ac in the hypromellose gel killed >99% of the viable planktonic bacteria and >85% of the biofilm-associated bacteria on EMs. Hypromellose gels containing 0.1% and 0.5% (wt/wt) P60.4Ac effectively reduced the numbers of viable MRSA cells from BEMs by >90%. No cytotoxic effects of P60.4Ac in the hypromellose gel with up to 2% (wt/wt) P60.4Ac on keratinocytes in EMs and in the hypromellose gel with up to 0.5% (wt/wt) P60.4Ac on epithelial cells in BEMs were observed. High-performance liquid chromatography analysis showed that P60.4Ac was stable in the Softisan cream and the hypromellose gel but not in the Cetomacrogol cream. We conclude that P60.4Ac formulated in hypromellose gel is both stable and highly effective in eradicating MRSA from colonized EMs and BEMs.

Detection of Airborne Methicillin-Resistant Staphylococcus aureus Inside and Downwind of a Swine Building, and in Animal Feed: Potential Occupational, Animal Health, and Environmental Implications

ABSTRACTAerosolized methicillin-resistant Staphylococcus aureus (MRSA) was sampled inside and downwind of a swine facility. Animal feed was sampled before and after entry into the swine facility. Aerosolized particles were detected using an optical particle counter for real-time measurement and with an Andersen sampler to detect viable MRSA. Molecular typing and antimicrobial susceptibility testing were performed on samples collected. Viable MRSA organisms isolated inside the swine facility were primarily associated with particles >5 µm, and those isolated downwind from the swine facility were associated with particles <5 µm. MRSA isolates included spa types t008, t034, and t5706 and were resistant to methicillin, tetracycline, clindamycin, and erythromycin. Animal feed both before and after entry into the swine facility tested positive for viable MRSA. These isolates were of similar spa types as the airborne MRSA organisms. Air samples collected after power washing with a biocide inside the swine facility resulted in no viable MRSA organisms detected. This pilot study showed that the ecology of MRSA is complex. Additional studies are warranted on the maximum distance that viable MRSA can be emitted outside the facility, and the possibility that animal feed may be a source of contamination.

The Endoplasmic Reticulum Stress Sensor Inositol-Requiring Enzyme 1α Augments Bacterial Killing through Sustained Oxidant Production.

ABSTRACTBacterial infection can trigger cellular stress programs, such as the unfolded protein response (UPR), which occurs when misfolded proteins accumulate within the endoplasmic reticulum (ER). Here, we used the human pathogen methicillin-resistant Staphylococcus aureus (MRSA) as an infection model to probe how ER stress promotes antimicrobial function. MRSA infection activated the most highly conserved unfolded protein response sensor, inositol-requiring enzyme 1α (IRE1α), which was necessary for robust bacterial killing in vitro and in vivo. The macrophage IRE1-dependent bactericidal activity required reactive oxygen species (ROS). Viable MRSA cells excluded ROS from the nascent phagosome and strongly triggered IRE1 activation, leading to sustained generation of ROS that were largely Nox2 independent. In contrast, dead MRSA showed early colocalization with ROS but was a poor activator of IRE1 and did not trigger sustained ROS generation. The global ROS stimulated by IRE1 signaling was necessary, but not sufficient, for MRSA killing, which also required the ER resident SNARE Sec22B for accumulation of ROS in the phagosomal compartment. Taken together, these results suggest that IRE1-mediated persistent ROS generation might act as a fail-safe mechanism to kill bacterial pathogens that evade the initial macrophage oxidative burst.

Evaluation of hydrogen peroxide vapor for the inactivation of nosocomial pathogens on porous and nonporous surfaces

Clostridium difficile spores and multidrug-resistant (MDR) organisms, such as methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), and MDR Acinetobacter baumannii, are important nosocomial pathogens that are difficult to eliminate from the hospital environment. We evaluated the efficacy of hydrogen peroxide vapor (HPV), a no-touch automated room decontamination system, for the inactivation of a range of pathogens dried onto hard nonporous and porous surfaces in an operating room (OR). Stainless steel and cotton carriers containing >4 log10 viable MRSA, VRE, or MDR A baumannii were placed at 4 locations in the OR along with 7 pouched 6 log10Geobacillus stearothermophilus spore biologic indicators (BIs). HPV was then used to decontaminate the OR. The experiment was repeated 3 times. HPV inactivated all spore BIs (>6 log10 reduction), and no MRSA, VRE, or MDR A baumannii were recovered from the stainless steel and cotton carriers (>4-5 log10 reduction, depending on the starting inoculum). HPV was equally effective at all carrier locations. We did not identify any difference in efficacy for microbes dried onto stainless steel or cotton surfaces, indicating that HPV may have a role in the decontamination of both porous and nonporous surfaces. HPV is an effective way to decontaminate clinical areas where contamination with bacterial spores and MDR organisms is suspected.

Evaluation of the Filtration Efficiency of the N95 Filtering Facepiece Respirator for Airborne Methicillin-Resistant Staphylococcus aureus

<abstract> <bold><sc>Abstract.</sc></bold> Airborne methicillin-resistant Staphylococcus aureus (MRSA) was detected inside a swine facility that presented a risk of respiratory colonization and infection to swine and swine workers. Viable airborne MRSA was sampled using an Andersen cascade impactor, and total airborne particulates were sampled using an optical particle counter. The filter efficiency of the N95 filtering facepiece respirator (FFR) was evaluated to determine its effectiveness for airborne MRSA. Our study showed that the filter for the N95 FFR had efficiency greater than 95% for airborne MRSA.

Screening for methicillin-resistant Staphylococcus aureus … all doors closed?

To describe the latest evidence for methicillin-resistant Staphylococcus aureus (MRSA) infection control strategies, with particular emphasis on active surveillance cultures with contact precautions and targeted decolonization, and their impact. Several major trials published last year questioned the effectiveness of universal screening and contact precautions in controlling MRSA. These trials generally recommend universal decolonization as part of bundles to control MRSA, especially in ICUs, with some even concluding that universal decolonization should replace active screening and contact precautions. However, emerging resistance to agents used for decolonization, such as mupirocin and chlorhexidine, is a major concern. Several other studies confirmed a combination of hand hygiene enhancement, screening, contact precaution and targeted decolonization as a more viable MRSA infection control strategy for specific population groups. Universal decolonization is an acceptable MRSA control strategy for intensive care units; however, close monitoring of chlorhexidine and mupirocin resistance is warranted. As a strategy, screening and contact precautions are suitable for hospital-wide MRSA control. Targeted decolonization is a proven measure for patients undergoing clean surgery. Enhancement of hand hygiene is a core measure regardless of the strategy.

Survival of Methicillin-Resistant Staphylococcus aureus during Commercial Heat Treatment of Slab Bacon and Consumer Preparation of Sliced Bacon

With the knowledge that retail pork products may be contaminated with methicillin-resistant Staphylococcus aureus (MRSA), the risk of consumers contracting a MRSA infection or foodborne illness from processed meats, especially bacon, is uncertain. Therefore, a study was designed to investigate the survival of MRSA during heat treatment of slab bacon at a commercial process and during cooking of sliced bacon at the consumer level. Fresh pork bellies were injected with a curing solution, inoculated, and heat treated to an internal temperature of 52°C. Three commercial brands of sliced bacon with similar “sell by” dates and fat-to-lean ratios were also inoculated and cooked at a temperature of 177°C for 0, 2, and 5 min on each side. Heat-treated slab bacon showed a log reduction of 1.89, which was significant (P <0.05) compared with an uncooked inoculated control. Cooked sliced bacon had a reduction of viable MRSA cells of >6.5 log CFU/cm2, and there was not a significant brand interaction (P >0.05).

Effect of Oral Administration of β-D-glucan from Aureobasidium pullulans ADK-34 on Candida and MRSA Infections in Immunosuppressed Mice

We examined the effect of the oral administration of β-D-glucan derived from Aureobasidium pullulans ADK-34 (AP-FBG) on Candida albicans or methicillin-resistant Staphylococcus aureus (MRSA) infection in immunosuppressed mice. Mice pretreated with cyclophosphamide (CY) were intraperitoneally administered AP-FBG for 4 days and then infected with 6×10(4) C. albicans cells. In a preliminary experiment, the survival time of the Candida-infected mice treated with AP-FBG was clearly prolonged. Similarly, the effect of the oral administration of AP-FBG was examined. Mice were orally given 2.5% AP-FBG in feed for 42 days from 14 days prior to 2×10(4) C. albicans cells infection. The survival time of mice treated with AP-FBG was significantly prolonged and the viable cell count in the kidneys of the survivors was significantly decreased at 30 days after infection. The effects of the oral administration of AP-FBG on intestinal MRSA infection were also examined. Mice were given 2.5% AP-FBG orally in feed for 30 days before and after oral MRSA infection and treated with CY 12 days after the infection. The number of viable MRSA cells or the IgA production in feces did not significantly change, while AP-FBG administration seemed to relieve temporally the loss of body weight of mice. These results suggest that oral pre-administration of AP-FBG promoted resistance of CY-treated mice to C. albicans and lessened the weight reduction of CY-mice infected by MRSA.

In vitro evaluation of a novel process for reducing bacterial contamination of environmental surfaces

Disinfection of contaminated surfaces is an integral and challenging aspect of infection prevention. We evaluated the ability of Goldshield 5 (GS; NBS Technology, Laurelton, NY), an antimicrobial surfactant that coats surfaces with covalently bound octadecyldimethylammonium ions, to reduce the bacterial burden on contaminated surfaces. We tested the GS product for inhibitory activity against patient isolates of methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa (PA), and Escherichia coli (EC) on fabric according to the garment industry standard American Association of Textile Chemists and Colorists 100 protocol. We also tested the product for activity against these same isolates in carrier tests with a modified Association of Official Analytical Chemists use-dilution method. On fabric, viability of bacterial isolates was inhibited for 14 days. GS also reduced recovery of viable MRSA, PA, and EC from Formica and stainless steel carriers treated with the product. Our results demonstrate that GS has inhibitory activity and potential utility as part of an infection control process.

An Evaluation of Methicillin-ResistantStaphylococcus aureusSurvival on Five Environmental Surfaces

This study evaluated methicillin-resistant Staphylococcus aureus (MRSA) survival on environmental surfaces: glass, wood, vinyl, plastic, and cloth. Effects of relative humidity (RH) and bovine serum albumin (BSA) were examined. Surfaces were inoculated with 10(7)-10(8) colony forming units per milliliter (CFU/ml)of MRSA with and without 1% BSA and incubated at 35°C at 45%-55% and 16% RH. Surfaces were sampled, and each collected sample was re-suspended in phosphate buffer, spread plated, and incubated at 35°C for 24 hrs; resulting colonies were enumerated. Samples were collected immediately on drying, and at 3 hrs, 24 hrs, 2 days, 3 days, 4 days, and 5 days. Results demonstrated that MRSA survived the longest on plastic and vinyl and for the least amount of time on wood (p < 0.001). BSA enabled MRSA to survive for significantly longer duration (p < 0.001). The number of CFU/ml was significantly lesser on surfaces stored in 45%-55% RH versus 16% RH. This study demonstrates that viable MRSA bacteria can remain on surfaces for days, which may impact the public health of occupants in workplace and residential settings.

Efficacy of the new lantibiotic NAI-107 in experimental infections induced by multidrug-resistant Gram-positive pathogens.

NAI-107 is a novel lantibiotic active against Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), glycopeptide-intermediate S. aureus (GISA), and vancomycin-resistant enterococci (VRE). The aim of this study was to evaluate the in vivo efficacy of NAI-107 in animal models of severe infection. In acute lethal infections induced with a penicillin-intermediate Streptococcus pneumoniae strain in immunocompetent mice, or with MRSA, GISA, and VRE strains in neutropenic mice, the 50% effective dose (ED(50)) values of NAI-107 were comparable or lower than those of reference compounds, irrespective of the strain and immune status (0.51 to 14.2 mg/kg of body weight for intravenous [i.v.] NAI-107, 5.1 to 22.4 for oral linezolid, and 22.4 for subcutaneous [s.c.] vancomycin). In the granuloma pouch model induced in rats with a MRSA strain, intravenous NAI-107 showed a dose-proportional bactericidal activity that, at a single 40-mg/kg dose, compared with 2 20-mg/kg doses at a 12-h or 24-h interval, caused a 3-log(10)-CFU/ml reduction of viable MRSA in exudates that persisted for more than 72 h. Rat endocarditis was induced with a MRSA strain and treated for five consecutive days. In a first experiment, using 5, 10, or 20 mg/kg/day, and in a second experiment, when 10 mg/kg at 12-h intervals was compared to 20 mg/kg/day, intravenous NAI-107 was effective in reducing the bacterial load in heart vegetations in a dose-proportional manner. Trough plasma levels, as determined on days 2 and 5, were several times higher than the NAI-107 minimal bactericidal concentration (MBC). NAI-107 binding to rat and human serum ranges between 93% and 98.6%. The rapid bactericidal activity of NAI-107 observed in vitro was thus confirmed by the efficacy in several models of experimental infection induced by Gram-positive pathogens, supporting further investigation of the compound.

Triggering of the Antibacterial Activity of Bacillus subtilis B38 Strain against Methicillin-Resistant Staphylococcus aureus

When cultured in minimal growth medium, the B38 strain of Bacillus subtilis did not exhibit any antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) clinical isolate. Coculturing B38 strain with viable MRSA cells weakly increased antibacterial activity production (20AU/ml). Addition of dead MRSA cells in a B38 culture, increased by 8-fold the B. subtilis strain antibacterial activity reaching 160AU/ml against MRSA strain. This antibacterial activity recovered from cell-free supernatants was stimulated by an autoinducing compound which is sensitive to the action of proteinase K suggesting a proteinaceous nature. This compound was heat-stable till 80°C and showed a molecular mass around 20kDa as determined by SDS-PAGE. These results suggest that the production of antibacterial compounds by B38 strain is dependent on the amount of the autoinducing compound.

In vivo antibacterial and silver‐releasing properties of novel thermal sprayed silver‐containing hydroxyapatite coating

One of the serious postoperative complications associated with joint replacement is bacterial infection. In addressing this problem, we have previously described the development of a novel thermal spraying technology combining silver (Ag) showing antibacterial activity with hydroxyapatite (HA) displaying good biocompatibility and osteoconductivity, and reported the in vitro properties. This study evaluated serum Ag ion concentrations and antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) using a subcutaneous rat model. HA loaded with 3 wt % of silver oxide (Ag-HA) and plain HA were sprayed on the surface of titanium disks. Ag-HA- or HA-coated samples were implanted into the back subcutaneous pockets of male Sprague-Dawley rats. Mean serum Ag ion concentration in the Ag-HA group increased to more than 50 ppb by 48 h after implantation, then decreased gradually to baseline levels. Mean (+/- standard error of the mean) number of viable MRSA on HA coating was (1.5 +/- 0.5) x 10(5), which is significantly more than the (1.1 +/- 0.4) x 10(4) on Ag-HA coating (p < 0.001). Ag-HA coating offers good abilities to release Ag ions and kill MRSA in vivo.

Evaluation of the Copan ESwab transport system for the detection of methicillin-resistant Staphylococcus aureus: a laboratory and clinical study

Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as an important pathogen. Successful detection starts with the selection of an appropriate specimen collection device. The Copan ESwab, a new swab, was compared with a commonly used Copan Venturi swab for the recovery of MRSA. In vitro assessment was performed according to the Clinical and Laboratory Standards Institute (CLSI) M40-A protocol. For the clinical evaluation, 24 patients with known MRSA carriage were included. The ESwab fulfilled the CLSI acceptance criteria for MRSA viability. In the clinical study, both swabs performed equally in qualitative terms of positive and negative. However, the in vitro and in vivo evaluation revealed at least 3.6-fold higher recovery of viable MRSA with the ESwab as compared with the Venturi swab. In conclusion, the ESwab may contribute to improve the quality of a MRSA screening protocol.