Development and characterization of a portable electrochemical aptasensor for IsdA protein and Staphylococcus aureus detection.

Staphylococcus aureus (S. aureus) is recognized as one of the most common causes of gastroenteritis worldwide. This pathogen is a major foodborne pathogen that can cause many different types of various infections, from minor skin infections to lethal blood infectious diseases. Iron-regulated surface determinant protein A (IsdA) is an important protein on the S. aureus surface. It is responsible for iron scavenging via interaction with hemoglobin, haptoglobin, and hemoglobin-haptoglobin complexes. This study develops a portable aptasensor for IsdA and S. aureus detection using aptamer-modified gold nanoparticles (AuNPs) integrated into screen-printed carbon electrodes (SPCEs). The electrode system was made of three parts, including a carbon counter electrode, an AuNPs/carbon working electrode, and a silver reference electrode. The aptamer by Au-S bonding was conjugated on the electrode surface to create the aptasensor platform. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were utilized to investigate the binding interactions between the aptasensor and the IsdA protein. CV studies showed a linear correlation between varying S. aureus concentrations within the range of 101 to 106 CFU/mL, resulting in a limit of detection (LOD) of 0.2 CFU/mL. The results demonstrated strong reproducibility, selectivity, and sensitivity of the aptasensor for enhanced detection of IsdA, along with about 93% performance stability after 30 days. The capability of the aptasensor to directly detect S. aureus via the IsdA surface protein binding was further investigated in a food matrix. Overall, the aptasensor device showed the potential for rapid detection of S. aureus, serving as a robust approach to developing real-time aptasensors to identify an extensive range of targets of foodborne pathogens and beyond.

Self-supporting covalent organic framework membranes synthesized through two different processes: solvothermal annealing and solvent vapor annealing.

Rigid, freestanding covalent organic framework (COF-1) membranes have been synthesized from 1,4-benzenediboronic acid (BDBA) precursors using two different approaches: room temperature solvent-vapour annealing (SVA) and solvothermal annealing (SA). Characterization of films using Fourier-transform infrared (FTIR) spectroscopy, x-ray diffraction (XRD), and various microscopies shows that the films obtained through the two different routes vary in their retained BDBA proportion, crystal size and macroscale morphology. Gas adsorption measurements give specific surface areas of 579 ± 7 m2 g-1 and 739 ± 11 m2 g-1 respectively, suggesting that the average porosity of these films is competitive with bulk-synthesized COF-1 particles. The films have a stratified structure, with a dense, thin top layer and a thicker, sponge-like base layer. Using nanoindentation, we measured the Young's modulus at the top surface of the SVA and SA films to be 3.64 ± 1.20 GPa and 3.33 ± 0.12 GPa respectively, with the smaller uncertainty for the SA film attributed to a more uniform morphology. These measurements provide useful experimental data pertaining to COF-1 mechanical properties, furnishing information relevant to the use of these free-standing membranes in applications such as gas filtration or storage.

Pocket Irrigation and Technique During Reconstructive Surgery: An American Society of Plastic Surgery Survey of Current Practice.

BACKGROUND: Expander-to-implant is the most common breast reconstruction procedure in the United States. Irrigation with triple antibiotic solution (TAS), as described by Adams et al in 2006, has become standard of care to lower bacterial bioburden. However, several alternative solutions have been implemented with the literature lacking a consensus regarding use (Plast Reconstr Surg. 2006;117:30-36). OBJECTIVE: We distributed a peer-reviewed survey among a cohort of American Society of Plastic Surgery (ASPS) members to assess pocket irrigation technique during implant-based reconstructive surgery. We then conducted a pilot in vitro study to determine antibacterial efficacy of the most preferred irrigation at preferred dwell times against select bacterial species linked to breast pocket contamination during reconstructive implant-based surgery. METHODS: The survey was distributed a total of 3 times to a random cohort of 2488 ASPS members in January 2018. During in vitro studies, pure cultures of common breast flora were exposed to TAS versus saline control at 1, 2, and 5 minutes in a simulated in vivo cavity. Viable plate counts were used to assess cell viability. RESULTS: The response rate was above the ASPS survey average at 16% (n = 407). The population reflected a cross-section of practice types and experience levels. Triple antibiotic solution without Betadine was the favored irrigation at 41%, with 73% of its users preferring dwell times of 2 minutes or less. Over 30 distinct breast pocket irrigation solutions were identified. Bacteria added to the in vivo cavity survived a 2-minute dwell time with TAS as follows: 51% Staphylococcus epidermidis, 69% Escherichia coli, 88% Enterococcus faecalis, 88% Pseudomonas aeruginosa, and 98% Acinetobacter baumannii. CONCLUSION: Our survey data demonstrate significant variability in practice and lack of consensus among ASPS members regarding antimicrobial irrigation during reconstructive breast surgery. Our in vitro data underscores the importance of relating clinical practices with laboratory studies of microorganisms potentially linked to breast pocket contamination and suggests that TAS requires either dwell times greater than 5 minutes and/or the inclusion of efficacious antimicrobial agents (eg, Betadine). This finding has the potential to impact antimicrobial pocket irrigation and technique during breast reconstruction.

Bacterial Contamination of Environmental Surfaces of Veterinary Rehabilitation Clinics.

The presence of potentially pathogenic bacteria on veterinary clinic surfaces may be problematic. In this study, we collected swab samples (Fisherbrand, double transport swabs with Stuart's liquid medium) and water samples from five veterinary rehabilitation clinics. Swabs and water samples were transported to a microbiology lab for processing. At the lab, swabs were used to inoculate Hardy's Cdiff Banana Broth (for Clostridium difficile [Cdiff]) and five different types of bacterial growth media, including Hardy CHROM MRSA agar (methicillin-resistant Staphylococcus aureus [MRSA] and S. pseudintermedius [SIM]), mannitol salt agar (S. aureus [SA]), eosin methylene blue agar (enterics [ENT]), Pseudomonas isolation agar (Pseudomonas spp. [PS]), and tryptic soy agar [TSA] (non-specific). The most prominent presumptive species cultured was Cdiff (on nearly 55% of swabs). Bacillus spp. and enteric bacteria were encountered on nearly 35% of swabs, with MRSA and SIM on just over 10% of swabs. The most contaminated sample site was harnesses/life jackets used with the underwater treadmill (33% of swabs). The underwater treadmill water had total bacterial counts from 1,600 to 2,800 cfu/mL. Of all presumptive bacterial species detected, SIM tends to be more pathogenic for dogs. Targeted cleaning/disinfecting in these clinics could help reduce risks for both animals and caregivers utilizing these clinics.

Investigations of Staphylococcal contamination on environmental surfaces of a neonatal intensive care unit of a children's hospital.

Staphylococci species are known to cause healthcare-associated infections in neonatal intensive care (NICU) unit patients. Little is known about Staphylococcal contamination of NICU environments. Swabs from 25 of 46 (54%) surfaces sampled in a NICU had viable Staphylococcal contamination, with 11% contaminated by methicillin resistant Staphylococcus aureus [MRSA]. Floors by sinks and return air ducts in the NICU were the most contaminated (67% positive), possibly serving as reservoirs for Staphylococci.

Infrared and near-infrared spectroscopic study of synthetic hydrotalcites with variable divalent/trivalent cationic ratios.

Near-infrared (NIR), X-ray diffraction (XRD) and infrared (IR) spectroscopy have been applied to hydrotalcites of the formula Mg(6) (Fe,Al)(2)(OH)(16)(CO(3)).4H(2)O formed by intercalation with the carbonate anion as a function of divalent/trivalent cationic ratio. Such hydrotalcites were found to show variation in the d-spacing attributed to the size of the cation. In the IR (1750-4000cm(-1)), the position of all bands except those at approximately 3060cm(-1) shift to higher wavenumbers as the cation ratio increases. Conversely, at wavenumbers below 1000cm(-1), the bands shift to lower wavenumbers as the cation ratio increases. A water bending mode at higher wavenumbers was also observed which indicates that the water is strongly hydrogen bonded. In the NIR spectrum between 8000 and 12,000cm(-1), there is a broad feature which is attributed to electronic bands of the ferrous ion and low intensity sharp bands due to overtones of the OH stretching vibrations. It is also apparent from this region that Fe(2+) substitutes for Mg(2+). The intensity of bands at 7750 and 5200cm(-1) increases as the cation ratio increases in the NIR spectrum. Hydrotalcites with a magnesium amount 3 and 4 times greater than that of aluminium and iron combined, in the lower wavenumber region of the NIR spectrum, have very similar spectral profiles. This work has shown that hydrotalcites with different divalent/trivalent ratios can be synthesised and characterised by infrared spectroscopy.

Topical lotions utilized in outpatient rehabilitation clinics as a potential source of bacterial contamination.

Soft tissue mobilization and massage requiring lotions or creams are commonly used interventions in outpatient rehabilitation clinics. For at least 50 years hand creams used in healthcare settings have been found to be contaminated by bacteria. The purpose of this study was to determine the current state of bacterial contamination of lotions used in clinics and to determine the efficacy of lotion preservatives to kill bacteria. Unopened containers of lotions were studied, along with 81 lotion containers used in 22 outpatient clinics in southeast Tennessee and northwest Georgia. Three sites on each container were sampled using sterile swabs. At a microbiology lab, bacterial growth media was inoculated and incubated. Of the 81 containers sampled, 16 supported bacterial growth (19.8%). Container threads displayed the highest contamination compared with other container locations (p < 0.01). No bacteria were found in unopened lotion containers, although when challenged with live bacterial cultures lotion preservatives did not kill bacteria tested. Enrichment cultures using lotions studied here supported the growth of several bacterial species. These findings suggest the need for standardized protocols to help reduce potential healthcare-associated infections due to use of lotions. Improved efficacy of preservatives added to lotions should be a priority.

Survival of Staphylococcus aureus on therapeutic ultrasound heads.

Therapeutic ultrasound (US) is commonly used in the rehabilitation of soft tissue injuries including wounds. US heads and coupling gel come into direct contact with patient skin, increasing the risk for health care-associated infections owing to cross contamination. In this study, nearly 80% of Staphylococcus aureus placed on US heads in gel survived for 1 hour, with survival of 3 days possible in other types of organic matter.

Physical therapy clinic therapeutic ultrasound equipment as a source for bacterial contamination.

A procedure commonly used in physical therapy (PT) clinics is therapeutic ultrasound (US). This equipment and associated gel comes in contact with patient skin, potentially serving as a reservoir for bacteria. In this study, we sampled US heads, gel bottle tips and gel from nine outpatient PT clinics in Southeastern Tennessee. Samples were collected using sterile swabs. At the microbiology laboratory, these swabs were used to inoculate mannitol salt agar and CHROM-MRSA agar (for Staphylococcal species) and tryptic soy broth to determine non-specific bacterial contamination. US heads, gel bottle tips and gel had variable levels of contamination. Tips of gel bottles had the highest contamination, with 52.7% positive for non-specific bacterial contamination and 3.6% positive for methicillin-resistant Staphylococcus aureus (MRSA). Contamination of gel by non-specific bacteria was found in 14.5% of bottles sampled. US heads (35.5% of those sampled) had non-specific bacterial contamination, with no MRSA detected. Disinfecting US heads after initial swabbing resulted in removal of 90.9% of non-specific contamination. Gel storage at temperatures below 40 °C was found to encourage the growth of mesophilic bacteria. This study demonstrates the need for better cleaning and storage protocols for US heads and gel bottles in PT clinics.