A microbiological survey approach to understanding the virulence factors of Pseudomonas species in healthcare sinks.

BACKGROUND: Hospital water is involved in both the prevention and spread of healthcare-associated infections (HCAIs). Handwashing is key to reducing the transmission of pathogens, yet numerous outbreaks have been found to be caused by organisms within sinks, taps and showers. Pseudomonas aeruginosa and increasingly non-aeruginosa Pseudomonas cause waterborne HCAI, however, little is known about the virulence potential of Pseudomonas species found within hospital environments. METHODS: Swabs were taken from 62 sinks within two newly opened wards at Great Ormond Street Hospital, samples were taken before and after the wards opened to understand the impact of patient occupancy on sink micro-organisms. Culturable bacteria were identified by MALDI-TOF and virulence factors assessed through phenotypic methods. RESULTS: A total of 106 bacterial isolates were recovered including 24 Pseudomonas isolates. Of these 25% were identified as P. oleovorans, 21% P. aeruginosa, 17% P. composti, 13% P. alicalipha, 8% P. monteilii, 4% P. putida, 4% P. stutzeri and 8% could only be identified to genus level by MALDI-TOF. Differences were seen in both the number of Pseudomonas isolates and virulence production between the two wards, overall 25% of the Pseudomonas isolates produced pigment, 58% were capable of haemolysis, 87.5% were able to swim, 83.3% were capable of twitching motility, 33.3% produced alkaline protease and 8.3% produced gelatinase. CONCLUSIONS: Results suggest that patients may be back-contaminating sinks with colonizing organisms which has ongoing implications for infection prevention and control. Additionally, this work highlights the ability of non-aeruginosa Pseudomonas to produce virulence factors traditionally associated with P. aeruginosa.

Trends in viable microbial bioburden on surfaces within a paediatric bone marrow transplant unit.

BACKGROUND: Despite their role being historically overlooked, environmental surfaces have been shown to play a key role in the transmission of pathogens causative of healthcare-associated infection. To guide infection prevention and control (IPC) interventions and inform clinical risk assessments, more needs to be known about microbial surface bioburdens. AIM: To identify the trends in culturable bacterial contamination across communal touch sites over time in a hospital setting. METHODS: Swab samples were collected over nine weeks from 22 communal touch sites in a paediatric bone marrow transplant unit. Samples were cultured on Columbia blood agar and aerobic colony counts (ACC) per 100 cm2 were established for each site. Individual colony morphologies were grouped and identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry or 16s rDNA sequencing. FINDINGS: Highest mean counts were observed for sites associated with ward management activity and computer devices (3.29 and 2.97 ACC/100 cm2 respectively). A nurses' station keyboard had high mean ACC/100 cm2 counts (10.67) and diversity, while laundry controls had high mean ACC/100 cm2 counts (4.70) and low diversity. Micrococcus luteus was identified in all sampling groups. Clinical staff usage sites were contaminated with similar proportions of skin and environmental flora (52.19-46.59% respectively), but sites associated with parental activities were predominantly contaminated by environmental microflora (86.53%). CONCLUSION: The trends observed suggest patterns in microbial loading based on site activities, surface types and user groups. Improved understanding of environmental surface contamination could help support results interpretation and IPC interventions, improving patient safety.

Synergistic Antibacterial Effects of Metallic Nanoparticle Combinations.

Metallic nanoparticles have unique antimicrobial properties that make them suitable for use within medical and pharmaceutical devices to prevent the spread of infection in healthcare. The use of nanoparticles in healthcare is on the increase with silver being used in many devices. However, not all metallic nanoparticles can target and kill all disease-causing bacteria. To overcome this, a combination of several different metallic nanoparticles were used in this study to compare effects of multiple metallic nanoparticles when in combination than when used singly, as single elemental nanoparticles (SENPs), against two common hospital acquired pathogens (Staphylococcus aureus and Pseudomonas. aeruginosa). Flow cytometry LIVE/DEAD assay was used to determine rates of cell death within a bacterial population when exposed to the nanoparticles. Results were analysed using linear models to compare effectiveness of three different metallic nanoparticles, tungsten carbide (WC), silver (Ag) and copper (Cu), in combination and separately. Results show that when the nanoparticles are placed in combination (NPCs), antimicrobial effects significantly increase than when compared with SENPs (P < 0.01). This study demonstrates that certain metallic nanoparticles can be used in combination to improve the antimicrobial efficiency in destroying morphologically distinct pathogens within the healthcare and pharmaceutical industry.

How to carry out microbiological sampling of healthcare environment surfaces? A review of current evidence.

There is increasing evidence that the hospital surface environment contributes to the spread of pathogens. However, evidence on how best to sample these surfaces is inconsistent and there is no guidance or legislation in place on how to do this. The aim of this review was to assess current literature on surface sampling methodologies, including the devices used, processing methods, and the environmental and biological factors that might influence results. Studies published prior to March 2019 were selected using relevant keywords from ScienceDirect, Web of Science, and PubMed. Abstracts were reviewed and all data-based studies in peer-reviewed journals in the English language were included. Microbiological air and water sampling in the hospital environment were not included. Although the numbers of cells or virions recovered from hospital surface environments were generally low, the majority of surfaces sampled were microbiologically contaminated. Of the organisms detected, multidrug-resistant organisms and clinically significant pathogens were frequently isolated and could, therefore, present a risk to vulnerable patients. Great variation was found between methods and the available data were incomplete and incomparable. Available literature on sampling methods demonstrated deficits with potential improvements for future research. Many of the studies included in the review were laboratory-based and not undertaken in the real hospital environment where sampling recoveries could be affected by the many variables present in a clinical environment. It was therefore difficult to draw overall conclusions; however, some recommendations for the design of routine protocols for surface sampling of healthcare environments can be made.

Gyrospun antimicrobial nanoparticle loaded fibrous polymeric filters.

A one step approach to prepare hybrid nanoparticle embedded polymer fibres using pressurised gyration is presented. Two types of novel antimicrobial nanoparticles and poly(methylmethacrylate) polymer were used in this work. X-ray diffraction analysis of the nanoparticles revealed Ag, Cu and W are the main elements present in them. The concentration of the polymer solution and the nanoparticle concentration had a significant influence on the fibre diameter, pore size and morphology. Fibres with a diameter in the range of 6-20µm were spun using 20wt% polymer solutions containing 0.1, 0.25 and 0.5 wt% nanoparticles under 0.3MPa working pressure and a rotational speed of 36,000rpm. Continuous, bead-free fibre morphologies were obtained for each case. The pore size in the fibres varied between 36 and 300nm. Successful incorporation of the nanoparticles in polymer fibres was confirmed by energy dispersive x-ray analysis. The fibres were also gyrospun on to metallic discs to prepare filters which were tested for their antibacterial activity on a suspension of Pseudomonas aeruginosa. Nanoparticle loaded fibres showed higher antibacterial efficacy than pure poly(methylmethacrylate) fibres.

Evaluation of plant and fungal extracts for their potential antigingivitis and anticaries activity.

The link between diet and health has lead to the promotion of functional foods which can enhance health. In this study, the oral health benefits of a number of food homogenates and high molecular mass and low molecular mass fractions were investigated. A comprehensive range of assays were performed to assess the action of these foods on the development of gingivitis and caries using bacterial species associated with these diseases. Both antigingivitis and anticaries effects were investigated by assays examining the prevention of biofilm formation and coaggregation, disruption of preexisting biofilms, and the foods' antibacterial effects. Assays investigating interactions with gingival epithelial cells and cytokine production were carried out to assess the foods' anti- gingivitis properties. Anti-caries properties such as interactions with hydroxyapatite, disruption of signal transduction, and the inhibition of acid production were investigated. The mushroom and chicory homogenates and low molecular mass fractions show promise as anti-caries and anti-gingivitis agents, and further testing and clinical trials will need to be performed to evaluate their true effectiveness in humans.

Spectrophotometric determination of diltiazem in dosage forms.

A simple and reproducible method for determination of diltiazem in bulk and in dosage forms is presented. The method is based on formation of hydroxamic acid, which reacts with iron (III), forming a complex with a maximum absorption at 525 nm. Assay procedure for diltiazem dosage form requires thin-layer chromatographic separation prior to colorimetric analysis.