Factors influencing environmental sampling recovery of healthcare pathogens from non-porous surfaces with cellulose sponges

Results from sampling healthcare surfaces for pathogens are difficult to interpret without understanding the factors that influence pathogen detection. We investigated the recovery of four healthcare-associated pathogens from three common surface materials, and how a body fluid simulant (artificial test soil, ATS), deposition method, and contamination levels influence the percent of organisms recovered (%R). Known quantities of carbapenemase-producing KPC+ Klebsiella pneumoniae (KPC), Acinetobacter baumannii, vancomycin-resistant Enterococcus faecalis, and Clostridioides difficile spores (CD) were suspended in Butterfield’s buffer or ATS, deposited on 323cm2 steel, plastic, and laminate surfaces, allowed to dry 1h, then sampled with a cellulose sponge wipe. Bacteria were eluted, cultured, CFU counted and %R determined relative to the inoculum. The %R varied by organism, from <1% (KPC) to almost 60% (CD) and was more dependent upon the organism’s characteristics and presence of ATS than on surface type. KPC persistence as determined by culture also declined by >1 log10 within the 60 min drying time. For all organisms, the %R was significantly greater if suspended in ATS than if suspended in Butterfield’s buffer (p<0.05), and for most organisms the %R was not significantly different when sampled from any of the three surfaces. Organisms deposited in multiple droplets were recovered at equal or higher %R than if spread evenly on the surface. This work assists in interpreting data collected while investigating a healthcare infection outbreak or while conducting infection intervention studies.

Method-Related Impacts on Campylobacter coli Recovery From Sampling Materials And Meat

A defined Campylobacter coli (C. coli) suspension was inoculated on sterile sampling materials (cotton bud, polyester bud, cellulose sponge) and pieces of lamb meat. Various combinations of diluents (phosphate buffer saline ± Tween®80) and sampling methods (direct homogenization, simulating the excision method for meat, and swabbing) were investigated for the recovery (detachment) of C. coli cells from the inoculated samples. The obtained C. coli bacteria, as quantified by real-time PCR with respect to the dilution factors and the initial inoculum, were used for the calculation of the recovery (%) per sampling material and method. Regarding artificially inoculated sampling materials, the lowest recovery was observed for cotton buds (2.8%) and the highest for cellulose sponge (28.9%), and the differences between the obtained results were statistically significant (P < 0.05). As regards lamb meat, the lowest recovery was observed for swabbing with cotton buds (3.2%) and the highest for direct homogenization (10.7%). The results indicate an overall low rate of bacterial recovery from contaminated samples, with cellulose sponges and polyester buds being significantly superior to cotton buds, and direct homogenization of meat with diluent better than swabbing. The type of sampling materials and methods applied for the quantification of C. coli entails a key impact on determining the actual contamination of the examined samples.

Mineralization of phosphorylated cellulose/ sodium alginate sponges as biomaterials for bone tissue engineering

In recent years cellulose sponge is attractive for bone tissue materials in tissue engineering, however cellulose with hydroxyl groups shows weak apatite nucleation ability in simulated body fluid (SBF). In...

Fabrication of Cellulose Sponge: Effects of Drying Process and Cellulose Nanofiber Deposition on the Physical Strength

Cellulose sponge was fabricated by regenerating cellulose from a xanthate solution. The solution, which contained sodium phosphate particles as a template to create sponge porosity, was dried at 55, 65, 75 and 85 °C for 2, 4, 6, and 8 h. Mass transfer during the initial and last stages of drying was controlled in terms of temperature and concentration differences, respectively. The activation energy and pre-exponential factor of the mass transfer coefficient were -51,841.947 kJ mol-1 and 7.26×109 m-2 h-1, respectively. Regenerated cellulose contained a crystalline type of cellulose II, and the crystallinity was independent of drying conditions. At a low drying temperature (T≤55 °C) and short drying period (t≤2h), the cellulose was unregenerated. At higher temperatures and longer drying periods, no relationship between temperature and physical strength was observed. Cellulose nanofiber (CNF) was added to the xanthate solution at a ratio of 1:100 of CNF to linter cellulose for xanthation; however, this did not affect the physical strength of the cellulose sponge for both mechanically and chemically fabricated CNF.