Bioburden detection on surface and water samples in a rapid, ultra-sensitive and high-throughput manner

Bioburden detection is crucial for food, water, and biopharmaceutical applications as it can directly impact public health. The objective of this study is to develop and validate an assay and protocol for detecting bioburden on solid surfaces, as well as in water, with high sensitivity and accuracy in a rapid manner. Henceforth, a resazurin-based assay optimized for detecting bioburden has been integrated with a previously developed portable multichannel fluorometer. The microbes were isolated from solid surfaces in different laboratory settings by swabbing technique, and stream water was collected for contamination analysis. Based on the results, the assay and protocol can successfully detect bioburden as low as 20 CFU/cm2 and 10 CFU/mL present in both surface and water samples, respectively.

In vitro and in vivo evaluation of the antimicrobial effectiveness of non-medicated hydrophobic wound dressings

There is an increasing use of non-medicated wound dressing with claims of irreversible bacterial binding. Most of the data are from in vitro models which lack clinical relevance. This study employed a range of in vitro experiments to address this gap and we complemented our experimental designs with in vivo observations using dressings obtained from patients with diabetes-related foot ulcers. A hydrophobic wound dressing was compared with a control silicone dressing in vitro. Test dressings were placed on top of a Pseudomonas aeruginosa challenge suspension with increasing concentrations of suspension inoculum in addition to supplementation with phosphate buffered saline (PBS) or increased protein content (IPC). Next, we used the challenge suspensions obtained at the end of the first experiment, where bacterial loads from the suspensions were enumerated following test dressing exposure. Further, the time-dependent bacterial attachment was investigated over 1 and 24 h. Lastly, test dressings were exposed to a challenge suspension with IPC, with or without the addition of the bacteriostatic agent Deferiprone to assess the impacts of limiting bacterial growth in the experimental design. Lastly, two different wound dressings with claims of bacterial binding were obtained from patients with chronic diabetes-related foot ulcers after 72 h of application and observed using scanning electron microscope (SEM). Bacteria were enumerated from each dressing after a 1-h exposure time. There was no statistical difference in bacterial attachment between both test dressings when using different suspension inoculum concentrations or test mediums. Bacterial attachment to the two test dressings was significantly lower (p < 0.0001) when IPC was used instead of PBS. In the challenge suspension with PBS, only the hydrophobic dressing achieved a statistically significant reduction in bacterial loads (0.5 ± 0.05 log colony forming units; p = 0.001). In the presence of IPC, there was no significant reduction in bacterial loads for either test dressing. When bacterial growth was arrested, attachment to the test dressings did not increase over time, suggesting that the number of bacteria on the test dressings increases over time due to bacterial growth. SEM identified widespread adsorption of host fouling across the test dressings which occurred prior to microbial binding. Therein, microbial attachment occurred predominantly to host fouling and not directly to the dressings. Bacterial binding is not unique to dialkylcarbamoyl chloride (DACC) dressings and under clinically relevant in vitro conditions and in vivo observations, we demonstrate (in addition to previously published work) that the bacterial binding capabilities are not effective at reducing the number of bacteria in laboratory models or human wounds.

Radiation processing of bacterial cellulose-monolaurin wound dressing: Physicochemical effects, functional analysis, and sterilization

A commercial bacterial cellulose-monolaurin wound dressing was investigated for changes in the chemical structure, mechanical strength, thermal degradation, morphology, and functional swelling properties after exposure to gamma and electron beam radiations at doses 15-50 kGy. Radiation-induced oxidation occurred as seen in the FT-IR peaks at 1720-1750 cm-1. Degradation of the cellulosic network was observed in tensile strength reduction and shift in degradation temperature to lower values. The SEM cross-section images of the irradiated dressings revealed a less dense nanostructure network compared to the non-irradiated samples while the XRD diffractograms indicated a change in lattice direction/plane. Despite these changes, irradiation caused no significant effect on the functional properties especially at 15-25 kGy doses where most biomedical devices are sterilized. All irradiated wound dressings exhibited physical integrity, increased exudate absorption, and water vapor transmission rate - properties beneficial to wound-healing functionality. The pre-selected sterilization dose of 15 kGy for each ionizing radiation was successfully verified and substantiated following ISO 11137-2:2016, hence ionizing radiation is a suitable sterilization modality for the product.

Modeling of recovery efficiency of sampling devices used in planetary protection bioburden estimation

IMPORTANCE

Planetary protection at the National Aeronautics and Space Administration (NASA) requires bioburden on certain spacecraft to be estimated via sampling in order to comply with biological cleanliness requirements. To achieve this, the recovery efficiency of devices used to sample the spacecraft pre-launch must be understood and their uncertainty quantified in order to produce the most reasonable estimates of bioburden. This study brings together experiments performed by NASA and the European Space Agency with approved swab and wipe sampling devices, inoculating steel coupons with laboratory strains of Bacillus spp. spores commonly recovered from spacecraft assembly clean rooms (B. atrophaeus, B. megaterium, B. safensis and B. thuringiensis), with a mathematical model of the assay process to assess recovery efficiency. The statistical treatment developed in this study allows comparison of bioburden estimates made from different devices processed by different methods. This study also gives stakeholders and practitioners a statistically rigorous approach to predict bioburden that can be folded into future modeling efforts.

Assessment of microbial contamination in laser materials processing laboratories used for prototyping of biomedical devices

Microbial contamination of medical devices during pilot production can be a significant barrier as the laboratory environment is a source of contamination. There is limited information on microbial contaminants in laser laboratories and environments involved in the pilot production of medical devices. This study aimed to determine the bioburden and microbial contaminants present in three laser laboratories - an ISO class 7 clean room, a pilot line facility and a standard laser laboratory. Microbiological air sampling was by passive air sampling using settle plates and the identity of isolates was confirmed by DNA sequencing. Particulate matter was analysed using a portable optical particle counter. Twenty bacterial and 16 fungal genera were isolated, with the genera Staphylococcus and Micrococcus being predominant. Most isolates are associated with skin, mouth, or upper respiratory tract. There was no significant correlation between microbial count and PM2.5 concentration in the three laboratories. There were low levels but diverse microbial population in the laser-processing environments. Pathogenic bacteria such as Acinetobacter baumannii and Candida parapsilosis were isolated in those environments. These results provide data that will be useful for developing a contamination control plan for controlling microbial contamination and facilitating advanced manufacturing of laser-based pilot production of medical devices.

Assessing the impact of sanitization methods for regenerated cellulose ultrafiltration/diafiltration membrane on membrane integrity and protein quality

Ultrafiltration/diafiltration (UF/DF) is typically the final step in downstream processing of recombinant monoclonal antibody (mAb) products, which serves for protein concentration and buffer exchange. For UF/DF membranes composed of regenerated cellulose (RC), sanitization with 0.1 M sodium hydroxide is generally recommended by the supplier, but it may not be sufficient for reducing bioburden during large scale manufacturing. Therefore, more stringent sanitization methods for RC membranes are required. However, chemicals used in such sanitization step may disrupt membrane integrity, while the corresponding residuals may reduce product quality. Previous work has shown that high concentration of sodium hydroxide or addition of peracetic acid (PAA) can effectively reduce bioburden, but their effects on the RC membranes remain unknown. In this work, we assessed the impact of two sanitization methods, 0.5 M sodium hydroxide and 30 mM PAA in combination with 0.5 M sodium hydroxide, on membrane integrity and protein quality of Millipore and pall corporation (PALL) membranes. Both methods showed a similar impact as the control after performing 15 cycles. However, the addition of PAA may cause residual chemical concerns, therefore, 0.5 M sodium hydroxide was recommended as an effective and safe sanitization method for RC UF/DF membranes.

Five-year trends in bacterial contamination of dialysis equipment

Bedside dialysis monitoring equipment for hemodialysis are located in the bioburden section upstream of the endotoxin-retentive filter for dialysis fluid sterilization. We observed 26 equipment at our institution for bacterial contamination at least once every 4 weeks for 5 years with another ultrafiltration membrane upstream to prevent bacterial contamination. Bacterial contamination levels were highest and most diverse at the time of the first flush. During subsequent initial cleanng, the contamination level decreased, and bacterial species converged almost exclusively to one genus, namely Methylobacterium spp. During clinical use, the equipment were cleaned and disinfected daily after dialysis, and daily operations and maintenance were performed using aseptic techniques. Although the frequency of bacterial detection decreased annually, the same bacterial genotypes observed at the first flush were isolated even after long time periods and were thought to persist in the equipment possibly by forming biofilm. Pseudomonas aeruginosa was newly detected after the replacement of parts during breakdown maintenance, indicating the need to sterilize replacement parts. Thus, the bioburden should be assessed regularly as part of the management of in-house-produced dialysis fluid.

Bioburden Variation of Filtering Face Piece Respirators over Time: A Preliminary Study

BACKGROUND

The microbial contamination of a respirator can be evaluated through a count of the number of bacteria living on a non-sterilized surface (bioburden). This preliminary study investigated the external contamination of two different FFP2s over time by studying the bioburden values in increasing exposure times.

METHODS

FFP2 respirators of two different brands were used during routine clinical settings and examined through the bioburden test; for each brand, three devices were tested at 8, 16, and 30 h.

RESULTS

No significant differences were observed between mask brands (p = 0.113). There were only significant CFU differences between each mask and its control (p = 0.027 and p = 0.004).

CONCLUSIONS

Both brands of respirators were found to be contaminated and this contamination increased with the increase in exposure time. Further studies are needed to investigate the exact amount of contamination that could be considered acceptable before discarding each used mask.

Significant and rapid reduction of free endotoxin using a dialkylcarbamoyl chloride-coated wound dressing

OBJECTIVE

Endotoxin causes inflammation and can impair wound healing. Conventional methods that reduce bioburden in wounds by killing microorganisms using antibiotics, topical antimicrobials or antimicrobial dressings may induce endotoxin release from Gram-negative bacteria. Another approach is to reduce bioburden by adsorbing microorganisms, without killing them, using dialkylcarbamoyl chloride (DACC)-coated wound dressings. This study evaluated the endotoxin-binding ability of a DACC-coated wound dressing (Sorbact Compress, Abigo Medical AB, Sweden) in vitro, including its effect on the level of natural endotoxin released from Gram-negative bacteria.

METHOD

Different concentrations of purified Pseudomonas aeruginosa endotoxin and a DACC-coated dressing were incubated at 37°C for various durations. After incubation, the dressing was removed and endotoxin concentration in the solution was quantified using a Limulus amebocyte lysate (LAL) assay. The DACC-coated dressing was also incubated with Pseudomonas aeruginosa cells for one hour at 37°C. After incubation, the dressing and bacterial cells were removed and shed endotoxin remaining in the solution was quantified.

RESULTS

Overnight incubation of the DACC-coated wound dressing with various concentrations of purified Pseudomonas aeruginosa endotoxin (96-11000 EU/ml) consistently and significantly reduced levels of free endotoxin by 93-99% (p<0.0001). A significant endotoxin reduction of 39% (p<0.001) was observed after five minutes. The DACC-coated dressing incubated with clinically relevant Pseudomonas aeruginosa cells also reduced shed endotoxin by >99.95% (p<0.0001).

CONCLUSION

In this study, we showed that a DACC-coated wound dressing efficiently and rapidly binds both purified and shed endotoxin from Pseudomonas aeruginosa in vitro. This ability to remove both endotoxin and bacterial cells could promote the wound healing process.

Bioburden on Imaging Lead Apparel and Infection Control Measures

PURPOSE

To explore the level of bioburden and the effectiveness of the manufacturers' recommended cleaning methods on lead apparel in a radiology department.

METHODS

A 2-phase experiment at a level II trauma center during a 2-year period assessed the level of bioburden on radiology lead apparel. Adenosine triphosphate swabs and a luminometer were used to measure cleanliness of high-touch areas. Cleanliness was measured before and after 3 cleaning methods were used: cleaning with a mild detergent and water; cleaning with a mild detergent, water, and then a disinfectant; and scrubbing with cleaning wipes.

RESULTS

Average bioburden levels exceeded facility thresholds for all areas and types of lead apparel examined. All tested cleaning methods significantly reduced bioburden.

DISCUSSION

Monthly cleaning of lead apparel provides improved cleanliness when compared with quarterly cleaning. Daily cleaning of lead apparel that will be used in a sterile environment is recommended. Future research might include examining other patient care and ancillary equipment found in the imaging department for potential bioburden and surveying technologists to examine practices for routine removal of bioburden from equipment.

CONCLUSION

Health care professionals must be aware of the potential bioburden on clinical equipment and maintain an effective cleaning practice and schedule to reduce the possibility of spreading infection.

Settled dust assessment in clinical environment: useful for the evaluation of a wider bioburden spectrum

The collection and analysis of settled dust samples from indoor environments has become one of several environmental sampling methods used to assess bioburden indoors. The aim of the study was to characterize the bioburden in vacuumed settled dust from 10 Primary Health Care Centers by culture based and molecular methods. Results for bacterial load ranged from 1 to 12 CFU.g^-1 of dust and Gram-negative bacteria ranged between 1 to 344 CFU.g^-1 of dust. Fungal load ranged from 0 CFU.g^-1 of dust to uncountable. Aspergillus section Fumigati was detected in 4 sampling sites where culture base-methods could not identify this section. Mucorales (Rhizopus sp.) was observed on 1 mg/L voriconazole. Three out of 10 settled dust samples were contaminated by mycotoxins. Settled dust sampling coupled with air sampling in a routine way might provide useful information about bioburden exposure.

In vitro evaluation of bioburden, three-dimensional stability, and accuracy of surgical templates without metallic sleeves after routinely infection control activities

BACKGROUND

Surgical templates are classified as noncritical devices, and they do not need to be sterile.

AIM

Primary aim of this study was to assess the microbiological burden present on the surgical templates without metallic sleeves after disinfection. Furthermore, to evaluate trueness after disinfection and steam sterilization at 121°C/15 min, and over a 8-week storage period. Finally, to assess their accuracy after in vitro implant placement simulation.

MATERIALS AND METHODS

Forty surgical templates were printed and divided in five groups of eight templates each. Groups A to C were disinfected with 0.5% Chlorhexidine Gluconate and 70% ethyl alcohol base solution for 15 min. Templates in the group D were steam sterilized at 121°C for 15 min, while, the templates in the group E were used as control. Implant simulation was performed in the group A. Outcome measures were determination of bioburden, trueness assessment using GOM Inspect Professional software, and accuracy evaluated thought the mean angular deviation of simulated implants.

RESULTS

Total microbic charge measured as colony forming units (CFU) for sample, was 24.40 in the control group (group E; n = 8), and <4.40 in the test group (group C; n = 8), with a reduction of 84%. Colored representation from GOM inspection showed no differences after disinfection and implant simulation, disinfection alone, and steam sterilization, compared to the control group. A very small difference in the surface and volume dimensions was reported 1 month after templates fabrication. The mean roundness tolerances of the tested templates improved of 0.96 ± 0.56° (95% CI 0.57-1.35).

CONCLUSION

Surgical templates without metallic sleeves can be safely used after disinfection, demonstrating high level of accuracy, even when the surgical procedures should be postponed within a couple of weeks. Further in vivo study are needed to confirm these preliminary results.

Settleable Dust and Bioburden in Portuguese Dwellings

Monitoring campaigns in several buildings have shown that occupants exposed to contaminated indoor air generally exhibit diverse health symptoms. This study intends to assess settleable dust loading rates and bioburden in Portuguese dwellings by passive sampling onto quartz fiber filters and electrostatic dust cloths (EDCs), respectively. Settled dust collected by EDCs was analyzed by culture-based methods (including azole-resistance screening) and qPCR, targeting four different toxigenic Aspergillus sections (Flavi, Fumigati, Circumdati, and Nidulantes). Dust loading rates and bioburden showed higher variability in the summer season. In both seasons, Penicillium sp. was the one with the highest prevalence (59.1% winter; 58.1% summer), followed by Aspergillus sp. in winter (13.0%). Fungal contamination increased in the winter period, while bacterial counts decreased. Aspergillus sections Circumdati and Nidulantes, detected in voriconazole supplemented media, and Aspergillus sections Fumigati and Nidulantes, detected by molecular tools, were found in the winter samples. This study reinforces the importance of applying: (a) Passive sampling methods in campaigns in dwellings; (b) two different culture media (MEA and DG18) to assess fungi; (c) in parallel, molecular tools targeting the most suitable indicators of fungal contamination; and (d) azole resistance screening to unveil azole resistance detection in fungal species.

Adenosine Triphosphate-Bioluminescence Technology as an Adjunct Tool to Validate Cleanliness of Surgical Instruments

Perioperative and sterile processing department personnel commonly use visual inspection to validate surgical instrument cleanliness. This validation process does not detect microbes (eg, bacteria, viruses) and the resultant inadequately decontaminated instruments can put patients at risk for developing surgical site infections. Sterile processing department personnel should use a rapid, straightforward method to validate surgical instrument cleanliness objectively. During a quality improvement project at a military treatment facility, staff members found that adenosine triphosphate (ATP)-based technology was a viable and affordable solution for detecting bioburden and validating cleaning practices. The project design compared manually and mechanically cleaned cannulated instruments (59 of each) and identified 16 contaminated instruments, 14 of which had been manually cleaned. The contamination rate after mechanical cleaning was significantly lower (P = .0022) compared with manual cleaning. As a result of this quality improvement project, this facility fully implemented the technology to validate instrument cleaning.

Radioprotection and cross-linking of allograft bone in the presence of vitamin E

Bone allografts are the preferred method for bone augmentation in over 500,000 orthopedic surgical procedures in the US. Sterilization by ionizing radiation is the most effective method of minimizing the bioburden of bone allografts; however, radiation causes chain scission of collagen, resulting in the reduction of the allografts' mechanical strength. In this study, we doped bone allografts with vitamin E as radioprotectant using a novel two-step process to protect the collagen architecture against radiation damage and to preserve the mechanical strength of the construct. In addition, combining the radioprotectant with a cross-linking agent further minimized collagen degradation and further preserved the mechanical strength of the allografts. Both vitamin E and combined vitamin E/genipin-treated allograft were less cytotoxic to both osteoblasts and osteoclasts when compared to irradiated-only allografts. Host bone-allograft unionization was faster in a rat calvaria defect model with vitamin E-treated and combined vitamin E and genipin-treated allograft when compare to irradiated-only allografts. This method can enable the efficient and uniform radioprotective treatment of bone allograft of desired shapes for sterilization with improved mechanical strength and biointegration.

Updates on Evidence-Based Practices to Reduce Preoperative and Intraoperative Contamination of Implants in Spine Surgery: A Narrative Review

The current communication seeks to provide an updated narrative review on latest methods of reducing implant contaminations used during spine surgery. Recent literature review has shown that both preoperative reprocessing and intraoperative handling of implants seem to contaminate implants. In brief, during preoperative phase, the implants undergo repeated bulk cleaning with dirty instruments from the OR, leading to residue buildup at the interfaces and possibly on the surfaces too. This, due to its concealed nature, remains unnoticed by the SPD (sterile processing department) or other hospital staff. Nevertheless, these can be avoided by using individually prepackaged presterilized implants. In the intraoperative phase, the implants (in the sterile field) are directly touched by the scrub tech with soiled (assisting the surgeon dispose the tissues from the instruments in use) gloves for loading onto an insertion device. It is then kept exposed on the working table (either separately or next to the used instruments as the pedicles hole are being prepared). Latest investigation has shown that by the time it is implanted in the patient, it can harbor up to 10e7 bacterial colony-forming units. The same implants were devoid of such colony-forming units, when sheathed by an impermeable sterile sheath around the sterile implant.

Understanding the factors involved in determining the bioburdens of surgical masks

Background

Surgical site infection (SSI) continues to be one of the most common postoperative complications. In our previous study, surgical mask (SM) bioburden was identified to be a potential source of SSI. In the present study, we investigated the factors involved in SM bioburden.

Methods

Bioburdens of the disposable SM (A: medical mask; B: medical surgical mask) and newly laundered cloth SM (C) were tested by immediately making an impression of the external surface of the mask on sterile culture media. SM microstructure was observed using a scanning electron microscope (SEM). Filtering efficiency and airflow resistance were evaluated with TSI Automated Filter Tester 8130 (TSI Incorporated) according to GB/19083-2010. Whether speaking during operation and washing the face pre-operatively affect SM bioburdens was also evaluated. Surgical procedures were performed in a dynamic operation room. Fifty cases of mask use were enrolled in this study.

Results

The bioburden of mask A was the highest. The bioburden of mask B was the lowest. Mask C possessed the lowest filtering efficiency and the highest airflow resistance. SM bioburden was higher in the speaking group. SM bioburden showed no significant difference after washing the face, despite the finding that washing could significantly reduce facial bioburden.

Conclusions

Multiple factors influence SM bioburdens. Mask B showed the lowest bioburden and best protection effects. Mask C is not recommended to be used, especially considering that surgeons do not wash the cloth masks daily. Unnecessary talking during operation is not recommended, and washing the face before surgery is not strictly necessary.

Passive Ceiling Light Disinfection System to Reduce Bioburden in an Intensive Care Unit

A ceiling-installed narrow spectrum (402-420 nm) bactericidal blue light disinfection system was installed in a large suburban medical intensive care unit (ICU) and evaluated for implementation feasibility and effectiveness in reducing environmental bioburden. Installation of 54 ceiling devices was accomplished at low cost and with minimal ICU process disruption. Postinstallation high-touch surface colony counts were significantly lower than preinstallation. Linear mixed modeling demonstrated a 21% average overall decrease in colony count after installation, with consistent reduction in colony counts starting from week 4 postinstallation. Automated technology is potentially more efficient in reducing environmental bioburden in the acute care setting compared with other bioburden reducing methods or can provide a robust compliment to manual cleaning.

Organic dust exposure in veterinary clinics: a case study of a small-animal practice in Portugal

Literature about occupational health in small-animal veterinary practices is scarce, but most of it has recognised a number of risks to be considered, including organic dust exposure. The aim of this pilot study was to assess organic dust, bacterial, and fungal contamination in the indoor environment of a typical Portuguese veterinary clinic but also to screen for azoleresistant fungi. To complement these findings we also analysed workers' nasal exudates for resistant bacteriota. Particles measurements included mass concentrations (PMC) of five particle sizes (PM0.5, PM1, PM2.5, PM5, PM10) and their counts (PNC). Indoor air samples were obtained from six locations as well as before and during cat dental cleaning and cultured on four media for bacterial and fungal assessment. An outdoor sample was also collected for reference Surface samples were taken from the same indoor locations using swabs and we also use electrostatic dust cloths as passive methods. PM10 showed the highest concentrations across the locations. Indoor air fungal loads ranged from 88 to 504 CFU m-3. The azole-resistant Aspergillus section Nigri was identified in one sample. Indoor air bacterial loads ranged from 84 to 328 CFU m-3. Nasopharyngeal findings in the 14 veterinary clinic workers showed a remarkably low prevalence of Staphylococcus aureus (7.1 %). Our results point to contamination with organic dusts above the WHO limits and to the need for better ventilation. Future studies should combine the same sampling protocol (active and passive methods) with molecular tools to obtain more accurate risk characterisation. In terms of prevention, animals should be caged in rooms separate from where procedures take place, and worker protection should be observed at all times.

Bioburden and transmission of pathogenic bacteria through elevator channel during endoscopic retrograde cholangiopancreatography: application of multiple-locus variable-number tandem-repeat analysis for characterization of clonal strains

OBJECTIVES

Endogenous and exogenous infection of the biliary tract could occur during endoscopic retrograde cholangiopancreatography.

METHODS

Bile samples of patients with hepatobiliary diseases, and swab samples of elevator channel samples of duodenoscope and washing instruments were prepared simultaneously and cultured aerobically and anaerobically. Antimicrobial susceptibility of the most common characterized bacterial species was tested, and their genetic relatedness was analyzed by multiple locus variable number of tandem repeats method.

RESULTS

Contamination with Pseudomonas aeruginosa was detected in 38.2% of the elevator channels' and 26.6% of the bile samples. Staphylococcus aureus, Enterococcus spp., Staphylococcus epidermidis, Escherichia coli, Enterobacter spp., and Clostridium perfringenes were among other bacterial isolates in the elevator channel swab samples. Highest antimicrobial resistance rate among P. aeruginosa isolates from the bile and swab samples were detected against gentamicin (100% and 73%, respectively), while the lowest one was measured to piperacillin-tazobactam (25% and 0%, respectively). Out of the 27 distinct MLVA profiles, relatedness of P. aeruginosa strains in the bile samples compared with those from the elevators was shown in three series of the samples.

CONCLUSION

Identity of P. aeruginosa strains among the bile and elevator channel samples showed possibility of cross-contamination among patients even at distinct time intervals. Expert opinion: Bacterial infection is considered as main complications of ERCP. Entry of bacteria into the biliary tract via contaminated device and its related instruments and their proliferation in this tissue could cause serious infections. To prevent this side effect, reprocessing of medical equipment via standard cleaning and disinfection procedures are needed. Our results showed incompliance of methods used for endoscope cleaning and disinfection procedure. Although host risk factors, such as sphincterotomy, could increase rate of infection with different types of bacteria, their ability for formation of biofilm and spore, which could help them to resist disinfectants and washing procedures seems to be main cause of persistent colonization and transmission among different patients. New standards for disinfection compared with currently used methods and use of materials to eliminate formation of bacterial microcolonies seem to be necessary to prevent cross-contamination.

Efficacy of Intraoperative Implant Prophylaxis in Reducing Intraoperative Microbial Contamination

STUDY DESIGN

A prospective single-center study.

OBJECTIVES

Assess to what degree contamination of pedicle screws occur in standard intraoperative practice and if use of an impermeable guard could mitigate or reduce such an occurrence.

METHODS

Two groups of sterile prepackaged pedicle screws, one with an intraoperative guard (group 1) and the other without such a guard (group 2), each consisting of 5 samples distributed over 3 time points, were loaded onto the insertion device by the scrub tech and left on the sterile table. Approximately 20 minutes later, the lead surgeon who had just finished preparing the surgical site touches the pedicle screw. Then instead of implantation it was transferred to a sterile container using fresh clean gloves for bacterial and gene analysis. Guarded screw implies that even after unwrapping from the package, the screw carries an impermeable barrier along its entire length, which is only removed seconds prior to implantation.

RESULTS

The standard unguarded pedicle screws presented bioburden in the range of 10⁵ to 10⁷ (colony forming units/implant) with bacterial genus mostly consisting of Staphylococcus and Micrococcus, the 2 most common genera found in surgical site infection reports. The common species among them were Staphylococcus epidermis, Staphylococcus aureus, Micrococcus luteus, and Staphylococcus pettenkoferi, whereas the guarded pedicle screws showed no bioburden.

CONCLUSIONS

Shielding the pedicle screws intraoperatively using a guard provides a superior level of asepsis than currently practiced. All unshielded pedicles screws were carrying bioburden of virulent bacterial species, which provides an opportunity for the development of postoperative infections.

Occupational exposure to bioburden in Portuguese bakeries: an approach to sampling viable microbial load

In bakeries, a number of operations such as mixing are associated with exposure to air-suspended flour dust and related bioburden. The aim of this study was to find the best active sampling approach to the assessment of occupational exposure to bioburden in Portuguese bakeries based on the data obtained with the use of specific impaction and impinger devices. We used impaction to collect fungal particles from 100 L air samples onto malt extract agar (MEA) supplemented with chloramphenicol (0.05 %). For growing fungi we also used dichloran glycerol (DG18) agar-based media and for mesophilic bacteria we used tryptic soy agar (TSA) supplemented with nystatin (0.2 %). For Enterobacteriaceae we used violet red bile agar (VRBA). With impingers we also collected 300 L air samples at the 300 L/min airflow rate, inoculated onto the same culture media. The two methods, impaction and impinger, showed statistically significant differences in the following counts: fungal on MEA (z=-2.721, p=0.007), fungal on DG18 (z=-4.830, p=0.000), total bacteria (z=-5.435, p=0.000), and Gram-negative coliforms (z=-3.716, p=0.000). In all cases the impaction method detected significantly higher concentrations than the impinger method. Fungal and bacterial loads were higher in the production unit and lower in the shop. The fungal load obtained with impaction varied between 10 and 5140 CFU m-3, and total bacterial counts ranged between 10 and 4120 CFU m-3. This study has shown that the impaction method is the best active sampling approach to assessing viable bioburden in this specific occupational environment, but a multi-faceted approach to sampling and analyses combining methods and media enables a more refined risk characterisation and, consequently, better tailored risk control measures to reduce adverse health outcomes in workers.

Rapid Microbiology Screening in Pharmaceutical Workflows

Recently advances in miniaturization and automation have been utilized to rapidly decrease the time to result for microbiology testing in the clinic. These advances have been made due to the limitations of conventional culture-based microbiology methods, including agar plate and microbroth dilution, which have long turnaround times and require physicians to treat patients empirically with antibiotics before test results are available. Currently, there exist similar limitations in pharmaceutical sterility and bioburden testing, where the long turnaround times associated with standard microbiology testing drive costly inefficiencies in workflows. These include the time lag associated with sterility screening within drug production lines and the warehousing cost and time delays within supply chains during product testing. Herein, we demonstrate a proof-of-concept combination of a rapid microfluidic assay and an efficient cell filtration process that enables a path toward integrating rapid tests directly into pharmaceutical microbiological screening workflows. We demonstrate separation and detection of Escherichia coli directly captured and analyzed from a mammalian (i.e., CHO) cell culture with a 3.0 h incubation. The demonstration is performed using a membrane filtration module that is compatible with sampling from bioreactors, enabling in-line sampling and process monitoring.

The feasibility of gamma radiation sterilization for decellularized tracheal grafts

OBJECTIVES/HYPOTHESIS

The most promising stem cell-derived tracheal transplantation approach is dependent upon the use of decellularized tracheal grafts. It has been assumed that a sterilization step, such as gamma radiation, would damage the delicate extracellular matrix of the graft, thus rendering it less viable for cellular repopulation, although this has not been thoroughly investigated.

STUDY DESIGN

Laboratory-based comparative analysis.

METHODS

Fifteen murine tracheas of strain C57/B-6 mice were obtained. Thirteen were subjected to a detergent-enzymatic decellularization process. Of these decellularized tracheas (DT), eight were irradiated, exposing five tracheas to a radiation level of 25 kGy (DT25) and three to 5 kGy (DT5). Two were left untreated. The two untreated tracheas, two DTs, and two DT25s were prepared and examined using both scanning and transmission electron microscopy. Bioburden calculations were obtained from three DTs, three DT25s, and three DT5s by homogenization, serial dilution, and streak plating.

RESULTS

Electron microscopy of untreated fresh tracheas and DTs showed a slight qualitative degradation of cartilage ultrastructure due to the decellularization process. In contrast, examination of DT25 shows significant degradation including poor overall preservation of cartilage architecture with disorganized collagen fibers. The nonirradiated DTs had a calculated bacterial bioburden of 7.8 × 10⁷ to 3.4 × 10⁸ colony-forming units per gram. Both the DT25 and DT5 specimens were found to have a bioburden of zero.

CONCLUSIONS

Gamma radiation at 25 kGy degrades the architecture of decellularized tracheal grafts. These ultrastructural changes may prove detrimental to graft viability; however, bioburden calculations suggest that a 5 kGy radiation dose may be sufficient for sterilization.

LEVEL OF EVIDENCE

NA Laryngoscope, 127:E258-E264, 2017.

Guideline Implementation: Processing Flexible Endoscopes

The updated AORN "Guideline for processing flexible endoscopes" provides guidance to perioperative, endoscopy, and sterile processing personnel for processing all types of reusable flexible endoscopes and accessories in all procedural settings. This article focuses on key points of the guideline to help perioperative personnel safely and effectively process flexible endoscopes to prevent infection transmission. The key points address verification of manual cleaning, mechanical cleaning and processing, storage in a drying cabinet, determination of maximum storage time before reprocessing is needed, and considerations for implementing a microbiologic surveillance program. Perioperative RNs should review the complete guideline for additional information and for guidance when writing and updating policies and procedures.

Residual contamination and bioburden after reprocessing of single-use endoscopic ultrasound needles: An ex vivo study

BACKGROUND AND AIM

Endoscopic ultrasound (EUS) aspiration needles are single-use devices. However, in many centers, because of cost-constraints, these devices are reused multiple times. We studied microbiological contamination and bioburden on reprocessed needles to evaluate whether these devices can be successfully sterilized.

METHODS

We studied 10 EUS needles each of 19 G, 22 G, and 25 G in size, and five 22-G ProCore needles. After initial use, each needle was reprocessed by a standardized protocol. We used standard microbiological cultures, as well as ATP bioluminescence technique to quantify bioburden as relative light units (RLU). We defined significant soil contamination by RLU values >200. We also used extractant fluid to disrupt cell membranes in an attempt to enhance ATP detection.

RESULTS

We found culture positivity in 3/34 (8.8%), and detectable bioburden on the exposed surface of 33/35 (94.3%), and inside lumen of 29 (82.9%) reprocessed FNA needles. Significant bioburden was found in three (8.6%) and two (5.7%) needles on the surface and lumen, respectively. We found that use of extractant fluid enhanced detection of bioburden. Larger (19 G) needles had higher surface contamination (P = 0.016), but there was no relation of luminal contamination with needle diameter (P = 0.138). Sheath design and presence of side bevel did not influence extent of contamination. There was significant correlation between the surface and intraluminal bioburden (P < 0.001).

CONCLUSIONS

There is significant bioburden in reprocessed EUS needles; standard microbiological cultures have low sensitivity for detection of needle contamination. We have provided objective evidence for the futility of reprocessing attempts, and practice of EUS needle reuse should be discontinued.

The Immediate and Delayed Post-Debridement Effects on Tissue Bacterial Wound Counts of Hypochlorous Acid Versus Saline Irrigation in Chronic Wounds

Introduction: Wound debridement is considered essential in chronic wound management. Hypochlorous acid has been shown to be an effective agent in reducing wound bacterial counts in open wounds. Ultrasound-enabled wound debridement is an effective and efficient method of debridement. This study compared ultrasound irrigation with hypochlorous acid versus saline irrigation for wound debridement on pre- and postoperative wounds and determined regrowth of bacteria over 1 week period of time. Finally, the outcome of definitive wound closure of the clinically clean-appearing wounds was recorded. Methods: Seventeen consenting adult patients with chronic open wounds were randomly selected for study. The patients were randomly divided into the hypochlorous acid irrigation or saline irrigation group. All patients provided pre- and postoperative tissue samples for qualitative and quantitative bacteriology. For the time (7 days) between the debridement procedure and the definitive closure procedure, the wounds were dressed with a silver-impregnated dressing and a hydroconductive dressing. Results: Both types of irrigation in the ultrasonic system initially lowered the bacterial counts by 4 to 6 logs. However, by the time of definitive closure, the saline-irrigated wounds had bacterial counts back up to 10⁵ whereas the hypochlorous acid-irrigated wounds remained at 10² or fewer. More than 80% of patients in the saline group had postoperative closure failure compared with 25% of patients in the hypochlorous acid group. Conclusions: Hypochlorous acid irrigation with ultrasound debridement reduced bacterial growth in chronic open wounds more efficiently than saline alone. Postoperative wound closure outcomes suggest a remarkable reduction in wound complications after wound debridement using hypochlorous acid irrigation with ultrasound versus saline alone.

Utilizing the VeraFlo™ Instillation Negative Pressure Wound Therapy System with Advanced Care for a Case Study

Background: Mankind has always suffered wounds throughout time due to trauma, disease, and lifestyles. Many wounds are non-healing and have continued to be challenging. However, utilizing advanced wound care treatments, such as negative pressure wound treatment with instillation and dwell time (NPWTi-d), has proven beneficial.

NPWTi-d is indicated in a variety of wounds, such as trauma, surgical, acute, pressure injuries, diabetic foot ulcers, and venous leg ulcers. Bacteria and bioburden interrupts wound healing by increasing the metabolic needs, ingesting, and robbing the necessary nutrients and oxygen.

Instillation therapy is the technique of intermittently washing out a wound with a liquid solution. The mechanism of action is instilling fluid into the wound bed, soaking for a determined time, loosening and cleaning of exudate, contaminants, and/or infection, removing fluid via negative pressure, thus promoting tissue growth.

Case study: The patient was diagnosed with a large lymphedema mass on the right upper thigh. Surgical removal of the lymphedema mass was indicated due to interference with quality of life. After a failed flap and surgical debridement, NPWTi-d with normal saline was implemented.

Results: The patient had excellent results, with obvious forming of red, beefy granulation, epithelization tissue development, and a cleaner, healthier wound bed. Settings for the NPWTi-d was 18 minutes dwell time, every 2.5 hours with a constant pressure of 125 mm/hg pressure.

Conclusion: The NPWTi-d demonstrated to be an instrumental treatment in supporting and stimulating healing. Early application of the treatment with normal saline as the instillation fluid prepared the previously failed wound for quicker healing.

Evaluating the effectiveness of ultraviolet-C lamps for reducing keyboard contamination in the intensive care unit: A longitudinal analysis

BACKGROUND

Ultraviolet (UV) spectrum light for decontamination of patient care areas is an effective way to reduce transmission of infectious pathogens. Our purpose was to investigate the efficacy of an automated UV-C device to eliminate bioburden on hospital computer keyboards.

METHODS

The study took place at an academic hospital in Chicago, Illinois. Baseline cultures were obtained from keyboards in intensive care units. Automated UV-C lamps were installed over keyboards and mice of those computers. The lamps were tested at varying cycle lengths to determine shortest effective cycles. Delay after use and prior to cycle initiation was varied to minimize cycle interruptions. Finally, 218 postinstallation samples were analyzed.

RESULTS

Of 203 baseline samples, 193 (95.1%) were positive for bacteria, with a median of 120 colony forming units (CFU) per keyboard. There were numerous bacteria linked to health care-associated infections (HAIs), including Staphylococcus, Streptococcus, Enterococcus, Pseudomonas, Pasteurella, Klebsiella, Acinetobacter, and Enterobacter. Of the 193 keyboards, 25 (12.3%) had gram-negative species. Of 218 postinstallation samples, 205 (94%) were sterile. Of the 13 that showed bacterial growth, 6 produced a single CFU. Comparison of pre- and post-UV decontamination median CFU values (120 and 0, respectively) revealed a >99% reduction in bacteria.

CONCLUSIONS

The UV lamp effectively decontaminates keyboards with minimal interruption and low UV exposure. Further studies are required to determine reduction of HAI transmission with use of these devices.

Evaluation of two types of swabs for sampling allograft musculoskeletal tissue

BACKGROUND

Allograft musculoskeletal tissue is commonly sampled by a swab for bioburden screening. To determine if bioburden recovery could be improved at the pre-analytical stage, two swab systems were evaluated: the Amies gel swab and the ESwab.

METHODS

In vitro studies were performed to determine the recovery of each swab system with <100 colony-forming unit of challenge organisms using inoculated swabs and by sampling inoculated femoral heads. The standard culture protocol used in this laboratory was also evaluated after sampling of inoculated femoral heads. A prospective study was performed with both swab systems used in parallel to sample cadaveric allograft musculoskeletal tissue.

RESULTS

The challenge organisms could be recovered from the in vitro inoculated studies. The standard culture protocol in this laboratory recovered all challenge organisms from both swab systems. One hundred and six paired Amies and ESwabs were collected from eight cadaveric donors with skin commensals the predominant isolates.

CONCLUSIONS

The sampling of an inoculated femoral head was included to reflect routine swab sampling practice as was the inclusion of the standard method used in this laboratory. This appears to be the first study to compare Amies gel swabs with ESwabs to sample allograft femoral heads and in a prospective study with cadaveric allograft musculoskeletal tissue. Other comparative studies of swab systems have used a much higher inoculum to mimic an infection; however, sepsis is an exclusion criterion for allograft donors. It was found that the Amies gel swab and ESwab are both suitable sampling devices for bioburden testing of allograft musculoskeletal tissue.