Potential Cross-contamination Research Articles

High prevalence of multidrug-resistant bacteria in fomites in a tertiary institution in Southwestern Nigeria

<b>Background</b><b>: </b>The emergence and spread of multidrug-resistant (MDR) bacteria have become a major threat to public and environmental health because they limit treatment options against infections. Fomites have been implicated in the spread of pathogenic and resistant bacteria, making them an important source of disease. This study was carried out to determine the frequency and characteristics of resistant bacteria linked with environmental fomites in a tertiary institution in Nigeria as part of global efforts to provide information to contain the spread of antimicrobial resistance.<br /> <b>Methods: </b>300 swab samples, determined by factorial design, were aseptically collected from 10 fomites in 10 locations in three different facilities at Obafemi Awolowo University, Nigeria, and transported to the laboratory for processing. The isolates were identified by standard procedure and the Microbact<sup>TM</sup> identification kit. The susceptibility profile of the isolates was determined using Kirby-Bauer disc diffusion technique. MDR bacteria were examined for the presence of plasmids using the alkali lysis method, and plasmid-mediated quinolone resistance, extended-spectrum beta-lactamase, and methicillin resistance genes by polymerase chain reaction.<br /> <b>Results:</b> 89 diverse bacteria were isolated from fomites in the study environment. <i>Staphylococcus aureus </i>(49.4%) predominated among the bacteria, followed by <i>Staphylococcus saprophyticus</i> (10.1%), <i>Providencia stuartti</i> (5.6%), <i>Proteus vulgaris</i> (4.5%), and<i> Acinetobacter baumannii</i> (3.4%). The isolates were commonly (84%-100%) resistant to ceftazidime, cefuroxime, and augmentin, while the least (8%-12.5%) resistance was to ciprofloxacin, amikacin, meropenem, and streptomycin. 58 (65.2%) isolates were MDR, and the majority (27.6%) were isolated from floors. 47 (81%) MDR isolates harbored plasmids, with their molecular weights between 2.697 kbp and 4.011 kbp. <i>mecA</i>, <i>TEM,</i> and <i>OqXAB</i> resistance genes were detected in <i>S. aureus</i>, <i>P. stuarttii</i>, <i>Pseudomonas </i>sp, and <i>K. oxytoca</i>.<br /> <b>Conclusions:</b> This study has shown that fomites in the sampled locations are potential reservoirs for MDR bacteria, and may serve as sources of their transmission, thereby posing a threat to public health. Therefore, appropriate sanitary measures are required to prevent any potential cross-contamination. In addition, it is imperative to regularly survey environments for bacterial contamination to increase community awareness and education regarding hygiene standards.

A New Broad-Spectrum Drug Screen for 127 Analytes by LC-MS/MS.

Broad-spectrum drug screening is offered by many clinical laboratories to support investigation of possible drug exposures. The traditional broad-spectrum drug screen employed at our laboratory utilizes several different analytical platforms, thus requiring relatively high volumes of sample and a cumbersome workflow. Here we describe the development and validation of a consolidated broad-spectrum drug screen assay designed to qualitatively detect 127 compounds in urine (Ur) and serum/plasma (S/P) samples. An LC-MS/MS method was developed using the Ultivo LC-MS/MS and designed to be qualitative with a 1-point calibration curve and 50% to 150% controls. Sample preparation included the addition of 122 internal standards (IS) followed by mixed-mode strong cation exchange solid-phase extraction and reverse-phase chromatographic separation on a biphenyl column. For the method described herein, ≥ 95% of analytes in urine and serum control samples had a CV of ≤20% for total imprecision. Accuracy testing included 46 external controls and demonstrated 99.9% accuracy. Method comparison studies to quantitative testing are discussed. The high level of coverage of the analytes with a stable isotope-labeled IS (SIL-IS) helped normalize for matrix effects when significant ion suppression (>25%) was present. Analyte stability in the matrix, the impact of potentially interfering compounds, and method ruggedness were demonstrated. Method limitations include limited detection of glucuronidated drugs and potential cross-contamination with samples at very high concentrations (>>100 × cutoff). The broad-spectrum drug screen method developed here qualitatively detected 127 drugs and select metabolites. This method could be used to support investigations of possible drug exposures in a clinical setting.

Hand hygiene behavior change: a review and pilot study of an automated hand hygiene reminder system implementation in a public hospital.

To review and study implementation of an automated hand hygiene reminder system (AHHRS). Prospective, nonrandomized, before-after quality improvement pilot study conducted over 6 months. Medical-surgical unit (MSU) and medical intensive care unit (MICU) at a public hospital in New York City. There were 2,642 healthcare worker observations in the direct observation (DO) period versus 265,505 in the AHHRS period, excluding AHHRS observations collected during the 1-month crossover period when simultaneous DO occurred. We compared hand hygiene adherence (HHA) measured by DO prior to the pilot and after AHHRS implementation. We compared changes in HHA and potential cross-contamination events (CCEs) (room exit and subsequent entry without HHA) from baseline for each biweekly period during the pilot. Engagement, education/training, data transparency, and optimization period resulted in successful implementation and adoption of the AHHRS. Observations were greater utilizing AHHRS than DO (265,505 vs 2,642, P < .01). Due to the expected Hawthorne effect, HHA was significantly less for AHHRS than DO in MSU (90.99% vs 97.21%, P < .01) and MICU (91.21% vs 98.65%, P < .01). HHA significantly improved from 86.47% to 89.68% in MSU (P < .001) and 85.93% to 91.24% in the MICU (P < .001) from the first biweekly period of AHHRS utilization to the last. CCE decreased from 73.42% to 65.11% in the MSU and significantly decreased from 81.22% to 53.19% in the MICU (P < .05). We describe how an AHHRS approach was successfully implemented at our facility. With ongoing feedback and system optimization, AHHRS improved HHA and reduced CCE over time.

Efficacy of the feed additive consisting of Bacillus velezensis NRRL B-67257 (Correlink™ ABS747) as a feed additive for all growing poultry species (Elanco GmbH).

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the efficacy of a product consisting of viable spores of Bacillus velezensis NRRL B-67257 as a zootechnical additive for chickens for fattening, chickens reared for laying, turkeys for fattening, turkeys reared for breeding and minor poultry species. The additive has the tradename Correlink™ ABS747 Bacillus subtilis and is not currently authorised in the European Union. It is intended for use in complete feed for the target species at a minimum inclusion level of 1.5× 108CFU/kg complete feed. In a previous opinion the FEEDAP Panelcould not conclude on the efficacy of the additive for the poultry species due to the potential cross-contamination of the control diets in two of the three studies provided. The applicant has provided supplementary information to exclude this possibility. The new data showed that the gene used as marker in the previous analyses is non-specific of the NRRL B-67257 strain, which precluded the adequate quantification of the active agent in the feeds used in the studies. Moreover, in a second analysis, the active agent could not be isolated from the field excreta samples collected from either from the treated or the control group of one of the formerly submitted efficacy studies. The Panelconcluded that the methodology was not able to discriminate between the strain under assessment and the background. Therefore, the FEEDAP Panelwas not in the position to conclude on the efficacy of Correlink™ ABS747 for all growing poultry species based on the data newly provided.

Quantitative Determination of Campylobacter on Broilers along 22 United Kingdom Processing Lines To Identify Potential Process Control Points and Cross-Contamination from Colonized to Uncolonized Flocks

As part of a program to reduce numbers of the human pathogen Campylobacter on retail chickens, 22 broiler processing lines, representing more than 90% of UK production, were characterized by enumerating Campylobacter on pooled neck skins after exsanguination, scalding, defeathering, evisceration, crop removal, inside-outside washing, and air-chilling stages of processing. Sixteen of the processing lines investigated showed significant (P < 0.05) reductions in Campylobacter numbers because of carcass scalding. However, in all of these lines, the following defeathering stage caused a significant increase in Campylobacter contamination that effectively negated the reductions caused by scalding. On four processing lines, primary chilling also caused a significant reduction in numbers of Campylobacter. On three lines, there was a significant microbiological benefit from inside-outside washing. The stages where Campylobacter numbers were reduced require further investigation to determine the specific mechanisms responsible so that the observed pathogen reductions can be optimized and then more widely implemented. The transfer of up to 4 log CFU Campylobacter per g of neck skin from a colonized flock to a following uncolonized flock was observed. Cross-contamination was substantial and still detectable after 5,000 carcasses from an uncolonized flock had been processed. Numbers of Campylobacter recovered from the uncolonized flocks were highest on the first of the uncolonized birds to pass along the line, and in general, the numbers declined as more uncolonized birds were processed. Air sampling recovered low numbers at the processing stages monitored, indicating that airborne transmission was unlikely to be the primary transfer mechanism operating for cross-contamination between flocks.

Efficacy of the feed additive consisting of Bacillus velezensis NRRL B‐67259 (Correlink™ ABS1781) as a feed additive for all growing poultry species (Elanco GmbH)

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the efficacy of a product consisting of spores of Bacillus velezensis NRRL B-67257 as a zootechnical additive for chickens for fattening, chickens reared for laying, turkeys for fattening, turkeys reared for breeding and minor poultry species. The additive has the tradename Correlink™ ABS1781 Bacillus subtilis and is not currently authorised in the EU. It is intended for use in complete feed for the target species at a minimum inclusion level of 1.5× 108CFU/kg complete feed. In a previous opinion, the FEEDAP Panelcould not conclude on the efficacy of the additive for the poultry species due to the potential cross-contamination of the control diets in two of the three studies provided. The applicant has provided supplementary information to exclude this possibility. The new data showed that the gene used as marker in the previous analyses is non-specific of the NRRL B-67259 strain, which precluded the adequate quantification of the active agent in the feeds used in the studies. Moreover, in a second analysis, the active agent could not be isolated from the field excreta samples collected from either the treated or the control group in the two formerly submitted efficacy studies. The Panelconcluded that the methodology was not able to discriminate between the strain under assessment and the background. Additionally, two new efficacy trials with chickens for fattening were provided to support the efficacy of the additive. However, none could be further considered since the husbandry conditions in which the birds were kept were non-compliant with Directive 2007/43/EC. Therefore, the FEEDAP Panelwas not in the position to conclude on the efficacy of Correlink™ ABS1781 for all growing poultry species.

PREDICTORS OF UNFAVOURABLE OUTCOME IN PATIENTS ON MAINTENANCE HEMODIALYSIS WITH SARS COV 2 INFECTION

Introduction:The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection was discovered in December 2019 in Wuhan, China, and quickly gave rise to a devastating pandemic. Due to uraemia-related immune system dysfunction, pro-inammatory state , higher comorbidity burden, and the potential of cross-contamination from dialysis centres; patients on maintenance haemodialysis appear to be particularly prone to SARS-CoV-2 infection. Materials and Methods The retrospective observational study aimed to determine the clinical, biochemical, pharmacological, and radiological prognosticators of favourable outcomes in patients on maintenance haemodialysis with COVID-19 infection. It included all adult patients who were on haemodialysis therapy and were admitted to B.M.H.Gimcare hospital, Kanuur , Kerala ; with a positive real-time reverse transcription-polymerase chain reaction for SARS-CoV-2 between September 2020 to February 2021, identied from the electronic medical records system. Result: The mean age of the study's 21 males and nine females was 61.47 years; of these patients, nine succumbed to their illness. The mean age of the deceased (67.11 ± 12.34 years), dialysis vintage period (31.67 ± 7.48 months), and duration of hospital stay (13 ± 8 days) were higher than those of the survivors (59.05 ± 11.42 years, 15.71 ± 7.24 months, and 8.67 ± 4.23 days, respectively). The TLC at admission (14033.33 ± 14423.07 per µL), N/L ratio (6.27 ± 6.38), and lactate dehydrogenase serum (457.11 ± 245.26) were also signicantly higher in those who had an unfavourable outcome. All cases on femoral dialysis access succumbed to this virus. Conclusion: We postulate that the outcome will be unfavourable in COVID-19 patients on heparin-free haemodialysis via femoral access, with higher total leukocyte levels, a raised neutrophil-lymphocyte ratio, lactate dehydrogenase and quick sequential organ failure assessment scores of more than two requiring invasive ventilatory support at admission.

Bacterial Cross-Transmission between Inanimate Surfaces and Patients in Intensive Care Units under Real-World Conditions: A Repeated Cross-Sectional Study.

Background/Objectives: Contaminated surfaces play an important role in the nosocomial infection of patients in intensive care units (ICUs). This study, conducted in two ICUs at Edouard Herriot Hospital (Lyon, France), aimed to describe rooms’ microbial ecology and explore the potential link between environmental contamination and patients’ colonization and/or infection. Methods: Environmental samples were realized once monthly from January 2020 to December 2021 on surfaces close to the patient (bedrails, bedside table, and dedicated stethoscope) and healthcare workers’ high-touch surfaces, which were distant from the patient (computer, worktop/nurse cart, washbasin, and hydro-alcoholic solution/soap dispenser). Environmental bacteria were compared to the cultures of the patients hospitalized in the sampled room over a period of ± 10 days from the environmental sampling. Results: Overall, 137 samples were collected: 90.7% of the samples close to patients, and 87.9% of the distant ones were positives. Overall, 223 bacteria were isolated, mainly: Enterococcus faecalis (15.7%), Pantoea agglomerans (8.1%), Enterobacter cloacae/asburiae (6.3%), Bacillus cereus and other Bacillus spp (6.3%), Enterococcus faecium (5.8%), Stenotrophomonas maltophilia (5.4%), and Acinetobacter baumannii (4.9%). Throughout the study, 142 patients were included, of which, n = 67 (47.2%) were infected or colonized by at least one bacterium. In fourteen cases, the same bacterial species were found both in environment and patient samples, with the suspicion of a cross-contamination between the patient–environment (n = 10) and environment–patient (n = 4). Conclusions: In this work, we found a high level of bacterial contamination on ICU rooms’ surfaces and described several cases of potential cross-contamination between environment and patients in real-world conditions.

Cross-contamination by COVID-19 mask microfibers during microlitter analysis of marine biota

Face masks have been adopted as an essential measure to prevent transmission and spread of the virus infection during the pandemic of Covid-19. The present study evaluates the potential microfibers transfer from face masks to other recipients and the potential cross-contamination of samples by microfibers released from masks worn during the analysis of microlitter ingestion by fish. Results indicated that masks could easily transfer endogenous (originated from the mask tissue itself) and exogenous microfibers (with a different origin than the mask tissue itself) to other recipients (adhesive tape and air in our experiment). Exogenous fibers may be carried from everywhere and potentially released everywhere. Microfibers are also released into the air, driven by the airflow generated by breathing, and can be transferred to blanks and samples. Microfiber contamination by facial masks increases the risk of samples cross-contamination and raises concerns about the results reliability of the microlitter analysis on marine biota.

Translanguaging and power in academic writing discourse: the case of a Bangladeshi university

ABSTRACT This study explored the role of translanguaging pedagogies in navigating bilingual students’ tensions and struggles in an academic writing class of an English medium private university in Bangladesh. Data were collected through classroom observation, a pedagogical intervention, a focus group discussion with six students and a semi-structured interview with the class teacher. The analysis of observation data revealed that the gate-keeping encounters precipitated by the English-only policy affected student engagement and class participation. In contrast, the intervention designed through several translanguaging strategies enhanced students’ metalinguistic, metacognitive and sociolinguistic awareness, developed multicompetence, and facilitated full participation rate in an academic writing task. Irrespective of these benefits, participants expressed mixed reactions toward accepting translanguaging as a regular practice and a policy in writing instruction that might challenge language separation traditions in academic writing, English-only biases, and expressed views about the potential for cross-contamination of Bangla language and linguistic nationalism in Bangladesh.

Quantitative assays to test for presence of cross-contamination in allergen-specific oral immunotherapy products

Cross-contamination is a common cause of adverse food reactions that remains an ongoing challenge for the safety of patients with food allergies, especially those with concurrent diagnoses. It is concerning that oral immunotherapy (OIT) products are often manufactured in shared facilities and may risk cross-contamination. In this study, we explored potential cross-contamination in OIT products manufactured by the Stanford Sean N. Parker Center for Allergy and Asthma Research.

Self-Reported Dietary Choices and Oral Health Care Needs during COVID-19 Quarantine: A Cross-Sectional Study.

The COVID-19 pandemic significantly impacted the healthcare system, including dentistry. However, it is not entirely clear whether affected patients’ willingness for regular dental visits and preventive behaviors with regards oral hygiene and diet. This is essential to understanding the potential effects of the COVID-19 pandemic on the acceleration of dental issues in the future. It was aimed at checking the level of dental visit avoidance, self-reported oral health needs, and dietary changes. This cross-sectional questionnaire study conducted in Poland (n = 2574; mean age 44.4 ± 15.6; female 56.3%) assessed nutritional habits and dental care changes during the COVID-19 pandemic. As demonstrated, nearly half of the responders (47.1%) avoided regular dental visits, while only 0.5% used online consultations. Fears related to potential cross-contamination in dental offices dropped from 25% to 11.4% and were associated with increased BMI and age (p < 0.05). Sweet snacking/drinking confirmed 19.1%/33.2% subjects. Self-reported oral health care needs (tooth stain, calculus, gingivitis, loss of fillings) were related to frequent snacking and poor oral hygiene (p < 0.05). The study highlights that pandemic periods are covered by eating and drinking changes combined with inadequate hygiene and dental care impose health complaints in the oral cavity. This can magnify both nutritional and interrelated oral health issues, highlighting the need to implement preventive and mitigation measures.

Antibiogram Profile of Enteric Pathogens Isolated from Fomites in Cross River University of Technology Medical Centre, Calabar, Nigeria

Background: Healthcare environments are considered as potential reservoirs for pathogenic microorganisms especially those responsible for nosocomial infections. Such microorganisms often present with varying degrees of drugs resistance. This study was aimed at evaluating the Cross River University of Technology (CRUTECH) Medical Center Environment for the presence of pathogenic bacterial contaminants and antibiotics susceptibility profile of such isolates.&#x0D; Materials and Methodology: A total of 72 swab samples were collected from nineteen frequently touched hospital surfaces and processed using the standard bacteriological procedures. The emergent bacterial colonies were identified using phenotypic and biochemical tests. Antibiotic susceptibility testing of the presumptively identified isolates was carried out using Kirby-Bauer’s method.&#x0D; Results: Out of 72 swab samples collected, 44 (61.1%) were positive for Enteric bacterial pathogens. The mean viable count ranged from 1.8 x 106 Cfu/cm2 (weighing scales) to 2.41 x 107 Cfu/cm2 (wash sinks). The most prevalent isolate was E. coli (48 of 127, 37.8%) followed by Klebseilla sp (27 of 127, 21.3%), Salmonella sp (19 of 127, 14.9%), Proteus sp (12 of 127, 9.4%), Citrobacter sp (11 of 127, 8.7%), Enterobacter sp (7 of 127, 5.5%) while Shigella sp (3 of 127, 2.4%) was least isolated. Isolates demonstrated high level of susceptibility to Norfloxacin 124 (97.6%), Imipenem 116 (91.3%) and Chloramphenicol 105 (82.7%). Resistance to Erythromycin was 95 (74.8%), Gentamycin 84 (66.1%) and Amikacin 82 (64.6%).&#x0D; Conclusion: Contamination of healthcare surfaces by multi-drugs resistant pathogens is a potential risk, especially to hospitalized patients and health care workers. Thus, it is therefore imperative that appropriate hygienic measures be implemented to suppress any potential microbial cross-contamination.

Hepatitis E virus cross-contamination on the surface of porcine livers after storage in Euro meat containers in a German pig abattoir

Hepatitis E virus (HEV) is a foodborne zoonotic pathogen and known as the causative agent of hepatitis E in humans. The specific role of porcine liver as a vehicle for human HEV infections has been highlighted in different studies. Nevertheless, gaps of knowledge still exist regarding possible HEV cross-contamination both at consumer and production level. Furthermore, people working in the food production industry, e.g. veterinarians and abattoir employees, are exposed to an increased risk of HEV infection. The aim of the present study was to investigate HEV cross-contamination on the surface of porcine liver in a German abattoir. The sample set included 250 samples of porcine liver parenchyma and the corresponding 250 superficial layer samples of the same livers, which were analyzed for the presence of HEV ribonucleic acid (RNA). Afterwards, the initial status of the tested liver parenchyma was compared with the occurrence of HEV RNA in the corresponding superficial layer. HEV RNA was detectable in 34% (85/250) of superficial layer samples, with 58% (49/85) of the samples originated from initially HEV negative livers. To our knowledge, this is the first study that provides an insight in the potential of HEV cross-contamination at abattoir level in Germany. Furthermore, it could be identified that the joint storage of livers in Euro meat containers has a significant impact on the presence of HEV RNA on the surface of porcine liver.

SANITASI ALERGEN PADA PROSES PRODUKSI BISKUIT DALAM UPAYA MENGURANGI RESIDU ALERGEN TELUR

Food allergy is a hypersensitive response to food, generally protein, triggered by body immune system. These responses can be mild, however in very rare cases may cause severe reactions and life threatening known as called anaphylaxis. Food allergy has been one of the main factors for product recall. It can happen due to many reasons, such as product package labeling fault, raw material labeling fault and cross contamination. Validation of the effectiveness of cleaning and sanitation process become a critical point to minimize cross contamination. This study aimed to determine the optimum chemical concentration and contact time to eliminate egg residue in biscuit production cleaning process, obtain valid and verified cleaning procedures, and produce cleaning procedures that can be implemented in a production line. The result showed that physical cleaning/pre-cleaning for 30 minute and using 1% (v/v) concentration of caustic based polybrite chemical cleaning for 3-minute contact time can effectively eliminate the egg residue on stainless steel and polyurethane surface equipment. Food contact surface material and product characteristics (wet dough, dry biscuit) affected the number of egg residue on the equipment. Packing area with food contact surface equipment made from stainless steel is not considered critical area for allergen sanitation. It is shown that prior to sanitation process, analysis of egg allergen residue has already given negative result. Validation process can prove the effectiveness of allergen sanitation process to prevent potential egg allergen cross contamination in biscuit production.

Pyrolysis-GC×GC-TOFMS as a tool for distinguishing the macromolecular structure of nitrogen-bearing animal biopolymers in fossil tissues

With the increasing interest in characterization of biopolymers in fossils and their preservation mechanisms, there has been a concomitant increase in reports of preservation of such macromolecules in organic remains of varying ages. However, there have also been several criticisms of these reports involving N-bearing macromolecules such as difficulty in determining endogeneity, and potential for cross-contamination.We explore the utility of pyrolysis comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry as a technique that could potentially provide reproducible data to address some of those criticisms. We find that the enhanced separation capacity of this technique and its ability to resolve complex compounds in low abundances could potentially allow for more specificity in compound assignments. We attempt to understand its diagnostic efficacy by analysing industry standards of chitin and collagen, and a well-documented fossil melanin from Jurassic squid ink. We find that the distribution of nitrogen-bearing compounds in relation to the non-nitrogenous products in each of the above three biomacromolecules is characteristic: acetamide, acetic acid, levoglucosenone and a suite of N-bearing compounds for standard chitin, N-bearing compounds with a distinct region of substituted cyclic 2,5-diketopiperazines (2,5-DKPs) for standard collagen, and a mixture of N-bearing compounds for fossil melanin. We suggest that 3-acetamidofuran and higher homologues, and 3-acetamidopyrones and higher homologues could be reliable markers for N-acetyl-D-glucosamine, of which chitin is a homomer, and that 2,5-DKPs are reliable markers for proteins – particularly collagen, while conceding that assigning a marker purely based on pyrolysis products is difficult for melanin. We then analyse an Eocene mammal bone to make a preliminary investigation into the viability of this technique. We find that the distribution of pyrolysis products is characteristic and distinguishable even in this fossil material, suggesting that proteins like collagen can potentially be detected even when possibly preserved in a degraded form. We conclude that Py-GC×GC-TOFMS is a promising method yielding reliable data that can be used to distinguish between nitrogen-bearing biomacromolecules, possibly even in fossil tissues, and should be the focus of further analyses.

Contamination by antimicrobial-resistant enterobacteria isolated from cell phones and hands in a veterinary hospital.

Hospital infections are of great relevance in human and animal health, and fomites are important in the spread of pathogens in hospital units. The aim of this study was to investigate the frequency of enterobacteria in the operating room of a veterinary hospital, the potential cross-contamination of samples, and to characterise the susceptibility profile of the isolates to antimicrobials. Sixty-five samples were collected from five different surgical procedures. These samples came from the hands and cell phones of the surgical team and pet owners, operating tables, and patients. Species detection was performed through polymerase chain reaction, genetic diversity by pulsed-field gel electrophoresis (PFGE), and susceptibility to antimicrobials through an antibiogram. Escherichia coli and Proteus mirabilis isolates were obtained from eight samples, from the hands of the anaesthesiologist, the pet owner, and the surgeon; the surgeon's, the nurse's and the anaesthesiologist's cell phones, and two surgical tables. Furthermore, PFGE showed high genetic diversity among the isolates, which showed multidrug resistance. The identification of multidrug-resistant E. coli and P. mirabilis on cell phones of the surgical team is a major concern and, although no direct correlation was found, the isolation of these bacteria inside the clean area of the operating room shows the possibility of nosocomial transmission from cell phones to susceptible patients.

P–153 Comparison outcome of vitrified human embryos stored in vapor phase liquid nitrogen (LN2) and direct LN2

Abstract Study question Is vapor cryopreserved LN2 storage beneficial for clinical outcomes of vitrified human embryos that are frozen compared to vitrified human embryos having direct contact with LN2. Summary answer There are no significant differences compared to clinical outcomes of human embryos stored in LN2 vapor and direct store in LN2. What is known already There has been concerned about potential cross-contamination and biohazard issues of embryos for long term storage using direct LN2. This study aimed to compare clinical outcomes of human embryos transfer between vapor phase and liquid LN2. Study design, size, duration The embryo has undergone vitrification for long term storage with vapor or direct contact in LN2. After the thawing of the embryo, we checked on the survival rates. We transferred only one or two embryos per patient and kept analyzing the implantation and pregnancy rates Participants/materials, setting, methods This retrospective study was carried out from January 2018 to December 2019 with 3272cycles 4713embryos; vitrified for long term storage in vapor phase or direct contact with LN2. We compared the clinical outcomes of frozen embryo transfer cycles using vitrified for long term storage in vapor phase and direct contact with LN2. Clinical outcomes monitored were embryo survival, subsequent implantation and pregnancy after single or double embryo transfer Main results and the role of chance A total of 4713 fertilized human embryos are vitrified and then stored in LN2 vapor (n = 2520 cycles) or direct contact LN2 (n = 752 cycles). The study showed that the blastocyst stored in vapor able to retain full development. Survival was 97.8% (vapor) and 97.6% (direct contact LN2), and the vapor storage of human embryos had no significant difference in survival rates after a long term storage. For single blastocyst transfer, pregnancy and implantation rates were 51.5%, 52.4% in vapor, 54.6%, 54.9% in direct LN2; respectively (p=NS). In double blastocyst transfer, the pregnancy and implantation rates were 61.8%, 42.0% in vapor and 64.7%, 44.5% in direct LN2; respectively (p=NS). There were also no significant differences between two groups. Limitations, reasons for caution The study showed that the blastocyst stored in vapor can retain full development. A vapor storage system thus is safe and effective for long term vapor storage of vitrified human embryos.Within the limits of this study, there was no detection of an adverse effect of vapor storage. Wider implications of the findings: Vapor storage systems thus represent a useful alternative for safe and effective long-term storage of vitrified human embryos that can avoid cross contamination chances from having direct contact with LN2. Trial registration number Not applicable

P–549 What trophectoderm cells from mosaic embryos tell us about embryonic competence at the transcriptional level

Abstract Study question Does transcriptome of remaining trophectoderm (TE) reflect the developmental potential of mosaic blastocysts after preimplantation genetic testing for aneuploidy (PGT-A)? Summary answer: TE from low-degree mosaic (Low-mos) and high-degree mosaic (High-mos) blastocysts are transcriptionally equivalent, standing between euploid and aneuploid categories and displaying key deregulated developmental processes. What is known already Blastocysts classified as mosaic by PGT-A are associated with lower implantation and higher miscarriage rates than those classified as euploid, yet they still lead to healthy babies. Unveiling the true developmental identity of these embryos faces a dilemma: understanding to which extent they represent technical artefacts or whether they hold own potential to implant and give rise to normal pregnancies. Current RNA sequencing (RNA-seq) techniques allow for the determination of whole transcriptomic profiles even from single cells, which paves the way for the identification of new molecular keys of embryonic competence. Study design, size, duration Prospective study comparing RNA-seq data of remaining TE from blastocysts classified as euploid (n = 4), Low-mos (n = 5), High-mos (n = 4) and aneuploid (n = 6) by PGT-A. Participants were recruited between October 2018 and November 2019 at IVI-RMA Valencia. Participants/materials, setting, methods Chromosomal mosaicism was defined in the range 30%-&amp;lt;50% (Low-mos) and 50%-&amp;lt;70% (High-mos) using a next-generation sequencing (NGS) validated algorithm. Whole TE fractions were separately collected and processed for RNA-seq. Differentially expressed genes (DEGs) were calculated with DESeq2 package [Benjamini-Hochberg (BH)-adjusted p &amp;lt; 0.01 &amp; abs(log2FoldChange)&amp;gt;2 significant]. Fgsea algorithm was used for enrichment analysis on Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways and Gene Ontology (GO) terms (BH-adjusted p &amp;lt; 0.01 significant). Main results and the role of chance For comparisons, TE from euploid blastocysts were used as control. At the gene level, 15 DEGs were found in Low-mos, 20 DEGs in High-mos, and 64 DEGs in aneuploid blastocysts. To address the functional implications of these differences, pathways significantly deregulated according to KEGG and GO categories were identified. TE from aneuploid blastocysts displayed significant downregulation in up to 115 KEGG and GO processes directly involved in processing and integrity maintenance of nuclear and mitochondrial genomes, a reflection of their aberrant chromosomal identity. In addition, TE from High-mos and Low-mos were transcriptionally equivalent (0 DEGs between both groups), with 23 overlapping KEGG and GO processes significantly downregulated compared with control. Importantly, main significantly-affected processes included mitotic sister chromatid segregation, NIK NF-kB activity, regulation of apoptosis, and pathways related to the biosynthesis and metabolism of proteins, fatty acids, carbohydrates and steroid hormones. These findings indicate that mosaic embryos comprise a unique developmental entity, which swims between the euploid and aneuploid waterfronts and may regulate survival by diverse mechanisms, including cell proliferation and apoptosis. Limitations, reasons for caution This is a descriptive, single-center study with limited sample size. TE fractions were obtained by micromanipulation, which may have led to potential cross-contamination with the inner cell mass. Wider implications of the findings: Transcriptomic equivalence between Low-mos and High-mos TE fractions questions the biological significance of inferring mosaicism degrees from single biopsies. Deregulated processes in these embryos support their reduced developmental and live birth potential, pointing to mechanisms that may mediate survival in the presence of aneuploid cells, as shown in the mouse. Trial registration number Not applicable

P-549 What trophectoderm cells from mosaic embryos tell us about embryonic competence at the transcriptional level

Abstract Study question Does transcriptome of remaining trophectoderm (TE) reflect the developmental potential of mosaic blastocysts after preimplantation genetic testing for aneuploidy (PGT-A)? Summary answer TE from low-degree mosaic (Low-mos) and high-degree mosaic (High-mos) blastocysts are transcriptionally equivalent, standing between euploid and aneuploid categories and displaying key deregulated developmental processes. What is known already Blastocysts classified as mosaic by PGT-A are associated with lower implantation and higher miscarriage rates than those classified as euploid, yet they still lead to healthy babies. Unveiling the true developmental identity of these embryos faces a dilemma: understanding to which extent they represent technical artefacts or whether they hold own potential to implant and give rise to normal pregnancies. Current RNA sequencing (RNA-seq) techniques allow for the determination of whole transcriptomic profiles even from single cells, which paves the way for the identification of new molecular keys of embryonic competence. Study design, size, duration Prospective study comparing RNA-seq data of remaining TE from blastocysts classified as euploid (n = 4), Low-mos (n = 5), High-mos (n = 4) and aneuploid (n = 6) by PGT-A. Participants were recruited between October 2018 and November 2019 at IVI-RMA Valencia. Participants/materials, setting, methods Chromosomal mosaicism was defined in the range 30%- &amp;lt; 50% (Low-mos) and 50%- &amp;lt; 70% (High-mos) using a next-generation sequencing (NGS) validated algorithm. Whole TE fractions were separately collected and processed for RNA-seq. Differentially expressed genes (DEGs) were calculated with DESeq2 package [Benjamini-Hochberg (BH)-adjusted p &amp;lt; 0.01 &amp; abs(log2FoldChange)&amp;gt;2 significant]. Fgsea algorithm was used for enrichment analysis on Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways and Gene Ontology (GO) terms (BH-adjusted p &amp;lt; 0.01 significant). Main results and the role of chance For comparisons, TE from euploid blastocysts were used as control. At the gene level, 15 DEGs were found in Low-mos, 20 DEGs in High-mos, and 64 DEGs in aneuploid blastocysts. To address the functional implications of these differences, pathways significantly deregulated according to KEGG and GO categories were identified. TE from aneuploid blastocysts displayed significant downregulation in up to 115 KEGG and GO processes directly involved in processing and integrity maintenance of nuclear and mitochondrial genomes, a reflection of their aberrant chromosomal identity. In addition, TE from High-mos and Low-mos were transcriptionally equivalent (0 DEGs between both groups), with 23 overlapping KEGG and GO processes significantly downregulated compared with control. Importantly, main significantly-affected processes included mitotic sister chromatid segregation, NIK NF-kB activity, regulation of apoptosis, and pathways related to the biosynthesis and metabolism of proteins, fatty acids, carbohydrates and steroid hormones. These findings indicate that mosaic embryos comprise a unique developmental entity, which swims between the euploid and aneuploid waterfronts and may regulate survival by diverse mechanisms, including cell proliferation and apoptosis. Limitations, reasons for caution This is a descriptive, single-center study with limited sample size. TE fractions were obtained by micromanipulation, which may have led to potential cross-contamination with the inner cell mass. Wider implications of the findings Transcriptomic equivalence between Low-mos and High-mos TE fractions questions the biological significance of inferring mosaicism degrees from single biopsies. Deregulated processes in these embryos support their reduced developmental and live birth potential, pointing to mechanisms that may mediate survival in the presence of aneuploid cells, as shown in the mouse. Trial registration number Not applicable