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During the development of vaccines, bacterial colony forming units (CFUs) are counted in order to quantify the yield in the fermentation process. This manual task is time-consuming and error-prone. In this work we test multiple segmentation algorithms based on the U-Net CNN architecture and show that these offer robust, automated CFU counting. We show that the multiclass generalisation with a bespoke loss function allows distinguishing virulent and avirulent colonies with acceptable accuracy. While many possibilities are left to explore, our results show the potential of deep learning for separating and classifying bacterial colonies., 6 pages, 2 figures, accepted at ESANN 2020 (European Symposium on Artificial Neural Networks, Computational Intelligence and Machine Learning)

Purpose : To determine the effect of Inherited Cleft Lip and Palate Management on microbial migration in forked lip and palate (CLP) children. Material and methods: Fifteen forked lip and palate children and fifteen standard children (the control group), aged 3 months to 36 months were selected from the out clinic of Faculty of Dental Medicine, Al-Azhar University for Girls. Dribble samples were collected after the breakfast by inserting sterile cotton gauze in the entry from the jaws before and after construction of obturator. Results: The highest (mean±SD) value of log bacterial count (CFU/μl) was found in the cleft patients pre-operatively (5.64±1.06), while post-operatively there was a significant reduction in value (0.60±0.06) (P

Student clinicians are expected to encounter microorganisms during the process of thepatients’ treatment that can cause various diseases. In the Dentistry’s Prosthodontics clinicmanual, dental students should perform disinfection but no specific method wasrecommended. This study utilized the True experimental research design to evaluate theeffectiveness of two ethyl alcohol disinfection methods (spray and immersion) in thereduction of the bacterial colony count on dental casts and when running tap water is used torinse the dental casts. Informed consent from the 34 participants was first secured from eachof them. They were purposively selected based on their age and if they were partiallyedentulous with at least ten teeth present in each arch. Sixty eight dental casts were producedafter the impression taking of both their maxillary and mandibular arches, 34 of which werefor the experimental group and 34 were for the control group. The Streaking Plate Techniquewas used in determining the bacterial colony count on each dental cast before and after thedisinfection. The results were analyzed statistically using one-way ANOVA. Results revealedthat both the immersion and spray methods in which 70% ethyl alcohol was used as adisinfectant, were found to be independently effective as compared with tap water rinsingonly in reducing the bacterial colony count of each dental cast. However, when the two ethylalcohol disinfection techniques were compared to each other, results showed that there wereno significant statistical differences between them when the ability to reduce the bacterialcolony count on dental casts was observed. From the conclusions, it is recommended that theDentistry students consider using either the immersion or spray method with 70% ethylalcohol as a disinfectant on dental casts. Further studies may also be done to test differentkinds of alcohols with various concentrations.

Background In the health care setting, infection control actions are fundamental for containing the dissemination of multidrug-resistant bacteria (MDR). Carbapenemase-producing Enterobacterales (CPE), especially Klebsiella pneumoniae (CR-KP), can spread among patients, although the dynamics of transmission are not fully known. Since CR-KP is present in wastewater and microorganisms are not completely removed from the toilet bowl by flushing, the risk of transmission in settings where toilets are shared should be addressed. We investigated whether urinating generates droplets that can be a vehicle for bacteria and explored the use of an innovative foam to control and eliminate this phenomenon. Methods To study droplet formation during urination, we set up an experiment in which different geometrical configurations of toilets could be reproduced and customized. To demonstrate that droplets can mobilize bacteria from the toilet bowl, a standard ceramic toilet was contaminated with a KPC-producing Klebsiella pneumoniae ST101 isolate. Then, we reproduced urination and attached culture dishes to the bottom of the toilet lid for bacterial colony recovery with and without foam. Results Rebound droplets invariably formed, irrespective of the geometrical configuration of the toilet. In microbiological experiments, we demonstrated that bacteria are always mobilized from the toilet bowl (mean value: 0.11 ± 0.05 CFU/cm2) and showed that a specific foam layer can completely suppress mobilization. Conclusions Our study demonstrated that droplets generated from toilets during urination can be a hidden source of CR-KP transmission in settings where toilets are shared among colonized and noncolonized patients.

medical and dental treatment in the form of ozonized water and oxygen / ozone gas mixture and associated with photobiomodulation therapy. The evidence map was based on the 3iE evidence searched in the databases: LILACS, PubMed, EMBASE and Cochrane Library, seeking systematic and narrative reviews, analyzed in an excel characterization spreadsheet. Three independent literature reviewers screened the systematic review search output blinded at the software Rayyan. The full-text publications were screened against the specified inclusion criteria by thre independent reviewers; disagreements were resolved through discussion. Forty-two studies were found, 16 of which were systematic reviews and 26 narrative reviews, published between 2006 and 2021, with different levels of confidence. The intervention that most appeared in the literature was oral ozone therapy as a bacterial colony reduction and decontamination agent, with emphasis on topical oxygen-ozone gas mixtures, topical ozonized water. Oral ozone therapy can bring benefits to clinical practice and patients. The evidence map provides an easy visualization of valuable information for patients, health practitioners and managers, in order to promote evidence-based complementary therapies. Este estudio tuvo como objetivo hacer el mapa de evidencias sobre la ozonoterapia, como abordaje integrador y / o complementario al tratamiento médico y odontológico en forma de agua ozonizada y mezcla de oxígeno / ozono gaseoso y asociado a la terapia de fotobiomodulación. El mapa de evidencia se basó en la evidencia 3iE buscada en las bases de datos: LILACS, PubMed, EMBASE y Cochrane Library, buscando revisiones sistemáticas y narrativas, analizadas en una hoja de cálculo de caracterización en Excel. Tres revisores independientes de la literatura examinaron el resultado de la búsqueda de la revisión sistemática cegados en el software Rayyan. Tres revisores independientes examinaron las publicaciones de texto completo en función de los criterios de inclusión especificados; Los desacuerdos fueron resueltos mediante una discusión. Se encontraron 42 estudios, 16 de los cuales fueron revisiones sistemáticas y 26 revisiones narrativas, publicados entre 2006 y 2021, con diferentes niveles de confianza. La intervención que más apareció en la literatura fue la ozonoterapia oral como agente reductor de colonias bacterianas y descontaminación, con énfasis en mezclas tópicas de oxígeno-ozono gaseoso, agua ozonizada tópica. La ozonoterapia oral puede aportar beneficios a la práctica clínica y a los pacientes. El mapa de evidencia proporciona una visualización fácil de información valiosa para pacientes, profesionales de la salud y administradores, con el fin de promover terapias complementarias basadas en evidencia. Este estudo teve o objetivo de realizar um mapa de evidências sobre a ozonioterapia, como abordagem integrativa e / ou complementar ao tratamento médico-odontológico na forma de água ozonizada e mistura de oxigênio / gás ozônio e associada à fotobiomodulação. O mapa de evidências baseou-se nas evidências 3iE pesquisadas nas bases de dados: LILACS, PubMed, EMBASE e Biblioteca Cochrane, buscando revisões sistemáticas e narrativas, analisadas em planilha de caracterização excel. Três revisores independentes da literatura examinaram o resultado da pesquisa da revisão sistemática cegos para o software Rayyan. As publicações de texto completo foram selecionadas de acordo com os critérios de inclusão especificados por três revisores independentes; desacordos foram resolvidos por meio de discussão. Foram encontrados 42 estudos, sendo 16 revisões sistemáticas e 26 revisões narrativas, publicadas entre 2006 e 2021, com diferentes níveis de confiança. A intervenção que mais apareceu na literatura foi a terapia de ozônio oral como agente de redução e descontaminação de colônias bacterianas, com ênfase em misturas tópicas de oxigênio-ozônio e água ozonizada tópica. Conclusão: A ozonioterapia oral pode trazer benefícios à prática clínica e aos pacientes. O mapa de evidências fornece uma visualização fácil de informações valiosas para pacientes, profissionais de saúde e gestores, a fim de promover terapias complementares baseadas em evidências.

One of the most delicate stages of an evolutionary algorithm is the evaluation of the goodness of the solutions by some procedure providing a fitness value. However, although there are general rules, it is not always easy to find an appropriate evaluation function for a given problem. In the biological realm, today, there is a variety of experimental methods under the name of microbial screening to identify and select bacteria from their traits, as well as to obtain their fitness. In this paper, we show how given an optimization problem, a colony of synthetic bacteria or bacterial agents is able to evaluate the fitness of candidate solutions by building an evaluation function. The evaluation function is obtained simulating, in silico, a bacterial colony conducting the laboratory methods used in microbiology, biotechnology and synthetic biology to measure microbial fitness. Once the evaluation function is built, it is included in the code of the genetic algorithm as part of the fitness routine. The practical use of this approach is illustrated in two classic optimization problems. In silico routines have been programmed in Gro, a cell programming language oriented to synthetic biology, and can easily be customized to many other optimization problems.

Rhinology studies anatomy, physiology and diseases affecting the nasal region: one of the most modern techniques to diagnose these diseases is nasal cytology or rhinocytology, which involves analyzing the cells contained in the nasal mucosa under a microscope and researching of other elements such as bacteria, to suspect a pathology. During the microscopic observation, bacteria can be detected in the form of biofilm, that is, a bacterial colony surrounded by an organic extracellular matrix, with a protective function, made of polysaccharides. In the field of nasal cytology, the presence of biofilm in microscopic samples denotes the presence of an infection. In this paper, we describe the design and testing of interesting diagnostic support, for the automatic detection of biofilm, based on a convolutional neural network (CNN). To demonstrate the reliability of the system, alternative solutions based on isolation forest and deep random forest techniques were also tested. Texture analysis is used, with Haralick feature extraction and dominant color. The CNN-based biofilm detection system shows an accuracy of about 98%, an average accuracy of about 100% on the test set and about 99% on the validation set. The CNN-based system designed in this study is confirmed as the most reliable among the best automatic image recognition technologies, in the specific context of this study. The developed system allows the specialist to obtain a rapid and accurate identification of the biofilm in the slide images.

We report a highly-sensitive, high-throughput, and cost-effective bacteria identification system which continuously captures and reconstructs holographic images of an agar-plate and analyzes the time-lapsed images with deep learning models for early detection of colonies. The performance of our system was confirmed by detection and classification of Escherichia coli, Enterobacter aerogenes, and Klebsiella pneumoniae in water samples. We detected 90% of the bacterial colonies and their growth within 7-10h (>95% within 12h) with ~100% precision, and correctly identified the corresponding species within 7.6-12h with 80% accuracy, and achieved time savings of >12h as compared to the gold-standard EPA-approved methods.

Numerous studies have investigated the influence of orthodontic therapy and appliances on the oral microbial flora. Little is known about the effect of removable orthodontic appliances on oral colonisation by mutans streptococci. The original aim of the present investigation was to assess the mean and the statistical mean difference of colony values of S. Mutans in a removable orthodontic appliance fabricated from two types of acrylic resin for an Iraqi sample. According to certain predetermined sample criteria; the present study consist of eleven consecutive young patients scheduled for orthodontic treatment with removable orthodontic appliances at the department of orthodontics at the college of dentistry/ University of babylon as well as dental student seeking orthodontic treatment. Each subject included in the present study had to wear an upper (hot cured) and lower (cold cured) well adaptive removable orthodontic appliance. A swab was taken from the lingual/palatal gingival and inoculated within the brain heart agar then cultured within Mitis- Salivarius Bacitracin (MSB) agar. The colonies were calculated for each plate, afterwards the colony forming unit (CFU) will be calculated. of the present study showing that all bacterial colony values were higher in the lower than upper arch. However, a statistical non significant difference was registered between the colony mean values of both arches. The present study signify both types of acrylic resins (heat/ cold) can be used as an orthodontic acrylic base in removable appliances within the orthodontic practice with a careful monitoring of patients treated orthodontically for risk of caries development.

The present work explores bacterial colonies and their individual and social behaviours under the lens of complex adaptive systems. We initially provide a background on the biology of bacteria to describe important phenomena, such as quorum-sensing, individual and collective behaviours, adaptation, evolution and self-organization over the influence of mechanical effects on bacterial systems and connecting scales. We then explore some associations between bacterial colonies and complex adaptive systems by considering components and ownerships of self-organization. The main contribution of this paper places emphasis on individual decision-making and behaviour as a cause of bacterial colonies’ actions, i.e., how self-organization and collective behaviours impact the ability of a bacterial colony to address an environmental stimulus and maintain itself as an open biological and fault-tolerant system. Finally, we conclude the work and provide some comments regarding future research.

Counting bacterial colonies on microbiological culture plates is a time-consuming, error-prone, nevertheless essential quantitative task in Clinical Microbiology Laboratories. With this work we explore the possibility to find effective solutions to the above issue by designing and testing two different machine learning approaches. The first one is based on the extraction of a complete set of handcrafted morphometric and radiometric features used within a Support Vector Machines solution. The second one is based on the design and configuration of a Convolutional Neural Networks deep learning architecture. To validate, in a real and challenging clinical scenario, the proposed bacterial load estimation techniques, we built and publicly released a fully labeled large and representative database of both single and aggregated bacterial colonies extracted from routine clinical laboratory culture plates. Dataset enhancement approaches have also been experimentally tested for performance optimization. The adopted deep learning approach outperformed the handcrafted feature based one, and also a conventional reference technique, by a large margin, becoming a preferable solution for the addressed Digital Microbiology Imaging quantification task, especially in the emerging context of Full Laboratory Automation systems.

Viable air particles pose a risk in areas where sterile preparations are compounded. This study investigated the efficacy of an innovative air purification technology that uses a shielded ultraviolet C light lamp to continuously purify the air in an inpatient pharmacy. Mean airborne fungal and bacterial colony forming units were obtained preinstallation and again in 6 months. A statistically significant decrease of 78% and 62% was observed for fungal and bacterial particles, respectively. This study demonstrates a potential role for this novel technology in decreasing the spread of airborne pathogens.

Introduction : Preterm and fullterm breast milk has different leukocyte and bioactive concentration, which affect it’s bactericidal activity and storage duration. The preterm breast milk potentially has longer storage duration than fullterm breast milk The research and guideline about the acceptable of storage duration of preterm breast milk at 4 o C was limited. The objective of this study was to assess the correlation of storage duration of preterm breast milk preterm baby at 4 o C temperature on bacterial growth. Methods : The study design was experimental using pre-post control groups design. We used 9 samples of breast milk which met the inclusion criteria divided into 3 groups. The first, second and third groups was storage in 4 o C for 0, 24 and 48 hours respectively before the inoculation to the culture media. Results : After the samples were kept at 4 o C temperature for 0, 24 and 48 hours, the mean bacterial colony forming unit for each group were 92 (±SD 112), 79 (±SD 97) and 63 (±SD 73) CFU respectively. Compared to the first group, the second and third group has lower bacterial colony forming unit but no significant differences statistically (P= 0.214 and P=1.39 respectively). Likewise there was no significant bacterial colony forming unit between second and third group (P=0.086). Conclusion : Storage of preterm breast milk in 4 o C for 24 and 48 hours show no change in total bacterial colony count (TBCC)..

BACKGROUND: Hospital-acquired infection (HAI) is a major problem for the patient's health care and may impact the duration of treatment. Hand hygiene is a simple procedure but giving good prevention usually done among nurses at the hospital. AIM: Objective of the study is to determine the effectivity of handwashing method compared to hand rub to eliminate microorganisms on nurse’s hands at Sumatera Utara University Hospital. This is an experimental analytic study using random sampling technique. METHODS: There were 16 nurses enrolled in this study. There were 2 groups involved; the first group using handwashing with soap and the other one using hand rub. The swabs were taken from each hand from both groups before and after washing their hands. Moreover, the swabs directly sent to Microbiology Laboratory of Sumatera Utara University to identify bacteria which colonise the hand. RESULTS: There were no significant differences between using handwashing method compared to hand rub in reducing total bacterial colony on hands (p = 0.088). The average of total colony decreased by using handwashing method is 59.5%, and by using a hand, rub is 47.2%. CONCLUSION: Hand hygiene method using alcohol-based hand rub liquid has been recommended by WHO and can replace hand washing method in a particular situation.

Artur Yakimovich works in the field of computational virology and applies machine learning algorithms to study host-pathogen interactions. In this mSphere of Influence article, he reflects on two papers “Holographic Deep Learning for Rapid Optical Screening of Anthrax Spores” by Jo et al. (Y. Jo, S. Park, J. Jung, J., Artur Yakimovich works in the field of computational virology and applies machine learning algorithms to study host-pathogen interactions. In this mSphere of Influence article, he reflects on two papers “Holographic Deep Learning for Rapid Optical Screening of Anthrax Spores” by Jo et al. (Y. Jo, S. Park, J. Jung, J. Yoon, et al., Sci Adv 3:e1700606, 2017, https://doi.org/10.1126/sciadv.1700606) and “Bacterial Colony Counting with Convolutional Neural Networks in Digital Microbiology Imaging” by Ferrari and colleagues (A. Ferrari, S. Lombardi, and A. Signoroni, Pattern Recognition 61:629–640, 2017, https://doi.org/10.1016/j.patcog.2016.07.016). Here he discusses how these papers made an impact on him by showcasing that artificial intelligence algorithms can be equally applicable to both classical infection biology techniques and cutting-edge label-free imaging of pathogens.

Background To meet the nutritional needs of preterm infants, multicomponent nutrient fortifiers are added to human milk. The fortified human milk (FHM) product changes the physical and biochemical characteristics of the milk. We questioned whether such physical-chemical changes in the milk would alter intrinsic probiotic bacterial activity. The objective of the study was to evaluate the effect of osmolality and pH on the growth of probiotic bacterial species intrinsic to human milk. Methods Human milk samples (n = 26) were collected from mothers in the neonatal intensive care unit (NICU) and stored at −20°C until analyzed. The samples were thawed and divided into three portions. Human milk fortifiers (HMFs) were added to two portions to prepare concentrations of FHM. The remaining portion was the unfortified control sample. Each sample was then divided into two parts. One part (baseline) was used to measure the osmolality and pH and plated on selective agar to enumerate the growth of lactobacilli and bifidobacteria species. The remaining part was incubated at 37°C for 24 h to further test bacterial integrity (post-incubation) and then the same measurements were made (osmolality, pH, bacterial colony counts). Results When compared with unfortified milk at baseline, osmolality increased and pH decreased significantly after the addition of HMFs. Lactobacilli and bifidobacteria colony counts did not differ among the groups pre-incubation. Post-incubation lactobacilli and bifidobacteria increased in all the groups. Conclusion The appropriate addition of HMFs differentially affected the osmolality and pH of the milk. These physical changes did not affect the growth of probiotic bacterial species.

Background: There are various treatment protocols to manage the increased bacterial load in plantar ulcers. Recently, Controlled-Flux Electrolyzed Acidic Solution (CFEAS), with a pH less than 3, has appeared to be an effective option since its antimicrobial effect could help in the healing of those ulcers. In order to evaluate its potential in this sense, the aim of the present study was to compare bacterial growth on healthy hallucal skin using two types of bandaging (control and Controlled-Flux Electrolysed Acidic Solution). Material and methods: In a sample of 19 healthy subjects, two experiments were performed. In the first, for each subject, two identical hallux bandages were applied in the early morning. At random between left and right foot, either physiological saline (wetting every 2 h) was applied or nothing (control). In the second, two days later, new bandages were applied as before, but now either wetting with Controlled-Flux Electrolysed Acidic Solution (experimental, again wetting every 2 h) or nothing (control). In each experiment, the bacterial load in the nail fold was assessed at the first moment and after 10 h from standard counts of bacterial colony forming units (CFU). Results: In the first experiment, the CFU counts had increased significantly (p < 0.05) in both toes after the 10-h period. In the second experiment, while the bacterial load increased significantly (p = 0.001) from 0.68 ± 0.8 × 104 CFU/cm2 (the “pre” sample) to 1.3 ± 0.9 × 104 CFU/cm2 (the “post” sample) in the control toe, in the experimental CFEAS toe, the pre sample bacterial load was 0.61 ± 0.6 × 104 CFU/cm2 , and the post sample 0.9 ± 0.8 × 104 CFU/cm2 , with no significant difference between them (p = 0.221). Negative cultures were obtained in 3 cases (15.78%) of the experimental toe post sample, and equal post and pre counts in 2 cases (10.5%). Conclusion: Controlled-Flux Electrolyzed Acidic Solution has an effect on healthy hallucal skin that is bacteriostatic, and in some cases bactericidal. This effect could be very helpful in treating plantar ulcers when there is a greatly increased bacterial load in the wound, thus potentially favoring the normal formation of granulation tissue in the skin and normal healing and closure of the ulcer.

Background Bacterial colony morphology is the first step of classifying the bacterial species before sending them to subsequent identification process with devices, such as VITEK 2 automated system and mass spectrometry microbial identification system. It is essential as a pre-screening process because it can greatly reduce the scope of possible bacterial species and will make the subsequent identification more specific and increase work efficiency in clinical bacteriology. But this work needs adequate clinical laboratory expertise of bacterial colony morphology, which is especially difficult for beginners to handle properly. This study presents automatic programs for bacterial colony classification task, by applying the deep convolutional neural networks (CNN), which has a widespread use of digital imaging data analysis in hospitals. The most common 18 bacterial colony classes from Peking University First Hospital were used to train this framework, and other images out of these training dataset were utilized to test the performance of this classifier. Results The feasibility of this framework was verified by the comparison between predicted result and standard bacterial category. The classification accuracy of all 18 bacteria can reach 73%, and the accuracy and specificity of each kind of bacteria can reach as high as 90%. Conclusions The supervised neural networks we use can have more promising classification characteristics for bacterial colony pre-screening process, and the unsupervised network should have more advantages in revealing novel characteristics from pictures, which can provide some practical indications to our clinical staffs.

Aims To determine the antiseptic efficacy on bacterial colony counts of a 5- vs 10-minute surgical site scrub in urologic surgery. Methods A prospective cohort study was conducted in 101 patients presenting for elective urological procedures. Patients were randomized to a 5- or 10-minute groin scrub with Betadine (povidone-iodine). Skin swabs were taken immediately after skin clipping and following routine painting with Betadine. A third swab was taken after the betadine skin scrub. Bacterial colony counts were reported as a number of colony-forming units (CFUs). The primary outcome measure was a quantitative comparison of CFUs in the two arms. Results Fifty-three patients were randomized to a 5-minute scrub and 48 to a 10-minute scrub. After Betadine painting, CFUs were present in 38% of patients in the 5-minute group (mean, 33.5 CFU) and in 27% of the 10-minute group (mean, 45.4 CFU). Following the surgical scrub, only 7.5% of the 5-minute group and 8.3% of the 10-minute group had a measurable CFU count of greater than or equal to 1, and colony counts were low in both groups (5- minute group: mean, 1.5 CFU; 10-minute group: mean, 2.0 CFU). There was no significant difference in CFUs following a 5- or 10-minute scrub (P = 0.28). Conclusions The addition of a surgical skin scrub leads to a fourfold reduction in the skin CFU count compared with Betadine painting. However, there is no difference between the antibacterial effects of a 5- and 10-minute scrub. A 5-minute scrub may be sufficient in urologic prosthetic surgery.

Aim Neonatal infections carry a heavy burden of morbidity and mortality. Poor practice can result in unintentional colonisation of medical equipment with potentially pathogenic organisms. This study will determine the prevalence and type of bacterial contamination on exposed neonatal resuscitation equipment in different clinical settings and explore simple measures to reduce contamination risk. Methods A survey determined the rates of resuscitation equipment usage. All environmentally exposed items were identified on resuscitaires hospital-wide and swabbed for bacterial contamination. A new cleaning and storage policy was implemented and the prevalence of environmentally exposed equipment re-measured post-intervention. Results Resuscitation equipment was used in 28% of neonatal deliveries. Bacterial colony forming units were present on 44% of the 236 exposed equipment pieces swabbed. There was no significant difference in contamination rates between equipment types. Coagulase negative staphylococcus was the most prevalent species (59 pieces, 25%) followed by Escherichia coli and Enterobacter cloacae (20 pieces, 9% each). Opened items stored inside plastic remained sterile, whilst those in low-use areas had significantly less contamination than those in high-use areas (22% vs. 51%, P

Objective To compare the antibacterial efficacy of different surgical hand antisepsis protocols used by veterinary students. Study Design Prospective, randomized, controlled study. Study Population Third year veterinary students (n=45). Methods The participants were randomly assigned to 4 of the following 12 hand preparation product/time combinations: nonabrasive hand scrub method with 4% chlorhexidine gluconate (CH); hand rub with a mixture of 30% 1-propanol and 45% 2-propanol solution (MPS), 70% 2-propanol solution (IPS), or 61% ethanol solution with 1% chlorhexidine gluconate (ES/CH), with a contact time of 1.5, 3, or 5 minutes. Antibacterial efficacy was assessed after surgical hand preparation and at the end of surgery. Log reductions of total bacterial colony forming unit (CFU)/mL and positive aerobic culture rates were compared using multivariable analysis of variance and multivariable logistic regression, respectively. Results After surgical hand preparation, CH and ES/CH provided significantly higher log CFU reduction and lower positive culture rate for Gram-positive and spore-forming bacteria compared to MPS and IPS. Increase in contact time did not provide significant improvement in bacterial reduction. At the end of surgery, ES/CH provided significantly higher log CFU reduction compared to IPS and lower positive culture rate for Gram-positive bacteria compared to CH, MPS, and IPS. Increase in contact time significantly improved log CFU reduction in ES/CH and MPS groups. Conclusion In our population of veterinary students ES/CH hand rubs or CH scrubs were more effective in reducing bacterial CFU during surgical hand preparation than MPS or IPS.

On the base of the existing research study, a multi-period, multi-product, multi-supplier, single-manufacture, and multi-distributor supply chain model is considered in the paper. In the three-eche...

An animal laboratory in a teaching hospital is a possible cause of cross infection. We aimed to assess the infection control in our animal laboratory and evaluate the disinfectant effects of a portable pulsed xenon ultraviolet (PX-UV) machine. Samples were taken from the surface of research tables, other high touch places, such as doorknobs, weighing scales, and handles of trolleys, and from air in the barrier system pre- and post-manual cleaning and post-PX-UV disinfection. The bacteria types were identified. We found that routine manual cleaning significantly reduced bacterial colony form unit (CFU)/cm2 (P = .02), and the median of CFU/cm2 reduced from 0.5 pre-cleaning to zero post-cleaning. PX-UV disinfection also significantly reduced residual bacterial counts (P = .002), with the highest counts 10 pre-PX-UV disinfection and 1 afterwards. Without manual cleaning, PX-UV disinfected surfaces significantly (P, Highlights • An animal laboratory in a teaching hospital is a possible cause of cross infection. • The disinfectant effect of manual cleaning and portable pulsed xenon ultraviolet (PX-UV) was compared in our laboratory. • Manual cleaning significantly reduced bacterial counts on surfaces and PX-UV significantly reduced residual bacterial counts. • PX-UV, without manual cleaning, significantly reduced bacterial counts on surfaces. • PX-UV significantly reduced bacterial counts in the room air.

International audience; Elastic Light Scattering (ELS) is an innovative technique to identify bacterial pathogens directly on culture plates. Compelling results have already been reported for agri-food applications. Here, we have developed ELS for clinical diagnosis, starting with Staphylococcus aureus early screening. Our goal is to bring a result (positive/negative) after only 6 h of growth to fight surgical-site infections. The method starts with the acquisition of the scattering pattern arising from the interaction between a laser beam and a single bacterial colony growing on a culture medium. Then, the resulting image, considered as the bacterial species signature, is analyzed using statistical learning techniques. We present a custom optical setup able to target bacterial colonies with various sizes (30-500 microns). This system was used to collect a reference dataset of 38 strains of S. aureus and other Staphyloccocus species (5459 images) on ChromIDSAID/ MRSA bi-plates. A validation set from 20 patients has then been acquired and clinically-validated according to chromogenic enzymatic tests. The best correct-identification rate between S. aureus and S. non-aureus (94.7%) has been obtained using a support vector machine classifier trained on a combination of Fourier-Bessel moments and Local- Binary-Patterns extracted features. This statistical model applied to the validation set provided a sensitivity and a specificity of 90.0% and 56.9%, or alternatively, a positive predictive value of 47% and a negative predictive value of 93%. From a clinical point of view, the results head in the right direction and pave the way toward the WHO’s requirements for rapid, low-cost, and automated diagnosis tools.

Urine is the excretory product of the body produced by the process of filtration, reabsorption, and tubular secretion. Urine can be collected and examined easily, and presence of certain substances in the urine may indicate the metabolic state of the body. The routine and microscopic examinations of urine are helpful in the diagnosis of several pathological conditions. A random sample is usually taken for routine clinical examination; however, first-morning urine is preferred for urinalysis and microscopic analysis, since it is generally more conc. Fresh or preserved urine samples are used for chemical and culture-based microbiological testing. The specimens that are unpreserved for more than 2 h or refrigerated for a long time may not be suitable for analysis due to potential bacterial overgrowth and invalidation of bacterial colony counts or errors in chemical urinalysis.

In this paper, we introduce a new method for the segmentation of bacterial colonies in solid agar plate images. The proposed approach comprises two contributions. First, a simple but nonetheless effective engine is devised to generate synthetic plate images. This engine overlays bacterial colony patches to existing background images, taking into account both the local appearance of the background and the intrinsic opacity of the bacterial colonies. Therefore, a scalable alternative to the human ground–truth supervision—often difficult to obtain in medical imaging, due to privacy issues and scarcity of data—is provided. Then, synthetic generated data, together with few annotated images, were used to train a Fully–Convolutional Network. Such network is actually effective in separating bacterial colonies from the background. Finally, we discuss the role of the generation of synthetic images, conducting experiments that show how their inclusion improves the performances of the segmentation network, producing very encouraging results.

Nosocomial infections (NI) are infections contracted during the cause of hospital treatments, which are secondary to the patients’ original condition. A retrospective survey of nosocomial infection rates was carried out, using patients’ medical files and diagnosis index. Surfaces of non-invasive fomites which frequently come in contact with patients were swabbed; drip stands, door knobs, fan switches, bed rails, bed linens, pillow cases, light-plug-ins, and sink knobs for microbial contamination. Microbes isolated from the 225 swabs samples were identified using standard microbiological methods. An overall prevalence of 11.9% nosocomial infections was recorded. The Intensive Care Unit (37.5%) and Children ward (7.6%) recorded the highest and lowest prevalence respectively. Prevalence of nosocomial infections in the sampled wards was significantly different at (P>0.05). Door knobs (22.76%) recorded the highest microbial contamination; while light-plug-ins (4.88%) and pillow case (4.88%) were the least contaminated fomites. The highest bacterial colony count of 9.6 × 106 cfu/ml which is higher than the infectious dose of 106 cfu/ml was recorded on the door knob of Female surgical ward while pillow case shows insignificant count across most wards. Surface contamination of fomites within healthcare setting is significant issue of concern in public health thus the need to implement strict policy to reduce the rate of surface bio-contamination of hospital environment.

Timely and accurate bacterial detection is critical for various health and safety applications, which promotes the continuous development of versatile optical sensors for bacterial investigations. Here, we report a new strategy for bacterial colony sensing using terahertz (THz) imaging with minimal assay procedures. The proposed method utilizes the acute sensitivity of THz wave to the changes in the water content and cellular structures. Single bacterial colonies of 4 bacterial species were directly distinguished using THz imaging by utilizing their differences in THz absorption. In addition, the distribution of mixed bacterial samples has been demonstrated by THz imaging, which demonstrated that the target bacterium could be easily recognized. Furthermore, we investigated the differentiation of bacterial viability, which indicated that bacteria under different living states could be distinguished by THz imaging because of their different hydration levels and cellular structures. Our results suggest that THz imaging has the potential to be used for mixed bacterial sample detection and bacterial viability assessment in a label-free and nondestructive manner.

Turning is deemed as one of the most fundamental processes of metal cutting in industry. The heat generated in the cutting zones during turning plays an essential role in the final workpiece quality and power consumption. The present work tried to elaborate the performance of a new cooling technique i.e. pre-cooling the workpiece integrated with a developed cutting fluid applied with minimum quantity cooling lubrication method. To do so, to produce the desirable eco-friendly and user-friendly cutting fluid, water mixed vegetable oil was combined with a little amount of anti-bacterial agent and a scented essence. To assess the machining parameters in question i.e. surface roughness, consumed machining power and chip formation as well as machining hazards, some tests were conducted on the hardened and tempered AISI 1045 steel. Based on the findings of the study, a great improvement was observed in terms of machining parameters as well as health and ecological-related issues. The better machining performance of the new method probably is mainly due to efficient penetration of the oil into the tool–workpiece interface and colder cutting zone when compared with the conventional machining. Also, compared to the straight oil, the new vegetable oil showed positive results in terms of controlling the growth of bacterial colony. It seems that the proposed combined cooling method may potentially enhance the productivity of cutting operations in terms of machining quality, costs, operator health and environmental protection.

Background and Objective: The recent introduction of Full Laboratory Automation systems in clinical microbiology opens to the availability of streams of high definition images representing bacteria culturing plates. This creates new opportunities to support diagnostic decisions through image analysis and interpretation solutions, with an expected high impact on the efficiency of the laboratory workflow and related quality implications. Starting from images acquired under different illumination settings (top-light and back-light), the objective of this work is to design and evaluate a method for the detection and classification of diagnostically relevant hemolysis effects associated with specific bacteria growing on blood agar plates. The presence of hemolysis is an important factor to assess the virulence of pathogens, and is a fundamental sign of the presence of certain types of bacteria. Methods: We introduce a two-stage approach. Firstly, the implementation of a highly accurate alignment of same-plate image scans, acquired using top-light and back-light illumination, enables the joint spatially coherent exploitation of the available data. Secondly, from each segmented portion of the image containing at least one bacterial colony, specifically designed image features are extracted to feed a SVM classification system, allowing detection and discrimination among different types of hemolysis. Results: The fine alignment solution aligns more than 98.1% images with a residual error of less than 0.13 mm. The hemolysis classification block achieves a 88.3% precision with a recall of 98.6%. Conclusions: The results collected from different clinical scenarios (urinary infections and throat swab screening) together with accurate error analysis demonstrate the suitability of our system for robust hemolysis detection and classification, which remains feasible even in challenging conditions (low contrast or illumination changes).

This paper proposes a novel bacterial colony foraging (BCF) algorithm for complex optimization problems. The proposed BCF extend original bacterial foraging algorithm to adaptive and cooperative mode by combining bacterial chemotaxis, cell-to-cell communication, and a self-adaptive foraging strategy. The cell-to-cell communication enables the historical search experience sharing among the bacterial colony that can significantly improve convergence. With the self-adaptive strategy, each bacterium can be characterized by focused and deeper exploitation of the promising regions and wider exploration of other regions of the search space. A rigorous performance analysis is given where the proposed algorithm is benchmarked against four state-of-the-art reference algorithms using both a classical and a composition test function suites. The individual and collective bacterial foraging behaviors of the proposed algorithmic model are also studied. Statistical analysis of all these tests highlights the significant performance improvement due to the beneficial combination and shows that the proposed algorithm outperforms the reference algorithms.

This study aimed to analyse the odour retention characteristics of different textile fibers. The commercially used textile fibers like cotton, viscose, linen, nylon, 60/40 cotton/polyester and 100 % polyester swatches were used as a sweat absorbing material in vests and T shirts. The In-vivo wear analysis was carried out with sedentary and non-sedentary workers. The worn samples were collected and subjectively analysed for the odour intensity after 24 hour storage at normal atmosphere. The subjective analysis result reveals that, highest amount odour intensity is in polyester. The intensity level in the following order: polyester>nylon>cotton/polyester>linen>viscose>cotton. Methanolic extract of Terminalia chebula was applied on the textile material to analyse the odour reduction ability. The subjective analysis results revealed that, the odour formation in the textile material reduced significantly after Terminalia chebula finishing process invariantly with fiber except nylon. To confirm the odour reduction objectively, bacterial isolation studies were performed with the treated and untreated worn samples. The results revealed that, the amount of bacterial colony in the finished textile reduced considerably than the worn untreated samples except nylon. Further, FTIR studies confirmed the reduction of odour forming short chain fatty acids in the treated worn textile than the untreated. Agar diffusion test results of finished textile, against major odour causing bacteria in axilla shows zone of inhibition up to 42 mm for all the fibers except nylon fabric. Hence, this study suggests a promising application of natural herbal finish for the odour reduction in apparels.

This study aimed to construct and validate the vision system for bacterial colony count on agar plates. The constructed vision system comprises of hardware components and software. The hardware components include a 4,000 lux light control box and a digital camera. The software was designed for user friendly operation, therefore; the interesting region can be selected; and threshold and colony diameter can be adjusted. Staphylococcus aureus, Escherichia coli and Bacillus cereus, important foodborne pathogens which possess different colony morphology were used for colony counting by the constructed vision system. The validation results revealed that the average percentage error was 2.13% in comparison to the counting by the expert. The constructed vision system has high precision and accuracy with a statistical significant. The Pearson correlation was 0.998 implying that the developed vision system has high performance for bacterial colony count. Thus this vision system is practically and economically for bacterial colony count in microbiological laboratories.

Bacterial colony classification is an important problem in microbiology. With the advances in computer-aided software's, similar problems have been solved in a speedy and accurate manner during the last decade. In this paper, deep neural network architecture will be presented to solve the bacterial colony classification problem. In addition, the training and testing strategy that relies on the strong use of data augmentation will be introduced. The used dataset was limited as it contains 660 images for 33 classes of a bacterial colony. Any neural network cannot learn from this data directly and in case of learning the neural network will overfit. The adopted training and testing strategy lead to a significant improvement in the training and testing phases. It raised the dataset images to 6,600 images for the training phase and 5,940 images for verification phase. The proposed neural network with the adopted augmentation techniques achieved 98.22% in testing accuracy. A comparative result is presented, and the testing accuracy was compared with those of other related works. The proposed architecture outperformed the other related works in terms of its testing accuracy.

To study the constrained emission/economic dispatch problem involving competing objectives in electric power systems with carbon capture system (CCS) technology, this paper proposes a multi-objective optimization approach based on bacterial colony chemotaxis (MOBCC) algorithm. In this algorithm, a Lamarckian constraint handling method based approach is improved to update the bacterial colony and the external archive. Finally, the optimization tests of the proposed algorithm are carried out in the IEEE 30-bus test system. Results demonstrate this approach has the advantage of dealing with highly non-linear and multi-objective functions of carbon capture thermal generator’s emission/economic dispatch problem.

A controlled trial of once daily cleaning of computer keyboards in an intensive care unit was performed comparing 2% chlorhexidine gluconate-70% isopropyl alcohol (CHG) and a chlorine dioxide-based product used as a standard in our hospital. A study before and after the introduction of once daily keyboard cleaning with CHG in the wider hospital was also completed. Cleaning with CHG showed a sustained and significant reduction in bacterial colony forming units compared with the chlorine dioxide-based product, demonstrating its unique advantage of maintaining continuous keyboard cleanliness over time.

Bacterial colony forming unit (CFU) counting is a tedious task mostly done by humans. Procedure is error prone, time-consuming and laborious. In this paper we present a semi-automatic prototype system for CFU counting. The developed prototype consist of a hardware (area scan camera with LED light source) and C#-based desktop application. The application enables manual, semi-automatic and automatic CFU counting. Automatic CFU counting is based on Hough transform for circles. Obtained results can be user-corrected for better accuracy. In the experimental analysis, the developed application is evaluated on the synthetic CFU images. The results include time and counting performance measurements compared with the manual count. The results show that semi-automatic counting procedure can save on average 45% of counting time compared to manual count with the same counting accuracy. The automatic CFU counting on average has precision of 97% and recall of 82%.

Background and study aims: Endoscopic retrograde cholangiopancreatography-related infections are of increasing global concern due to the emergence of multidrug-resistant bacteria such as carbapenem-resistant enterobacteriaceae (CRE), with bacterial biofilm production postulated as one cause of persistent infection from such virulent organisms. Because N-acetylcysteine (NAC) has been shown to possess antibacterial and biofilm-disruption properties, we aimed to evaluate if NAC would demonstrate clinical utility in reducing the colony forming units (CFU) at the elevator end of a duodenoscope, one of the hardest areas to clean. Patients and methods: This was a pilot study of 16 procedures involving the use of a duodenoscope. After use, the elevator tip of a duodenoscope was cultured and submerged for 30 minutes, either in 20 % NAC (200 mg/mL, intervention) or in sterile water (control). After 30 minutes, the elevator tip was re-cultured. Results: Submersion of the distal end of a duodenoscope in 20 % NAC (200 mg/mL) for 30 minutes resulted in a statistically significant reduction in bacterial colony forming units compared to control (average reduction 41.6 % vs 8.8 %, P = 0.001). There was no visible damage and no optical distortion to the duodenoscope after submersion in NAC. Conclusions: In summary, NAC may be a safe, simple, and useful adjunct to currently available methods of duodenoscope reprocessing. Further research may better define NAC’s role in duodenoscope reprocessing, either broadly or specifically after procedures suspected to produce a high risk of bacterial contamination (e. g. choledocholithiasis).

This work considers multiagent Self-Organizing Interval Bacterial Colony Evolution Algorithm—new global optimization technique which is a fusion of interval analysis and heuristic procedures and rules. This algorithm, imitates process of bacteria colony evolution and implements features of self-tuning and chaos control. The efficiency of this method is demonstrated on two applied problems: group interception (where a system of interceptors should be navigated to a system of targets) and satellite stabilization (rotational motion dampening).

biological procedures depend on an accurate count of the bacterial colonies and other organisms. In biomedical research and clinical diagnosis, there is a great need to quantify the amount of bacteria in the samples.This paper presents a simple and cost effective methodology for automatically counting the Bacterial Colonies (BC). The proposed methodology for automatic colony counter is based on digital image processing techniques. Proposed methodology is tested with different type of filter images. It is observed that the results obtained with the proposed counter were not significantly different from the manual counting.

Background Our group will be assessing in a randomized trial whether the use of alcohol-based hand rub (ABHR) to clean non-sterile gloved hands (instead of performing hand hygiene (HH) and changing gloves) for the WHO 5 Moments of HH during a single patient encounter is an efficient and effective practice. In preparation for this future study and in the absence of a well-established gold standard, this pilot study aimed to identify an effective glove-sampling method with the ability to detect a difference between our two study arms. Methods Healthcare workers (HCWs) entering Contact Precaution rooms were recruited and randomized into the intervention arm (HCWs directed to clean gloves with ABHR at each opportunity) or the usual care arm (HCWs behavior is silently recorded at each opportunity). In both arms, HCWs individual gloved hands were randomized then sampled, using both sponge stick and direct imprint methodology (Fig 1–2). The outcome of interest was total bacterial colony forming units (CFUs). A Wilcoxon rank-sum test was performed to compare the median distribution of CFUs recovered by each sampling method between study arms. Sampled gloved hands were also categorized by level of bacterial detection (0 CFUs vs. more than 0 CFUs). For each sampling method, the proportional difference between categories was analyzed using a Fisher exact test. Results 42 unique HCWs participated in the study (25 intervention, 17 usual care). For each HCW interaction an average of 3 HH moments were recorded. Using the direct imprint technique, the median CFUs in the intervention arm compared with the usual care arm were 2 vs. 31, P < 0.01. Using the sponge stick technique, the median CFUs were 1 vs. 6, P = 0.25. (Fig 3). Using the agar method, bacteria was detected on 16/25 (64%) of gloved hands in the intervention arm compared with 17/17 (100%) in the usual care arm (P < 0.05). Using the sponge-stick method, bacteria was detected 16/25 (64%) of gloved hands in the intervention arm and on 15/17 (88%) in the usual care arm (P = 0.15). Conclusion The direct imprint method is an effective method to discriminate between our intervention arms. In addition, this method is more affordable and less work-intensive in the lab and as a sampling method than the sponge-stick method. Disclosures A. D. Harris, CDC Epicenter Program: Grant Investigator, Grant recipient; K. A. Thom, AHRQ: Grant Investigator, Grant recipient

Reactive power compensation of distribution network is an important method to improve power quality and voltage stability, while reducing the power loss of the distribution network. In this paper the objective function is built to minimize all the costs which include power loss costs and investment of the dynamic reactive power compensation device divided into each year. The actual operation of the distribution network is simulated considering light, normal and heavy load operation conditions. Bacterial colony chemotaxis (BCC) algorithm is used to determine which nodes to install the compensation devices. The calculation of reactive power compensation is done with the back/forward sweep algorithm adapting to the radial distribution system. In order to compensate three different load conditions separately, the fixed part and the switching part of the dynamic reactive power compensation device are used. This method applies to 28-node system, the result demonstrates that the method is feasible and effective.

Objective: To determine the effect of face washing with soap and water and cleaning with povidone iodine and cetrimide/chlorhexidine gluconate (Savlon) on upper-lid bacteria. Design: Prospective, nonrandomized clinical trial. Participants: Eighty patients attending the Eye Clinic, University College Hospital, Ibadan, Nigeria. Methods: Eighty patients assigned to 4 groups had swabs of the upper eyelid skin taken before and after face wash with soap and water, and cleansing with Savlon and 5% povidone iodine. Specimens were cultured and Gram stained. Bacterial counts were carried out using standard techniques. Results: Face washing with soap and water increased the proportion of patients with bacterial isolates from 80.0% to 87.5%. The average colony count increased from 187.1 to 318.5 colony units per mL ( p = 0.02). Application of 5% povidone iodine without face washing with soap and water reduced the proportion of patients with bacterial isolates from 82.6% (mean count 196.5) to 28.6% (mean count 34.1) ( p = 0.001); in comparison, the application of 5% povidone iodine after face washing with soap and water reduced the proportion from 71.4% (mean count 133.9) to 40.0% (mean count 69.0) ( p = 0.01). Application of Savlon without face washing with soap and water reduced the proportion of patients with bacterial isolates from 100% (mean count 3 10.9) to 41.2% (mean count 19.8) ( p = 0.004) compared with the application after face washing, which reduced the proportion from 89.5% (mean count 240.3) to 41.2% (mean count 82.9) ( p = 0.02). Conclusions: Both povidone and Savlon are effective in reducing periocular bacteria in an African setting. Prior face washing with soap and water had no added benefit in reducing bacterial colony count.

OBJECTIVES:To determine the best urinary bacterial concentration to diagnose urine infections.METHODS:We studied a quantitative culture of paired urine samples from children that were promptly tested together after serial dilution. The initial diagnosis of urinary tract infection made from the result of the first urine culture and subsequently modified according to the second sample result, and then the ratio of their colony counts was considered. A total of 203 children (aged 2.0 weeks to 17.7 years) were screened for urine infection in a hospital setting.RESULTS:The 36 children who had a urinary tract infection, defined as having the same uropathogen in both urine samples at concentrations within 25-fold of each other, had a mean colony count of 1.7 × 107 colony-forming units/mL. Among the 167 children who did not have a urinary tract infection, 12 (7.2%) would have had a false-positive diagnosis made on the first sample, which was revealed because the second sample result was different (n = 7) or had a ≥25-fold different colony count (n = 5). Raising the threshold from 105 to 106 colony-forming units/mL reduces the false-positive rate 4.8%. If 2 samples are cultured, the false-positive rates fall to 3.6% and 0.6%, respectively. All 9 children (5.4% of those without a urinary tract infection) who had a mixed culture with ≥105 colony-forming units/mL of a uropathogen (heavy mixed growth) in the first sample had a urine infection excluded by the second sample result.CONCLUSION:The minimum urinary bacterial concentration that is used to diagnose a urine infection should be increased from ≥105 to ≥106 colony-forming units/mL, because that would reduce the false-positive rate from 7.2% to 4.8% if 1 sample was cultured and from 3.6% to 0.6% if 2 samples were cultured. Urine samples with heavy mixed growths should be considered contaminated.

The cultivated area devoted to rice crops (Oryza sativa) in Brazil has expanded in recent years, along with improvements in yield. This has prompted the continuous exchange of material from active germplasm banks between government breeding programs. When placed in a greenhouse for multiplication purposes, rice accessions resulting from exchanges between USDA-ARS (United States Department of Agriculture - Agricultural Research Service) showed little or no germination. The accessions were sent to the tissue culture laboratory of BAG-CNPAF (Embrapa National Rice and Bean Research Center) to recover embryos by aseptically removing the seed coat of 10 seeds from each accession. Bacterial colony growth concomitant to germination inhibition was observed in some accessions, from which four bacterial isolates were obtained. Made available in DSpace on 2017-12-26T23:23:54Z (GMT). No. of bitstreams: 1 CNPAF2018pdv102n1.pdf: 213919 bytes, checksum: c3d290b54a0663e654d67513d579c97c (MD5) Previous issue date: 2017-12-18 Disease notes.

The aim of this study was to determine if mechanical bowel preparation (MBP) influences the intramucosal bacterial colony count in the colon.Macroscopically normal colon mucosa was collected from 37 patients (20 with and 17 without MBP) who were undergoing elective colorectal surgery at three hospitals. The biopsies were processed and cultured in the same laboratory. Colony counts of the common pathogens Escherichia coli and Bacteroides as well as of total bacteria were conducted. The study groups were comparable with regard to age, gender, antibiotics use, diagnosis and type of resection.MBP did not influence the median colony count of E. coli, Bacteroides or total bacteria in our study.MBP did not affect the intramucosal bacterial count in this study. Further studies are suggested to confirm these findings.

INTRODUCTION Operating department staff are usually required to wear dedicated theatre shoes whilst in the theatre area but there is little evidence to support the beneficial use of theatre shoes. PATIENTS AND METHODS We performed a study to assess the level of bacterial contamination of theatre shoes at the beginning and end of a working day, and compared the results with outdoor footwear. RESULTS We found the presence of pathogenic bacterial species responsible for postoperative wound infection on all shoe groups, with outdoor shoes being the most heavily contaminated. Samples taken from theatre shoes at the end of duty were less contaminated than those taken at the beginning of the day with the greatest reduction being in the number of coagulase-negative staphylococcal species grown. Studies have demonstrated that floor bacteria may contribute up to 15% of airborne bacterial colony forming units in operating rooms. The pathogenic bacteria we isolated have also been demonstrated as contaminants in water droplets spilt onto sterile gloves after surgical scrubbing. CONCLUSIONS Theatre shoes and floors present a potential source for postoperative infection. A combination of dedicated theatre shoe use and a good floor washing protocol controls the level of shoe contamination by coagulase-negative staphylococci in particular. This finding is significant given the importance of staphylococcal species in postoperative wound infection.