Examination of bacteria/host cell interactions is important for understanding the aetiology of many infectious diseases. The colony forming unit (CFU) has been the standard for quantifying bacterial burden for the past century, however, this suffers from low sensitivity and is dependent on bacterial culturability in vitro. Our data demonstrate the discrepancy between the CFU and bacterial genome copy number in an osteomyelitis-relevant co-culture system and we confirm diagnosis and quantify bacterial load in clinical bone specimens. This study provides an improved workflow for the quantification of bacterial burden in such cases.

Introduction The phenomenon of coronavirus disease 2019 (COVID-19)-related candidiasis is gaining increased attention and acknowledgment as an integral component of the severe consequences of COVID-19. The aim of the present study was to assess the association between Candida albicans and COVID-19 in complete denture wearers. Materials and methods An observational study was conducted on 45 complete denture wearers, who were divided into three groups as follows: Group 1, 15 subjects with mild to moderate COVID-19 infection; Group 2, 15 subjects with severe COVID-19 infection; and Group 3, 15 subjects without COVID-19 infection. Mean colony forming units (CFU) were observed on agar plates containing Sabouraud dextrose in the salivary samples of the participants. Analysis of variance, followed by post-hoc analysis by Tukey\'s test, was used to compare CFU between the groups. Pearson\'s correlation coefficient was used to study the correlation between variables. Results The highest average colony-forming units of Candida albicans were observed in Group 2, followed by Group 1, compared to the control group, and a significant (p<0.001) difference was found. A weak positive correlation was found between the age of the patients and the duration of denture usage, as well as between age and the counts of Candida albicans in Groups 1 and 3. This correlation was more pronounced in Group 3. A strong positive correlation was observed in all groups between the Candida albicans count and the duration of denture usage by the patients. Conclusion The association between Candida albicans and denture wear was compounded by the presence of COVID-19. Consequently, the timely identification of Candida albicans infection in patients with COVID-19 is important to establish more efficacious approaches for antifungal treatment and prophylactic interventions.

Enumeration of bacteriophages by plaque assay requires the mixing of host-specific bacteria with a lytic bacteriophage of interest in a soft agar overlay (top agar) to prevent the spread of viral infection in the medium; the mixture is then spread on a solid bottom agar. An infection of a single lytic phage particle with a bacterium results in the lysis of the host bacterium and the release of new phage progeny. The new phage progeny released from each bacterium will infect/lyse neighboring bacteria to form a \"plaque,\" which is a clear visible area (that can be counted) with the naked eye. If phages are not present in the mixture, the host bacterium will form a \"lawn\" in the soft agar overlay and grow to a stationary phase.

UNASSIGNED: This study investigated the number of bacterial colonies in four types of suture threads, including silk, nylon, monocryl, and monocryl plus after periodontal surgery in patients with moderate-to-severe periodontitis.
UNASSIGNED: In this single-blind randomized clinical trial, a total of 12 patients with periodontitis who required periodontal flap surgery in all quadrants were included. One type of suture, either silk, nylon, monocryl, or monocryl plus (coated with triclosan), was used following each surgery in each quadrant. Sutures (3 mm) were removed from the mid, posterior, and anterior regions of the flap 7 days postoperatively, and placed in a tube-containing buffer medium to transfer to the culture medium in a laboratory. Then, the bacterial colonies on each culture medium were counted manually. Finally, the mean number of grown colonies (anaerobic and aerobic) was computed and compared in each group of sutures. Data were analyzed by SPSS (Version 20) using the repeated measures ANOVA and least significant difference follow-up tests (α = 0.05).
UNASSIGNED: The findings of this study indicated a significantly higher mean number of aerobic, anaerobic, and aerobic-anaerobic colonies in silk suture than in the other three types of sutures (P < 0.05). However, no significant difference was observed among other types of sutures (P > 0.05).
UNASSIGNED: The results of this study showed that silk suture had a higher bacterial adhesion (aerobic, anaerobic, and aerobic-anaerobic) than monofilament sutures, including nylon, monocryl, and monocryl plus. Moreover, no significant difference was found among the monofilament sutures in the number of colonies grown on them.

We systematically investigate functional and molecular measures of stemness in patients with acute myeloid leukemia (AML) using a cohort of 121 individuals. We confirm that the presence of leukemic stem cells (LSCs) detected through in vivo xenograft transplantation is associated with poor survival. However, the measurement of leukemic progenitor cells (LPCs) through in vitro colony-forming assays provides an even stronger predictor of overall and event-free survival. LPCs not only capture patient-specific mutations but also retain serial re-plating ability, demonstrating their biological relevance. Notably, LPC content represents an independent prognostic factor in multivariate analyses including clinical guidelines of risk stratification. Our findings suggest that LPCs provide a robust functional measure of AML, enabling quantitative and rapid assessment of a wide range of patients. This highlights the potential of LPCs as a valuable prognostic factor in AML management.

BACKGROUND: In order to improve the biological control agent (BCA) efficacy, stress factors threatening the viability of microorganisms during spray application need to be determined. The effect of spray mixture temperature and exposure time on Trichoderma harzianum T 22 and Bacillus amyloliquefaciens QST713 viability were tested. Concurrently the combined effect of mechanical and thermal stress effect on BCA viability were tested at two initial spray mixture temperatures (14 and 25 °C) by simulating a spray application using airblast sprayers featured by different tank capacity and a spray liquid circuit (without and with hydraulic agitation system). To assess the BCA microorganism viability, spray mixture samples were collected at time intervals along trials and plated to count the colony forming units (CFU).
RESULTS: The critical temperature threshold that inhibited BCA viability was 35 °C with 30 min of exposure. The sprayer type, the initial temperature of the spray mixture and the temperature increment during the trials significantly decreased the number of CFU recovered. When simulating a spray application, the spray mixture temperature increase rate was determined mainly by the residual amount of spray mixture in the tank. Even if the tank capacity does not substantially affect the final temperature reached by the spray mixture, the higher residual spray mixture in bigger tanks can expose the BCAs for a longer time to critical temperatures.
CONCLUSIONS: Experimental trials allowed us to identify the effect of factors affecting the viability of tested BCAs, providing information about the actual chance to guarantee the biological efficacy of BCA treatments. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Dental polymers are now available as monolithic materials which can be readily used in computer-aided design and computer-aided manufacturing (CAD/CAM) systems. Despite possessing numerous advantages over conventionally produced polymers, the polymers produced by either of these systems fail to exhibit immunity to surface microbial adhesion when introduced into the oral environment, leading to the development of oral diseases. The aim of this study was to analyze the biofilm formation of six microorganisms from the oral cavity and its correlation to the surface characteristics of CAD/CAM dental polymers. A total of ninety specimens were divided into three groups: resin-based composite, polymethyl methacrylate, and polyether ether ketone. The experimental procedure included surface roughness and water contact angle measurements, colony forming unit counting, and scanning electron microscopy analysis of biofilm formed on the surface of the tested materials. The data were analyzed using the Kruskal-Wallis test, with a Dunn\'s post hoc analysis, and one way analysis of variance, with a Tukey\'s post hoc test; the correlation between the measurements was tested using Spearman\'s correlation coefficient, and descriptive statistics were used to present the data. Despite using the same manufacturing procedure, as well as the identical manufacturer\'s finishing and polishing protocols, CAD/CAM dental polymers revealed significant differences in surface roughness and water contact angle, and the increased values of both parameters led to an increase in biofilm formation on the surface of the materials. The CAD/CAM resin-based composite showed the lowest number of adhered microorganisms compared to CAD/CAM polymethyl methacrylate and CAD/CAM polyether ether ketone.

For enumerating viable bacteria, traditional dilution plating to count colony forming units (CFUs) has always been the preferred method in microbiology owing to its simplicity, albeit being laborious and time-consuming. Similar CFU counts can be obtained by quantifying growing micro-colonies in conjunction with the benefits of a microscope. Here, we employed a simple method of five to ten microliter spotting of a diluted bacterial culture multiple times on a single Petri dish followed by determining CFU by counting micro-colonies using a phase-contrast microscope. In this method, the CFU of an Escherichia coli culture can be estimated within a four-hour period after spotting. Further, within a ten-hour period after spotting, CFU in a culture of Ralstonia solanacearum, a bacterium with a generation time of around 2 h, can be estimated. The CFU number determined by micro-colonies observed for 106-fold dilutions or lower is similar to that obtained by the dilution plating method for 107-fold dilutions or lower. Micro-colony numbers observed in the early hours of growth (2 h in case of E. coli and 8 h in case of R. solanacearum) were found to remain consistent at later hours (4 h in case of E. coli and 10 h in case of R. solanacearum), where the visibility of the colonies was better due to a noticeable increase in the size of the colonies. This suggested that micro-colonies observed in the early hours indeed represent the bacterial number in the culture. Practical applications to this counting method were employed in studying the rifampicin-resistant mutation rate as well as performing a fluctuation test in E. coli. The spotting method described here to enumerate bacterial CFU results in reduction of labour, time and resources.

The aim of the study was to investigate the adhesion and viability of Streptococcus oralis and Candida albicans under in vitro conditions on CAD/CAM framework materials for implant-supported hybrid prostheses. Twenty-nine specimens were prepared from each of three different materials: ZR (zirconia), PEEK (polyether ether ketone) and CoCr4 (CoCr4 alloy). The experimental part included surface roughness (SR) and contact angle of water (CAW) measurements, followed by colony forming unit (CFU), cell viability assay and scanning electron microscopy (SEM) analyses of Strep. oralis and C. albicans biofilms on the materials\' surfaces. Kruskal-Wallis and one-way analysis of variance (ANOVA) tests were used for differences between materials, and the correlation between measurements was estimated using Spearman\'s correlation coefficient. PEEK specimens revealed higher SR, CAW and CFU mean values, than ZR and CoCr4 specimens. Strong positive correlation was found between SR and CFU and between CAW and CFU for both microbial species. Cell viability assay revealed similar values for both species across materials. Higher numbers of Strep. oralis and C. albicans on PEEK specimens confirm the impact of the higher surface roughness and contact angle values on the microbial adhesion and describes PEEK as less desirable than ZR and CoCr4 from microbiological aspect.

Over 50 years have passed since discovering mesenchymal stromal cells (MSCs). Initially, despite gaps in the knowledge of the identity of these cells, their therapeutic aspects were recognized. Consequently, MSCs became candidates for treating a wide range of diseases. However, the therapeutic effects of MSCs are not stable in the long term, and there are inconsistent data on their clinical efficacy. Even though more than 1000 MSC-based clinical trials have been registered, and the safety of MSCbased cell therapies has been proven, data on the clinical efficacy of MSCs have not been enough to warrant FDA approval for clinical treatment and marketing purposes. The available information on MSCs still contains some controversies, perhaps owing to little progress in understanding their in vivo identity. MSCs have been used for therapeutic purposes despite poor knowledge of their in vivo origin or functions. Hence, perhaps we need to go back to the basics of MSCs and spend more time understanding the biology of these cells. An improved understanding of MSCs\' location and function within tissues may improve their therapeutic efficacy and, consequently, their establishment as a cell therapy product.