Time-related changes in bacterial air contamination of sterile covered items in operating rooms: a systematic review and meta-analysis.

Is there a correlation between airborne bacterial load measured by volumetric air sampling and fluorescent particle counting?

196. Reducing bioburden in the operating room: manual cleaning and pulsed-xenon ultraviolet light disinfection produces significant reduction in colony forming units

There is no firm evidence that one type of hand antisepsis is better than another in reducing SSIs. Chlorhexidine gluconate scrubs may reduce the number of CFUs on hands compared with povidone iodine scrubs; however, the clinical relevance of this surrogate outcome is unclear. Alcohol rubs with additional antiseptic ingredients may reduce CFUs compared with aqueous scrubs. With regard to duration of hand antisepsis, a 3 minute initial scrub reduced CFUs on the hand compared with a 2 minute scrub, but this was very low quality evidence, and findings about a longer initial scrub and subsequent scrub durations are not consistent. It is unclear whether nail picks and brushes have a differential impact on the number of CFUs remaining on the hand. Generally, almost all evidence available to inform decisions about hand antisepsis approaches that were explored here were informed by low or very low quality evidence.

Bacterial airborne contamination in the operating room during surgery indicates an increased risk for surgical site infection. The conventional surveillance method for bacteria in the air is by air sampling, plating, and counting of colony-forming units (CFU). Particle countingmeasuresparticles in the air, typically in sizes of 1-20µm, and has been suggested as an alternative to CFU measurements. The primary aim was to investigate the correlation between the number of airborne CFU and particles during surgery. The secondary aim was to explore whether different ventilation settings influence the correlation between CFU and particles. The databases Cochrane, Embase, and Medline were searched for relevant publications. Due to the heterogeneity of the data, meta-analysis was not possible and a narrative analysis was performed instead. The review included 11 studies. Two of the studies (n=2) reported strong correlation between particles and CFU (Rp =0.76 and Rc =0.74). The remaining studies observed moderate correlation (n=3), low correlation (n=3), or no correlation (n=3). Based on the primary results from this study, ventilation attribution to distinguish the correlation between particles and CFU had no or little contribution. Due to the lack of convincing evidence of correlation and lack of high-quality studies performing measurements in a standardized way, the studies could not provide the necessary evidence that show that particle counting could be used as a substitution for conventional air bacterial assessment. Further studies are warranted to strengthen the conclusion.

Automated Counting of Colony Forming Units (CFU): Towards Standardization of the Measurement of Potency in Cord Blood Cell Therapy Products

1. Introduction Tuberculosis (TB), caused by Mycobacterium tuberculosis, remains a leading cause of death among infectious diseases worldwide. Latent tuberculosis infections (LTBI) contribute to the global burden of TB disease. TB preventive treatment (TPT) is a key intervention to achieve the End TB Strategy targets. The World Health Organization recommends LTBI treatment regimens, including 6 or 9 months of once-daily isoniazid (INH, H), 4 months of once-daily rifampin (RIF, R), 3 months of once-weekly rifapentine (RPT, P) plus INH (3HP), 3 months of once-daily RIF plus INH, or 1 month of daily RPT plus INH (1HP). Clinicians and individuals with LTBI may be reluctant to implement TPT due in part to concerns regarding adherence to the long treatment duration and drug toxicity of the currently recommended LTBI treatment regimens. Shorter, better-tolerated, and cost-effective TPT regimens are highly desirable. Rifapentine is a long-acting rifamycin, and rifamycin-based regimens are now the preferred LTBI treatment because they have similar or better efficacy and higher completion rates due to their shorter duration. Based on our experiences with TPT practice among Chinese people with silicosis, we found that the 3HP regimen was not well tolerated due to an unexpectedly high frequency of adverse events (AEs) (70.4%) and grade 3 or 4 AEs (7.9%), especially the high incidence of flu-like systemic drug reactions (SDRs) (10.8%).[1] This result is consistent with that of a contemporaneous clinical trial conducted among elderly Chinese individuals.[2] The high incidence of AEs contributed to a low completion rate of the 3HP regimen. Pharmacokinetic analysis in our trial revealed that the geometric mean Area Under the Curve from time zero to infinity (AUC0-inf) for rifapentine and its metabolite were over 2-fold and 1.6-fold greater, respectively than those observed in the TBTC and PREVENT TB studies.[1] Additionally, the geometric mean concentrations 24 hours after administration were also two-fold greater than those in the PREVENT TB study. Meanwhile, flu-like SDRs commonly occur in individuals receiving intermittent rifampin, usually following high doses.[3] Thus, we devised a novel one-month, thrice-weekly regimen consisting of INH plus RPT, referred to as the 1H3P3 regimen. The aim was to mitigate peak concentrations by reducing the single dose of medication and increasing the frequency of administration, thereby avoiding SDRs associated with intermittent dosing. We employed a murine LTBI model for the evaluation of the 1H3P3 regimen. Among the developed murine models, the Cornell and low-dose aerosol infection models represent two fundamental mouse models of LTBI.[4] However, the administration of anti-TB drugs during model establishment and the relatively high bacterial burden undermine their suitability for studying TPT regimens. Presently, the most prevalent murine model for assessing TPT regimens involves immunization with Bacillus Calmette-Guérin (BCG) or recombinant BCG (rBCG). This immunization enhances the immune-mediated containment of M. tuberculosis infection, yielding a stable paucibacillary infection status akin to human LTBI, independent of antituberculosis treatment.[4] In this study, we employed this model to assess the efficacy of a novel short-course 1H3P3 regimen. 2. Research presentation This study adhered to the ARRIVE reporting guidelines and received approval from the Animal Care and Use Committee of the Shanghai Public Health Clinical Center (approval number: 2018-JS027). Figure 1A illustrates the establishment and TPT schema of the murine LTBI model. Thirty female BALB/c mice (Charles River Laboratories, Beijing, China), aged 5 weeks, were utilized. The primary objective of this study was to observe the decrease in M. tuberculosis colony-forming units (CFU) count during treatment. Secondary objectives included assessing organ bacterial burden and lung histopathology 6 weeks after M. tuberculosis infection. To ensure randomization, five mice were assigned to the nonimmunized control group, while the remaining were immunized with rBCG. Of the 25 immunized mice, five were sacrificed before treatment initiation. Subsequently, 10 mice per arm were distributed to the 1H3P3 and sham control treatment groups. Within each treatment arm, five mice per subgroup were sacrificed at 2-week intervals or 4-week intervals after treatment. The sample size determination was based on prior research.[5] To detect 1.5 log10 differences in organ CFU counts with a standard deviation of 0.5, three mice per group were deemed necessary to achieve over 80% statistical power with a type I error rate of less than 5%. However, to account for potential loss of animals during the experiment, five mice per group were utilized.Figure 1: Establishment of a paucibacillary infection murine model and treatment efficacy of the 1H3P3 tuberculosis preventive treatment regimen. (A) Experimental schematic. (B) Colony-forming units counts of M. tuberculosis in the lungs and spleens. (C) Representative hematoxylin-eosin staining histological sections for lung pathology (upper panel at 10× and lower panel at 200× magnification) of rBCG-immunized mice (n = 3) and nonimmunized mice (n = 5) at 6 weeks after M. tuberculosis infection. Multiple granuloma-like lesions with numerous foamy macrophages are indicated with thin arrows. (D) CFU counts of M. tuberculosis in the lungs and spleens of 1H3P3-treated mice (2-week and 4-week posttreatment, both n = 5) and control mice (2-week and 4-week posttreatment, both n = 4) during treatment. Data are presented as the mean with standard deviation in (B) and as the median with interquartile range in (D). The unpaired Mann-Whitney test (B, D) was used to compare variables. *, P < 0.05. ATB: Active tuberculosis; CMC: Carboxylmethyl cellulose; LTBI: Latent tuberculosis infections.All mice were housed in a biosafety level 3 laboratory of Fudan University in individually ventilated cages with sterile corn cob for bedding. Up to five mice were housed per cage with access to food and water ad libitum. Room temperature was maintained at 22 to 24°C with a 12-hour light/dark cycle. All mice were sacrificed by intentional isoflurane overdose followed by cervical dislocation. A murine LTBI model was established as previously described.[5] The rBCG strain, which overexpresses Rv3425, was utilized as a stronger immunizing agent compared to BCG.[6] Cultured to log-phase, the rBCG strain was collected by centrifugation, washed twice with PBS, and resuspended. The suspension was adjusted to an optical density at 600 nm (OD600) of 1.3 (6 × 107 CFU/mL). Mice were subcutaneously immunized with 100 μL of rBCG inocula, equivalent to 6 × 106 CFU per mouse, while mice in the nonimmunized control group were injected with PBS instead. Six weeks after immunization, all mice were intranasally infected with 160 CFU of M. tuberculosis H37Rv, utilizing a 40 μL 5000-fold dilution of a log-phase culture with an OD600 of 0.8 (2 × 107 CFU/mL), prepared similarly to the rBCG inocula. After another 6 weeks, mice in both the nonimmunized control group and the immunized sacrifice cohort were euthanized to assess organ bacterial burden and lung histopathology. Chemotherapy was initiated in both treatment groups. Mice in the 1H3P3 group were treated thrice-weekly with a 100 μL drug solution containing INH (66.7 mg/kg) and RPT (7.5 mg/kg), doses equivalent to human doses of 6.67 mg/kg (400 mg/day) and 7.5 mg/kg (450 mg/day), respectively, administered by gavage.[7,8] Mice in the control group were treated with a 100 μL 0.5% sodium carboxymethyl cellulose solution by gavage, serving as a sham control. The drugs were formulated for oral administration as previously described.[7] Briefly, INH tablets (Shanghai Pharmaceuticals Sine, China) were ground into a fine powder, and RPT powder (Sichuan Medshine Pharmaceutical, China) was suspended in distilled water containing 0.5% (w/v) sodium carboxymethyl cellulose (Sigma-Aldrich, China). The drug formulations for the entire treatment duration were prepared based on an average BALB/c body mass of 20 g. The drug stocks were prepared weekly, stored at 4°C, and briefly sonicated prior to oral gavage. The efficacy of the treatment was evaluated based on organ M. tuberculosis CFU counts throughout the treatment process. To monitor the progression of paucibacillary infection, untreated mice, both rBCG-immunized and nonimmunized, were sacrificed to establish baseline organ bacterial burden and assess lung histopathology. Lung and spleen homogenates were serially diluted and plated in duplicate on selective Middlebrook 7H10 agar for bacterial quantification. Lung tissue sections were stained with hematoxylin and eosin for histopathological examination. During the anesthesia process before M. tuberculosis challenge, two mice from the immunized group and two from the sham control group accidentally died. Thus, our final analysis included 26 mice. While researchers were aware of group allocation throughout the experiment, they were blinded during outcome assessment. The CFU counts (x) underwent a logarithmic transformation as log10 (x + 1) and were compared between treatment groups using the unpaired Mann-Whitney U test. All statistical analyses were conducted using GraphPad Prism 8 software (GraphPad Software, San Diego, CA, USA). A significance level of P < 0.05 was applied. Figure 1B illustrates that at week 6 after M. tuberculosis challenge, the mean bacterial burdens in the lungs and spleens of rBCG-immunized mice were 3.75 ± 0.12 and 3.18 ± 0.53 log10 CFU/g, respectively, significantly lower than those of the nonimmunized mice (5.49 ± 0.40 and 4.30 ± 0.29 log10 CFU/g). A histopathological examination of the lungs revealed distinct differences between rBCG-immunized and nonimmunized mice (Fig. 1C). Multiple granuloma-like lesions, surrounded by numerous foamy macrophages, were observed in the lungs of the nonimmunized mice. In contrast, rBCG-immunized mice exhibited only scattered lesions of disorganized granulomas and lower levels of inflammation in the perivascular and peribronchiolar areas. The efficacy of treatment was evaluated by measuring M. tuberculosis CFU counts at 2 and 4 weeks after treatment (Fig. 1D). Following 2 weeks of treatment, the median bacterial burden in the lungs of mice treated with 1H3P3 decreased to 0 (0, 1.56) log10 CFU/g, which is a significant reduction compared to baseline (3.73 [3.64, 3.88] log10 CFU/g, P < 0.05). After 4 weeks of treatment, the 1H3P3 regimen resulted in all treated mice being culture-negative, except for one mouse with only 5 CFU in the lungs. In the spleen, the median CFU count decreased to 0 (0, 1.75) log10 CFU/g at 2 weeks after treatment, also significantly lower than baseline (2.93 [2.83, 3.79] log10 CFU/g, P < 0.05). Ultimately, the spleen M. tuberculosis burden was eradicated in all mice treated with 1H3P3 by the end of the treatment period. In contrast, all mice in the control group remained culture-positive at week 4, with a median bacterial burden of 1.71 (0, 3.46) and 3.45 (2.82, 3.61) log10 CFU/g in the lungs and spleens, respectively. There was no significant difference in CFU counts between weeks 4 and 0 in the control mice (both P > 0.05). 3. Discussion In this study, we evaluated the treatment efficacy of a novel 1-month thrice-weekly INH-RPT regimen in a murine model of LTBI. Our findings demonstrate the potent bactericidal activity of the 1H3P3 regimen against M. tuberculosis within a 4-week timeframe. Over the past two decades, various regimens for TPT have undergone development and evaluation in murine models of LTBI. RPT has emerged as a particularly promising alternative to RIF in LTBI treatment. Direct dose-ranging comparisons have revealed that RPT exhibits roughly four times higher potency than RIF.[9] Moreover, results from multiple clinical trials on TPT support the superior efficacy of RPT-based regimens for LTBI treatment.[10] With the incorporation of RPT, our 1H3P3 regimen also demonstrated potent bactericidal activity, achieving culture-negative status in all mice within 4 weeks, except for one mouse with only five CFU in the lungs. Previous studies have indicated that daily RPT + INH treatment can reduce lung bacterial load by 2.4 log10 CFU within 2 weeks, whereas weekly RPT + INH requires 4 weeks to achieve a reduction of approximately 1.5 log10 CFU in lung bacterial load.[5] This suggests that our thrice-weekly RPT-based regimen exhibits effective activity similar to existing daily and weekly RPT + INH regimens. Specifically, the 1H3P3 treatment rapidly decreased organ bacterial load by approximately 3 log10 CFU within 2 weeks. Future studies should include a comparison of this novel 1H3P3 regimen with existing daily INH + RPT regimens, along with an assessment of relapse rates. Currently, there exists a significant shortage of RPT in the global supply market, constraining the adoption of 3HP and 1HP regimens. The dosage of RPT in our innovative 1H3P3 regimen has been reduced, potentially offering superior cost-effectiveness and accessibility. Compared with the daily RPT-based regimen, intermittent administration of RPT is preferable due to its long-acting nature. In China, the recommended dosage for patients with TB is only 600 mg twice weekly. Therefore, our 1H3P3 regimen would facilitate the adoption of the intermittent rifapentine regimen, aligning with the recommended dosing, making it more feasible in China than the daily rifapentine regimen. These advantages underscore the necessity for further assessment of this novel TPT regimen in real-world settings. The current study exhibits certain limitations. Because of constraints imposed by the experimental conditions, we were unable to evaluate the burden of organ bacilli 3- to 6-months posttreatment completion in mice treated with 1H3P3. Consequently, our findings offer evidence supporting the robust bactericidal activity of the 1H3P3 regimen. However, further assessment is required to determine its efficacy in preventing LTBI relapse. Additionally, during sham treatment, spontaneous bacterial clearance was observed in the selected organs of three mice, possibly attributable to the immunotherapeutic effect of rBCG vaccination. Nevertheless, these mice failed to completely eradicate M. tuberculosis, with the bacterial load in their culture-positive organs remaining high, comparable to that in untreated mice. In contrast, all 1H3P3-treated mice were culture-negative at treatment completion, except for one with a low CFU count in the lungs. Thus, these results affirm the potent bactericidal activity of the 1H3P3 regimen, suggesting that the eradication of M. tuberculosis infection in these mice was unlikely solely due to the host immune response. Furthermore, in addition to treatment efficacy, the presence of RPT drug carryover should be considered when interpreting negative or low-organ CFU readouts in 1H3P3-treated mice, because of the absence of charcoal in 7H10 agar plates. In conclusion, the 1H3P3 regimen demonstrated potent bactericidal activity, rapidly reducing the burden of M. tuberculosis in a murine model of LTBI within 12 doses. Our findings underscore the potential of this novel short-course 1H3P3 regimen as a candidate for LTBI treatment and advocate for its further evaluation in future preclinical and clinical studies.

Background: Hand hygiene is a fundamental measure in preventing nosocomial infections; however, compliance with recommended protocols varies, and the effectiveness of different hand hygiene methods remains a topic of ongoing research. This study evaluates the impact of two distinct hand hygiene protocols – standard handwashing with soap and water versus alcohol-based hand rub (ABHR) combined with structured training -on bacterial contamination levels among healthcare workers. Methods: A quasi-experimental study was conducted with 60 healthcare workers, divided into a Control Group (CG, n=30) and an Experimental Group (EG, n=30). Bacterial contamination was assessed through colony-forming unit (CFU) counts before and after hand hygiene procedures. The CG followed routine handwashing, while the EG used ABHR and received structured hand hygiene training. Bacterial reduction was analyzed using paired and independent t-tests. Results: The CG demonstrated a 50.4% reduction in CFU counts after handwashing, but 20% of participants retained contamination levels above 100 CFU. In contrast, the EG achieved a significantly greater 85.9% reduction in bacterial load, with 26.7% of participants achieving complete bacterial elimination (p&lt;0.001). The absolute mean CFU reduction in the EG (144.5±21.3 CFU) was significantly higher than in the CG (83.5±18.6 CFU). Conclusion: The findings confirm that ABHR combined with structured training is significantly more effective in reducing bacterial contamination compared to traditional handwashing. These results align with existing literature supporting the prioritization of ABHR in hospital settings. The study underscores the necessity of ongoing training and compliance monitoring to enhance hand hygiene effectiveness and minimize healthcare-associated infections.

Aim This study evaluates the effectiveness of preprocedural mouth rinsing when performing non-surgical periodontal prophylaxis to reduce bacterial aerosol contamination.Data sources The authors used the population, intervention, control and outcomes (PICO) question format to perform a systematic online search in Scopus, PubMed, Cochrane Library and Web of Science. All the databases were explored with no time limit until April 2020.Study selection Randomised clinical trials were included in this systematic review. No inclusion or exclusion criteria are mentioned in this study and it is limited to bacterial contamination studies.Data extraction and synthesis The authors extracted the following information from the included studies: authors; article publication year; study design; sampling size and allocation of test and control groups; intervention details; type and description of periodontal prophylaxis procedures; and primary outcomes. They focused on statistically significant findings and the reduction of bacterial aerosol contamination between groups was measured by colony forming units (CFU) using means and percentages. The primary outcome was that bacterial count expressed as CFU on blood agar plates. If permissible, they calculated the mean CFU reduction in the included studies and reported them. The authors also assessed the studies' risk of bias using the revised Cochrane risk of bias tool for randomised trials.Results In total, 30 randomised controlled trials were included, 21 of which assessed the preprocedural rinsing and the remaining nine focused on other interventions. The bacterial incubation protocol differed among studies. The data collection sites differed among the studies in terms of the number of samples obtained, position, direction and distance from the subjects' mouths. There were no marked differences in the CFU reduction regarding the periodontal prophylaxis devices used and the location of aerosol sampling collection from these studies. Nearly half of the studies (52.4%, 11/21) collected the sample at or near the operator and dental assistant. Chlorhexidine (CHX) rinse was mostly tested (80.9%, 17/21) with various concentrations and volumes. Among studies comparing CHX with other agents (71.4%, 15/21), CHX was more effective for the better part of studies, with more than half of the studies (7/15) reporting over a 70% reduction in CFU when using CHX preprocedural mouth rinse.Conclusions Evidence corroborates the effectiveness of preprocedural mouth rinses, especially CHX, in reducing the bacterial contamination of aerosols in periodontal, non-surgical prophylaxis compared with mouth rinsing with water, or with no rinsing. Nevertheless, the low-quality of evidence and the high heterogeneity among the included studies warn that one should be cautious in generalising the findings of this study to other settings and contaminating agents, like viruses. The findings of this study emphasise the need for more studies on the efficacy and effectiveness of preprocedural rinses in reducing the viral load in aerosols (and droplets) during periodontal prophylaxis procedures.

Liaison: Anthony T Tokarski BS Leaders: David Blaha MD (US), Michael A. Mont MD (US), Parag Sancheti MS, DNB, MCh (International) Delegates: Lyssette Cardona MD, MPH, MHA, AAHIVS, FIDSA, Gilberto Lara Cotacio MD, Mark Froimson MD, Bhaveen Kapadia MD, James Kuderna MD, PhD, Juan Carlos Lopez MD, Wadih Y Matar MD, MSc, FRCSC, Joseph McCarthy MD, Rhidian Morgan-Jones MB BCh, FRCS, Michael Patzakis MD, Ran Schwarzkopf MD, Gholam Hossain Shahcheraghi MD, Xifu Shang MD, Petri Virolainen MD, PhD, Montri D. Wongworawat MD, Adolph Yates Jr, MD

INTRODUCTION: Dropping the free bone flap on the operating room floor during a neurosurgical procedure is a rare and poorly documented accident. In fact, it has been reported in up to 3 out of 1000 operations involving craniotomies. The literature guiding its management is insufficient: to date, there is no protocol for sterilization of an accidentally contaminated flap in order to reposition it safely on the patient's skull. METHODS: Cadaveric human bone flaps were collected and intentionally dropped onto the floor of a neurosurgical operating room. Bacterial contamination from these flaps was quantified in colony forming units (CFU) counted on culture plates inoculated with the fragments. Identified species were included in a mixed preparation of microorganisms used to artificially contaminate fragments from 29 other individual flaps in a standardized manner. All 29 contaminated flaps were previously cut into five pieces and the following five sterilization protocols were completed on a fragment per flap each: rinsing with saline, mechanical debridement with sterile gauze, rinsing with antibiotics, rinsing with alcoholic chlorhexidine and flash sterilization by autoclave. Decontamination was measured by inoculation onto culture plates and CFU count. RESULTS: The observed contamination from a flap dropped on an operating room floor can be significant (up to 120 CFU cultured per flap). All protocols tested decreased bacterial load of the bone flaps to different degrees: saline by 95.7%, mechanical debridement by 97.6%, antibiotic bath by 99.5%, alcoholic chlorhexidine by 99.9% and flash sterilization by 100.0%. CONCLUSIONS: In the event of the accidental fall of a bone flap, decontamination by rinsing in an alcohol-chlorhexidine solution, which seems to represent the best combination of effectiveness versus the risks and the complexity of the method, could be considered.

Post-Thaw Colony Forming Unit (CFU) Counts and Yield Are the Most Important Predictors of Engraftment and Survival Following Unrelated Donor Cord Blood Transplantation (CBT): A COBLT Study Report.

INTRODUCTION: Small Intestinal Bacterial Overgrowth (SIBO) is associated with abnormally high bacterial counts in the small intestine and clinical features such as diarrhea, constipation, abdominal pain, distension and bloating. A meta-analysis of studies of endoscopic samples from patients with suspected SIBO was performed to estimate the distribution of bacterial colony forming units (CFU) and identify the bacterial populations in these patients. METHODS: A literature search was performed to find studies of the jejunum or duodenum culture aspirates from patients with suspected SIBO using keywords: SIBO (or SBBO), culture aspirate and CFU. A total of 10 studies met the inclusion criteria. The CFU distribution was estimated using a log-spline smoothing technique in the statistical package R. Top bacterial population identified in aspirates of these patients was reviewed. RESULTS: The studies used in the meta-analysis including the number and type of subjects, the region where the culture aspirate sample was taken, and the type of CFU data presented was summarized in Table 1. A histogram of the estimated CFU distribution using the first five papers with actual CFU counts was shown in Figure 1. The spike at zero showed that approximately 26% of patients had sterile cultures. Sensitivity analyses using the first seven papers and all ten papers yielded similar estimated distributions to Figure 1, particularly in terms of the proportion of subjects with CFU counts between 104 and 106. The proportion of subjects in the tails of the distributions (sterile samples or CFU counts &gt;1010) had larger variations between the three fitted distributions presumably due to differences in counting methodologies. The top bacterial species cultured and identified from jejunal aspirates was summarized in Table 2. CONCLUSION: Using a standard diagnostic threshold &gt;105 CFU, only 24% of patients with suspected SIBO would test positive; while lowering the threshold to &gt;104 CFU increases the positive call rate to 33%. As expected, bacterial culture identification was unable to clearly distinguish a single contributing organism. Limitations to this work are substantial and include variability in sampling regions, contamination, difficulty culturing and counting bacteria, lack of standardization in procedures and reproducibility. Given these limitations, there is consensus that novel tools are needed for evaluating patients with suspected SIBO.

We found no studies that evaluated disease transmission via aerosols in a dental setting; and no evidence about viral contamination in aerosols. All of the included studies measured bacterial contamination using colony-forming units. There appeared to be some benefit from the interventions evaluated but the available evidence is very low certainty so we are unable to draw reliable conclusions. We did not find any studies on methods such as ventilation, ionization, ozonisation, UV light and fogging. Studies are needed that measure contamination in aerosols, size distribution of aerosols and infection transmission risk for respiratory diseases such as COVID-19 in dental patients and staff.

Background The effect of the number of door openings in the operating room (OR) on surgical site infections (SSI) risk remains a controversial topic. Many SSI prevention bundles include a restriction on the maximum number of door openings as intervention, often to ten per hour. However, existing evidence is limited and heterogeneous. This individual participant data (IPD) meta-analysis aims to evaluate the effect of the number of door openings in the OR on SSI occurrence. Methods We searched MEDLINE (Pubmed) and Embase (Ovid) up to 15 January 2024, for studies investigating the effect of the number of door openings on SSI incidence. Authors of eligible studies were invited to collaborate. IPD were merged and analysed with a logistic regression model with mixed-effects. This study is registered with PROSPERO, CRD42022309958. Findings IPD from eight observational studies, encompassing 4412 patients, revealed a 6.0% overall SSI incidence. The logistic regression model with mixed-effects indicated a difference in SSI risk for each extra door opening per hour (OR 1.01 [95% c.i. 1.004–1.02]; very low certainty of evidence). To enhance the practical applicability, door openings were categorised. Inconclusive evidence was found regarding SSI risk difference for 10 to 31.7 door openings per hour (OR 1.11 [95% c.i. 0.77–1.59]) compared to 10 or fewer. While for more than 31.7 door openings per hour (OR 1.52 [95% c.i. 1.02–2.26]) a conclusive difference in SSI risk was found compared to 10 or fewer. Interpretation Very low certainty of evidence indicated a marginal increase in SSI risk for each extra door opening per hour. However, a restriction on the number of door openings in the OR to a maximum of 10 per hour has little to no effect on SSI risk. Funding This systematic review is funded by the Dutch Stichting Kwaliteitsgelden Medisch Specialisten (SKMS, Foundation Quality Funds Medical Specialists).

This study was carried out to evaluate the quality of raw milk measured by Standard Plate Count (SPC). Individual raw milk for the Colony Forming Units (CFU) study was carried out in the National Cattle Research Program Rampur Chitwan, Nepal. Milk from Jersey and Holstein cows with two types of milking (hand and machine milking) in collecting three types of containers (Plastic, aluminum, and steel). Milk had different chilling durations (0, 4, 8, 12, 24, 48, and 72 hours). Altogether, 252 milk samples for SPC were examined at farm levels. Results showed significant variability in SPC throughout the study period. The lowest CFU was observed in Holstein cows (80.49±4.83 × 104), while the highest was found in the Jersey breed (122.88±4.69 × 104). Similarly, the lowest CFU count was recorded in milk from machine milking (92.42±4.69 × 104), whereas the highest CFU count was observed in milk from hand milking (110.95±4.83 × 104). For three milk collecting and transporting containers, the CFU count was lowest in the steel container (90.09±5.82×104) compared to the aluminum container (102.42±5.82×104) and plastic container (112.55±5.82×104). The results of mean CFU for the chilling duration effects at farm 0, 4, 8,12,24,48 and 72 hours were (114.33±8.11×104, 108.21±10.28×104, 107.71±10.28×104, 106.75±10.28 ×104, 104.07±6.36 ×104, 94.79±8.11×104, and 75.94±8.11×104). CFU count in hand and machine milking milk differed significantly (p&lt;0.01) from each record of the same date at the farm level. The CFU in milk from different containers was significant (p&lt;0.05) for the overall experimental period. Steel containers showed a low CFU count compared to Aluminum and plastic containers. The highest number of CFU (114.33×104) was observed in the 0-hour chilling, which was significantly (p &lt;0.05) different from the rest of the chilling duration. The results obtained from the study indicated that the current situation is critical and needs real improvement from farm to chilling centers. The findings could guide dairy producers in adopting effective strategies to enhance milk quality, minimize bacterial contamination, and ensure safer dairy products for consumers by using these results.