Magnetic resonance imaging presentation of prostatic stromal sarcoma.

Prostatic stromal sarcoma (PSS) is a rare malignant tumor that often occurs in young people. Despite the fact that their clinical pathological characteristics are well known, our understanding of the imaging characteristics still seems to be limited. In our search of the literature, PSS articles are mainly present as case reports. In this case series of PSS, we aimed to thoroughly describe the magnetic resonance imaging (MRI) features, histopathological findings, and distinguishing hallmarks from prostate cancer (PCA).

Blunt esophageal injury in the setting of multitrauma: A case report.

Blunt esophageal injury is an unusual organ injury that has unclear clinical symptoms due to the overlap of thoracoabdominal trauma in the setting of multiple traumas. The treatment options vary depending on the patient's clinical symptoms, the extent of esophageal damage, and the time from the onset of damage to diagnosis. This article presents a case of a young male patient receiving emergency treatment after a traffic accident. Esophageal perforation was diagnosed through chest computed tomography with contrast injection and oral contrast. The article focuses on imaging characteristics and suggestive signs of blunt esophageal injury in the setting of multitrauma.

Increase in temperature facilitates Campylobacter jejuni biofilm formation under both aerobic and microaerobic incubation.

The formation of Campylobacter jeuni biofilms on processing surfaces is a significant concern in poultry processing, contributing to food safety risks. This study focused on assessing the biofilm forming capabilities of 12 field isolates of C. jejuni of different aerotolerance categories on stainless steel surfaces, a prevalent material in poultry processing environments. Working cultures of each isolate were prepared to approximately 6 log CFU/mL and incubated on stainless steel coupons under microaerobic or aerobic conditions at room temperature or 42°C for 72 h. Biofilm attached cells were enumerated using direct plating and biofilm density was measured using a crystal violet assay by measuring the optical density (OD600) a. Data analysis was conducted using the PROC GLIMMIX procedure in SAS 9.4 with a significance level of 0.05. The study revealed a notable interaction between aerotolerance categories and temperature (P < 0.039) impacting the number of biofilms attached C. jejuni cells on stainless steel coupons. All isolates had significantly higher counts when incubated at 42°C compared to room temperature, regardless of oxygen level (P < 0.001). Furthermore, stronger biofilm density was observed at 42°C compared to room temperature, regardless of oxygen level. These findings underscore the influence of temperature on the biofilm forming ability of C. jejuni. The ability of these field isolates to form biofilms under various environmental conditions suggests a heightened potential for surface colonization and increased infection risk in poultry processing facilities.

A Bibliometric Analysis of Scientific Publications on Eating Disorder Prevention in the Past Three Decades.

BACKGROUND: Eating disorders (EDs) present a growing concern due to their widespread occurrence and chronic course, the low access to evidence-based treatment, and the significant burden they place on the patients and society. This picture justifies intensive focus on the prevention of EDs. The current study provides the first bibliometric analysis of research on the prevention of EDs, focusing on trends and contributions, to prompt further prevention research. METHODS: We conducted a bibliometric analysis of publications on the prevention of EDs using the Web of Science database, from 1993 to 2023. Focusing on universal and selective prevention strategies, our study involved a rigorous selection process, narrowing down from 10,546 to 383 relevant papers through manual screening. The analysis utilized the "bibliometrix" R package (version 4.2.2) and Python (version 3.9.6) for data processing, with VOSviewer employed for mapping collaboration networks. RESULTS: Our analysis revealed a consistent annual growth rate of 10.85% in ED prevention research publications, with significant contributions from the "International Journal of Eating Disorders" and some notable authors. The United States emerged as the dominant contributor. The analysis also highlighted key trends, including a surge in publications between 2010 and 2017, and the role of major institutions in advancing research in this field. DISCUSSION: The increasing rate of publications on the prevention of EDs is encouraging. However, the actual number of studies on the prevention of EDs are limited, and the majority of this work is performed by a few research groups. Given the high concentration of publications within a few countries and research groups, increased funding, facilitation of prevention research on a wider scale, and engagement of more researchers and further collaboration are called for.

Effects of relative humidity on dry-aged beef quality.

This study was conducted to evaluate the effects of relative humidity (RH) on moisture loss and flavor in dry-aged beef. Sixteen strip loins were assigned to one of the four aging treatments: vacuum (WET), dry-aging at 50% RH, dry-aging at 70% RH, or dry-aging at 85% RH and aged for 42 days at 2 °C. Loins were evaluated for evaporation loss, trim loss, tenderness, sensory, and microbiological characteristics. Results show that lower RH results in accelerated moisture loss during the first 3 days of the aging process without significantly affecting the total amount of moisture loss. Pseudomonadales dominated the aerobically dry-aged loins while Enterobacteriales was the most abundant in the wet-aged samples. Dry-aged samples had increased content of free amino acids in the cooked meat juice compared to the wet-aged counterpart. Dry aging at 50% RH tended to associate with more desirable flavor notes.

Divergent Reactivity of Hemoglobin Isoforms α2Aß2 and α2Dß2 from Meleagris gallopavo in Native and Fatty Acid-Modified States.

Meleagris gallopavo (turkey) coexpresses distinct hemoglobin (Hb) isoforms, Hb α2Aß2 (HbA) and α2Dß2 (HbD), at a ratio of ∼3:1 (HbA:HbD). Herein, the reactivities of HbA and HbD were investigated in their native and free fatty acid (FFA)-modified states. Results indicated that HbD displays elevated autoxidation (kox) and an increased propensity to oxidize lipids in its reduced (oxy) and oxidized (met) forms. Interestingly, metHbD displayed less heme-globin cross-linking compared to HbA. Regarding FFA-modified Hb, we found that an FFA mixture and linoleic acid (LA) produced a bis-histidyl ferric (Bis-His) Hb species, decreasing the ability of Hb to oxidize lipids. Using molecular docking, we found LA to hydrogen bond with ß Arg C6, found at the α1ß2 interface, but the extent of Bis-His formation differs between HbA and HbD. Our findings suggest HbA displays elevated oxidative stability compared to HbD and that FFA may act as allosteric effectors of metHb.

Aerotolerance and Multi-Locus Sequence Typing of Campylobacter jejuni Isolated from Commercial Broiler Processing Plants.

Campylobacter jejuni is one of the leading causes of acute diarrhea in the United States. Despite being a microaerophilic pathogen, C. jejuni continues to endure within the domain of food production, especially in poultry processing. Recent research on aerotolerance indicates that close monitoring of this pathogen is necessary. A total of 40 C. jejuni isolates previously obtained from commercial broiler processing plants were analyzed for aerotolerance and genetic diversity. In addition, the effect of aerotolerance and storage time (days) on the survival of C. jejuni on broiler drumsticks at refrigeration (4 °C) and freezing conditions (-20 °C) was also evaluated. Out of 40 isolates, 25 (62.5%) were aero-sensitive (AS), 10 (25%) were intermediately aerotolerant (IAT), and 5 (12.5%) were hyper aerotolerant (HAT). The isolates belonged to four clonal complexes (CCs) and six sequence types, with the majority of isolates assigned to the CC-353 clonal complex. C. jejuni counts were reduced by 0.40 log CFU/g after 7 days at 4 °C and by 1.50 log CFU/g after 14 days at -20 °C, respectively, irrespective of aerotolerance (p < 0.001). At both refrigeration (p < 0.013) and freezing (p < 0.001), HAT showed greater reductions as compared to AS and IAT. These findings suggest that both refrigeration and freezing reduce C. jejuni counts.

Inosine 5'- monophosphate derived umami taste intensity of beef determination by electrochemistry and chromatography.

The umami sensation contributes to beef taste and acceptability. Inosine 5'- monophosphate (IMP), the most abundant 5'-ribonucleotide in meat, is known to impart an umami taste without the undesired side effects commonly associated with glutamate. Nevertheless, the investigation of IMP's role in beef flavor has thus far been overlooked. Traditional methods for detecting IMP have relied on liquid chromatography coupled with ultraviolet spectroscopy or mass spectrometry techniques. However, these methods are not practical for production settings due to the complexity and resource demands of sophisticated laboratory techniques. Alternative methods like cyclic voltammetry might offer more practical solutions for rapidly detecting IMP. The objectives of this study were to evaluate the efficiency of using electrochemistry and chromatography on differentiating beef strips spiked with different IMP contents. The IMP threshold was 0.30 mM determined by a trained panel using the Best Estimates Threshold method. Beef strip steaks of USDA Prime, Choice, and Select were spiked at 0.30 and 0.60 mM of IMP, based on green weight and an estimated moisture content of 65%. In this study, differences in the IMP content of steaks were not detected by liquid chromatography-mass spectrometry. However, the cyclic voltammetry approach differentiated IMP concentrations at 0.50 mM or above in aqueous solutions and subsequentially meat extracts from the buffered blank solutions. In conclusion, cyclic voltammetry holds potential as a rapid and effective approach for detecting IMP in beef and other meat products, offering promising applications for future research.

Salmonella Biofilm Formation under Fluidic Shear Stress on Different Surface Materials.

This study characterized biofilm formation of various Salmonella strains on common processing plant surface materials (stainless steel, concrete, rubber, polyethylene) under static and fluidic shear stress conditions. Surface-coupons were immersed in well-plates containing 1 mL of Salmonella (6 log CFU/mL) and incubated aerobically for 48 h at 37 °C in static or shear stress conditions. Biofilm density was determined using crystal violet assay, and biofilm cells were enumerated by plating on tryptic soy agar plates. Biofilms were visualized using scanning electron microscopy. Data were analyzed by SAS 9.4 at a significance level of 0.05. A surface-incubation condition interaction was observed for biofilm density (p < 0.001). On stainless steel, the OD600 was higher under shear stress than static incubation; whereas, on polyethylene, the OD600 was higher under static condition. Enumeration revealed surface-incubation condition (p = 0.024) and surface-strain (p < 0.001) interactions. Among all surface-incubation condition combinations, the biofilm cells were highest on polyethylene under fluidic shear stress (6.4 log/coupon; p < 0.001). Biofilms of S. Kentucky on polyethylene had the highest number of cells (7.80 log/coupon) compared to all other strain-surface combinations (p < 0.001). Electron microscopy revealed morphological and extracellular matrix differences between surfaces. Results indicate that Salmonella biofilm formation is influenced by serotype, surface, and fluidic shear stress.

Using liquid smoke to control infestations of the ham mite, Tyrophagus putrescentiae, on dry-cured hams during aging.

Eight treatments of edible coatings and nets including liquid smoke (SP and 24P) and xanthan gum (XG) were used to evaluate their effectiveness at controlling mite growth on dry-cured hams. Mite growth was controlled (P < 0.05) in both coating and netting treatments of 1% SP + 1% XG. Increasing SP concentration from 1% to 2% in the SP only treatments without XG did not control mite growth (P > 0.05) in the coating but controlled mite growth (P < 0.05) when infused in the nets. Both coating and netting treatments with 2% 24P + 1% XG controlled mite growth (P < 0.05), and ham cubes with 1% and 2% 24P in infused nets had mite numbers of 4.6 and 9.4, respectively. SP did not impact the sensory attributes of the ham. Results indicate that liquid smoke can potentially be added in coatings or ham nets to control mites and used in an integrated pest management program for dry-cured hams.

Melatonin Supplementation Alters Maternal and Fetal Amino Acid Concentrations and Placental Nutrient Transporters in a Nutrient Restriction Bovine Model.

Melatonin rescues uterine blood flow and fetal body weight in a seasonal dependent manner within a nutrient restriction bovine model. We sought to identify the effects of nutrient restriction, melatonin, and sampling time on maternal and fetal amino acids, and placental nutrient transporters. Pregnant heifers received adequate or restricted nutrition, and 20 mg of melatonin or placebo from gestational days 160-240 over two seasons. On day 240 maternal and fetal blood, amnion, and placentomes were collected. Amino acid concentrations were determined by gas chromatography-mass spectrometry. Caruncle and cotyledon tissues were assessed for nutrient transporter density by qPCR. Data were analyzed using the MIXED procedure of SAS for fixed effects. In fall, melatonin rescued effects of nutrient restriction on System N, Anion, and total maternal amino acids. Furthermore, melatonin rescued effects of nutrient restriction on Systems A, N, Br, Bo, and essential amnion amino acids. In summer, melatonin rescued effects of nutrient restriction in Systems Br and Bo maternal amino acids. Furthermore, melatonin rescued effects of nutrient restriction on caruncle SLC38A10 and SLC38A2. Melatonin rescued effects of nutrient restriction in a seasonal dependent manner. These data align with previous studies suggesting melatonin is a more effective therapeutic in summer months.

Roles of Aerotolerance, Biofilm Formation, and Viable but Non-Culturable State in the Survival of Campylobacter jejuni in Poultry Processing Environments.

Campylobacter jejuni is one of the most common causes of foodborne human gastroenteritis in the developed world. This bacterium colonizes in the ceca of chickens, spreads throughout the poultry production chain, and contaminates poultry products. Despite numerous on farm intervention strategies and developments in post-harvest antimicrobial treatments, C. jejuni is frequently detected on broiler meat products. This indicates that C. jejuni is evolving over time to overcome the stresses/interventions that are present throughout poultry production and processing. The development of aerotolerance has been reported to be a major survival strategy used by C. jejuni in high oxygen environments. Recent studies have indicated that C. jejuni can enter a viable but non-culturable (VBNC) state or develop biofilm in response to environmental stressors such as refrigeration and freezing stress and aerobic stress. This review provides an overview of different stressors that C. jejuni are exposed to throughout the poultry production chain and the genotypic and phenotypic survival mechanisms, with special attention to aerotolerance, biofilm formation, and development of the VBNC state.

The Prevalence of Salmonella and Campylobacter on Broiler Meat at Different Stages of Commercial Poultry Processing.

In poultry processing, Salmonella and Campylobacter contaminations are major food safety concerns. Peracetic acid (PAA) is an antimicrobial commonly used in commercial poultry processing to reduce pathogen prevalence so as to meet the USDA-FSIS performance standards. The objective of this study was to determine the prevalence of Salmonella and Campylobacter on broiler meat in various steps of commercial poultry processing in plants that use PAA. Post-pick, pre-chill, post-chill, and drumstick chicken samples were collected from three processing plants and mechanically deboned meat (MDM) was collected from two of the three plants. Each plant was sampled thrice, and 10 samples were collected from each processing step during each visit. Among the 420 samples, 79 were contaminated with Salmonella and 155 were contaminated with Campylobacter. Salmonella and Campylobacter contamination on the post-pick samples averaged 32.2%. Significant reductions in Salmonella and Campylobacter were observed in pre-chill to post-chill samples, where the prevalence was reduced from 34% and 64.4% to nondetectable limits and 1.1%, respectively (p < 0.001). Salmonella and Campylobacter remained undetectable on the drumstick samples in all three processing plants. However, the prevalence of Salmonella and Campylobacter on MDM was similar to the post-pick prevalence, which suggests substantial cross-contamination from post-chill to MDM.

An Examination of SARS-CoV-2 Transmission Based on Classroom Distancing in Schools With Other Preventive Measures in Place-Missouri, January-March 2021.

OBJECTIVES: Classroom layout plays a central role in maintaining physical distancing as part of a multicomponent prevention strategy for safe in-person learning during the COVID-19 pandemic. We conducted a school investigation to assess layouts and physical distancing in classroom settings with and without in-school SARS-CoV-2 transmission. METHODS: We assessed, measured, and mapped 90 K-12 (kindergarten through grade 12) classrooms in 3 Missouri public school districts during January-March 2021, prior to widespread prevalence of the Delta variant; distances between students, teachers, and people with COVID-19 and their contacts were analyzed. We used whole-genome sequencing to further evaluate potential transmission events. RESULTS: The investigation evaluated the classrooms of 34 students and staff members who were potentially infectious with COVID-19 in a classroom. Of 42 close contacts (15 tested) who sat within 3 ft of possibly infectious people, 1 (2%) probable transmission event occurred (from a symptomatic student with a longer exposure period [5 days]); of 122 contacts (23 tested) who sat more than 3 ft away from possibly infectious people with shorter exposure periods, no transmission events occurred. CONCLUSIONS: Reduced student physical distancing is one component of mitigation strategies that can allow for increased classroom capacity and support in-person learning. In the pre-Delta variant period, limited physical distancing (<6 ft) among students in K-12 schools was not associated with increased SARS-CoV-2 transmission.

Spoilage Bacteria Counts on Broiler Meat at Different Stages of Commercial Poultry Processing Plants That Use Peracetic Acid.

In poultry processing, spoilage microbes are persistent microorganisms, which affect the quality of broiler meat. Peracetic acid (PAA) is the most common antimicrobial used by commercial processing plants, which can reduce the prevalence of these microbes. The goal of this study was to determine the concentrations of aerobic bacteria, coliforms, lactic acid bacteria, and Pseudomonas on broiler meat in processing plants that use peracetic acid in various concentrations as the primary antimicrobial. Samples were collected from three processing plants at five processing steps: post-pick (defeathering), pre-chill, post-chill, mechanically deboned meat (MDM), and drumsticks. Samples were rinsed in buffered peptone water for bacteria isolation. Over six log CFU/sample of aerobic plate counts (APC), lactic acid bacteria, and coliforms were detected on post-pick samples. All spoilage bacteria were reduced to nondetectable levels on post-chill samples (p < 0.001). However, the presence of all bacteria on mechanically deboned meat (MDM) samples indicated varying degrees of cross contamination from post-chill and MDM samples. These results suggest PAA effectively reduces spoilage microbes in chilling applications irrespective of differences in PAA concentrations. However, due to the levels of spoilage microbes detected in MDM, it may be worth investigating the potential interventions for this stage of processing.

In Utero Heat Stress Has Minimal Impacts on Processed Pork Products: A Comparative Study.

This study aimed to determine what effects in utero heat stress (IUHS) in pigs may have on quality of processed pork products. In two experiments, patties and emulsion sausages were prepared from lean and fat from pigs subjected to IUHS or in utero thermoneutral (IUTN) conditions. Patties formulated to contain 25% added fat had altered textural properties compared to those without additional fat, as shown by lower hardness, cohesiveness, springiness, and chewiness values (p < 0.05), which was not affected by IUHS treatment. Neither fat content nor IUHS treatment affected fluid losses of patties (p > 0.05). In general, 25% added fat patties had greater L*, a*, b*, hue angle, and chroma values than lean patties (p < 0.05). However, 25% added fat patties from the IUHS treatment maintained superior color stability during aerobic display, despite lean patties from this treatment exhibiting increased lipid oxidation (p < 0.05). For emulsion sausages, minimal differences in quality attributes and oxidative stability were found between treatment groups. Subcutaneous fat from IUHS pigs had greater C20:1 and C20:2 than IUTN (p < 0.05), although the magnitude of these differences was slight. Overall, the findings of this study suggest IUHS would have minimal impacts on the functional properties of raw pork, resulting in similar final quality of processed products to IUTN.

Establishment of an in-house real-time RT-PCR assay for the detection of severe acute respiratory syndrome coronavirus 2 using the first World Health Organization international standard in a resource-limited country.

BACKGROUND: The COVID-19 pandemic caused by SARS-CoV-2 remains public health burdens and many unresolved issues worldwide. Molecular assays based on real-time RT-PCR are critical for the detection of SARS-CoV-2 in clinical specimens from patients suspected of COVID-19. OBJECTIVE: We aimed to establish and validate an in-house real-time RT-PCR for the detection of SARS-CoV-2. METHODOLOGY: Primers and probes sets in our in-house real-time RT-PCR assay were designed in conserved regions of the N and E target genes. Optimized multiplex real-time RT-PCR assay was validated using the first WHO International Standard (NIBSC code: 20/146) and evaluated clinical performance. RESULTS: The limit of detection validated using the first WHO International Standard was 159 IU/ml for both E and N target genes. The evaluation of clinical performance on 170 clinical samples showed a positive percent agreement of 100% and the negative percent agreement of 99.08% for both target genes. The Kappa value of 0.99 was an excellent agreement, the strong correlation of Ct values observed between two tests with r2  = 0.84 for the E gene and 0.87 for the N gene. Notably, we assessed on 60 paired saliva and nasopharyngeal samples. The overall agreement was 91.66%, and Kappa value of 0.74 showed a high agreement between two types of samples. When using nasopharyngeal swabs as the reference standard, positive percent agreement, and negative percent agreement were 91.83% and 90.90%, respectively. CONCLUSION: In the present study, we established and validated an in-house real-time RT-PCR for molecular detection of SARS-CoV-2 in a resource-limited country.

Oxidative stress biomarkers and free amino acid concentrations in the blood plasma of moderately exercised horses indicate adaptive response to prolonged exercise training.

Oxidative stress caused by routine physical stressors may negatively impact the performance of equine athletes; thus, the present study identifies oxidative biomarkers in the blood plasma of exercising horses. Stock-type horses were subject to a standardized moderate-intensity exercise protocol 3 times per week for 8 wk. Exercise protocol followed NRC guidelines consisting of 30% walk, 55% trot, and 15% canter, with a target heart rate (HR) of 90 BPM. Blood plasma was collected in wk 1, 2, 7, and 8 immediately before and 0, 30, 60, and 90 min after exercise and analyzed for total antioxidant capacity (TAC), thiobarbituric acid reactive substance (TBARS), glutathione peroxidase activity (GPx), and superoxide dismutase activity (SOD). Data were analyzed as repeated measures with wk, d, time, and their interactions as fixed effects. The TAC on day 2 (0.40 mM Trolox) was 7.5% greater than on day 3 (P = 0.013). There were wk × d × time interactions for SOD, TBARS, and GPx (P < 0.001). The TBARS remained at pre-exercise baseline (d-1 wk-1; 2.7 µM malondialdehyde) for most collection times within weeks 1, 7, and 8 (P ≥ 0.058); however, TBARS increased by 0.24 to 0.41 µM on day 2 of week 2 post-exercise (P < 0.001) and remained similarly elevated on day 3 pre- and immediately post-exercise (P < 0.001). The GPx similarly remained at baseline (172.6 µM/min; P ≥ 0.621) but increased by 48.18 to 83.4 µM/min at most collection times on days 1 and 2 of week 2 (P ≤ 0.023). The SOD remained at baseline (167.2 U/ mL; P ≥ 0.055) until increasing by 11.28 to 15.61 U/mL at 30 min post-exercise on day 1, week 1 and at most collection times on day 3, week 8 (P ≤ 0.043). Amino acids with antioxidant properties such as Met, Tyr, and Trp drastically decreased from weeks 2 to 8 (P < 0.001). Met and Tyr also decreased from -60 to 90 min (P < 0.047), whereas there was no time effect on Trp concentration (P = 0.841). The current study indicates the time-dependent nature of oxidative stress concerning persistent stressors such as exercise.

Performance horses are subjected to numerous stressors. These stressors may subsequently impact their overall performance. The present study measured oxidative stress biomarkers in the blood of exercising horses. Horses were moderately exercised over an 8-wk period and blood plasma was collected to measure total antioxidant capacity (TAC), thiobarbituric acid reactive substance (TBARS), glutathione peroxidase activity (GPx), and superoxide dismutase activity (SOD). Amino acid concentration was also evaluated. The TAC was greater on day 2 vs. day 3. The TBARS remained at pre-exercise (baseline) at most times except for increasing on day 2 of week 2 post-exercise. The GPx also remained at baseline for most times but increased on days 1 and 2 of week 2. The SOD remained at baseline until increasing at 30 min post-exercise on day 1, week 1 and at most collection times on day 3, week 8. Amino acids with antioxidant properties drastically decreased from weeks 2 to 8. Horses are exposed to a variety of physical stressors on a regular basis that may produce similar effects in the equine stress response. Understanding the response in the equine athlete when exposed to new stressors is crucial in determining how to prevent oxidative damage in future athletes.

Evaluation of Test to Stay Strategy on Secondary and Tertiary Transmission of SARS-CoV-2 in K-12 Schools - Lake County, Illinois, August 9-October 29, 2021.

The COVID-19 pandemic has resulted in school closures and reduction of in-person learning (1). In August 2021, the Lake County Health Department (LCHD) in Illinois introduced a Test to Stay (TTS) strategy, whereby unvaccinated students, teachers, and staff members with certain school-related COVID-19 exposures could remain in school and participate in school-related extracurricular activities. Eligibility to participate in TTS required the following conditions to be met: 1) the exposure occurred while both the person with COVID-19 (index patient) and the close contact were masked; 2) the close contact remained asymptomatic, practiced consistent mask wearing, and maintained physical distancing; and 3) the close contact underwent testing for SARS-CoV-2 (the virus that causes COVID-19) on days 1, 3, 5, and 7 after exposure to the index patient. LCHD permitted kindergarten through grade 12 (K-12) schools in Lake County to implement TTS; 90 schools, representing 31 school districts in Lake County, implemented TTS during August 9-October 29, 2021. During the implementation period, 258 COVID-19 cases were reported. Among 1,035 students and staff members enrolled in TTS, the secondary attack risk (number of close contacts who received a positive SARS-CoV-2 test result within 14 days after exposure to an index patient, divided by total number of close contacts) was 1.5% (16 of 1,035). Among the 16 secondary cases identified, all were in students, and none appeared to transmit SARS-CoV-2 to other school-based contacts. However, nine tertiary cases were identified among household contacts of the 16 secondary cases, and four of the nine were fully vaccinated. Assuming a maximum of 8 missed school days for every 10-day quarantine period, up to 8,152 in-person learning days were saved among TTS participants. Implementation of TTS with other concurrent prevention strategies, including masking and physical distancing, limited further spread of SARS-CoV-2 within K-12 schools and allowed students to safely sustain in-person learning. Although vaccination remains the leading public health recommendation to protect against COVID-19 for those aged ≥5 years, schools might consider TTS as an option for allowing close contacts who are not fully vaccinated to remain in the classroom as an alternative to home quarantine.