Sterilization of Human Amniotic Membrane Using an Ozone Hydrodynamic System.

Human amniotic membrane (hAM) is an important biomaterial for Tissue Engineering, due to its great regenerative properties and potential use as a scaffold. The most used procedure to sterilize biomaterials is gamma-irradiation, but this method can affect several properties, causing damage to the structure and reducing the growth factors. The present work evaluated the efficiency of a new method based on ozonated dynamic water for hAM sterilization. HAM fragments were experimentally contaminated with Staphylococcus aureus, Escherichia coli, Candida albicans, Staphylococcus epidermidis, and Clostridium sporogenes (106 CFU/mL) and submitted to sterilization process for 5, 10 and 15 min. The analyses did not reveal microbial activity after 10 min for S. aureus and C. sporogenes and after 15 min for E. coli and S. epidermidis. The microbial activity of C. albicans was reduced with the exposure time increase, but the evaluated time was insufficient for complete sterilization. The depyrogenation process was investigated for different ozonation times (15, 20, 25, 30, and 35 min) to evaluate the ozone sterilization potential and presented promising results after 35 min. The ozone effect on hAM structure was evaluated by histological analysis. A decrease in epithelium average thickness was observed with the exposure time increase. Furthermore, some damage in the epithelium was observed when hAM was exposed for 10 and 15 min. It can indicate that ozone, besides being effective in sterilization, could promote the hAM sample's de-epithelization, becoming a possible new method for removing the epithelial layer to use hAM as a scaffold.

Tourniquets, types and techniques in emergency prehospital care: A narrative review.

Massive uncontrolled hemorrhage is an important cause of preventable death in trauma. Therefore, applying an arterial tourniquet (TQ) is recommended as a pre-hospital measure to control bleeding after severe traumatic bleeding. Limb TQ applies circumferential compression proximally to the injury site to compress the arteries, resulting in blood flow and consequently hemorrhage interruption. The use of commercial tourniquets (C-TQ), which are designed, tested, and registered to control hemorrhages in pre-hospital care, is a consensus. However, they are still uncommon in many prehospital emergency services and the overall level of evidence in most studies is low. This narrative review aimed to characterize the importance of tourniquets use in prehospital emergency care and its application techniques. Furthermore, it proposes to stimulate the development of new devices, more accessible and easier to use, to suggest new directions of studies and medical education demands, with manikin and simulation development.

Cardiopulmonary and hematological effects of infrared LED photobiomodulation in the treatment of SARS-COV2.

BACKGROUND: COVID-19 disease is caused by SARS-CoV-2 which can trigger acute respiratory syndrome, which presents with dense alveolar and interstitial infiltrates and pulmonary edema, causing severe hypoxemia and significant alteration to pulmonary mechanics with reduced pulmonary compliance. The photobiomodulation technique alters cellular and molecular metabolism, showing promising results regarding the reduction of acute pulmonary inflammation. OBJECTIVE: To compare the photomodulation technique using near-infrared LED to conventional respiratory physiotherapy treatment in patients with COVID-19 in reversing acute conditions, reducing hospitalization time, and decreasing the need for oxygen therapy. METHODOLOGY: The cohort was comprised of 30 patients undergoing COVID-19 treatment who were divided and allocated into two equal groups randomly: the LED group (LED), treated with infrared LED at 940 nm and conventional therapy, and the control group (CON), who received conventional treatment (antibiotic therapy for preventing superimposed bacterial infections, and physiotherapy) with LED irradiation off. Phototherapy used a vest with an array of 300 LEDs (940 nm) mounted on a 36 cm × 58 cm area and positioned in the patient's anterior thoracic and abdominal regions. The total power was 6 W, with 15 min irradiation time. Cardiopulmonary functions and blood count were monitored before and after treatment. The patients were treated daily for 7 days. Statistical analysis was conducted using a two-tailed unpaired Student's t-test at a significance level of α = 0.05. RESULTS: Post-treatment, the LED group showed a reduction in hospital discharge time and a statistically significant improvement for the following cardiopulmonary functions: Partial Oxygen Saturation, Tidal Volume, Maximum Inspiratory, and Expiratory Pressures, Respiratory Frequency, Heart Rate, and Systolic Blood Pressure (p < 0.05). Regarding blood count, it was observed that post-treatment, the LED group presented with significant differences in the count of leukocytes, neutrophils, and lymphocytes. CONCLUSION: Photobiomodulation therapy can be used as a complement to conventional treatment of COVID-19, promoting the improvement of cardiopulmonary functions, and minimization of respiratory symptoms.

Effectiveness of intravesical ozone in interstitial cystitis by the O'Leary-Sant symptom index.

INTRODUCTION AND HYPOTHESIS: A prospective clinical, preliminary study was performed in patients with interstitial cystitis/bladder pain syndrome (IC/BPS) who were nonresponders to conventional treatment and received intravesical ozone as a therapeutic alternative. METHODS: Sixteen patients received six applications of intravesical ozone at a concentration of 41 µg/mL. We evaluated therapeutic efficacy by the percentage reduction of Interstitial Cystitis Symptom and Problem Index scores (ICSI/ICPI-the O'Leary-Sant symptom index), recurrence rate, nonresponse, and side effects in scores collected on admission (pre-treatment), at the end of the therapeutic protocol (post-treatment), and 180 days (follow-up) after the last ozone application. RESULTS: The mean age of women was 52.9 years (SD: 15.5), and the duration of symptoms was 5.7 years (SD: 7.1). The median ICSI on admission was 17 (IQR: 14.25-19.5) and at follow-up was 0.5 (IQR: 0-2), with a reduction of 97.5% (CI: 85.7-100). The median ICSI/ICPI on admission was 31.5 (IQR: 29-35.2) and at follow-up was 2.0 (IQR: 0-3.75), with a reduction of 92.3% (CI: 88.8-100). The recurrence rate was only 6.25%, and no patients were nonresponders to the treatment. CONCLUSIONS: The application of intravesical ozone was effective in the treatment of patients with IC/BPS who were nonresponders to conventional therapy, showing a progressive and safe effect, at least in the short term.

Analysis of pain relief and functional recovery in patients with rotator cuff tendinopathy through therapeutic ultrasound and photobiomodulation therapy: a comparative study.

This study aimed to compare shoulder tendinopathy treatment with therapeutic ultrasound combined with LED photobiomodulation therapy using LED-infrared (850 nm) or LED-red (640 nm). The study assessed 75 patients, aged 45 to 70 years, distributed into five experimental groups (15 patients each): therapeutic ultrasound (US), infrared light irradiation (IR), visible red light irradiation (VR), infrared light and ultrasound combined (IR-US), and red light in conjunction with ultrasound (VR-US). The ultrasound parameters are 1 MHz, 0.5 W/cm2 (SATA), and 100 Hz repetition rate, applied for 4 min each session. LED irradiation protocols were as follows: 3 points, 7.5 J per point, IR-LED 750 mW, 10 s, VR-LED 250 mW, 30 s. LED irradiation is followed by ultrasound in the combined therapies. The efficiency of the five therapies was evaluated assessing 12 parameters: quality of life (Health Assessment Questionnaire, HAQ), pain intensity (Visual Analog Scale, VAS), articular amplitude of shoulder movement (flexion, extension, abduction, adduction, medial rotation, lateral rotation), muscle strength (abduction, lateral rotation), and electromyography (lateral rotation, abduction). Treatments comprised 12 sessions for 4 weeks. Intra-group analysis showed that the five therapies significantly improved the recovery of all parameters after treatment. Regarding the comparison of irradiated therapies and ultrasound, statistical analysis showed that IR-US was a better treatment than US for all 12 parameters. IR treatment exceeded US on 9 items, whereas that VR and VR-US therapies exceeded US in 7 and 10 parameters, respectively (p < 0.05). Because of that, IR-US shows to be the best treatment for rotator cuff tendinopathy. In conclusion, improvements in quality of life, pain intensity relief, shoulder amplitude motion, and muscle strength force obtained with ultrasound therapy are enhanced by adding infrared LED irradiation to ultrasound for patients suffering from rotator cuff tendinopathy. This study was registered with the Brazilian Registry of Clinical Trials (ReBEC) under Universal Trial Number (UTN) U1111-1219-3594 (2018/22/08).

Systemic Effects of Photobiomodulation on Blood Components in the Treatment of Community-Acquired Pneumonia.

Background: The analysis of the complete blood count (CBC) of patients with community-acquired pneumonia (CAP) is an essential practice both for diagnosing the disease and for evaluating the patient's clinical evolution. It is proposed in the present study to analyze the hematological alterations resulting from photobiostimulation using near-infrared light-emitting diodes (LEDs) in patients with CAP. Methods: This was a clinical, prospective, blinded, and descriptive longitudinal study that involved 21 patients undergoing CAP treatment who were divided into two groups: LED, 11 patients who were treated with infrared LED and conventional treatment; and CON (control), 10 patients who received only conventional treatment (antibiotic therapy and physiotherapy). Physiotherapy was applied before LED irradiation in the LED group. The patients' CBCs were obtained before and after treatment, and erythrocyte counts, hemoglobin and hematocrit concentrations, and leukocyte and platelet counts were assessed. The phototherapy was performed with a vest with an array of 300 LEDs (940 nm) mounted on an area of 36 × 58 cm and positioned in the patient's anterior thoracic and abdominal regions. The total power was 6 W, with 15 min of irradiation time. The patients were treated daily for seven consecutive days. Statistical analyses of the intra- and intergroups of CBC data were done using Student's t-test and one-way ANOVA (analysis of variance), respectively, both at the significance level of α = 0.05. Results: There was a statistically significant recovery difference after treatment in the LED group compared with the CON group for erythrocytes, hemoglobin, leukocytes, segmented and band neutrophils, lymphocytes, and monocytes (p < 0.05). The greatest differences between the LED and CON groups were lymphocyte count reduction (60% vs. 16%), erythrocyte increase (86% vs. 35%), and leukocyte reduction (28% vs. 15%). Conclusions: The hematologic components of CAP patients recovered their normal values faster with conventional treatment associated with infrared LED therapy, thus indicating greater treatment efficiency when compared with the conventional therapy. This study was registered with the Brazilian Registry of Clinical Trials (ReBeC) under Universal Trial Number (UTN) U1111-1229-1296 (2019/06/05).

Efficiency of nitrogen and potassium application on phytotechnical parameters and yield of melon / Eficiência da aplicação de nitrogênio e potássio sobre caracteres fitotécnicos e rendimento do meloeiro

Phytotechnical parameters, yield and fertilizer use efficiency are relevant to the rational management of fertigation, especially in cultivation of high technological level. Thus, the objective was to evaluate the influence and efficiency of nitrogen (N) and potassium (K) application on the phytotechnical parameters, yield and nutritional efficiency of yellow melon in a fertigation system. The experiment was conducted in the city of Bom Jesus-PI, Brazil, from January to April 2016, in a strip-block design with four replicates, and the treatments consisted of five N levels (0, 45, 90, 135 and 180 kg ha-1 in the form of urea) and five K levels (0, 60, 120, 180 and 240 kg ha-1 in the form of potassium chloride), applied through fertigation. Collar diameter, main branch length, leaf chlorophyll content, number of leaves, leaf area index, biomass accumulation, fruit yield, and N and K use efficiencies were evaluated. Applications of 180 kg ha-1 of N and 240 kg ha-1 of K, respectively, led to the highest growth of the melon, while maximum production was obtained with the use of 112.50 and 165 kg ha-1 of N and K, respectively. The efficiency of N and K use decreased with increasing levels.

As características fitotécnicas, de rendimento e de eficiência de uso dos fertilizantes são relevantes para o manejo racional da fertirrigação, especialmente em cultivo de elevado nível tecnológico. Níveis crescentes de N e K promoverão maior crescimento e produtividade do meloeiro. Neste sentido, objetivou-se avaliar a influência e a eficiência da aplicação de nitrogênio e potássio sobre as características fitotécnicas, de rendimento e de eficiência do meloeiro amarelo em sistema de fertirrigação. O experimento foi conduzido na cidade de Bom Jesus ­ PI, Brasil durante o período de janeiro a abril de 2016. O delineamento experimental adotado foi de blocos em faixas com quatro repetições, e os tratamentos constituídos por cinco níveis de nitrogênio (0, 45, 90, 135 e 180 kg ha-1 na forma de ureia) e cinco níveis de potássio (0, 60, 120, 180 e 240 kg ha-1na forma de cloreto de potássio) aplicados via fertirrigação. Avaliou-se os caracteres fitotécnicos, rendimento de frutos e as eficiências de uso do nitrogênio e do potássio. As aplicações de 180 kg ha-1 de N e 240 kg ha-1 de K promoveram maior crescimento do meloeiro, enquanto que a máxima produção foi obtida com o uso de 112,50 e 165 kg ha-1 de nitrogênio e potássio, respectivamente. As eficiências de uso do nitrogênio e do potássio diminuíram com o aumento dos níveis aplicadas.

Impact of lockdown on bed occupancy rate in a referral hospital during the COVID-19 pandemic in northeast Brazil

Abstract Coronaviruses are known to be responsible for infections in humans since the 1960s and have accounted for epidemics in recent human history. More recently, in 2019, a disease caused by a new coronavirus appeared in China, in the province of Wuhan, with a characteristic of greater infectivity, called COVID-19, which has caused a new world pandemic. Considering the need to contain the advance in the number of cases, based on the high rate of transmissibility, several countries have adopted extreme social distancing measures, including the so-called 'lockdown'. Despite the socioeconomic side effects, the aforementioned measure reduced the progression of the pandemic in countries that adopted it. In Brazil, the state of Ceará was one of the first epicenters of the disease in the country and the state capital city of Fortaleza, on May 8, implemented the lockdown measure to contain the increase in the number of cases. It was then observed, in a tertiary hospital, which is a referral for COVID-19 cases, a decrease in the daily occupancy rate of beds reserved for the pandemic after the lockdown onset, evidencing that this measure leads to a sustainable reduction in bed occupation rates, thus preventing the collapse and overload in health services.

Impact of lockdown on bed occupancy rate in a referral hospital during the COVID-19 pandemic in northeast Brazil.

Coronaviruses are known to be responsible for infections in humans since the 1960s and have accounted for epidemics in recent human history. More recently, in 2019, a disease caused by a new coronavirus appeared in China, in the province of Wuhan, with a characteristic of greater infectivity, called COVID-19, which has caused a new world pandemic. Considering the need to contain the advance in the number of cases, based on the high rate of transmissibility, several countries have adopted extreme social distancing measures, including the so-called 'lockdown'. Despite the socioeconomic side effects, the aforementioned measure reduced the progression of the pandemic in countries that adopted it. In Brazil, the state of Ceará was one of the first epicenters of the disease in the country and the state capital city of Fortaleza, on May 8, implemented the lockdown measure to contain the increase in the number of cases. It was then observed, in a tertiary hospital, which is a referral for COVID-19 cases, a decrease in the daily occupancy rate of beds reserved for the pandemic after the lockdown onset, evidencing that this measure leads to a sustainable reduction in bed occupation rates, thus preventing the collapse and overload in health services.

Photobiomodulation: Shining Light on COVID-19.

Objective: To evaluate the hypothesis that light could reduce the lethality of COVID-19. Methods: Most models for projections of the spread and lethality of COVID-19 take into account the ambient temperature, neglecting light. Recent advances in understanding the mechanism of action of COVID-19 have shown that it causes a systemic infection that significantly affects the hematopoietic system and hemostasis, factors extremely dependent of light, mainly in the region of visible and infrared radiation. Results: In the COVID-19 patients hemoglobin is decreasing and protoporphyrin is increasing, generating an extremely harmful accumulation of iron ions in the bloodstream, which are able to induce an intense inflammatory process in the body with a consequent increase in C-reactive protein and albumin. Observing the unsaturation characteristics of the cyclic porphyrin ring allows it to absorb and emit radiation mainly in the visible region. This characteristic can represent an important differential to change this process in the event of an imbalance in this system, through the photobiomodulation to increase the production of adenosine triphosphate (ATP) using red and near-infrared radiation (R-NIR) and vitamin D using ultraviolet B (UVB) radiation. These two compounds have the primary role of activating the defense mechanisms of the immune system, enabling greater resistance of the individual against the attack by the virus. According to the theory of electron excitation in photosensitive molecules, similar to hemoglobin heme, after the photon absorption there would be an increase in the stability of the iron ion bond with the center of the pyrrole ring, preventing the losses of heme function oxygen transport (HbO2). The light is also absorbed by cytochrome c oxidase in the R-NIR region, with a consequent increase in electron transport, regulating enzyme activity and resulting in a significant increase of oxygen rate consumption by mitochondria, increasing ATP production. Conclusions: The most favorable range of optical radiation to operate in this system is between R-NIR region, in which cytochrome c oxidase and porphyrin present absorption peaks centered at 640 nm and HbO2 with absorption peak centered at 900 nm. Based on the mechanisms described earlier, our hypothesis is that light could reduce the lethality of COVID-19.

Comparative analysis of the effects of ozone and ultrasound on Streptococcus mutans

Streptococcus mutans is one of the principal pathogens of the human oral habitat, being one of the principal etiological agents of carious lesions. Ozone is a powerful oxidant, it has the ability to inactivate microorganisms in general, and ultrasound is an acoustic system generated through a piezoelectric crystal that also presents microbicidal effects. In the present study, a comparative analysis was made of the damage caused to Streptococcus mutans in vitro by ultrasound and ozone, through scanning electron microscopy (SEM) and atomic force microscopy (AF) analysis. In addition, flow cytometry was used to determine microbial viability and the formation of Reactive Oxygen Species (ROS) after the application of different techniques. The data obtained by means of micro- scopic analysis reveal that both ozone and ultrasound produce morphological alterations in bacteria, which become rod-shaped organisms. In addition to this deformation, on the microbial surface it was possible to identify crater-like impressions. In contrast, the irregularity of protuber- ances on the surface of the microbial wall was only detected when ozone was employed. Regarding the formation of ROS, it was observed that that ozone induces a significant growth (p < .05) of these molecules, while ultrasound does not present this effect. Ozone and ultrasound present micro- bicidal effects, however, ozone is more efficient.

Development and Validation of a Mobile Application for the Teaching of Electrocardiogram / Desenvolvimento e Validação de um Aplicativo Móvel para o Ensino de Eletrocardiograma

ABSTRACT Introduction The interpretation of the electrocardiogram (ECG) is fundamental for the identification of cardiovascular diseases, which are among the main causes of death in the world. The acquisition of this competence is essential in the training of the general practitioner and the use of new teaching tools, based on technology such as the use of mobile learning, can facilitate the acquisition of this knowledge. Objectives The objective of this study was to develop and evaluate the usability and the potentiality for the use in medical education of a mobile teaching application for ECG interpretation. Methods With the participation of two health professors and a computer scientist, a systems analyst, a programmer and a graphic designer, a mobile application was developed to teach ECG interpretation using the Java language. For validation analysis, a usability evaluation questionnaire based on the System Usability Scale (SUS) and a questionnaire used to evaluate the suitability of software for use in medical education, previously translated into Portuguese and applied in Brazil, were used. Results The "ECG Fácil" application was developed for off-line use and free access on iOS and Android platforms. In the validation phase of the application, a total of 109 students had free access to the mobile application for 6 weeks and then evaluated usability through a SUS-based questionnaire. The answers to the questionnaire showed good reliability, according to the validation analysis by Cronbach's alpha coefficient (value: 0.74), and the application presented an excellent acceptance with a mean score on the SUS scale of 85.3. Meanwhile, fifteen faculty members evaluated the application through the questionnaire used to assess the suitability of software for use in medical education, with most agreeing with items indicating that it is suitable for use in medical education. Conclusion The "ECG Fácil" application was considered to be of good usability by students and suitable for educational purpose by teachers. Future studies with this application will be needed to assess the acquisition and retention of knowledge about ECG interpretation by students.

RESUMO Introdução A interpretação do eletrocardiograma (ECG) é fundamental para a identificação de doenças cardiovasculares, que estão entre as principais causas de morte no mundo. A aquisição dessa competência é essencial na formação do médico generalista, e o uso de novas ferramentas de ensino, apoiadas na tecnologia, como o mobile learning, pode facilitar a aquisição desse conhecimento. Objetivos Este estudo teve por objetivo desenvolver e avaliar a usabilidade e a potencialidade para o uso em educação médica de um aplicativo móvel de ensino para interpretação do ECG. Métodos Com a participação de dois professores da área da saúde e um da computação, um analista de sistemas, um programador e um designer gráfico, foi desenvolvido um aplicativo móvel para ensino da interpretação do ECG, utilizando-se a linguagem Java. Para análise de validação foram empregados um questionário de avaliação da usabilidade baseado no System Usability Scale (SUS) e um questionário utilizado para avaliar a adequação de softwares para uso em educação médica, previamente traduzido para o português e aplicado no Brasil. Resultados Foi desenvolvido o aplicativo "ECG Fácil" para uso off-line e de acesso gratuito nas plataformas iOS e Android. Na fase de validação do aplicativo, 109 discentes tiveram acesso livre ao aplicativo móvel durante seis semanas e depois avaliaram a usabilidade por meio de questionário baseado no SUS. As respostas ao questionário mostraram boa confiabilidade, conforme a análise de validação pelo coeficiente alfa de Cronbach (valor: 0,74), e o aplicativo apresentou excelente aceitação, com escore médio de 85,3 na escala SUS. Enquanto isso, 15 docentes avaliaram o aplicativo por meio do questionário utilizado para avaliar a adequação de softwares para uso em educação médica, tendo a maioria concordado com os itens que indicam que ele é adequado ao uso em educação médica. Conclusão O aplicativo "ECG Fácil" foi considerado de boa usabilidade pelos alunos e adequado à finalidade educacional pelos professores. Estudos futuros com esse aplicativo serão necessários para avaliar a aquisição e a retenção de conhecimento sobre a interpretação do ECG pelos alunos.

Analysis of damage on the Streptococcus mutans immersed in ozonated water: preliminary study for application as mouth rinse

Ozonated water has been demonstrated to induce significant results in terms of the elimination ofmicroorganisms. The present study assessed the damage toStreptococcusmutansafter exposureto ozonated water; the ozone generator was adjusted to provide an outlet concentration of60 mg/L, the samples were submitted to different ozonation times 1, 2, 4, 6, and 10 mi. Scanningelectron microscopy and atomic force images were obtained to identify damage to the bacteria,followed by reactive oxygen species (ROS) evaluation and microbial viability. The results showed asignificant reduction in viability and the images evidenced the generation of gaps on themicrobial wall and surface layer alterations. Ozone can induce significant damage toS.mutans,thus suggesting that the use of ozonated water to prevent carious lesion formation is extremelypromising.

Analysis of damage on the Streptococcus mutans immersed in ozonated water: preliminary study for application as mouth rinse

Ozonated water has been demonstrated to induce significant results in terms of the elimination ofmicroorganisms. The present study assessed the damage toStreptococcusmutansafter exposureto ozonated water; the ozone generator was adjusted to provide an outlet concentration of60 mg/L, the samples were submitted to different ozonation times 1, 2, 4, 6, and 10 mi. Scanningelectron microscopy and atomic force images were obtained to identify damage to the bacteria,followed by reactive oxygen species (ROS) evaluation and microbial viability. The results showed asignificant reduction in viability and the images evidenced the generation of gaps on themicrobial wall and surface layer alterations. Ozone can induce significant damage toS.mutans,thus suggesting that the use of ozonated water to prevent carious lesion formation is extremelypromising.

LED phototherapy in full-thickness burns induced by CO2 laser in rats skin.

Many studies have been conducted on the treatment of burns because they are important in morbidity and mortality. These studies are mainly focused on improving care and quality of life of patients. The aim of this study was evaluate the LED phototherapy effects in rats skin full-thickness burns induced by CO2 laser. The animals were divided in NT group that did not received any treatment and LED group that received LED irradiation at 685 nm, 220 mW, and 4.5 J/cm2 during 40 s by burned area. Biopsies were obtained after 7, 14, and 21 days of treatment and submitted to histological and immunohistochemical analysis. The LED phototherapy shows anti-inflammatory effects, improves angiogenesis, and stimulates the migration and proliferation of fibroblasts. The T CD8+ lymphocytes were more common in burned areas compared to T CD4+ lymphocytes since statistically significant differences were observed in the LED group compared to the NT group after 7 days of treatment. These results showed that LED phototherapy performs positive influence in full-thickness burns repair from the healing process modulated by cellular immune response. The obtained results allowed inferring that burns exhibit a characteristic cell immune response and this cannot be extrapolated to other wounds such as incision and wounds induced by punch, among others.

Use of photodynamic therapy in the treatment of bovine subclinical mastitis.

BACKGROUND: Bovine mastitis is a disease that causes a severe drawback in dairy production. Conventional treatments with antibiotic could leave antibiotic residues in the milk. The aim of this study was to evaluate the effect of photodynamic therapy in the treatment of bovine subclinical mastitis to develop an in vivo therapeutic protocol that could be used in routine farm practice, favoring the early return to production. METHODS: Forty cows with subclinical mastitis (n = 40) were divided into 4 groups (control, photodynamic therapy - PDT, light irradiation - LED, and photosensitizer - PS). Control group received no treatment, PDT group received application of 1.0 mL of 2.5% toluidine blue photosensitizer followed by LED irradiation at λ = 635 nm, the LED group was treated with LED irradiation alone, and the PS group received only 2.5% toluidine blue dye. LED irradiation was applied to the mammary gland by means of an acrylic light guide coupled to the LED equipment. The PDT and LED groups were irradiated with 200 J/cm2 at three different positions inside the mammary gland. Milk samples were collected at 0 h, 12 h, 24 h after treatment for microbial identification and total bacterial count. RESULTS: The treatment of the PDT group showed significant difference p < 0.05, characterizing the efficiency of this technique with the reduction of the microorganisms Streptococcus dysgalactiae and coagulase-negative Staphylococcus. CONCLUSION: Photodynamic therapy was effective when applied in vivo for subclinical bovine mastitis. There was no need to separate the animal from production.