Light-activated conjugated polymer nanoparticles to defeat pathogens associated with bovine mastitis.

Bovine mastitis (BM) represents a significant challenge in the dairy industry. Limitations of conventional treatments have prompted the exploration of alternative approaches, such as photodynamic inactivation (PDI). In this study, we developed a PDI protocol to eliminate BM-associated pathogens using porphyrin-doped conjugated polymer nanoparticles (CPN). The PDI-CPN protocol was evaluated in four mastitis isolates of Staphylococcus and in a hyper-biofilm-forming reference strain. The results in planktonic cultures demonstrated that PDI-CPN exhibited a bactericidal profile upon relatively low light doses (∼9.6 J/cm2). Furthermore, following a seven-hour incubation period, no evidence of cellular reactivation was observed, indicating a highly efficient post-photodynamic inactivation effect. The successful elimination of bacterial suspensions encouraged us to test the PDI-CPN protocol on mature biofilms. Treatment using moderate light dose (∼64.8 J/cm2) reduced biofilm biomass and metabolic activity by up to 74% and 88%, respectively. The impact of PDI-CPN therapy on biofilms was investigated using scanning electron microscopy (SEM), which revealed nearly complete removal of the extracellular matrix and cocci. Moreover, ex vivo studies conducted on bovine udder skin demonstrated the efficacy of the therapy in eliminating bacteria from these scaffolds and its potential as a prophylactic method. Notably, the histological analysis of skin revealed no signs of cellular degeneration, suggesting that the protocol is safe and effective for BM treatment. Overall, this study demonstrates the potential of PDI-CPN in treating and preventing BM pathogens. It also provides insights into the effects of PDI-CPN on bacterial growth, metabolism, and survival over extended periods, aiding the development of effective control strategies and the optimization of future treatments.

Eficácia in vitro de desinfetantes comerciais utilizados no pré e pós-dipping frente a Staphylococcus spp. isolados em rebanhos leiteiros / In vitro efficacy of commercial disinfectants used in pre-and post-dipping against Staphylococcus spp. isolated from dairy cattle

The objective of this study was to evaluate the in vitro efficacy of commercial disinfectants used in pre- and post-dipping, against Staphylococcus spp. isolated from milk originating from dairy cattle farms in the Wasteland and Forest Zone of Alagoas, Brazil. We used iodine (0.57%), chlorhexidine (2.0%), chlorine (2.5%) and quaternary ammonium compound (4.0%) at concentrations indicated, conventionally used as commercial disinfectants before and after dipping. We analyzed a total of 97 isolates of Staphylococcus spp. identified as S. aureus (16), coagulase positive Staphylococcus (7) and coagulase-negative Staphylococcus (74). The disinfectants were evaluated at three different times (15", 30" and 60"). We found that 56.3% of Staphylococcus aureus was sensitive to iodine, 68.8% to chlorine, 87.5% to chlorhexidine, and 37.5% to the compound of ammonia, in time 60". As for coagulase positive staphylococci (CPS), 100% of the isolates was resistant to chlorhexidine, 85.7% to the ammonia compound, 57.1% to chlorine, and 42.9% iodine, in time 60". Regarding coagulase negative staphylococci (CNS), 91.9% was sensitive to chlorhexidine, 70.3% to chlorine, 66.2% to iodine, and 24.3% the ammonium compound, at time 60". It is concluded from this study that the greatest disinfectant activity in vitro was with chlorhexidine and chlorine for S. aureus, with iodine and chlorine for SCP, and with chloride and chlorhexidine for SCN. Due to variations in the sensitivity and resistance profile found, it is necessary for regular assessments of the effectiveness of disinfectants used on the farms, to observe the effectiveness of the product and thus ensure the control of mastitis in the herd.

Objetivou-se com esse estudo avaliar a eficácia in vitro de desinfetantes comerciais utilizados no pré e pós- -dipping, frente a Staphylococcus spp. isolados do leite de vacas procedentes de propriedades leiteiras do Agreste e Zona da Mata do Estado de Alagoas. Foram utilizados iodo (0,57%), clorexidine (2,0%), cloro (2,5%) e composto de amônio quaternário (4,0%), nas concentrações indicadas, como desinfetantes comerciais usados convencionalmente no pré e pós-dipping. Analisou-se um total de 97 isolados de Staphylococcus spp. identificados como S. aureus (16), Staphylococcus coagulase positiva (7) e Staphylococcus coagulase negativa (74). Os desinfetantes foram avaliados em três tempos distintos (15", 30" e 60"). Observou-se que 56,3% de Staphylococcus aureus foram sensíveis ao iodo, 68,8% sensíveis ao cloro, 87,5% à clorexidine e 37,5% ao composto de amônia no tempo de 60". Quanto aos Staphylococcus coagulase positiva (SCP), 100% dos isolados foram resistentes ao clorexidine, 85,7% ao composto de amônio, 57,1% ao cloro, e 42,9 resistentes ao iodo no tempo de 60". Em relação aos Staphylococcus coagulase negativa (SCN) foi observado 91,9% de sensibilidade ao clorexidine, 70,3% sensíveis ao cloro, 66,2% ao iodo e 24,3% sensíveis ao composto de amônio no tempo de 60". Conclui-se com esse estudo que a maior atividade desinfetante in vitro foi verificada para clorexidine e cloro frente aos S. aureus, iodo e cloro para os SCP e clorexidine e cloro para os SCN. Devido às variações no perfil de sensibilidade e resistência encontradas, é necessária a avaliação regular da eficiência dos desinfetantes usados nas propriedades, com o intuito de observar a eficácia do produto e assim garantir o controle da mastite no rebanho.