Vanessa Gomes da Silva

Aquaculture is one of the sectors of animal husbandry with the fastest growth rate. However, the increase in the sector’s production chain without proper management can result in factors that favor the development of diseases, especially infectious diseases caused by bacteria. Many factors, such as agriculture or industry resides, improper use of antibiotics in animals or humans, have contributed to increased environmental pressure and the appearance of antibiotic-resistant bacteria, while residues from these drugs can remain in the carcasses and in water a risk to public and environmental health. From that, we identified the bacterial genus/species and their bacterial resistance to antibiotics from samples received from fish disease outbreaks for bacteriosis diagnosis between January 2017 and October 2020. Isolated bacteria were subjected to the Kirby and Bauer sensitivity test for five classes of antibiotics (penicillins, fluoroquinolones, aminoglycosides, amphenicols, and tetracyclines). Of the 181 analyzed outbreaks, 232 bacteria were isolated, including Streptococcus spp., Aeromonas spp., Edwardsiella spp., Plesiomonas shigelloides, Pseudomonas aeruginosa, Chromobacterium violaceum, Flavobacterium spp., Citrobacter spp., Enterococcus spp., Vibrio spp., Enterobacter spp., Chryseobacterium meningosepticum. Of the 232 bacteria, 40 strains were classified as multidrug resistant (MDR), with Plesiomonas shigelloides, Aeromonas spp., and Edwardsiella spp. representing more than half of this number (22/total). With several bacteria demonstrating resistance to Brazilian aquaculture-legalized drugs (tetracycline and florfenicol), it is mandatory to research, not only for alternatives to the use of antibiotics, but also for other drugs effective against the main circulating bacterial pathogens. In addition, vigilance over the occurrence of resistant bacteria is necessary, considering the appearance of zoonotic bacteria with multi-resistant characteristics, becoming a public health concern.

The aim of this work was to verify the presence of microbiological indicators and the biofilm production capacity of the microorganisms found on the surfaces, in a milk processing plant, in order to estimate the hygienic sanitary conditions. For this purpose, a Good Manufacturing Practices (GMP) checklist and microbiological analysis were applied. Through to use of GMP checklist was possible to determine sites for sample collection and to establish the respective microbiological analyses. The presence of Enterococcus and high total bacterial counts (TBC) suggested the presence of biofilms on equipment, being also evidenced by the microplate technique. Although acceptable results were obtained for pasteurized milk, the indicators show that the risk was present in this dairy processing plant.

Trichinella spiralis causes severe infections in humans, resulting in various clinical symptoms and even death, in several countries worldwide. Human trichinellosis has been reported in 55 countries, and mainly affects certain ethnic groups and tourists. It is caused by the ingestion of raw, undercooked meat or pork, or their by-products containing parasitic larvae. Infections in swine especially occur due to the parasitic contamination of food containing animal products, predation by rodents and other animals infected with T. spiralis, and due to the frequent habit of cannibalism in intensive production systems. This study aimed to evaluate the prevalence of T. spiralis in pig carcasses from a slaughterhouse located in the midwestern region of Paraná State, Brazil. Pools of 100 g of diaphragm, containing at least 1 g of tissue from each test animal, were collected, ground, and subjected to acid digestion with pepsin (1:10,000) and 25% hydrochloric acid. Sampling was performed in accordance to the methodology recommended by the European Union. All the 735,902 samples collected between 2010 and 2013, and in 2018, were negative for Trichinella spp. larvae. The pigs came from 483 farms from 90 municipalities from the three states of southern Brazil (Paraná, Santa Catarina and Rio Grande do Sul). The absence of the parasite in different animal species, reported by surveys conducted in Brazil, could confirm the country as free from trichinellosis. Although T. spiralis is not endemic to Brazil, it is necessary to subject the meat of adult pigs slaughtered here and exported to other countries to inspections and parasitological examinations. It is therefore necessary to continually inspect pig carcasses for T. spiralis in slaughterhouses worldwide.

Entre as principais doenças infecciosas em peixes, as causadas por organismos zoospóricos são importantes, especialmente a saprolegníase. Essas doenças podem afetar poucos animais ou até mesmo toda a população do ambiente de produção. O uso de tratamentos alternativos para doenças infecciosas em animais aquáticos tem se mostrado eficaz. Evita a mortalidade de parte da cultura, bem como a contaminação da água por componentes químicos. Dentro deste cenário, destaca-se o uso de plantas, principalmente plantas alimentícias não convencionais (PANCs). O objetivo deste trabalho foi avaliar o efeito dos extratos aquosos de Luffa cylindrica, Xanthosoma sagittifolium e Momordica charantia sobre o crescimento micelial de Saprolegnia spp. Os extratos obtidos da maceração de folhas secas e moídas foram incorporados em ágar batata dextrose (BDA), nas concentrações de 0, 5, 15, 25 e 50%. Mais tarde, os discos de papel de filtro contendo o micélio de Saprolegnia spp. foram aplicados no ágar e incubados a 25°C. As avaliações foram realizadas a cada 24 horas, por 10 dias. No estudo, todas as concentrações do extrato de M. charantia tiveram ação inibitória sobre o crescimento micelial da ordem de 75% de Saprolegnia spp., podendo ser considerada uma alternativa promissora para o controle desse patógeno.

Diversos estudos são desenvolvidos com o objetivo de buscar novas tecnologias, como a utilização de plantas alimentícias não convencionais no controle de fitopatógenos. O objetivo desta pesquisa foi avaliar o efeito de extratos vegetais de Luffa cilyndrica, Xanthosoma sagittifolium e Momordica charantia, em diferentes concentrações, sobre o crescimento micelial do fungo Fusarium sp. O procedimento foi realizado a partir dos extratos obtidos da maceração de folhas secas e moídas, incorporados ao meio de cultivo Batata Dextrose Ágar (BDA), nas concentrações de 0, 5, 15, 25 e 50%. Subsequentemente, discos de papel-filtro contendo micélio de Fusarium sp. foram aplicados sobre o ágar e mantidos em estufa a 25 °C. Após 48 horas de incubação, as avaliações foram realizadas em intervalos de 24 horas, permanecendo por sete dias, ou até o momento em que o micélio de Fusarium sp. da placa controle (0%) alcançou os bordos da placa de Petri. O extrato de Xanthosoma sagittifolium a 50% e todas as concentrações do extrato de Momordica charantia, com exceção da 5%, tiveram ação inibitória ao crescimento micelial de Fusarium sp., podendo ser consideradas alternativas diferenciadas e promissoras no controle do fitopatógeno.

The pathogenesis of a Streptococcus agalactiae was evaluated in a three-period experiment. Two groups of 40 fishes were intraperitoneally (i.p.) challenged in each experimental period with different infective doses of the pathogen. Doses varied from 1.0 x 10(6) to 1.5 x 10(8) CFU/fish. One group of 40 tilapia i.p. injected with tryptic soy broth (TSB) was used as a control group in each period. Mortalities varied from 67.5% in group 8 (infective dose 1.0 x 10(6) CFU/fish) to 90.0% in group 1 (infective dose 1.5 x 10(8) CFU/fish). Significant differences in mortalities were found only between group 8 and each of the other groups, except group 5 (infective dose 6.0 x 10(6) CFU/fish; mortality 75.0%). The highest mortality coefficients were observed in days 1-2 after inoculation (accumulated mortality 44.4%), and a second peak of mortality occurred at days 6-7. Challenged fishes from all the groups showed alterations in behaviour and similar clinical signs. These were anorexia, lethargy, erratic swimming, exophthalmia and ascites. Macroscopically, skin hemorrhage, splenomegaly, hepatomegaly with organ paleness and visceral adherences were observed. S. agalactiae was re-isolated from all the fishes from the experimental groups submitted to bacteriological examination. The illness observed in tilapia naturally infected with S. agalactiae was experimentally reproduced in this study, and the clinical signs produced were similar to those reported from the natural infections.

Tilapia aquaculture is one of the fastest-growing segments of fish production in Brazil. Nile tilapia (Oreochromis niloticus) is largely cultivated in the state of Parana, where Streptococcus agalactiae is the cause of severe disease outbreaks. The objective of this paper was to evaluate an inactivated S. agalactiae vaccine in tilapia for the control of streptococcal disease outbreaks. Tilapia, weighing approximately 20 g each, were intraperitoneally (i.p.) inoculated with 0.1 mL of the vaccine at a dose of 2.0 × 10⁸ colony-forming unit (CFU) mL⁻¹. One group of tilapia (treatment 1) received one vaccine dose, and the other group of tilapia (treatment 2) received two doses, with an interval of 21 days. The control group was i.p. inoculated with 0.1 mL tryptic soy broth fish⁻¹. Immunized and control tilapia were i.p. challenged with 0.1 mL of 3.0 × 10⁷ CFU mL⁻¹ at 30 days post vaccination. The fish were monitored daily for disease signs and for mortality for 16 days post challenge. A statistically significant difference (P=0.0045) was found between the mortality of treatments 1 and 2. The value of relative per cent of survival of 83.6% and 96.4%, respectively, indicate that this vaccine was efficient in Nile tilapia.