Antimicrobial and bactericidal impacts of Bacillus amyloliquefaciens CECT 5940 on fecal shedding of pathogenic bacteria in dairy calves and adult dogs.

Two experiments were carried out to evaluate the bactericidal impacts of Bacillus amyloliquefaciens CECT 5940 on the shedding of faecal pathogenic bacteria in dairy calves (Experiment 1) and in adults dogs (experiment 2). In the calves experiment, a completely randomized design was used to investigate the faecal bacteria profile of Holstein dairy calves fed with either pasteurized waste milk (PWM; n = 9) or a formulated non-medicated milk replacer (NMR; n = 9) for 60 d. The NMR containing sodium-butyrate and the active probiotic B. amyloliquefaciens CECT 5940. In the dogs experiment, addition of same probiotic (i.e., B. amyloliquefaciens CECT 5940) was carried out in two stages. The first stage started from day 7-37, and the second from day 44-71. The assessment of faecal score measured on day 22, 37, 42, 57, 71 and 77 to determine the texture of the stools. Calves received PWM consumed (P < 0.05) more starter feed between day 16 and day 45. The calves fed NMR had more moisture faeces and less cough reflux than the PWM-calves. Feeding NMR to calves increased faecal Klebsiella oxytoca and Proteus vulgaris counts in comparison to PWM-calves. The administration of B. amyloliquefaciens CECT 5940 to the dog diet has no significant effect on the hardness of the stool. Meanwhile, the bacillus count increases while the coliforms count decreases upon B. amyloliquefaciens CECT 5940 administration. This reveals that B. amyloliquefaciens CECT 5940 survived the gastrointestinal passage and rapidly colonized the dog intestine, which could positively affect the metabolism and composition of the intestinal microflora. These results show that B. amyloliquefaciens are a promising probiotic with an antimicrobial and bactericidal activities against the intestinal pathogenic bacteria for dairy calves and adult dogs.

Anti-staphylococcal properties of four plant extracts against sensitive and multi-resistant bacterial strains isolated from cattle and rabbits.

The aim of this study is to investigate the biopotency of methanolic extracts of Vitex mollis, Psidium guajava, Dalbergia retusa, and Crescential alata leaves against various staphylococcal strains isolated from cattle and rabbits. Methicillin-resistant S. aureus strains were isolated from cattle, while other strains were isolated from rabbits using standard methodology. The total phytochemical phenolic and saponins contents were obtained being the main groups of the antinutritional factors. The antimicrobial activity of the extracts against the standard culture of S. aureus (control) and S. aureus isolated from cattle and rabbits were investigated comparatively relative to that of oxacillin. It was found that both the control S. aureus and the isolated S. aureus are susceptible to all the four plant extracts, and sensitive to oxacillin. Of all the S. aureus including the control, MRSA2 is the most susceptible to all the extracts at 1000 µg/mL, except that of V. mollis where it is the least susceptible. Among all the plant extracts, P. guajava is the most active against MRSA2 and SOSA2. Therefore, the isolates from cattle (MRSA1 and MRSA2) are more susceptible to all the plant extracts than the isolates from rabbits. Among all the rabbit isolates, CoNS3 is the least susceptible to the extracts. Since all the plant extracts exhibit remarkable inhibitory activities against all the S. aureus strains, they are promising towards the production of therapeutic drugs.

Prevalence of bovine subclinical mastitis, its etiology and diagnosis of antibiotic resistance of dairy farms in four municipalities of a tropical region of Mexico.

A region-wide survey was conducted in the tropical area of Tierra Caliente, State of Guerrero, Mexico to estimate the prevalence of subclinical bovine mastitis (SCM), distribution of mastitis pathogens, and in vitro antimicrobial susceptibility of different mastitis pathogens in dairy farms. In total, 1036 quarter milk samples were obtained from 259 cows at 87 different dairy farms. Collected quarter milk samples were submitted for California Mastitis Test (CMT), bacteriological examination, and testing for antimicrobial susceptibility. Overall prevalence of SCM in the studied area was 20.5 %. Prevalence in the different regions was as follows: 28 % in Arcelia municipality, 21 % in Tlalchapa municipality, 19.4 % in Pungarabato municipality, and 14.3 % in Finch Cutzamala municipality. Of all positive isolates, 97.5 % were Gram-negative bacteria. Moreover, of all positive isolates, 37.5 % were Proteus vulgaris, 25 % Salmonella spp., 12.5 % Enterobacter aerogenes, and 10 % Escherichia coli. Klebsiella pneumonia and E. coli were sensitive for netilmicin antimicrobial. However, E. coli was sensitive for pefloxacin and gentamicin with a sensitivity for pefloxacin for E. aerogenes, while Staphylococci were sensitive for gentamicin and dicloxacillin. It could be concluded that practices such as the implementation of mastitis control programs, improved milking hygiene together with an intramammary treatment with netilmicin, pefloxacin, and gentamicin antimicrobials should be considered for mastitis prevention in the study area of Tierra Caliente, in the tropical area of Guerrero, Mexico.

Resistencia antibiótica de genotipos de cepas de Salmonella spp de cerdos sacrificados en rastros del Estado de México / Antibiotic resistance of Salmonella spp strain genotypes isolated from pigs slaughtered at abattoirs in the Estado de Mexico

Multiresistant Salmonella serovar Typhimurium strains are a worldwide problem in animal and human health. The aim of this study was to determine the frequency of some Salmonella spp resistance genes (cmlA/tetR, PSE-1, TEM, Sip B/C) in strains isolated from pigs slaughtered at abattoirs in the Estado de Mexico. Of 87 analyzed strains 22 (25.28%) had phenotypical resistance to chloramphenicol (30 μg), 15 (17.24%) to ampicillin (10 μg) and 54 (62.07%) to sulfamethoxazole (60 μg). The phenotypical and genotypical relation of the 87 strains was: of the 22 chloramphenicol resistant strains only 14 (63.63%) expressed the cmlA/tetR resistance gene, and of the 65 strains non-resistant to chloramphenicol only 36 (55.38%) expressed the cmlA/tetR resistance gene. Regarding the 15 ampicillin resistant strains only 2 (13.33%) were carriers of the PSE-1 gene and 7 (46.66%) presented the TEM gene; both genes confer genotypical ampicillin resistance. Of 72 non-resistant ampicillin strains, 11 (15.27%) carried the TEM gene which confers ampicillin resistance. Two Salmonella strains (2.28%) belonged to phagotype DT104. Strains not showing phenotypical resistance but carrying resistance genes have not been exposed to selection by competition, although they possess the mechanism to express such resistance.

La aparición de cepas multirresistentes de Salmonella Typhimurium es un problema mundial, tanto en salud animal como en salud pública. El objetivo del presente trabajo fue determinar la frecuencia de algunos genes de resistencia (cmlA/tetR, PSE-1, TEM, Sip B/C) en cepas de Salmonella spp aisladas de cerdos en rastros del Estado de México. De las 87 cepas analizadas, 22/87 (25.28%) mostraron resistencia al cloranfenicol (30 μg), 15/87 (17.24%) a la ampicilina (10 μg) y 54/87 (62.07%) fueron resistentes al sulfametoxazol (60 μg). La relación fenotípica y genotípica de las 87 cepas analizadas fue: de las 22 cepas que presentaron resistencia fenotípica al cloranfenicol, sólo 14/22 (63.63%) expresaron el gen de resistencia cmlA/tetR, y de las 65 cepas que manifestaron sensibilidad al cloranfenicol, 36/65 (55.38%) expresaron el gen de resistencia cmlA/tetR. De las 15 cepas que expresaron resistencia a la ampicilina, sólo 2/15 (13.33%) mostraron el gen PSE-1, y 7/15 (46.66%) presentaron el gen TEM, ambos genes confieren resistencia genotípica a la ampicilina. De las 72 cepas que manifestaron sensibilidad a la ampicilina, 11 (15.27%) mostraron el gen TEM, el cual da resistencia a la ampicilina. De las 87 cepas de Salmonella sólo 2/87 (2.28%) expresaron el fagotipo DT104. Las cepas que son portadoras de genes de resistencia, pero no la manifiestan fenotípicamente, no han sido expuestas a una selección por competencia, por lo tanto, no expresan la resistencia fenotípica, pero cuentan con el mecanismo necesario para expresarla.

Evaluación de la capacidad inmunogénica y protectora de antígenos de Pasteurella multocida, obtenidos de aislados de casos clínicos / Immunogenic evaluation and protection of Pasteurella multocida antigens isolated from clinical cases

The immunogenic protection response to four P. multocida isolations obtained from clinical cases and a reference strain was studied. Isolations were proven as three different immunogens: complete antigen (Ag), washed Ag and culture supernatant. They were subcutaneously administered in SPF light White Leghorn hens. Immune response was evaluated using ELISA test and challenge test evaluated protection response. The ANOVA and Tukey test did not show statistical differences between groups. All isolations using different vaccines induced high protection levels ranging from 87 to 100%. This study indicates that immunization using these three immunogens induce an effective response against P. multocida challenge with the best protection when culture supernatant is used.

Se investigaron los niveles de anticuerpos y la capacidad protectora de cuatro diferentes aislados de P. multocida, obtenidos de casos clínicos y de una cepa de referencia. Los aislados se evaluaron como tres inmunógenos diferentes: antígeno completo (Ag), Ag lavado y el sobrenadante del cultivo. Se administraron en aves ligeras de la raza White Leghorn (SPF) por vía subcutánea. Los niveles de anticuerpos se determinaron mediante el ensayo de ELISA y la protección, desafiando las aves con los respectivos aislados utilizados para vacunación. ANDEVA y la prueba de Tukey no mostraron diferencias estadísticas entre grupos. Todos los aislados en los diferentes tipos de preparación de la vacuna indujeron altos niveles de protección, entre el 87% y 100%. Este estudio indica la efectividad de los diferentes aislados clínicos en la protección de las aves desafiadas.