PESQUISA VETERINÁRIA BRASILEIRA

Abstract in English:

ABSTRACT.- Schmidt V., Pinto A.T., Schneider R.N. Silva F.F.P. & Mello F.A. 2009. [Characterization of subclinical mastitis in dairy goats herds raised on an organic system in Rio Grande do Sul.] Caracterização da mastite subclínica em caprinos produzidos em sistema orgânico no Rio Grande do Sul. Pesquisa Veterinária Brasileira 29(9):774-778. Faculdade de Veterinária, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9090, Porto Alegre, RS 91540-000, Brazil. E.mail: veronica.schmidt@ufrgs.br Milk and derivates are recognized as vehicle of different pathogens for humans. These micoorganisms may manifest as post-milking contamination or as in infections in the animal itself, particularly in mastitis. The aim of present study was characterizes the occurrence of mastitis and management aspects in dairy-goats raised in three farms of organic milk. The correlation between mastitis and goat husbandry was also investigated. The clinical exam of the mammary glands of 64 dairy-goats did not reveal the presence of clinical mastitis. Nevertheless, the California Mastitis Test (CMT) identified 54 (22.7%) reactive mammary halves (+ or ++). From 238 milk samples collected, 37 (15.6%) were positive for bacterial isolates. Coincident positive results for bacterial isolate tests and CMT were observed in only eight samples, which indicate a sensitivity index of 21.6% for the caprine subclinical mastitis diagnosis test. Coagulase-negative staphylococci (CNS) were identified as the most frequent pathogen in milk samples (83.8%). The in vitro sensitivity test revealed CNS strains resistant to cotrimoxazole (50%), ampicillin (48.1%), nitrofurantoine (7.7%), cefaclor (7.14%), and oxacilline (3.85%). Cefalotine, gentamicin, neomycin, streptomycin, and tetracycline were the most effective drugs. No correlation was observed between the occurrence of subclinical mastitis and race, lactation period, drinking water quality in farms, or milking system as adopted in the present study.

• Mastitis coagulase-negative staphylococci mastite Staphylococcus coagulase negativo

Abstract in Portuguese:

RESUMO.- Schmidt V., Pinto A.T., Schneider R.N. Silva F.F.P. & Mello F.A. 2009. [Characterization of subclinical mastitis in dairy goats herds raised on an organic system in Rio Grande do Sul.] Caracterização da mastite subclínica em caprinos produzidos em sistema orgânico no Rio Grande do Sul. Pesquisa Veterinária Brasileira 29(9):774-778. Faculdade de Veterinária, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9090, Porto Alegre, RS 91540-000, Brazil. E.mail: veronica.schmidt@ufrgs.br O leite e derivados são reconhecidos como veículos de patógenos para humanos, secundário a contaminação pós-ordenha ou de infecções do próprio animal, particularmente na mastite. Foi estudada a ocorrência de mastite e aspectos do manejo em cabras de três propriedades criadas em sistema orgânico. O exame clínico da glândula mamária de 64 cabras em diferentes períodos de lactação, não acusou a presença de mastite clínica. Entretanto, o Califórnia Mastitis Test (CMT) identificou 54 (22,7%) metades mamárias reagentes (+ ou ++). Foram colhidas 238 amostras de leite, das quais houve isolamento bacteriano em 37 (15,6%). Em apenas oito amostras houve coincidência entre o isolamento bacteriano e o resultado do CMT, indicando sensibilidade de 21,6% para este teste no diagnóstico de mastite subclínica em caprinos. Staphylococcus coagulase negativa (SCN) foi o microrganismo mais freqüente (83,8%). O teste de sensibilidade microbiana in vitro revelou resistência das linhagens de SCN ao cotrimoxazol (50%), ampicilina (48,1%), nitrofurantoína (7,7%), cefaclor (7,14%) e oxacilina (3,85%). Cefalotina, gentamicina, neomicina, estreptomicina e tetraciclina foram os antimicrobianos mais efetivos frente aos isolados. Não se evidenciou relação entre a ocorrência de mastite subclínica com a raça, a fase de lactação, sistema de ordenha ou qualidade da água utilizada nas propriedades.

Abstract in English:

ABSTRACT.- Pereira I.A., Soares L.C., Coelho S.M.O., Pribul B.R. & Souza M.M.S. 2009. [Susceptibility to azithromycin of bacteria isolated from infectious processes in dogs and cats.] Suscetibilidade à azitromicina de isolados bacterianos de processos infecciosos em cães e gatos. Pesquisa Veterinária Brasileira 29(2):153-156. Departamento de Microbiologia e Imunologia Veterinária, Universidade Federal Rural do Rio de Janeiro, Seropédica, RJ 23890-000, Brazil. E-mail: miliane@ufrrj.br The susceptibility pattern to azithromycin of bacterial pathogens from various infectious sites, and the in vitro activity and minimum inhibitory concentration (MIC) of azithromycin were studied. Tests such as disc diffusion and broth microdilution detected respectively 48.6% and 55% of resistant Staphylococcus spp., and 55.3% and 72.7% resistant gram-negative rods. MIC50 for S. aureus was 4.0mg/mL, that for S. intermedius was 1.0mg/mL, for coagulase-negative Staphylococcus e”512mg/mL, and for gram-negative rods 256mg/mL. Fifteen percent (9/60) of oxacilin-resistant, multidrug-resistant and mecA-positive Staphylococcus spp. isolates were also azithromycin resistant. The dissemination of multidrug resistant bacteria points out to the need of antimicrobial evaluation activity in order to select the best indicated drug and thus minimizing therapeutic failures in veterinary practice.

• Diseases of dogs and cats bacterial diseases bacterial antibiotic resistance azithromycin

Abstract in Portuguese:

ABSTRACT.- Pereira I.A., Soares L.C., Coelho S.M.O., Pribul B.R. & Souza M.M.S. 2009. [Susceptibility to azithromycin of bacteria isolated from infectious processes in dogs and cats.] Suscetibilidade à azitromicina de isolados bacterianos de processos infecciosos em cães e gatos. Pesquisa Veterinária Brasileira 29(2):153-156. Departamento de Microbiologia e Imunologia Veterinária, Universidade Federal Rural do Rio de Janeiro, Seropédica, RJ 23890-000, Brazil. E-mail: miliane@ufrrj.br The susceptibility pattern to azithromycin of bacterial pathogens from various infectious sites, and the in vitro activity and minimum inhibitory concentration (MIC) of azithromycin were studied. Tests such as disc diffusion and broth microdilution detected respectively 48.6% and 55% of resistant Staphylococcus spp., and 55.3% and 72.7% resistant gram-negative rods. MIC50 for S. aureus was 4.0mg/mL, that for S. intermedius was 1.0mg/mL, for coagulase-negative Staphylococcus e”512mg/mL, and for gram-negative rods 256mg/mL. Fifteen percent (9/60) of oxacilin-resistant, multidrug-resistant and mecA-positive Staphylococcus spp. isolates were also azithromycin resistant. The dissemination of multidrug resistant bacteria points out to the need of antimicrobial evaluation activity in order to select the best indicated drug and thus minimizing therapeutic failures in veterinary practice.

Abstract in English:

Zafalon L.F., Nader Filho A., Oliveira J.V. & Resende F.D. 2005. [Electrical conductivity and chloride concentration of milk as auxiliary diagnostic methods in bovine subclinical mastitis.] Comportamento da condutividade elétrica e do conteúdo de cloretos do leite como métodos auxiliares de diagnóstico na mastite subclínica bovina. Pesquisa Veterinária Brasileira 25(3):159-163. Depto Medicina Veterinária Preventiva e Reprodução Animal, FACVJ, Unesp - Campus de Jaboticabal, Via de Acesso Prof. Paulo Donato Castellane s/no, Jaboticabal, SP 14884-900, Brazil. E-mail: zafalon@iz.sp.gov.br Electrical conductivity measured by a hand-held meter and chloride concentration of milk were studied as auxiliary methods for diagnosis of bovine subclinical mastitis in the identification of affected mammary quarters where Staphylococcus aureus and Corynebacterium sp were later isolated. Tests were made during 2 years in Holstein cows of a dairy farm producing type C milk, where milking was performed once a day. Sensitivities of electrical conductivity and chloride concentration tests from mammary quarters, where Corynebacterium sp was isolated (65.3% and 78.3%, respectively), were superior to the found in mammary quarters where S. aureus was identified (55.4% and 68.2%, respectively). The efficacies of the two diagnostic tests were similar. Statistical significance was demonstrated with regression analysis of both tests of healthy mammary quarters and subclinical mastitis quarters infected with Staphylococcus aureus.

• Bovine subclinical mastitis electric conductivity chloride level Staphylococcus aureus Corynebacterium sp.

Abstract in Portuguese:

Zafalon L.F., Nader Filho A., Oliveira J.V. & Resende F.D. 2005. [Electrical conductivity and chloride concentration of milk as auxiliary diagnostic methods in bovine subclinical mastitis.] Comportamento da condutividade elétrica e do conteúdo de cloretos do leite como métodos auxiliares de diagnóstico na mastite subclínica bovina. Pesquisa Veterinária Brasileira 25(3):159-163. Depto Medicina Veterinária Preventiva e Reprodução Animal, FACVJ, Unesp - Campus de Jaboticabal, Via de Acesso Prof. Paulo Donato Castellane s/no, Jaboticabal, SP 14884-900, Brazil. E-mail: zafalon@iz.sp.gov.br Electrical conductivity measured by a hand-held meter and chloride concentration of milk were studied as auxiliary methods for diagnosis of bovine subclinical mastitis in the identification of affected mammary quarters where Staphylococcus aureus and Corynebacterium sp were later isolated. Tests were made during 2 years in Holstein cows of a dairy farm producing type C milk, where milking was performed once a day. Sensitivities of electrical conductivity and chloride concentration tests from mammary quarters, where Corynebacterium sp was isolated (65.3% and 78.3%, respectively), were superior to the found in mammary quarters where S. aureus was identified (55.4% and 68.2%, respectively). The efficacies of the two diagnostic tests were similar. Statistical significance was demonstrated with regression analysis of both tests of healthy mammary quarters and subclinical mastitis quarters infected with Staphylococcus aureus.

Abstract in English:

Simionatto S., Vaz E.K., Michelon A., Seixas F.K., Dellagostin O.A. 2005. [Development and evaluation of new strategies for immunization against swine colibacillosis.] Desenvolvimento e avaliação de novas estratégias de imunização contra colibacilose suína. Pes-quisa Veterinária Brasileira 25(2):84-90. Laboratório de Biologia Molecular, Centro de Bio-tecnologia, UFPel, Campus Capão do Leão, Cx. Postal 354, Pelotas, RS 96010-900, Brazil. E-mail: ssimionatto@bol.com.br Swine colibacillosis caused by enterotoxigenic Escherichia coli remains one of the main sanitary problems in pig farms. The recombinant DNA technology offers the possibility of developing new immunization strategies. This paper describes the development of a subunit vaccine through the expression and purification of the E. coli K88 FaeC fimbrial protein. The gene that codes for this antigen was amplified by PCR and cloned into an E. coli expression vector fused to a 6X histidine tag. The recombinant protein was purified by affinity chromatography and used for mice immunization. In parallel, the same gene was cloned into an eucariotic expression vector with the addition of the Kozak sequence for improving translation of this gene in muscle cells. The resulting plasmid named pUP310 was purified in large scale and used to immunize mice. The immune response afforded by both forms of immunization was monitored by ELISA. There was an immune response in mice inoculated with pUP310 and purified FaeC. It was possible to detect anti-FaeC antibodies 42 days after the first inoculation. The antibody titer increased with time, being still detectable 7 months after the first inoculation. It is concluded that recombinant FaeC and pUP310 are potential tools for immunization of swine against E. coli K88.

• Swine colibacillosis FaeC Escherichia coli DNA vaccine recombinant vaccine.

Abstract in Portuguese:

Simionatto S., Vaz E.K., Michelon A., Seixas F.K., Dellagostin O.A. 2005. [Development and evaluation of new strategies for immunization against swine colibacillosis.] Desenvolvimento e avaliação de novas estratégias de imunização contra colibacilose suína. Pes-quisa Veterinária Brasileira 25(2):84-90. Laboratório de Biologia Molecular, Centro de Bio-tecnologia, UFPel, Campus Capão do Leão, Cx. Postal 354, Pelotas, RS 96010-900, Brazil. E-mail: ssimionatto@bol.com.br Swine colibacillosis caused by enterotoxigenic Escherichia coli remains one of the main sanitary problems in pig farms. The recombinant DNA technology offers the possibility of developing new immunization strategies. This paper describes the development of a subunit vaccine through the expression and purification of the E. coli K88 FaeC fimbrial protein. The gene that codes for this antigen was amplified by PCR and cloned into an E. coli expression vector fused to a 6X histidine tag. The recombinant protein was purified by affinity chromatography and used for mice immunization. In parallel, the same gene was cloned into an eucariotic expression vector with the addition of the Kozak sequence for improving translation of this gene in muscle cells. The resulting plasmid named pUP310 was purified in large scale and used to immunize mice. The immune response afforded by both forms of immunization was monitored by ELISA. There was an immune response in mice inoculated with pUP310 and purified FaeC. It was possible to detect anti-FaeC antibodies 42 days after the first inoculation. The antibody titer increased with time, being still detectable 7 months after the first inoculation. It is concluded that recombinant FaeC and pUP310 are potential tools for immunization of swine against E. coli K88.

Abstract in English:

Hofer E. & Reis C.M.F. 2005. [Species and serovars of Listeria isolated from sick and clinically healthy animals in Brazil.] Espécies e sorovares de Listeria isolados de animais doentes e portadores no Brasil. Pesquisa Veterinária Brasileira 25(2):79-83. Laboratório de Zoonoses Bacterianas, Depto Bacteriologia, Instituto Oswaldo Cruz/FIOCRUZ, Rio de Janeiro, RJ 21045-900, Brazil. E-mail: ehofer@ioc.fiocruz.br Two hundred fourty-six strains of the genus Listeria were isolated from sick and clinically healthy animals, collected in three different regions of Brazil during 1971-2000. About 88.2% (217 cultures) yielded Listeria species from faecal specimens of healthy cattle and 29 strains (11.7%) were isolated from sick animals: 15 (6.0%) from central nervous system (CNS) and 14(5.6%) were from otherwise sterile sites. Phenotyping techniques were used to characterize the Listeria isolates. The commonest were L. innocua 6a and non-typable (140/56.9%), L. monocytogenes 4a (37/15.0%) and 4b (22/8.9%), originated mainly from stools of healthy cattle. From sick animals the predominant species and serovars were L. monocytogenes 4b (14/5.6%), and the higher incidence was observed in ruminants (12/4.8%) and 8/3.2% of the serovar 1a from other animal species (rodents and canines) mainly isolated from CNS samples.

• Listeria species serovars sick and healthy animals.

Abstract in Portuguese:

Hofer E. & Reis C.M.F. 2005. [Species and serovars of Listeria isolated from sick and clinically healthy animals in Brazil.] Espécies e sorovares de Listeria isolados de animais doentes e portadores no Brasil. Pesquisa Veterinária Brasileira 25(2):79-83. Laboratório de Zoonoses Bacterianas, Depto Bacteriologia, Instituto Oswaldo Cruz/FIOCRUZ, Rio de Janeiro, RJ 21045-900, Brazil. E-mail: ehofer@ioc.fiocruz.br Two hundred fourty-six strains of the genus Listeria were isolated from sick and clinically healthy animals, collected in three different regions of Brazil during 1971-2000. About 88.2% (217 cultures) yielded Listeria species from faecal specimens of healthy cattle and 29 strains (11.7%) were isolated from sick animals: 15 (6.0%) from central nervous system (CNS) and 14(5.6%) were from otherwise sterile sites. Phenotyping techniques were used to characterize the Listeria isolates. The commonest were L. innocua 6a and non-typable (140/56.9%), L. monocytogenes 4a (37/15.0%) and 4b (22/8.9%), originated mainly from stools of healthy cattle. From sick animals the predominant species and serovars were L. monocytogenes 4b (14/5.6%), and the higher incidence was observed in ruminants (12/4.8%) and 8/3.2% of the serovar 1a from other animal species (rodents and canines) mainly isolated from CNS samples.

Abstract in English:

Penatti M.P.A., Silva A.S., Valadares G.F. & Leite D.S. 2005. Occurrence of F42 colonization factor in Escherichia coli strains isolated from piglets with diarrhea. Pesquisa Veterinária Brasileira 25(1):31-33. Depto Microbiologia e Imunologia, Instituto de Biologia, Unicamp, Campinas, SP 13081-970, Brazil. E-mail: domingos@unicamp.br The objective of this study was to determine the presence of the colonization factor F42 in 168 strains of Escherichia coli isolated from diarrheic stools of newborn piglets. The presence of F42 in 12 (7.1%) strains was detected with the agglutination test. Through the Polymerase Chain Reaction (PCR) of F42 positive strains, gene encoding enterotoxins (ST-I, ST-II, LT-I and LT-II) were detected. The finding of ST-I/ST-II genes in 50% of the strains, ST-I (16%) and ST-II (25%) indicates a strong association of FC F42 with heat-stable enterotoxins (91%). In contrast, the thermolabile enterotoxin (LT-I and LT-II) genes were not detected. Serogroups of F42 positive strains were determined, serogroup O8 being the most prevalent (41,7%). Other serogroups, as there are O9, O11, O18, O32, O35, O98 and O101, were also identified. Thus, FC F42 was confirmed as an additional factor of virulence in the pathogenesis of porcine colibacillosis.

• Escherichia coli F42 piglets fimbriae diarrhea PCR.

Abstract in Portuguese:

Penatti M.P.A., Silva A.S., Valadares G.F. & Leite D.S. 2005. Occurrence of F42 colonization factor in Escherichia coli strains isolated from piglets with diarrhea. Pesquisa Veterinária Brasileira 25(1):31-33. Depto Microbiologia e Imunologia, Instituto de Biologia, Unicamp, Campinas, SP 13081-970, Brazil. E-mail: domingos@unicamp.br The objective of this study was to determine the presence of the colonization factor F42 in 168 strains of Escherichia coli isolated from diarrheic stools of newborn piglets. The presence of F42 in 12 (7.1%) strains was detected with the agglutination test. Through the Polymerase Chain Reaction (PCR) of F42 positive strains, gene encoding enterotoxins (ST-I, ST-II, LT-I and LT-II) were detected. The finding of ST-I/ST-II genes in 50% of the strains, ST-I (16%) and ST-II (25%) indicates a strong association of FC F42 with heat-stable enterotoxins (91%). In contrast, the thermolabile enterotoxin (LT-I and LT-II) genes were not detected. Serogroups of F42 positive strains were determined, serogroup O8 being the most prevalent (41,7%). Other serogroups, as there are O9, O11, O18, O32, O35, O98 and O101, were also identified. Thus, FC F42 was confirmed as an additional factor of virulence in the pathogenesis of porcine colibacillosis.

Abstract in English:

Assis R.A., Lobato F.C.F., Serakides R., Santos R.L., Dias G.R.C., Nascimento R.A.P., Abreu V.L.V, Parreiras P.M. & Uzal F.A. 2005. Immunohistochemical detection of Clostridia species in paraffin-embedded tissues of experimentally inoculated guinea pigs. Pesquisa Veterinária Brasileira 25(1):4-8. Departamento de Medicina Veterinária Preventiva, Escola de Veterinária, Universidade Federal de Minas Gerais, Av. Presidente Antônio Carlos 6627, Cx. Postal 567, Belo Horizonte, MG 30123-970, Brazil. E-mail: assisra@rwnet.com.br Blackleg is caused by Clostridium chauvoei, whereas malignant oedema is caused by C. chauvoei, C. septicum, C. sordellii, C. perfringens type A, and/or C. novyi type A. Anti-C. chauvoei, anti-C. septicum, anti-C. sordellii and anti-C. novyi type A polyclonal antibodies were produced in rabbits and purified in a column of DEAE-cellulose. Aliquots of the antisera were conjugated with fluorescein isothiocyanate and the remaining was used for the streptavidin biotin peroxidase technique (SBPT). SBPT was standardized to detect C. chauvoei, C. septicum, C. sordellii and C. novyi type A in formalin-fixed, paraffin-embedded tissues of guinea pigs. SBPT was compared to a fluorescent antibody technique (FAT). Sections and smears of muscle from inoculation area (MIA), heart, liver, spleen and kidney, were obtained for both SBPT and FAT. Cross-reactions between the different Clostridial species were not observed. C. chauvoei and C. septicum were detected in all specimens from the animals inoculated with these microorganisms, while only sections of muscle obtained from all the animals inoculated with C. sordellii and C. novyi type A were positive. The same results observed by the SBPT, were obtained on tissue smears of these microorganisms stained by the FAT. The results indicate that SBPT is suitable for detection of C. chauvoei, C. septicum, C. sordellii and C. novyi type A in formalin-fixed, paraffin-embedded tissues of guinea pigs.

• Blackleg malignant oedema Clostridia guinea pigs fluorescent antibody technique streptavidin biotin peroxidase technique.

Abstract in Portuguese:

Assis R.A., Lobato F.C.F., Serakides R., Santos R.L., Dias G.R.C., Nascimento R.A.P., Abreu V.L.V, Parreiras P.M. & Uzal F.A. 2005. Immunohistochemical detection of Clostridia species in paraffin-embedded tissues of experimentally inoculated guinea pigs. Pesquisa Veterinária Brasileira 25(1):4-8. Departamento de Medicina Veterinária Preventiva, Escola de Veterinária, Universidade Federal de Minas Gerais, Av. Presidente Antônio Carlos 6627, Cx. Postal 567, Belo Horizonte, MG 30123-970, Brazil. E-mail: assisra@rwnet.com.br Blackleg is caused by Clostridium chauvoei, whereas malignant oedema is caused by C. chauvoei, C. septicum, C. sordellii, C. perfringens type A, and/or C. novyi type A. Anti-C. chauvoei, anti-C. septicum, anti-C. sordellii and anti-C. novyi type A polyclonal antibodies were produced in rabbits and purified in a column of DEAE-cellulose. Aliquots of the antisera were conjugated with fluorescein isothiocyanate and the remaining was used for the streptavidin biotin peroxidase technique (SBPT). SBPT was standardized to detect C. chauvoei, C. septicum, C. sordellii and C. novyi type A in formalin-fixed, paraffin-embedded tissues of guinea pigs. SBPT was compared to a fluorescent antibody technique (FAT). Sections and smears of muscle from inoculation area (MIA), heart, liver, spleen and kidney, were obtained for both SBPT and FAT. Cross-reactions between the different Clostridial species were not observed. C. chauvoei and C. septicum were detected in all specimens from the animals inoculated with these microorganisms, while only sections of muscle obtained from all the animals inoculated with C. sordellii and C. novyi type A were positive. The same results observed by the SBPT, were obtained on tissue smears of these microorganisms stained by the FAT. The results indicate that SBPT is suitable for detection of C. chauvoei, C. septicum, C. sordellii and C. novyi type A in formalin-fixed, paraffin-embedded tissues of guinea pigs.

Abstract in English:

Portiansky E.L., Quiroga M.A., Machuca M.A. & Perfumo C.J. 2004. Mycoplasma suis in naturally infected pigs: an ultrastructural and morphometric study. Pesquisa Veterinária Brasileira 24(1):1-5. Instituto de Patología, Faculdad de Ciencias Veterinarias, Universidad Nacional de La Plata, Calle 60 y 118, C.C. 296, (1900) La Plata, Buenos Aires, Argentina. E-mail: elporti@fcv.unlp.edu.ar Swine eperythrozoonosis is a haemotrophic disease caused by Eperythrozoon suis, actually called Mycoplasma suis, an extracellular bacterial organism that apparently adheres to pig erythrocyte membrane, inducing its deformation and damage. Since little is known about the ultrastructural and morphometrical aspects of this microorganism, the present work aimed to deal with these issues. The ultrastructural study revealed the presence of structures corresponding to tubules disseminated throughout the soma of M. suis. A variable separation between the microorganism membrane and that of the erythrocyte was also observed. The structural and positional attitude of M. suis could allow speculation about its mechanism of action.

• Eperythrozoonosis Mycoplasma suis ultrastructure morphometry pathogenesis.

Abstract in Portuguese:

Portiansky E.L., Quiroga M.A., Machuca M.A. & Perfumo C.J. 2004. Mycoplasma suis in naturally infected pigs: an ultrastructural and morphometric study. Pesquisa Veterinária Brasileira 24(1):1-5. Instituto de Patología, Faculdad de Ciencias Veterinarias, Universidad Nacional de La Plata, Calle 60 y 118, C.C. 296, (1900) La Plata, Buenos Aires, Argentina. E-mail: elporti@fcv.unlp.edu.ar Swine eperythrozoonosis is a haemotrophic disease caused by Eperythrozoon suis, actually called Mycoplasma suis, an extracellular bacterial organism that apparently adheres to pig erythrocyte membrane, inducing its deformation and damage. Since little is known about the ultrastructural and morphometrical aspects of this microorganism, the present work aimed to deal with these issues. The ultrastructural study revealed the presence of structures corresponding to tubules disseminated throughout the soma of M. suis. A variable separation between the microorganism membrane and that of the erythrocyte was also observed. The structural and positional attitude of M. suis could allow speculation about its mechanism of action.