Detection of virulence genes in environmental strains of Vibrio cholerae from estuaries in northeastern Brazil.

The objectives of this study were to detect the presence of Vibrio cholerae in tropical estuaries (Northeastern Brazil) and to search for virulence factors in the environmental isolates. Water and sediment samples were inoculated onto a vibrio-selective medium (TCBS), and colonies with morphological resemblance to V. cholerae were isolated. The cultures were identified phenotypically using a dichotomous key based on biochemical characteristics. The total DNA extracted was amplified by PCR to detect ompW and by multiplex PCR to detect the virulence genes ctx, tcp, zot and rfbO1. The results of the phenotypic and genotypic identification were compared. Nine strains of V. cholerae were identified phenotypically, five of which were confirmed by detection of the species-specific gene ompW. The dichotomous key was efficient at differentiating environmental strains of V. cholerae. Strains of V. cholerae were found in all four estuaries, but none possessed virulence genes.

DETECTION OF VIRULENCE GENES IN ENVIRONMENTAL STRAINS OF Vibrio cholerae FROM ESTUARIES IN NORTHEASTERN BRAZIL / Detecção de genes de virulência em estirpes de Vibrio cholerae isolados de estuários no Nordeste do Brasil

The objectives of this study were to detect the presence of Vibrio cholerae in tropical estuaries (Northeastern Brazil) and to search for virulence factors in the environmental isolates. Water and sediment samples were inoculated onto a vibrio-selective medium (TCBS), and colonies with morphological resemblance to V. cholerae were isolated. The cultures were identified phenotypically using a dichotomous key based on biochemical characteristics. The total DNA extracted was amplified by PCR to detect ompW and by multiplex PCR to detect the virulence genes ctx, tcp, zot and rfbO1. The results of the phenotypic and genotypic identification were compared. Nine strains of V. cholerae were identified phenotypically, five of which were confirmed by detection of the species-specific gene ompW. The dichotomous key was efficient at differentiating environmental strains of V. cholerae. Strains of V. cholerae were found in all four estuaries, but none possessed virulence genes.

O objetivo deste estudo foi detectar a presença potencial virulência de Vibrio cholerae isolado de estuários do Nordeste do Brasil. Amostras de água e sedimento foram coletadas e inoculadas sobre meio seletivo para víbrios (TCBS) e colônias com características morfológicas de V. cholerae foram isoladas. A identificação fenotípica seguiu chave dicotômica baseada em caraterísticas bioquímicas. Foram empregadas as técnicas de amplificação da polimerase em cadeia (PCR) utilizando o gene ompW e a de multiplex PCR para detecção de genes de virulência (ctx, tcp, zot e rfbO1). Os resultados da identificação das diferentes abordagens foram comparados. Nove cepas de V. cholerae foram identificadas fenotipicamente e cinco confirmadas através da detecção do gene ompW. A chave dicotômica utilizada foi eficiente para a confirmação da espécie. Os quatro estuários analisados apresentaram estirpes de V. cholerae, e nenhuma das cepas isoladas apresentaram genes de virulência.

Molecular characterization of Aeromonas spp. and Vibrio cholerae O1 isolated during a diarrhea outbreak / Caracterização molecular de Aeromonas spp. e Vibrio cholerae O1 isolados durante um surto de diarréia

This work aimed to assess pathogenic potential and clonal relatedness of Aeromonas sp. and Vibrio cholerae isolates recovered during a diarrhea outbreak in Brazil. Clinical and environmental isolates were investigated for the presence of known pathogenic genes and clonal relatedness was assessed by intergenic spacer region (ISR) 16S-23S amplification. Four Aeromonas genes (lip, exu, gcat, flaA/B) were found at high overall frequency in both clinical and environmental isolates although the lip gene was specifically absent from selected species. A fifth gene, aerA, was rarely found in A. caviae, the most abundant species. The ISR profile revealed high heterogeneity among the Aeromonas isolates and no correlation with species identification. In contrast, in all the V. cholerae isolates the four genes investigated (ctxA, tcpA, zot and ace) were amplified and revealed homogeneous ISR and RAPD profiles. Although Aeromonas isolates were the major enteric pathogen recovered, their ISR profiles are not compatible with a unique cause for the diarrhea events, while the clonal relationship clearly implicates V. cholerae in those cases from which it was isolated. These results reinforce the need for a better definition of the role of aeromonads in diarrhea and whether they benefit from co-infection with V. cholerae.

O objetivo deste trabalho foi estabelecer o potencial patogênico e a relação clonal de isolados de Aeromonas sp. e Vibrio cholerae obtidos durante um surto de diarréia. Isolados clínicos e ambientais foram investigados quanto à presença de genes de virulência e sua relação clonal foi obtida através de amplificação da Região Espaçadora Intergênica (REI) 16S-23S. Quatro genes de Aeromonas (lip, exu, gcat, flaA/B) foram encontrados em alta frequência embora o gene lip tenha se mostrado ausente em algumas espécies. Um quinto gene, aerA, foi raramente encontrado em A. caviae, a espécie mais abundante. O perfil da REI revelou alta heterogeneidade entre os isolados de Aeromonas e nenhuma correlação com espécie. Em contraste, todas as amostras de V. cholerae amplificaram os genes investigados (ctxA, tcpA, zot e ace) e revelaram perfil clonal através de REI e RAPD. Embora Aeromonas tenha sido o principal patógeno isolado, o perfil da REI não é compatível como única causa para os eventos de diarréia, enquanto a relação clonal de V. cholerae aponta esse microrganismo como o provável agente do surto. Estes resultados reforçam a necessidade de definir melhor o papel de Aeromonas em diarréias e de que forma essas bactérias se beneficiam quando em co-infecção com V. cholerae.

Molecular characterization of Aeromonas spp. and Vibrio cholerae O1 isolated during a diarrhea outbreak.

This work aimed to assess pathogenic potential and clonal relatedness of Aeromonas sp. and Vibrio cholerae isolates recovered during a diarrhea outbreak in Brazil. Clinical and environmental isolates were investigated for the presence of known pathogenic genes and clonal relatedness was assessed by intergenic spacer region (ISR) 16S-23S amplification. Four Aeromonas genes (lip, exu, gcat, flaA/B) were found at high overall frequency in both clinical and environmental isolates although the lip gene was specifically absent from selected species. A fifth gene, aerA, was rarely found in A. caviae, the most abundant species. The ISR profile revealed high heterogeneity among the Aeromonas isolates and no correlation with species identification. In contrast, in all the V. cholerae isolates the four genes investigated (ctxA, tcpA, zot and ace) were amplified and revealed homogeneous ISR and RAPD profiles. Although Aeromonas isolates were the major enteric pathogen recovered, their ISR profiles are not compatible with a unique cause for the diarrhea events, while the clonal relationship clearly implicates V. cholerae in those cases from which it was isolated. These results reinforce the need for a better definition of the role of aeromonads in diarrhea and whether they benefit from co-infection with V. cholerae.

Antibiotic resistance of Vibrio parahaemolyticus isolated from pond-reared Litopenaeus vannamei marketed in Natal, Brazil

Ten out of fifty fresh and refrigerated samples of shrimp (Litopenaeus vannamei) collected from retailers in Natal (Rio Grande do Norte, Northeastern Brazil) tested positive for Vibrio parahaemolyticus. The Kanagawa test and multiplex PCR assays were used to detect TDH and TRH hemolysins and the tdh, trh and tlh genes, respectively. All strains were Kanagawa-negative and tlh-positive. Antibiotic susceptibility testing was done for seven antibiotics by the agar diffusion technique. Five strains (50 percent) presented multiple antibiotic resistance to ampicillin (90 percent) and amikacin (60 percent), while two strains (20 percent) displayed intermediate-level resistance to amikacin. All strains were sensitive to chloramphenicol. Intermediate-level susceptibility and/or resistance to other antibiotics ranged from 10 to 90 percent, with emphasis on the observed growing intermediate-level resistance to ciprofloxacin. Half our isolates yielded a multiple antibiotic resistance index above 0.2 (range: 0.14-0.29), indicating a considerable risk of propagation of antibiotic resistance throughout the food chain.

Antibiotic resistance of Vibrio parahaemolyticus isolated from pond-reared Litopenaeus vannamei marketed in natal, brazil.

Ten out of fifty fresh and refrigerated samples of shrimp (Litopenaeus vannamei) collected from retailers in Natal (Rio Grande do Norte, Northeastern Brazil) tested positive for Vibrio parahaemolyticus. The Kanagawa test and multiplex PCR assays were used to detect TDH and TRH hemolysins and the tdh, trh and tlh genes, respectively. All strains were Kanagawa-negative and tlh-positive. Antibiotic susceptibility testing was done for seven antibiotics by the agar diffusion technique. Five strains (50%) presented multiple antibiotic resistance to ampicillin (90%) and amikacin (60%), while two strains (20%) displayed intermediate-level resistance to amikacin. All strains were sensitive to chloramphenicol. Intermediate-level susceptibility and/or resistance to other antibiotics ranged from 10 to 90%, with emphasis on the observed growing intermediate-level resistance to ciprofloxacin. Half our isolates yielded a multiple antibiotic resistance index above 0.2 (range: 0.14-0.29), indicating a considerable risk of propagation of antibiotic resistance throughout the food chain.

Raw oysters can be a risk for infections.

The aims of this study were to count and identify sucrose positive and negative vibrios isolated from cultivated Crassostrea rhizophorae oysters during their growing cycle. Every month for 12 months, 10 to 18 oysters were collected for study. Collections occurred at the Center for Studies of Coastal Aquaculture (CSCA), which is associated with the Institute of Marine Science, Labomar, located in Euzebio, Ceará, Brazil. Approximately 150 oysters and their intervalvular liquor were studied. Vibrio Standard Plates Counts (SPC) from oyster meat and their intervalvular liquor varied from 25 to 59,000,000 CFU/g. For most of the 12 months of the oysters' life, it was possible to identify Vibrio parahaemolyticus. Vibrio carchariae was identified in four collections. Among other isolated species, the most important, considering public health risks, was V. vulnificus, although only one strain was confirmed. We concluded that retail purchased oysters should never be eaten raw or undercooked because many species of the genus Vibrio are known to be pathogenic to humans and live naturally on and in shellfish throughout their life cycle.

Raw oysters can be a risk for infections

The aims of this study were to count and identify sucrose positive and negative vibrios isolated from cultivated Crassostrea rhizophorae oysters during their growing cycle. Every month for 12 months, 10 to 18 oysters were collected for study. Collections occurred at the Center for Studies of Coastal Aquaculture (CSCA), which is associated with the Institute of Marine Science, Labomar, located in Euzebio, Ceará, Brazil. Approximately 150 oysters and their intervalvular liquor were studied. Vibrio Standard Plates Counts (SPC) from oyster meat and their intervalvular liquor varied from 25 to 59,000,000 CFU/g. For most of the 12 months of the oysters' life, it was possible to identify Vibrio parahaemolyticus. Vibrio carchariae was identified in four collections. Among other isolated species, the most important, considering public health risks, was V. vulnificus, although only one strain was confirmed. We concluded that retail purchased oysters should never be eaten raw or undercooked because many species of the genus Vibrio are known to be pathogenic to humans and live naturally on and in shellfish throughout their life cycle.

[Characterization of Aeromonas spp isolates from newborns hospitalized]. / Caracterização de Aeromonas spp isoladas de neonatos hospitalizados.

Aeromonas spp is recognized as pathogenic to humans after consumption of contaminated water and food. In the present investigation, 2,323 rectal swab samples from newborns hospitalized in Rio de Janeiro were evaluated with a view to isolating Aeromonas. The samples were collected and sent to the national reference laboratory for cholera and other bacterial intestinal infections, at the Oswaldo Cruz Institute of the Oswaldo Cruz Foundation. The swabs were subjected to enrichment in alkaline peptonated water with the addition of 1% sodium chloride (NaCl) and alkaline peptonated water plus 3% NaCl (37 degrees C/18-24h) and were streaked onto agar that was selective for Pseudomonas-Aeromonas (GSP Agar). Fifty-six Aeromonas strains were isolated, distributed as follows: Aeromonas caviae (42.8%), Aeromonas media (25%), Aeromonas veronii biogroup sobria (10.7%), Aeromonas hydrophila (9%), Aeromonas veronii biogroup veronii (5.3%), Aeromonas sobria (1.8%), Aeromonas jandaei (1.8%), Aeromonas schubertii (1.8%) and Aeromonas sp (1.8%). Resistance to one or more antimicrobial drugs was observed in 26.8% of the strains. Considering the importance of Aeromonas, there is an urgent need to warn about this in relation to nosocomial infection control.

Caracterização de Aeromonas spp isoladas de neonatos hospitalizados / Characterization of Aeromonas spp isolates from newborns hospitalized

Aeromonas spp é reconhecida como patogênica para o homem após o consumo de água e alimentos contaminados. Na presente investigação, foram avaliadas 2.323 amostras de swabs retais de neonatos hospitalizados no Rio de Janeiro objetivando o isolamento de Aeromonas. As amostras foram coletadas e enviadas ao Laboratório de Referência Nacional de Cólera e outras enteroinfecções bacterianas, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz. Os swabs foram submetidos ao enriquecimento em água peptonada alcalina adicionada de 1 por cento de cloreto de sódio (NaCl) e água peptonada alcalina adicionada de 3 por cento de NaCl (37ºC/18-24h) e semeadas em agar seletivo para Pseudomonas aeromonas (Agar GSP). Foram isoladas 56 cepas de Aeromonas assim distribuídas: Aeromonas caviae (42,8 por cento), Aeromonas media (25 por cento), Aeromonas veronii biogrupo sobria (10,7 por cento), Aeromonas hydrophila (9 por cento), Aeromonas veronii biogrupo veronii (5,3 por cento), Aeromonas sobria (1,8 por cento), Aeromonas jandaei (1,8 por cento), Aeromonas schubertii (1,8 por cento) e Aeromonas sp (1,8 por cento). Foi observada resistência a uma ou mais drogas antimicrobianas em 26,8 por cento das cepas. Considerando a relevância de Aeromonas torna-se urgente alertar sobre sua importância para o controle de infecções hospitalares.

Aeromonas spp is recognized as pathogenic to humans after consumption of contaminated water and food. In the present investigation, 2,323 rectal swab samples from newborns hospitalized in Rio de Janeiro were evaluated with a view to isolating Aeromonas. The samples were collected and sent to the national reference laboratory for cholera and other bacterial intestinal infections, at the Oswaldo Cruz Institute of the Oswaldo Cruz Foundation. The swabs were subjected to enrichment in alkaline peptonated water with the addition of 1 percent sodium chloride (NaCl) and alkaline peptonated water plus 3 percent NaCl (37°C/18-24h) and were streaked onto agar that was selective for Pseudomonas-Aeromonas (GSP Agar). Fifty-six Aeromonas strains were isolated, distributed as follows: Aeromonas caviae (42.8 percent), Aeromonas media (25 percent), Aeromonas veronii biogroup sobria (10.7 percent), Aeromonas hydrophila (9 percent), Aeromonas veronii biogroup veronii (5.3 percent), Aeromonas sobria (1.8 percent), Aeromonas jandaei (1.8 percent), Aeromonas schubertii (1.8 percent) and Aeromonas sp (1.8 percent). Resistance to one or more antimicrobial drugs was observed in 26.8 percent of the strains. Considering the importance of Aeromonas, there is an urgent need to warn about this in relation to nosocomial infection control.

Vigilância ambiental para cólera na região metropolitana de Bélem, Pará, no período de 1999 a 2006 / Environmental surveillance of cholera in the metropolitan region of Belém, Pará, Brazil, 1999-2006

Como parte do programa de vigilância ambiental para cólera em Belém, foi analisado, entre os anos de 1999 a 2006, um total de 704 amostras de águas superficiais e efluentes de esgoto, e, destas, 34,8 por cento foram positivas para V. cholerae e 11,8 por cento o foram para V. mimicus. Não foi isolada nenhuma amostra de V. cholerae O1 ou O139 durante este período. Os resultados do estudo demonstraram que o V. cholerae sorogrupo O1 não está circulando nos ambientes avaliados em sua forma viável e cultivável pelos métodos convencionais de cultura, entretanto, sabe-se que o mesmo é capaz de se manter em ambientes aquáticos com características semelhantes às encontradas na região amazônica por períodos suficientes para sua disseminação. Sugere-se a manutenção da vigilância ativa para cólera, a inclusão de novas metodologias buscando o conhecimento acerca da ocorrência ambiental de Vibrio cholerae O1 na sua forma viável, porém não cultivável, e a pesquisa de fatores de virulência nos isolados já obtidos.

Vigilância ambiental para cólera na região metropolitana de Bélem, Pará, no período de 1999 a 2006 / Environmental surveillance of cholera in the metropolitan region of Belém, Pará, Brazil, 1999-2006

Como parte do programa de vigilância ambiental para cólera em Belém, foi analisado, entre os anos de 1999 a 2006, um total de 704 amostras de águas superficiais e efluentes de esgoto, e, destas, 34,8 por cento foram positivas para V. cholerae e 11,8 por cento o foram para V. mimicus. Não foi isolada nenhuma amostra de V. cholerae O1 ou O139 durante este período. Os resultados do estudo demonstraram que o V. cholerae sorogrupo O1 não está circulando nos ambientes avaliados em sua forma viável e cultivável pelos métodos convencionais de cultura, entretanto, sabe-se que o mesmo é capaz de se manter em ambientes aquáticos com características semelhantes às encontradas na região amazônica por períodos suficientes para sua disseminação. Sugere-se a manutenção da vigilância ativa para cólera, a inclusão de novas metodologias buscando o conhecimento acerca da ocorrência ambiental de Vibrio cholerae O1 na sua forma viável, porém não cultivável, e a pesquisa de fatores de virulência nos isolados já obtidos. (AU)

Distribution of virulence markers in clinical and environmental Vibrio cholerae non-O1/non-O139 strains isolated in Brazil from 1991 to 2000.

One hundred seventy nine Vibrio cholerae non-O1/non-O139 strains from clinical and different environmental sources isolated in Brazil from 1991 to 2000 were serogrouped and screened for the presence of four different virulence factors. The Random Amplification of Polymorphic DNA (RAPD) technique was used to evaluate the genetic relatedness among strains. Fifty-four different serogroups were identified and V. cholerae O26 was the most common (7.8%). PCR analysis for three genes (ctxA, zot, ace) located of the CTX genetic element and one gene (tcpA) located on the VPI pathogenicity island showed that 27 strains harbored one or more of these genes. Eight (4.5%) strains possessed the complete set of CTX element genes and all but one of these belonged to the O26 serogroup suggesting that V. cholerae O26 has the potential to be an epidemic strain. The RAPD profiles revealed a wide variability among strains and no genetic correlation was observed.

[Aeromonas associated with an acute diarrhea outbreak in São Bento do Una, Pernambuco]. / Envolvimento de Aeromonas em surto de doença diarréica aguda em São Bento do Una, Pernambuco.

An acute diarrhea outbreak, with 2170 cases, was described during January to July, 2004, in São Bento do Una, Pernambuco. 582 stools were examined and an enteric pathogen was recovered in 25% (145 patients). Aeromonas species were the most frequent (114-19.5%) and the main isolates were Aeromonas caviae (57-9.8%), Aeromonas veronii biovar sobria (23-3.9%), Aeromonas veronii biovar veronii (15-2.6%) and other species (19-3.2%). The other isolated enteropathogens were Vibrio cholerae O1-Ogawa toxigenic (18-3.1%), Salmonella spp (8-1.4%), Shigella spp (3-0.5%) and Vibrio cholerae non-O1/non-O139 (2-0.3%).

Envolvimento de Aeromonas em surto de doenca diarréica aguda em São Bento do Una, Pernambuco / Aeromonas associated with an acute diarrhea outbreak in São Bento do Una, Pernambuco

No primeiro semestre de 2004, ocorreu um surto de diarréia em São Bento do Una, Pernambuco, registrando-se 2.170 casos. Nas 582 coproculturas realizadas, 145 (25 por cento) revelaram um enteropatógeno bacteriano, destacando 114 casos (19,5 por cento) com a participacão de Aeromonas, representadas por Aeromonas caviae (57/9,8 por cento), Aeromonas veronii biovar sobria (23/3,9 por cento), Aeromonas veronii biovar veronii (15/2,6 por cento) e outras espécies (19/3,2 por cento). Nos 31 episódios restantes (5,3 por cento), foram detectados: V. cholerae O1 Ogawa toxigênico (18/3,1 por cento), Salmonella spp (8/1,4 por cento), Shigella spp (3/0,5 por cento) e Vibrio cholerae não O1/não O139 (2/0,3 por cento).

Distribution of virulence markers in clinical and environmental Vibrio cholerae non-O1/non-O139 strains isolated in Brazil from 1991 to 2000

Cento e setenta e nove amostras de V. cholerae não O1/não O139, isoladas de casos clínicos (139) e de meio ambiente (40), no período de 1991 a 2000 no Brasil, foram caracterizadas antigenicamente pelo National Institute of Health (Japão) e investigadas quanto ao seu potencial genético de virulência, representado pelos genes ctxA, zot, ace e tcpA. As análises fenotípicas revelaram extraordinária diversidade antigênica, com a ocorrência de 54 diferentes sorogrupos, com prevalência para O26 (7,8%). A técnica de PCR, empregada na detecção dos genes localizados no elemento genético CTX (ctxA, zot, ace) e na Ilha de Patogenicidade de Vibrio-VPI (tcpA), possibilitou a identificação de 27 cepas contendo qualquer um desses genes. O gene ctxA (codificador da sub-unidade A de CT), só foi evidenciado no sorogrupo O26, sendo também o único capaz de se apresentar com o cassete de virulência de forma intacta. Com base nos resultados obtidos deste estudo preliminar, admite-se a hipótese da potencialidade destas cepas, evoluir para raças epidêmicas.

Aspectos e fonotípicos e genotípos de Vibrio cholerae não 01/não 0139 isolados de processos de entéricos humanos e de ambiente / Fenotipic e genotipic aspects of Vibrio choleras not 01/not 0139 isolated of enteric human and environment process

Até 1992, somente o sorogrupo O1 do Vibrio cholerae, compreendendo os biótipos Clássico e EI Tor era considerado como o agente etiológico da cólera, doença diarréica caracterizada por grande perda de líquidos e eletrólitos. A partir de 1993, com a descoberta e a propagação epidêmica do sorogrupo O139, intensificaram-se ainda mais as pesquisas sobre os demais sorogrupos pertencentes à espécie e amplamente distribuídos em ambientes aquáticos. No Brasil, durante o período epidêmico e nos anos posteriores, quando a cólera manteve-se de forma endêmica em algumas regiões do país, foram analisadas pelo Centro de Referência Nacional de Cólera e Enteroinfecções Bacterianas - CRNCEB mais de 17.000 cepas de V. Cholerae. Assim, de 1991 a 2000 foram reconhecidas nesta coleção, 179 amostras de V cholerae não O1/não O139 isoladas através de coprocultivos de casos clínicos (139) e de meio ambiente (40), que possibilitaram os estudos sobre a sua distribuição no país, na caracterização fenotípica e no potencial genético de virulência, representado pelos genes ctxA, zot e ace. Os resultados obtidos indicaram que a nível fenotípico, a espécie V. cholerae, demostrou um comportamento homogêneo, embora constituída de extraordinária diversidade antigênica somática, representada por 54 diferentes sorogrupos, com prevalência para O26 (9,4 por cento), O10 (8,6 por cento) e O37 (7,9 por cento), sem nenhuma correlação quanto à fonte de origem ou local de isolamento. Na caracterização fenotípica dos fatores devirulência, a toxina CT não foi evidenciada, a atividade hemolítica foi revelada em 122 isolamentos (68,2 por cento) e a toxina NAG-ST esteve presente em 38 cepas (21,2 por cento). Os genes ctxA, zot e ace do elemento genético CTX, pesquisados pela técnica de PCR, foram detectadaos em 26 amostras (24 clínicas e 2 ambientais). Salienta-se que apenas o sorogrupo O26 foi capaz de evidenciar o cassete de virulência intacto. O gene tcpA, principal codificador de TCP,portadoras de um ou mais genes de virulência, e em um isolamento que não continha nenhum destes genes. Admite-se com base nos resultados obtidos, na esfera da genética molecular, aventar a hipótese da potencialidade de certas cepas de V. cholerae não O1/não O139 como verdadeiros patógenos para o homem.

Vibrio vulnificus as a health hazard for shrimp consumers

Over the last 30 years, a number of Vibrio species found in the aquatic environment have been indicated as cause of disease in human beings. Vibrio vulnificus is an emergent pathogen, an invasive and lethal marine bacterium related to wound infection and held accountable for gastroenteritis and primary septicemia. It occurs quite frequently in marine organisms, mainly in mollusks. This study aimed at isolating and identifying strains of V. vulnificus based upon the analysis of twenty samples of seabob shrimp, Xiphopenaeus kroyeri (Heller), purchased at the Mucuripe fish market (Fortaleza, Brazil). TCBS agar was used to isolate suspect strains. Seven of twenty-nine strains isolated from six different samples were confirmed as such by means of biochemical evidence and thus submitted to biological assays to determine their virulence. The susceptibility of the V. vulnificus strains to a number of antibiotics was tested. None of the V. vulnificus strains showed signs of virulence during a 24-hour observation period, possibly due to the shedding of the capsules by the cells. As to the results of the antimicrobial susceptibility tests, the seven above-mentioned V. vulnificus strains were found to be sensitive to nitrofurantoin (NT), ciprofloxacin (CIP), gentamicin (GN) and chloramphenicol (CO) and resistant to clindamycin (CI), penicillin (PN) and ampicillin (AP)