Abstract Yersinia enterocolitica is a widespread Gram-negative bacterium that causes gastrointestinal disease and other clinical manifestations in humans. Potentially pathogenic Y. enterocolitica has been isolated in Brazil, from human, environmental, food, and animal sources. Herein we report a genome sequence of Y. enterocolitica subsp. palearctica strain YE 19, serotype O:3, biotype 4, sequence type 18, with virulence determinants isolated from human blood in Rio de Janeiro in 2005. The results corroborate other findings that this strain harbors a set of virulence determinants that could play a role in host pathoadaptation and may also justify the successful dissemination of bioserotype 4/O:3 in Brazil. The presence of strains harboring all of these virulence genes in Brazil is a potential threat to young children and immunocompromised individuals, for whom yersiniosis are a significant source of morbidity and mortality. The results of a genomic data analysis will help understand the virulence of Brazilian strains and provide data for Y. enterocolitica studies worldwide.

ABSTRACT Detection of virulent strains associated with aquatic environment is a current concern for the management and control of human and animal health. Thus, Vibrio diversity was investigated in four estuaries from state of Ceará (Pacoti, Choró, Pirangi and Jaguaribe) followed by antimicrobial susceptibility to different antimicrobials used in aquaculture and detection of main virulence factors to human health. Isolation and identification were performed on TCBS agar (selective medium) and dichotomous key based on biochemical characteristics, respectively. Nineteen strains of genus Vibrio were catalogued. Vibrio parahaemolyticus (Choró River) and V. alginolyticus (Pacoti River) were the most abundant species in the four estuaries. All strains were submitted to disk diffusion technique (15 antimicrobials were tested). Resistance was found to: penicillin (82%), ampicillin (54%), cephalotin (7%), aztreonan (1%), gentamicin, cefotaxime and ceftriaxone (0.5%). Five pathogenic strains were chosen to verification of virulence factors. Four estuaries showed a high abundance of species. High number of tested positive strains for virulence is concerning, since some of those strains are associated to human diseases, while others are known pathogens of aquatic organisms.

ABSTRACT The herein presented assay provided a bacteriological and molecular characterization of 100 samples of L. monocytogenes isolated from human (43) and food (57) sources, from several regions of Brazil, and collected between 1975 and 2013. Antigenic characterization defined 49% of serotype 4b samples, followed by 28% of serotype 1/2b, 14% of serotype 1/2c, 8% of serotype 1/2a, and 1% of serotype 3b. Both type of samples from human and food origin express the same serotype distribution. Multiplex PCR analysis showed 13 strains of type 4b with the amplification profile 4b-VI (Variant I). Virulence genes hly, inlA, inlB, inlC, inlJ, actA, plcA, and prfA were detected in all samples, highlighting a deletion of 105pb on the actA gene in 23% of serotype 4b samples. Macrorestriction profile with ApaI at PFGE showed 55 pulsotypes, with the occurrence of the same pulsotype in hospitalized patients in São Paulo in 1992 and 1997, and two other highly related pulsotypes in patients hospitalized in Rio de Janeiro in 2008. Recognized pulsotypes in listeriosis cases have also been detected in food. Thus, the prevalence of a serotype and the persistence of certain pulsotypes herald future problems.

RESUMO: Este trabalho teve como objetivo realizar a detecção de cepas de Listeria monocytogenes de cortes cárneos bovinos bem como no ambiente de abatedouros frigoríficos localizados no Distrito Federal, promover a sorotipificação pela reação em cadeia da polimerase (PCR), realizar antibiograma e submeter às cepas à eletroforese de campo pulsado (Pulsed-field gel electrophoresis - PFGE). Foram analisados um total de 125 cortes cárneos bovinos, 45 amostras de swabs de carcaças e 43 amostras de swabs em que foram detectados 13 cepas de Listeria monocytogenes, sendo 11 em cortes cárneos bovinos e 2 swabs de ambiente em um abatedouro frigorifico. Não foram isoladas cepas de swabs de carcaça. Dentre as 13 cepas de Listeria monocytogenes foram encontradas seis cepas do sorotipo 4b, cinco do sorotipo 1/2c e duas cepas do sorotipo 1/2a. Dentre as 11 cepas de L. monocytogenes encontradas em cortes cárneos bovino, uma (9,1%) cepa apresentou resistência a eritromicina, outra (9,1%) cepa a gentamicina e outra a ciprofloxacina (9,1%) e todas as cepas (100%) apresentaram resistência ao Ác. Nalidíxico. Das duas (2) cepas oriundas de ralos de abatedouro frigorífico, todas (100%) apresentaram resistência ao Ác. Nalidíxico e a sulfonamidas. A análise por eletroforese de campo pulsante (PFGE) demonstrou 13 diferentes pulsotipos, em que foram agrupados em 3 diferentes grupos clonais, que coincidentemente se correlacionavam com os 3 diferentes sorotipos encontrados sugerindo uma ampla disseminação desses perfis no Distrito Federal.

ABSTRACT: The aim of the study was the analysis of Listeria monocytogenes strains in beef samples as well as slaughterhouse environment, located in the Federal District, promote serotyping by polymerase chain reaction (PCR), perform antibiotic susceptibility and submit the strains to Pulsed-field gel electrophoresis (PFGE). A total of 125 beef samples were analyzed, 45 samples of carcasses swabs and 43 swab samples. It detected 13 strains of Listeria monocytogenes, 11 in beef samples. and 2 in slaughterhouse environment. No carcass swabs strains were isolated. Among the 13 strains of L. monocytogenes six strains of serotype 4b were found, five serotype 1/2c and two strains of serotype 1/2a. Among the 11 strains of L. monocytogenes found in beef, one (9.1%) strain showed resistance to erythromycin, one (9.1%) strain to gentamicin, one to ciprofloxacin (9.1%) and all strains (100%) were resistant to nalidixic acid. The two strains coming from the slaughterhouse drains, all (100%) were resistant to nalidixic acid and Sulfonamides. The analysis by pulsed field gel electrophoresis (PFGE) showed 13 different pulsotypes; they were grouped into three different clonal groups, coincidentally correlated with the three different serotypes found, what suggests a widespread dissemination of these profiles in the Federal District, Brazil.

Abstract Although the consumption of fresh and minimally processed vegetables is considered healthy, outbreaks related to the contamination of these products are frequently reported. Among the food-borne pathogens that contaminate vegetables is Listeria monocytogenes, a ubiquitous organism that exhibits the ability to survive and multiply at refrigerated temperatures. This study aimed to evaluate the occurrence of L. monocytogenes in vegetables as well as the antimicrobial resistance of isolates. The results showed that 3.03% of samples were contaminated with L. monocytogenes, comprising 2.22% of raw vegetables and 5.56% of ready-to-eat vegetables. Multiplex PCR confirmed the virulence potential of the isolates. Antimicrobial resistance profiling showed that 50% of the isolates were susceptible to the antibiotics used. The resistance of one isolate to penicillin G, a commonly employed therapeutic agent, and the presence of serotype 4b, a serotype commonly associated with food-borne outbreaks, could be potential health hazards for consumers.

RESUMO Em 2004 ocorreu um surto de diarreia aguda no Estado de Pernambuco, Brasil. Setenta por cento (14 dos 20) dos sobrenadantes de cultura de Aeromonas caviae, isoladas neste episódio induziram acúmulo de líquido em testes de alça ligada de intestino de coelhos, assim como em teste em camundongos recém-nascidos. Os mesmos sobrenadantes mostraram também atividade citotóxica em células de Vero e Caco-2, mas não em células HeLa e HEp2. As atividades enterotóxicas e citotóxicas mantiveram-se mesmo após o aquecimento a 100 ºC dos sobrenadantes de cultura. Este trabalho revela a expressão de um provável fator diarreiogênico: uma enterotoxina-citotóxica termo-estável, produzida por A. caviae que pode ser associada ao surto de diarreia ocorrido no Brasil. Atualmente estamos purificando esta enterotoxina termo-estável, com o objetivo de elucidar seu papel como fator de virulência na diarreia causada por A. caviae.

SUMMARY In the present study enterotoxic and cytotoxic activities of twenty Aeromonas caviaestrains were examined. They originated from fecal specimens of patients with acute diarrhea during an outbreak in Brazil in 2004. Culture supernatants of fourteen strains (70%) caused fluid accumulation in rabbit ileal intestinal loops and in suckling mice assays, and also showed a cytotoxic activity in Vero and Caco-2 cells. The enterotoxic and cytotoxic factors were heat-stable after culture supernatants treatment at 100 ºC. The results revealed that A. caviaestrains produce a putative diarrheagenic virulence factor, a heat-stable cytotoxic enterotoxin that could be linked to the diarrhea outbreak that took place in Brazil.

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.

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.

Introduction The number of reports of intestinal infections caused by Aeromonas spp. has increased significantly in recent years. In most clinical laboratories, identification of these bacteria is carried out by general phenotypic tests that sometimes do not accurately differentiate Aeromonas and Vibrio. Methods A duplex-polymerase chain reaction (PCR) was developed directed to 2 targets identifying Aeromonas spp. pathogenic to humans. Results The duplex-PCR results were reproducible and specific for Aeromonas spp. pathogenic to humans. Conclusions This method will allow differentiation between Vibrio and Aeromonas spp. in patients with in cholera-like symptoms and can also be used in water quality monitoring.

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.

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.

Samples of sewage from a university hospital and a chemistry technical school were analysed for the percentage of bacterial tolerance to chromium (Cr), silver (Ag) and mercury (Hg). Additionally, we investigated the effect of these metals on pigmentation and on some enzymatic activities of the metal tolerant strains isolated, as well as antimicrobial resistance in some metal tolerant Enterobacteriaceae strains. Tolerance to Cr was observed mainly in Gram positive bacteria while in the case of Ag and Hg the tolerant bacteria were predominately Gram negative. Hg was the metal for which the percentage of tolerance was significantly higher, especially in samples from the hospital sewage (4.1%). Mercury also had the most discernible effect on color of the colonies. Considering the effect of metals on the respiratory enzymes, one strain of Ag-tolerantBacillus sp. and one of Hg-tolerant P. aeruginosa were unable to produce oxidase in the presence of Ag and Hg, respectively, while the expression of gelatinase was largely inhibited in various Gram negative strains (66% by Cr). Drug resistance in Hg-tolerant Enterobacteriaceae strains isolated from the university hospital sewage was greater than 80%, with prevalence of multiple resistance, while the Ag-tolerant strains from the same source showed about 34% of resistance, with the predominance of mono-resistance. Our results showed that, despite the ability of metal tolerant strains to survive and grow in the presence of these elements, the interactions with these metals may result in metabolic or phisiological changes in this group of bacteria.

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.

OBJECTIVE: To determine the prevalence of resistance to ampicillin, chloramphenicol, streptomycin, sulphonamides, and tetracyclines (ACSSuT) in Salmonella serovar Typhimurium definitive [phage] type (DT) 193 strains isolated from human sources over the last four decades. METHODS: From 2008 to 2010, 553 DT193 isolates out of 810 human-origin Salmonella ser. Typhimurium phage-typed strains isolated from the 1970s through 2008 were selected and tested for ACSSuT resistance: 91 strains isolated during the 1970s, 65 from the 1980s, 70 from the 1990s, and 327 from 2000-2008. Resistance profiles were determined using the disk diffusion method. RESULTS: †An antimicrobial susceptibility assay indicated 20.9%, or 116, of all isolates tested were ACSSuT-resistant, 52.0% (287) were resistant to one or more drugs in the ACSSuT profile, and 27.1% (150) were nonresistant (susceptible to antimicrobials). Based on the assay, overall antimicrobial resistance was extremely high in the 1970s (affecting 99.0% of isolates from that period) and remained high during the 1980s, when 95.4% of isolates had some type of antimicrobial resistance and incidence of Salmonella ser. Typhimurium DT193 R-type ACSSuT increased to 73.8%. R-type ACSSuT dropped to 27.1% (19 isolates) during the 1990s, and to 5.2% (17) during 2000-2008, despite a substantial increase in the number of isolates tested (397 versus 204, 111, and 98, respectively, for the previous three decades). CONCLUSIONS: †Although prevalence of Salmonella ser. Typhimurium DT193 R-type ACSSuT in Brazil has decreased since the 1970s, ACSSuT resistance markers continue to circulate. Therefore, continuous surveillance should be conducted to evaluate the occurrence of Salmonella ser. Typhimurium DT193 and its antimicrobial resistance.

OBJETIVO: Determinar la prevalencia de resistencia a la ampicilina, el cloranfenicol, la estreptomicina, las sulfonamidas y las tetraciclinas (ACSSuT) en cepas de Salmonella serovariedad Typhimurium fagotipo definitivo (DT) 193 aisladas de fuentes de origen humano durante las cuatro últimas décadas. MÉTODOS: Entre el 2008 y el 2010 se seleccionaron 553 aislados de DT193 entre 810 cepas de Salmonella serovariedad Typhimurium fagotipificadas aisladas desde la década de 1970 hasta el 2008, y en ellos se analizó la resistencia a ACSSuT: se estudiaron 91 cepas aisladas durante la década de 1970, 65 aisladas durante la década de 1980, 70 aisladas durante la década de 1990, y 327 aisladas entre el 2000 y el 2008, respectivamente. Los perfiles de resistencia a los antibióticos se determinaron mediante el método de difusión en disco. RESULTADOS: El antibiograma indicó que 20,9% (116) de todos los aislados que se analizaron fueron resistentes a ACSSuT, 52,0% (287) fueron resistentes a uno o más antibióticos del grupo ACSSuT y 27,1% (150) no fueron resistentes (es decir, fueron sensibles a dichos antibióticos). Según el análisis, la resistencia general a los antibióticos fue muy alta en la década de 1970 (y comprendió a 99,0% de los aislados de ese período) y continuó siendo alta durante la década de 1980, cuando 95,4% de los aislados presentó algún tipo de resistencia a los antibióticos y la incidencia de Salmonella serovariedad Typhimurium DT193 con resistencia de tipo ACSSuT aumentó hasta 73,8%. La resistencia de tipo ACSSuT descendió a 27,1% (31 aislados) durante la década de 1990, y a 5,2% (17 aislados) entre el 2000 y el 2008, a pesar del aumento importante en el número de aislados que se evaluaron (397 frente a 204, 111 y 98 en las tres décadas anteriores, respectivamente). CONCLUSIONES: Aunque la prevalencia de Salmonella serovariedad Typhimurium DT193 con resistencia de tipo ACSSuT en el Brasil ha disminuido desde la década de 1970, los marcadores de resistencia a ACSSuT continúan en circulación. Por consiguiente, debe llevarse a cabo una vigilancia permanente para evaluar la aparición de infecciones por Salmonella serovariedad Typhimurium DT193 y su resistencia a los antibióticos.

INTRODUÇÃO: Listeria monocytogenes é o agente etiológico da listeriose, doença de origem alimentar que acomete principalmente grávidas, pacientes imunodeprimidos e idosos. O tratamento primário é a associação de ampicilina a um aminoglicosídeo além de outros, em segunda escolha, representados por cloranfenicol, eritromicina, tetraciclina e rifampicina. O presente estudo teve como objetivo analisar o perfil de susceptibilidade aos antimicrobianos de amostras de origem humana isoladas nas últimas quatro décadas. MÉTODOS: Foram selecionadas 68 cepas provenientes de casos clínicos humanos ocorridos em diferentes regiões do país no período de 1970-2008. A susceptibilidade aos antimicrobianos testados foi determinada através dos critérios estabelecidos por Soussy pelo método de Kirby-Bauer e a concentração mínima inibitória realizada através do E-Test. RESULTADOS: A amostragem constituiu-se de 68 cepas, isoladas principalmente de líquido cefalorraquidiano, e hemocultura no período, pertencentes ao Laboratório de Zoonoses Bacterianas/LABZOO/Fiocruz. O sorovar L4b (60,3%) foi o mais prevalente, seguido do sorovar 1/2a (20,6%), 1/2b (13,2%) e aqueles mais raros representados por 1/2c, 3b e 4ab (5,9%). Todas as cepas foram sensíveis à ampicilina, cefalotina, eritromicina, gentamicina, teicoplanina e vancomicina. Apenas uma cepa (1,5%) apresentou resistência à rifampicina, enquanto duas (3%) foram resistentes à associação de sulfametoxazol-trimetoprim. CONCLUSÕES: Apesar de o estudo ter demonstrado uma baixa prevalência de amostras resistentes aos antimicrobianos indicados na terapêutica da listeriose humana, o sistema de monitoramento do perfil de resistência antimicrobiana é de extrema importância para a orientação do tratamento adequado, principalmente nas infecções em pacientes imunocomprometidos.

INTRODUCTION: Listeria monocytogenes is the causative agent of listeriosis, a foodborne illness that affects mainly pregnant women, the elderly and immunocompromised patients. The primary treatment is a combination of ampicillin with an aminoglycoside, in addition to a second-choice drug represented by chloramphenicol, erythromycin, tetracycline and rifampicin. The aim of this study was to analyze the antimicrobial susceptibility profile of strains isolated from human sources in the last four decades. METHODS: Sixty-eight strains were selected from the culture collection of the Laboratory of Bacterial Zoonoses/LABZOO/FIOCRUZ isolated in different regions of Brazil from 1970 to 2008 and primarily isolated from cerebrospinal fluid and blood culture. Susceptibility tests to antimicrobials drugs were evaluated using the criteria established by Soussy using the Kirby-Bauer method and E-Test strips were used to determine the minimum inhibitory concentration (MIC). RESULTS: Among the strains tested, serovar L4b (60.3%) was the most prevalent, followed by serovar 1/2a (20.6%), 1/2b (13.2%) and the more uncommon serovars 1/2c, 3b and 4ab (5.9%). All strains were susceptible to ampicillin, cephalothin, erythromycin, gentamicin, teicoplanin and vancomycin. Only one strain (1.5%) showed resistance to rifampin, and two (3%) were resistant to trimethoprim-sulfamethoxazole. MICs with values up to 2μg/ml reinforce the need for microbiological surveillance. CONCLUSIONS: The study demonstrated low prevalence of strains resistant to the antimicrobial drugs indicated in the treatment of human listeriosis. Monitoring antimicrobial resistance profile is still very important to determine adequate treatment, especially in immunocompromised patients.

The genus Listeria is composed of six species of which Listeria monocytogenes is considered the single pathogenic species that causes listeriosis in humans. Of the 13 serovars of L. monocytogenes, 1/2a, 1/2b and 4b are responsible for the majority of clinical cases. The aim of this work was to detect L. monocytogenes in the cerebrospinal fluid sample of premature newborns and to characterize this sample using biotyping, serotyping and molecular typing. The results indicated the presence of L. monocytogenesin the clinical sample studied. Moreover, the isolate was identified as the 4b serovar that was characterized by the presence of a unique 691 bp band after analysis using the Multiplex-PCR technique. The results of repeated Multiplex-PCR and sequencing have indicated that the L. monocytogenes isolate was an atypical 4b serovar, which is the first time this finding has been reported.

Verificou-se o nível de anticorpos vibriocidas em 41 indivíduos adultos, sem história passada ou presente de diarréia por Vibrio cholerae O1, residentes no município de São Bento do Una, Pernambuco. Nessa localidade ocorreu no início de 2004 um surto de diarréia, com múltiplos agentes bacterianos envolvidos, incluindo o vibrião colérico. Foi empregado o teste da microtitulação de anticorpos séricos vibriocidas, anti-Ogawa e anti-Inaba, considerando-se como indicativo de infecção por Vibrio cholerae O1, os títulos vibriocidas > 1:640. A freqüência dos reagentes foi de 36 (87,8%) para o sorovar Ogawa, o que evidencia a possível circulação do vibrião colérico, durante e/ou após a epidemia de diarréia.

The levels of vibriocidal antibodies were investigated among 41 adults without any past or present history of diarrhea due to Vibrio cholerae O1 who were living in the municipality of São Bento do Una, Pernambuco. A diarrhea outbreak occurred in this locality at the beginning of 2004, involving multiple bacterial agents, including Vibrio cholerae. The microtitration test was used to investigate the presence of anti-Ogawa and anti-Inaba vibriocidal serum antibodies. Vibriocidal titers e" 1:640 were considered indicative of infection by Vibrio cholerae O1. The frequency of the reagents was 36 (87.8%) for the Ogawa serovar, which showed that Vibrio cholerae O1 was possibly circulating during and/or after the diarrhea epidemic.