RESUMO
New variants of Vibrio cholerae O1 have appeared in different time-frames in various endemic regions, especially in Asia and Africa. Sixty-nine strains of V. cholerae O1 isolated in Zambia between 1996 and 2004 were investigated by various genotypic techniques to determine the lineage of virulence signatures and clonality. All strains were positive for Vibrio seventh pandemic Islands (VSP)-I and VSP-II and repeat toxin (RTX) gene clusters attesting their El Tor lineage. Interestingly, strains isolated in recent times (2003-2004) were identified as an altered variant (El Tor biotype that harbours El Tor type rstR but produce classical ctxB) that replaced completely the progenitor El Tor strains prevalent in 1996-1997. Recent altered variant strains differed from prototype El Tor strains isolated earlier in that these strains lacked two ORFs, VC0493 and VC0498, in the VSP-II region. PFGE analysis revealed two major clonal lineages in the strains; cluster A represented the strains isolated before 2003 and cluster B the altered strains isolated in 2003-2004. Cluster A was closely related to prototype El Tor reference strain isolated in Bangladesh in 1971. Cluster B was found to be matched with Bangladeshi altered strains but was different from the hybrid strains isolated from Mozambique and Bangladesh. This report provides important information on the genesis of altered strains of V. cholerae O1 isolated in Zambia and emphasizes the need for further studies to follow the trends of evolutionary changes.
Assuntos
Cólera/microbiologia , DNA Bacteriano/genética , Tipagem Molecular , Vibrio cholerae O1/classificação , Vibrio cholerae O1/genética , Toxina da Cólera/genética , Análise por Conglomerados , Eletroforese em Gel de Campo Pulsado , Evolução Molecular , Ilhas Genômicas , Genótipo , Humanos , Família Multigênica , Fases de Leitura Aberta , Vibrio cholerae O1/isolamento & purificação , ZâmbiaRESUMO
Vibrio cholerae O1 isolates collected during cholera outbreaks occurring from late 2007 to early 2008 in northern Vietnam were revealed to represent an altered strain containing the RS1 element followed by a CTX prophage harboring El Tor type rstR and classical ctxB on the large chromosome.
Assuntos
Toxina da Cólera/biossíntese , Cólera/epidemiologia , Cólera/microbiologia , Surtos de Doenças , Vibrio cholerae O1/isolamento & purificação , Técnicas de Tipagem Bacteriana , Toxina da Cólera/genética , Impressões Digitais de DNA , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Viral/química , DNA Viral/genética , Ordem dos Genes , Genótipo , Humanos , Dados de Sequência Molecular , Prófagos/genética , Análise de Sequência de DNA , Sintenia , Vibrio cholerae O1/classificação , Vibrio cholerae O1/genética , Vietnã/epidemiologiaRESUMO
BACKGROUND: New-generation, orally administered cholera vaccines offer the promise of improved control of cholera in sub-Saharan Africa. However, the high prevalence of human immunodeficiency virus (HIV) infection in many cholera-affected African populations has raised doubts about the level of protection possible with vaccination. We evaluated a mass immunization program with recombinant cholera-toxin B subunit, killed whole-cell (rBS-WC) oral cholera vaccine in Beira, Mozambique, a city where the seroprevalence of HIV is 20 to 30 percent. METHODS: From December 2003 to January 2004, we undertook mass immunization of nonpregnant persons at least two years of age, using a two-dose regimen of rBS-WC vaccine in Esturro, Beira (population 21,818). We then assessed vaccine protection in a case-control study during an outbreak of El Tor Ogawa cholera in Beira between January and May 2004. To estimate the level of vaccine protection, antecedent rates of vaccination were compared between persons with culture-confirmed cholera severe enough to have prompted them to seek treatment and age- and sex-matched neighborhood controls without treated diarrhea. RESULTS: We assessed the effectiveness of the vaccine in 43 persons with cholera and 172 controls. Receipt of one or more doses of rBS-WC vaccine was associated with 78 percent protection (95 percent confidence interval, 39 to 92 percent; P=0.004). The vaccine was equally effective in children younger than five years of age and in older persons. A concurrently conducted case-control study designed to detect bias compared persons with treated, noncholeraic diarrhea and controls without diarrhea in the same population and found no protection associated with receipt of the rBS-WC vaccine. CONCLUSIONS: The rBS-WC vaccine was highly effective against clinically significant cholera in an urban sub-Saharan African population with a high prevalence of HIV infection.
Assuntos
Vacinas contra Cólera , Cólera/prevenção & controle , Programas de Imunização , Adolescente , Adulto , Estudos de Casos e Controles , Criança , Pré-Escolar , Cólera/epidemiologia , Toxina da Cólera , Diarreia/epidemiologia , Diarreia/virologia , Estudos de Viabilidade , Feminino , Infecções por HIV/complicações , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Moçambique/epidemiologia , Fragmentos de Peptídeos , Vigilância da População , Resultado do Tratamento , Vacinas de Produtos Inativados , Vibrio cholerae/isolamento & purificaçãoRESUMO
OBJECTIVE: As residents of sub-Saharan Africa are at high risk for HIV and cholera, it is biologically plausible that immune suppression caused by HIV infection predisposes to cholera. Our aim was to assess the potential association between both diseases. METHODS: We conducted a case-control study in Beira, Mozambique, a high-risk area for HIV and cholera. Between 1 January 2005 and 30 June 2006, experienced counsellors invited 132 suspected cholera cases and 528 age- and sex-matched controls to an HIV counselling and testing centre. RESULTS: Forty (30%) of the invited cases and 127 (24%) of the invited controls came for HIV testing. No significant differences in demographic and socio-economic baseline characteristics were detected between participants and non-participants. Twenty five of 167 (15%) individuals who underwent testing were found HIV-positive. The probability of a positive HIV-test was highest in participants between 40 and 49 years; 6 of 14 (43%) tested HIV-positive. Nine of 40 (23%) cholera cases were found to be HIV-infected compared with 16 of 127 (13%) controls (adjusted odds ratio 2.6; 95% CI 0.9-7.5; P = 0.08). DISCUSSION: The findings suggest that in a cholera-endemic area, HIV infection is associated with an increased risk for cholera. More research in HIV endemic settings is needed to confirm the findings and to explore the effect of HIV-related immunosuppression on the transmission of cholera.
Assuntos
Cólera/epidemiologia , Infecções por HIV/epidemiologia , Adolescente , Adulto , Estudos de Casos e Controles , Criança , Pré-Escolar , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Moçambique/epidemiologia , Fatores de Risco , Vibrio cholerae/isolamento & purificaçãoRESUMO
The genetic characteristics of Vibrio parahaemolyticus strains isolated in 2004 and 2005 in Mozambique were assessed in this study to determine whether the pandemic clone of V. parahaemolyticus O3 : K6 and O4 : K68 serotypes has spread to Mozambique. Fifty-eight V. parahaemolyticus strains isolated from hospitalized diarrhoea patients in Beira, Mozambique, were serotyped for O : K antigens and genotyped for toxR, tdh and trh genes. A group-specific PCR, a PCR that detects the presence of ORF8 of the filamentous phage f237, arbitrarily primed PCR, PFGE and multilocus sequence typing were performed to determine the pandemic status of the strains and their ancestry. All strains of serovars O3 : K6 (n=38) and O4 : K68 (n=4) were identified as a pandemic clonal group by these analyses. These strains are closely related to the pandemic reference strains of O3 : K6 and O4 : K68, which emerged in Asia in 1996 and were later found globally. The pandemic serotypes O3 : K6 and O4 : K68 including reference strains grouped into a single cluster indicating emergence from a common ancestor. The O3 : K58 (n=8), O4 : K13 (n=6), O3 : KUT (n=1) and O8 : K41 (n=1) strains showed unique characteristics different from the pandemic clone.
Assuntos
Diarreia/epidemiologia , Surtos de Doenças , Vibrioses/epidemiologia , Vibrio parahaemolyticus , Alelos , Proteínas de Bactérias/genética , Diarreia/microbiologia , Eletroforese em Gel de Campo Pulsado , Genótipo , Humanos , Dados de Sequência Molecular , Moçambique/epidemiologia , Fases de Leitura Aberta , Reação em Cadeia da Polimerase , Análise de Sequência de DNA , Sorotipagem , Vibrioses/microbiologia , Vibrio parahaemolyticus/classificação , Vibrio parahaemolyticus/genética , Vibrio parahaemolyticus/isolamento & purificaçãoRESUMO
A total of 99 isolates out of 370 colonization factor (CF)-positive, well-characterized enterotoxigenic Escherichia coli (ETEC) strains belonging to 13 different CF types isolated from diarrhoeal patients admitted to the hospital of the International Centre for Diarrhoeal Disease Research, Bangladesh, were tested. The isolates were selected at random based on expression of the major CFs prevailing in Dhaka, Bangladesh, from 1996 to 1998. These isolates were characterized by O-antigenic serotyping, randomly amplified polymorphic DNA (RAPD) analysis and biochemical fingerprinting using the PhenePlate (PhP) system. The 99 ETEC isolates belonged to 10 O serogroups, the predominant ones being O6 (n=28), O115 (n=20) and O128 (n=20). Most isolates of serogroup O6 (CS1+CS3, 11/14; CS2+CS3, 5/8) belonged to the same PhP/RAPD type (H/f), whereas other isolates of serogroup O6 (n=12) belonged to different PhP/RAPD types (Si/f and F/c). Eleven serogroup O128 (CFA/I) isolates belonged to the same PhP/RAPD type (E/b), whereas the other O128 isolates formed different PhP/RAPD types. Fifteen (75%) serogroup O115 isolates (together with fourteen isolates from serogroups O25, O114, O142 and O159) demonstrated two closely related common groups by PhP typing (A and A1) and belonged to the same PhP/RAPD type (A/a). Three major clonal groups were identified among the ETEC strains in this study, largely based on O-antigenic type, CF expression pattern and toxin profile.
Assuntos
Diarreia/microbiologia , Infecções por Escherichia coli/microbiologia , Escherichia coli/classificação , Escherichia coli/isolamento & purificação , Toxinas Bacterianas/biossíntese , Técnicas de Tipagem Bacteriana , Bangladesh/epidemiologia , Análise por Conglomerados , Impressões Digitais de DNA , DNA Bacteriano/genética , Diarreia/epidemiologia , Enterotoxinas/biossíntese , Escherichia coli/genética , Escherichia coli/fisiologia , Infecções por Escherichia coli/epidemiologia , Proteínas de Escherichia coli/análise , Proteínas de Escherichia coli/biossíntese , Proteínas de Fímbrias/análise , Hospitais , Humanos , Epidemiologia Molecular , Antígenos O/análise , Técnica de Amplificação ao Acaso de DNA Polimórfico , SorotipagemRESUMO
The Matlab variants of Vibrio cholerae O1, defined as hybrids between the classical and El Tor biotypes, were first isolated from hospitalized patients with acute secretory diarrhoea in Matlab, a rural area of Bangladesh. These variants could not be categorized as classical or El Tor biotypes by phenotypic and genotypic tests, and had representative traits of both the biotypes. A number of virulence-associated genes and/or gene clusters were screened by PCR and DNA sequencing. El Tor-specific gene clusters, Vibrio seventh-pandemic islands (VSP)-I and -II and repeat toxin (RTX) were present in the genome of these variants, indicating their El Tor lineage, whereas the nucleotide-sequence-derived CtxB amino acid sequence of these strains grouped them under the classical biotype. Matlab variants possessed all the necessary genes to initiate pandemics. The genetic relatedness of Matlab variants to the V. cholerae strains recently isolated in Mozambique is another important observation of this study, which underscores the epidemiological significance of Matlab variants.
Assuntos
Cólera/microbiologia , Vibrio cholerae O1/genética , Testes de Aglutinação , Sequência de Aminoácidos , Técnicas de Tipagem Bacteriana , Sequência de Bases , Toxina da Cólera/química , Toxina da Cólera/genética , DNA Bacteriano/química , DNA Bacteriano/genética , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , Polimixina B/metabolismo , Alinhamento de Sequência , Fatores de Virulência/química , Fatores de Virulência/genéticaRESUMO
Vibrio cholerae O1 isolates belonging to the Ogawa serotype, El Tor biotype, harbouring the classical CTX prophage were first isolated in Mozambique in 2004. Multilocus sequence typing (MLST) analysis using nine genetic loci showed that the Mozambique isolates have the same sequence type (ST) as O1 El Tor N16961, a representative of the current seventh cholera pandemic. Analysis of the CTX prophage in the Mozambique isolates indicated that there is one type of rstR in these isolates: the classical CTX prophage. It was also found that the ctxB-rstR-rstA-rstB-phs-cep fragment was PCR-amplified from these isolates, which indicates the presence of a tandem repeat of the classical CTX prophage in the genome of the Mozambique isolates. The possible origin of these isolates and the presence of the tandem repeat of the classical prophage in them implicate the presence of the classical CTX phage.
Assuntos
Vibrio cholerae O1/classificação , Proteínas de Bactérias/genética , Bacteriófagos/genética , Variação Genética , Genoma Bacteriano/genética , Humanos , Dados de Sequência Molecular , Moçambique , Prófagos/genética , Proteínas Repressoras/genética , Análise de Sequência de DNA , Especificidade da Espécie , Sequências de Repetição em Tandem/genética , Vibrio cholerae O1/genéticaRESUMO
BACKGROUND: Early detection of cholera outbreaks is crucial for the implementation of the most appropriate control strategies. METHODS: The performance of an immunochromatographic dipstick test (Institute Pasteur, Paris, France) specific for Vibrio cholerae O1 was evaluated in a prospective study in Beira, Mozambique, during the 2004 cholera season (January-May). Fecal specimens were collected from 391 patients with acute watery nonbloody diarrhea and tested by dipstick and conventional culture. RESULTS: The overall sensitivity and specificity of the rapid test compared to culture were 95% (95% confidence interval [CI]: 91%-99%) and 89% (95% CI: 86%-93%), respectively. After stratification by type of sample (rectal swab/bulk stool) and severity of diarrhea, the sensitivity ranged between 85% and 98% and specificity between 77% and 97%. CONCLUSION: This one-step dipstick test performed well in the diagnosis of V. cholerae O1 in a setting with seasonal outbreaks where rapid tests are most urgently needed.
Assuntos
Cólera/diagnóstico , Testes Imunológicos/instrumentação , Testes Imunológicos/métodos , Adolescente , Adulto , Criança , Pré-Escolar , Fezes/microbiologia , Feminino , Humanos , Masculino , Moçambique , Risco , Sensibilidade e EspecificidadeRESUMO
In previous studies with strains of the Shigella dysenteriae provisional serovars E22383 and E23507 from diarrhoeal stools from patients in Bangladesh, two strains of Shigella species were identified as Shigella boydii provisional serovar E16553 by a reference laboratory. Further tests with an antiserum to an international type strain of the provisional serovar E16553 identified an additional 15 isolates. None of the isolates reacted with antisera to the established Shigella serovars or any other provisional serovars reported so far and all showed biochemical reactions typical of S. boydii. All of the isolates harboured the 140 MDa invasion plasmid, had the ipaH gene and produced keratoconjunctivitis in the guinea pig eye. All isolates were susceptible to ampicillin, sulfamethoxazole-trimethoprim, nalidixic acid, ciprofloxacin and mecillinam but eight strains were resistant to tetracycline. A single PFGE type (type A) was shown for all 17 clinical isolates, indicating a common source of origin. The pulsotype of the Bangladeshi isolates was closely related to that of a Japanese strain but was different from that of the type strain. On the basis of these biochemical, serological and virulence markers, and diverse geographical origin, it is recommended that the provisional status of serovar E16553 be changed and that it be included in the international serotyping classification scheme as S. boydii 19.
Assuntos
Disenteria Bacilar/microbiologia , Shigella boydii/classificação , Animais , Anti-Infecciosos/farmacologia , Bangladesh , Resistência Microbiana a Medicamentos , Fezes/microbiologia , Cobaias , Humanos , Ceratoconjuntivite/microbiologia , Shigella boydii/patogenicidade , Shigella boydii/fisiologia , Shigella dysenteriae/classificação , VirulênciaRESUMO
BACKGROUND: Dysentery accounts for 20% of the 4.6 million diarrhea-associated deaths among children in developing countries, with the risk from death in dysenteric persistent diarrhea 10-fold higher than that in acute dysentery. Although Shigella accounts for the majority of dysenteric episodes, very little is known about the epidemiology of postshigellosis persistent diarrhea. METHODS: Rural Bangladeshi children younger than 5 years of age (n = 1,756) were followed for 1 month after exposure to sentinel cases of Shigella dysentery. The likelihood of an acute diarrheal episode becoming persistent was assessed. RESULTS: Diarrhea caused by Shigella was significantly associated with an increased risk of persistent diarrhea (age-adjusted relative risk, 1.83; 95% confidence interval, 1.19 to 2.81). Despite the use of nalidixic acid in dysenteric episodes, persistent diarrhea occurred in 23% of children with shigellosis. Infection by multiply antibiotic-resistant Shigella isolates (age-adjusted relative risk, 3.76; 95% confidence interval, 1.51 to 9.36) and occurrence of shigellosis during infancy were observed to be risk factors for initiation of Shigella diarrhea persistence. However, 88% of the persistent shigellosis episodes occurred in older children, 50% were associated with nondysenteric shigellosis and 79% were caused by Shigella species other than Shigella dysenteriae 1. CONCLUSIONS: These data demonstrate the importance of Shigella as a cause of persistent diarrhea and indicate that strategies to prevent postshigellosis persistent diarrhea must be broad-based, with a focus on older children as well as infants, management of nondysenteric as well as dysenteric disease and prevention of diarrhea caused by multiple Shigella species.
Assuntos
Diarreia/epidemiologia , Diarreia/terapia , Disenteria Bacilar/complicações , Disenteria Bacilar/terapia , Bangladesh , Pré-Escolar , Estudos de Coortes , Fatores Epidemiológicos , Feminino , Hidratação , Humanos , Lactente , Masculino , Fatores de Risco , Vigilância de Evento SentinelaRESUMO
We investigated whether alternative clinical and microbiological criteria for outcome events affected estimates of vaccine efficacy in a randomized, double-blind field trial of B subunit-killed whole cell (BS-WC) and killed whole cell-only (WC) oral cholera vaccines among 62,285 rural Bangladeshi participants. At one year of follow-up estimates of vaccine protective efficacy (PE = 60%, P less than 0.0001 for BS-WC; PE = 54%, P less than 0.0001 for WC) against all treated diarrhoeal episodes associated with V. cholerae 01 were similar to estimates of efficacy against only those episodes which were clinically typical and unassociated with additional enteric pathogens (PE = 62%, P less than 0.0001 for BS-WC; PE = 52%, P less than 0.0001 for WC). In contrast, estimates of vaccine cross-protection against episodes associated with each of several agents antigenically related to V. cholerae 01 (LT-ETEC, non-cholera Vibrio sp, Aeromonas sp) were substantially reduced when mixed infections with V. cholerae 01 were excluded. We conclude that restrictive criteria intended to improve the specificity of the definition of cholera did not increase the detectability of vaccine efficacy against V. cholerae 01, but that exclusion of mixed infections with V. cholerae 01 was necessary to avoid false-positive conclusions about vaccine cross-protection against other potential target pathogens.
Assuntos
Vacinas contra Cólera/administração & dosagem , Cólera/prevenção & controle , Diarreia/prevenção & controle , Administração Oral , Adolescente , Bangladesh , Criança , Pré-Escolar , Diarreia/microbiologia , Fezes/microbiologia , Feminino , Humanos , Masculino , Avaliação de Processos e Resultados em Cuidados de Saúde , Vibrio cholerae/isolamento & purificaçãoRESUMO
We followed 1,756 young, rural Bangladeshi children less than five years of age for one month after identification of sentinel Shigella patients in their neighborhoods. Two hundred nineteen (12%) children developed Shigella diarrhea (shigellosis) and 227 (13%) developed culture-negative dysentery. Shigella flexneri (60%) and S. dysenteriae, type 1 (15%) were the most common isolates among shigellosis cases. Within individual neighborhoods, there was poor agreement (Kappa = 0.21) between Shigella species isolated from sentinel patients and from additional cases detected during surveillance. The risk of shigellosis increased substantially after infancy and peaked in the second year of life. Severe stunting, as assessed by height-for-age, was associated with an increased risk of shigellosis (adjusted odds ratio [ORa] = 1.67, 95% confidence interval [CI] = 1.09-2.57, P < 0.05), while breast-feeding was protectively associated (ORa = 0.40, 95% CI = 0.24-0.69, P < 0.001). Only 43% of the shigellosis cases reported bloody stools; frank dysentery occurred more frequently in S. dysenteriae 1 infections than in S. flexneri infections (ORa = 5.04, 95% CI = 1.76-14.48, P < 0.01), and was also associated with severe stunting (ORa = 2.16, 95% CI = 1.01-4.58, P < 0.05). Our findings show that the high risk of shigellosis in residentially exposed Bangladeshi children results from multiple Shigella strains circulating concurrently within the same neighborhood; demonstrate that the risk is notably modified by host age, nutritional status, and dietary patterns; and illustrate that the classic picture of dysentery is relatively infrequent and is correlated with the infecting species and with host nutritional status.
Assuntos
Disenteria Bacilar/epidemiologia , Adolescente , Adulto , Fatores Etários , Idoso , Bangladesh/epidemiologia , Criança , Pré-Escolar , Resistência Microbiana a Medicamentos , Disenteria Bacilar/transmissão , Humanos , Incidência , Lactente , Recém-Nascido , Modelos Logísticos , Estudos Longitudinais , Pessoa de Meia-Idade , Análise Multivariada , Prevalência , Fatores de Risco , População Rural , Shigella boydii/efeitos dos fármacos , Shigella boydii/isolamento & purificação , Shigella dysenteriae/efeitos dos fármacos , Shigella dysenteriae/isolamento & purificação , Shigella flexneri/efeitos dos fármacos , Shigella flexneri/isolamento & purificação , Shigella sonnei/efeitos dos fármacos , Shigella sonnei/isolamento & purificaçãoRESUMO
An indirect fluorescent antibody test for rapid detection of Shigella dysenteriae 1 in diarrheal stools was developed. A diagnosis could be made within 90 min of submission of specimens to the laboratory. On comparison with culture results, the test had a sensitivity of 92%, a specificity of 93%, and positive and negative predictive values of 94% and 92%, respectively.
Assuntos
Disenteria Bacilar/diagnóstico , Imunofluorescência , Shigella dysenteriae/isolamento & purificação , Criança , Pré-Escolar , Humanos , Lactente , Sensibilidade e EspecificidadeRESUMO
A spherical acid-fast organism measuring approximately 10 microns in diameter (Cyclospora sp.) has recently been implicated in diarrheal diseases in many parts of the world. We detected this organism in the stools of six Bangladeshi patients with diarrhea. Four patients had chronic diarrhea and two had acute diarrhea at the time of presentation. This is the first report of infection with this organism in the indigenous population from this region.
Assuntos
Coccidiose/parasitologia , Diarreia/parasitologia , Eucoccidiida/isolamento & purificação , Adulto , Animais , Bangladesh/epidemiologia , Criança , Pré-Escolar , Coccidiose/epidemiologia , Fezes/parasitologia , Feminino , Humanos , MasculinoRESUMO
Recent case-control studies in Bangladesh showed a high prevalence of enteropathogenic Escherichia coli (EPEC) strains (identified by DNA probes for virulence genes) associated with childhood diarrhoea. However, the clonal status of these strains is not known. A total of 94 EPEC isolates from 80 children with diarrhoea and 14 healthy matched controls isolated during 1991-1992 and 1993-1994 was characterised by serogrouping, enterobacterial repetitive intergenic consensus sequence PCR, and by a biochemical fingerprinting method (the phene plate or PhP system). Twelve O serogroups were found with O114 (n = 19) and O127 (n = 23) being the dominant serogroups. Most strains of O114 belonged to the same PhP/PCR types. Strains of O127 contained 16 that produced cytolethal distending toxin (CDT) and seven that did not; both were found among patients as well as controls. Results of PCR and PhP typing showed that CDT-positive strains belonged to the same clonal group and were related to one of the two PhP/PCR types of CDT-negative O127 strains. Thirty-one EPEC strains were O non-typable and 21 strains belonged to other less prevalent serogroups. These strains belonged to diverse PhP/PCR types and did not show any similarity to the strains of two major serogroups, O114 and O127. The results suggest that two clonal groups of EPEC strains are predominantly associated with childhood diarrhoea in Bangladesh.
Assuntos
Diarreia/microbiologia , Infecções por Escherichia coli/microbiologia , Escherichia coli/classificação , Escherichia coli/genética , Técnicas de Tipagem Bacteriana , Bangladesh , Estudos de Casos e Controles , Pré-Escolar , Impressões Digitais de DNA/métodos , DNA Bacteriano/análise , Diarreia/epidemiologia , Escherichia coli/isolamento & purificação , Infecções por Escherichia coli/epidemiologia , Humanos , Lactente , Recém-Nascido , Reação em Cadeia da Polimerase/métodos , Prevalência , SorotipagemRESUMO
Previous studies with three isolates from diarrhoeal stools suggested that Providencia alcalifaciens is an invasive enteric pathogen that also causes actin condensation in infected cells. These findings were extended in the present study with a further 14 diarrhoeal stool isolates of P. alcalifaciens and HEp-2 cell monolayers for invasion assays. Studies on invasion characteristics with two selected isolates suggested that P. alcalifaciens required prior growth at 37 degrees C for better invasion. Invasion and actin condensation were inhibited by an agent that inhibits microfilament formation, but not by agents that inhibit receptor-mediated endocytosis, microtubule formation, endosome acidification or receptor recycling. In time-course assays with HEp-2 cell monolayers maintained in medium containing gentamicin, P. alcalifaciens showed a small degree of multiplication after invasion of the cells, but viable bacteria could not be recovered over a 24-h period although the integrity of the cell monolayer was preserved during this period.
Assuntos
Diarreia/microbiologia , Infecções por Enterobacteriaceae/microbiologia , Providencia/fisiologia , Adolescente , Adulto , Cloreto de Amônio/farmacologia , Cadaverina/análogos & derivados , Cadaverina/farmacologia , Linhagem Celular , Criança , Pré-Escolar , Cloroquina/farmacologia , Colchicina/farmacologia , Citocalasina D/farmacologia , Diarreia Infantil/microbiologia , Feminino , Humanos , Imunossupressores/farmacologia , Lactente , Masculino , Pessoa de Meia-Idade , Providencia/efeitos dos fármacos , Providencia/crescimento & desenvolvimento , Temperatura , Fatores de TempoRESUMO
Three strains of Plesiomonas shigelloides isolated from patients with diarrhoea were agglutinated with Shigella flexneri 6 antiserum in slide and tube tests. All the strains were also agglutinated with a monoclonal antibody to the common group 1 antigen shared between S. flexneri serotypes and S. dysenteriae type 1. Further studies with one strain also showed sharing of antigenicity in an enzyme-linked immunosorbent assay. The results suggest that the strains share type-specific antigen with S. flexneri 6 and the common group 1 antigen with S. flexneri serotypes and S. dysenteriae 1. The sharing of antigens may have implications for cross-protection. One strain adhered to HEp-2 cell monolayers. None of the strains contained high mol. wt plasmids and there was no sequence homology with the invasiveness plasmid of Shigella spp. in DNA probe hybridisation. They were susceptible to the commonly used antibiotics. However, they possessed four other virulence-associated properties of Shigella spp. that included Congo-red binding, hydrophobicity, toxicity to HeLa cells and HEp-2 cell invasiveness (although they gave negative results in the Sereny test for invasiveness). These data suggest that the three unique strains might be considered pathogenic. Studies in animal models and human volunteers would be necessary to establish their pathogenic potential.
Assuntos
Antígenos de Bactérias/análise , Diarreia/microbiologia , Plesiomonas/patogenicidade , Shigella dysenteriae/patogenicidade , Shigella flexneri/patogenicidade , Testes de Aglutinação , Aderência Bacteriana , Linhagem Celular , Criança , Pré-Escolar , Reações Cruzadas , Citotoxinas/biossíntese , Disenteria Bacilar/microbiologia , Ensaio de Imunoadsorção Enzimática , Infecções por Bactérias Gram-Negativas/microbiologia , Humanos , Plesiomonas/imunologia , Shigella dysenteriae/imunologia , Shigella flexneri/imunologia , VirulênciaRESUMO
Seven strains of Hafnia alvei isolated from diarrhoeal stools of children resembled enteropathogenic Escherichia coli (EPEC) in that they produced attaching-effacing (AE) lesions in rabbit ileal loops and fluorescent actin staining in infected HEp-2 cells. In addition, a DNA probe from a chromosomal gene required by EPEC to produce AE lesions, hybridised to chromosomal DNA from all seven H. alvei strains. These findings indicate that there is a sharing of virulence-associated properties at the phenotypic and genetic levels by H. alvei and EPEC. H. alvei strains with these properties should be considered diarrhoeagenic.
Assuntos
Diarreia/microbiologia , Infecções por Enterobacteriaceae/microbiologia , Enterobacteriaceae/patogenicidade , Infecções por Escherichia coli/microbiologia , Escherichia coli/patogenicidade , Aderência Bacteriana , Southern Blotting , Criança , Enterobacteriaceae/genética , Escherichia coli/genética , Fezes/microbiologia , Células HeLa , Humanos , Íleo/microbiologia , Fenótipo , Plasmídeos , VirulênciaRESUMO
Of 200 isolates of Vibrio mimicus screened, one from water (N-57) agglutinated with V. cholerae O139 polyclonal antiserum (absorbed with a rough strain of V. cholerae only) and not with O139 polyclonal diagnostic antiserum (absorbed with the rough strain and V. cholerae O22 and O155). The antigenic relationship between V. cholerae 0139 and N-57 is of a,b-a,c type, where a is the common antigenic epitope and b and c are unique epitopes. Strain N-57 was assigned to a new serogroup of V. cholerae O194. It gave negative results in a monoclonal antibody-based rapid test and a PCR test specific for V. cholerae O139. It did not possess the ctx gene or produce cholera toxin. Antiserum to strain N-57 cross-protected infant mice against cholera on challenge with V. cholerae O139. Structural studies of the surface polysaccharides and studies of the rfb genes will shed more light on the extent of relatedness between V. mimicus N-57 and V. cholerae O139.