Colicin type 7 produced by majority of Shigella sonnei isolated from Thai patients with diarrhoea

Thirty one out of 153 strains of Shigella sonnei isolated from Thai patients with diarrhoea showed antibacterial activity against S. sonnei by agar well diffusion method. All of them harbor plasmids with the genetic determination of colicin type 7 (Js) gene but without colicin E and colicin U gene. The PCR product obtained from strain 35/44 was shown to be the gene for colicin type 7 lytic protein (cja). The partially purified bacteriocin (PPB) containing colicin type 7 of strain 35/44 was prepared and used for characterization. The antibacterial activity of PPB against a total of 17 selected Gram-positive and Gram-negative bacteria was tested. It was found that PPB of strain 35/44 was active against E. coli O157, S. sonnei and S. boydii. The sensitivity of PPB from this strain to proteinase K, trypsin and α-chymotrypsin suggests the proteinaceous nature of these antimicrobial substances. Therefore, this isolated bacterium can be regarded as bacteriocin producing bacteria. The bacteriocin produced by this isolated S. sonnei was heat stable as evidenced by its ability to maintain the activity at 80 °C for 60 min. In addition, it was stable within a wide range of pH (3-9). The molecular weight of colicin type 7 from isolated S. sonnei strain 35/44 analyzed by SDS-PAGE was 54.4 kDa composing of at least five subunits. It is to our knowledge; the first report of Thai patients with diarrhoea that S. sonnei isolated from them contained colicin type 7.

An engineered multidomain fungicidal peptide against plant fungal pathogens / 生理学报

Fungal pathogens represent major problems for human health and agriculture. As eukaryotic organisms, fungi share some important features with mammalian cells. Therefore, current anti-fungal antibiotics often can not distinguish between fungi and mammalian cells, resulting in serious side effects in mammalian cells. Accordingly, there is strong impetus to develop antifungal alternatives that are both safe and effective. The E1 family of colicin are channel-forming bacteriocins produced by Escherichia coli, which are bactericidal only to E. coli and related species. To target the channel-forming domain of colicin to fungal cell membrane, we engineered a sexual mating pheromone of Candida albicans, α-factor pheromone to colicin Ia. A peptide was constructed consisting of an α mating pheromone of C. albicans fused to the channel-forming domain of colicin Ia to create a new fusion protein, pheromonicin-CA (PMC-CA). Indirect immunolabeling showed that the PMC-CA bound to fungal cells and inhibited growth in the laboratory and field. In the field, the protective activity of pheromonicin against rice blast disease was significantly greater, on a molar basis, than that of triazoles, tricyclazole or isoprothiolane. These results suggest that fusion peptides may be of value as fungicidal agents under agricultural conditions.

Recombinant expression, purification and characterization of colicin S4 / 生物医学工程学杂志

Broad-spectrum of conventional antibiotics is one of the key factors that cause antibiotics-resistance of many bacteria. Bacteriocins are regarded as the next generation of antibiotics on account of their narrow-spectrum bactericidal activities. Many attentions have been paid to colicins because they are believed to be safe in regard to human body. In this paper, the genes encoding colicin S4 and its immunity protein were cloned into pQE30 to produce colicin S4 expression vector pQE30-Col S4. Colicin S4 was highly expressed as soluble form in gE colig M15 containing pQE30-Col S4. The yields ranged from 30 mg/L to 50 mg/L. The recombinant colicin S4 with an additional 6 His-tag at its N-terminus was found being similar to the natural colicin S4 in antibacterial activity. It only showed bactericidal activity against E. coli strains, thus makig it attractive to develop this protein as a novel antibiotic with narrow spectrum.

Epidemiological Prevalence of Avian Pathogenic Escherichia coli Differentiated by Multiplex PCR from Commercial Chickens and Hatchery in Korea

We examined 216 Escherichia coli (E. coli) isolated from chickens and environmental specimens from hatcheries between 2005 and 2006 in order to evaluate the epidemiological prevalence of avian pathogenic E. coli (APEC) in Korea tentatively by multiplex PCR. The multiplex PCR which was used as tentative criteria of APEC targets 8 virulence-associated genes; enteroaggregative toxin (astA), increased serum survival protein (iss), iron-repressible protein (irp2), P fimbriae (papC), aerobactin (iucD), temperature-sensitive hemagglutinin (tsh), vacuolating autotransporter toxin (vat), and colicin V plasmid operon (cva/cvi) genes. The number of detected genes could be used as a reliable index of their virulence. It was demonstrated that E. coli strains already typed as APEC always harbor 5 to 8 genes, but non-APEC strains harbor less than 4 genes. Assuming the criteria of APEC is a possession of more than 5 virulenceassociated genes, we discriminated 24 APEC strains among the 216 E. coli strains. Contamination rates of APEC in the field were 31.3% in layers, 14.0% in broilers, 2.7% in broiler breeders, and 0.0% in environmental specimens from hatcheries. The combinational tendency of APEC examined is a fundamental possession of astA, iss and iucD genes and addition of cva/cvi, tsh, vat, and irp2 genes which have a critical importance for virulent traits of APEC. Compared with intravenous chicken challenge or embryo lethality assay, multiplex PCR method could be useful to discriminate APEC rapidly for convenient diagnosis.

Virulence factors of uropathogenic Escherichia coli from a University Hospital in Ribeirão Preto, São Paulo, Brazil / Fatores de virulência de Escherichia coli uropatogênicas provenientes de um Hospital Universitário em Ribeirão Preto, São Paulo, Brasil

The aim of the study was to determine the occurrence of virulence genes expressing fimbriae, production of hemolysin, colicin and aerobactin among a hundred Escherichia coli isolates obtained from in-and outpatients of a tertiary-care teaching hospital, between July and August 2000, showing clinical and laboratory signs of urinary tract infection (UTI). The presence of genes (pap, afa, sfa) for fimbriae expression was assayed using specific primers in a polymerase chain reaction. Among the isolates studied, the prevalence of the virulence factors was 96.0 percent, 76.0 percent, 24.0 percent, for hemolysin, aerobactin and colicin, respectively; the prevalence of genes coding for fimbrial adhesive systems was 32.0 percent, 19.0 percent and 11.0 percent for pap, sfa and afa respectively. The strains isolated from the outpatients displayed a greater number of virulence factors compared to those from hospitalized subjects, emphasizing the difference between these two kinds of patients.

O objetivo do trabalho foi determinar a ocorrência de fatores de virulência, tais como, a expressão de fímbrias, produção de hemolisina, colicina e aerobactina em 100 cepas de Escherichia coli isoladas de pacientes ambulatoriais e hospitalizados de um hospital universitário de nível de atendimento terciário, entre os meses de julho e agosto de 2000, que apresentavam sinais clínicos e laboratoriais de infecção do trato urinário (ITU). Foram pesquisados os genes pap, afa e sfa responsáveis pela expressão de fímbrias através da técnica de PCR. A freqüência dos fatores de virulência entre as cepas estudadas foi de 96,0 por cento, 76,0 por cento e 24,0 por cento para hemolisina, aerobactina e colicina respectivamente, e a prevalência dos genes para os sistemas de adesinas fimbriais foi de 32,0 por cento, 19,0 por cento e 11,0 por cento para os genes pap, sfa e afa respectivamente. As cepas isoladas dos pacientes ambulatoriais exibiram um número maior de fatores de virulência quando comparadas com aquelas provenientes de indivíduos hospitalizados.

Chromobacterium violaceum genome: molecular mechanisms associated with pathogenicity

Chromobacterium violaceum is a versatile, Gram-negative beta-protebacterium that grows in a variety of ecosystems in tropical and subtropical areas, such as the water and borders of the Negro River, in the Amazon region of Brazil. Although it is a saprophyte and is generally considered non-pathogenic, sporadic cases of human infection have been described, mainly in young children and in immunodeficient individuals. Although rare, infections with C. violaceum are characterized by rapid dissemination and high mortality. With the complete genome sequence of C. violaceum now available, a detailed description of the molecular arsenal required for this bacterium's remarkable versatility has been revealed. Most importantly, a more detailed picture of its biotechnological properties, including the characteristic violacein pigment, has emerged. The complete genome sequence also enabled us to make a thorough examination of the repertoire of genes encoding probable virulence factors, which determine the potential for pathogenesis. We described a number of genes involved in infectious processes, such as host cell adhesion, [quot ]contact-dependent secretion[quot ] of factors that promote cell invasion, as well as other virulence factors, such as cytolytic proteins. We also described genes involved with the synthesis of lipopolysaccharides and proteoglycan, known to elicit the synthesis of pro-inflammatory cytokines and involved in the detoxification process, which may contribute to the evasion of the bacteria from the host immune response

Recent updated aspects of colicins of Enterobacteriaceae

The colicins are protein compounds produced by, and active against, Escherichia coli and others members of Enterobacteriaceae family. At least 34 different colicins have been described and found to share an interesting number of features. In the present review we focus on the major characteristics of colicins of gram-negative bacteria and explore their production and practical applications.The colicins are protein compounds produced by, and active against, Escherichia coli and others members of Enterobacteriaceae family. At least 34 different colicins have been described and found to share an interesting number of features. In the present review we focus on the major characteristics of colicins of gram-negative bacteria and explore their production and practical applications

Factores de virulencia de Escherichia coli aviar asociados a la colisepticemia en pollos de engorde / Avian Escherichia coli virulence factors associated with coli septicemia in broiler chickens

In order to detect phenotypic characteristics associated with pathogenicity, 25 strains of Escherichia coli, isolated from clinical cases of colisepticemia in broiler chickens, were examined to determine the following properties: colicinogenicity, colicin V production, type 1 fimbriae, hemolysin expression and motility. Colicinogenicity occurred in 72 of the strains, 56 of all strains produced colicin V, 84 were positive for type 1 fimbriae and 80 were positive for motility. None of the strains had hemolytic activity; however, all of them, expressed at least one of the other characteristics studied. These results suggest that the diversity of phenotypes detected partially explain the multifactorial nature of avian colisepticemia.

Frecuencia de colicina y hemolisinas en Escherichia coli aisladas de pacientes embarazadas con infección de vías urinarias, sintomática y asintomática / Colicin and hemolisins in Eschirichia coli isolated from pregnant patients with symptomatic and asymptomatic urinary tract infections

Se estudió la frecuencia de producción de colicinas en 137 cepas provenientes de pacientes embarazadas con infección de vías urinarias (IVU), sintomática y asintomática. La frecuencia observada de cepas de E.coli uropatógenas, colicinogénicas aisladas en el primer grupo fue de 72.96 por ciento (n=96) mientras que en el segundo fue de 29.26 por ciento (n=41). Entre las cepas aisladas del grupo de pacientes sintomáticas, las colicinas encontradas con más frecuencia fueron: colicina V (23.9 por ciento), A (18.75 por ciento) y E1 (17.7 por ciento) y entre las cepas aisladas de población con infección asintomática, se identificaron con más frecuencia: colicina A (9.75 por ciento), E1 (17.0 por ciento) y V (2.4 por ciento). La frecuencia más elevada de colicina V en cepas provenientes de población sintomática con respecto a las aisladas en el grupo de pacientes asintomáticas, fue estadísticamente significativa (p = 0.025). Analizando la frecuencia de colicinas E1 y A, no se encontraron diferencias estadísticamente significativas. Entre las 137 cepas de E. coli estudiadas, se encontró que 37 por ciento de las mismas producen hemolisinas, observándose que 83.3 por ciento (n=24) de las cepas productoras de colicina V fueron hemolíticas mientras que 34 por ciento (n = 58) de cepas productoras de otras colicinas fueron hemolíticas y 12.7 por ciento (n=55) de las cepas hemolíticas no son colicinogénicas. Analizando los diferentes grupos productores de colicinas y hemolisinas se observa que estos resultados fueron estadísticamente significativos (p > 0.005). Los resultados presentados en este trabajo, sugieren que la producción de colicina entre cepas de Escherichia coli es un factor importante de patogenicidad, así como la asociación de hemolisina y colicina V, que puede favorecer que la infección de vías urinarias producida, se presente en forma de una infección sintomática.

Resistência a drogas e produçäo de bacteriocinas em linhagens de Escherichia coli e Enterobacter isoladas de indivíduos hospitalizados / Drug resistance and colicin production by Escherichia coli and Enterobacter isolated from hospitalized humans

Escherichia coli e Enterobacter foram isolados de grupos de indivíduos hospitalizados (H), recém-hospitalizados (P), sendo estudados quanto ao perfil de resistência às drogas ampicilina, cefalotina, cloranfenicol, estreptomicina, tetraciclina, gentamicina, canamicina e ao bicloreto de mercúrio, por meio da técnica de diluiçäo em meio sólido, e quanto à produçäo de colicinas. A resistência aos antibióticos betalactâmicos foi maior nas amostras isoladas dos grupos de portadores näo-hospitalizados (P) (modelo ampicilina-cefalosporina), em especial para o gênero Enterobacter. Por outro lado, a freqüencia das amostras colicinogênicas descresceu no grupo H em comparaçäo com amostras colicinogênicas decresceu no grupo H em comparaçäo com as amostras do grupo P. É provável que, em ambientes seletivos pela presença de elevadas concentraçöes de antibióticos, as linhagens portadoras de fenótipos sejam selecionadas e a colicinogênese, deslocada ou substituída, sendo mantida em ambientes näo-seletivos, devido à competitividade as linhagens de uma mesma espécie

Colicinogenicity and enteropathogenicity of Escherichia coli associated with gastroenteritis in man.

Sixty strains of Escherichia coli, were isolated and identified from 94 samples of infantile diarrhoea and traveller's diarrhoea. Eleven strains were found to be colicinogenic and colicin 'H' was found to be predominant in conjunction with other colicins. Five strains were enteropathogenic of which 055 and one untypable strain were highly enteropathogenic. A positive correlation could be established between haemolytic character, dulcitol fermentation and the virulence of the strain involved.

Conocimiento y posibles aplicaciones del estudio de las colicinas / Knowledge and possible aplications of the study of colicins

Las colicinas son sustancias proteicas con actividad bactericida, producidas por miembros de la familia Enterobacteriaceae y que presentan un espectro de acción limitado únicamente a especies de la misma familia. El estudio de las colicinas data desde 1925, aunque su primera clasificación, basada en sus propiedades químicas, físicas y biológicas, fue la realizada en 1948 por Frédériq. Posteriormente, Davies y Reeves en 1975 las dividieron en dos grandes grupos: A y B, de acuerdo con los diferentes patrones de resistencia obtenidos para una serie de mutantes resistentes a cada una de las colicinas conocidas. Se demostró que las mutatantes de resistencia a colicinas del grupo A nunca son resistentes a colicinas del grupo B, y viceversa. Actualmente se han hecho avances notables en el conocimiento del modo de acción de las colicinas. En efecto, se ha determinado que las colicinas pueden actuar en tres formas diferentes: 1) aquellas que actúan específicamente en la membrana celular, induciendo canales dependientes de diferencias de voltaje; 2) las que presentan actividad endonucleolítica, y 3) el caso especial de la colicina M, que es capaz de inhibir específicamente la síntesis de mureína. En general, se ha determinado que el efecto bactericida de las colicinas en las células sensibles precisa de tres partes de la molécula: 1) la unión específica de la colicina con su receptor en la membrana celular externa, que requiere de la parte central de la proteína; 2) la parte -NH2 terminal de la colicina, la cual es necesaria para que ésta atraviese la membrana celular, y 3) la parte -COOH terminal, que es indispensable para el reconocimiento de la colicina con su blanco específico. Las colicinas están codificadas en plásmidos; se han localizado varios de los genes involucrados tanto en la producción de la colicina, como de la proteína de liberación, así como de la proteína que le confiere inmunidad a la célula portadora de dicho plásmido. Los genes estructurales que codifican para dichas proteínas están bajo el control del regulón SOS, que se encuentra reprimido por la proteína LexA. El conocimiento de los plásmido colicinogénicos (factores col+) ha facilitado el desarrollo de la biotecnología, debido a que son multicopia y autorreplicables, por lo que son empleados como vectores de clonación en diferentes estudios del DNA. No obstante el uso más frecuente del conocimiento del fenómeno de colicinogenia en diferentes partes del mundo, ha sido en estudios epidemiológicos Así, se ha establecido que la frecuencia de cepas colicinogénicas es mayor entre los aislados de individuos enfermos, en comparación con los obtenidos de individuos sanos de la misma especie y de la misma ubicación geográfica. Por su parte, la colicina V ha sido ampliamente reconocida como un marcador de patogenicidad entre cepas de Escherichia coli, mientras que la colicina E1 se ha identificado frecuentemente entre sujetos sanos. Por otro lado, a pesar de que las colicinas se han detectado desde hace más de setenta y cinco años, aún no se conocen los efectos biológicos que puedan tener sobre el hospedero humano portador de cepas colinogénicas. Consecuentemente, para establecer si las colicinas pueden conferir alguna ventaja no sólo a las cepas productoras, sino también al hospedero, se requieren aún numerosos trabajos de investigación biomédica

The diameter of water pores formed by colicin la in planar lipid bilayers

The effective size of colicin Ia channel was tested by a recently described method 9FEMS, Microbiology and Immunology (1992). 105: 93-100) in which the nonelectrolyte molecules with different hydrodynamic diameters (0.52 to 5.0nm) were used as molecular tools. We have shown that despite low conductance (55-105 pS at 1.5 MKCl, pH 7.0) the ion channels formed by colicin Ia have a fairly large water pore diameter equal to 1.66-1 1.88nm. The results are discussed in terms of an energetic barrier for ions passing into the channel lumen

Transferable colicinogeny in Salmonella bareilly.

Twenty eight (5.6%) of the 500 isolates of S. bareilly studied were found to be colicin producers. Of these 27 (96.4%) were Col V producers. None of these produced aerobactin and 18 (64.3%) were multidrug resistant. Among 23 (85.2%) strains both drug resistance as well as colicinogeny could be transferred by conjugation. This is the first time that the transferable colicinogeny has been demonstrated in S. bareilly.

Plasmid composition of Shigella flexneri and Shigela sonnei strains isolated from diarrhoeic and asymptomatic children in northeastern Brazil

Nove amostras de S. flexneri e seis de S. sonnei foram isoladas de crianças assintomáticas (3 S.flexneri e 2 S. sonnei) e diarreicas em Recife. Todas as linhagens foram analisadas e comparadas quanto a invasibilidade (teste de Sereny), produçäo de colicinas, ligaçäo ao corante vermelho Congo e resistência a antibióticos. As amostras albergavam de dois a sete diferenças plasmídeos e a maioria deles apresentou peso molecular inferior a 6 MDal. As amostras de S. sonnei isoladas de portadores assintomáticos continham consideravelmente menos plasmídeos que as linhagens isoladas de pacientes diarréicos. A possível associaçäo entre plasmídeos e resistência a antibióticos, produçäo de colicina E1 e invasibilidade é discutida

Cloning of strutural genes for colicin V and their role in pathogenicity of invasive Escherichia coli

Os genes estruturais para colicina V do plasmídio pMV14 foram clonados no vetor pYP328. Estes genes foram isolados em um fragmento de ácido deoxiribonucleico de 2.4 kb o qual näo transportou ou näo expressou os genes de virulência da amostra UEL 14. A inserçäo do transposon Tn5 no plasmídio pMV14 levou a construçäo de um plasmídio mutante, o qual näo produziu colicina V, mas conferiu virulência para pintos de um dia. Destes resultados, nós concluímos que a atividade da colicina V näo é essencial para a virulência mediada pelo plasmídio Col V em E. coli de origem aviária

Virulence factors of Eschericha coli in urinary isolates

Escherichia coli strains isolated from 100 urine samples taken from patients with urinary tract infections (UTI) and from 20 normal fecal (NF) samples were examined for serum resistance, mannose-resistant hemagglutination of human erythrocytes (MRHA) and for production of aerobactin, hemolysis and colicin. Among the UTI E. coli strains, 79% produced aerobactin, 69% showed serum resistance, 44% produced MRHA, 32% were beta-hemolytic and 22% were colicinogenic. A greater proportion of UTI E. coli strains produced aerobactin, colicin V, beta-hemolysis and MRHA when compared to NF strains. Production of MR hemagglutins was significant correlated with that of aerobactin and hemolysin. These results suggest that the presence of aerobactin may be a significant etiological factor in UTI, and that the production of MR adhesins and of hemolysin also might contribute to the virulence of these strains

Plasmid coding for aerobactin production and drug resistance is involved in virulence of Escherichia coli avian strains

Strain of avian septicemic E. coli were examined for association among the determinants of drug resistance, the genes for aerobactin production and virulence. In conjugation experiments, a single plasmid (100 Md) from a strain of septicemic E. coli (UEL 29) transferred to E. coli K12 pathogenicity for 1-day old chicks plus resistance to streptomycin and the ability to produce aerobactin and colicin. Additional evidence for the association of R-plasmid and the production of aerobactin, colicin, resistance to sulfadiazine and pathogenicity was obtained by disassociation when all traits were lost simultaneously. These data provide additional evidence for the importance of the aerobactin system for the pathogenicity of avian E. coli

Escherichia coli colicinogênicas isoladas de material clínico humano: estudo de multirresistência a antimicrobianos / Colicinogenic Escherichia coli isolated from human clinical material: a study of multiresistance to antimicrobial agents

Foram estudadas 183 amostras de Escherichia coli com respeito à produçäo de colicina e à resistência das amostras a antimicrobianos. Trinta e duas amostras (17,5%) eram colicinogênicas, sendo predominantes os colicinótipos E1 e E3. Dos resultados obtidos, verificou-se que as amostras colicinogênicas E1 apresentaram multirresistência à KN - CO - TT - STX em maior incidência que as amostras colicinótipos E3. A multirresistência esteve mais presente em amostras isoladas de secreçöes diversas

Colicin production and serum resistance in pathogenic Escherichia coli strains isolated from humans in North East Brazil

Seis linhagens de Escherichia coli patogênicas, isoladas no Recife (Brazil), foram analisadas quanto a presença de fatores associados a virulência. Todas as linhagens foram resistentes a açäo lítica do complemento no soro humano, carreavam marcas de resistência a antibióticos e albergavam plasmídeos de pesos moleculares diversos. Um isolado, a linhagem E. coli 3116, mostrou-se capaz de sintetizar colicina V e hemolisisna. A linhagem E. coli 3116 continha um plasmídeo de 128 MD que codificava a produçäo de colicina V e hemolisina além de resistência a ntibióticos, como pode ser demonstrado por experimentos de conjugaçäo e cura do plasmídeo. Análises eletroforéticas de transconjugantes e derivados curados da linhagem 3116 mostraram que a resistência ao soro näo era uma característica codificada pelo plasmídeo. A origem genética distinta da produçäo de colicina V e a resistência ao soro säo discutidas