Antimicrobial susceptibility profile of enterotoxigenic and enteropathogenic Escherichia coli isolates obtained from fecal specimens of children with acute diarrhea / Perfil de suscetibilidade a drogas antimicrobianas de amostras de Escherichia coli enterotoxigênica e enteropatogênica isoladas de espécimes fecais de crianças com doença diarreica aguda

ABSTRACT Among the diseases which etiopathogenesis is associated with Escherichia coli, acute diarrhea stands out. Studies on the characterization of the antimicrobial susceptibility profile contribute to the selection of appropriate empirical antimicrobial therapy. In this study, the antimicrobial susceptibility profile of 98 enterotoxigenic E. coli (ETEC) and enteropathogenic E. coli (EPEC) strains isolated from fecal specimens of children with acute diarrhea was evaluated. The resistance rates to ampicillin, sulfamethoxazole/trimethoprim, amoxicillin/clavulanate, and nalidixic acid were high, ranging from 34.7% to 10.2%. The result of this research recommends the use of cefotaxime and ceftriaxone for the empirical treatment of children with acute diarrhea which the etiology suggested is ETEC or EPEC.

RESUMO Entre as doenças cuja etiopatogenia está associada à Escherichia coli, destaca-se a doença diarreica aguda. Estudos que visam à caracterização do perfil de suscetibilidade antimicrobiana contribuem para o delineamento de antibioticoterapia empírica eficaz. Neste estudo, foi avaliado o perfil de suscetibilidade a antimicrobianos de 98 amostras de E. coli enterotoxigênica (ETEC) e E. coli enteropatogênica (EPEC) isoladas de crianças com doença diarreica. As frequências de resistência a ampicilina, sulfametoxazol-trimetoprima, amoxicilina-clavulanato e ácido nalidíxico foram elevadas, variando entre 34,7% e 10,2%. Esta pesquisa recomenda o emprego de cefotaxima e ceftriaxona para o tratamento empírico de crianças com quadro de diarreia cuja etiologia sugerida seja ETEC ou EPEC.

Antagonistic activity expressed by Shigella sonnei: identification of a putative new bacteriocin.

Bacteriocins are antibacterial, proteinaceous substances that mediate microbial dynamics. Bacteriocin production is a highly disseminated property among all major lineages of bacteria, including Shigella. In this paper, we addressed the purification and characterisation of a bacteriocin produced by a Shigella sonnei strain (SS9) isolated from a child with acute diarrhoea. The substance was purified through ammonium-sulphate precipitation and sequential steps of chromatography. The intracellular fraction obtained at 75% ammonium sulphate maintained activity following exposure to pH values from 1-11 and storage at -80ºC for more than two years and was inactivated by high temperatures and proteases. The molecular mass of the purified bacteriocin was determined by mass spectrometry to be 18.56 kDa. The N-terminal sequence of the bacteriocin did not match any other antibacterial proteins described. A putative new bacteriocin produced by S. sonnei has been detected. This bacteriocin may represent a newly described protein or a previously described protein with a newly detected function. Considering that SS9 expresses antagonism against other diarrhoeagenic bacteria, the bacteriocin may contribute to S. sonnei virulence and is potentially applicable to either preventing or controlling diarrhoeal disease.

Antagonistic activity expressed by Shigella sonnei: identification of a putative new bacteriocin

Bacteriocins are antibacterial, proteinaceous substances that mediate microbial dynamics. Bacteriocin production is a highly disseminated property among all major lineages of bacteria, including Shigella. In this paper, we addressed the purification and characterisation of a bacteriocin produced by a Shigella sonnei strain (SS9) isolated from a child with acute diarrhoea. The substance was purified through ammonium-sulphate precipitation and sequential steps of chromatography. The intracellular fraction obtained at 75% ammonium sulphate maintained activity following exposure to pH values from 1-11 and storage at -80ºC for more than two years and was inactivated by high temperatures and proteases. The molecular mass of the purified bacteriocin was determined by mass spectrometry to be 18.56 kDa. The N-terminal sequence of the bacteriocin did not match any other antibacterial proteins described. A putative new bacteriocin produced by S. sonnei has been detected. This bacteriocin may represent a newly described protein or a previously described protein with a newly detected function. Considering that SS9 expresses antagonism against other diarrhoeagenic bacteria, the bacteriocin may contribute to S. sonnei virulence and is potentially applicable to either preventing or controlling diarrhoeal disease.