Effectiveness of aqueous and hydroalcoholic extracts of Acanthospermum australe (Loefl) Kuntze against diarrhea-inducing bacteria / Eficácia de extratos aquosos e hidroalcoólicos de Acanthospermum australe (Loefl) Kuntze contra bactérias indutoras de diarreia

Abstract Leaves and roots of Acanthospermum australe (Asteraceae) have been used in Brazilian folk medicine for the treatment of various ailments including diarrhea, skin diseases, blennorrhagia, dyspepsia, parasitic worms and malaria. The aim of study was to characterize the chemical profiles of the aqueous and hydroalcoholic extracts of leaves and roots of A. australe, and to evaluate their antimicrobial activities against diarrhea-inducing bacteria (Enterococcus faecalis, Shigella dysenteriae and Yersinia enterocolitica), as well as their cytotoxic properties. Aqueous leaf extracts were obtained by infusion, while aqueous root extracts were obtained by decoction. The hydroalcoholic leaf and root extracts were prepared by maceration in 90% ethanol for 3 days. Antimicrobial activity was assessed using standard techniques and cytotoxicity was evaluated using Chinese hamster ovary cells CHO-K1. Chemical analysis revealed the presence of tannins, flavonoids, saponins and phenolic compounds in the extracts. Although root extracts were not effective against E. faecalis, leaf extracts at concentrations of 20 mg/mL exhibited bactericidal activities against this microorganism. The hydroalcoholic root extract was unique in presenting a bactericidal effect against S. dysenteriae. None of the extracts showed bacteriostatic or bactericidal activities against Y. enterocolitica. The results presented herein demonstrate that the Gram-positive E. faecalis and the Gram-negative S. dysenteriae were susceptible to A. australe extracts, although bacteriostatic/bactericidal activities were only observed at concentrations considered too high for clinical application. Our results support the ethnopharmacological use of A. australe in the treatment of gastrointestinal disorders, particularly diarrhea caused by infectious bacteria, although further studies are required to determine the anti-diarrhea effects and the toxicities of the extracts in vivo.

Resumo Folhas e raízes de Acanthospermum australe (Asteraceae) têm sido usadas na medicina popular brasileira para o tratamento de várias doenças, incluindo diarreia, doenças de pele, blenorragia, dispepsia, vermes parasitas e malária. O objetivo deste estudo foi caracterizar os perfis químicos dos extratos aquosos e hidroalcoólicos das raízes e folhas de A. australe, e avaliar as suas atividades antimicrobianas contra as bactérias indutoras de diarreia (Enterococcus faecalis, Shigella dysenteriae e Yersinia enterocolitica), bem como sua citotoxicidade. Os extratos aquosos de folhas foram obtidos por infusão, enquanto que os extratos aquosos de raízes foram obtidos por decocção. Os extratos hidroalcoólicos de folhas e raízes foram preparados por maceração em etanol a 90% durante 3 dias. A atividade antimicrobiana foi avaliada utilizando técnicas padrão e a citotoxicidade foi avaliada utilizando células de ovário de hamster chinês CHO-K1. A análise química revelou a presença de taninos, flavonóides, saponinas e compostos fenólicos nos extratos. Apesar de extratos de raiz não foram eficazes contra E. faecalis, extratos de folhas em concentrações de 20 mg/mL apresentaram atividades bactericidas contra este microrganismo. O extrato hidroalcoólico de raiz foi o único a apresentar um efeito bactericida contra S. dysenteriae. Nenhum dos extratos apresentaram atividades bacteriostáticas ou bactericidas contra Y. enterocolitica. Os resultados apresentados demonstram que a bactéria Gram-positiva E. faecalis e a Gram-negativa S. dysenteriae foram suscetíveis aos extratos de A. australe, embora as atividades bacteriostáticos/bactericidas tenham sido apenas observados em concentrações consideradas elevadas para aplicação clínica. Os nossos resultados apoiam a utilização de etnofarmacológica de A. australe no tratamento de perturbações gastrointestinais, especialmente diarreia causadas por bactérias infecciosas, embora sejam necessários mais estudos para determinar os efeitos anti-diarreia e as toxicidades dos extratos in vivo.

[ study of sub-MIC ciprofloxacin effects on Shigella dysenteriae]

Shigella dysenteriae causes one of the most acute kinds of diarrhea which could be established as chronic infection with alternative periods of recurrence. Administration of normal doses of antibiotics will suppress microbial infections; however it is possible to control these infections by consumption of sub-MIC doses of certain antibiotics. In this basic study, a strain of Shigella dysenteriae [PTCC:1188] was used. After determination of MIC by microdilution method in Muller-Hinton Broth and MBC in Muller-Hinton Agar, the different dilutions [1/2,1/4,1/8] of MIC were prepared in order to study the sub-MIC effects of ciprofloxacin on some traits of Shigella dysenteriae. The results showed that different sub-MIC dilutions of ciprofloxacin could cause morphological changes in Shigella. The Shigella cells became filamentous in 1/2 MIC whereas this configuration was weaker in 1/4 MIC and 1/8 MIC. Meanwhile, the appearance of colonies was changed significantly due to the higher concentrations of sub-MIC. Some of the biochemical traits were affected by sub-inhibitory concentrations of ciprofloxacin. Ciprofloxacin is a drug of choice for shigellosis. According to the results of this study, treatment of Shigella infections would be possible by lower doses of ciprofloxacin

Re-emergence of multi-drug resistant Shigella dysenteriae with added resistance to ciprofloxacin in north India & their plasmid profiles.

BACKGROUND & OBJECTIVES: Multi drug resistant Shigellae pose a major threat in control of shigellosis with. Shigella dysenteriae being the most prevalent species at our centre before 1994. A gradual decrease in S. dysenteriae occurred over the years with a corresponding increase in S. flexneri which became the predominant serotype. From May to November 2003, an increase in number of patients admitted with clinical diagnosis of dysentery was noted in comparison to previous years, with a corresponding increase in the isolation of multi drug resistant S. dysenteriae. We report here the re-emergence of multi drug resistant S. dysenteriae at our tertiary care centre in north India after a gap of about 10 yr. Plasmid analysis of S. dysenteriae was also performed to study the origin and clonality of the isolates. METHODS: Stool samples were collected in Cary-Blair medium and processed by standard methods. Shigellae were confirmed by serotyping. Minimum inhibitory concentration was done by agar dilution method and E-test. Plasmid profiling of 18 isolates (16 S. dysenteriae 1 and 2 S. dysenteriae 2) was performed by modified alkali lysis method. Clinical details of patients were noted. RESULTS: A total of 64 patients with dysentery were admitted during the study period. Patients presented with unusually severe symptoms and six developed complications. Treatment failure with ciprofloxacin occurred in six patients who received cefotaxime and amikacin. There were 38 children below 5 yr of age. S. dysenteriae (18 isolates of S. dysenteriae 1 and 2 isolates of S. dysenteriae 2) were isolated from 20 of the 64 (31.2%) stool samples. S. dysenteriae re-emerged as the commonest isolate after a gap of nearly 10 yr. Fourteen of the 20 S. dysenteriae isolates were multi drug resistant; 12 were resistant to ciprofloxacin with MIC of 8-32 mug/ml. Plasmid profile analysis revealed that 6 of 11 ciprofloxacin resistant S. dysenteriae 1 had similar profiles. INTERPRETATION & CONCLUSION: Emergence of a clone of ciprofloxacin resistant S. dysenteriae 1 in north India is disturbing as treatment options in our geographic area are limited in view of already existing high drug resistance to nalidixic acid, co-trimoxazole and amoxycillin. A close monitoring of shifts in serogroup distribution and antibiotic resistance is required to guide clinicians for treatment of shigellosis.

Synergistic antimicrobial activity of tea & antibiotics.

Tea leaves are known for its antibacterial activity against many microorganisms. In this study we attempted to describe the synergistic antimicrobial activity of tea and antibiotics against enteropathogens. Antimicrobial activity of boiled water tea extract and organic solvent extract were studied against Salmonella typhimurium 1402/84, S. typhi, S. typhi Ty2a, Shigella dysenteriae, Yersinia enterocolitica C770, and Escherichia coli (EPEC P2 1265) determining minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and death rate kinetics at MBC of tea extract in presence of subinhibitory concentration of antibiotic. Both green tea or black tea extracts effectively inhibited the growth of S. typhimurium 1402/84, S. typhi, S. typhi Ty2a, S. dysenteriae, Y. enterocolitica C770, and E.coli (EPEC P2 1265). However, the growth inhibitory concentration of tea extract was lower for green tea as compared to black tea extract. Antimicrobial activity of green tea tea methanol: water extract tea was better as compared to boiled water tea extract of green tea. Based on death rate kinetics results, S.typhi Ty2a appeared to be highly sensitive and Y. enterocolitica C770 the most resistant. Chloramphenicol and tea extract in combination inhibited the growth of S.dysenteriae at 2.5 microg/ml chloramphenicol (MIC 5 microg/ml) and 5.094 mg/ml black tea extract (MIC 9.089 mg/ml). Tea extract showed synergistic activity with chloramphenicol and other antibiotics like gentamycin, methicillin and nalidixic acid against test strains.

Severe shigellosis in childhood.

A prospective study was performed on 20 bacteriologically proven pediatric cases of severe shigellosis admitted to the Department of Pediatrics, Chulalongkorn Hospital during March 1989 to March 1990. Fourteen patients were male and six were female. Shigella B was found in 85% and Shigella D in 15% of cases. The major indications for admission were convulsions and dehydration. Fifteen per cent of cases had underlying malignancies and 42.1% had malnutrition. Most patients had a peak of fever between 39.5 and 40.5 degrees C, serum sodium between 128-144 mEq/l. Mild acidosis was detected in 45% and moderate acidosis in 30% of cases. There were no statistical differences in peak of fever and serum sodium between patients who had convulsion and who did not. Shigellemia was found in one case who also had underlying neuroblastoma. One patient died due to necrotizing enterocolitis, septic shock and renal failure. Most of the organisms found resisted to ampicillin and trimethoprim-sulfamethoxazole (TMP-SMX). However, TMP-SMX was prescribed in most immunocompetent patients and they recovered well. All of three patients with underlying malignancy responded well to ceftriaxone.

Isolation of a fluoroquinolone resistant Shigella dysenteriae 1 strain from Calcutta.

Fourteen strains of Shigella spp. were isolated from patients aged 5-12 yr, hospitalized with dysentery during 1995-1996. The strains isolated were Shigella dysenteriae 1, S. flexneri and S.sonnei. All but one of the 14 strains were sensitive to ciprofloxacin and norfloxacin. The MIC of both the fluoroquinolones was 15 micrograms/ml for the resistant S.dysenteriae 1 strain (NRM4). Therefore, the careful use of antimicrobials is required for therapy of Shigellosis.

Changing antibiotic sensitivity patterns in shigellosis.

Over five and a half months stool cultures were performed in 154 patients admitted with suspected bacillary dysentery to the Professorial Paediatric Unit of the Teaching Hospital, Galle. Thirty one patients had a positive stool culture; Shigella dysenteriae type 1 was isolated in 23 patients, and S flexneri in 8. In both groups the antibiotic sensitivity pattern was uniform, the only difference being S dysenteriae type 1 being resistant to nalidixic acid while S flexneri was sensitive. This antibiotic sensitivity pattern was different to that reported from Colombo during the same period. Complications were observed in some patients with S flexneri infection.

Efficacy of aqueous extract of garlic & allicin in experimental shigellosis in rabbits.

The aqueous extract of garlic (Allium sativum) and allicin both showed significant in vitro antibacterial activity against isolates of multiple drug-resistant Shigella dysenteriae 1, Sh. flexneri Y, Sh. sonnei and enterotoxigenic Escherichia coli. The minimum inhibitory concentrations of the aqueous extract and allicin against Sh. flexneri Y were 5 and 0.4 microliters/ml, respectively. The two agents also showed promising in vivo antibacterial activity against Sh. flexneri Y when tested in the rabbit model of experimental shigellosis, fully curing the infected rabbits within 3 days. On the contrary, 4 of the 5 rabbits in the control group died within 48 h. The rectal swab of rabbits of the experimental groups became free of the challenge bacteria on the second day of treatment. The antibacterial activity against the challenge strain was observed in the sera of the treated rabbits with 30-60 min of administration of the agents. The LD50 values of the aqueous extract and allicin in mice were 173.78 ml/kg and 204.17 microliters/kg of body weight, respectively. At the therapeutic dose, the two agents did not show any adverse effects on the standard biochemical profile of blood.

Epidemias por salmonella y por shigella, importancia de la vigilancia epidemiologíca y control de la resistencia a los antibióticos / Epidemics by salmonella and shigella, importance of epidemiologic vigilance and control of the antibiotics resistence

El descubrimiento de los antibióticos y su aplicación clínica ha permitido el tratamiento y control de padecimientos infecciosos. Por otra parte, se ha descubierto que algunas enterobacterias desarrollan resistencia a las drogas antimocrobianas causada, principalmente por la presencia de elementos extracromosómicos denominados plasmidos. De entre estos microorganismos se han estudiado la salmonella y shigella con la finalidad de determinar las características de las mismas, los antibióticos a que se resisten y con cuales pueden ser tratados los padecimientos provocados por las mismas. La presencia de epidemias y las endemias en regiones de México así como en otras regiones del mundo, y consecuentemente el alto índice de morbilidad han inducido a los especialistas a investigar los procesos infecciosos provocados por shigella y la salmonella, se ha logrado establecer una clasificación de las mismas así como la sintomatología que producen las mismas. Para establecer un tratamiento determinado, se aisló al agente infeccioso, se le sometió a estudios para poder establecer a que drogas eran resistentes y a cuales no. De este modo se ha podido descrubir que algunos tipos de estas bacterias son resistentes, por ejemplo, al clorafenicol, la tetraciclina, la estreptomicina y a la ampicilina, en tanto que otras son suceptibles a los mismos, así mismo se ha observado que la región guarda cierta relación con el desarrollo de la resistencia