The antimicrobial activity of essential oils of oregano, thyme, basil, marjoram, lemongrass, ginger, and clove was investigated in vitro by agar dilution method and minimal inhibitory concentration (MIC) determination against Gram-positive (Staphylococcus aureus and Listeria monocytogenes) and Gram-negative strains (Escherichia coli and Salmonella Enteritidis). MIC 90% values were tested against bacterial strains inoculated experimentally in irradiated minced meat and against natural microbiota (aerobic or facultative, mesophilic, and psychrotrophic bacteria) found in minced meat samples. MIC 90% values ranged from 0.05%v=v (lemongrass oil) to 0.46%v=v (marjoram oil) to Gram-positive bacteria and from 0.10%v=v (clove oil) to 0.56%v=v (ginger oil) to Gramnegative strains. However, the MIC 90% assessed on minced meat inoculated experimentally with foodborne pathogen strains and against natural microbiota of meat did not show the same effectiveness, and 1.3 and 1.0 were the highest log CFU=g reduction values obtained against tested microorganisms.

The present study aimed at evaluating the in vitro antimicrobial activity of methanolic extracts of some medicinal plants against Escherichia coli, Salmonella Typhimurium, Staphylococcus aureus and Enterococcus sp. The methanolic extract of Caryophyllus aromaticus presented the highest anti-S. aureus activity and was effective against all bacterial strains tested. 3815-3744. E-mail: ary@ibb.unesp.br Further acquaintance with different ethnic groups has contributed to the development of research on natural products, to the increase in knowledge about the close relationship between the chemical structure of a certain compound and its biological properties, and to the understanding of the animal/ insect-plant interrelation (8). For these reasons, medicinal plants are important substances for the study of their traditional uses through the verification of pharmacological effects and can be natural composite sources that act as new anti-infectious agents.The present study aimed at evaluating the in vitro antimicrobial activity of plant (Allium sativum, Zingiber officinale, Caryophyllus aromaticus, Cymbopogon citratus, Mikania glomerata and Psidium guajava) extracts against Gram-positive and Gram-negative bacterial strains isolated from human infections. The determined plant parts (200g) were ground, extracted with 70% methanol and filtered after 48hs. The plant residue was re-extracted by adding 70% methanol and filtered again after 48hs. Such procedure was repeated every 72hs, completing three filtration processes. The filtrate was concentrated on a rotary evaporator at 45ºC for methanol elimination, and the extracts were kept in sterile bottles under refrigerated conditions until use. The dry weight of the extracts was obtained by allowing the solvent to evaporate and was used to determine concentration in mg/mL. (Methodology based on Betoni et al. (3); Table 1).Microbial susceptibility assays using the agar dilution (Mueller-Hinton Agar) method (%v/v and corresponding mg/ mL values) and the Minimal Inhibitory Concentration (MIC) were carried out for fifteen Salmonella Typhimurium, S. aureus, Enterococcus sp and E. coli strains plus one ATCC strain of each bacterium. Overnight cultures (37ºC) in Brain Heart

RESUMO:Estudos com plantas e utilização em terapias combinatórias têm sido estimulados. Verificou-se as possíveis interações entre óleos essenciais de plantas [canela (Cinnamomum zeylanicum Blume Lauraceae), capim-cidreira (Cymbopogon citratus (DC.) Stapf, Poaceae), hortelã-pimenta (Mentha piperita L. Lamiaceae), gengibre (Zingiber officinale Roscoe Zingiberaceae), cravo-da-índia (Caryophillus aromaticus L. Myrtaceae) e alecrim (Rosmarinus officinalis L. Lamiaceae)] combinados a oito drogas antimicrobianas frente a doze linhagens de Staphylococcus aureus e doze de Escherichia coli isoladas de humanos. Após determinação da Concentração Inibitória Mínima (CIM) para os óleos pelo método da diluição foram realizados ensaios para verificação de sinergismo entre os óleos essenciais e os antimicrobianos pela metodologia de Kirby & Bauer. S. aureus foi mais suscetível às interações óleos e drogas, tendo o óleo de capim cidreira apresentado sinergismo com as oito drogas testadas, seguido pelo óleo de hortelã com sete drogas. Nos ensaios com E. coli, houve sinergismo apenas para os óleos de alecrim (três drogas) e capimcidreira (duas drogas). Não ocorreram casos de antagonismo e os resultados de sinergismo foram influenciados pelos microrganismos estudados.Unitermos: Drogas antimicrobianas, bactérias, óleos essenciais, plantas medicinais, sinergismo.ABSTRACT: "Synergism between essential oils and antimicrobial drugs against Staphylooccus aureus and Escherichia coli strains from human infections". The studies with plants and combinatory therapy have been stimulated. The interactions between cinnamon (Cinnamomun zeylanicum Blume Lauraceae), lemon grass (Cymbopogon citratus (DC.) Stapf, Poaceae), mint (Mentha piperita L. Lamiaceae), ginger (Zingiber officinale Roscoe Zingiberaceae), clove (Caryophillus aromaticus L. Myrtaceae) and rosemary (Rosmarinus officinalis L. Lamiaceae) and eight antimicrobial drug was carried. It was made against twelve S. aureus and twelve E.coli strains isolated from human specimens. After minimal inhibitory concentration (MIC) values determination of essential oils by dilution agar method, the synergism assays were performed by Kirby and Bauer method. The S. aureus was susceptible to oils and drugs interactions, and the lemon grass oils showed synergism with all drugs tested followed by mint with seven drugs. E.coli assays, synergism was observed only with rosemary (three drugs) and lemon grass (two drugs). No antagonism between drugs and oils tested was observed and the results were variable according to microorganism used.

A ação antibacteriana in vitro de óleos essenciais de seis plantas foi verificada por meio da Concentração Inibitória Mínima (CIM=%v/v) pela diluição dos óleos em meio de cultura Mueller Hinton Agar, frente a linhagens de Staphylococcus aureus (n=16) e Escherichia coli (n=16) isoladas de casos clínicos humanos, além de 1 amostra padrão ATCC para cada espécie (Sa ATCC 25923 e Ec ATCC 25922), e determinação de curvas de sobrevivência em concentrações equivalentes a CIM90% dos respectivos óleos. O óleo essencial de canela foi o mais eficiente, com valores de CIM90% de 0,047 e 0,09 para S. aureus e E. coli respectivamente, enquanto gengibre (0,09), cravo da índia (0,095) e capim cidreira (0,1) apresentaram eficiências semelhantes para S. aureus. Frente a E. coli, os óleos de gengibre (0,52) e capim cidreira (0,55) foram equivalentes quanto à eficiência. De acordo com as curvas de sobrevivência, foi possível verificar também que os valores de CIM90% obtidos podem ser tanto bactericidas ou bacteriostáticas de acordo com a bactéria testada. Em conclusão, verificou-se que os óleos essenciais testados foram efetivos no controle do desenvolvimento bacteriano, sendo o potencial antimicrobiano diferente em função da espécie bacteriana testada, sendo que a bactéria Gram positiva (S. aureus) mostrou-se mais susceptível aos óleos testados que a Gram negativa (E. coli).

The biological properties of medicinal plants have been documented worldwide for many centuries. We aimed to evaluate interactions between crude extracts from Psidium guajava, Zingiber officinale, Cymbopogon citratus, Caryophyllus aromaticus, Mikania glomerata and Allium sativum samples and antimicrobial drugs against Escherichia coli strains. The susceptibility test performed was disc diffusion, and crude extracts were diluted (%v/v) into Müller-Hinton agar (MHA) at one quarter of the minimal inhibitory concentration for 90% (MIC(90%)) of E. coli strains found previously. Synergistic interactions were observed between C. citratus and polymyxin, and A. sativum extracts and gentamicin. The crude A. sativum extract was the only one that did not show any antagonism with the antimicrobial drugs. The results thus showed the potential use of these medicinal plants against E. coli strains, although antagonism with antimicrobial drugs is a negative aspect in the combined therapy of infectious diseases caused by E. coli.

Assessment of microbial faecal indicators was carried out in water and

Assessment of faecal pollution indicators (total coliforms, Escherichia coli, Enterococcus sp., sulphite reducing clostridia and Clostridium perfringens) was carried out in water samples collected during the XXIX Brazilian Antarctic Expedition and sediment samples from the XXX Brazilian Antarctic Expedition. Wastewater at di erent stages in the sewage treatment plant were also analyzed for ammonia, total phosphorus, phosphates, chemical oxygen demand (COD) and faecal indicators, in order to characterize the wastewater and evaluate the system performance. Water and sediment analysis showed low populations of faecal coliforms and the presence of the indicators in all sites, with higher frequencies and concentrations at EACF and Ullman Point sediment, indicating that a possible human impact is of low magnitude and cannot be di erentiated from interference caused by animal faeces. Assessment of the sewage treatment plant revealed that the wastewater produced at EACF has a typical faecal indicator composition and low contents of nutrients and COD, when compared to typical domestic sewage. Removal e ciency of COD was estimated in 20%, coliforms and enterococci removal varied from 84 to 98,7%, and no removal of nutrients was detected, indicating that the treatment process can be optimized.

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