José Pinto de Siqueira Júnior

Effectiveness of Lippia sidoides Cham. (Verbenaceae) essential oil in inhibiting the growth of Staphylococcus aureus strains isolated from clinical material

Staphylococcus aureus apresenta-se como um microrganismo patogenico classico sendo comumente reconhecido como agente etiologico de infeccoes comunitarias e hospitalares. Considerando o conhecimento acerca das propriedades biologicas apresentadas por Lippia sidoides Cham. (Verbenaceae), este estudo teve como objetivo avaliar a efetividade de seu oleo essencial em inibir o crescimento de cepas de S. aureus com diferentes perfis de resistencia antibiotica isoladas de material clinico. Os resultados mostraram destacavel atividade anti-S. aureus do oleo essencial de L. sidoides notada por grandes halos de inibicao do crescimento bacteriano (15-21 mm). A CIM encontrada foi de 0.4 µL/mL para todas as cepas ensaiada. A CIM apresentou destacavel efetividade de inibicao da viabilidade de S. aureus em caldo durante vinte e quatro horas de interacao caracterizando um efeito bacteriostatico. Estes resultados mostram a destacavel atividade antiestafilococica do oleo essencial de L. sidoides, bem como suportam a possibilidade de seu uso racional como agente antimicrobiano alternativo.

Biofilm formation by Staphylococcus aureus from food contact surfaces in a meat-based broth and sensitivity to sanitizers

This study assessed the capacity of adhesion, the detachment kinetic and the biofilm formation by Staphylococcus aureus isolated from food services on stainless steel and polypropylene surfaces (2 × 2 cm) when cultivated in a meat-based broth at 28 and 7 °C. It was also to study the efficacy of the sanitizers sodium hypochlorite (250 mg/L) and peracetic acid (30 mg/L) in inactivating the bacterial cells in the preformed biofilm. S. aureus strains adhered in high numbers regardless the assayed surface kind and incubation temperature over 72 h. Cells detachment of surfaces revealed high persistence over the incubation period. Number of cells needed for biofilm formation was noted at all experimental systems already after 3 days. Peracetic acid and sodium hypochlorite were not efficient in completely removing the cells of S. aureus adhered on polypropylene and stainless steel surfaces. From these results, the assayed strains revealed high capacity to adhere and form biofilm on polypropylene and stainless steel surfaces under different growth conditions. Moreover, the cells in biofilm matrix were resistant for total removal when submitted to the exposure to sanitizers.

In vitro evaluation of schistosomicidal activity of essential oil of Mentha x villosa and some of its chemical constituents in adult worms of Schistosoma mansoni.

This study aimed to determine the composition of the essential oil of Mentha x villosa and to evaluate its biological effects in vitro on adult worms of S. mansoni. Rotundifolone (70.96 %), limonene (8.75 %), trans-caryophyllene (1.46 %), and β-pinene (0.81 %) were shown to be the major constituents of this oil. Adult worms of S. mansoni were incubated with different concentrations of the essential oil (1, 10, 100, 250, 500, and 1000 µg/mL) and of its constituents rotundifolone (0.7, 3.54, 7.09, 70.96, 177.4, 354.8, and 700.96 µg/mL), limonene (43.75 µg/mL), trans-caryophyllene (7.3 µg/mL), and β-pinene (4.03 µg/mL). No schistosomicidal activity was identified at the trans-caryophyllene and β-pinene concentrations studied. However, use of the essential oil (10 µg/mL), rotundifolone (7.09 µg/mL), and limonene (43.75 µg/mL) resulted in decreased worm motility continuing until 96 hours of observation. At higher concentrations (100 and 70.96 µg/mL, respectively), both the essential oil and rotundifolone caused mortality among adult worms of S. mansoni. The positive control praziquantel caused the death of all parasites after 24 h of evaluation. The results from this study suggest that the essential oil of Mentha x villosa presents schistosomicidal efficacy.

Eliminação de resistência a drogas por fluorquinolonas em Staphylococcus aureus de origem bovina

Bovine strains of Staphylococcus aureus were submitted to treatment with four fluoro-quinolones in subinhibitory concentrations (1/2 x MICs) to evaluate their influence on the curing of plasmids. Ciprofloxacin showed to be the most efficient by eliminating resistance to streptomycin, tetracyclin, penicillin, and cadmium nitrate. Norfloxacin and pefloxacin eliminated penicillin- and tetracyclin-resistance respectively. Otherwise, plasmids elimination by ofloxacin was not evidenced. The results obtained in this study confirm the potential of fluoroquinolones to eliminate antibiotic-resistant plasmids, and showed to be a valuable contribution for the prevention of multi-resistant strains, and may even enhance their sensitivity to other chemotherapeutic agents.

Synthesis and evaluation of the antibiotic and adjuvant antibiotic potential of organotin(IV) derivatives

A series of organotin(IV) derivatives was investigated in vitro for their antibiotic and adjuvant antibiotic properties (efflux pump inhibitors) against Staphylococcus aureus strains that overexpress efflux pump proteins for norfloxacin (SA-1199B), erythromycin (RN-4220) and tetracycline (IS-58). Most organotin(IV) compounds showed significant antibacterial activity with small Minimum Inhibitory Concentration (MIC) values, some of which were close to 1.0μg/mL (3.1μM), but this feature was also associated with substantial cytotoxicity. Nevertheless, the cytotoxicity of these organotin(IV) compounds can be overcome when they are used as antibiotic adjuvants. Their remarkable adjuvant antibiotic properties allow potentiation of the action of tetracycline (against IS-58 strain) by up to 128-fold. This likely indicates that they can act as putative inhibitors of bacterial efflux pumps. These results reinforce organotin(IV) complexes as promising antibacterial agents, and many of these complexes, if associated with antibiotics, can act as potential adjuvant antibiotic candidates.

Habituation of enterotoxigenic Staphylococcus aureus to Origanum vulgare L. essential oil does not induce direct-tolerance and cross-tolerance to salts and organic acids

Enterotoxigenic Staphylococcus aureus strains that were isolated from foods were investigated for their ability to develop direct-tolerance and cross-tolerance to sodium chloride (NaCl), potassium chloride (KCl), lactic acid (LA) and acetic acid (AA) after habituation in sublethal amounts (1/2 of the minimum inhibitory concentration - 1/2 MIC and 1/4 of the minimum inhibitory concentration - 1/4 MIC) of Origanum vulgare L. essential oil (OVEO). The habituation of S. aureus to 1/2 MIC and 1/4 MIC of OVEO did not induce direct-tolerance or cross-tolerance in the tested strains, as assessed by modulation of MIC values. Otherwise, exposing the strains to OVEO at sublethal concentrations maintained or increased the sensitivity of the cells to the tested stressing agents because the MIC values of OVEO, NaCl, KCl, LA and AA against the cells that were previously habituated to OVEO remained the same or decreased when compared with non-habituated cells. These data indicate that OVEO does not have an inductive effect on the acquisition of direct-tolerance or cross-tolerance in the tested enterotoxigenic strains of S. aureus to antimicrobial agents that are typically used in food preservation.

Dolastane diterpenes from Canistrocarpus cervicornis and their effects in modulation of drug resistance in Staphylococcus aureus

Abstract One new diterpene (4R,7R,14S)-4α,7α-diacetoxy-10-one-14α-hydroxydolasta-1(15),8-diene (1), and five known compounds (4R,7R,14S)-4α,7α-diacetoxy-14α-hydroxydolasta-1(15),8-diene (2), (4R,14S)-4α,14α-dihydroxydolasta-1(15),8-diene (3), (4S,9R,14S)-4α-acetoxy-9β,14α-dihydroxydolasta-1(15),7-diene (4), 4-acetoxy-14-hydroxydolasta-1(15),7,9-triene (5) and isolinearol (6), were isolated from Canistrocarpus cervicornis. In this study, dolastane diterpenes were isolated from the alga C. cervicornis and evaluated as modifiers of antibiotic activity in Staphylococcus aureus: SA-1199B, which overexpresses the norA gene RN-4220, which encodes for the protein efflux of macrolides (MRSA), and IS-58 which has the gene encoding the protein TetK. The minimum inhibitory concentrations (MICs) for norfloxacin, tetracycline and erythromycin were determined by the microdilution broth nutrient in the absence and presence of diterpenes at a sub-inhibitory concentration (MIC/4). The extracts of C. cervicornis and isolated diterpenes showed no antibacterial activity, but showed modulatory activity, decreasing the MIC of antibiotics by 4–256 fold. The results indicate that seaweed extracts and diterpenes are potential sources of antibiotic adjuvant, acting as potential inhibitors of efflux pump.

In vitro anti-Candida activity and mechanism of action of the flavonoid isolated from Praxelis clematidea against Candida albicans species

The prevalence of candidiasis in the world is high. Candida species are able to create superficial and systemic infections. Candida albicans is an opportunistic pathogen, causing mycoses in immunocompromised patients as well as long-term antibiotic users. The present study objective was to evaluate in vitro anti-Candida effect of this compost isolated from Praxelis clematidea. The minimum inhibitory concentration (MIC) and the minimum fungicidal concentration (MFC) were determined by the broth microdilution techniques. We also investigated possible flavonoid 5,7,4´trimethoxflavone (TMF) action on cell walls (0.8 M sorbitol) and cell membranes (TMF to ergosterol binding). The MIC50 of flavonoid were 64 𝜇g/mL and tha MFC50 was 64 𝜇g/mL. Involvement with the cell wall and ergosterol binding were comproved as possible mechanisms of action. In conclusion the flavonoid showed in vitro antifungal potential against strains of C. albicans.

Lack of Induction of Direct and Cross Tolerance To Salts and Organic Acids in Enterotoxigenic Staphylococcus Aureus After Habituation To Origanum Vulgare L. Essential Oil

Adassa Gama Tavares, Daniel Farias Marinho do Monte, Kataryne Arabe Rima de Oliveira, Tereza Cristina Rocha Moreira de Oliveira, Marciane Magnani, Jose Pinto de Siqueira Junior, Evandro Leite de Souza. Lack of Induction of Direct and Cross Tolerance To Salts and Organic Acids in Enterotoxigenic Staphylococcus aureus After Habituation To Origanum Vulgare L. Essential Oil. In: Anais do 12o Congresso Latinoamericano de Microbiologia e Higiene de Alimentos MICROAL 2014 [= Blucher Food Science Proceedings, num.1, vol.1]. Sao Paulo: Editora Blucher, 2014. DOI 10.5151/foodsci-microal-303 Lack of Induction of Direct and Cross Tolerance To Salts and Organic Acids in Enterotoxigenic Staphylococcus aureus After Habituation To Origanum Vulgare L. Essential Oil

Drug resistance profile of staphylococci isolated from asymptomatic adults

Dear Editor, The emergence of multi-drug resistant (MDR) strains is a worldwide phenomenon, due to the selective pressure exerted by extensive use of antibiotics, which has hindered the treatment of staphylococcal infections. The anterior nasal vestibule and the throat are the main reservoirs of S. aureus, including methicillin-resistant S. aureus (MRSA) strains, which show a genetic predisposition to develop MDR phenotype and are a common cause of hospitaland communityacquired infections worldwide.1,2 The maintenance of the asymptomatic nasal carrier state is considered a risk factor for staphylococcal disease acquisition and staphylococci transmission to susceptible individuals. The resistance profile of staphylococci present in the nasal vestibule of asymptomatic carriers was analyzed in the city of Natal, northeastern Brazil. These strains were isolated from nasal secretion samples collected from 52 students of dentistry. 59.6% (31/52) of isolates were identified as S. aureus, of which 6.5% (2/31) were MRSA strains. The Letter to the Editor