In vitro antibacterial effects of silver nanoparticles synthesized using Verbena officinalis leaf extract on Yersinia ruckeri, Vibrio cholera and Listeria monocytogenes.

BACKGROUND AND OBJECTIVES: The use of plants for the synthesis of nanoparticles has received attention. The present study aimed to evaluate the antibacterial effects of silver nanoparticles synthesized by Verbena officinalis leaf extract against Yersinia ruckeri, Vibrio cholerae and Listeria monocytogenes. MATERIALS AND METHODS: Silver nanoparticles were obtained by reacting silver nitrate solution 2 mM and V. officinalis leaf extract. The AgNPs were characterized by UV-visible spectrophotometer, scanning electron microscopy (SEM), and Fourier transform infrared spectrometer (FTIR). To determine minimum inhibitory concentration and test antibiogram of nanoparticle synthesized, broth micro dilution and agar well diffusion methods were used, respectively. RESULTS: The zones of bacterial inhibition were 16 ± 0.5 and 9.16 ± 0.28 mm against Y. ruckeri and L. monocytogenes using 10 and 0.62 mg/mL AgNPs, respectively. Among the studied bacterial species, silver nanoparticles were more effective on Y. ruckeri and L. monocytogenes and less effective on V. cholerae. The highest MIC and MBC of AgNPs (2.5 and 5 mg/mL) were observed for V. cholerae. The lowest MIC and MBC of AgNPs (0.32 and 0.62 mg/mL) were observed for Y. ruckeri, respectively. The MIC and MBC of AgNPs were found to be 1.25 and 2.5 mg/mL for L. monocytogenes. CONCLUSION: The results clearly indicated that V. officinalis AgNPs have potential antimicrobial activity against Gram-positive and Gram-negative bacteria.

Antibacterial Activity of Some Plant Extracts Against Extended- Spectrum Beta-Lactamase Producing Escherichia coli Isolates.

BACKGROUND: The extended-spectrum beta-lactamase (ESBL) -producing Escherichia coli isolates make many serious infections, especially urinary tract infections. OBJECTIVES: The purpose of this study was to determine the antibacterial activities of some natural plant extracts against ESBL-producing E. coli isolates, which harbor the TEM gene in urine samples of the patients who have urinary tract infections. MATERIALS AND METHODS: Evaluation has to be exactly determined for both methods of disk diffusion test and polymerase chain reaction (PCR), separately. We evaluated 120 strains of E. coli isolates from the urine culture of the patients in Boo-Ali Hospital (Zahedan, south-eastern Iran) who were suffering from urinary tract infections. The ESBL-producing E. coli isolates were evaluated by disk diffusion test and PCR through TEM gene detection. The minimal inhibitory concentration (MIC) of commonly used antibiotics including ceftazidime, ceftriaxon, amikacin, gentamicin and ciprofloxacin along with the MIC of the alcoholic extract of different natural plants including Myrtus communis L (Myrtaceae), Amaranthus retraflexus (Amaranthaceae), Cyminum cuminum L (Apiaceae), Marrubium vulgare (Laminaceae) and Peganum. harmala (Zygrophyllaceae) against the ESBL-producing E. coli isolates, which harbor the TEM genes, were determined using the microdulition method. RESULTS: Results of this study showed that in disk diffusion method, 80 samples of E. coli produced ESBLs. In PCR method, the TEM gene distribution in the isolated ESBL-producing organisms was 50 (41.6%). Amikacin was the most effective anti-bacterial agent and ciprofloxacin was the least effective against E. coli isolates. All the natural plant extracts mentioned above, especially P. harmala, were effective against the selected isolates of ESBL-producing E. coli. The most frequent ESBL rate producing E. coli isolates (32 out of 50) had MIC of 2.5 mg/mL in ethanol extract of P. harmala. CONCLUSIONS: The alcoholic extract of P. harmala was very effective against the selected ESBL-producing E. coli isolates harboring the TEM gene. Therefore, it could be suggested as an antibacterial agent in the future. More researches are necessary for detecting the mechanism of this plant's behavior and its pharmacological effects.

Antibacterial activity of ethyl acetate and aqueous extracts of Mentha longifolia L. and hydroalcoholic extract of Zataria multiflora Boiss. plants against important human pathogens.

OBJECTIVE: To determine the potential antibacterial activity of ethyl acetate and aqueous extracts from Mentha longifolia L. (M. longifolia) and hydroalcoholic extract of Zataria multiflora Boiss. (Z. multiflora) against important human pathogens. METHODS: Pseudomonas aeruginosa, Shigella dysenteriae, Klebsiella pneumoniae (K. pneumonia), Enterobacter cloacae, Salmonella typhi, Proteus mirabilis, Serratia marcescens, Bacillus cereus, Staphylococcus saprophyticus and Staphylococcus aureus were kinds of pathogenic bacteria to determine the antibacterial effect of aqueous and ethyl acetate extracts of M. longifolia and hydroalcoholic extract of Z. multiflora using broth microdiluation method. RESULTS: The lowest minimum inhibitory concentration and minimum bactericidal concentration values for K. pneumonia and Pseudomonas aeruginosa (1.25 and 2.5 mg/mL) were observed by the hydroalcoholic extract of Z. multiflora and the lowest minimum inhibitory concentration and minimum bactericidal concentration values for K. pneumonia and Serratia marcescens (2.5 and 5 mg/mL) were observed by the aqueous extracts of M. longifolia. CONCLUSIONS: In conclusion, it seems that Z. multiflora and M. longifolia extracts could inhibit the growth of all of the mentioned bacteria.