Avicenna Journal of Clinical Microbiology and Infection
Volume:8 Issue: 1, Mar 2021

Microorganisms have potent activity for transferring antibiotic-resistant genes with either chromosomally- or plasmid-mediated characteristics. The purpose of this study was to isolate Lactobacillus from different commercial products and evaluate their potential in antibiotic-resistant development. Chromosomallyor plasmid-mediated resistant genes were investigated as well.

In total, Lactobacillus strains were isolated from 20 commercial dairy product samples such as cheese and yoghurt. The isolates were phenotypic and molecularly identified and their antibiotic-resistant properties were assessed by the disk-diffusion method. Finally, the plasmid-mediated antibiotic resistant characters of the isolates were evaluated by plasmid curing via evaluated temperatures and acridine orange methods.

Five strains Lactobacillus paracasei, L. rhamnosus, L. casei, L. plantarum, and L. fermentum were isolated different products. The results of the antibiotic susceptibility assay indicated that all strains were susceptible to amoxicillin and imipenem and resistant to ciprofloxacin and vancomycin. Furthermore, different responses were observed among the isolates against streptomycin and gentamicin. The evaluation of plasmid-mediated antibiotic resistance in the isolates revealed that streptomycin and gentamicin-resistant characters were of plasmid-mediated type in L. rhamnosus and L. plantarum strains.

In general, our finding demonstrated that some commercial Lactobacillus strains harboured antibiotic-resistant genes. These genes can be located either in chromosome or plasmid group. Hence, the frequency of antibiotic-resistant pathogenic bacteria might be increased after consuming some dairy products because of the horizontal transfer of antibiotic-resistance genes among the bacteria.

The antimicrobial resistance of pathogenic bacteria has emerged as a major health problem in recent years. Extensive research has been conducted to find new antimicrobial agents.

The aim of this study was to examine the antibacterial activities of benzohydrazide derivatives.

Manganese hydrogen sulfate choline chloride was applied in a simple method for synthesizing benzohydrazide derivatives.Antibacterial activities of the derivatives were assessed against Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, Bacillus subtilis, diphtheroids, Salmonella enterica, Serratia marcescens, Pseudomonas aeruginosa, and Klebsiella pneumoniae. The structure of the synthesized compounds was determined employing 1 H/13C NMR and Fourier-transform infrared (FT-IR) spectroscopy. The reactions were carried out in choline chloride dissolved in water at room temperature.

The results of this study showed that benzohydrazide derivatives had very desired antibacterial activities against the assessed bacteria.

Further investigations are required to assess the safety and efficacy of benzohydrazide derivatives as antibacterial agents in vivo and in vitro.

New drugs must be designed and synthesized for combating resistant pathogens. In this study, antibacterial and antifungal activities of 4 new derivatives of 1,3,4-oxadiazole were assessed against 8 bacterial and 2 fungal pathogens.

To this end, the cinnamic acid derivatives were dissolved in acetonitrile solvent and N-iso-cianoimino-triphenyl-phosphorane was added to the above-mentioned solution, followed by applying Petroleum ether and Ethyl acetate as solvent and base. Then, antimicrobial susceptibility tests were used to determine inhibition zone diameter, minimum inhibitory concentration, the minimum bactericidal concentration (MBC), and minimum fungicidal concentration (MFC) values.

The chemical structure of all compounds was characterized with infrared spectra, 1H-NMR, and 13C-NMR. A variety of inhibitory effects were observed by the synthesized compounds. Methoxyphenyl derivative (3c) affected bacterial strains, especially Streptococcus mutans. Other compounds also had antibacterial properties. Additionally, compound 3c showed the greatest effect on fungal samples, especially Aspergillus flavus.

In general, our new derivatives of 1,3,4-oxadiazole are able to destroy Gram-positive bacteria. In addition, developing new derivatives of 1,3,4-oxadiazole in future research can improve therapeutic properties. It seems that with the addition of other functional groups and increasing the destructive power of compounds, inhibitory effects on fungal samples can also be observed

Brucellosis, a deteriorating zoonotic disease, is very common in most parts of Iran. Consumption of contaminated milk and dairy products is one of the most significant ways for transmission of the infections to human. Since the close rearing of cattle and sheep is practiced in Kurdistan province of Iran, the infection of cow with non-specific species is not out of mind. The present study aimed to determine the frequency of bovine milk contamination with zoonotic Brucella spp.

A total of 240 milk samples, equally from traditional and industrialized dairy farms, were collected aseptically. Conventional microbiological method was used for isolation of the bacterium, followed by the genotypic identification of the isolates. Moreover, direct molecular processing of the samples was carried out for detection of the bacterial genome. The positive samples were further genotypically assessed to identify the contamination as Brucella abortus or Brucella melitensis.

In general, 16 (6.66%) and 15 (6.25%) of the samples were contaminated with Brucella spp. in phenotypic and genotypic methods, respectively. The proportion of contamination with B. abortus and B. melitensis in phenotypic and genotypic methods were 5% and 1.66%, and 5% and 1.25%, respectively. The overall rate of contamination in traditional milk samples was more than industrialized samples.

Contamination of bovine milk with Brucella spp. is a serious threat to public health in the studied region. Continuous vaccination, application of test and slaughter policy, and presumption of pasteurized milk and dairy products are highly recommended.

This study aimed to determine antibacterial activity of ethanolic extract of Matricaria chamomilla (chamomile), Malva sylvestris, and Capsella bursa-pastoris against multidrug-resistant (MDR) clinical isolates of Pseudomonas aeruginosa.

The plants were collected from Ziarat village of Gorgan, Iran in April 2019. The required parts of the plants were separated and completely dried in the shade. After grinding, extraction was performed by maceration method. The extract was dried at 37°C for 24 hours. To obtain a concentration of 50 mg/mL of each extract, 500 mg of the dried plant extract was dissolved in 10 mL 5% dimethyl sulfoxide and sterilized by filtration through a 0.45 µm membrane filter. For the antibacterial assay, agar well diffusion and broth microdilution methods were used.

Based on the results, ethanolic extracts of M. sylvestris and Capsella bursa-pastoris did not show any antibacterial activity against MDR P. aeruginosa isolates in both antibacterial assays. No inhibitory effect was observed for ethanolic extract of chamomile against P. aeruginosa isolates in agar well diffusion method as well. In broth microdilution method, the extract of chamomile leaves showed inhibitory effect and the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined as 12.5 and 25 mg/mL, respectively.

In this study, the extract of ethanolic chamomile leaves showed antibacterial activity against the MDR P. aeruginosa isolates. Thus, it can be used in the production of antibacterial agents, and it is a good option for protection against pathogenic microorganisms, as well as P. aeruginosa

Oxadiazoles are a group of anti-inflammatory compounds that have a wide range of activity due to their higher efficacy. Pseudomonas aeruginosa is an opportunistic pathogen and a major pathogen of nosocomial infections. This study aimed to evaluate the antibacterial and investigation of the molecular docking of new derivatives of 1, 3, 4-oxadiazole against P. aeruginosa, in vitro & in silico.

Four new derivatives were synthesized and added to our previous synthetic derivatives of 1, 3, 4-oxadiazole. The antibacterial activity of all derivatives was measured based on three standard species of P. aeruginosa using inhibition zone (IZ) and minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) methods. Then, employing the computational design of the drug by the molecular docking method, the inhibitory effect of synthetic compounds on the LasR regulatory protein of P. aeruginosa quorum sensing system was investigated, which plays an important role in regulating the expression of pathogenic genes in bacteria.

The chemical structures of new compounds were characterized by IR spectra and 1H-NMR. A variety of inhibitory effects were observed by the synthesized compounds – compound 4d and 4g, in particular. Also, the inhibitory effect of these two compounds on the LasR regulatory protein under the control of the quorum sensing system in P. aeruginosa was demonstrated by molecular docking.

The results of this study showed that the two compounds containing the functional group of naphthalene and fluorophenyl have a significant effect on the inhibition of P. aeruginosa, as well as on the LasR protein of this bacterium

Toxoplasmosis is a worldwide infection caused by Toxoplasma gondii, an obligate intracellular protozoan. It infects approximately one-third of the world’s population. This study was conducted to determine the anti-T. gondii antibodies (IgG and IgM) in the rural population of Qaemshahr, northern Iran, in 2019.

Serum samples of 350 individuals referred to the laboratories of the rural health centers in Qaemshahr, northern Iran, were collected from February to April 2019 and were assessed for anti-T. gondii antibodies (IgG and IgM) using the ELISA kits (Pishtazteb, Iran). The results were analyzed using the chi-square test.

Totally, 296 (84.57%, 95% CI: 80.07%-88.2%) out of 350 serum samples were positive for anti-T. gondii IgG antibody. There was a significant correlation between seropositivity of anti-T. gondii IgG antibody and age (P=0.000), contact with soil (P=0.000), and job. None of the samples were positive for anti-T. gondii IgM antibody. No significant association was observed between the seroprevalence of T. gondii and the gender, contact with the cat and other animals, and ingestion of undercooked meat, non-chlorinated water, undercooked egg, raw milk and vegetables.

Results of the study showed that the prevalence of toxoplasmosis was much higher among the rural individuals in Qaemshahr, northern Iran, than those previously reported from other areas of Iran. Therefore, efforts should be focused on public health education to reduce the risk of toxoplasmosis transmission especially in the high-risk groups in this region.