Jundishapur Journal of Microbiology
Volume:13 Issue: 5, May 2020

Listeria monocytogenes is a food-borne pathogen with strong environmental adaptability. It can survive at high temperatures and in acidic high-salt and other unfavorable stressful environments and consequently form a biofilm.

This study aimed to explore the roles of lmo2672 on the environmental adaptability, biofilm formation, and motility of L. monocytogenes.

We analyzed the molecular characteristics of lmo2672 protein, constructed a lmo2672 gene deletion strain of L. monocytogenes strain (L. monocytogenes-Δlmo2672), using the homologous recombination technique and compared the environmental adaptability, biofilm formation, and motility of L. monocytogenes-Δlmo2672 with its parental strain L. monocytogenes EGD-e. The impacts of lmo2672 gene deficiency on the transcription of genes associated with flagella formation and the environmental adaptability of L. monocytogenes were also determined.

The results showed that the lmo2672 contains two helix-turn-helix (HTH) DNA-binding domains. Compared to L. monocytogenes EGD-e, L. monocytogenes-Δlmo2672 grew significantly slower at different temperatures (37°C and 42°C) under different osmotic pressures (5% and 8% NaCl) and in different media containing 0.3% bile salts, 5 mM H2O2, or 1% Triton X-100 (P < 0.05). Moreover, LM-Δlmo2672 showed a significant decrease in biofilm formation (P < 0.01) and motility (P < 0.05) at 48 h of culture. Furthermore, the transcriptional levels of regulatory gene prfA and flagella-related genes motA, fliP and fliE significantly decreased in LM-Δlmo2672 (P < 0.05).

In general, these findings indicated that lmo2672 played critical regulatory roles in the environmental adaptability, biofilm formation, and motility of L. monocytogenes, thus providing new insights into the regulatory mechanism of lmo2672 in L. monocytogenes.

Candida albicanss has been introduced as one of the most common causes of nosocomial infections. Molecular typing methods are powerful tools in epidemiology to investigate the infection source of candidiasis, identify the transmission routes, and control the measures.

This study aimed for genotyping C. albicans species isolated from oral cavities of the non-HIV patients who suffer from oropharyngeal candidiasis via combined ABC and repeat sequences (RPS) typing systems.

In this study, 31 DNA samples of clinical isolates of C. albicans were evaluated in terms of 25s ribosomal DNA region sequence or ABC typing, and ALT repeats numbers within RPS. DNA was amplified in two separate reactions, and the PCR products were electrophoresed to identify the genotypes of the isolates. Based on the band's pattern, phylogenetic analysis was conducted by UPGMA, and the discriminatory power of ABC and RPS typing was measured by Simpson’s index of diversity.

Genotype A with (14 isolates, 45.2%) were the most frequent and followed by genotype B (10 isolates, 32.3%) and Genotype C (7 isolates, 22.6%), respectively. In addition, genotype 3 with 25 isolates (80.6%) were the most prevalent, followed by genotype 2/3 (4 isolates, 12.9%) and genotype 3/4 (2 isolates, 6.5%) respectively. No significant relationship was found between the obtained genotypes and drug-resistant isolates (P < 0.05).

This study showed that 25s rDNA and RPS typing is a quick, simple, and cost-effective method with average discriminatory power and good reproducibility for C. albicans genotyping. It can be used for the epidemiology of C. albicans infections.

Silver nanoparticles (AgNPs) have received great attention in the biomedical field because of their intrinsic therapeutic properties. Nanoparticles synthesized from silver have been studied as antimicrobial, antiviral and anticancer agents and found particularly an attractive source for the development of a new and advance group of antimicrobial agents.

In the present study, silver nanoparticles were synthesized from non-pathogenic Bacillus subtilis strain to assess their antimicrobial activity.

Different strains of Bacillus spp. were selected and screened against silver nitrate (AgNO3) toxicity. Finally, B. subtilis strain (FCBP-WB-0174) was selected based on its silver resistant nature, among other strains. Silver nanoparticles were synthesized and optimized from the supernatant of B. subtilis culture at 37°C by the reduction of silver ions using the various molar concentration of AgNO3. The synthesized AgNPs were characterized by UV-Vis spectrophotometry and scanning electron microscopy (SEM). These synthesized AgNPs were used for evaluating antimicrobial activity against four multidrug-resistant bacterial strains.

The silver ion reduction was found at a ratio of 1:1 from all the three molar concentrations (1, 2, and 3 mM) of AgNO3. The characterized nanoparticles were found to have a characteristic absorption peak at 426 nm, and the particles were found to have spherical shape under SEM with an average diameter of about 80 ± 0.18 nm, which was also reconfirmed using Zeta Sizer Nano. Prepared Silver nanoparticles have found potential antimicrobial activities against all tested pathogenic, including strains, e.g., Acinetobacter baumannii, Pseudomonas aeruginosa, Methicillin-Resistant Staphylococcus aureus(MRSA) and Escherichia coli.

Effective AgNP’s were produced from selected B. subtilis strain, and the strain itself was resistant to AgNO3. The current study evidenced that biologically synthesized silver nanoparticles from B. subtilis has promising antimicrobial activities against pathogenic and multidrug-resistant bacteria.

Hepatitis C virus (HCV) infection can lead to a number of disorders and subsequent failures, including chronic liver disease and cancer. Genotype rs12979860 CC is an interleukin 28B gene polymorphism associated with an adequate response to treatment in HCV patients. However, its response quality varies in different races and populations.

The present study aimed to investigate this polymorphism in the Iranian population.

In this study, 120 volunteers were evaluated as patient subjects and 120 volunteers as the control subject group. The collected serum samples were examined by the PCR-RFLP technique and the frequency of polymorphism at rs12979860 was tested in both groups.

The findings of this study showed that the risk of HCV infection in the subjects with CC genotype of IL-28B gene was less than (OR = 2.000, P = 0.009) that of subjects with other genotypes of rs12979860 polymorphism, including CT and TT. The frequency of genotypic variations of rs12979860 gene in patients were as CC = 33.3%, CT = 43.3%, TT = 23.3%, and in healthy subjects accorded with CC = 50%, CT = 32%, TT = 17%. A significant difference was also observed between the two healthy and HCV suffering groups in terms of gender (P < 0.02).

In HCV patients, the frequency of CC variation in IL-28B rs12979860 gene leads to a more effective response to treatment than other genotypes in HCV patients. Also, the frequency of CC in healthy people was higher than patients.

Considering the increasing number of patients referred to gastroenterology clinics, we report a suspected case of coronavirus disease 2019 (COVID-19) with only gastrointestinal (GI) presentation in Qom, Iran.

A 74-year-old man with epigastric pain, diarrhea and vomiting for one week was treated, based on the routine abdominal treatment protocol. Since all GI symptoms were resistant to therapy, we decided to perform laboratory assays for a more accurate diagnosis of the disease. Considering the persistence of abdominal pain and nausea, abdominal and pelvic computed tomography (CT) scans, as well as endoscopy and colonoscopy, were performed. After performing the chest CT scan, we noticed the involvement of the lungs. The patient did not have any respiratory symptoms, and at the time of his hospitalization, the COVID-19 epidemic had been reported in Iran. With the progression of the disease, he started to experience mild fever (38°C). Using a specific COVID-19 kit, he was diagnosed with COVID-19 after precise evaluations. However, without any medications, all of his symptoms subsided after 2 - 3 weeks.

It is important for all physicians to know that some pure GI symptoms, which are resistant to therapy, may be the only symptoms in suspected COVID-19 patients. Timely diagnosis and isolation of these patients can guarantee population to avoid the spread of this highly contagious infection.