Tuberculosis vaccine developments and efficient delivery systems: A comprehensive appraisal

Despite the widespread use of the Bacillus Calmette-Guérin (BCG) vaccine, Mycobacterium tuberculosis (MTB) continues to be a global burden. Vaccination has been proposed to prevent and treat tuberculosis (TB) infection, and several of them are in different phases of clinical trials. Though vaccine production is in progress but requires more attention. There are several TB vaccines in the trial phase, most of which are based on a combination of proteins/adjuvants or recombinant viral vectors used for selected MTB antigens. In this review, we attempted to discuss different types of TB vaccines based on the vaccine composition, the immune responses generated, and their clinical trial phases. Furthermore, we have briefly overviewed the effective delivery systems used for the TB vaccine and their effectiveness in different vaccines.

Collateral sensitivity: An evolutionary trade-off between antibiotic resistance mechanisms, attractive for dealing with drug-resistance crisis

Background

The discovery and development of antimicrobial drugs were one of the most significant advances in medicine, but the evolution of microbial resistance limited the efficiency of these drugs.

Aim

This paper reviews the collateral sensitivity in bacteria and its potential and limitation as a new target for treating infections.

Results and Discussion

Knowledge mechanisms of resistance to antimicrobial agents are useful to trace a practical approach to treat and control of resistant pathogens. The effect of a resistance mechanism to certain antibiotics on the susceptibility or resistance to other drugs is a key point that may be helpful for applying a strategy to control resistance challenges. In an evolutionary trade-off known as collateral sensitivity, the resistance mechanism to a certain drug may be mediated by the hypersensitivity to other drugs. Collateral sensitivity has been described for different drugs in various bacteria, but the molecular mechanisms affecting susceptibility are not well demonstrated. Collateral sensitivity could be studied to detect its potential in the battle against resistance crisis as well as in the treatment of pathogens adapting to antibiotics. Collateral sensitivity-based antimicrobial therapy may have the potential to limit the emergence of antibiotic resistance.

The profile of key gut microbiota members and short-chain fatty acids in patients with sepsis

Sepsis is a complex clinical disorder with heterogeneous etiological factors. Given its high mortality rate, it is considered a global health issue. Recently, the link between gut microbiota and their metabolites, especially short-chain fatty acids, in the pathophysiology of sepsis has been reported. However, there are few findings to confirm this relationship. This study aimed to evaluate some key gut microbiota members, pathogenic bacteria, and short-chain fatty acids in non-ICU patients with sepsis caused by bacteremia compared to a control group. In this case-control study, 45 stool samples from patients with sepsis and 15 healthy persons were collected from October 2021 to August 2022 in Tabriz, Iran. The position of some gut microbiota members and the main short-chain fatty acids concentration were assessed in the two groups by the Q-PCR and the high-performance liquid chromatography system. Faecalibacterium prausnitzii and Bifidobacterium sp. As bacterial with protective features in non-ICU patients with sepsis decreased significantly. Moreover, the concentrations of acetic acid and propionic acid significantly decreased in this group compared to the healthy volunteers. In contrast, the pathogenic bacteria members such as Enterobacteriaceae and Bacteroides sp. Increased significantly in the patients compared to the healthy individuals. The concentration of butyric acid decreased in the patients, but this change was not significant in the two groups. Protective and immune functions of F. prausnitzii and Bifidobacterium sp., as well as acetate and propionate, are evident. In this investigation, this profile was significantly reduced in non-ICU patients with sepsis compared to the control group.

Short-chain fatty acids profile in patients with SARS-CoV-2: A case-control study

Background and Aims

SARS-CoV-2, as a new pandemic disease, affected the world. Short-chain fatty acids (SCFAs) such as acetic, propionic, and butyric acids are the main metabolites of human gut microbiota. The positive effects of SCFAs have been shown in infections caused by respiratory syncytial virus, adenovirus, influenza, and rhinovirus. Therefore, this study aimed to evaluate the concentration of SCFAs in patients with SARS-CoV-2 compared with the healthy group.

Methods

This research was designed based on a case and control study. Twenty healthy individuals as the control group and 20 persons admitted to the hospital with a positive test of coronavirus disease (COVID-19) real-time polymerase chain reaction were included in the study as the patient group from September 2021 to October 2021, in Tabriz, Iran. Stool specimens were collected from volunteers, and analysis of SCFAs was carried out by a high-performance liquid chromatography system.

Results

The amount of acetic acid in the healthy group was 67.88 ± 23.09 μmol/g, while in the group of patients with COVID-19 was 37.04 ± 13.29 μmol/g. Therefore, the concentration of acetic acid in the patient group was significantly (p < 0.001) lower than in the healthy group. Propionic and butyric acid were present in a higher amount in the control group compared with the case group; however, this value was not statistically significant (p > 0.05).

Conclusion

This study showed that the concentration of acetic acid as the metabolite caused by gut microbiota is significantly disturbed in patients with COVID-19. Therefore, therapeutic interventions based on gut microbiota metabolites in future research may be effective against COVID-19.

Antibacterial and biofilm-inhibitory effects of vancomycin-loaded mesoporous silica nanoparticles on methicillin-resistant staphylococcus aureus and gram-negative bacteria

The present study aimed to prepare and characterize vancomycin-loaded mesoporous silica nanoparticles (Van-MSNs) to detect inhibitory effects on the planktonic and biofilm forms of methicillin-resistant Staphylococcus aureus (MRSA) isolates, and study the biocompatibility and toxicity of Van-MSNs in vitro as well as antibacterial activity of Van-MSNs against Gram-negative bacteria. The inhibitory effects of Van-MSNs were investigated on MRSA using the determination of minimum inhibitory (MIC) and minimum biofilm-inhibitory concentrations (MBIC) as well as the effect on bacterial attachment. Biocompatibility was studied by examining the effect of Van-MSNs on the lysis and sedimentation rate of red blood cells (RBC). The interaction of Van-MSNs with human blood plasma was detected by the SDS-PAGE approach. The cytotoxic effect of the Van-MSNs on human bone marrow mesenchymal stem cells (hBM-MSCs) was evaluated by the MTT assay. The antibacterial effects of vancomycin and Van-MSNs on Gram-negative bacteria were also investigated using MIC determination using the broth microdilution method. Furthermore, bacteria outer membrane (OM) permeabilization was determined. Van-MSNs showed inhibitory effects on planktonic and biofilm forms of bacteria on all isolates at levels lower than MICs and MBICs of free vancomycin, but the antibiofilm effect of Van-MSNs was not significant. However, Van-MSNs did not affect bacterial attachment to surfaces. Van-loaded MSNs did not show a considerable effect on the lysis and sedimentation of RBC. A low interaction of Van-MSNs was detected with albumin (66.5 kDa). The hBM-MSCs viability in exposure to different levels of Van-MSNs was 91-100%. MICs of ≥ 128 µg/mL were observed for vancomycin against all Gram-negative bacteria. In contrast, Van-MSNs exhibited modest antibacterial activity inhibiting the tested Gram-negative bacterial strains, at concentrations of ≤ 16 µg/mL. Van-MSNs increased the OM permeability of bacteria that can increase the antimicrobial effect of vancomycin. According to our findings, Van-loaded MSNs have low cytotoxicity, desirable biocompatibility, and antibacterial effects and can be an option for the battle against planktonic MRSA.

Microbiota metabolites in the female reproductive system: Focused on the short-chain fatty acids

Several disorders have been linked to modifications in the gut microbial imbalance, intestinal epithelium, and host immune system. In this regard, microbiota derived short-chain fatty acids (SCFAs) play a key function in the regulation of histone deacetylases (HDACs), which affect modulation of immunity and regulation of inflammatory responses in the intestine and other organs. Studies examining the metabolites produced by polymicrobial bacterial vaginosis (BV) states and Lactobacillus-dominated microbiota have noted a dramatic reduction of lactic acid and a shift toward SCFA synthesis. Along with higher levels of SCFAs, acetate is typically the main metabolite in the cervicovaginal fluid of women with symptomatic bacterial vaginosis. The fact that SCFAs made by the vaginal microbiota have been shown to exhibit antibacterial and immune-modulating properties suggests that they may have promise as indicators of disease and/or disease susceptibility. In this review, we overview and summarize the current findings on the detrimental or protective roles of microbiota metabolites especially SCFAs in the health and disease of the female reproductive system.

Side Effects Comparison of Coronavirus Vaccines Among Healthcare Workers in Shoushtar, Iran

Objective

Vaccination is one of the effective ways to fight against COVID-19 disease. Various vaccines have been designed during the coronavirus pandemic. Each of the used vaccines has beneficial effects as well as side effects. Healthcare workers were among the first vaccinated persons against COVID-19 in different countries. The current study aims to compare the side effects of AstraZeneca, Sinopharm, Bharat, and Sputnik V on healthcare workers in Iran.

Methods

This descriptive study was conducted from July 2021 to January 2022 on 1639 healthcare workers who received the COVID-19 vaccines. Data were collected using a checklist that contained questions related to systemic, local, and severe side effects of the vaccine. The collected data were analyzed using the Kruskal-Wallis, Chi-square, and trend chi-square. P < .05 was regarded as a significant statistical difference.

Results

The most commonly injected vaccines were Sinopharm (41.80%), Sputnik V (36.65%), AstraZeneca (17.75%), and Bharat (3.80%), respectively. At least 37.5% of participants reported one complication. The most common side effects after 72 hours of the first and second doses were as follows: injection site pain, fatigue, fever, myalgia, headache, and chill. Overall complication rates were reported as follows: AstraZeneca (91.4%), Sputnik V (65.9%), Sinopharm (56.8%), and Bharat (98.4%). Bharat showed the highest overall side effects, while Sinopharm had the lowest overall side effects. Also, our results indicated that individuals with a previous history of positive COVID-19 infection had a higher rate of overall complications.

Conclusions

The majority of participants did not show life-threatening side effects after the injection of 1 of the 4 studied vaccines. Since it was well accepted and tolerable by the participants, it can be used widely and safely against SARS-CoV-2.

Antimicrobial and antibiofilm activities of meropenem loaded-mesoporous silica nanoparticles against carbapenem-resistant Pseudomonas aeruginosa

The aims of the present study were the determination of antimicrobial and antibiofilm effects of meropenem-loaded mesoporous silica nanoparticles (MSNs) on carbapenem resistant Pseudomonas aeruginosa (P. aeruginosa) and cytotoxicity properties in vitro. The meropenem-loaded MSNs had shown antibacterial and biofilm inhibitory activities on all isolates at different levels lower than MICs and BICs of meropenem. The viability of HC-04 cells treated with serial concentrations as MICs and BICs of meropenem-loaded MSNs was 92-100%. According to the obtained results, meropenem-loaded MSNs display the significant antibacterial and antibiofilm effects against carbapenem resistant and biofilm forming P. aeruginosa and low cell toxicity in vitro. Then, the prepared system can be an appropriate option for the delivery of carbapenem for further evaluation in vivo assays.

Prevalence of Legionella Species in Water Resources of Iran: A Systematic Review and Meta-Analysis

BACKGROUND

Legionella species are ubiquitous and naturally found in lakes, rivers, streams and hot springs, and other water resources. The present study aimed to investigate the prevalence of Legionella species in water resources of Iran by a systematic review and meta-analysis.

METHODS

In search of papers relevant to the prevalence of Legionella in water resources of Iran, the scientific information database in both English and Persian languages was used. The search was limited to studies between the year 2000 and end of July 2016. Each cohort and cross-sectional study that reported the contamination of water with Legionella was included in the present study. For data analysis, comprehensive meta-analysis software with Cochran's Q and I2 tests were used. P values less than 0.05 were considered statistically significant.

RESULTS

The prevalence of Legionella species in water resources of Iran was 27.3% (95% CI: 25.3-29.3). The prevalence of Legionella spp. in hospital water, dental settings water, and other water resources were 28.8% (95% CI: 26.4-31.2), 23.6% (95% CI: 16.1-33.2), and 29.6% (95% CI: 25.6-33.8), respectively. The most common Legionella species was L. pneumophila with a prevalence of 60.5% (95% CI: 53.3-67.2) and the prevalence of all other species was 52.5% (95% CI: 44.7-60.2). The highest prevalence was reported in Isfahan with 55.7% (95% CI: 48.0-63.0).

CONCLUSION

Based on the results, the prevalence rate of Legionella species in water resources of Iran was high and the most common Legionella species was L. pneumophila.

The protective effect of Lactobacillus and Bifidobacterium as the gut microbiota members against chronic urticaria

BACKGROUND

Chronic Urticaria is a common disorder which is defined by recurrent occurrence of wheals and sometimes angioedema. It has a notable influence on the patients' quality of life. Regulation of the immune system is one of the important roles of the gut microbiota. The effect of dysbiosis considering some members of gut microbiota in patients with chronic urticaria has been demonstrated in our previous study.

OBJECTIVE

Comparing the frequency and bacterial load of Lactobacillus, Bifidobacterium, and Bacteroides between patients with chronic urticaria and healthy controls.

METHODS

20 patients with chronic urticaria and 20 age and sex matched healthy individuals were included in the present study. Stool samples were analyzed for determining the frequency and bacterial load of Lactobacillus, Bifidobacterium, and Bacteroides genera.

RESULTS

There were no significant differences among the frequencies of detectable Lactobacillus, Bifidobacterium, or Bacteroides in stool samples of patients with chronic urticaria and healthy controls. The relative amounts of Lactobacillus and Bifidobacterium were significantly higher in fecal samples from controls compared to patients with chronic urticaria (P = 0.038 and 0.039, respectively).

CONCLUSION

It is the first study on the implication of Lactobacillus, Bifidobacterium, and Bacteroides genera as gut microbiota members in patients with chronic urticaria.

Association of altered gut microbiota composition with chronic urticaria

BACKGROUND

An altered gut microbiota composition has recently been linked to some types of allergies.

OBJECTIVE

To compare the relative amounts of Akkermansia muciniphila, Clostridium leptum, Faecalibacterium prausnitzii, and Enterobacteriaceae as members of gut microbiota among patients with chronic urticaria (CU) and healthy controls.

METHODS

A total of 20 patients with CU and 20 healthy individuals matched by age and sex participated in the study. Fresh fecal samples were collected, and DNA extracted from stool samples was analyzed by real-time polymerase chain reaction for the qualitative and quantitative assays of the so-called bacteria.

RESULTS

The frequencies of A muciniphila, C leptum, and F prausnitzii in healthy controls' stool samples were significantly more than those of patients with CU (P < .001, P < .01, and P < .05, respectively), whereas the Enterobacteriaceae family was detected in all patients and healthy controls' stool samples. The relative amounts of A muciniphila in healthy control positive samples were significantly higher than those of samples from patients with CU (P < .001). Furthermore, there was a corresponding increase of relative amounts of C leptum and F prausnitzii in healthy control positive samples compared with those of patients with CU (P = .09 and P = .08, respectively). The mean of the relative amounts of Enterobacteriaceae family in the stool samples from patients with CU was more than that of healthy controls; however, the difference was nearly significant (P = .12).

CONCLUSION

The results reveal a change of frequency and relative amounts of A muciniphila, C leptum, and F prausnitzii in patients with CU compared with healthy controls. This is the first study, to our knowledge, to show the change of microbiota composition in patients with CU.