Effects of nisin on the expression of virulence genes of methicillin-resistant/sensitive Staphylococcus aureus.

Background and Objectives: Few studies have considered potential benefits of probiotic bacteria and their derivatives on human and animal health. Nisin is an antimicrobial agent that is produced by lactobacilli and served as a preservative in foods. This study aims to investigate whether nisin suppresses or decreases the genes involved in the pathogenicity of methicillin-susceptible and methicillin-resistant Staphylococcus aureus (MSSA and MRSA). Materials and Methods: MSSA and MRSA strains were cultured at the », ½, and 1 × minimum inhibitory concentration (MIC) of nisin. Next, RNA extraction was performed at the mid-exponential stage of growth, and cDNA was synthesized. The expression of virulence factors was measured by qPCR, and the data were analyzed by the ΔΔCt formula. Results: Depending on the incubation times and the Lactobacillus species, the MIC of nisin on MRSA and MSSA observed in 800 and 1600 mg/l, respectively. The qPCR assay showed the expression level of the sea, agrA, and spa genes decreased and the level of the sae gene increased at the sub-MIC of nisin, and no antagonism was observed. Concerning MRSA, the maximum downregulation rate was observed in the sea gene (up to 5.9 folds) while in MSSA, the maximum downregulation rate was noticed in the agrA gene (up to 10 folds). Conclusion: Due to the high inhibitory effect of the sub-MIC of nisin on the expression of virulence factor genes in MRSA and MSSA, this compound could potentially reduce the virulence of S. aureus.

A Review of Immunomodulatory Effects of Fluoroquinolones.

Past researches indicate that some types of antibiotics, apart from their antimicrobial effects, have some other important effects which indirectly are exerted by modulating and regulating the immune system's mediators. Among the compounds with antimicrobial effects, fluoroquinolones (FQs) are known as synthetic antibiotics, which exhibit the property of decomposing of DNA and prevent bacterial growth by inactivating the enzymes involved in DNA twisting, including topoisomerase II (DNA gyrase) and IV. Interestingly, immune responses are indirectly modulated by FQs through suppressing pro-inflammatory cytokines, such as interleukin 1 (IL-1), IL-6, tumor necrosis factor-alpha (TNF-α), and super-inducing IL-2, which tend to increase both the growth and activity of T and B lymphocytes. In addition, they affect the development of immune responses by influencing of expression of other cytokines and mediators. This study aims to review past research on the immunomodulatory effects of FQs on the expression of cytokines, especially IL-2 and to discuss controversial investigations.

Resistance pattern of Escherichia coli to levofloxacin in Iran: a narrative review.

Fluoroquinolones (FQs) are widely used in the treatment of infections caused by Escherichia coli. FQs are broad spectrum antibiotics with high tissue penetration, and ease of use. Therefore, given the concerns existing about drug resistance, we aim to review the latest findings about resistance patterns to levofloxacin (LVX) along with other FQs in E. coli infections in different parts of Iran. Evidence shows that quinolones have been used in Iran for nearly 50 years, and that 0-65% of E. coli isolates show resistance to FQs. In the western parts of Iran, the highest rate of resistance to LVX (66.7%) has been reported among patients having urinary tract infections with E. coli isolates. Few studies and information exist on the antimicrobial resistance of E. coli to LVX in different geographical locations of Iran. However, the findings of various studies on this subject show that E. coli resistance to LVX is more in the western part of Iran than in central and southern regions, but it is similar among inpatients and outpatients. Therefore, it is reasonable advisable to limit the overuse, inappropriate prescription, and self-medication of LVX to prevent the induction of FQ-resistant strains. Accordingly, in order to obtain a clearer image of resistance to FQs, especially LVX in E. coli in Iran, more extensive investigations in different geographical locations and periods of time are required. In addition, antimicrobial stewardship would be helpful in this regard.

TGF-ß in Toxoplasmosis: Friend or foe?

Toxoplasma gondii (T. gondii) is an obligate intracellular protozoan causing several forms of toxoplasmosis in humans. The main mechanisms that allow the development of the prolonged forms of the disease and its subsequent pathology are yet to be clarified. However, many researchers have hypothesized that immunological and genetic parameters may play crucial roles in the etiology of the disease. Transforming growth factor beta (TGF-ß) is a cytokine with a dual role in the regulation of immune responses including those against parasites. However, the relationship between TGF-ß and immune responses against T .gondii are not fully understood. The important roles played by TGF-ß in the development of Th17 and T regulatory lymphocytes, mucosal immunity and regulation of immune responses have been documented and this provides insights into TGF-ß function during parasitic infections such as toxoplasmosis. Therefore, the aim of this review is to collate the current information regarding the status and association of TGF-ß with T. gondii infection.

Significant roles played by IL-10 in Chlamydia infections.

Chlamydia species are obligate intracellular parasites which cause usually asymptomatic genital tract infections and also are associated with several complications. Previous studies demonstrated that immune responses to Chlamydia species are different and the diseases will be limited to some cases. Additionally, Chlamydia species are able to modulate immune responses via regulating expression of some immune system molecules including cytokines. IL-10, as the main anti-inflammatory cytokine, plays important roles in the induction of immune-tolerance against self-antigen and also immune-homeostasis after microbe elimination. Furthermore, it has been documented that ectopic expression of IL-10 is associated with several chronic infectious diseases. Therefore, it can be hypothesized that changes in the regulation of this cytokine can be associated with infection with several species of Chlamydia and their associated complications. This review collected the recent information regarding the association and relationship of IL-10 with Chlamydia infections. Another aim of this review article is to address recent data regarding the association of genetic variations (polymorphisms) of IL-10 and Chlamydia infections.

T helper and B cell escape mutations within the HBc gene in patients with asymptomatic HBV infection: a study from the South-Eastern region of Iran.

BACKGROUND: Escape mutations potentially allow viruses to avoid detection and clearance by the host immune system and may represent a mechanism through which infections may persist in some patients. The association of the mutations in the HBcAg gene with Hepatitis B asymptomatic carriers (ASC) has not been studied adequately. The current study was aimed to investigate HBcAg18-27 CTL epitope mutations in ASC patients in the South-Eastern region of Iran. METHODS: 100 ASC patients were selected for this study and screened for HLA-A2 using flow cytometry. HBV-DNA was extracted from the HLA-A2 positive patients and the HBc gene was amplified using PCR. Direct double sequencing was performed to analyse mutations in the HBc gene of HBV isolates from patients with ASC. RESULTS: Overall, 25 (25%) of individuals were HLA-A2 positive. Direct double sequencing indicated no mutations in the HBcAg18-27 epitope. However, four mutations within the T helper and three mutations within the B cell epitopes of ASC patients were identified. CONCLUSIONS: The lack of mutations within the HBcAg18-27 epitope suggests that the antigenicity of this region is not altered in HBV isolates of our patients and therefore antigen presentation would occur normally to the patient's immune system through HLA-A2. However, in the course of this study we revealed some novel mutations within the T helper and B cell epitopes that may affect the efficiencies of immune response of ASC patients against these novel HBV epitopes.

Occult hepatitis B virus (HBV) infection: a global challenge for medicine.

Hepatitis B virus (HBV) is a serious risk as a disease that can be spread through blood transfusion. Occult hepatitis B infection (OBI) is defined in a patient with the presence of HBV-DNA but a lack of HBsAg in the serum and hepatocytes. OBI can be considered as a high potential risk factor for inducing post transfusion hepatitis (PTH), hepatocellular carcinoma (HCC), cirrhosis, and reactivation of the HBV. Recently, several investigations from various regions of the world have reported PTH as well as HCC and cirrhosis among blood recipients with diseases such as thalassemia and other disorders requiring regular hemodialysis. This form of hepatitis also causes complications for individuals that are co-infected with other viruses such as HCV and HIV. Because of its extreme disease potential, OBI can be considered a high risk for PTH, HCC, and cirrhosis. Therefore, an understanding of the prevalence of OBI among blood donors is a critical strategy in most transfusion services. This review addresses the recent information regarding the prevalence of OBI worldwide, with an additional focus on Iranian blood donors.

Post-transfusion-transmitted hepatitis C virus infection: a study on thalassemia and hemodialysis patients in southeastern Iran.

Thalassemia and hemodialysis patients are at risk of blood-transmitted infections due to their long-term need for blood transfusion. Nowadays, control of viral infections, including HCV infections, is one of the main tasks of blood transfusion services worldwide. Therefore, the aim of this research was to investigate the prevalence of HCV infection in thalassemia and hemodialysis patients in Kerman, in southeastern Iran. In this cross-sectional experimental study, 384 (203 hemodialysis and 181 thalassemia) patients were examined for HCV infection. Demographic data were also collected by questionnaire, and HCV infection was screened by enzyme-linked immunosorbent assay (ELISA) and confirmed by reverse transcriptase-polymerase chain reaction (RT-PCR). Data were analyzed by chi-square and t-test. Our results showed that 81 (44.7%) thalassemia and 64 (31.5%) hemodialysis patients were infected with HCV. There was a significant relationship between HCV positivity and the frequency of blood transfusion and the duration of dialysis in thalassemia and hemodialysis patients, respectively. Based on our results, the prevalence of HCV infection in thalassemia and hemodialysis patients in the southeastern part of Iran is higher than the other parts. Therefore, it is suggested that clinical and health authorities in southeastern Iran should pay more attention to preventing the transmission of HCV through blood and blood components.

An in vitro antimicrobial activity of ten Iranian-made toothpastes.

BACKGROUND: Antimicrobial agents have been used as a chemotherapeutic agent to improve oral health. This in vitro study was carried out to determine the antimicrobial activity of ten Iranian-made toothpastes against commonly found bacteria in the oral cavity. METHODS: The microorganisms used in this study were Streptococcus mutans, Streptococcus sanguis, Actinomyces viscosus and Candida albicans. Sterile discs impregnated with 10 Iranian-made toothpastes; Paveh, Saviz, Latifeh II, Bath, Darugar II, Darugar I, Close up, Tage, Pooneh III and Nasim, which were separately used on agar plates. Crest Cavity Protection toothpaste and Sterile pyrogenfree distilled water were used as positive and negative controls, respectively. The samples were tested in triplicate, at full strength, 1:1 and 1:3 dilutions. Inhibition zones were measured in millimeter after 48 hr. The data were analyzed by the ANOVA and t-test. RESULTS: All tested toothpastes demonstrated an antimicrobial activity. The antimicrobial activity of Bath on S. mutans, Paveh on S. sanguis, Paveh, Saviz, Latifeh III and Darugar II on C. albicans were similar to the activity of Crest Cavity Protection. The antimicrobial activity of Pooneh III and Nasim on S. mutans, Bath on S. sanguis and A. viscosus, and Bath and Pooneh III on C. albicans were significantly higher and the others were significantly lower than the positive control. While, the activity of Crest Cavity Protection was the same as Pooneh III, it showed a weaker activity compared with Bath. CONCLUSION: Apart from Bath and Pooneh III, the other Iranian-made toothpastes tested in this study showed a lower antimicrobial activity compared to Crest Cavity Protection.