Prevalence of the CRISPR-cas system and its association with antibiotic resistance in clinical Klebsiella pneumoniae isolates.

BACKGROUND AND OBJECTIVE(S): CRISPR-Cas is a prokaryotic adaptive immune system that protects bacteria and archaea against mobile genetic elements (MGEs) such as bacteriophages plasmids, and transposons. In this study, we aimed to assess the prevalence of the CRISPR-Cas systems and their association with antibiotic resistance in one of the most challenging bacterial pathogens, Klebsiella pneumoniae. MATERIALS AND METHODS: A total of 105 K. pneumoniae isolates were collected from various clinical infections. Extended-spectrum ß-lactamases (ESBLs) phenotypically were detected and the presence of ESBL, aminoglycoside-modifying enzymes (AME), and CRISPR-Cas system subtype genes were identified using PCR. Moreover, the diversity of the isolates was determined by enterobacterial repetitive intergenic consensus (ERIC)-PCR. RESULTS: Phenotypically, 41.9% (44/105) of the isolates were found to be ESBL producers. A significant inverse correlation existed between the subtype I-E CRISPR-Cas system's presence and ESBL production in K. pneumoniae isolates. Additionally, the frequency of the ESBL genes blaCTX-M1 (3%), blaCTX-M9 (12.1%), blaSHV (51.5%), and blaTEM (33.3%), as well as some AME genes such as aac(3)-Iva (21.2%) and ant(2'')-Ia (3%) was significantly lower in the isolates with the subtype I-E CRISPR-Cas system in comparison to CRISPR-negative isolates. There was a significant inverse correlation between the presence of ESBL and some AME genes with subtype I-E CRISPR-Cas system. CONCLUSION: The presence of the subtype I-E CRISPR-Cas system was correlated with the antibiotic-resistant gene (ARGs). The isolates with subtype I-E CRISPR-Cas system had a lower frequency of ESBL genes and some AME genes than CRISPR-negative isolates.

Molecular typing of clinical multidrug-resistant Klebsiella pneumoniae isolates.

INTRODUCTION: Klebsiella pneumoniae is an opportunistic pathogen which is an important cause of hospital-acquired and antibiotic resistance infections. Therefore, this study aimed to determine the frequency of resistance to antibiotics, as well as the molecular typing of the associated isolates, and compare multiple-locus VNTR analysis (MLVA) and Enterobacterial Repetitive Intergenic Consensus-Polymerase Chain Reaction (ERIC-PCR) methods to specify the degree to which distinctions can be separated from each other. METHODS AND MATERIALS: One hundred K. pneumoniae isolates were obtained from different sources of infections from patients admitted to hospitals. Antibiotic susceptibility testing was then performed by applying the Kirby-Bauer disk diffusion method. Typing of K. pneumoniae was done by utilizing MLVA and ERIC-PCR methods. RESULTS: Eighty-six multidrug-resistant (MDR) K. pneumoniae isolates were identified, which resistance to ampicillin, trimethoprim/sulfamethoxazole, and ceftriaxone was the most frequent in the considered isolates (100, 93, and 93%, respectively). A total of 50 different antibiotic susceptibility patterns were observed among the MDR K. pneumonia, with the most frequent pattern being resistance to all antibiotics (12.79%) and resistance to all antibiotics except amikacin (10.47%). The isolates were then divided into 37 different MLVA types and seven clonal complexes were obtained from the minimum spanning tree analysis. Finally, the isolates were assigned to 38 different ERIC types. The discriminatory power of MLVA and ERIC methods also showed a value of 0.958, and 0.974. CONCLUSION: Both PCR-typing methods with phenotypic patterns can be useful for the epidemiological typing of K. pneumoniae isolates with the highest performance in discriminating isolates.

A critical review of novel antibiotic resistance prevention approaches with a focus on postbiotics.

Antibiotic resistance is a significant public health issue, causing illnesses that were once easily treatable with antibiotics to develop into dangerous infections, leading to substantial disability and even death. To help fight this growing threat, scientists are developing new methods and techniques that play a crucial role in treating infections and preventing the inappropriate use of antibiotics. These effective therapeutic methods include phage therapies, quorum-sensing inhibitors, immunotherapeutics, predatory bacteria, antimicrobial adjuvants, haemofiltration, nanoantibiotics, microbiota transplantation, plant-derived antimicrobials, RNA therapy, vaccine development, and probiotics. As a result of the activity of probiotics in the intestine, compounds derived from the structure and metabolism of these bacteria are obtained, called postbiotics, which include multiple agents with various therapeutic applications, especially antimicrobial effects, by using different mechanisms. These compounds have been chosen in particular because they don't promote the spread of antibiotic resistance and don't include substances that can increase antibiotic resistance. This manuscript provides an overview of the novel approaches to preventing antibiotic resistance with emphasis on the various postbiotic metabolites derived from the gut beneficial microbes, their activities, recent related progressions in the food and medical fields, as well as concisely giving an insight into the new concept of postbiotics as "hyperpostbiotic".

Interaction Between Altered Gut Microbiota and Sepsis: A Hypothesis or an Authentic Fact?

Sepsis, as an important public health concern, is one of the leading causes of death in hospitals around the world, accounting for 25% of all deaths. Nowadays, several factors contribute to the development of sepsis. The role of the gut microbiota and the response state of the aberrant immune system is dominant. The effect of the human microbiome on health is undeniable, and gut microbiota is even considered a body organ. It is now clear that the alteration in the normal balance of the microbiota (dysbiosis) is associated with a change in the status of immune system responses. Owing to the strong association between the gut microbiota and its metabolites particularly short-chain fatty acids with many illnesses, the gut microbiota has a unique position in the research of microbiologists and even clinicians. This review aimed to analyze studies' results on the association between microbiota and sepsis, with a substantial understanding of their relationship. As a result, an extensive and comprehensive search was conducted on this issue in existing databases.

Evaluation of CD39, CD73, HIF-1α, and their related miRNAs expression in decidua of preeclampsia cases compared to healthy pregnant women.

BACKGROUND: The Preeclampsia (PE) molecular mechanisms are not fully revealed and different biological processes are involved in the pathogenesis of PE. We aimed to evaluate adenosine and hypoxia-related signaling molecules in PE patients in the current study. METHODS: Decidua tissue and peripheral blood samples were taken from 25 healthy pregnant and 25 PE women at delivery time. CD39, CD73, and Hypoxia-inducible factor-alpha (HIF-α) were evaluated in mRNA and protein level using real-time PCR and western blotting techniques, respectively. Also, miR-30a, miR-206, and miR-18a expression were evaluated by real-time PCR. At last, secretion levels of IGF and TGF-ß in the taken serum of blood samples were measured by ELISA. RESULTS: Our results revealed that Expression of CD39 is decreased in PE cases versus healthy controls at mRNA and protein levels (p = 0.0003 for both). CD73 and HIF-α showed an increased level of expression in PE patients at RNA and protein status (p = 0.0157 and p < 0.0001 for protein evaluation of CD73 and HIF-α, respectively). The miRNA-30a (p = 0.0037) and miR-206 (p = 0.0113) showed elevated expression in the decidua of the PE group. The concentration of secreted IGF-1 (p = 0.0002) and TGF-ß (p = 0.0101) in serum samples of PE cases compared to the healthy group were decreased. CONCLUSION: In conclusion, our results showed that aberrant expression of molecules that are involved in ATP catabolism and the hypoxic conditions is observed in PE cases and involved in their hypertension and inflammation could be served as PE prognosis by more confirming in comprehensive future studies. miR-206 and miR-30a play a role by regulating CD39 and CD73 as molecules that are involved in ATP catabolism as well as regulating the production of IGF-1 in the process of hypertension, which is the main feature in patients with preeclampsia. On the other hand, decreased level of miR-18a lead to upregulation of HIF-1a, and the consequence condition of hypoxia increases hypertension and inflammation in these patients.

Postbiotics: A novel strategy in food allergy treatment.

During the last two decades, the prevalence and severity of clinical appearances of food allergy (FA) have a significant rise. FA derives from a breakdown of immune tolerance. In recent year's clinical evidence have shown that the probiotics have significant influences on FA by improving the immune tolerance. Besides, postbiotics due to their unique characteristics (safe profile, more shelf life, resistance to mammalian enzymes and stable to digestive system conditions), may have safety superiority against their parent live cells and as a novel strategy can be applied for improvement immune tolerance and treatment of FA without any undesirable side-effects or human opportunistic infections, particularly in infants and pediatrics.

Synthesis, characterization, and evaluation of curcumin-loaded endodontic reparative material.

Curcumin (CUR) is an ancient therapeutic agent with remarkable antimicrobial and anti-inflammatory properties. The purpose of the current study was to synthesize and evaluate a curcumin-based reparative endodontic material to reduce infection and inflammation besides the induction of mineralization during the healing of the dentin-pulp complex. Poly-ɛ-caprolactone (PCL)/gelatin (Gel)/CUR scaffold was synthesized and assessed by scanning electron microscopy, Fourier transform infrared spectroscopy, and thermo-gravimetric analysis (TGA). Agar diffusion test was performed against E. coli, A. baumannii, P. aeruginosa, S. aureus, E. faecalis, and S. mutans. Moreover, proliferative, antioxidative, anti-inflammatory, and calcification properties of these scaffolds on human dental pulp stem cells (hDPSCs) were evaluated. The results showed that PCL/Gel/CUR scaffold had antibacterial effects. Also, these CUR-based scaffolds had significant inhibitory effects on the expression of tumor necrosis factor α and DCF from inflamed hDPSCs (p < 0.05). Moreover, the induction of mineralization in hDPSCs significantly increased after seeding on CUR-based scaffolds (p < 0.05). Based on these findings, the investigated CUR-loaded material was fabricated successfully and provided an appropriate structure for the attachment and proliferation of hDPSCs. It was found that these scaffolds had antimicrobial, antioxidant, and anti-inflammatory characteristics and could induce mineralization in hDPSCs, which is essential for healing and repairing the injured dentin-pulp complex.

The effects of nanocurcumin on Treg cell responses and treatment of ankylosing spondylitis patients: A randomized, double-blind, placebo-controlled clinical trial.

AIM: Ankylosing spondylitis (AS) is an inflammatory rheumatic disease with increased bone mass in the main sites of inflammation. Regulatory T (Treg) cells have been reported to involve in pathology of AS. This study designed at investigating the effects of nanocurcumin on Treg cell responses in peripheral blood (PB) of AS patients. METHODS: Test group including 12 AS patients received nanocurcumin daily for 4 months and control group including 12 patients received placebo. The frequency of Treg was measured by flow cytometry. The expression levels of FoxP3 and several associated microRNAs (miRNAs; miR-27, miR-17, and miR-146a) and cytokines including Interleukin-10 (IL-10), TGF-ß, and IL-6 were assessed by real-time polymerase chain reaction. Furthermore, enzyme-linked immunosorbent assay was done to determine the secretion levels of cytokines. RESULTS: After treatment with nanocurcumin the frequency of Treg cells in AS patients increased significantly. The RT-PCR data indicated that the expression of miR-17 and miR-27 were significantly decreased following nanocurcumin treatment while miR-146a and FoxP3 were significantly increased. Moreover, nanocurcumin-treated group had high levels of IL-10 and TGF-ß and low levels of IL-6 production than control group. CONCLUSION: The findings suggested that dysregulation of Treg cells in PB influences the AS development and nanocurcumin therapy could regulate the Treg cells, and so could be useful in the treatment of AS and may be other autoimmune diseases. This study is registered with IRCT.ir, number IRCT2017052927520N7.

AdeB efflux pump gene knockdown by mRNA mediated peptide nucleic acid in multidrug resistance Acinetobacter baumannii.

Multidrug-resistant Acinetobacter baumannii isolates cause critical problems in health-care environments. AdeABC is a resistance-nodulation-cell division (RND)-type multidrug efflux pump conferring resistance to clinically essential antibiotics in A. baumannii, such as ciprofloxacin. This study aimed to target adeB gene with antisense peptide nucleic acid (PNA) and investigate its effect on resistance to antibiotics. NCBI database was used to design appropriate PNA to target adeB gene, by connecting PNA to mRNA, the translation of mRNA can be prevented. Three clinical isolates and A. baumannii ATCC 17978 were treated with the designed PNA by electroporation and competence procedure. Minimum Inhibitory concentration (MIC) of ciprofloxacin, colistin, and tetracycline were determined by microbroth dilution method. In addition, the expression level of adeB gene was measured by quantitative real-time PCR (qRT-PCR). Isolates used in this study had mutations in gyrA and parC genes corresponding to resistance to ciprofloxacin. MIC of resistance to ciprofloxacin after treatment with PNA was reduced from 32 µg/ml to16 µg/ml in A. baumannii ATCC 17978 isolate. Susceptibility level of tetracycline, in the 2 clinical isolates was decreased from 64 µg/ml to 32 µg/ml and in the other isolate was reduced from 128 µg/ml to 64 µg/ml. The expression level of adeB gene was decreased in A. baumannii ATCC 17978 (P > 0.01) but not in clinical isolate (P = 0.107). Findings of the present study indicate overexpression of adeB efflux pump has extra effect on resistance to antibiotics in isolates with a defined mechanism of resistance. Antisense technology is a feasible technique to suppress the function of these genes, which may be further exploited to control multidrug-resistant isolates.

Antisense peptide nucleic acids againstftsZ andefaA genes inhibit growth and biofilm formation of Enterococcusfaecalis.

Enterococcus faecalis is one of the important causes of nosocomial infections. Nowadays, increasing prevalence of antibiotic-resistant bacteria and slow progress in recognizing new antimicrobial agents has limited the efficiency of conventional antibiotics, which cause to find novel strategies to overcome bacteria. Therefore, in this study, we aimed to assess the role of efaA gene in the biofilm formation and the role of ftsZ gene in the controlling of bacterial growth by the anti-sense PNAs(Peptide Nucleic Acid).E. faecalis ATCC® 29212™was used for the study of PNAs designed to targeting the start codon section of the ftsZ andefaA genes. PNA attachment to RNA was confirmed by blotting. Electroporation technique was used for the intracellular transfer of anti-ftsZ PNAs. The spot-plating method was used to the assessment of alteration in bacterial growth. Biofilm formation assay and real-time PCR were used for detection of biofilm inhibitory effect of cell penetrating peptide (CPP) conjugated to anti-efaA PNAs.ByftsZ PNAs treatment, no growth was seen from the strain in agar by a spot plating method and the inhibition zone of anti-ftsZ PNAs was not seen. PNAs against the efaA gene decreased by 95% the expression of the efaA gene and biofilm formation. In addition, the(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide) MTT assay showed no toxicity on MCF7 cells for both of anti-ftsZand anti-efaA PNAs.This study used new genetic and molecular tools to inhibit pathogenicity and infection by E. faecalis. In this study, we suggested that efaA gene plays a critical role in the biofilm formation and anti-efaA PNAs could decrease the formation of biofilm, as well as, anti-ftsZ PNAs could eliminate bacterial growth.

Non-alcoholic fatty liver diseases: from role of gut microbiota to microbial-based therapies.

Non-alcoholic fatty liver disease (NAFLD) is the well-known disease of the liver in adults and children throughout the world. The main manifestations related to NAFLD are an unusual storage of lipid in hepatocytes (hepatic steatosis) and progression of inflammation for non-alcoholic steatohepatitis (NASH). NAFLD is described as a multifactorial complication due to the genetic predisposition, metabolic functions, inflammatory, gut microbiota (GM), and environmental factors. The GM dysregulation among these factors is correlated to NAFLD development. In recent decades, advanced microbial profiling methods are continuing to shed light on the nature of the changes in the GM caused by NASH and NAFLD. In the current review, we aim to perform a literature review in different library databases and electronic searches (Science Direct, PubMed, and Google Scholar) which were randomly obtained. This will be done in order to provide an overview of the relation between GM and NAFLD, and the role of prebiotics, probiotics, and fecal microbiota transplantation (FMT), as potential therapeutic challenges for NAFLD.

Comparative study on the microbial quality in the swimming pools disinfected by the ozone-chlorine and chlorine processes in Tabriz, Iran.

Applying a desirable disinfestation process is necessary to control the pathogenic microorganisms in the swimming pools and prevent both dermal and intestinal effects. Therefore, the present study was conducted to compare the bacterial community and diversity in the two swimming pools disinfected by the chlorine and ozone (O3)-chlorine processes. A total of 24 samples were taken from the two swimming pools in three distinct seasons to analyze the bacterial and physico-chemical indicators. Culture and molecular methods were used to evaluate the microbial quality. Two sets of sample taken from the pools with the maximum swimmer load in the summer were investigated by the next-generation sequencing (NGS) technique. In total, 410 and 406 bacterial species were identified in the chlorine- and ozone-chlorine-disinfected pools, respectively. Among the eight dominant bacterial species in each swimming pool, Pseudomonas alcaliphila, Pseudomonas stutzeri, and Pseudomonas acnes were common species between the two studied pools. Oleomonas sagaranensis (350 reads/18593), Staphylococcus caprae (302 reads /18593), and Anaerococcus octavius (110 reads/18593) were among the dominant bacteria in the chlorine-disinfected pool. Bacterial diversity was lower in the ozone-chlorine-disinfected pool than the other one, and the highest bacterial sequencing belonged to the genus Pseudomonas (85.79%). Results showed that water quality of in O3-chlorine-disinfected pool was more desirable than the chlorine-disinfected pool. Molecular methods along with conventional culture methods would be advantageous for microbial assessment in the swimming pools.

The roles of signaling pathways in liver repair and regeneration.

The liver has remarkable regeneration potency that restores liver mass and sustains body hemostasis. Liver regeneration through signaling pathways following resection or moderate damages are well studied. Various cell signaling, growth factors, cytokines, receptors, and cell types implicated in liver regeneration undergo controlled hypertrophy and proliferation. Some aspects of liver regeneration have been discovered and many investigations have been carried out to identify its mechanisms. However, for optimizing liver regeneration more should be understood about mechanisms that control the growth of hepatocytes and other liver cell types in adults. The current paper deals with the possible applicability of liver regeneration signaling pathways as a target for therapeutic approaches and preventing various liver damages. Furthermore, the latest findings of spectrum-specific signaling pathway mechanisms that underlie liver regeneration are briefly described.

Evidences from a Systematic Review and Meta-Analysis Unveil the Role of MiRNA Polymorphisms in the Predisposition to Female Neoplasms.

Breast (BCa) and gynecological (GCa) cancers constitute a group of female neoplasms that has a worldwide significant contribution to cancer morbidity and mortality. Evidence suggests that polymorphisms influencing miRNA function can provide useful information towards predicting the risk of female neoplasms. Inconsistent findings in the literature should be detected and resolved to facilitate the genetic screening of miRNA polymorphisms, even during childhood or adolescence, and their use as predictors of future malignancies. This study represents a comprehensive systematic review and meta-analysis of the association between miRNA polymorphisms and the risk of female neoplasms. Meta-analysis was performed by pooling odds-ratios (ORs) and generalized ORs while using a random-effects model for 15 miRNA polymorphisms. The results suggest that miR-146a rs2910164 is implicated in the susceptibility to GCa. Moreover, miR-196a2 rs11614913-T had a moderate protective effect against female neoplasms, especially GCa, in Asians but not in Caucasians. MiR-27a rs895819-G might pose a protective effect against BCa among Caucasians. MiR-499 rs3746444-C may slightly increase the risk of female neoplasms, especially BCa. MiR-124 rs531564-G may be associated with a lower risk of female neoplasms. The current evidences do not support the association of the remaining polymorphisms and the risk of female neoplasms.

miRNA Polymorphisms and Risk of Cardio-Cerebrovascular Diseases: A Systematic Review and Meta-Analysis.

Recently extensive focus has been concentrated on the role of miRNAs in the initiation and progression of cardio-cerebrovascular diseases (CCDs) which constitute a range of conditions including cardiovascular diseases (CVDs, especially coronary artery disease (CAD)), congenital heart disease (CHD) and cerebrovascular diseases (CBVDs, especially the ischemic stroke (IS)). An increasing number of studies are evaluating the association between different miRNA polymorphisms and risk of CCDs, but results have been inconclusive. This study represents a comprehensive systematic review and meta-analysis of the association between miRNA polymorphisms and risk of CCDs. PubMed, Embase, Scopus, and Web of Science were queried to identify eligible articles. Odds ratios and 95% confidence intervals were used to assess the association of miRNA polymorphisms with CCD susceptibility. A total of 51 eligible articles evaluating the association of 31 miRNA polymorphisms were identified. Meta-analysis was performed for six miRNA polymorphisms. miR-146a rs2910164 (30 studies: 13,186 cases/14,497 controls), miR-149 rs2292832 (Nine studies: 4116 cases/3511 controls), miR-149 rs71428439 (Three studies: 1556 cases/1567 controls), miR-196a2 rs11614913 (20 studies: 10,144 cases/10,433 controls), miR-218 rs11134527 (Three studies: 2,322 cases/2,754 controls) were not associated with overall CCD. miR-499 rs3746444 was associated with CCD (20 studies: 9564 cases/8876 controls). In the subgroups, rs2910164 and rs3746444 were only associated with CVDs, especially CAD. In conclusion, the results support the existence of a role for miR-146a rs2910164 and miR-499 rs3746444 in determining susceptibility to CCDs, especially CAD.

Warning: spread of NDM-1 in two border towns of Iran.

NDM-1 producing gram-negative bacteria can be resistant to every beta-lactam antibiotic, including carbapenem which is one of the last-lines of antibiotic therapy against multi-drug resistant bacteria. This study aimed to detect the metallo-beta-lactamase in the isolated gram-negative bacteria of the Iranian clinical specimens collected from two major cities in Iran. In this cross sectional study 171 Acinetobacter baumannii, 120 Enterobacter spp. and 145 Klebsiella pneumoniae isolated from clinical specimens of two training hospitals in Tabriz and Mashhad were evaluated. Carbapenem resistant screening was performed according to CLSI guide line. The antibiotic susceptibility testing was prepared for carbapenem resistant strains. Then, the metallo-beta- lactamase genes detection was also carried out by PCR assay and confirmed by sequencing. Sixty-eight, 12 and 22 carbapenem resistant Acinetobacter baumannii, Klebsiella pneumoniae and Enterobacter spp. were respectively confirmed, respectively. blaVIM in 9% and blaNDM-1  in 4% of isolated A. baumannii were observed. blaNDM-1 was also detected in 18% and 25% of K. pneumoniae and Enterobacter spp. isolates, respectively. This is the first report of NDM-1 producer A. baumannii and Enterobacter pp. in Iran. NDM-1 producing gram-negative bacteria can be resistant to all beta-lactam antibiotics and cause complicated challenges in health care systems.

Frequency of Smear-Negative Tuberculosis in Northwest Iran.

BACKGROUND: Microscopic smear examination is the most common test in tuberculosis (TB) detection. It is, however, not strong enough to identify TB in the majority of afflicted individuals; thus, a significant number of TB patients are smear negative and capable of transmitting the infection. The aim of this study was to evaluate the rate of smear-negative TB in northwest Iran. METHODS: In this cross-sectional study, 329 TB-confirmed patients were evaluated through culture up to March 1, 2015, in northwest Iran. The demographic and clinical features of the smear-negative and smear-positive TB patients were compared. The χ2 test was used to compare the frequency of the variables. All the statistical analyses were conducted using SPSS, version 16 (Chicago, IL, USA). RESULTS: Seventy-five cases were smear negative and 254 were smear positive. Smokers, asthmatics, and extra-pulmonary TB patients were primarily among the smear-negative cases. The rate of mortality was also relatively higher among the smear-negative TB patients. CONCLUSION: Totally, 22.8% of the TB cases in northwest Iran were smear negative, with a relatively higher rate of mortality than those with positive smears. A delay in these patients' return to TB diagnosis and treatment centers increases the chance of transmission to others. This is a very sensitive issue in centers where there is no equipment for TB cultivation. Thus, it is essential to equip centers without TB cultivation facilities and to use appropriate diagnostic techniques in centers with those facilities to help rapidly detect smear-negative cases.

Linezolid: a promising option in the treatment of Gram-positives.

Linezolid, an oxazolidinone antimicrobial agent that acts by inhibiting protein synthesis in a unique fashion, is used in the treatment of community-acquired pneumonia, skin and soft-tissue infections and other infections caused by Gram-positive bacteria including VRE and methicillin-resistant staphylococci. Currently, linezolid resistance among these pathogens remains low, commonly <1.0%, although the prevalence of antibiotic resistance is increasing in many countries. Therefore, the development of resistance by clinical isolates should prompt increased attention of clinical laboratories to routinely perform linezolid susceptibility testing for this important agent and should be taken into account when considering its therapeutic use. Considering the importance of linezolid in the treatment of infections caused by Gram-positive bacteria, this review was undertaken to optimize the clinical use of this antibiotic.

Strong antimicrobial activity of Hypericum perforatum L. against oral isolates of Lactobacillus spp.

Lactobacillus spp. are one of the first microorganisms involved in the development of dental caries in the first years of life of the child. The purpose of this study was to investigate the antibacterial effect of alcoholic extract of hypericin against strains of Lactobacillus spp. and determine its related MIC (minimum inhibitory concentration); and cytotoxic effect against gingival fibroblasts. Antimicrobial activity and MIC were evaluated using micro broth dilution method based on CLSI (clinical and laboratory standards institute) protocols. Determination of cytotoxicity was done by using MTT assay protocol on gingival fibroblast cells at 24, 48 and 72 hours after adding different concentrations of alcoholic extract of hypericin. Hypericin extract had an antimicrobial effect on lactobacillus spp., and its MIC was determined to be 0.625µg/ml . The IC50 value after 24, 48 and 72 hours was obtained as 0.89µg/ml, 0.7µg/ml and 0.604µg/ml, respectively. Hypericin extract MIC for L.acidophilus spp. was 0.625µg/ml and given that, MIC was less than IC50. This concentration does not have toxic effects on gingival fibroblast cells. The results of this study indicate that hypericin extract was able to eliminate acid producing strains in the mouth and can be evaluated as a suitable and safe substitute for mouthwashes and oral disinfectants.

CRISPR-like sequences association with antibiotic resistance and biofilm formation in Helicobacter pylori clinical isolates.

Role of clustered regularly interspaced short palindromic repeats (CRISPR)-like sequences in antibiotic resistance and biofilm formation isn't clear. This study investigated association of CRISPR-like sequences with antibiotic resistance and biofilm formation in H. pylori isolates. Thirty-six of H. pylori isolates were studied for existence of CRISPR-like sequences using PCR method and their correlation with biofilm formation and antibiotic resistance. Microtiter-plate technique was utilized for investigating antibiotic resistance profile of isolates against amoxicillin, tetracycline, metronidazole and clarithromycin. Biofilm formation of isolates was analyzed by microtiter-plate-based-method. Out of 23 CRISPR-like positive isolates, 19 had ability of biofilm formation and 7 of 13 CRISPR-like negative isolates were able to form biofilm (Pvalue = 0.445). In CRISPR-like positive isolates, 11 (48%), 18 (78%), 18 (78%) and 23 (100%) were resistant to amoxicillin, tetracycline, metronidazole and clarithromycin, respectively. Since CRISPR-like sequences have role in antibiotic resistance, may be applied as genetic markers of antibiotic resistance. But there was no substantial correlation between biofilm formation and existence of CRISPR-like sequences. These results indicate possible importance of CRISPR-like sequences on acquisition of resistance to antibiotics in this bacterium.