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Background: Most of the population in the different areas of world is affected by bacterial infections responsible for dental caries. Due to the importance of traditional medicines derived from herbs used for dental problems, this study investigated in vitro antibacterial activity of Mentha longifolia essential oil from Ardabil, Iran, on Streptococcus mutans, Lactobacillus rhamnosus and Actinomyces viscosus,bacteria that cause tooth decay. Materials and Methods: The volatile oil of Mentha longifolia leaves was extracted by hydrodistillation method using a Clevenger-type apparatus  and analyzed by GC and GC/MS system.The antibacterial activity was evaluated by the disk diffusion susceptibility in dilutions of 62.5, 125, 250, 500, 1000 and 2000μg/μl and broth macrodilution test methods. Results: The oil was particularly rich in Pulegone (31.78%), 1,8-cineole (15.99%), menthoforan (11.25%), cis-isopulegon (10.5%) and paramenth-3-n-8-l (6.85%). The medicinal plant essential oil could prevent the growth of the bacteria, and the rates of MIC and MBC of native pennyroyal essential oil on Streptococcus mutans, Lactobacillus rhamnosus and Actinomyces viscosus were 110, 165, 80, 120, 450 and 650μg/μl, respectively. The maximum inhibition zone diameter was about 12.2, 27.2 and 4.8 mm, for Streptococcus mutans, Lactobacillus rhamnosus and Actinomyces viscosus respectively, at the concentration of 500μgμl^-1. Conclusion: In this work, the essential oil of medicinal plant containing effective ingredients could prevent the growth of bacteria and may be used as an affordable and available source for medicinal purposes.

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  Abstract Background: Streptococcus mutans in the oral cavities sable to produce mutacin (bacteriocin-like substances) with antibiotic properties. The aim of this study was to investigate the frequency and expression of genes encoding mutacins typeI, II, III and IV and also two of 8 genes in a cluster encoding the putative bacteriocins, the designated bsm 283, bsm 299, bsm 423, bsm 1889c, bsm 1892c, bsm 1896, bsm 1906c and bsm 1914, were also screened by PCR and specific primers for each type of mutacin biosynthesis gene and then mutacin activity against the indicator strains determined. Methods : In this study, dental clinic samples were collocated; Streptococcus mutans was detected using biochemical tests and molecular methods (PCR). Frequency of mutacin biosynthesis genes types I, II, III and IV, bsm299 and bsm1899 were measured by PCR, using specific primers for each type of mutacin biosynthesis gene. Furthermore, the antimicrobial spectra of Streptococcus mutans isolates against other indicators, including Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Salmonella typhi, Pseudomonas, Escherichia coli were evaluated using well diffusion, disk diffusion and the minimal inhibitory concentrations (MICs) methods. Results : Out of 56 samples collected from patients referred to Milad Hospital dental clinic on October 2011 and three private dental clinics on November 2011, 24 strains of Streptococcus mutans produced mutacins. 67.52% of the strains had a wide antimicrobial spectrum and 37.5% of 67.5% had a high frequency of genes with more inhibitory activity against, Staphylococcus epidermidis, Staphylococcus aureus and Enterococcus faecalis respectively that are more related to putative bacteriocins. The expression frequency of the bsm gene (putative bacteriocins) was higher than that of the characterized mutacins types (I–IV). The lowest dilution rate mutacin was found against Staphylococcus epidermidis (0.0625 unit/mL). Conclusion : These findings suggested that all putative bacteriocins may represent a large repertoire of inhibitory substances produced by Streptococcus mutans. Therefore, the high diversity of mutacin-producing phenotypes, associated with high frequency of expression of the biosynthesis genes screened and wide antimicrobial activity against Staphylococcus epidermidis could be used as safe antimicrobial agents in treatment of superficial infections such as, removing the pimple caused by Staphylococcus epidermidis.

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Background: Group B streptococcus (GBS) is the major cause of serious life threatening infections in neonates, pregnant women, and other adults with underlying diseases. Capsular polysaccharide typing is a significant way for epidemiological studies of GBS, the pathogenesis, and other studies associated with GBS infections including surveillance programs and vaccine development in future. Molecular serotyping (MS) methods offer more accurate and reliable typing of bacteria. The aim of current study was to differentiate genotypes of clinical GBS isolates based on PCR assay to acquire information about the distribution of GBS types in Hamadan, Iran.
Materials and Methods: A total of 62 clinical GBS strains including vaginal swabs, urine cultures, and blood culture isolates were examined for genotyping using multiplex PCR assay.
Results:Among the 62 GBS isolates examined, all capsular types, except VI, VII, and VIII, were found. Type III was the predominant type with 35 isolates (56.5%), followed by Type V with 11 isolates (17.7%), Type II with 7 isolates (11.3%), Type Ia with 5 isolates (8.1%), and Types Ib and IV with similar prevalence of 2 isolates (3.2%) for each type.
Conclusion: The results of the current study demonstrated that Type III is the predominant type in Hamadan, followed by Types V, II, Ia, Ib, and IV, respectively. Using MS method leads to accurate, sensitive, specific, and fast typing of GBS isolates. The advantages of MS method allow it to analyze various populations and to examine invasive and colonizing isolates in extensive epidemiological studies and surveillance activities. In fact, MS will facilitate the proper formulation of candidate GBS vaccines.

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Background: Streptococcus agalactiae, also known as Group B Streptococcus (GBS) is a commensal organism in the urogenital tract and rectum in approximately 25% of the healthy adult female population. The bacterium is the leading cause of bacterial meningitis, pneumonia, and sepsis in human infants.
Materials and Methods: Our study was performed over a three - month period from April to June 2014. Midstream specimens of urine were collected from outpatients suspected of having a bacterial urinary tract infection, which had not received any antibiotics. Group B Streptococci isolates were confirmed by typical colony morphology and identified by differential tests. Antibiotic susceptibility testing was carried out by disk diffusion method on Mueller Hinton agar (Merck, Germany) based on (CLSI) Guidelines 2012.
Results: GBS strains were isolated from 264 (21.1%) cases (out of 1249 positive bacterial urine cultures). The higher prevalence was recorded in the 15-44 and 45-64 age groups. Antibiotic susceptibility tests revealed that vancomycin, penicillin, and linezolid had the lowest, and tetracycline had the highest resistance rate.
Conclusion: In conclusion, the results of the present study confirm the universal susceptibility of GBS strains to the penicillin family and assert the use of penicillin or ampicillin as the first drug of choice for treatment and prophylaxis against GBS infections. However, it is important to perform antibiotic susceptibility testing whenever penicillin could not be prescribed.

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Aims: Streptococcus mutans (S. mutans) is part of human oral cavity microbiome and is known to be responsible of dental caries. The aim of this study was to evaluate the inhibitory effects of Punica granatum, Ricinus communis, and Allium sativum extracts on biofilm formation caused by S. mutans.
Materials and Methods: In this experimental study, the biofilm formation was carried out by broth dilution method with glucose -supplemented Tryptic Soy Agar (TSB) in 96-well microtiter plates. Seven serial dilutions from the aqueous extracts of the Punica granatum, Ricinus communis, and Allium sativum were prepared. Then, a suspension of S. mutans was added to the wells. The anti-biofilm effects of the extracts and turbidity were measured by an ELISA reader apparatus at OD₄₉₂nm. Experiments were completed in triplicate.
Findings: Ricinus communis was more active on S. mutans than other extracts. In comparison with others, the mean OD obtained in the presence of a concentration of 50mg of the plant extract (OD=0.083) was close to the negative control (OD=0.068). This plant was effective in higher concentrations (50, 25, 12.5 and 6.25mg/ml). Allium sativum extract has a moderate effect on S. mutans. The lowest activity belonged to Punica granatum extract.
Conclusion: The extract of Ricinus communis has strong anti-biofilm activity against Streptococcus mutans, when compared to other extracts, Allium sativum extract show moderate activity on the biofilm formation. Aqueous extract of Punica granatum peel isn’t very effective on S. mutans.

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.  The bacteriostatic and bactericidal activity of the ethanol extract of Kelussia odoratissima and chicory, Cichorium intybus L., against Streptococcus iniae and Lactococcus garvieae isolated from rainbow trout was investigated. Antibacterial efficiency of the plants was examined using agar well diffusion method and minimum inhibitory concentration. The MIC of the ethanol extract of K. odoratissima for S. iniae and L. garvieae were found to be 100 and 50 mg/ml, respectively and the MIC of the ethanol extract of C. intybus L for S. iniae was 50 mg/ml. Chicory didn’t have any inhibitory effect on L. garvieae.

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Aim: Group A Streptococcus (GAS) is the causative agent of several invasive and non-invasive diseases. Several virulence factors contribute to the pathogenesis of GAS, such as M protein, hemolysins, and extracellular enzymes. Due to the improper use of antibiotics, the resistance of these microorganisms to antibiotics is increasing. Bacteriocins as an alternative to antibiotics are of great importance. In this study, the effect of antimicrobial Bacteriocin nisin was investigated on the expression of smeZ gene.
Materials & Methods: Samples were taken from the site of infection on the skin surface of the patients at the dermatology clinics of Tehran public hospitals. The specimen was immediately transferred to the primary culture medium or basal medium. Chromosomal DNA extraction was performed using the standard method for the extraction of Streptococcus pyogenes genomes. Multiplex PCR was performed to identify the presence of smeZ, speI, and speH genes in the isolates. The expression of smeZ gene was evaluated using the real-time PCR technique.
Findings: The frequencies of smeZ, speI, and speH genes in 12 S. pyogenes isolates were 25, 8.3, and 8.3%, respectively. The fold change rate for smeZ gene was -1.209, indicating that this gene was decreased 1.209 folds in the treated group compared to the untreated group.
Conclusion: Bacteriocin not only reduces the number of pathogens but may also affect the metabolism of the bacteria by producing toxins. The use of new antimicrobial agents in place of previous drugs for psoriasis patients could be considered as a way to treat the disease more effectively in the future.
 

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Background: Bacterial meningitis is a devastating infection associated with significant morbidity and mortality rate among neonates and young children. Early identification and treatment of the causative agents of meningitis is crucial due to high fatality rate in untreated cases. The present study aimed to investigate the common bacterial etiology and occurrence of antimicrobial resistance in patients suspected to meningitis in southwestern Iran.
Materials & Methods: This retrospective cross-sectional study was conducted during a five-year period from January 2011 to January 2016 at two major hospitals in southwestern Iran. CSF samples were aseptically collected in BACTECTM, and conventional methods were used for the bacteria isolation and identification. Antimicrobial susceptibility tests were done using disk diffusion and E-test methods.
Findings: Out of 89 CSF samples collected from children under 17 years, the number of culture positive specimens was 21 (23.6%). The highest number of culture positive cases was observed in patients younger than 5 years (57.1 %). The most frequent pathogens were Streptococcus pneumonia (N = 10, 47.6%), followed by Haemophilus spp. (N = 3, 14.3%), and Neisseria meningitidis (N = 3, 14.3%). Antibacterial susceptibility testing results showed that S. pneumoniae isolates were mostly susceptible to vancomycin and chloramphenicol. Moreover, among N. meningitides and Haemophilus isolates, the most effective in vitro drug was ceftriaxone (100%).
Conclusions: These results showed the promising activity of several locally available antibiotics against S. pneumoniae, Haemophilus spp. and N. meningitides, as the most common causative agents of bacterial meningitis in Iranian children. Therefore, such regional studies help prevent and control the burden of infections.

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Backgrounds: Group B Streptococcus (GBS) is an important opportunistic bacterial pathogen that could cause serious infections, especially in neonates, adults, and the elderly. In GBS isolates, a macrolide resistance phenotype that confers constitutive resistance to macrolide-lincosamide-streptogramin B antibiotics (cMLSB phenotype) has become a global concern. On the other hand, little is known about the genetic relatedness and diversity of GBS isolates isolated from various patients in Iran. Hence, this study aimed to determine the genetic relatedness and molecular typing of cMLSB-GBS isolates using enterobacterial repetitive intergenic consensus-PCR (ERIC- PCR) technique.
Materials & Methods: A total of 100 GBS isolates were collected from patients with urinary tract infections (UTI).  Among them, 52 erythromycin-resistant GBS isolates were selected, and double-disc diffusion (D-zone) technique was applied to determine the MLSB phenotype among the isolates based on CLSI criteria. Then the genetic relatedness of MLSB-GBS isolates was assessed using ERIC-PCR fingerprinting method.
Findings: Among 52 erythromycin-resistant GBS isolates, 38 isolates were identified with cMLSB phenotype, nine isolates with M phenotype, and five isolates with iMLSB phenotype. The analysis of ERIC-PCR patterns revealed eight different ERIC types that were divided into seven clusters (A-G) and one single type. Also, four isolates were non-typeable. ERIC type A/ serotype Ib was the most prevalent clone among the isolates.
Conclusion: The current study findings showed a high level of diversity and multiclonal spread of the cMLSB phenotype in Isfahan. ERIC type A/ serotype Ib is the predominant clone circulating among erythromycin-resistant GBS strains.

 

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The aquatic zoonotic bacterial Streptococcus iniae represents a threat to the worldwide aquaculture industry. This study was carried out to evaluate the antibacterial activity Cuminum cyminum essential oil and nisin for control of S.iniae in fillets of Rainbow trout (Oncorhynchus mykiss) in 4 Cº on basis hurdle technology between 2012 and 2013.The effect of different concentrations of nisin (0, 0.25 and 0.75 µg/ml) and Cuminum cyminum (0, 0.005, 0.135 and 0.405 %) were conducted on growth of S.iniae GQ850377 for 15 days. The results showed that growth of bacterial delayed in samples treated with nisin and essential oil singly to 9 days and together to 3 days. Samples treated with essential oil showed a significant decrease on the growth of the bacteria compared with nisin and control sample (P<0.05). No significant different was observed on the growth of S.iniae in samples treated with higher concentrations of C.cyminum (0.135 and 0.405 %) (p>0.05), but different concentrations of nisin was statistically significant (p<0.05). Synergistic effects were observed at concentration of 0.405% C.cyminum and 0.75 µg/mL nisin.  

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There is a global interest to study lactic acid bacteria (LAB) of artisanal fermented products like yoghurt for improving or replacing current strains used in commercial starter cultures. In this work, five traditional yoghurt samples were collected from different areas of Khorasan-e-Razavi. Grouping and identification of isolates were carried out on the basis of physiological and biochemical tests (non-molecular),as well as ARDRA technique and sequencing (molecular methods). Totally, 71 isolates including 33 Streptococcus thermophilus, 30 Lactobacillus delbrueckii (subsp. Bulgaricus and lactis), were identified as dominant strains in all yoghurt samples. Also 8 other isolates belonging to Lactobacillus helveticus, Pediococcus pentosaceus and Weissella cibaria were observed. Results of this research show the diversity of LAB population in collected samples.

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Folate is a term used for a set of compounds with similar biological activities. Folate (polyglutamates) naturally contains all forms of vitamins in this family. In other words, folic acid is a form of folate that is oxidized, this compound is stable and can be absorbed by humans (monoglutamate)[1]. There are several methods for measuring folate, but due to the fact that in this study, the production of extracellular folate (Quatrofolate) was examined, so the microbial assay method was used as the main method. Lactobacillus. Rhamnosus (ATCC7469), which is used as a sensing organism. [2,3] This method can also measure all forms of folate. In this study, 47 medical strains isolated from traditional dairy products were Special Khorasan. traditional yogurt (12 strains of Streptococcus.thermophilus and 15 strains of Lactobacillus delbrueckii subsp. Bulgaricus, 13 strains of Lactobacillus delbrueckii subsp. Lactis, 3 strains of Lactobacillus helveticus) were studied. The results of this evaluation showed that both strains (25 and 26) of Lactobacillus delbrueckii subsp. Bulgaricus produced significant high folate concentrations (133.23 μg / mL and 102.34 μg / mL), as well as K73 strain of Streptococcus.thermophilus, strain 73 from the strains of  Lactobacillus delbrueckii subsp. Lactis and strain No.87 from the three strains of Lactobacillus helveticus (90.29 μg / mL, μg / mL39.71, μg / mL 17.94), were also able to produce high amounts of quatrofolate. According to this study, it was found that the examined previously isolated strains have a potential ability to produce extracellular folate, and the microbial assay method for measuring a sensitive vitamin such as folate in all its forms is considered an efficient and accurate method.
 

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The aim of the current research was microencapsulation of Streptococcus thermophilus and Lactobacillus bulgaricus bacteria by coacervation complex method and sodium caseinate and pectin coatings. Sodium caseinate and pectin have electrostatic attraction together at pH=4 and form a complex. Using a scanning electron microscope, the morphology of coacervates was investigated. The properties of pectin and sodium caseinate complexes were investigated by infrared spectrometry tests and measuring the size and distribution of particles. Physicochemical characteristics such as water absorption, pH and acidity and sensory characteristics were also investigated. The results showed that the efficiency of microencapsulation of bacteria by coacervation method was 66.6%. The particle size was 1.565 micrometers and the zeta potential was reported as -16 mV. Electron microscope images showed spherical coacervate without holes and wrinkles on the surface. The results of infrared spectroscopy also showed the creation of electrostatic interactions between pectin and sodium caseinate. Also, microencapsulation of bacteria caused a significant change (p>0.05) in pH (4.6 ± 0.091) and yogurt acidity (1.1 ± 0.03) compared to pH (4.6 ± 0.1). And the acidity of yogurt (0.8±0.01) produced with free bacteria did not. The water content of yogurts produced with microencapsulated bacteria (40±1.1) was reduced compared to yogurts produced with free bacteria (45±0.9) (p<0.05). Bacterial encapsulation has a negative effect on color sensory characteristics. It did not have the smell and taste of the produced yogurts (p>0/05), but a significant difference was observed in the texture of the yogurts produced with microencapsulated bacteria compared to the yogurts produced with free bacteria (p<0/05).