جستجوی مقالات مرتبط با کلیدواژه « streptococcus » در نشریات گروه « پزشکی »

Nosocomial infections have increased among patients admitted to the intensive care unit (ICU).

This study investigated the microbiota pattern of the respiratory system in hospitalized patients with treatment-resistant respiratory infections compared to those without treatment-resistant respiratory infections.

This case-control study utilized sputum samples from hospital-acquired infection (HAI) and non-HAI (NHAI) patients over 52 years old hospitalized in the ICU. Identification and determination of the drug sensitivity of the bacteria responsible for treatment-resistant respiratory infections were made by culture method in selective and differential media and VITEK 2 device. Finally, quantitative polymerase chain reaction (qPCR) was used to analyze the microbiota of the respiratory system.

Excessive prescription of antibiotics, long hospitalization, and history of surgery were important risk factors for nosocomial infections. The study of antibiotic resistance of pathogens causing hospital infections indicated their high resistance to most common antibiotics. Also, nosocomial infections led to a change in lung microbiota in HAI patients. The frequencies of Streptococcus pyogenes, S. pneumoniae, and Haemophilus influenzae were higher in patients with treatment-resistant respiratory infection (P < 0.05), but the frequency of Neisseria spp. was higher in patients without treatment-resistant respiratory infection (P < 0.05).

The pathogens responsible for nosocomial infections had acquired resistance to a wide range of antibiotics, leading to changes in their respiratory microbiota. 

 Early childhood caries is one of the most common chronic diseases in children, affecting both oral and general health. Oral microorganisms are the most important causative agents associated with dental caries in children. The aim of this study was to compare the antimicrobial activity of common Iranian and non-Iranian children's toothpaste on the growth of four standard bacteria strains, including Streptococcus mutans, Streptococcus sanguinis, Lactobacillus acidophilus, and Enterococcus faecalis.

 In this study, six types of the most common Iranian and non-Iranian children toothpaste produced by different companies were prepared. Different concentrations of toothpaste were prepared according to the Clinical and Laboratory Standards Institute (CLSI) standard. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of Iranian and non-Iranian children's toothpaste were measured by the microbroth dilution method at ten different concentrations.

For the S. mutans bacteria, the lowest MIC was found in Misswake, Vi-One, and 2080 toothpaste. In the case of S. sanguinis and L. acidophilus bacteria, the lowest MIC was related to Frice toothpaste, and for E. faecalis bacteria, the lowest MICs were found for Misswake and 2080 toothpaste. Mann-Whitney U test also revealed that the inhibitory and bactericidal activities of Iranian children's toothpaste on the studied bacteria were not significantly different from those of non-Iranian children's toothpaste.

 In general, the antimicrobial activity of Iranian children's toothpaste was higher than non-that of Iranian samples. In addition, the MIC of 2080 and Frice toothpaste in the four bacteria examined was lower than in other used toothpaste. To prevent early tooth decay in children use of these two kinds of toothpaste is recommended.

Streptococcus pseudopneumoniae is a member of viridans streptococci. It is non-capsulated, bile insoluble and optochin susceptible in ambient air but resistant in 5% CO2. This study aimed to isolate S. pseudopneumoniae from sputum specimens of patients admitted to Chest Department and Chest ICU of Assiut University hospitals, differentiate it from Streptococcus pneumoniae in addition, to evaluate the prevalence of Streptococcus pseudopneumoniae in clinical isolates by phenotypic and genotypic methods, to subject the isolates to antimicrobial susceptibility testing using agar disc diffusion method.

Isolation of Streptococcus pseudopneumoniae from sputum sample and doing phenotypic test (optochin susceptibility test,bile susceptibility test and antimicrobial susceptibility test) and genotypic test by polymerase chain reaction (PCR) for five genes: CpsA, LytA, AliB-like ORF2, 16S rRNA and Spn9802 genes.

Twenty isolates of S. pseudopneumoniae were diagnosed phenotypically by optochin susceptibility and bile solubility tests followed by genotypic characterization by polymerase chain reaction (PCR) for five genes: CpsA, LytA, AliB-like ORF2, 16S rRNA and Spn9802 genes. The prevalence of S. pseudopneumoniae among studied patients was 10% (20/200).

The pure growth of S. pseudopneumoniae from sputum samples together with the great percentage of antibiotic resistance should raise attention to the clinical importance of this organism.

In cystic fibrosis patients, the mucus is an excellent place for opportunistic bacteria and pathogens to cover. Chronic infections of upper and lower airways play a critical role in the mortality of cystic fibrosis. This study aimed to introduce the microbiota profiles in patients with cystic fibrosis.

In this study, a comprehensive literature search was done for studies on upper and lower airway microbiota in cystic fibrosis patients. International and national databases were searched for the following MeSH words: microbiota, microbiome, upper airway, lower airway, cystic fibrosis, cystic fibrosis, upper airway microbiome, lower airway microbiome, microbiome pattern in cystic fibrosis, microbiome pattern in cystic fibrosis, upper airway microbiota, lower airway microbiota, and microbiota pattern.

Streptococcus spp. are in significantly higher relative abundance in infants and children with cystic fibrosis; however, Pseudomonas spp. are in higher relative abundance in adults with cystic fibrosis. Molecular diagnostic techniques can be remarkably accurate in detecting microbial strains.

For the detection and isolation of most bacterial species, independent-culture methods in addition to the standard culture method are recommended, and sampling should include both upper and lower airways.

This study aimed to compare the colonization of Enterococcus faecalis (E. faecalis), Escherichia coli (E. coli), Streptococcus mutans (S. mutans) and Staphylococcus aureus (S. aureus) isolated from the oral cavity on different suture materials used in oral implantology.

Patients scheduled for implant surgery were included in this study. After flap approximation, the surgical site was sutured using silk, nylon, polyglactin 910 (Vicryl®) and triclosan-coated polyglactin 910 (Vicryl® Plus) sutures in a randomized order. Seven days after surgery, the sutures were removed and incubated in bile esculin agar (for E. faecalis), MacConkey agar (for E. coli), mitis salivarius agar (for S. mutans), and mannitol salt agar (for S. aureus) at 37°C for 24 h. The colonies were then counted. Data were analyzed using the Kruskal-Wallis and Mann-Whitney U tests.

Vicryl® sutures showed the highest accumulation of E. faecalis, followed by Vicryl® Plus, nylon, and silk. There was no significant difference between nylon and silk (P=0.5) or between Vicryl® and Vicryl® Plus (P=0.4). Vicryl® Plus sutures showed the highest accumulation of E. coli followed by Vicryl®, silk and nylon (P<0.01). Vicryl® sutures showed the highest accumulation of S. mutans, followed by Vicryl® Plus, silk, and nylon. Vicryl® Plus sutures showed the highest accumulation of S. aureus, followed by Vicryl®, nylon, and silk.

Nylon sutures showed the least microbial accumulation. Vicryl® and triclosan-coated Vicryl® Plus sutures had no advantage over the commonly used silk sutures in decreasing the number of bacteria.

A well-designed vaccine against Streptococcus pneumonia, a respiratory pathogen, by immunoinformaticsapproaches can lead to an effective mucosal and local immunity in the upper respiratory tract. In this study, we chose virulence proteins from different strains of S. pneumonia(Pneumolysin, Neuraminidase, Zink-Metalloproteinase, and Hydrolase) and designed a new multi-epitope construct by properly linking the individual predicted T and B cell specific epitopes. Then, the polytope, named PNEU, was expressed in Escherichia colias a prokaryotic system. Through computational calculations, PNEU polypeptide with 216 aa has the theoretical pI 8.04 and instability index 33.63, which show that it is a stable and soluble protein. Also, the 3D structure of PNEU was predicted by Phyre2 server with 96.0% confidence.In conclusion, PNEU protein can be considered as a stable and soluble immunogenic protein, which may be efficiently used for immunity stimulation in laboratory animals, investigated in future studies.

 Group B Streptococcus (GBS) causes a wide range of adverse effects in both mothers and infants during pregnancy and after delivery.

 This study aimed to evaluate the effects of erythromycin either alone or in combination with gold nanoparticles (AuNPs) on the clinical GBS isolated from pregnant women.

 This descriptive cross-sectional study was performed on 106 women aged 16 - 48 years. After identification of GBS strains by phenotypic and genotypic methods (PCR), erythromycin-resistant isolates were identified using the Kirby-Bauer test and broth microdilution method according to CLSI-2015 guidelines. The antibacterial properties and minimum inhibitory concentration (MIC) of erythromycin (either alone or combined with AuNPs) were assessed by the agar well-diffusion and broth microdilution methods, respectively.

 The frequency of GBS isolates was significantly high in the pregnant women aged less than 40 years (73.9%) (P = 0.0251), those with a history of abortion (60.9%) (P = 0.038), and residents of rural areas (60%) (P = 0.038). Moreover, 65.2% of the isolates were resistant to erythromycin. The MIC of AuNPs-erythromycin combination required to inhibit the growth of 50% of GBS isolates (MIC50 = 0.25 μg/mL) was significantly lower than the concentration of AuNP-erythromycin required to inhibit the growth of 90% of the isolates (MIC90 = 1 μg/mL) (P = 0.02), indicating a 16-fold lower dose than the values for erythromycin and AuNPs alone. In the agar well-diffusion method, the average diameter of the growth inhibition zone of AuNPs-erythromycin was 2.5-fold greater than that of free erythromycin (P = 0.037).

 The results showed that the combination of erythromycin with AuNPs increased the antibacterial effects of erythromycin against GBS isolates.

Necrotizing fasciitis is a potentially fatal infection of β hemolytic Group-A Streptococcus, often occurring in patients with other comorbidities, but can occur in healthy individuals as well. It commonly affects the extremities, perineum, and abdominal wall. The aim of this study was to highlight various presentations of necrotizing fasciitis in unusual anatomical sites with delayed diagnosis and treatment. 

In a retrospective analysis, seven cases of unusual presentations of necrotizing fasciitis were enrolled during a period of five years treated in a tertiary center.

The patients were between 23 and 80 years. Four were males and three were females. Four out of seven were diabetic. All patients had septicemia (hypovolemic shock, with leucocytosis, thrombocytopenia and deranged coagulation parameters) on admission in the intensive care unit. All seven patients had minimal cutaneous manifestation and the remote primary pathology was diagnosed in two patients. Six patients out of seven survived and the morbid state continued in one patient in view of malignancy of rectum in one patient. The overall outcome was satisfactory in five out of seven cases.

Pain disproportionate to the local inflammation with florid constitutional symptoms should raise suspicion of necrotizing fasciitis. Early diagnosis, of stabilization of hemodynamics, emergency fasciotomy, staged debridement and the initiation of broad spectrum antibiotics reduced the morbidity and mortality. The disease may manifest with uncommon presentations and sometimes lead to the diagnosis of primary aetiology.

Antibodies are important agents in the laboratory diagnosis of various microorganisms such as Streptococcus pneumoniae. In this study, we prepared and purified IgG antibody against Streptococcus pneumoniae using novel methods to be used in ELISA and agglutination diagnostic kits. First, Streptococcus pneumoniae was cultured, harvested, and inactivated. Then, bacteria were injected into four mature New Zealand white rabbits, and antisera were developed. Afterward, immunoglobulins were purified using ammonium sulfate precipitation, diafilteration using Tangential Flow Filtration, and ion-exchange chromatography. The purified antibody was then biotinylated and used in ELISA. Gel electrophoresis results showed that the antibody was highly pure. Agglutination test on the primary antigen and clinical samples was four-plus. ELISA results showed that the sensitivity and specificity of the test were 95% and 100%, respectively. Results indicated that our fast method was suitable for anti-Streptococcus pneumoniae IgG purification. Repetitive qualitative and quantitative experiments confirmed high purity of the immunoglobulin. Thus, it could be a suitable candidate to be used in laboratory diagnostic kits.

Acute bacterial conjunctivitis is a common, highly contagious infection in children and is usually treated empirically with broad spectrum topical antibiotics. In the current study we investigated bacteriology and antibiotic susceptibility patterns in childhood acute bacterial conjunctivitis in Western Greece. We conducted a retrospective analysis of presumed acute bacterial conjunctivitis cases in ''Karamandaneio'' Pediatric General Hospital of Patras, Western Greece, between February 1, 2013 and January 31, 2018. Specimens from the lower conjunctiva fornix were isolated from 191 cases and outcomes were analyzed to identify the pathogenic bacteria of acute bacterial conjunctivitis and their corresponding antibiotic susceptibility patterns. Patients were divided into 3 groups; Group A included neonates under 28 days of life, Group B children from 1 month to 2 years and Group C from 2 years to 14 years. Results revealed that Staphylococcus spp., Haemophilus spp. and Streptococcus spp. were the most prevalent pathogens. No significant differences in isolated pathogens were found between the age groups. Antibiotic resistance rates were higher against ampicillin, ceftriaxone, ceftazidime and sulfamethoxazole. Resistance rates to Ciprofloxacin were low while none of the evaluated isolates were resistant to vancomycin. We concluded that predominant pathogens of childhood acute bacterial conjunctivitis in Western Greece were Staphylococcus spp., Haemophilus spp. and Streptococcus spp. Continuous surveillance, focused in distinct geographic areas, is encouraged to prepare more precise protocols of empirical treatment.

Probiotics and prebiotics are known to regulate immune responses. A synbiotic is a product that combines probiotics and prebiotics in a single dosage form. In this study, we attempt to present the effects of a multispecies synbiotic on intestinal mucosa immune responses after exposure to Escherichia coli O55:B5 lipopolysaccharide (LPS).

Totally 21 male Balb/c mice were randomly classified into two groups. The K-I group received LPS and a synbiotic, and the K-II group received LPS alone. The synbiotic was administered for 21 consecutive days, whereas LPS was administered once on the 15th day. Specifically, a synbiotic containing 1 × 109 colony forming units (CFUs) of the probiotic combination of Lactobacillus acidophilus PXN 35, L. casei subsp. casei PXN 37, L. rhamnosus PXN 54, L. bulgaricus PXN 39, Bifidobacterium breve PXN 25, B. infantis PXN 27 and Streptococcus thermophilus PXN 66 and the prebiotic fructo-oligosaccharide was administered through an orogastric tube. Immunohistochemistry was performed to measure immunoglobulin A (IgA) levels for humoral immune responses and CD4+ and CD8+ levels for cellular immune responses.

An independent-samples t-test revealed significant increases of the numbers of IgA- (p = 0.027) and CD4-expressing cells (p = 0.009) but not the number of CD8-expressing cells in the K-I group compared with those in the K-II group.

The multispecies synbiotic had immunoregulatory effects on IgA and CD4 expression in LPS-exposed mice.

Group A streptococci (GAS) are notorious bacteria causing a wide variety of clinical manifestations ranging from mild, acute streptococcal pharyngitis to chronic non-suppurative diseases and immunological sequelae. They are further complicated by the global rise on the emergence of macrolide resistance among these bacteria in which several M protein gene (emm) and sequence types are associated with invasive diseases.
The current study aimed at determining the erythromycin resistance patterns and molecular characteristics of GAS clinical strains by emm and multilocus sequence typing (MLST) methods.
Thirty-five GAS clinical isolates were subjected to antibiotic susceptibility testing by disk diffusion method. The minimum inhibitory concentration (MIC) of erythromycin against GAS by E-test was determined. Clinical and laboratory standards institute (CLSI) guideline was used for the interpretation of results. Detection of ermA, ermB, and mefA genes by polymerase chain reaction (PCR) was performed and emm typing was done by amplification and sequencing of emm genes per standard protocol. Allele and sequence type (ST) of GAS were obtained using the S. pyogenes MLST database.
All the isolates were sensitive to erythromycin, penicillin, clindamycin, chloramphenicol, and vancomycin (100%). Resistance to tetracycline was 54.3%. The mefA gene was found in one erythromycin susceptible isolate. No other erythromycin resistance genes were detected in the isolates. Twenty different emm types were found and the most frequent emm types/subtypes detected were emm1, emm18.21, emm28.5, emm97.4, and emm102.2 (each 8.6%). However, no new emm type was detected. A total of 15 sequence types (STs), eight clonal clusters (CCs), and eight singletons were identified among 21 representative isolates. Three isolates exhibited CC1 (ST28/emm1).
High susceptibility of GAS isolates against erythromycin could be due to low antibiotic selective pressure in Malaysian clinical settings. High diversity of emm and ST types revealed the heterogenic nature of the strains circulating in Malaysian hospitals. Continuous epidemiological monitoring by molecular typing methods is warranted to improve the management strategies of GAS infections in future.

The aim of this study was to evaluate the antimicrobial effects of essential oils (EOs) isolated from Myrtus communis L. (myrtle) against Streptococcus mutants, Streptococcus sanguis, and Streptococcus salivarius through in vitro experiments. The EOs was isolated from myrtle leaves by the hydrodistillation method. The disc diffusion method was used to evaluate the zone of microbial growth inhibition by different concentrations of the EOs. The inhibition zone for all concentrations was measured in diameter (MM) after incubation at 37° for 18 hours. According to these measurements, the Minimal inhibitory concentration for each bacterium was reported. Tetracycline and erythromycin were used as positive control. The result showed that EOs of myrtle leaves had antimicrobial activity on disk-diffusions plates against all strains of Streptococcus, which were tested; however, S. mutants showed greater susceptibility than others. EOs of myrtle leaves could be recommended as a potential remedy for prevention the colonization of teeth by Streptococcus mutants and hinder the development of dental caries.

Currently, developing new antibacterial drugs as alternative antibiotics is a very active area of research, due to widspreading widespread prevalence of resistant strains of microorganisms. This work intends to investigate of antibacterial properties and influence on immune blood cells of the silver-based compound hexamethylenetetramine (methenamine) silver nitrate with general formula [Ag(CH2)6 N4]NO3.
The antibacterial effect of the silver complex was investigated by agar diffusion and serial dilution methods. Silver complex have been investigated for its impact on the phagocytic activity of neutrophils and on immune cells during the reaction of blast transformation of lymphocytes (RBTL).
Studies have shown that hexamethylenetetramine silver nitrate possesses both bactericidal and bacteriostatic dose-dependent effect on tested bacterial strains, including Staphylococcus aureus, Proteus vulgaris, Pseudomonas aeruginosa, Streptococcus pneumoniae. Escherichia coli were shown to be the most susceptible bacteria. Cytotoxic effect of silver salt on lymphocytes was detected in high dosage in RBTL. No significant immunosuppressive impact on neutrophils phagocytic activity of tested complex was shown.
Agents of nosocomial infections were highly susceptible to the drug. Complex has proved to be promising as a prospective antibacterial drug with wide range of activity.

Resistance toward quaternary ammonium compounds (QACs) is widespread among a diverse range of microorganisms and is facilitated by several mechanisms such as biofilm formation.. In this study, the effects of benzalkonium chloride on planktonic growth and biofilm formation by some field isolates of animal bacterial pathogens were investigated.. Forty clinical isolates of Escherichia coli, Salmonella serotypes, Staphylococcus aureus and Streptococcus agalactiae (10 isolates of each) were examined for effects of benzalkonium chloride on biofilm formation and planktonic growth using microtiter plates. For all the examined strains in the presence of benzalkonium chloride, biofilm development and planktonic growth were affected at the same concentrations of disinfectant.. The means of strains growth increase after the minimal inhibitory concentration (MIC) were significant in all the bacteria (except for E. coli in 1/32 and S. agalactiae in of 1/8 MIC). Biofilm formation increased with decrease of antiseptics concentration; a significant increase was found in all the samples. The most turbidity related to S. aureus and the least to Salmonella.. Bacterial resistance against quaternary ammonium compounds is increasing which can increase the bacterial biofilm formation..

Use of alternative medicine to control oral streptococci is a new topic worthy of further investigation.This study aimed to elucidate the dose-dependent anti-bacterial activity of crude aqueous extract of ripe Morinda citrifolia L. (Family: Rubiaceae) fruits against oral streptococci i.e. Streptococcus mutans and Streptococcus mitis, that cause dental caries in humans. Fresh ripe M. citrifolia fruits (750g) were ground in an electronic blender with sterile water (500ml). The crude aqueous extract was lyophilized to yield a brown colored powder. Various concentrations (1000-100µg/ ml) of the extract were tested for its anti-bacterial activity (Kirby and Bauer method) against whole cells of S. mutans and S. mitis. Minimum Inhibitory Concentration (MIC) was determined by micro-dilution method, using serially diluted (2 folds) fruit extract, according to the National Committee for Clinical Laboratory Standards (NCCLS). Crude aqueous extract (1000µg/ ml) of ripe M. citrifolia fruits effectively inhibited the growth of S. mutans (19±0.5 mm) and S. mitis (18.6±0.3 mm) compared to the streptomycin control (21.6±0.3 mm). The growth inhibition was clearly evident with “nil” bacteriostasis, even after 48 hours of incubation at 37°C. The MIC of the extract for S. mutans and S. mitis was 125 µg and 62.5 µg, respectively. Our results suggest that phytochemicals naturally synthesized by M. citrifolia have an inhibitory effect on oral streptococci. Furthermore, purification and molecular characterization of the “bioactive principle” would enable us to formulate a sustainable oral hygiene product.