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Streptococcus pneumoniae transformation occurs within a short competence window, during which the alternative sigma factor X (SigX) is activated to orchestrate the expression of genes allowing extracellular DNA uptake and recombination. Importantly, antibiotic stress promotes transcriptional changes that may affect more than 20% of the S. pneumoniae genome, including competence genes. These can be activated or repressed, depending on the antibiotic agent. For most antibiotics, however, it remains unknown whether transcriptional effects on competence translate into altered transformability. Here we investigate the effect of antibiotic subinhibitory concentrations on sigX expression using a luciferase reporter, and correlate for the first time with transformation kinetics. Induction of sigX expression by ciprofloxacin and novobiocin correlated with increased and prolonged transformability in S. pneumoniae. The prolonged effect of ciprofloxacin on competence and transformation was also observed in the streptococcal relatives Streptococcus mitis and Streptococcus mutans. In contrast, tetracycline and erythromycin, which induced S. pneumoniae sigX expression, had either an inhibitory or a nonsignificant effect on transformation, whereas streptomycin and the β-lactam ampicillin, inhibited both sigX expression and transformation. Thus, the results show that antibiotics may vary in their effects on competence, ranging from inhibitory to stimulatory effects, and that responses affecting transcription of sigX do not always correlate with the transformation outcomes. Antibiotics that increase or decrease transformation are of particular clinical relevance, as they may alter the ability of S. pneumoniae to escape vaccines and antibiotics.

We report a rare case of meningitis due to a combination of Streptococcus mitis and Neisseria subflava. An 80-year-old female had a 4-year history of type II diabetes mellitus (DM) and an 11-year history of rheumatoid arthritis, which was treated with prednisolone, tacrolimus, and methotrexate. One month after the removal of a dental implant, she complained of a disturbance of consciousness and suffered a convulsion. A cerebrospinal fluid culture was found to be positive for both S. mitis and N. subflava. After 14 days of antibiotic treatment with 4 g/day ceftriaxone, her stiff neck, somnolence, and laboratory data greatly improved, and she was successfully discharged at 27 days after admission. Although both S. mitis and N. subflava are generally considered to be benign bacteria, they can cause meningitis in patients with the following risk factors: older age, on immunosuppressive treatment, DM, or dental treatment.

The purpose of this study was to describe the distribution of streptococci causing infective endocarditis (IE). A total of 296 patients with definite IE admitted from July 2007 to December 2014 were identified, with microbial identification done by a combination of blood culture, valve culture, and valve polymerase chain reaction (PCR). The overall distribution of streptococci was 76% viridans (n = 224), 17% pyogenic (50), 6% nutritionally variant (17), and 2% anaerobic (5). Sixty-three (21%) viridans group streptococci were not identified further. The distribution of the remaining 161 viridans group streptococci was Streptococcus mitis group 61%, S. bovis group 15%, S. mutans group 13%, S. anginosus group 9%, and S. salivarius group 1%. Of the 50 pyogenic streptococci, 78% were S. agalactiae and 16% were S. dysgalactiae. PCR was significantly more sensitive than culture in identifying streptococci in excised heart valves.

We report a rare case of meningitis due to a combination of Streptococcus mitis and Neisseria subflava. An 80-year-old female had a 4-year history of type II diabetes mellitus (DM) and an 11-year history of rheumatoid arthritis, which was treated with prednisolone, tacrolimus, and methotrexate. One month after the removal of a dental implant, she complained of a disturbance of consciousness and suffered a convulsion. A cerebrospinal fluid culture was found to be positive for both S. mitis and N. subflava. After 14 days of antibiotic treatment with 4 g/day ceftriaxone, her stiff neck, somnolence, and laboratory data greatly improved, and she was successfully discharged at 27 days after admission. Although both S. mitis and N. subflava are generally considered to be benign bacteria, they can cause meningitis in patients with the following risk factors: older age, on immunosuppressive treatment, DM, or dental treatment.

Purpose: To raise awareness of a possible association between continuous positive airway pressure (CPAP) devices and postoperative bleb-related infection. Observations: A 57-year old patient on CPAP presented with unilateral bleb-associated endophthalmitis 32 months after routine ExPress Trabeculectomy with mitomycin C. The offending organism, Streptococcus mitis, is a nonmotile and generally non-virulent pathogen which predominates in the normal human respiratory flora. Conclusions and importance: This conceptual report underscores a potential relationship between CPAP use and bleb-associated endophthalmitis. Streptococcal species are the most commonly reported causative organisms in bleb-associated endophthalmitis, and S. mitis is of particular concern as the most abundant microbe among all human oral flora. A logical risk factor for infection, the CPAP device may inadvertently deliver such organisms to the vulnerable conjunctival filtering bleb. Keywords: Endophthalmitis, Bleb, Mitomycin C, Express trabeculectomy, Continuous positive airway pressure, Streptococcus mitis

The aetiology of erysipelas remains poorly defined though beta-haemolytic streptococci are considered as the main causative pathogens. We describe a case of a 70-year-old woman with recurrent erysipelas in her left arm due to infection with streptococci of the mitis group. Her past medical history includes lymphoedema of the left arm secondary to lymph node dissection due to breast cancer surgery. On seven different occasions during a decade, she has presented a clinical picture of erysipelas and in three of them with Streptococcus mitis group bacteraemia. The results indicate that two cases were caused by Streptococcus mitis and one case was caused by Streptococcus oralis. This is, to our knowledge, the first reported cases of S. mitis and of S. oralis as the causative agents of erysipelas.

Acute respiratory infection is a serious health problem in the world and in Indonesia. Acute respiratory infection is caused by a variant of the bacteria and resistance to antibiotics. The Latest researches on antibacterial compounds based on natural ingredients have been conducted. One of them is derived from green algae. This study aims to determine the antibacterial activity of green algae Caulerpa racemosa extract in inhibiting the growth of pathogenic bacteria causing acute respiratory infection. This study includes an extraction process using chloroform. Antibacterial testing was done by using a concentration of 0.5%, 1%, 5%, 10%, 20%, 40%, 60% and 80%, in order to obtain the minimal Inhibitory Concentration. The results showed that C . racemosa extract was able to inhibit the growth of test bacteria Streptococcus mitis, Bacillus anthrachis, and B . cereus , with the best activity at concentration of 0.5% and 80%. Meanwhile the extract did not have the activity to inhibit the Gram-negative bacteria. Phytochemical test showed that chloroform of C . racemosa extract contain steroids and terpenoids compounds capable of inhibiting the growth of testing bacteria. Key words : antibacterial activity, C. racemosa , pathogenic bacteria, Acute respiratory infection

Objectives Chlorhexidine is seen as the golden standard of disinfectants. It is widely used to clean surgical sites; however, many studies indicate resistance of pathogens to chlorhexidine. One study indicated that pathogenic microorganisms were isolated from the soft palate cleft region in 57% of patients with facial clefts. The objectives of our study were to determine (1) if chlorhexidine application is effective in removing pathogens from the surgical site in these patients, and (2) if any pathogens are isolated, determine if they are resistant to other antimicrobials. Design A descriptive observational study. Settings A private practice that specializes in facial cleft surgery, with a country-wide patient base. All procedures were executed by one oral and maxillofacial surgeon. Participants All patients (N=50) who presented for primary repair of the soft palate cleft were included in the study. Inclusion criteria written consent from parent(s), and patient cleared as systemically healthy by a pediatric physician. Exclusion criteria patient(s) with systemic infections (eg, flu) and/or any local infections (eg, tonsillitis). There were 25 males and 25 females with an average age of 7 months and 16 days included in the study. Methods Swabs were taken from the surgical site of all 50 patients with cleft soft palate and were sent for culture, identification and antimicrobial sensitivity. The swabs were taken before disinfecting the site as well as after 2 minutes of disinfecting the surgical site with chlorhexidine. Results were compared against each other. Results Positive cultures with 28 different pathogenic microorganisms that were identified in 47 patients before cleaning the surgical site with the chlorhexidine. The most dominant pathogens were K. pneumonia (n=22), H. influenza (n=18) and S. aureus (n=10). Of the pathogens found, 13 (46%) were still present on the swabs taken after disinfecting with chlorhexidine. K. pneumonia (n= 13), H. influenza (n=11) and S. aureus (n=9) were still the most prevalent pathogens. Conclusions This study demonstrated that 61 of the total of 113 pathogens isolated (54%), survived after 2 minutes of disinfecting the surgical and surrounding area with chlorhexidine, thus intensifying the chances of post-operative infection.

The use of plants in the prevention and treatment of oral infectious and as an antibiofilm agent continues to be valued in many parts of the world. The aim of study is to evaluate in vitro antimicrobial action of the plant extracts of barks Mimosa tenuiflora (Willd.), Poir. (jurema preta) and leaf and stem of Myrciaria cauliflora Berg. (jabuticabeira) against dental biofilm bacteria. The oral bacteria were used to determine the minimum inhibitory concentration (MIC) and minimum inhibitory concentration of adherence (MICA): Streptococcus mitis, Streptococcus mutans, Streptococcus sanguinis, Streptococcus oralis, Streptococcus salivarius and Lactobacillus casei. Each assay was carried out in duplicate and the positive control (0.12% chlorhexidine digluconate) was subjected to the same procedure. Results were analyzed by Student t test or Mann-Whitney test, with the level of significance set at 5%. The extract of M. tenuiflora showed inhibition halos ranging from 10 to 25 mm in diameter, presenting an average performance superior to chlorhexidine digluconate, being statistically significant only at the concentration of 1:128 (3.9 mg/mL). The leaf and stem extracts of M. cauliflora were found to have inhibition halos varying from 10 to 18 mm in diameter and presented a significantly lower average performance in relation to chlorhexidine digluconate in crude extract (500 mg/mL) concentration; 1:2 (250 mg/mL) and 1:4 (125 mg/mL) and crude extract (500 mg/mL), 1:2 (250 mg/mL), 1:4 (125 mg/mL) and 1:8 (62 mg/mL), respectively. All extracts studied were effective in the inhibition of adherence, especially the stem extract of M. cauliflora (1:64/ 7.81 mg/mL). Conclusively, the extracts of M. tenuiflora and M. cauliflora produced a significant bactericidal activity and in vitro anti-adherent effect on the bacteria forming the dental biofilm, which suggests the use of these substances as an alternative and economically viable means for the control of infections in dentistry. Key words: Microbiology, phytotherapy, Mimosa tenuiflora (Willd.) Poir., Myrciaria cauliflora Berg.

Background Subdural empyema can present as a spinal subdural empyema (SSE) or a cranial subdural empyema (CSE). Although they differ somewhat in epidemiology, etiology, pathophysiology, and symptomatology and occur separately, they rarely manifest together. The aim of this article is to review the literature concerning the clinical presentation, clinical course, and treatment options for managing concurrently occurring SSE and CSE. Methods The literature in the Medline database was reviewed with key words including but not limited to subdural empyema, retroclival empyema, and Streptococcus mitis . No similar reports were found in the database involving infection with this type of microorganism in this anatomical region. Results Only 3 cases with concurrent CSE and SSE were found in the literature caused by various etiologic agents. Two of the patients recovered with no neurologic deficit, whereas one fatality was reported. One new illustrative case caused by Streptococcus mitis is also presented. Conclusions CSE and SSE are neurosurgical emergencies, often requiring prompt surgical evacuation. Although very rare, Streptococcus mitis can cause spinal subdural empyema or retroclival abscesses. Natural history of this disease is grave without treatment. Delays in diagnosis and treatment are directly related to mortality and severe morbidity in patients with intracranial and spinal subdural empyema. Prompt recognition and treatment are essential to preclude severe neurologic disabilities or in rare cases a fatal outcome. A treatment paradigm for cranio-spinal empyema is proposed.

A novel silver nanoparticle (AgNP) formulation was developed as a targeted application for the disinfection of carious dentine. Silver nitrate (AgNO3) was chemically reduced using sodium borohydrate (NaBH4) in the presence of sodium dodecyl sulfate (SDS) to form micelle aggregate structures containing monodisperse 6.7- to 9.2-nm stabilized AgNPs. AgNPs were characterized by measurement of electrical conductivity and dynamic light scattering, scanning electron microscopy, transmission electron microscopy, and inductively coupled plasma mass spectrometry. Antimicrobial activity of AgNPs was tested against planktonic cultures of representative gram-positive and gram-negative oral bacteria using well diffusion assays on tryptic soy broth media and monoculture biofilms grown with brain heart infusion ± sucrose anaerobically at 37°C on microtiter plates. Biofilm mass was measured by crystal violet assay. Effects were compared to silver diamine fluoride and chlorhexidine (negative controls) and 70% isopropanol (positive control) exposed cultures. In the presence of AgNPs, triplicate testing against Streptococcus gordonii DL1, C219, G102, and ATCC10558 strains; Streptococcus mutans UA159; Streptococcus mitis I18; and Enterococcus faecalis JH22 for planktonic bacteria, the minimum inhibitory concentrations were as low as 7.6 µg mL-1 and the minimum bacteriocidal concentrations as low as 19.2 µg mL-1 silver concentration. Microplate readings detecting crystal violet light absorption at 590 nm showed statistically significant differences between AgNP-exposed biofilms and where no antimicrobial agents were used. The presence of sucrose did not influence the sensitivity of any of the bacteria. By preventing in vitro biofilm formation for several Streptococcus spp. and E. faecalis, this AgNP formulation demonstrates potential for clinical application inhibiting biofilms.

Objectives The present study aimed to assess the antibacterial activity against bacteria with cariogenic relevance, toxic and genotoxic potential of the plants Anacardium occidentale L. and Anadenanthera macrocarpa (Benth.) Bernam. Design Using a microdilution technique, the extracts were submitted to minimum inhibitory concentration (MIC) testing against Streptococcus mitis (ATCC 903), Streptococcus mutans (ATCC 25175), Streptococcus oralis (ATCC 10557), Streptococcus salivarius (ATCC 7073), Streptococcus sanguinis (ATCC 15300) and Streptococcus sobrinus (ATCC 27609). The toxicity of the extracts was then verified against eukaryotic cells. Additionally, a micronucleus assay was performed to investigate the potential mutagenic effects of the extracts on rat erythrocytes. The Student’s t -test, Bonferroni test, and one-way ANOVA followed by Tukey’s tests were used for statistical analysis, at a significance level of 5%. Results While the A. occidentale extract was able to inhibit all of the tested strains, with S. mutans and S. mitis being the most susceptible to that extracts action, the A. macrocarpa did not show antimicrobial activity. Interestingly, the hemolytic, oxidant and antioxidant activities were slightly observed for either extract, even at high concentrations (1000 mg/mL). The micronucleus assay showed no significant changes in the cells exposed to the extracts. Conclusion The A. occidentale extract has potential as an antimicrobial agent with low eukaryotic cell toxicity or mutagenic activity. The A. macrocarpa extract, although absent of antibacterial activity might as well be a safe and effective phytotherapeutic alternative.

A 52-year-old man presented with a fever and malaise. Transthoracic echocardiogram was performed because of a holosystolic murmur, which showed mitral valve prolapse and a regurgitation jet toward the posterior wall of the left atrium. There was no apparent vegetation at any valves. Blood cultures were positive for Streptococcus mitis/oralis. Transesophageal echocardiogram revealed vegetation only at the posterior wall of the left atrium exposed to the mitral regurgitant jet. We diagnosed this condition as infective mural endocarditis. This case highlighted the need for a detailed observation of the valves and the atrial wall when infective endocarditis is suspected.

Although Streptococcus anginosus constitutes a proportion of the normal flora of the gastrointestinal and genital tracts, and the oral cavity, it has been reported that S. anginosus infection could be closely associated with abscesses at various body sites, infective endocarditis, and upper gastrointestinal cancers. The colonization in an acidic environment due to the aciduricity of S. anginosus could be the etiology of the systemic infection of the bacteria. To elucidate the aciduricity and acid tolerance mechanisms of the microbe, we examined the viability and growth of S. anginosus under acidic conditions. The viabilities of S. anginosus NCTC 10713 and Streptococcus mutans ATCC 25175 at pH 4.0 showed as being markedly higher than those of Streptococcus sanguinis ATCC 10556, Streptococcus gordonii ATCC 10558, and Streptococcus mitis ATCC 49456; however, the viability was partially inhibited by dicyclohexylcarbodiimide, an H+-ATPase inhibitor, suggesting that H+-ATPase could play a role in the viability of S. anginosus under acidic conditions. In addition, S. anginosus NCTC 10713 could grow at pH 5.0 and showed a marked arginine deiminase (ADI) activity, unlike its ΔarcA mutant, deficient in the gene encoding ADI, and other streptococcal species, which indicated that ADI could also be associated with aciduricity. These results suggest that S. anginosus has significant aciduric properties, which can be attributed to these enzyme activities.

Patient: Male, 47 Final Diagnosis: Pulmonic valve endocarditis Symptoms: Fever • myalgia Medication: — Clinical Procedure: — Specialty: Cardiology Objective: Rare disease Background: Infective endocarditis (IE) has a high mortality rate, even when treated with appropriate antibiotic therapy and surgical intervention. Right-sided endocarditis is in itself rare, with some studies reporting an incidence of 5–10%. The majority of these cases involve the tricuspid valve, and isolated pulmonary valve endocarditis (PVE) is an extremely rare entity affecting less than 2% of patients with infective endocarditis. Identification and early management are crucial to prevent long-term complications and reduce mortality. Case Report: We present a patient with a history of essential hypertension and no underlying valvular disease, who underwent dental cleaning and subsequently developed low-grade fever, myalgia, and malaise. This occurred during the flu season, and was initially diagnosed and treated as flu, without any improvement. The patient was later found to be bacteremic with S. mitis, with no identifiable source, and a normal transthoracic echocardiogram (TTE). He was later hospitalized, had a transesophageal echocardiogram, and was found to have a large pulmonic valve vegetation. Conclusions: This case presents an interesting and rare finding of endocarditis, isolated to the pulmonic valve, in an otherwise healthy individual with no predisposing risk factors. The lack of peripheral stigmata, as well as an unremarkable initial outpatient TTE, made the diagnosis more difficult. It should also be noted that current guidelines do not specifically address right-sided endocarditis, and do not specify the role of surgical intervention.

Background The amniotic membrane (AM) is used in ocular surface reconstruction and is effective at promoting epithelialization and preventing corneal perforation in cases of acute microbial keratitis. Here, we report a case of isolated AM infection after AM transplantation for a persistent epithelial defect following tectonic penetrating keratoplasty. Case presentation A 47-year-old man with poorly controlled type 2 diabetes mellitus presented to the emergency department with a referral for perforated microbial keratitis. After ophthalmic examination, corneal scraping was performed, and corneal gluing was attempted and failed. Hence, the patient underwent tectonic penetrating keratoplasty. After keratoplasty, the patient developed a persistent epithelial defect that required AM transplantation as an overlay. Thirty days post-AM transplant, the patient presented with signs and symptoms resembling granular microbial infection of the cornea. After two days, the granular findings began dislodging from the corneal surface and were sent for culture, sensitivity, and histopathological identification. Histological analysis of the granular material indicated it to be a small piece of AM stroma infiltrated with mixed-type inflammatory cells. Corneal scraping cultures indicated Streptococcus mitis and Streptococcus oralis. Conclusion The infiltrate was localized to the basement membrane of the AM as, despite the anti-inflammatory effects of AM, it can also act as a barrier against polymorphonuclear leukocyte infiltration from the tear film and microbial invasion into the cornea.

Objectives: Streptococcus tigurinus is a new member of the Streptococcus mitis group. It causes various invasive infections. Its isolation from the oral cavity has been reported recently for the first time in our previous study. An attempt has been made to develop a novel in vitro model for the study of development of resistance to penicillin and to find out its effect on susceptibility pattern of other antimicrobial agents in an isolate of S. tigurinus . Materials and Methods: An in vitro model mimicking in vivo conditions was developed to induce resistance in S. tigurinus with MIC value of 0.12 µg/ml to penicillin by 10 serial passages by sequential exposure to increasing concentration of penicillin. Results: The in vitro manipulation of original strain of S. tigurinus resulted in an increase in MIC value to 8 µg/ml indicating development of resistance to penicillin and a major increase in MIC value of ampicillin from 0.25 to 16 µg/ml, and increase in MIC values of cefepime (0.12 to 0.25 µg/ml), erythromycin (0.12 to 0.25 µg/ml), azithromycin (0.5 to 1 µg/ml) and clarithromycin (0.25 to 0.5 µg/ml) indicating development of cross-resistance to these antimicrobial agents. Conclusion: Results indicate that exposure to increasing concentrations of penicillin can induce the development of resistance to penicillin and cross-resistance to other antimicrobial agents. As in vitro conditions are quite similar to in vivo situation, the results obtained are more appreciable than routine methods using artificial media.

A 67-year-old woman presented with painful, acute vision loss after 5 days of fever and muscle aches while visiting the Dominican Republic. She had no recent history of ocular surgery, dental work or recent trauma. Anterior chamber aspiration confirmed an initial diagnosis of endogenous endophthalmitis, positive for Streptococcus mitis that progressed to panophthalmitis on return to Canada. Treatment included systemic antibiotics, intravitreal antibiotics and intravitreal dexamethasone. Despite the best medical treatment, the left eye progressed to corneal perforation 5 weeks after presentation. An evisceration with fitted orbital implant was successful in alleviating pain following the surgery. S. mitis is a rare, but possible cause of endogenous endophthalmitis and panophthalmitis. It was important to work with a multidisciplinary and global team to coordinate and offer appropriate treatment measures. Although vision was lost, evisceration of the left eye provided ocular comfort and good cosmetic outcomes for the patient.

Background: Periapical lesions are primarily caused by infections in the root canals. The objective of this study was to assess the antibacterial effectiveness of diode laser during root canal treatment in artificial models of infected periapical lesions. Material and methods: One hundred twenty-two extracted premolar single- rooted teeth were inserted into methyl methacrylate artificial models of periapical lesions, and bacterial solutions of Enterococcus faecalis (ATCC 29212) and Streptococcus mitis (ATCC 49456) were then applied to the models. The respective diameters of lesions in the artificial models represented 3 different subgroups based on lesion size. The laser protocol used for endodontic disinfection had a power output of 1.5 W and a wavelength of 810 nm. The impact on cell viability was evaluated by flow cytometry. Results: Disinfection with laser did not differ between microorganisms (P=0.137), and laser irradiation with a longer duration had better disinfecting action for both microorganisms (P

Purpose: This in vitro study tested the effects of argon atmospheric pressure dielectric barrier discharge (APDBD) on different implant surfaces with regard to physical changes, bacterial decontamination, and osteoblast adhesion. Materials and Methods: Seven hundred twenty disks with three different surface topographies- machined (MAC), titanium plasma-sprayed (TPS), and zirconia-blasted and acid-etched (ZRT)-were tested in this experiment. Bacterial adhesion tests were performed repeatedly on a simplified biofilm of Streptococcus mitis. Bacteria were incubated in the presence of the samples, which were subsequently either left untreated as controls or treated with APDBD for 30, 60, and 120 seconds. Samples were then metalized, prior to the recurring acquisition of images using a scanning electronic microscope (SEM). Protein adsorption, surface wettability, and early biologic response were determined for both treated (120 seconds) and untreated implant surfaces. For depicting the eukaryotic cell behavior, preosteoblastic murine cells were used. Cells were conveniently stained, and nuclei were counted. Cell viability was assessed by a chemiluminescent assay at 1, 2, and 3 days. Results: On all treated samples, values of the contact angle measurements were lower than 10 degrees. The untreated samples showed values of contact angle of 80, 100, and 110 degrees, respectively, for MAC, TPS, and ZRT. The protein adsorption on TPS and ZRT was significantly increased after the plasma of argon treatment. However, no significant effect was noted on the MAC disks. The number and the cell spreading area of adherent osteoblasts significantly increased in all treated surfaces. Nonetheless, argon treatment did not influence the osteoblast proliferation and viability at different time points. Bacteria adhesion was significantly reduced, even after 60 seconds of argon treatment. Conclusion: Preliminary data showed that argon atmospheric pressure dielectric barrier discharge disinfected the implant surface, with potential to promote osteoblast attachment and spreading, suggesting this may be a possible approach to clean a peri-implantitis-contaminated implant surface.

Endophthalmitis following intraocular surgery can be devastating. This case report demonstrates successful management of late-onset Streptococcus mitis endophthalmitis treated by vitrectomy, panretinal photocoagulation (PRP) and silicone oil tamponade. A 75-year-old man presented with painful vision loss in his right eye. The patient had uneventful phacoemulsification and intraocular lens implantation in the right eye at an outside clinic 6 weeks prior. Examination disclosed hypopyon and vitritis, as well as discrete inflammatory collections in the vitreous. The patient underwent vitrectomy with PRP and silicone oil tamponade. Vitreous cultures were positive for S. mitis, a pathogen associated with severe tissue damage and poor clinical outcomes. One month after the surgery, intraocular inflammation was stabilized, and visual acuity was improved from light perception to 20/200. Aggressive surgical management may play a role in improving outcomes in these patients.

We have previously reported that oral biofilms in clinically healthy smokers are pathogen-rich, and that this enrichment occurs within 24 h of biofilm formation. The present investigation aimed to identify a mechanism by which smoking creates this altered community structure. By combining in vitro microbial–mucosal interface models of commensal (consisting of Streptococcus oralis, Streptococcus sanguis, Streptococcus mitis, Actinomyces naeslundii, Neisseria mucosa and Veillonella parvula) and pathogen-rich (comprising S.oralis, S.sanguis, S.mitis, A.naeslundii, N.mucosa and V.parvula, Fusobacterium nucleatum, Porphyromonas gingivalis, Filifactor alocis, Dialister pneumosintes, Selenonomas sputigena, Selenominas noxia, Catonella morbi, Parvimonas micra and Tannerella forsythia) communities with metatranscriptomics, targeted proteomics and fluorescent microscopy, we demonstrate that smoke exposure significantly downregulates essential metabolic functions within commensal biofilms, while significantly increasing expression of virulence genes, notably lipopolysaccharide (LPS), flagella and capsule synthesis. By contrast, in pathogen-rich biofilms several metabolic pathways were over-expressed in response to smoke exposure. Under smoke-rich conditions, epithelial cells mounted an early and amplified pro-inflammatory and oxidative stress response to these virulence-enhanced commensal biofilms, and a muted early response to pathogen-rich biofilms. Commensal biofilms also demonstrated early and widespread cell death. Similar results were observed when smoke-free epithelial cells were challenged with smoke-conditioned biofilms, but not vice versa. In conclusion, our data suggest that smoke-induced transcriptional shifts in commensal biofilms triggers a florid pro-inflammatory response, leading to early commensal death, which may preclude niche saturation by these beneficial organisms. The cytokine-rich, pro-oxidant, anaerobic environment sustains inflammophilic bacteria, and, in the absence of commensal antagonism, may promote the creation of pathogen-rich biofilms in smokers., Tobacco: How smoking promotes harmful biofilms Tobacco smoke inhibits the metabolism of beneficial bacteria in biofilms, while activating specific genes in pathogenic bacteria. This suggests a mechanism to explain how smoking quickly leads to the formation of damaging biofilms in the mouth and respiratory tract. Purnima Kumar and colleagues at Ohio State University, USA studied the effect of tobacco smoke on cultured biofilms used to model those that form on mucous membranes. They detected specific and varied changes in the activity of genes, proteins and metabolism that allowed pathogenic bacteria to displace beneficial “commensal” bacteria. The research suggests the transition toward pathogen-rich biofilms may contribute to the health effects of smoking by causing increased inflammation of mucous membranes and the production of damaging oxidant chemicals. Further research should investigate the chemical constituents of smoke responsible for these effects.

Background Cases of infective endocarditis (IE) require prompt etiological diagnosis for effective treatment. Molecular methods can aid in rapid and reliable diagnosis of culture-negative IE cases. We evaluated the utility of 16S rDNA PCR and sequencing in determining the causative agents of IE in valve tissues, especially when specimens were obtained after initiation of antimicrobial therapy. Methods We performed 16S rDNA PCR and sequencing in heart valve specimens and medical records review of 80 patients who underwent protocol-based cardiac surgery from 2013 to 2015. One patient did not meet the criteria for IE. Sixty-five (81.3%) and 14 pa-tients (17.5%) were diagnosed as having definite IE and possible IE, respectively. Blood and heart valve biopsy tissue were examined by using routine microbiological methods. Results Blood cultures in our hospital were IE-positive for 33 patients (41.8%), whereas 49 patients (62.0%) showed positive blood cultures when initial blood cultures performed at the referring hospital were included. Eighteen (22.8%) and 40 patients (50.6%) were IE-positive in valve tissue cultures and 16S rDNA PCR, respectively. Bacteria in the Streptococcus mitis group (n=26) were the most common etiological agents of IE. Eight (10.1%) culture-negative specimens tested positive by 16S rDNA PCR. In five of eight PCR-positive and culture-negative cases, fastidious or anaerobic organisms were the cause of IE. Conclusions Direct 16S rDNA PCR and sequencing can be used as a supplementary method to conventional blood and biopsy culture testing, especially in culture-negative IE cases that are negative for IE by culture.

Objective Compact-structured oral biofilm accumulates acids that upon prolonged exposure to tooth surface, causes demineralisation of enamel. This study aimed to assess the effect of alternative sweeteners Equal Stevia ® , Tropicana Slim ® , Pal Sweet ® and xylitol on the matrix-forming activity of plaque biofilm at both the early and established stages of formation. Methods Saliva-coated glass beads (sGB) were used as substratum for the adhesion of a mixed-bacterial suspension of Streptococcus mutans, Streptococcus sanguinis and Streptococcus mitis. Biofilms formed on sGB at 3 h and 24 h represented the early and established-plaque models. The biofilms were exposed to three doses of the sweeteners (10%), introduced at three intervals to simulate the exposure of dental plaque to sugar during three consecutive food intakes. The treated sGB were (i) examined under the SEM and (ii) collected for turbidity reading. The absorbance indicated the amount of plaque mass produced. Analysis was performed comparative to sucrose as control. Results Higher rate of bacterial adherence was determined during the early compared to established phases of formation. Comparative to the sweeteners, sucrose showed a 40% increase in bacterial adherence and produced 70% more plaque-mass. Bacterial counts and SEM micrographs exhibited absence of matrix in all the sweetener-treated biofilms at the early phase of formation. At the established phase, presence of matrix was detected but at significantly lower degree compared to sucrose (p Conclusion Alternatives sweeteners promoted the formation of oral biofilm with lighter mass and lower bacterial adherence. Hence, suggesting alternative sweeteners as potential antiplaque agents.

Objectives To report the linezolid activity, resistance mechanisms and epidemiological typing of selected isolates observed during the 2016 Zyvox® Annual Appraisal of Potency and Spectrum (ZAAPS) programme. Methods A total of 8325 organisms were consecutively collected from 76 centres in 42 countries (excluding the USA). Broth microdilution susceptibility testing was performed and isolates displaying linezolid MICs of ≥4 mg/L were molecularly characterized. Results Linezolid inhibited 99.8% of all Gram-positive pathogens at the respective susceptible breakpoints and showed a modal MIC of 1 mg/L, except for CoNS, for which the modal MIC result was 0.5 mg/L. Among isolates displaying linezolid MICs of ≥4 mg/L, one Staphylococcus aureus (linezolid MIC of 4 mg/L) harboured cfr and belonged to ST72, while four CoNS (MICs of 16-32 mg/L; ST2) showed drug target alterations. Two Enterococcus faecium (ST117) from a single site in Rome were linezolid non-susceptible (MICs of 8 mg/L) and had G2576T mutations. Eight linezolid-non-susceptible Enterococcus faecalis (MICs of 4 mg/L; 4 sites in 4 countries; ST256, ST480, ST766 and ST775) carried optrA and isolates carrying optrA from the same medical centre were genetically related. One Streptococcus gallolyticus (MIC of 4 mg/L) and one Streptococcus mitis (MIC of 16 mg/L) carried optrA and G2576T mutations, respectively. Conclusions These results document the continued long-term in vitro potency of linezolid. Alterations in the 23S rRNA and/or L3/L4 proteins remain the main oxazolidinone resistance mechanisms in E. faecium and CoNS, whereas optrA emerged as the sole mechanism in E. faecalis. Surveillance and infection control will be important strategies to detect optrA and prevent it from disseminating.

Objectives: Among viridans group streptococcal infective endocarditis (IE), the Streptococcus mitis group is the most common aetiological organism. Treatment of IE caused by the S. mitis group is challenging due to the high frequency of β-lactam resistance, drug allergy and intolerability of mainstay antimicrobial agents such as vancomycin or gentamicin. Daptomycin has been suggested as an alternative therapeutic option in these scenarios based on its excellent susceptibility profile against S. mitis group strains. However, the propensity of many S. mitis group strains to rapidly evolve stable, high-level daptomycin resistance potentially limits this approach. Methods: We evaluated the activity of 6 mg/kg/day daptomycin alone or in combination with gentamicin, ceftriaxone or ceftaroline against two daptomycin-susceptible S. mitis group strains over 96 h in a pharmacokinetic/pharmacodynamic model of simulated endocardial vegetations. Results: Daptomycin alone was not bactericidal and high-level daptomycin resistance evolved at 96 h in both organisms. Combinations of daptomycin + ceftriaxone and daptomycin + ceftaroline demonstrated enhanced killing activity compared with each antibiotic alone and prevented emergence of daptomycin resistance at 96 h. Use of gentamicin as an adjunctive agent neither improved the efficacy of daptomycin nor prevented the development of daptomycin resistance. Conclusions: Addition of ceftriaxone or ceftaroline to daptomycin improves the bactericidal activity against S. mitis group strains and prevents daptomycin resistance emergence. Further investigation with combinations of daptomycin and β-lactams in a large number of strains is warranted to fully elucidate the clinical implications of such combinations for treatment of S. mitis group IE.

Azadirachta indica A. Juss, known as neem (Meliacea family), has insecticide and pesticide properties, and many studies have shown their efficacy as antifungal, anti-inflammatory, among others. Studies for the development of drugs from plants are rising due to several factors such as bacterial resistance, indiscriminate use and the adverse reactions of antibiotics. In this study, phytochemical triage and thin layer chromatography analysis were performed, with similar results as the presence of flavonoids, tannins and terpenes. The antimicrobial activity showed that the ethyl acetate extract and butanol fraction presented greater activity against Streptococcus mutans and Streptococcus mitis presenting a MIC = 50 µg/ml for these strains, and the strain Enteroccocus faecalis, the hydroethanolic extract and aqueous fraction were most promising samples with a MIC = 50 µg/ml and MIC = 25 µg/ml, respectively. Therefore, it encourages the continuation of studies, aiming at the development of cosmetics or toothpaste. Key words: Antimicrobial activity, Azadirachta indica, minimum inhibitory concentration, oral strains, phytochemistry.

This study reports on the chemical composition and antimicrobial activity of the essential oil from Artemisia absinthium L. leaves AA EO collected in Brazil against a representative panel of cariogenic bacteria. The minimum inhibitory concentrations MICs were determined by the broth dilution method in 96-well microplates. AA EO was inactive against most of the investigated oral pathogens, but it displayed moderate activity against Streptococcus mutans MIC = 250 μg/mL and very promising activity against Streptococcus mitis MIC = 62.5 μg/mL. Gas chromatography GC FID and gas chromatography mass spectrometry GC-MS revealed that camphor 1, 19.0 %, E-caryophyllene 2, 9.3 %, eucalyptol 3, 6.8 %, germacrene D 6.7 %, and α-cadinol 6.5 % were the major chemical constituents of AA EO. However, when tested alone, compounds 1, 2, and 3 were inactive MIC > 1000 μg/mL against all the studied microorganisms.