Advancements in Chitosan-Based Nanoparticles for Pulmonary Drug Delivery.

The evolution of respiratory diseases represents a considerable public health challenge, as they are among the leading causes of death worldwide. In this sense, in addition to the high prevalence of diseases such as asthma, chronic obstructive pulmonary disease, pneumonia, cystic fibrosis, and lung cancer, emerging respiratory diseases, particularly those caused by members of the coronavirus family, have contributed to a significant number of deaths on a global scale over the last two decades. Therefore, several studies have been conducted to optimize the efficacy of treatments against these diseases, focusing on pulmonary drug delivery using nanomedicine. Thus, the development of nanocarriers has emerged as a promising alternative to overcome the limitations of conventional therapy, by increasing drug bioavailability at the target site and reducing unwanted side effects. In this context, nanoparticles composed of chitosan (CS) show advantages over other nanocarriers because chitosan possesses intrinsic biological properties, such as anti-inflammatory, antimicrobial, and mucoadhesive capacity. Moreover, CS nanoparticles have the potential to enhance drug stability, prolong the duration of action, improve drug targeting, control drug release, optimize dissolution of poorly soluble drugs, and increase cell membrane permeability of hydrophobic drugs. These properties could optimize the performance of the drug after its pulmonary administration. Therefore, this review aims to discuss the potential of chitosan nanoparticles for pulmonary drug delivery, highlighting how their biological properties can improve the treatment of pulmonary diseases, including their synergistic action with the encapsulated drug.

Biocompatibilidade em pulpotomia de dentes decíduos: melhor material e alternativas ao uso do MTA: revisão sistemática e meta-análise / Biocompatibility in pulpotomy in deciduous teeth: best material and alternatives to MTA use: a systematic review and meta-analysis

Introdução: A terapia pulpar vital é o tratamento que visa a manutenção da vitalidade pulpar e da função do dente. Para a pulpotomia, os materiais são escolhidos baseados em algumas características fundamentais, tais como a biocompatibilidade e bioatividade. Atualmente, o Agregado de Trióxido Mineral (MTA) é o mais comumente utilizado para este procedimento. Objetivo: Identificar o melhor material para uso em pulpotomia em dentes decíduos considerando a propriedade de biocompatibilidade, através de revisão sistemática da literatura e metanálise. Material e Métodos: A pergunta norteadora foi: "Qual é o melhor agente para pulpotomia em termos de biocompatibilidade?". Foi realizada pesquisa nas bases de dados eletrônicas Medline/PubMed, SciELO, LILACS e Web of Science sem restrição de data inicial até outubro de 2020, usando os seguintes descritores padronizados pelo Medical Subject Headings (MeSH): "pulpotomy", "pulp therapy", "biomaterials", "biocompatible materials", "pulp capping agent", "pulp capping materials".Resultados: Um total de 358 estudos foram identificados, sendo 15 deles selecionados para análise qualitativa e seis para metanálise. A revisão avaliou aspectos clínicos, radiográficos e histológicos, considerando diferentes períodos de acompanhamento, amostras e metodologias. Diversos materiais foram encontrados e o MTA foi o mais frequente. Embora os resultados qualitativos tenham sido pouco conclusivos em relação ao melhor deles, foi possível estabelecer que o Cimento Portland é uma alternativa viável para a substituição do MTA. Conclusão: A metanálise demonstrou que o MTA é o material mais favorável para uso em pulpotomias em dentes decíduos.

Introduction: Vital pulp therapy is the treatment aimed at maintaining pulp vitality and tooth function. For pulpotomy, materials are chosen based on some fundamental characteristics, such as biocompatibility and bioactivity. Currently, Mineral Trioxide Aggregate (MTA) is the most commonly used for this procedure. Objective: To identify the best material for use in pulpotomy in deciduous teeth considering the property of biocompatibility, through a systematic review of the literature and meta-analysis. Materials and Methods: The guiding question was: "What is the best agent for pulpotomy considering the biocompatibility property?". A search was performed in the electronic databases MEDLINE/PubMed, SciELO, LILACS and Web of Science without an initial date until October 2020, using the following descriptors recognized by Medical Subject Headings (MeSH): "pulpotomy", "pulp therapy", "biomaterials", "biocompatible materials'', "pulp capping agent", "pulp capping materials". Results: A total of 358 studies were identified, 15 of them selected to qualitative analysis and six to meta-analysis. The revision evaluated clinical, radiographic and histological aspects, considering different follow-up periods, samples and methodologies. Several materials were found and MTA was the most frequent. Although the qualitative results were inconclusive in relation to the best of them, it was possible to establish that the Portland Cement is a viable alternative for MTA replacement. Conclusion: The meta-analysis demonstrated that MTA is the most favorable material for use in pulpotomies in deciduous teeth.

Maintenance of sterility in SMS packaging in dental environments: concern with biosafety

Healthcare services must be guided by biosafety practices and microbial control. This control is highly influenced by humidity, which directly impacts the maintenance of sterility of the materials used in the appointments. High concentration of moisture, in the form of aerosol, splashes and spills, is caused during dental care. During the COVID-19 times the contamination by aerosol and droplets worries greatly. Considering that it could cause harm to the sterility of an autoclaved material, especially in dental environments, the objective was to evaluate the behavior of SMS sterilization packages (Spunbonded / Meltblown / Spunbonded) against microbial penetration in an aqueous vehicle. SMS of three brands were challenged, equally divided into two groups: virgin and processed (subjected to a single autoclaving cycle). Each specimen was aseptically deposited on Macconkey agar. Subsequently, 5 µL of Escherichia coliATCC 25922 saline solution [108CFU mL-1] was deposited in center of the SMS specimen and the dish incubated at36°C/ 48h. Reading was performed by the presence or absence of bacterial growth typical of the species under the SMS, observed on the back of Petri dish. The lowest penetration rate observed was 60% for one of the brands in the virgin condition, and 75% for two brands in the processed condition. Statistical analysis showed an association between bacterial penetration and the evaluated group, this association being valid only in the virgin condition. The different SMS behave similarly in terms of resistance to bacterial penetration after being processed. The data show that moisture can assist in bacterial transport through sterilized SMS. Therefore, SMS packages are not able to prevent bacterial penetration, and possibly other microorganisms, when in aqueous vehicles, offering a potential risk of breaking the aseptic chain. Thus, care must be taken in routines for handling and storage sterile packaging.

Impacto da pandemia de COVID-19 no ensino odontológico em instituições brasileiras: uma revisão integrativa / Impact of the COVID-19 pandemic on dental education in Brazilian institutions: An integrative review

A disseminação do Sars-CoV-2, agenteetiológicoda COVID-19, se tornou um problema de saúde pública de importância internacional. Dentre as medidas para conter seu espraiamento, está asuspensão das aulas em instituições de ensino.Assim, esta revisão integrativa objetiva apresentar um panorama sobre o impacto da pandemia no ensino da Odontologia nas instituições brasileiras.Foram realizadas buscas nas bases de dados Medline, LILACS e SciELO, utilizando-se descritores nas línguas inglesa e portuguesa. Foram recuperados 60 estudos, sendo 17 elegíveis para leitura integral. Destes, 4 estudos atenderam aos critérios de inclusão e exclusão. Observou-se que o modelo de Ensino Remoto Emergencial (ERE) por meio de ferramentas digitaisfoi a estratégia de ensino não presencial mais utilizada nas instituições brasileiras. O ERE permitiu que o impacto da pandemia de COVID-19 fosse sentido de maneira mais branda pela comunidade acadêmica brasileira, engajando alunos e diminuindo a ansiedade de alunos e professores. Por outro lado, a infraestrutura tecnológica deficiente no Brasil contribuiu para a dificuldade em substituir as atividades clínicas. Fato ainda exacerbado pela dificuldade de adequação da infraestrutura física das instituições durante o planejamento de retorno às atividades presenciais. Apesar de todas as estratégias de superação, desempenhadas pelas instituições brasileiras de ensino odontológico, estas não foram refletidas em literatura científica nas bases de dados indexadas.Assim, enfatiza-se a necessidade de trabalhos sobre esta temática, para que seja possível disseminar as experiências vividas durante o período pandêmico (AU).

The spread of SARS-CoV-2, the etiological agent of COVID-19, has become a public health problem of international importance. Among the measures to curb its spread is the suspension of classes in educational institutions. Thus, this integrative review aims to provide an overview of the impact of the pandemic on dentistry education in Brazilian institutions. The Medline, LILACS and SciELO databases were searched using descriptors in English and Portuguese.A total of 60 studies were retrieved, with17eligible for full reading. Of these, 4 studies met the inclusion and exclusion criteria. It was observed that the emergency remote education (ERE) model through digital tools was the most used remoteteaching strategy in Brazilian institutions. ERE allowed the impact of the COVID-19 pandemic to be felt more mildly by the Brazilian academic community, better engaging students and reducing the anxiety of students and teachers. On the other hand, the deficient technological infrastructure in Brazil contributed to difficulty inreplacing clinical activities. This fact is further exacerbated by the difficulty of adapting the physical infrastructure of the institutions whenplanning to returnto in-personactivities. Despite numerousstrategies employedby Brazilian dental education institutions, theywere not reflected in the scientific literature in the indexed databases.Thus, there is aneed for studies on this topic so that it is possible to disseminate the experiences lived during the pandemic period (AU).

Analysis of Chlorhexidine Modified Cement in Orthodontic Patients: A Double-Blinded, Randomized, Controlled Trial.

OBJECTIVES: The aim of this study was to evaluate the microbiological and mechanical properties of glass ionomer cement (GIC) modified by chlorhexidine (CLX) for the purpose of cementing bands to the teeth of orthodontic patients. MATERIALS AND METHODS: Ten patients, between the ages of 19 and 33 years, in the initial stage of orthodontic treatment, were randomly designated to two groups using the split-mouth design (n = 10). One group (GICEX) had bands cemented with GIC modified by CLX and a Control group (GIC), evaluated at time intervals before (T0), 3 months (T3), and 6 months (T6) after cementation. Total microbiological counts were performed, and color stability of tooth enamel, salivary pH, and the adhesive remnant index (ARI) were evaluated. STATISTICAL ANALYSIS: The Friedman and Dunn's tests, Mann-Whitney, one-way analysis of variance, and Tukey, and paired and non-paired t-tests (p< 0.05) were used. RESULTS: In T3, there was evidence of significant reduction in the quantity of colony forming unit (CFU) in GICEX group in comparison with the Control (p = 0.041). In T6, the quantity of CFU was similar to the quantity in T3 and significantly different to control (p = 0.045); Control group demonstrated a similar quantity of CFU between the experimental time intervals (p = 0.066). Salivary pH demonstrated significant difference only between the time intervals T0 and T6 (p = 0.022). The tooth enamel color (p = 0.366) and ARI (p = 0.343) values demonstrated no significant changes. CONCLUSION: The incorporation of CLX into GIC demonstrated effective antibacterial action, allowed a good bond of the cement to the enamel, a high rate of survival of the bands, did not change the color of the tooth enamel, and maintained the salivary pH at physiological levels.

Mitracarpus frigidus (Rubiaceae) inhibits inflammatory and oxidative stress mediators in Salmonella sp. mouse infection.

OBJECTIVES: Evaluation of the in-vivo anti-inflammatory activity of the methanolic extract obtained from the aerial parts of Mitracarpus frigidus (MFM) in the infection caused by two Salmonella strains and its chemical fingerprint by UFLC-quadrupole time of flight-MS. METHODS: The efficacy of MFM was investigated in a classical in-vivo Salmonella infection mouse model. A Salmonella reference strain (ATCC 13311) and a clinical isolate were used to infect mice and then MFM was orally administered during 14 days. At the end of the treatment with MFM, the infection and inflammatory levels were assayed. KEY FINDINGS: MFM treatment showed a significant reduction in mice mortality by Salmonella infection and, also, did not cause alterations in the liver function. Inhibitions of inflammatory and oxidative stress mediators [malondialdehyde (MDA), catalase, and metalloproteinase] were possibly involved in the observed effects. Chlorogenic acid, clarinoside, quercetin-pentosylhexoside, rutin, kaempferol-3O-rutinoside, kaempferol-rhamnosylhexoside and 2-azaanthraquinone were identified in MFM. CONCLUSIONS: MFM was effective in some inflammatory parameters, in the experimental conditions that were used in the study. The results presented in this study and the previous in-vitro anti-Salmonella activity reported by our research group reinforce the importance of MFM studies to considerer it as an alternative treatment for salmonellosis.

Biosafety in Dental Practices Versus COVID-19 Outbreak

ABSTRACT Objective: To evaluate the dentists' knowledge about biosafety considering the SARS-CoV-2 and the risks of increasing the COVID-19 outbreak by dental practices during the pandemic in Brazil. Material and Methods: A cross-sectional study was performed by internet-based snowball sampling technique. A questionnaire with questions about different content was applied, and then analyzed the following two parameters: participants' Brazilian region and professional's specialty. Results: A total of 413 e-questionnaires from all Brazilian regions were considered valid. There were no significant differences among biosafety measures adopted by participants from different Brazilian regions (p≥0.05), except for those from North region, which have applied less previous oral antisepsis, temperature screening, and specific anamnesis tracking COVID-19 symptoms (p<0.05). The unique use of N95 mask was positively associated with North region (p<0.05). Expert participants of Groups 2 (oral surgery and correlate areas) and 4 (orthodontics, oral radiology and facial jaw orthopedics) were more updated than other ones (p<0.05). Conclusion: The biosafety protocols applied by participants were not adequate for the epidemiologic status of COVID-19 in each region of Brazil, from 13th May to 17th June 2020. Specialties linked to microbiology area or structured social networks have better applied preventive measures for COVID-19.

Searching for mechanisms of action of antimicrobials.

Although development of antimicrobial resistance by bacteria is a natural phenomenon, the antibiotic resistance crisis is a reality that leads us in a gap of antimicrobial alternatives on therapeutics. Considering this cruel reality and committed to contribute to look for new antibacterial agents, this manuscript presents a review of easy laboratory methods that evaluate the mode of action of compounds, since it is a basic requirement for the discovery and development of new drugs. The literature was screened by searching the keywords "mode of action", "antibiotic", "antimicrobial activity", "inhibition mode", "method" and "bacteria" in Pubmed, Scopus, Science Direct and BVS in a period of time from 2000 to 2019. This review demonstrates the wide variety of methods that can be employed in research on mechanisms of action of antibacterial substances. Therefore, we compiled different protocols (presented in the supplementary material), available in the literature, with the purpose of facilitating the start of experiments.

The Novel Coronavirus: An Alert for Pacifiers' Disinfection

Objective: To evaluate the best strategy for pacifier disinfection methods. Material and Methods: The literature search was conducted on MEDLINE/PubMed, Scielo, Lilacs, Web of Science, and Scopus databases to find all relevant articles published over the past 20 years, based on PRISMA guidelines. Two reviewers extracted data independently by using a standardized form. The following factors were recorded: country of study, type of study, pacifier material, sample number, microorganisms analyzed, decontamination methods used, method accessibility and results found. Results: A total of 121 articles were obtained from all databases. The selected documents underwent a final screening, resulting in 8 articles. The method of disinfection analyzed by the literature were: 3.5% neutral detergent, apple cider vinegar 70% spray, boiling water during 15 minutes, sodium hypochlorite 2.5, hydrogen peroxide 70% spray, chlorhexidine 0.12%, Brushtox®, sterile water and microwave. Conclusion: Because of the broad methods for pacifier disinfection and different levels of accessibility to disinfectant agents, the pacifier consensus for decontamination remains unclear. Although the disinfection methods are diverse, the methods suggested to its disinfection were identified and described in this article.

The Novel Coronavirus: An Alert for Pacifiers' Disinfection

Abstract Objective: To evaluate the best strategy for pacifier disinfection methods. Material and Methods: The literature search was conducted on MEDLINE/PubMed, Scielo, Lilacs, Web of Science, and Scopus databases to find all relevant articles published over the past 20 years, based on PRISMA guidelines. Two reviewers extracted data independently by using a standardized form. The following factors were recorded: country of study, type of study, pacifier material, sample number, microorganisms analyzed, decontamination methods used, method accessibility and results found. Results: A total of 121 articles were obtained from all databases. The selected documents underwent a final screening, resulting in 8 articles. The method of disinfection analyzed by the literature were: 3.5% neutral detergent, apple cider vinegar 70% spray, boiling water during 15 minutes, sodium hypochlorite 2.5, hydrogen peroxide 70% spray, chlorhexidine 0.12%, Brushtox®, sterile water and microwave. Conclusion: Because of the broad methods for pacifier disinfection and different levels of accessibility to disinfectant agents, the pacifier consensus for decontamination remains unclear. Although the disinfection methods are diverse, the methods suggested to its disinfection were identified and described in this article.

Bacteriocin-like inhibitory substance in aquaculture: a classic method of protein precipitation for a new aplicability / Substância inibidora tipo bacteriocina na aquicultura: método clássico de precipitação de proteínas para novas aplicações

Techniques to decrease losses from bacterial diseases are always important to improve the fish production. The use of antagonistic substances (bacteriocins) has been proven to be a viable option. The aim of this study was to evaluate different methods of purification for bacteriocin like inhibitory substances (BLIS). For the purification process, we isolated and used two Gram-positive bacilli that produce antagonistic substances for pathogens in aquaculture. Tests for detection of interfering factors were also performed. After the confirmation that the antagonistic action was due the BLIS activity, we carried out the purification methods. The methods tested were: cell free supernatant, acid extraction and ammonium sulfate precipitation at two concentrations (20 and 50%). Salmonella Tiphy CFP/IAL1472 and Aeromonas hydrophila (isolated in a tilapia production environment) were used as indicators of the efficiency of extracts in controlling pathogenic potentials. Ammonium sulfate precipitation at 50% was the most appropriate for purifying the antagonistic substance for both indicators. The extracts of the two isolates remained active for 22 days at 25ºC. These are promising results regarding the water and fish health without the use of antibiotics, in this manner being a safer environmental practice.

Técnicas para diminuir as perdas causadas por doenças bacterianas são importantes para melhorar continuamente a produção de pescado. O uso de substâncias antagônicas (bacteriocinas) tem-se mostrado uma opção viável. O objetivo do trabalho foi avaliar diferentes métodos de purificação de bacteriocinas como substâncias inibidoras (BLIS). Dois bacilos Gram-positivos, produtores de substâncias antagonistas para agentes patogênicos da aquicultura, foram utilizados em processos de purificação. Depois de confirmada a ação antagônica pela atividade de BLIS, os métodos de purificação foram realizados. Os métodos testados foram: células livres de sobrenadante, extração ácida e precipitação por sulfato de amônia em duas concentrações (20 e 50%). Salmonella Typhi PCP/IAL1472 e Aeromonas hydrophila (isolada de um ambiente de tilapicultura) foram utilizadas como indicadores de eficiência dos extratos. O precipitado por sulfato de amônio a 50% foi o mais adequado para purificar a substância antagonista para ambos os isolados indicadores. Os extratos dos dois isolados permaneceram ativos por 22 dias em 25ºC. Estes resultados são promissores do ponto de vista da manutenção da sanidade da água e dos peixes, sem uso de antibióticos, constituindo uma prática ambientalmente mais segura.

Longitudinal study on clinical and microbial analysis of periodontal status in pregnancy.

This study was aimed to provide a longitudinal overview of the subgingival bacterial microbiome using fluorescence in situ hybridization (FISH) technique, in women in the second trimester of pregnancy (between 14 and 24 weeks), and 48 h and 8 weeks postpartum. Of 31 women evaluated during pregnancy, 24 returned for the 48-h and 18 for their 8-week exams postpartum. Probing depth (PD), bleeding on probing, clinical attachment level, and presence of calculus were recorded. Subgingival plaque samples were collected, and FISH was used to identify the numbers of eight periodontal pathogens. Friedman test was used to compare differences between follow-up examinations, followed by a multiple comparison test for a post hoc pairwise comparison. Clinically, a significantly greater number of teeth with PD = 4-5 mm were found during pregnancy than on postpartum examinations. Microbial analysis showed a statistically significant decrease in cell count over the study period for Prevotella nigrescens. P. intermedia, Campylobacter rectus, and Porphyromonas gingivalis also decrease, although not significantly, and Aggregatibacter actinomycetemcomitans increased. No significant changes were found for Fusobacterium nucleatum, Treponema denticola, or Tannerella forsythia. Our data demonstrate a change in the subgingival microbiota during pregnancy, at least for P. nigrescens.

Longitudinal study on clinical and microbial analysis of periodontal status in pregnancy

Abstract This study was aimed to provide a longitudinal overview of the subgingival bacterial microbiome using fluorescence in situ hybridization (FISH) technique, in women in the second trimester of pregnancy (between 14 and 24 weeks), and 48 h and 8 weeks postpartum. Of 31 women evaluated during pregnancy, 24 returned for the 48-h and 18 for their 8-week exams postpartum. Probing depth (PD), bleeding on probing, clinical attachment level, and presence of calculus were recorded. Subgingival plaque samples were collected, and FISH was used to identify the numbers of eight periodontal pathogens. Friedman test was used to compare differences between follow-up examinations, followed by a multiple comparison test for a post hoc pairwise comparison. Clinically, a significantly greater number of teeth with PD = 4-5 mm were found during pregnancy than on postpartum examinations. Microbial analysis showed a statistically significant decrease in cell count over the study period for Prevotella nigrescens. P. intermedia, Campylobacter rectus, and Porphyromonas gingivalis also decrease, although not significantly, and Aggregatibacter actinomycetemcomitans increased. No significant changes were found for Fusobacterium nucleatum, Treponema denticola, or Tannerella forsythia. Our data demonstrate a change in the subgingival microbiota during pregnancy, at least for P. nigrescens.

Antagonistic activity expressed by Shigella sonnei: identification of a putative new bacteriocin.

Bacteriocins are antibacterial, proteinaceous substances that mediate microbial dynamics. Bacteriocin production is a highly disseminated property among all major lineages of bacteria, including Shigella. In this paper, we addressed the purification and characterisation of a bacteriocin produced by a Shigella sonnei strain (SS9) isolated from a child with acute diarrhoea. The substance was purified through ammonium-sulphate precipitation and sequential steps of chromatography. The intracellular fraction obtained at 75% ammonium sulphate maintained activity following exposure to pH values from 1-11 and storage at -80ºC for more than two years and was inactivated by high temperatures and proteases. The molecular mass of the purified bacteriocin was determined by mass spectrometry to be 18.56 kDa. The N-terminal sequence of the bacteriocin did not match any other antibacterial proteins described. A putative new bacteriocin produced by S. sonnei has been detected. This bacteriocin may represent a newly described protein or a previously described protein with a newly detected function. Considering that SS9 expresses antagonism against other diarrhoeagenic bacteria, the bacteriocin may contribute to S. sonnei virulence and is potentially applicable to either preventing or controlling diarrhoeal disease.

Antagonistic activity expressed by Shigella sonnei: identification of a putative new bacteriocin

Bacteriocins are antibacterial, proteinaceous substances that mediate microbial dynamics. Bacteriocin production is a highly disseminated property among all major lineages of bacteria, including Shigella. In this paper, we addressed the purification and characterisation of a bacteriocin produced by a Shigella sonnei strain (SS9) isolated from a child with acute diarrhoea. The substance was purified through ammonium-sulphate precipitation and sequential steps of chromatography. The intracellular fraction obtained at 75% ammonium sulphate maintained activity following exposure to pH values from 1-11 and storage at -80ºC for more than two years and was inactivated by high temperatures and proteases. The molecular mass of the purified bacteriocin was determined by mass spectrometry to be 18.56 kDa. The N-terminal sequence of the bacteriocin did not match any other antibacterial proteins described. A putative new bacteriocin produced by S. sonnei has been detected. This bacteriocin may represent a newly described protein or a previously described protein with a newly detected function. Considering that SS9 expresses antagonism against other diarrhoeagenic bacteria, the bacteriocin may contribute to S. sonnei virulence and is potentially applicable to either preventing or controlling diarrhoeal disease.

Proteomic analysis of Escherichia coli with experimentally induced resistance to piperacillin/tazobactam.

The worldwide emergence of antibiotic-resistant bacteria poses a serious threat to human health. In addition to the difficulties in controlling infectious diseases, the phenotype of resistance can generate metabolic changes which, in turn, can interfere with host-pathogen interactions. The aim of the present study was to identify changes in the subproteome of a laboratory-derived piperacillin/tazobactam-resistant strain of Escherichia coli (minimal inhibitory concentration [MIC] = 128 mg/L) as compared with its susceptible wild-type strain E. coli ATCC 25922 (MIC = 2 mg/L) using 2-D fluorescence difference gel electrophoresis (2D-DIGE) followed by matrix-assisted laser desorption/ionization time-of-flight/time-of-flight (MALDI-TOF/TOF MS). In the resistant strain, a total of 12 protein species were increased in abundance relative to the wild-type strain, including those related to bacterial virulence, antibiotic resistance and DNA protection during stress. Fourteen proteins were increased in abundance in the wild-type strain compared to the resistant strain, including those involved in glycolysis, protein biosynthesis, pentose-phosphate shunt, amino acid transport, cell division and oxidative stress response. In conclusion, our data show overall changes in the subproteome of the piperacillin/tazobactam-resistant strain, reporting for the first time the potential role of a multidrug efflux pump system in E. coli resistance to piperacillin/tazobactam.

Bacteriocin production by Shigella sonnei isolated from faeces of children with acute diarrhoea.

Shigella is a common agent of diarrhoea, a worldwide major health problem. The bacterium produces bacteriocins; however, the role of these substances as a virulence factor is completely unknown. With the aim to search for colicin production by Shigella sonnei, to evaluate the influence of culture conditions on bacteriocin expression, and to characterize the substance partially, 16 S. sonnei strains isolated from children with diarrhoea were tested for antagonism against members of the intestinal microbiota or agents of diarrhoea. Nine strains exhibited isoantagonism and heteroantagonism against S. flexneri and diarrhoeagenic Escherichia coli. Autoantagonism and antagonism against the intestinal microbiota were not detected. Culture medium and incubation conditions influenced antagonism expression. Antagonism resulting from bacteriophages, low pH, fatty acids, hydrogen peroxide, and chloroform was excluded. The activity of the intracellular fraction obtained with 75% ammonium sulphate was preserved at pH 1.0-11.0, and was found to be reduced by organic solvents and affected by high temperatures and proteases. The antagonistic spectrum and the in vitro conditions for better antagonism expression suggest that the role of colicin in S. sonnei virulence, if any, would be expressed prior to infection, and may regulate population density of enteropathogens by helping in organism transmission.

Actinomycetemcomitin: a new bacteriocin produced by Aggregatibacter (Actinobacillus) actinomycetemcomitans.

Aggregatibacter (Actinobacillus) actinomycetemcomitans P(7-20) strain isolated from a periodontally diseased patient has produced a bacteriocin (named as actinomycetemcomitin) that is active against Peptostreptococcus anaerobius ATCC 27337. Actinomycetemcomitin was produced during exponential and stationary growth phases, and its amount decreased until it disappeared during the decline growth phase. It was purified by ammonium sulphate precipitation (30-60% saturation), and further by FPLC (mono-Q ionic exchange and Phenyl Superose hydrophobic interaction) and HPLC (C-18 reversed-phase). This bacteriocin loses its activity after incubation at a pH below 7.0 or above 8.0, following heating for 30 min at 45 degrees C, and after treatment with proteolytic enzymes such as trypsin, alpha-chymotrypsin, and papain. Actinomycetemcomitin has a molecular mass of 20.3 KDa and it represents a new bacteriocin from A. actinomycetemcomitans.