Shortened derivatives from native antimicrobial peptide LyeTx I: In vitro and in vivo biological activity assessment.

In the continuing search for novel antibiotics, antimicrobial peptides are promising molecules, due to different mechanisms of action compared to classic antibiotics and to their selectivity for interaction with microorganism cells rather than with mammalian cells. Previously, our research group has isolated the antimicrobial peptide LyeTx I from the venom of the spider Lycosa erythrognatha. Here, we proposed to synthesize three novel shortened derivatives from LyeTx I (LyeTx I mn; LyeTx I mnΔK; LyeTx I mnΔKAc) and to evaluate their toxicity and biological activity as potential antimicrobial agents. Peptides were synthetized by Fmoc strategy and circular dichroism analysis was performed, showing that the three novel shortened derivatives may present membranolytic activity, like the original LyeTx I, once they folded as an alpha helix in 2.2.2-trifluorethanol and sodium dodecyl sulfate. In vitro assays revealed that the shortened derivative LyeTx I mnΔK presents the best score between antimicrobial (↓ MIC) and hemolytic (↑ EC50) activities among the synthetized shortened derivatives, and LUHMES cell-based NeuriTox test showed that it is less neurotoxic than the original LyeTx I (EC50 [LyeTx I mnΔK] ⋙ EC50 [LyeTx I]). In vivo data, obtained in a mouse model of septic arthritis induced by Staphylococcus aureus, showed that LyeTx I mnΔK is able to reduce infection, as demonstrated by bacterial recovery assay (∼10-fold reduction) and scintigraphic imaging (less technetium-99m labeled-Ceftizoxime uptake by infectious site). Infection reduction led to inflammatory process and pain decreases, as shown by immune cells recruitment reduction and threshold nociception increment, when compared to positive control group. Therefore, among the three shortened peptide derivatives, LyeTx I mnΔK is the best candidate as antimicrobial agent, due to its smaller amino acid sequence and toxicity, and its greater biological activity.

Enzymatic detergent reuse in gastroscope processing: a potential source of microorganism transmission.

OBJECTIVE: to evaluate the potential contamination of enzymatic detergent from its reuse and to identify the microbiological profile in the solution used to clean gastrointestinal endoscopic devices. METHOD: cross-sectional study based on microbiological analysis of 76 aliquots of 19 different enzymatic detergent solutions used to clean endoscopic devices. The aliquots were homogenized, subjected to Millipore® 0.45 µm membrane filtration and the presumptive identification of microorganisms was performed by biochemical-physiological methods according to previously established specific bacterial groups that are of clinical and epidemiological relevance. RESULTS: the mean values, as well as the standard deviation and the median, of the enzymatic detergent microbial load increased as the solution was reused. There was a significant difference between the means of after first use and after fifth reuse. A total of 97 microorganisms were identified, with predominance of the coagulase-negative Staphylococcus, Pseudomonas spp., Klebsiella spp., Enterobacter spp. genus, and Escherichia coli species. CONCLUSION: the reuse of the enzymatic detergent solution is a risk to the safe processing of endoscopic devices, evidenced by its contamination with pathogenic potential microorganisms, since the enzymatic detergent has no bactericidal property and can contribute as an important source for outbreaks in patients under such procedures.

Pattern of Disinfection of Root Canal Dentin by Alternated Acid-Base Irrigating Regimen.

OBJECTIVE: To quantify Enterococcus faecalis density in root canal dentin after chemomechanical preparation (CMP) using alternated irrigating regimen. METHODOLOGY: Root canals (RC) were contaminated with E. faecalis (ATCC 19433) for 3 weeks and evident biofilms were obtained. After initial sampling (S1), the CMP was aided by irrigants: saline solution (control; n=12), a conventional regimen (CR) (group 1; n=12) using 5.25% NaOCl and a final rinse with 17% EDTA, and an alternating regimen (AR) of intercalated use of NaOCl and EDTA (group 2, n=12), followed by a second sampling (S2). After 2 weeks, S3 was obtained. Two roots were analyzed by scanning electron microscopy. Each root was divided into cervical, mild, and apical segments and sampling of the superficial (n=90) and deep (n=90) dentin layers was obtained using Gates-Glidden burs. The E. faecalis density (CFU/mg) in log10 was categorized as residual (0 > 0.2), moderate (0.2 ≥ 0.5), or elevated (> 0.5). The prevalence of positive samples in BHI and BHI-A was analyzed by Pearson's chi-square test. The data were normalized by a log10 transformation of CFU and were analyzed by one-way ANOVA and Tukey's tests. RESULTS: Biofilms were observed only in the control root canal walls. Topographically, the controls and CR showed similar distributions of E. faecalis in the dentin. Microbiologically positive root canals harbored much E. faecalis in the adjacent dentin (p < 0.05). Irrigating saline provided moderate density of E. faecalis in the dentin while CR and AR resulted in a residual density of microorganisms (p < 0.05). CONCLUSIONS: The Enterococcus faecalis density in dentin was influenced by the irrigating regimen and the microbiological status of the root canal. The CMP aided by the alternating regimen interfered with the recolonization of the root canal and topographic distribution of Enterococcus in root dentin.

Knowledge, behaviour and microbial load of workers handling dental solid waste in a public health service in Brazil.

Healthcare wastes are those generated inside healthcare services, including dental clinics. Workers coming into close proximity to hazardous healthcare waste are potentially at risk. In an attempt to assess the knowledge and attitudes of workers dealing with infectious waste, a questionnaire was administered. The biological risk was investigated by evaluating the microbial load and screening some clinically relevant micro-organisms in the nasal mucosa, hands and coats of these workers. The results showed that 66.6% of the study population had incomplete primary education. Only two workers have had their blood tested to confirm anti-HBs levels. Microbial load evaluation on hand surfaces of morning workers showed statistically significant lower microbial loads after the workday when compared with the beginning of the work period. It is important to highlight that some clinically relevant bacteria, such as Pseudomonas aeruginosa and Klebsiella pneumoniae were isolated from worker's hands. This study revealed the need for more training programmes regarding awareness of safe waste disposal protocols and also the necessity of discussing vaccination and its implications. Data regarding microbial loads of the worker's hands, mostly at the beginning of the workday when handwashing is recommended worldwide, emphasise that hygiene measures should receive more attention during training exercises.

Evaluation of polymeric PLGA nanoparticles conjugated to curcumin for use in aPDT

ABSTRACT Antimicrobial photodynamic therapy (aPDT) involves the association of a photosensitizing agent with a light source with the goal of causing apoptosis or microbial lysing. The use of compounds with natural active principles is gaining prominence throughout the world. Several studies from groups that are linked to the development of innovations in the pharmaceutical market have used natural dyes, such as curcumin, the efficacy of which has been demonstrated in aPDT trials. Difficulties related to physicochemical stability, solubility and cell penetration are some of the challenges associated with this field. The present work aimed to prepare, investigate the characteristics and improve the photodynamic activity of PLGA-based nanoparticles loaded with curcumin for use in aPDT therapy. Using the simple technique of emulsion during the evaporation of a solvent, the particles were built, characterized and tested against microorganisms with importance for medicine and dentistry. The results revealed that the particles were able to protect the curcumin against degradation and eliminate some microorganism species at nanomolar concentrations.

Murine Experimental Root Canal Infection: Cytokine Expression in Response to F. nucleatum and E. faecalis.

The aim of this study was to evaluate the gene expression of proinflammatory (RANKL, TNF-a and IFN-g) and regulatory (TGF-b and IL-10) cytokines as reaction to experimental infection by mono or bi-association of Fusobacterium nucleatum (ATCC 10953) and Enterococcus faecalis (ATCC 19433). F. nucleatum and E. faecalis, either in mono- or bi-association were inoculated into the root canal system (RCS) of Balb/c mice. Animals were sacrificed at 10 and 20 days after infection and periapical tissues surrounding the root were collected. The mRNA expression of the cytokines RANKL, TNF-a, IFN- g, TGF-b and IL-10 was assessed using real-time PCR. The Kruskal-Wallis test was used for statistical analysis. F. nucleatum mono-infection induced high expression of RANKL and TNF-a, while its modulation was due to IL-10. High expression of IFN-g at day 20 was up-regulated by E. faecalis and RANKL; TNF-a was up-regulated by an independent mechanism via IL-10 and TGF-b. Bi-association (F. nucleatum and E. faecalis) stimulated high expression of RANKL, TNF-a and IFN-g, which seemed to be modulated by TGF-b 20 days later. The gene expression of proinflammatory cytokines was more prominent in the earlier periods of the experimental periapical infection, which concomitantly decreased in the later period. This expression may be regulated by IL-10 and TGF-b in an infection-specific condition.

Murine Experimental Root Canal Infection: Cytokine Expression in Response to F. nucleatum and E. faecalis

Abstract The aim of this study was to evaluate the gene expression of proinflammatory (RANKL, TNF-a and IFN-g) and regulatory (TGF-b and IL-10) cytokines as reaction to experimental infection by mono or bi-association of Fusobacterium nucleatum (ATCC 10953) and Enterococcus faecalis (ATCC 19433). F. nucleatum and E. faecalis, either in mono- or bi-association were inoculated into the root canal system (RCS) of Balb/c mice. Animals were sacrificed at 10 and 20 days after infection and periapical tissues surrounding the root were collected. The mRNA expression of the cytokines RANKL, TNF-a, IFN- g, TGF-b and IL-10 was assessed using real-time PCR. The Kruskal-Wallis test was used for statistical analysis. F. nucleatum mono-infection induced high expression of RANKL and TNF-a, while its modulation was due to IL-10. High expression of IFN-g at day 20 was up-regulated by E. faecalis and RANKL; TNF-a was up-regulated by an independent mechanism via IL-10 and TGF-b. Bi-association (F. nucleatum and E. faecalis) stimulated high expression of RANKL, TNF-a and IFN-g, which seemed to be modulated by TGF-b 20 days later. The gene expression of proinflammatory cytokines was more prominent in the earlier periods of the experimental periapical infection, which concomitantly decreased in the later period. This expression may be regulated by IL-10 and TGF-b in an infection-specific condition

Resumo O objetivo deste trabalho foi avaliar a expressão gênica de citocinas pró-inflamatórias (RANKL, TNF-a e IFN-g) e regulatórias (TGF-b e IL-10) em resposta à infecção experimental por Fusobacterium nucleatum (ATCC 10953) e Enterococcus faecalis (ATCC 19433) como mono-infecção ou em bi-associação. F. nucleatum e E. faecalis foram inoculados no sistema de canais radiculares de camundongos Balb/c, tanto isoladas como em bi-associação. Os animais foram sacrificados em 10 e 20 dias após a infecção, e os tecidos periapicais foram coletados. As expressões do mRNA das citocinas RANKL, TNF-a, IFN-g, TGF-b e IL-10 foram analisadas por meio do real-time PCR. O teste de Kruskal-Wallis foi utilizado para análise estatística. A mono-infecção com F. nucleatum induziu alta expressão de RANKL e TNF-a, enquanto sua modulação ocorreu devido à IL-10. A alta expressão de IFN-g no dia 20 foi regulada positivamente por E. faecalis e RANKL; TNF-a foi regulada positivamente por um mecanismo independente via IL-10 e TGF-b. A bi-associação (F. nucleatum e E. faecalis) estimulou uma alta expressão de RANKL, TNF-a e IFN-g, que parece ser modulada por TGF-b após 20 dias. A expressão gênica de citocinas pró-inflamatórias foi mais proeminente nos estágios iniciais da infecção periapical experimental, com concomitante redução no período tardio. Este fenômeno pode ser regulado por IL-10 e TGF-b em uma condição de infecção específica.

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.

Effects of Copaifera duckei Dwyer oleoresin on the cell wall and cell division of Bacillus cereus.

The aim of this work was to evaluate the antibacterial activity of Copaifera duckei oleoresin and to determine its possible mechanism of action against bacteria of clinical and food interest. The antibacterial activity was determined by agar diffusion and dilution methods; the mechanism of action by transmission electron microscopy and by SDS-PAGE; the bioactive compounds by bioautography; and the chemical analysis by GC/MS. Oleoresin showed activity against nine of the 11 strains of bacteria tested. Bacillus cereus was the most sensitive, with a MIC corresponding to 0.03125 mg ml(-1) and with a bactericidal action. Oleoresin acted on the bacterial cell wall, removing proteins and the S-layer, and interfering with the cell-division process. This activity probably can be attributed to the action of terpenic compounds, among them the bisabolene compound. Gram-negative bacteria tested were not inhibited. C. duckei oleoresin is a potential antibacterial, suggesting that this oil could be used as a therapeutic alternative, mainly against B. cereus.

Proteomic changes in Bacteroides fragilis exposed to subinhibitory concentration of piperacillin/tazobactam.

Bacteroides fragilis is the anaerobe most frequently isolated from clinical specimens and piperacillin/tazobactam is among the drugs that can be used to treat polymicrobial infections in which this bacteria is often involved. During antibiotic therapy, inhibitory concentrations of antibiotics are always followed by subinhibitory concentrations which can generate phenotypic changes in bacteria. So, in this study we aimed to evaluate changes in the proteomic profile of B. fragilis grown in a sub-MIC of PTZ, using 2-D electrophoresis followed by matrix-assisted laser desorption/ionization time-of-flight/time of-flight. Analysis of the 2-DE gels showed 18 spots with significantly different volume percentages between experimental conditions and 12 were successfully identified by MS/MS. Two proteins with decreased abundance in sub-MIC condition were involved in the glycolysis (glyceraldehyde-3-phosphate dehydrogenase and triose phosphate isomerase), others two involved in amino acid metabolism (Oxoacyl-(acyl-carrier protein) synthase II and dihydrodipicolinate reductase), and finally, one protein involved in fatty acid metabolism (UDP-N-acetylglucosamine acyltransferase). Among the proteins with increased abundance, we founded three ATP synthase (alpha, beta, and alpha type V), which could be involved in antibiotic bacterial resistance by efflux pump, one protein involved in glycolysis (enolase), and one involved in protein degradation (aminoacyl-histidine dipeptidase). In conclusion, our data show overall changes in the proteome of B. fragilis conducted by sub-MIC of PTZ, whose consequences on bacterial physiology deserve further investigation.

Count, identification and antimicrobial susceptibility of bacteria recovered from dental solid waste in Brazil.

In Brazil, few studies on microbial content of dental solid waste and its antibiotic susceptibility are available. An effort has been made through this study to evaluate the hazardous status of dental solid waste, keeping in mind its possible role in cross-infection chain. Six samples of solid waste were collected at different times and seasons from three dental health services. The microbial content was evaluated in different culture media and atmospheric conditions, and the isolates were submitted to antibiotic susceptibility testing. A total of 766 bacterial strains were isolated and identified during the study period. Gram-positive cocci were the most frequent morphotype isolated (48.0%), followed by Gram-negative rods (46.2%), Gram-positive rods (5.0%), Gram-negative-cocci (0.4%), and Gram-positive coccobacillus (0.1%). Only two anaerobic bacteria were isolated (0.3%). The most frequently isolated species was Staphylococcus epidermidis (29.9%), followed by Stenotrophomonas maltophilia (8.2%), and Enterococcus faecalis (6.7%). High resistance rate to ampicillin was observed among Gram-negative rods (59.4%) and Gram-positive cocci (44.4%). For Gram-negative rods, high resistance was also noted to aztreonam (47.7%), cefotaxime (47.4%), ceftriaxone and cefazolin (43.7%), and ticarcillin-clavulanic acid (38.2%). Against Gram-positive cocci penicillin exhibit a higher resistance rate (45.0%), followed by ampicillin, erythromycin (27.2%), and tetracycline (22.0%). The present study demonstrated that several pathogenic bacteria are present in dental solid waste and can survive after 48 h from the waste generation time and harbor resistance profiles against several clinical recommended antibiotics.

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.

Partial characterization of antagonistic substance produced by a Clostridium butyricum strain

The production of antagonistic substance by bacterium present in the infected root canal system (RCS) probably is an important ecological factor for its successful colonization of the local. The objective of this study was to partially characterize an antagonistic substance produced by a Clostridium butyricum isolated from infected RCS.Production of inhibitory compound was evaluated by the agar double layer diffusion technique using Fusobacterium nucleatum and Bifidobacterium adolescentis as indicator bacteria. The physicochemical and biochemical factors tested for the partial characterization were influence of pH and temperature and susceptibility to the action of some proteolytic enzymes. An inhibition zone was observed against the two indicator strains and acidity and bacteriophage were rejected as responsible for this phenomenon. The inhibitory activity showed to be decreasing in a pH range from 3.5 to 6.5 and being stable at temperatures of 60°, 70° and 100°C, but completely inactivated when exposed at 121°C. The antagonistic activity was resistant to the proteolytic action of trypsin, a-chymotrypsin and papain. An antagonistic substance was produced by C. butyricum, which was thermo-resistant and probably of non-protein nature.

A produção de substâncias antagonistas por espécies bacterianas presentes em sistema de canais radiculares (SCR) infectados, tem um papel importante na colonização deste sítio. O objetivo deste estudo foi caracterizar parcialmente a substância antagonista produzida por amostra de Clostridium butyricum isolado de SCR infectados.A produção de substância antagonista foi avaliada pela técnica de difusão em ágar utilizando como bactérias indicadoras Fusobacterium nucleatum e Bifidobacterium adolescentis. Os parâmetros físico-químicos utilizados durante a caracterização parcial foram: pH, estabilidade térmica, susceptibilidade à ação das enzimas tripsina, a-quimiotripsina e papaína. Foi observada zona de inibição contra as duas amostras indicadoras e ainda foi demonstrado que ácidos e bacteriófagos não eram responsáveis por este fenômeno. A atividade inibitória mostrou-se diminuída em uma faixa de pH de 3.5 a 6.5 e estável em temperaturas de 60°, 70° e 100°C, sendo completamente inativada quando exposta a 121°C. A atividade antagonista foi resistente à ação das enzimas proteolíticas: tripsina, a-quimiotripsina e papaína. A substância antagonista produzida por C. butyricum é termoresistente e provavelmente de natureza não protéica.

In vitro activity of piperacillin/tazobactam and ertapenem against Bacteroides fragilis and Escherichia coli in pure and mixed cultures.

Ertapenem and piperacillin/tazobactam are beta-lactam antibiotics with a broad spectrum of activity used for the treatment of mixed infections in which Bacteroides fragilis and Escherichia coli play an important aetiological role. In this study, the activities of piperacillin/tazobactam and ertapenem (MIC and time-kill kinetics) against these bacteria were compared. MICs were determined by the agar dilution method, and the time and slope of time-kill curves were analysed. In the in vitro pharmacodynamic assays, pure and mixed cultures of E. coli and B. fragilis were exposed to peak concentrations of ertapenem (8.0 microg ml(-1)) and piperacillin/tazobactam (64.0/8.0 microg ml(-1)) for 48 h. Treatment with ertapenem reduced the viability of E. coli and/or B. fragilis by 3 logs in all experiments, whereas piperacillin/tazobactam only affected the viability of B. fragilis. Both drugs exhibited their fastest rates of killing when bacteria were grown in mixed cultures. According to the results, ertapenem exhibited activity similar to that of piperacillin/tazobactam against B. fragilis alone or in mixed culture. However, ertapenem exhibited a markedly higher activity against E. coli alone or in combination with B. fragilis relative to piperacillin/tazobactam.

Actinobacillus actinomycetemcomitans serotype-specific genotypes and periodontal status in Brazilian subjects.

Periodontitis is associated with members of the oral microbiota, such as Actinobacillus actinomycetemcomitans. To our knowledge, this is the first study to evaluate, by PCR, the occurrence of the six known bacterium serotypes that included subjects with and without periodontitis. Our group comprised 49 Brazilian subjects. We studied 146 bacterial isolates from 23 patients with aggressive or chronic periodontitis and 26 subgingival specimens from subjects with or without periodontitis, all originating in our collection. Serotypes b and c were observed in similar frequencies, and no subject harboured d, e, or f serotype strains. Around 78% subjects had single-serotype infection. Mixed infection was seen only in aggressive periodontitis patients. An association between serotype b and healthy periodontium and between serotype c and chronic periodontitis was observed. Our results diverge from those previously reported, which may be explained by specific distribution patterns in distinct populations. The association of different serotypes with the same periodontal status or conversely of a serotype with different periodontal conditions indicates that organism serotyping should not be used as a sole reliable marker for predicting the outcome of the infection. Evaluation of factors involved in human oral cavity colonization by subsets of A. actinomycetemcomitans is essential for elucidating organism-host-environment relationships.

New methods in the evaluation of chemical disinfectants used in health care services.

BACKGROUND: A considerable number of tests are recommended in the literature to evaluate in vitro commercial chemical solutions. The variety of tests reflects their limitations and the need to enhance disinfection process. METHODS: In this study the efficacy of 4 chemical disinfectants selected by their practical use in Health Care Services and by literature recommendation in aerobic and in strict anaerobic bacteria were evaluated by their practical use in Health Care Services and by literature recommendation in aerobic and in strict anaerobic bacteria. Viability was tested in biofilms grown on glass and rubber tip carriers. RESULTS: The results showed microbial growth in chemical solutions at concentrations recommended by the literature or at very close concentrations to them. Viable cells were recovered from biofilms after 30 minutes (Bacteroides fragilis) and 60 minutes (Streptococcus mutans and Salmonella tiphymurium) contact with 2.4% glutaraldehyde and after 60 minutes (S tiphymurium) in 2.0% glutaraldehyde. In 70% ethyl alcohol, S tiphymurium was viable up to 10 minutes, Escherichia coli up to 30 minutes, and S mutans up to 60 minutes. In 1% sodium hypochlorite, S mutans was viable up to 30 minutes and S tiphymurium up to 45 minutes. Detection of cell viability could be related to methodologic differences, including biofilm formation, as demonstrated by scanning electron microscopy. It should be emphasized that B fragilis, the most clinically relevant obligate anaerobe, remained viable in one routinely used solution. CONCLUSION: These findings pointed out the need of periodic surveillance of disinfectants' activity used in Health Care Services and the need of reviewing routines of disinfection protocols.