O16 Organoleptic assessment of pure odour compounds representative of the metabolic end‐products of oral microbes

We have measured various production rates of volatile compounds in tongue scrape cell suspensions, oral biofilm models and the oral cavity in situ and wish to relate these to equivalent levels of oral malodour as assessed by the human nose. Objectives To assess the relationship between measured concentrations of pure odourants and resultant organoleptic scores (using a defined 0–5 score). Methods Seven odour judges, all with experience of organoleptic assessment, were used in this study for all experiments carried out at a single site (UWE, Bristol). A wide range of pure odourants were prepared at a range of concentrations (from a stock of 0.1 M) and were dispensed as 12 ml volumes into ‘universal’ bottles (24 ml capacity) leaving a headspace of 12 ml. The bottles were secured with rubber‐lined metal caps, labelled with a randomized code and were presented to the odour judges for assessment using the Rosenberg 0–5 scale. The volatile sulphur compounds (H₂S and CH₃SH) were presented as gases with dilutions being prepared through a dynamic gas flow rig (using oxygen free nitrogen as the diluent) and presented to the odour judges at a flow rate of 200 ml min^?1. Group means of determinations for each odourant were plotted against log10 of the concentration. Linear regression analysis was used to measure the gradient, 95% CI, and the scatter of the points around the gradient (R² value). Results Organoleptic scores were proportional to the log10 concentration of odourant. Detection thresholds (expressed as mol dm^‐3) were skatole (7.2 × 10^?13) < methyl mercaptan (1.0 × 10^?11) < trimethylamine (1.8 × 10^?11) < butyrate (2.3 × 10^?10) < hydrogen sulphide (6.4 × 10^?10) < putrescine (9.1 × 10^?10) < dimethyldisulphide (5.9 × 10^?8). Hydrogen sulphide showed highest olfactory power whilst putrescine was the lowest. Conclusions The olfactory response is exponential in nature. For any single compound, its contribution to malodour depends on: odour (olfactory) power, threshold (of detection) and volatility in addition to the concentration. It is now possible to relate production rates of VC's in models to typical levels of oral malodour perceived by the human nose.     

The inability of Streptococcus mutans and Lactobacillus acidophilus to form a biofilm in vitro on dentine pretreated with ozone

Background: The use of ozone therapy in the treatment of dental caries is equivocal. The aim of this study was to use an in vitro model to determine the effects of prior ozone application to dentine on biofilm formation and to measure any associated reduction in bacteria viability. Methods: Twenty dentine discs were bonded to the bases of 5 mL polycarbonate screw top vials. Ten dentine discs were infused with ozone for 40 seconds, 10 samples remained untreated as a control. The vials were filled with nutrient medium, sterilized and placed into the outflow from a continuous chemostat culture of Streptococcus mutans and Lactobacillus acidophilus for four weeks. At the conclusion of the experiment bacterial growth was monitored by taking optical density readings of the growth medium in each vial and the outer surface of the dentine specimens were examined by scanning electron microscopy as shown by SEM analysis. Results: Ozone infusion prevented biofilm formation on all the treated samples while there was substantial biofilm present on the control specimens. While the average optical density of the control specimens was almost twice that of the ozone infused dentine (0.710 for the control with a SD of 0.288 and 0.446 for the ozonated samples with a SD of 0.371), the results were not significant (p > 0.05). Conclusions: This preliminary study has shown that the infusion of ozone into non‐carious dentine prevented biofilm formation in vitro from S. mutans and L. acidophilus over a four‐week period. The possibility exists that ozone treatment may alter the surface wettability of dentine through reaction with organic constituents.     

Use of influenza vaccines in children with an egg allergy

Children are at increased risk of morbidity from influenza. Influenza vaccines are grown in eggs, leading to a minute amount of egg protein in their composition. Recent research and new practice parameters spurred by the 2009 global influenza pandemic have challenged the need to withhold influenza vaccine from patients with an egg allergy. The available data suggest that anaphylaxis from influenza vaccines is exceptionally rare, even in patients with an egg allergy. Reported allergic reactions to trivalent inactivated influenza vaccine and pH1N1 influenza vaccines have been rare; when reactions occurred, they have not caused anaphylaxis. This position statement reviews the available evidence on influenza vaccine/egg allergy-related anaphylaxis, and recommends protocols to safely administer the trivalent inactivated influenza vaccine in lower- and higher-risk children with an egg allergy.     

Management of childhood asthma in Western Australia

Aims:   The study aimed to determine how childhood asthma is managed in Western Australia by general practitioners (GPs) and specialist paediatricians.
Methods:   A questionnaire survey was sent to 992 GPs and specialist paediatricians, asking about practice and preferences regarding maintenance management of childhood asthma and treatment of acute asthma. Questions about asthma in infants, pre-school and school-aged children were asked separately.
Results:   The overall response rate was 24.7%, with 188/878 (21.4%) of GPs and 44/62 (71.0%) of paediatricians returning the questionnaire. The decision to start maintenance therapy was generally based on symptom frequency and severity. The first choice for maintenance treatment in all age groups was inhaled corticosteroids (ICS). The second most common treatment varied according to age group, with short-acting β₂-agonist (SBA) preferred for infants, montelukast or short-acting β₂-agonist for pre-schoolers and combination therapy (ICS + long action β₂-agonist) for school-aged children. Objective monitoring of lung function with peak flow or spirometry, was used by 40% of GPs and 59% of paediatricians. Acute asthma was primarily managed with inhaled salbutamol and oral corticosteroids. There were few differences in treatment choice between GPs and paediatricians. Many GPs indicated that they did not treat asthma in infants without specialist consultation.
Conclusions:   These data show good compliance by the minority of GPs responding to the survey and by paediatricians practising in Western Australia with current Australian asthma management guidelines. Major differences in treatment preferences between the groups were not detected.     

Unpredictable Effects of Rifampin as an Adjunctive Agent in Elimination of Rifampin-Susceptible and -Resistant Staphylococcus aureus Strains Grown in Biofilms

The use of rifampin as an adjunct in biofilm-associated infections is based on the ability to penetrate into biofilms and a presumed activity against dormant bacteria. Yet, its efficacy remains contradictory, and rifampin-resistant strains frequently emerge during therapy. Therefore, the efficacy against rifampin-susceptible and isogenic rifampin-resistant methicillin-susceptible Staphylococcus aureus (MSSA) strains was evaluated. Biofilms were generated under static conditions using MSSA with various genetic backgrounds. Oxacillin alone or with rifampin at various concentrations was subsequently added, and after 24 h biomass and viable cell counts were determined. Upon rifampin addition, interstrain variations in viable count change, ranging from a tendency toward antagonism to synergy, were observed among all strains tested, irrespective of the genetic background of the strain. Similar variations were observed in changes in biomass. The decrease in viable count upon rifampin addition was negatively correlated to formation of large amounts of biomass, since strains embedded by more biomass showed a diminished reduction in viable count. Rifampin (1 μg/ml) as adjunct to oxacillin achieved greater reductions in biomass produced by most rifampin-susceptible isolates, ranging from 17 to 54%, compared to 4% for oxacillin alone. In contrast, rifampin had no additional value in reduction of biomass of isogenic rifampin-resistant mutants. At subinhibitory concentrations of rifampin (0.008 μg/ml), none of the strains tested yielded an extra reduction in biomass that was ≥40%. In conclusion, the effects of rifampin as adjunct on biomass and viable count were unpredictable, and the use of rifampin against biofilm containing rifampin-resistant strains seems unwarranted.Bacteria embedded in biofilm are often hard to eradicate, which will often result in failure of antibiotic therapy. A biofilm can appear and persist on implanted or indwelling devices. Adherence to bone or natural tissue can also occur. As a consequence of biofilm formation, foreign body infections are a risk factor for persistent bacteremia (12).Staphylococcus aureus biofilm-infected devices often require removal in combination with antimicrobial therapy (6). Even if an infection seems to be cured, a subset of bacteria can survive within the partly unremoved biofilm and the infection can remanifest after several years. These are the so-called low-grade infections (30). The ideal antibiotic should be able to diffuse properly into biofilms, eradicate dormant bacteria, and kill phagocytized S. aureus, since foreign body infections are associated with intracellular S. aureus (16, 18). Rifampin meets these criteria partially (28). Rifampin penetrates biofilms adequately (38) and improves the diffusion of a companion agent through the biofilm (8). It also reduces the adherence of bacteria to surfaces (28). Furthermore, rifampin addition eliminates intrinsic rifampin-resistant Pseudomonas aeruginosa (MIC, 32 μg/ml) from biofilms (11). Therefore, it could be hypothesized that the presence of rifampin leads to biofilm matrix disintegration. However, rifampin cannot be used alone due to the rapid emergence of resistance (37), and it is not as effective as presumed against slow-growing bacteria (21, 38). An alternative approach for S. aureus biofilm-associated infections is the addition of rifampin to a companion drug. In clinical practice, rifampin addition has been occasionally demonstrated as beneficial in terms of clinical or bacteriological cure rates (39), especially for prosthetic device-related infections (10, 18, 22). However, its effect remains poorly defined, since the number of supporting human studies is limited and most of them have been underpowered (10, 18, 22, 29). Moreover, recently performed in vitro studies have demonstrated antagonistic effects after addition of rifampin in experimental foreign body infection and endocarditis models (15, 17).Exposure to combination therapy including rifampin frequently results in the emergence of rifampin-resistant subpopulations, which might hinder clearance of the infection (25). This is probably due to the fact that the pharmacokinetics of the companion drug were different from that of rifampin. Preferably, the companion drug needs to penetrate easily through diverse layers of a biofilm to prevent the development of rifampin resistance. But, although some antibiotics penetrate adequately through biofilms, bacteria may be protected from killing by thickening of the cell wall (38). A high bacterial load is another cause of rapid resistance development (33). To overcome the emergence of resistance it is recommended that rifampin be initiated after the companion drug has been administered for 2 to 5 days, to reduce the high density of the initial burden (1), or at least until a substantial reduction in bacterial load has been achieved (4, 25).Since interstrain variability in response to rifampin addition might be responsible for the contradictory results obtained by various authors, the aim of the present study was to elucidate whether this variability does exist for strains between and within the S. aureus genetic backgrounds associated with multilocus sequence types (MLSTs) CC5, CC8, and CC30. Furthermore, since rifampin-resistant mutants emerge during therapy and rifampin is used for hypothesized destruction of the biofilm matrix, we evaluated whether continuation of exposure to rifampin is useful against biofilms containing rifampin-resistant methicillin-susceptible S. aureus (MSSA). In addition, we examined whether a potential effect was also present at a subinhibitory concentration.     

细粒棘球蚴重组抗原B的表达提取及其血清学检测初探

用基因工程技术制备出的细粒棘球绦虫重组抗原B（rAgB）表达载体,经诱导表达、亲和层析纯化获得具生物活性的重组蛋白质rAgB,用Western-Blot法检测病人血清。结果显示rAgB敏感性为91．6％（44／48）,特异性为93．8％（30／32）,其中10例泡球蚴（AE）病人及10例肿瘤病人血清均无交叉反应。说明rAgB具有较高的敏感性及特异性,可用于包虫病的常规血清学诊断,rAgB在宿主菌JM109内稳定表达,因此可在实验室内大量制备用于血清学诊断的rAgB。     

泡状棘球蚴病宿主淋巴细胞的变化及意义

目的　为探讨泡状棘球蚴病宿主体内淋巴细胞在免疫调节和发病中的作用。方法　对泡球蚴感染BALB/c小鼠观察至 2 5周 ,在不同时间取脾制备细胞悬液 ,检测CD+ 4 ,CD+ 8细胞数量。对 2 5例泡球蚴病患者和 18例健康人群 ,用FCM分析了CD+ 3 ,CD+ 4 ,CD+ 8,CD+ 19,CD+ 3 8,CD+ 56和HLA -DR+ 细胞的变化。结果　泡球蚴感染BALB/c小鼠后 ,1～ 8周以CD+ 4 细胞为主 ,随后CD+ 4 细胞减少 ,CD+ 8细胞增加 ,2 0周后改变显著 (P <0 0 5 ) ,CD+ 4 /CD+ 8比值迅速倒置。泡状棘球蚴病患者CD+ 3细胞未发生改变 ,CD+ 4 细胞较正常对照组下降 (P <0 0 5 ) ,CD+ 8细胞上升 (P <0 0 5 ) ,使CD+ 4 /CD+ 8比值降低 (P <0 0 5 )。CD+ 56细胞较正常对照组显著性降低 (P <0 0 1) ,CD+ 19,CD+ 3 8和HLA -DR+ 细胞未发生改变 (P >0 0 5 )。结论　泡球蚴感染小鼠前 8周 ,以CD+ 4 细胞反应为主 ,具有保护性免疫。感染后期逐渐以CD+ 8细胞为主 ,使机体呈免疫抑制状态 ,有利于泡球蚴生存。泡状棘球蚴病患者机体呈免疫抑制状态 ,有利于泡状棘球蚴在体内的生长