Production of biofilm by Staphylococcus aureus: Association with infective endocarditis?

OBJECTIVES

Staphylococcus aureus is a well-known biofilm-producing pathogen that is capable of causing chronic infections owing to its ability to resist antibiotic treatment and obstruct the immune response. However, the possible association between high biofilm production and infective endocarditis (IE) has not been assessed. Our objective was to compare production of biofilm by S. aureus strains isolated from patients with bacteremia and IE, catheter-related bloodstream infection (C-RBSI), or non-device associated bacteremia.

METHODS

We isolated 260 S. aureus strains from the blood of patients with bacteremia who were diagnosed during hospital admission between 2012 and 2015. Patients were divided into 3 groups according to whether they had IE, C-RBSI, or non-device associated bacteremia. Biofilm production was measured in terms of biomass and metabolic activity using the crystal violet and XTT assays, respectively. High biomass and metabolic activity rates (based on tertile ranks classification) were compared between the 3 groups.

RESULTS

The high biomass and metabolic activity rates of each group were 41.9% and 37.2% for IE, 32.5% and 35.0%, for C-RBSI, and 29.0% and 33.3% for non-device associated bacteremia (p=0.325 and p=0.885, respectively).

CONCLUSIONS

High biomass and metabolic activity levels for S. aureus isolates from IE were similar to those of S. aureus isolates from C-RBSI or non-device associated bacteremia.

Production of biofilm by Staphylococcus aureus: Association with infective endocarditis?

OBJECTIVES

Staphylococcus aureus is a well-known biofilm-producing pathogen that is capable of causing chronic infections owing to its ability to resist antibiotic treatment and obstruct the immune response. However, the possible association between high biofilm production and infective endocarditis (IE) has not been assessed. Our objective was to compare production of biofilm by S. aureus strains isolated from patients with bacteremia and IE, catheter-related bloodstream infection (C-RBSI), or non-device associated bacteremia.

METHODS

We isolated 260 S. aureus strains from the blood of patients with bacteremia who were diagnosed during hospital admission between 2012 and 2015. Patients were divided into 3 groups according to whether they had IE, C-RBSI, or non-device associated bacteremia. Biofilm production was measured in terms of biomass and metabolic activity using the crystal violet and XTT assays, respectively. High biomass and metabolic activity rates (based on tertile ranks classification) were compared between the 3 groups.

RESULTS

The high biomass and metabolic activity rates of each group were 41.9% and 37.2% for IE, 32.5% and 35.0%, for C-RBSI, and 29.0% and 33.3% for non-device associated bacteremia (p=0.325 and p=0.885, respectively).

CONCLUSIONS

High biomass and metabolic activity levels for S. aureus isolates from IE were similar to those of S. aureus isolates from C-RBSI or non-device associated bacteremia.

[Development of a liquid fermentation system and encystment for a nitrogen-fixing bacterium strain having biofertilizer potential]

The indiscriminate use of chemical fertilizers has contributed to the deterioration of the biological, physical and chemical properties of the soil, resulting in the loss of its productive capacity. For this reason, the use of biofertilizers has emerged as a technological alternative. The objective of this research was to develop a suitable liquid fermentation system and encystment for the multiplication of Azotobacter chroococcum AC1 strain, a bacterium employed in a biofertilizer formulation produced at present by CARPOICA, Colombia. Sequential statistical designs were used to determine the conditions in the fermentation system. The interaction between agitation, aeration and pH was evaluated on the viable biomass (CFU/ml) of AC1. In addition, the encystment ability of the strain was evaluated using two encystment agents and the potential plant growth-promoting rhizobacteria (PGPR) activity was assessed by different techniques, such as nitrogen fixation by ARA, phosphate solubilization by the phospho-molybdenum-blue reaction and indolic compound production by colorimetric reaction using the Salkowski reagent. Results showed significant effects (p<0.05) on the viable biomass in the three conditions (pH, aeration and agitation) tested individually, in one dual interaction and one tripartite interaction, were demonstrated to have a positive effect on the response variable aeration and agitation. The addition of the two encystment agents evaluated, AE01 and AE02, demonstrated the ability of AC1 to form cysts under stress conditions. Likewise, fermentation and encystment conditions did not affect the biological activities tested.

Is Chronic Obstructive Pulmonary Disease Caused by Wood Smoke a Different Phenotype or a Different Entity?

Around 40% of the world's population continue using solid fuel, including wood, for cooking or heating their homes. Chronic exposure to wood smoke is a risk factor for developing chronic obstructive pulmonary disease (COPD). In some regions of the world, this can be a more important cause of COPD than exposure to tobacco smoke from cigarettes. Significant differences between COPD associated with wood smoke (W-COPD) and that caused by smoking (S-COPD) have led some authors to suggest that W-COPD should be considered a new COPD phenotype. We present a review of the differences between W-COPD and S-COPD. On the premise that wood smoke and tobacco smoke are not the same and the physiopathological mechanisms they induce may differ, we have analyzed whether W-COPD can be considered as another COPD phenotype or a distinct nosological entity.

Occupational and Biomass Exposure in Chronic Obstructive Pulmonary Disease: Results of a Cross-Sectional Analysis of the On-Sint Study

BACKGROUND

Although tobacco smoke is the main risk factor for chronic obstructive pulmonary disease (COPD), other inhaled toxics have also been associated with the disease. The present study analyzes data from exposure to these substances in a cohort of patients with COPD and assesses their impact on the clinical presentation of the disease.

METHODS

This is a cross-sectional analysis of the Clinical presentation, diagnosis and course of chronic obstructive pulmonary disease (On-Sint) study. All patients were smokers or ex-smokers as per protocol. In addition, during the inclusion visit patients were enquired about their occupational and biomass exposure history. The clinical features of patients with and without an added risk factor to tobacco were compared and those significant were entered in a multivariate logistic regression analysis, expressed as odds ratio (OR).

RESULTS

The sample size was 1214 patients with COPD, of which 1012 (83.4%) had tobacco as the only risk factor and 202 (16.6%) had additional ones, mainly 174 (14.3%) with occupational gases and 32 (2.6%) with biomass exposure. The geographical distribution of this exposure showed a preference for the northern parts of the country and the East coast. The biomass exposure was rather low. Male gender (OR: 2.180), CAT score (OR: 1.036) and the use of long-term oxygen therapy (OR: 1.642) were associated with having an additional risk factor in the multivariate analysis.

CONCLUSIONS

Occupational exposures are more common than biomass in Spain. COPD caused by tobacco plus other inhalants has some differential features and a more impaired quality of life.

Distribution of clinical phenotypes in patients with chronic obstructive pulmonary disease caused by biomass and tobacco smoke

INTRODUCTION

Exposure to biomass smoke is a risk factor for chronic obstructive pulmonary disease (COPD). It is unknown whether COPD caused by biomass smoke has different characteristics to COPD caused by tobacco smoke.

OBJECTIVE

To determine clinical differences between these two types of the disease.

METHODS

Retrospective observational study of 499 patients with a diagnosis of COPD due to biomass or tobacco smoke. The clinical variables of both groups were compared.

RESULTS

There were 122 subjects (24.4%) in the biomass smoke group and 377 (75.5%) in the tobacco smoke group. In the tobacco group, the percentage of males was higher (91.2% vs 41.8%, P<.0001) and the age was lower (70.6 vs 76.2 years, P<.0001). Body mass index and FEV1% values were higher in the biomass group (29.4±5.7 vs 28.0±5.1, P=.01, and 55.6±15.6 vs 47.1±17.1, P<.0001, respectively). The mixed COPD-asthma phenotype was more common in the biomass group (21.3% vs 5%, P<.0001), although this difference disappeared when corrected for gender. The emphysema phenotype was more common in the tobacco group (45.9% vs 31.9%, P=.009). The prevalence of the chronic bronchitis and exacerbator phenotypes, the comorbidity burden and the rate of hospital admissions were the same in both groups.

CONCLUSION

Differences were observed between COPD caused by biomass and COPD caused by tobacco smoke, although these may be attributed in part to uneven gender distribution between the groups.

Effectiveness of community forestry in Prey Long forest, Cambodia

Cambodia has 57% forest cover, the second highest in the Greater Mekong region, and a high deforestation rate (1.2%/year, 2005-2010). Community forestry (CF) has been proposed as a way to reduce deforestation and support livelihoods through local management of forests. CF is expanding rapidly in Cambodia. The National Forests Program aims to designate one million hectares of forest to CF by 2030. However, the effectiveness of CF in conservation is not clear due to a global lack of controlled comparisons, multiple meanings of CF, and the context-specific nature of CF implementation. We assessed the effectiveness of CF by comparing 9 CF sites with paired controls in state production forest in the area of Prey Long forest, Cambodia. We assessed forest condition in 18-20 randomly placed variable-radius plots and fixed-area regeneration plots. We surveyed 10% of households in each of the 9 CF villages to determine the proportion that used forest products, as a measure of household dependence on the forest. CF sites had fewer signs of anthropogenic damage (cut stems, stumps, and burned trees), higher aboveground biomass, more regenerating stems, and reduced canopy openness than control areas. Abundance of economically valuable species, however, was higher in control sites. We used survey results and geographic parameters to model factors affecting CF outcomes. Interaction between management type, CF or control, and forest dependence indicated that CF was more effective in cases where the community relied on forest products for subsistence use and income.