In Vitro Models of Bacterial Biofilms: Innovative Tools to Improve Understanding and Treatment of Infections.

Bacterial infections are a growing concern to the health care systems. Bacteria in the human body are often found embedded in a dense 3D structure, the biofilm, which makes their eradication even more challenging. Indeed, bacteria in biofilm are protected from external hazards and are more prone to develop antibiotic resistance. Moreover, biofilms are highly heterogeneous, with properties dependent on the bacteria species, the anatomic localization, and the nutrient/flow conditions. Therefore, antibiotic screening and testing would strongly benefit from reliable in vitro models of bacterial biofilms. This review article summarizes the main features of biofilms, with particular focus on parameters affecting biofilm composition and mechanical properties. Moreover, a thorough overview of the in vitro biofilm models recently developed is presented, focusing on both traditional and advanced approaches. Static, dynamic, and microcosm models are described, and their main features, advantages, and disadvantages are compared and discussed.

The effect of sophorolipids against microbial biofilms on medical-grade silicone.

Recent medical strategies rely on the search for effective antimicrobials as surface coatings to prevent and treat infections in humans and animals. Biosurfactants have recently been shown to have properties as antiadhesive and antibiofilm agents. Sophorolipids in particular are biosurfactant molecules known to act as therapeutic agents. This study aimed to evaluate antimicrobial properties of sophorolipids in medical-grade silicone discs using strains of clinical relevance. Sophorolipids were produced under fed batch conditions, ESI-MS analyses were carried out to confirm the congeners present in each formulation. Three different products were obtained SLA (acidic congeners), SL18 (lactonic congeners) and SLV (mixture of acidic and lactonic congeners) and were tested against Staphylococcus aureus ATCC 6538, Pseudomonas aeruginosa ATCC 10145 and Candida albicans IHEM 2894. All three congener mixtures showed a biofilms disruption effect (> 0.1 % w/v) of 70 %, 75 % and 80 % for S. aureus, P. aeruginosa and C. albicans, respectively. On pre-coated silicone discs, biofilm formation of S. aureus was reduced by 75 % using SLA 0.8 % w/v. After 1.5 h the inhibition of C. albicans attachment was between 45-56 % whilst after 24 h incubation the percentage of inhibition for the cell attachment increased to 68-70 % when using SLA 0.8 % w/v. Finally, in co-incubation experiments SLA 0.05 % w/v significantly reduced the ability of S. aureus and C. albicans to form biofilms and to adhere to surfaces by 90-95 % at concentrations between 0.025-0.1 % w/v. In conclusion sophorolipids significantly reduced the cell attachment of both tested strains which suggests that these molecules could have a potential role as coating agents on medical grade silicone devices for the preventions of Gram positive bacteria and yeast infections.

Inhibition of Candida albicans adhesion on medical-grade silicone by a Lactobacillus-derived biosurfactant.

AIMS: The study aimed at investigating the ability of biosurfactant (BS) produced by a Lactobacillus brevis isolate (CV8LAC) to inhibit adhesion and biofilm formation of Candida albicans on medical-grade silicone elastomeric disks (SEDs). METHODS AND RESULTS: Biosurfactant activity was evaluated at physiological conditions, by means of co-incubation and precoating assays. Additionally, BS extract was tested for antifungal susceptibility against C. albicans in both planktonic and sessile form. Biofilm covered surface and hyphae and blastospores occurrence were quantified by scanning electron microscopy (SEM) and image analysis. BS did not inhibit growth of C. albicans in both planktonic and sessile form. Nevertheless, co-incubation with 2000 µg ml(-1) BS significantly reduced biofilm formation on SEDs surface by 89, 90 and 90% after 24, 48 and 72 h of incubation. Fungal adhesion and biofilm formation to precoated SEDs was reduced by 62, 53, 50 and 44% after 1.5, 24, 48 and 72 h. SEM showed a significant reduction of biofilm covered surface in precoated disks but no differences in the production of hyphae or blastospores, except at 1.5 h of incubation. CONCLUSIONS: This study demonstrated that CV8LAC BS has the ability to counteract significantly the initial deposition of C. albicans to silicone surfaces and to effectively slow biofilm growth. SIGNIFICANCE AND IMPACT OF THE STUDY: The anti-adhesive properties of the CV8LAC BS suggest a potential role of the coating for preventing fungal infection associated to silicone medical devices.

Control integral de embarazo y salud materno neonatal en San Pedro de Guasayán antes y después de la implementación de la asignación por embarazo / Comprehensive birth control and maternal and neonatal health in San Pedro de Guasayán before and after implementation of the pregnancy allowance

INTRODUCCIÓN En San Pedro de Guasayán, Santiago del Estero, se observó que las mujeres no se realizaban los controles prenatales necesarios. Argentina cuenta con políticas públicas que buscan mejorar los índices de morbimortalidad materna infantil, entre ellas la Asignación por Embarazo para Protección Social (AEPS). OBJETIVOS Analizar el comportamiento de los indicadores de control integral del embarazo y de salud materna neonatal en las mujeres y sus hijos recién nacidos, asistidos en el Hospital de San Pedro de Guasayán antes (mayo 2009-abril 2011) y después (mayo 2011-abril 2013) de la implementación de la AEPS. MÉTODOS Se realizó un estudio de corte transversal en períodos consecutivos (mayo 2009-abril 2011 y mayo 2011-abril 2013). La población estuvo compuesta por embarazadas y sus hijos recién nacidos, elegibles para la AEPS, controladas y/o asistidas en el hospital entre mayo de 2009 y abril de 2013. Las principales variables fueron AEPS, controles del embarazo, consejería integral, ecografías, análisis de laboratorio, esquema de vacunación, morbimortalidad materna y morbimortalidad infantil. Para el análisis estadístico se usó el test exacto de Fisher; se consideró como diferencia significativa p≤0,05. RESULTADOS Se estudiaron en el período pre N=73 y en el post N=53. Existe evidencia para asegurar que hay diferencia significativa en el período post en las siguientes variables consejería integral (p=0,0277), infección urinaria/vaginal (p=0,0356), período intergenésico corto (p=0,0003), ningún control prenatal (p=0,0396), prematurez (p=0,042). DISCUSIÓN Hay diferencias significativas encontradas a favor del período posterior a la AEPS. La investigación muestra que hay que reforzar la capacitación del recurso humano en el adecuado control del embarazo, el diagnóstico precoz de factores de riesgo y la importancia de los registros como documentos éticos y legales.

Monitoring environmental Aspergillus spp. contamination and meteorological factors in a haematological unit.

The opportunistic pathogens belonging to the Aspergillus genus are present in almost all seasons of the year, and their concentration is related to meteorological conditions. The high density of Aspergillus spp. conidia in a haematological hospital ward may be a significant risk factor for developing invasive fungal diseases in immunocompromised patients. Aim of the present study was to evaluate the variability of airborne Aspergillus spp. conidia contamination in a Haematological Unit (HU) within a period of 16 months in relation with some meteorological parameters. An environmental Aspergillus surveillance was conducted in the HU in four rooms and their bathrooms, in the corridor and in three external sites using an agar impact sampler. During each sampling, temperature and relative humidity at each site were recorded and current wind speed and rainfall events were taken from the official weather service. Aspergillus spp. conidia concentration differed significantly across the sampling sites. Internal Aspergillus spp. loads were significantly dependent on temperature, internal relative humidity and rain. External conidia concentrations were significantly influenced by outdoor temperature and relative humidity. A suitable indicator was introduced to evaluate the seasonal distribution of Aspergillus spp. conidia in the sampling sites, and a significant dependence on this indicator was observed inside the HU. Seventeen different fungal species belonging to the Aspergillus genus were detected during the sampling period. Aspergillus fumigatus was the most frequently isolated species and its distribution depended significantly on the seasonal indicator both inside and outside the hospital ward.

The assessment of airborne bacterial contamination in three composting plants revealed site-related biological hazard and seasonal variations.

AIMS: The purpose of this study was to evaluate the degree of bacterial contamination generated by three Italian composting plants (1, 2 and 3) in two different seasons and to assess the health risk for the employees. METHODS AND RESULTS: Aerosols samples were collected with an agar impact sampler. Several plant sites and external upwind and downwind controls were examined. Total colony-forming counts of mesophilic and thermophilic bacteria, actinomycetes and streptomycetes, Gram-negatives, coliforms and sulfite-reducers were determined. Selective media were used in order to isolate pathogenic bacteria. The levels of total mesophilic and thermophilic micro-organisms ranged between 33 and >40,000 CFU m(-3) in plant 1, 39 and 18,700 CFU m(-3) in plant 2 and 261 and 6278 CFU m(-3) in plant 3. Strains of Escherichia coli, Staphylococcus aureus and Clostridium perfringens were also found. CONCLUSIONS: The plants monitored in this study have proved to be sources of aerosolized bacteria. The activities involving mechanical movement of the composting mass and the indoor activities were of greatest potential risk. In all the studied plants, a statistically significant dependence was found between the bacterial contamination and the season for some or almost all the analysed parameters, but a clear seasonal trend could not be observed. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides broad evidence of bacterial aerosol dispersion and site-related biological hazards that may be useful to the regional government to implement regulations on worker safety in composting plants.

Influence of biotic and abiotic factors on human pathogens in a finished compost.

The role of indigenous microflora of a finished compost, defined NK12, on the growth suppression of pathogens under different moisture and temperature storages was investigated. Total count of mesophilic and thermophilic bacteria was evaluated by the most probable number method and growth of seeded Salmonella arizonae 3924 serogroup B and enteropathogenic Escherichia coli 84 M in NK12 at different moisture temperature conditions was monitored. Results on sterile and non-sterile NK12 were compared. In all tested experimental conditions, the NK12 indigenous microflora was stable and biologically active. S. arizonae 3924 and E. coli 84 M grew rapidly in sterilized NK12 at different moistures and storage temperatures, and their growth was suppressed in non-sterilized NK12. Pathogens inactivation was lower when compost was stored at 40% and 80% humidity and at 37 degrees C. Our results show that the major role in the pathogens suppression was played by the indigenous microflora of the finished compost, although physical factors too influenced the growth phenomenon.

The effect of chronic unpredictable stress on locomotor and exploratory activity in male rats with different endogenous prolactin levels.

The probable role of prolactin (PRL) on the behavioral responses evoked by chronic unpredictable stress (CUS) was studied in adult male rats. Three experiments were performed examining the effect of CUS on behavioral performance in: (i) intact rats with normal endogenous PRL levels, (ii) rats with high endogenous PRL levels, and (iii) rats with low endogenous PRL levels. Behavioral parameters studied were: locomotion, head-dipping, rearing and grooming. Endocrine parameters studied were: PRL and corticosterone (C) plasma concentrations. In Experiment (i) results showed that CUS inhibited significantly locomotion, head-dipping and rearing activity. No variations in PRL plasma levels were found but a significant increase in C was detected. In Experiment (ii) the hyperprolactinaemia induced by pituitary transplants in the kidney capsule blocked partially the inhibition of locomotion due to CUS. No modifications on head-dipping, rearing and grooming were observed. PRL levels in these rats were consistently high as expected and CUS regimen did not change the hormone concentrations in blood. The C response due to CUS, however was completely blocked in the pituitary-implanted group. In Experiment (iii), repeated treatment with bromocriptine (5 mg/kg i.p.) significantly increased the inhibitory effect of CUS on locomotion, head-dipping and rearing. Grooming was also decreased in CUS-treated rats. PRL levels in these animals was low as expected and the C response due to CUS was significantly increased. Results give support to the concept that PRL may have a regulatory role in CUS.

Neonatal chronic stress induces subsensitivity to chronic stress in adult rats. I. Effects on forced swim behavior and endocrine responses.

An influence of early stimulation on sensitivity to acute stress in adulthood has been reported. The purpose of the present work was to determine the effect of exposure of male and female rats to three models of chronic stress (unpredictable stress, cold stress and handling) from day 2 to day 15 of life on behavioral and endocrine sensitivity to chronic stresses in adulthood. The chronic stresses applied in adulthood were a model of intermittent cold stress (daily 30-min sessions at -20 degrees C for 15 days) and the Katz's model of unpredictable chronic stress (15 days). Forced swim behavior and serum concentration of the stress-sensitive hormones, corticosterone and prolactin, were chosen to investigate stress sensitivity. It was found that all neonatal treatments stimulated body weight gain, did not cause infant mortality and did not affect forced swim behavior as adult. The repetitive exposure to cold stress in adulthood did not cause major impairment of forced swim behavior and did not affect basal levels of serum corticosterone and prolactin in either control or experimental rats. These findings support the view that repeated stressors can induce behavioral and endocrine adaptation in rats. The neonatal treatments did not affect this characteristic. The exposure of control rats to the unpredictable stress model severely impaired forced swim behavior and increased basal levels of serum corticosterone and prolactin. This observation conforms to the view that standard laboratory rats cannot adapt to unpredictable chronic stress. This has been reported to cause a behavioral depression syndrome comprising forced swim deficit and endocrine alterations.(ABSTRACT TRUNCATED AT 250 WORDS)

A further analysis of behavioral and endocrine effects of unpredictable chronic stress.

Tolerance can develop when rats are repeatedly exposed to some predictable stressors. This does not occur, however, when rats are exposed to unpredictable chronic stress. In this study we have analyzed some behavioral and endocrine effects in male and female rats treated daily with unpredictable emotional stressor (ES-groups) or unpredictable physical stressors (PS-groups) over a 14-day period. Animals were then submitted to three behavioral tests at 24 hr intervals. Experiment 1 shows that when rats were tested in an enriched environment both total motor activity and exploration of the novel object were impaired by the PS treatment. This suggests the occurrence of motivational deficit. The fact that the PS-groups also showed increased intratest defecation suggests increased emotionality. When animals were submitted to an emergence test the PS-groups showed longer emergence latency, lower frequency of emergencies and lower time spent exploring the emergence compartment than the ES- and the C-group. This strongly supports that the PS treatment increased emotionality in rats. When ES- and PS-groups were exposed to a forced swim test they showed longer immobility duration (despair reaction) but only the PS-group displayed lower frequency of jumps (escape reaction). Results of all tests performed revealed that females were more resistant than males to the behavioral effects of the PS treatment. The day after the behavioral testing was completed, basal levels of corticosterone and prolactin were investigated in male subjects. The PS-group showed higher baseline levels of these "stress labile" hormones than the ES and the C-group.(ABSTRACT TRUNCATED AT 250 WORDS)