Evaluation of disinfection of surfaces at an outpatient unit before and after an intervention program.

BACKGROUND: Cleaning and disinfection processes must be improved so that there is a reduction in environmental contamination of frequent-contact surfaces. The objective of this study was to evaluate cleaning and disinfection of surfaces at a specialized healthcare unit after an intervention program. METHODS: Exploratory, longitudinal, and correlational study carried out in a medium-complexity clinic. Two hundred and forty samples from five surfaces were collected during three phases: diagnosis; implementation of an intervention program; and evaluation of immediate and long-term effects. In total, 720 evaluations were made, performed through three monitoring methods: visual inspection; adenosine triphosphate bioluminescence assay (ATP); and aerobic colony count (ACC). The Wilcoxon, Mann-Whitney, and Fisher's Exact tests were run to analyze data statistically. RESULTS: Cleaning and disinfection of surfaces were not being performed properly in most cases. Failure rates of surfaces reached 37.5 and 100% when the ATP and ACC procedures were used, respectively. However, after an intervention program, an improvement occurred. Success rates increased by 43.96% (ATP) and 12.46% (ACC) in phase I, by 70.6% (ATP) and 82.3% (ACC) immediately after interventions, and by 76.52% (ATP) and 85.76% (ACC) two months after the changes, showing that the program was effective. CONCLUSION: The present study reveals that implementing intervention actions with a cleaning and healthcare team brings benefits to prevent the spread of pathogenic agents through frequently touched hospital surfaces.

Isolation of culturable aerobic bacteria and evidence of Kerstersia gyiorum from the blowhole of captive Yangtze finless porpoises.

Bacterial respiratory illnesses are problematic in aquatic mammals such as the Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis; YFP), which is now at a critically endangered status. Yet little is known about the bacteria inhabiting the respiratory tract of YFPs. In this study, we preliminarily characterized the culturable aerobic bacteria from blow samples of captive YFPs. The bacterial diversity was assessed through cultivation by direct exhalation onto Columbia blood agar plates and identification of representative isolates through 16S rRNA gene sequence analysis. In total, eleven bacterial species belonging to four phyla Proteobacteria (71 %), Firmicutes (25 %), Bacteroidetes (3 %) and Actinobacteria (1 %) were identified. Most of these isolates were opportunistic pathogens found in respiratory illnesses in humans and animals. We also reported the first case of Kerstersia gyiorum isolated from an animal. This work provides a preliminary assessment of the bacteria present in the respiratory tract of captive YFPs, which will be an important first step in elucidating the roles of normal microbiota in maintaining respiratory health of YFPs. This study also points out the necessity of future long-term monitoring of blowhole microorganisms in the YFPs and making emergency preparedness plans for respiratory tract infections. These measures can aid in assessing the pathogenic risk of the critically endangered YFP populations.

Use of aerobic spores as a surrogate for cryptosporidium oocysts in drinking water supplies.

Waterborne illnesses are a growing concern among health and regulatory agencies worldwide. The United States Environmental Protection Agency has established several rules to combat the contamination of water supplies by cryptosporidium oocysts, however, the detection and study of cryptosporidium oocysts is hampered by methodological and financial constraints. As a result, numerous surrogates for cryptosporidium oocysts have been proposed by the scientific community and efforts are underway to evaluate many of the proposed surrogates. The purpose of this review is to evaluate the suitability of aerobic bacterial spores to serve as a surrogate for cryptosporidium oocysts in identifying contaminated drinking waters. To accomplish this we present a comparison of the biology and life cycles of aerobic spores and oocysts and compare their physical properties. An analysis of their surface properties is presented along with a review of the literature in regards to the transport, survival, and prevalence of aerobic spores and oocysts in the saturated subsurface environment. Aerobic spores and oocysts share many commonalities with regard to biology and survivability, and the environmental prevalence and ease of detection make aerobic spores a promising surrogate for cryptosporidium oocysts in surface and groundwater. However, the long-term transport and release of aerobic spores still needs to be further studied, and compared with available oocyst information. In addition, the surface properties and environmental interactions of spores are known to be highly dependent on the spore taxa and purification procedures, and additional research is needed to address these issues in the context of transport.

Saline storage of aerobic granules and subsequent reactivation.

Loss of structural stability and bioactivity during long-term storage and operation is primary challenge to field applications of aerobic granular processes. This study for the first time stored aerobic granules in 5%w/w NaCl solution at 4°C for 187d. The stored granules were then successfully reactivated and used for 85d in sequencing batch reactors (SBR) and continuous-flow reactors (CFR) at varying levels of chemical oxygen demand (COD). High-throughput sequencing results reveal that Thauera sp., Paracoccus sp., and Nitrosomonas sp. were the predominant in the stored aerobic granules, and Pseudoxanthomonas sp. accumulated during the reactivation process. Saline storage, in which cells are in an unculturable state by saline stress, is a promising storage process for aerobic granules.

Leucine incorporation by aerobic anoxygenic phototrophic bacteria in the Delaware estuary.

Aerobic anoxygenic phototrophic (AAP) bacteria are well known to be abundant in estuaries, coastal regions and in the open ocean, but little is known about their activity in any aquatic ecosystem. To explore the activity of AAP bacteria in the Delaware estuary and coastal waters, single-cell (3)H-leucine incorporation by these bacteria was examined with a new approach that combines infrared epifluorescence microscopy and microautoradiography. The approach was used on samples from the Delaware coast from August through December and on transects through the Delaware estuary in August and November 2011. The percent of active AAP bacteria was up to twofold higher than the percentage of active cells in the rest of the bacterial community in the estuary. Likewise, the silver grain area around active AAP bacteria in microautoradiography preparations was larger than the area around cells in the rest of the bacterial community, indicating higher rates of leucine consumption by AAP bacteria. The cell size of AAP bacteria was 50% bigger than the size of other bacteria, about the same difference on average as measured for activity. The abundance of AAP bacteria was negatively correlated and their activity positively correlated with light availability in the water column, although light did not affect (3)H-leucine incorporation in light-dark experiments. Our results suggest that AAP bacteria are bigger and more active than other bacteria, and likely contribute more to organic carbon fluxes than indicated by their abundance.

Size-dependent antibacterial activities of silver nanoparticles against oral anaerobic pathogenic bacteria.

Dental caries and periodontal disease are widespread diseases for which microorganism infections have been identified as the main etiology. Silver nanoparticles (Ag Nps) were considered as potential control oral bacteria infection agent due to its excellent antimicrobial activity and non acute toxic effects on human cells. In this work, stable Ag Nps with different sizes (~5, 15 and 55 nm mean values) were synthesized by using a simple reduction method or hydrothermal method. The Nps were characterized by powder X-ray diffraction, transmission electron microscopy and UV-vis absorption spectroscopy. The antibacterial activities were evaluated by colony counting assay and growth inhibition curve method, and corresponding minimum inhibitory concentration (MIC) against five anaerobic oral pathogenic bacteria and aerobic bacteria E. coli were determined. The results showed that Ag Nps had apparent antibacterial effects against the anaerobic oral pathogenic bacteria and aerobic bacteria. The MIC values of 5-nm Ag against anaerobic oral pathogenic bacteria A. actinomycetemcomitans, F. nuceatum, S. mitis, S. mutans and S. sanguis were 25, 25, 25, 50 and 50 µg/mL, respectively. The aerobic bacteria were more susceptible to Ag NPs than the anaerobic oral pathogenic bacteria. In the mean time, Ag NPs displayed an obvious size-dependent antibacterial activity against the anaerobic bacteria. The 5-nm Ag presents the highest antibacterial activity. The results of this work indicated a potential application of Ag Nps in the inhibition of oral microorganism infections.

Management of aerobic vaginitis.

Aerobic vaginitis is a new nonclassifiable pathology that is neither specific vaginitis nor bacterial vaginosis. The diversity of this microbiological peculiarity could also explain several therapeutic failures when patients were treated for infections identified as bacterial vaginosis. The diagnosis 'aerobic vaginitis' is essentially based on microscopic examinations using a phase-contrast microscope (at ×400 magnification). The therapeutic choice for 'aerobic vaginitis' should take into consideration an antibiotic characterized by an intrinsic activity against the majority of bacteria of fecal origin, bactericidal effect and poor/absent interference with the vaginal microbiota. Regarding the therapy for aerobic vaginitis when antimicrobial agents are prescribed, not only the antimicrobial spectrum but also the presumed ecological disturbance on the anaerobic and aerobic vaginal and rectal microbiota should be taken into a consideration. Because of their very low impact on the vaginal microbiota, kanamycin or quinolones are to be considered a good choice for therapy.

Culturing aerobic and anaerobic bacteria and mammalian cells with a microfluidic differential oxygenator.

In this manuscript, we report on the culture of anaerobic and aerobic species within a disposable multilayer polydimethylsiloxane (PDMS) microfluidic device with an integrated differential oxygenator. A gas-filled microchannel network functioning as an oxygen-nitrogen mixer generates differential oxygen concentration. By controlling the relative flow rate of the oxygen and nitrogen input gases, the dissolved oxygen (DO) concentration in proximal microchannels filled with culture media are precisely regulated by molecular diffusion. Sensors consisting of an oxygen-sensitive dye embedded in the fluid channels permit dynamic fluorescence-based monitoring of the DO concentration using low-cost light-emitting diodes. To demonstrate the general utility of the platform for both aerobic and anaerobic culture, three bacteria with differential oxygen requirements (E. coli, A. viscosus, and F. nucleatum), as well as a model mammalian cell line (murine embryonic fibroblast cells (3T3)), were cultured. Growth characteristics of the selected species were analyzed as a function of eight discrete DO concentrations, ranging from 0 ppm (anaerobic) to 42 ppm (fully saturated).

[Simultaneous nitrification and denitrification of membrane-aerated biofilm reactor].

A carbon membrane-aerated biofilm reactor was developed to treat municipal wastewater, in which the carbon and nitrogen were removed simultaneously. The results showed that COD removal, NH4+-N removal and TN removal efficiency could reach 82.5%, 95.1% and 84.2%, respectively, under the conditions of intra-membrane pressure of 13.6 kPa, HRT of 14 h, influent COD and NH4+-N concentrations of 338 mg/L and 75 mg/L. However, in the last period during the operation of the reactor, the TN removal efficiency dramatically decreased because of the excessive growth of biomass on the nonwoven fiber, which also had serious negative effect on nitrification course. The microbiological community and spatial profiles were observed by fluorescence in situ hybridization and scanning electron microscopy. The anaerobic and anoxic bacteria were mainly located in the outer anaerobic region of the biofilm, while the aerobic ammonium oxidizing bacteria were mainly located in the inner aerobic region of the biofilm. The co-existing and coupling effect of aerobic nitrifying bacteria and anaerobic denitrifying bacteria provided the large biological potential for the simultaneous nitrification and denitrification in the carbon membrane-aerated biofilm reactor.

Enhanced aerobic sludge granulation in sequencing batch reactor by Mg2+ augmentation.

Two sequencing batch reactors (SBRs) were concurrently operated to investigate the effect of Mg(2+) augmentation on aerobic granulation. Augmentation with 10mg/l Mg(2+) in R2 significantly decreased the sludge granulation (defined as that over 15% of granules were larger than 0.6mm) time from 32 days to 18 days, at the same time, the mean diameter of the granules in R2 was 2.9 mm after the granulation, which was consistently larger than that (1.8mm) in R1. Mg(2+)-fed granules were denser and more compact, showed better settling and had higher polysaccharide contents, but it did not result in a difference in microbial morphology. The results demonstrated that Mg(2+) enhanced the sludge granulation process in the sequencing batch reactor.

Optimising operation of a biological wastewater treatment application.

The objective of this work was to optimize (minimize) the compressed air required to control the rate of ammonia removal in a commercially operated wastewater bioreactor, while still maintaining operation within environmental consent limits. In order to do this, a nonlinear dynamic model based on the International Association on Water Quality (IAWQ) activated sludge model No. 3 was developed, expressing the nitrification kinetics and hydraulic dynamics of the system. From this model a steady state representation of the plant was derived, and simulated for various load characteristics experienced at the facility, and as a result an optimal load profile was developed for the compressed air distribution to the four aerobic zones. The optimal load profile will ensure that the amount of compressed air required to control the rate of ammonia removal is optimized.

Influence of free air space on microbial kinetics in passively aerated compost.

The influence of free air space (FAS) on passively aerated composting has been reported, but the quantitative relationship between FAS and the microbial kinetics in passively aerated compost has not been investigated. This relationship was studied by composting dairy manure and straw in an enclosed, passively aerated, cylindrical vessel. Based on this experimental system, conceptual and numerical models were developed in which the compost bed was considered to consist of layered elements, each being physically and chemically homogeneous. The microbial activity in each layer was represented in order to predict oxygen and substrate consumption and the release of water and heat. Convective transport of air, moisture, and heat through the layers was represented. Microbial growth and substrate consumption rates were described using modified first-order kinetics for each of the mesophilic and thermophilic temperature regimes. The values of the microbial kinetic parameters were adjusted for each layer based on an innovative, non-linear, statistical analysis of temperature histories recorded at different layers in the compost bed during three treatments (i.e., FAS values of 0.45, 0.52, and 0.65). Microbial kinetic rate constants were found to follow a sigmoid relationship with FAS, with correlation coefficients (R(2)) of 0.97 for the mesophilic stage and 0.96 for the thermophilic stage. Temperature histories and airflow measurements from a fourth treatment (FAS value of 0.57) were used as an independent check of the model's performance. Simulation results indicate that the model could predict the general trend of temperature development. A plot of the residuals shows that the model is biased, however, possibly because many parameters in the model were not measured directly but instead were estimated from literature. The result from this study demonstrates a new method for describing the relationship between microbial kinetics (k(max)) and substrate FAS, which could be used to improve the design, optimization, and management of passively aerated composting facilities.

[Growth model of aerobic granule under different salinities].

The stability of aerobic granules that developed under salinities of 1%, 2.5% and 5%, respectively, was evaluated using microscopic observations and size distribution. It was found that the size of granules increased and the diversity of size distribution became wider during the granulation period, and the size of mature granules distributed mainly in the range of 0.3-0.5 mm. Granules under the salinity of 1% showed high porosity and narrow size distribution and extracellular polymeric substances (EPS) linked the particles in the granules. In contrast, those under the salinity of 5% showed low porosity and wide size distribution and entanglement of filaments formed the frame work of granules. Disintegration of aerobic granules was found under the salinity of 2.5%, and the size distribution was found became wider, which may due to the unbalance growth between floc-forming and filamentous microorganisms. Therefore, it is reasonable to conclude that size distribution could effectively describe the stability of aerobic granules, namely, narrow size distribution indicates stability of aerobic granules. Furthermore, granules under low salinity were predominated by the floc-forming bacteria and thus EPS-linking was the main mechanisms of granulation, on the other hand, those under high salinity were predominated by filamentous microorganisms and thus the entanglements of filaments was the main mechanisms of granulation. Two models have been proposed for the growth of aerobic granules. One is heterogeneous growth of which the granule size distributes in a narrow spectrum and the granules growing with this model are stable because the conditions of growth and substrate utility are similar for all granules. Another is homogenous growth of which the granule size distributes in a wide spectrum and granules with this model are unstable.

Performance of a commercial inoculum for the aerobic biodegradation of a high fat content dairy wastewater.

The effectiveness of a commercial inoculum for degrading a dairy wastewater with high fat content was evaluated, and compared with an activated sludge inoculum from a dairy wastewater treatment pond. Both inocula reached similar chemical oxygen demand removal in batch experiments. The population dynamics was also studied by determining heterotrophic counts. Predominant microorganisms were differentiated by colony morphology and genomic fingerprinting (BOX-PCR) analysis. The higher population diversity and the wider range of CO2 production rate observed in batch reactors inoculated with activated-sludge, indicated that microorganisms from this inoculum were well adapted and may have had synergic activity for the degradation of the dairy effluent. When the bioreactor was operated with the commercial inoculum in continuous mode, according to its microbial growth kinetics, other microorganisms became predominant. These results showed that inoculated microorganisms did not persist in the open system and periodic addition of microorganisms may be needed to achieve a high performance treatment.

[Biological wastewater treatment and simultaneous generating electricity from organic wastewater by microbial fuel cell].

An air-cathode microbial fuel cell (ACMFC) was successfully started up using anaerobic activated sludge as inoculums, generating a voltage of 0.24V after inoculations for 110 h. When using acetate and glucose as substrate, voltage of 0.38V and 0.41V (based on external resistance of 1000 omega) is obtained; meanwhile, the maximum power density reaches 146.56 mW/m2 and 192.04 mW/m2 respectively, suggesting that organic wastewater can be used to produce electricity. Removal efficiency of 99% (acetate) and 87% (glucose) is achieved simultaneously, demonstrating that ACMFC can treat organic wastewater. Electron recovery efficiency as low as 10% for both acetate and glucose is observed mainly due to aerobic respiration of microorganisms caused by diffusion of oxygen molecular from the cathode, leading to electron loss. MFCs are capable of converting chemical energy presented in organic wastewater into electricity energy with accomplishments of wastewater treatments simultaneously, which possibly captures considerable benefits in terms of environments and economics.

Causes and control of filamentous growth in aerobic granular sludge sequencing batch reactors.

Poor long-term stability of aerobic granules developed in sequencing batch reactors (SBRs) remains a limitation to widespread use of aerobic granulation in treating wastewater. Filamentous growth has been commonly reported in aerobic granular sludge SBR. This review attempts to address the instability problem of aerobic granular sludge SBR from the perspective of filamentous growth in the system. The possible causes of filamentous growth are identified, including long retention times of solids, low substrate concentration in the liquid phase, high substrate gradient within the granule, dissolved oxygen deficiency in the granule, nutrient deficiency inside granule, temperature shift and flow patterns. Because of cyclic operation of aerobic granular sludge SBR and peculiarities of aerobic granules, various stresses can be present simultaneously and can result in progressive development of filamentous growth in aerobic granular sludge SBR. Overgrowth of filamentous bacteria under stress conditions appears to be a major cause of instability of aerobic granular sludge SBR. Specific recommendations are made for controlling filamentous growth.

Formation of aerobic granules and conversion processes in an aerobic granular sludge reactor at moderate and low temperatures.

Temperature changes can influence biological processes considerably. To investigate the effect of temperature changes on the conversion processes and the stability of aerobic granular sludge, an aerobic granular sludge sequencing batch reactor (GSBR) was exposed to short-term and long-term temperature changes. Start-up at 8 degrees C resulted in irregular granules that aggregated as soon as aeration was stopped, which caused severe biomass washout and instable operation. The presence of COD during the aerobic phase is considered to be the major reason for this granule instability. Start-up at 20 degrees C and lowering the temperature to 15 degrees C and 8 degrees C did not have any effect on granule stability and biomass could be easily retained in the system. The temperature dependency of nitrification was lower for aerobic granules than usually found for activated sludge. Due to decreased activity in the outer layers of granules at lower temperatures, the oxygen penetration depth could increase, which resulted in a larger aerobic biomass volume, compensating the decreased activity of individual organisms. Consequently the denitrifying capacity of the granules decreased at reduced temperatures, resulting in an overall poorer nitrogen removal capacity. The overall conclusion that can be drawn from the experiments at low temperatures is that start-up in practice should take place preferentially during warm summer periods, while decreased temperatures during winter periods should not be a problem for granule stability and COD and phosphate removal in a granular sludge system. Nitrogen removal efficiencies should be optimized by changes in reactor operation or cycle time during this season.

Anoxybacillus kamchatkensis sp. nov., a novel thermophilic facultative aerobic bacterium with a broad pH optimum from the Geyser valley, Kamchatka.

A facultative aerobic, moderately thermophilic, spore forming bacterium, strain JW/VK-KG4 was isolated from an enrichment culture obtained from the Geyser valley, a geo-thermally heated environment located in the Kamchatka peninsula (Far East region of Russia). The cells were rod shaped, motile, peritrichous flagellated stained Gram positive and had a Gram positive type cell wall. Aerobically, the strain utilized a range of carbohydrates including glucose, fructose, trehalose, proteinuous substrates, and pectin as well. Anaerobically, only carbohydrates are utilized. When growing on carbohydrates, the strain required yeast extract and vitamin B(12). Anaerobically, glucose was fermented to lactate as main product and acetate, formate, ethanol as minor products. Aerobically, even in well-aerated cultures (agitated at 500 rpm), glucose oxidation was incomplete and lactate and acetate were found in culture supernatants as by-products. Optimal growth of the isolate was observed at pH(25 C) 6.8-8.5 and 60 degrees C. The doubling times on glucose at optimal growth conditions were 34 min (aerobically) and 40 min (anaerobically). The G+C content was 42.3 mol% as determined by T(m) assay. Sequence analysis of the 16S rRNA gene indicated an affiliation of strain JW/VK-KG4 with Anoxybacillus species. Based on its morphology, physiology, phylogenetic relationship and its low DNA-DNA homology with validly published species of Anoxybacillus, it is proposed that strain JW/VK-KG4 represents a new species in the genus Anoxybacillus as A. kamchatkensis sp. nov. The type strain for the novel species is JW/VK-KG4(T) (=DSM 14988, =ATCC BAA-549). The GenBank accession number for the 16S rDNA sequence is AF510985.

Quantitative analysis of biological effect on membrane fouling in submerged membrane bioreactor.

The objective of this study is to investigate solids concentration and extracellular polymeric substance (EPS) effects on the membrane fouling in the submerged membrane bioreactor. The relationship between the solids retention time (SRT) and the amount of EPS is observed in three lab-scale MBRs. Additionally, the EPS effect on membrane fouling is quantified by calculating the specific cake resistance (alpha) using an unstirred batch cell test. By observing the sludge over a long period under various SRT scenarios, a wide range of EPS and membrane fouling data is obtained. These observations provide sufficient evidence of the functional relationship between SRT, EPS and alpha. As SRT decreases, the amount of EPS bound in sludge floc becomes higher in the high MLSS condition (> 5,000 mg/L). The amount of EPS in the sludge floc has positive influence on alpha. A sigmoid trend between EPS and alpha is observed and the functional relationship obtained by dimensional analysis is consistent with the experimental results.