Average Bacterial Concentration Research Articles

Disruption and recovery of outdoor bioaerosols before, during, and after the COVID-19 outbreak at a campus in Central China: pathogen composition, particle size distribution, influencing factors, and exposure risk.

Before (2019), during (2020), and after (2021) the COVID-19 outbreak, different response methods and measures were taken on campuses to control the spread of COVID-19 within schools. These response methods may have changed the outdoor bioaerosol characteristics, which may affect staff and student health. Therefore, we analyzed the bacterial concentrations, particle size distribution, microbial populations, exposure risks, and environmental influences of bioaerosols at a campus before, during, and after the COVID-19 outbreak. This study used eight-stage Andersen samplers to collect and analyze culturable bacteria in bioaerosols from various locations, high-throughput sequencing to analyze microbial species, principal component analysis to compare differences in samples, RDA to investigate the effects of environmental factors on bioaerosols, and hazard quotient (HQ) and BugBase to evaluate human health risks. The study findings revealed that average bacterial concentrations before, during, and after COVID-19 were 75 CFU m-3, 136 CFU m-3, and 78 CFU m-3, respectively. Moreover, the average percentage of bacteria attached to PM2.5 was 49.2%, 42.7%, and 29.9%, respectively. High-throughput sequencing revealed that species composition changed significantly during the three years of COVID-19. The proportion of Pantoea and Bacillus increased with the development of COVID-19 and these became the dominant strains after COVID-19, whereas Pseudomonas had the maximum proportion during COVID-19. Both risk assessment and BugBase phenotype prediction results indicated that the potential pathogenic risk was the highest in the outdoor environment of the campus during COVID-19 and that bioaerosol contamination was the most severe compared to the outdoor bioaerosol characteristics of the campus recovered after COVID-19.

2170. It takes two to tango: ß-lactam/ß-lactamase inhibitor combinations targeting metallo-ß-lactamase (MBL)- producing Klebsiella pneumoniae.

Abstract Background The emergence of pan drug resistant (PDR) gram-negatives co-producing NDM-1 and CTX-M-15 calls for devising more efficient biocidal regimens. Also, understanding the salient transcriptomic and phenotypic changes that contribute to persistence which aid in pathogen survival is critical to therapeutic preparation in the clinical setting. Methods A 10-day hollow fiber infection model (HFIM) was utilized to simulate humanized β-lactam regimens involving imipenem (IMI) 1g q8h, aztreonam (ATM) 2g q8h, and ceftazidime/avibactam (CAZ/AVI) 2g/500mg alone and in 3-drug combination regimens against a PDR Klebsiella pneumonia isolate co-harboring blaNDM-1 and blaCMY-6, blaCTX-M-15 and blaSHV-2. Static time kills were performed to investigate the interplay between IMI and ATM. At 2h post drug exposure, total RNA was analyzed by qRT-PCR for the expression of pertinent genes. Glutaraldehyde-fixed samples were imaged using fluorescence and scanning electron microscopy. Results In HFIM, IMI contributed synergistically to the antimicrobial action as the average bacterial concentration between 30-120h was 2.1 log10 CFU/mL lower in ATM + CAZ/AVI + IMI than in ATM + CAZ/AVI (2.44 log10 CFU/mL vs. 4.54 log10 CFU/mL, respectively). Adding IMI to ATM+ CAZ/AVI also resulted in an enhanced post-antibiotic effect. Although ATM + IMI reduced bacterial counts by ≥4 log10 CFU/mL in 6h time kill assays, regrowth to the system carrying capacity of ∼8.5 log10 CFU/mL by 24h in all arms rendered these drugs ineffective. By 2h of treatment, ATM alone resulted in long filamentous cells whereas IMI resulted in significant populations of spheroplasts. ATM+IMI caused blebbing in the center of elongating filaments followed by a burst in spheroplast formation. qRT-PCR showed upregulation of spheroplast protein Y (spy) and penicillin binding proteins (pbp1, pbp2, pbp3) for all combinations involving IMI. However, pbp1, pbp3 and spy remained unchanged and pbp2 levels were downregulated by >25% in ATM monotherapy. Conclusion Overall, this PDR clinical isolate persisted in the presence of ATM + CAZ/AVI. The addition of IMI to target PBP2 in β-lactam combinations maximally suppressed the emergence of filamentous persisters and may be a promising strategy to prepare for increasing rates of gram-negative resistance. Disclosures All Authors: No reported disclosures

Airborne particles, bacterial and fungal communities insights of two museum exhibition halls with diverse air quality characteristics

Airborne particles, bacteria and fungi consist main determinants of indoor air quality. In this study, these characteristics were investigated in two exhibition halls of the Historical Museum of Crete, in comparison with the outdoor environment. In Zacharias Portalakis (ZP) hall, three air purifiers were operating during museum opening hours, as opposed to El Greco (EG) hall. A significant part of ultrafine (< 1 μm) particles was efficiently removed by the air purifiers in ZP hall. Airborne coarse particles PN2.5–10 were associated with human occupancy in both halls, indicating transportation from visitors and resuspension as possible sources. Average airborne bacterial concentration was also lower in ZP than in EG hall, assessed by both molecular and culture-dependent methods. The bacterial and fungal communities of both indoor halls were distinct from the outdoor counterpart. Micrococcus and Staphylococcus, in terms of bacteria, and Alternaria and Malassezia, in terms of fungi, were the most abundant genera indoors, most of them being human-related. Hierarchical clustering of indoor samples indicated that EG hall bacteria were similar to ZP hall bacteria collected on the same day, but varied between different sampling dates. This observation, together with the bacterial beta-diversity analysis, implied that both indoor halls probably shared common bacterial source(s), while the respective fungal pattern of the two indoor halls was found significantly separated. The outdoor air contribution in EG and ZP hall bacterial profile presented a comparable fluctuation pattern; this was not observed for fungi, probably indicating the complexity of potential sources for different fungal taxa.

Microbiological Evaluation of Water Used in Dental Units

In modern dentistry, dental units are used for the treatment of patients’ teeth, and they need water to operate. Water circulates in a closed vessel system and finally reaches the mucous membranes of the patient as well as the dentist themselves. Therefore, the microbiological safety of this water should be a priority for physicians. This study aims to identify and determine the microbial count, expressed in CFU/mL, in water samples from various parts of the dental unit that are in direct contact with the patient. Thirty-four dental units located in dentistry rooms were analysed. The dentistry rooms were divided into three categories: surgical, conservative, and periodontal. It was found that in surgical rooms, the bacterial count was 1464.76 CFU/mL, and the most common bacterium was Staphylococcus pasteuri—23.88% of the total bacteria identified. In dentistry rooms where conservative treatments were applied, the average bacterial concentration was 8208.35 CFU/mL, and the most common bacterium was Ralsonia pickettii (26.31%). The periodontal rooms were also dominated by R. pickettii (45.13%), and the average bacterial concentration was 8743.08 CFU/mL. Fungi were also detected. Rhodotorula spp., Alternaria spp., and Candida parapsilosis were found to be the most common bacteria which are potentially harmful. This study indicates the need for effective decontamination of the water that is used in dental units and for constant monitoring of the level of contaminants present in the closed vessel system.

Seawater desalination based drinking water: Microbial characterization during distribution with and without residual chlorine

Monitoring the changes that occur to water during distribution is vital to ensure water safety. In this study, the biological stability of reverse osmosis (RO) produced drinking water, characterized by low cell concentration and low assimilable organic carbon, in combination with chlorine disinfection was investigated. Water quality at several locations throughout the existing distribution network was monitored to investigate whether microbial water quality changes can be identified. Results revealed that the water leaving the plant had an average bacterial cell concentration of 103 cells/mL. A 0.5–1.5 log increase in bacterial cell concentration was observed at locations in the network. The residual disinfectant was largely dissipated in the network from 0.5 mg/L at the treatment plant to less than 0.1 mg/L in the network locations. The simulative study involving miniature distribution networks, mimicking the dynamics of a distribution network, fed with the RO produced chlorinated and non-chlorinated drinking water revealed that distributing RO produced water without residual disinfection, especially at high water temperatures (25–30 °C), poses a higher chance for water quality change. Within six months of operation of the miniature network fed with unchlorinated RO produced water, the adenosine triphosphate (ATP) and total cell concentration (TCC) in the pipe biofilm were 4 × 102 pg ATP/cm2 and 1 × 107 cells/ cm2. The low bacterial cell concentration and organic carbon concentration in the RO-produced water did not prevent biofilm development inside the network with and without residual chlorine. The bacterial community analysis using 16S ribosomal RNA (rRNA) gene sequencing revealed that mesophilic bacteria with higher temperature tolerance and bacteria associated with oligotrophic, nutrient-poor conditions dominated the biofilm, with no indication of the existence of opportunistic pathogenic species. However, chlorination selected against most bacterial groups and the bacterial community that remained was mainly the bacteria capable of surviving disinfection regimes. Biofilms that developed in the presence of chlorine contained species classified as opportunistic pathogens. These biofilms have an impact on shaping the water quality received at the consumer tap. The presence of these bacteria on its own is not a health risk indicator; viability assessment and qPCRs targeting genes specific to the opportunistic pathogens as well as quantitative microbiological risk assessment (QMRA) should be included to assess the risk.The results from this study highlight the importance of implementing multiple barriers to ensure water safety. Changes in water quality detected even when high-quality disinfected RO-produced water is distributed highlight microbiological challenges that chlorinated systems endure, especially at high water temperatures.

Bacteria bioaerosol in the indoor air of educational microenvironments: Measuring exposures and assessing health effects.

Exposure to bioaerosols has been identified to be linked the incidence of various health effects, i.e., infectious diseases, acute toxic effects, allergies, and cancer. The aim of this study was to determine the bacterial bioaerosols in the indoor air of the educational environments of Ardabil universities and to evaluate the exposure and to determine its health risk. In this cross-sectional study, different sections of the educational environments of Ardabil universities were studied. For differential diagnosis of bacteria, methods such as gram staining and biochemical detection methods including DNAse, catalase, oxidase, coagulase, bile esculin hydrolysis test, urease, citrate test, antibiotic resistance to novobiocin and Bacitracin, optochin, glucose uptake, and other differential tests were used. For sampling, a single-stage Anderson sampler was used at a flow rate of 28.3l at a duration of 10min per minute. The results showed that, in medical school of Ardabil University of Medical Sciences, the average concentration of bacteria in the outdoor air of school, halls, classes and rooms of professors and staff were 18, 88.4, 76.6, and 77.4CFU/m3, respectively, and, in Ardabil Islamic Azad University, the average bacterial concentration was 103, 97, 124, and 132CFU/m3 in the outdoor air of the schools, halls, classrooms, and rooms of professors and staff, respectively. The predominant bacterial species in indoor air are S. aureus, S. epidermidis, Actinomycetes, and Bacillus, respectively. As results indicated, the concentration of bacterial bioaerosols in indoor air is within the standard levels, but due to frequency of bacterial species, occurrence of different in lung and intestinal diseases can be expected among faculty, staff and students in the long-term.

Detection of microbial aerosols in hospital wards and molecular identification and dissemination of drug resistance of Escherichia coli

Antibiotic-resistant bacteria (ARB) present a global public health problem. Microorganisms are the main cause of hospital-acquired infections, and the biological contamination of hospital environments can cause the outbreak of a series of infectious diseases. Therefore, it is very important to understand the spread of antibiotic-resistant bacteria in hospital environments. This study examines the concentrations of aerobic bacteria and E. coli in ward environments and the airborne transmission of bacterial drug resistance. The results show that the three wards examined have an average aerobic bacterial concentration of 132 CFU∙m−3 and an average inhalable aerobic bacterial concentration of 73 CFU∙m−3, with no significant difference (P > 0.05) among the three wards. All isolated E. coli showed multi-drug resistance to not only third-generation cephalosporin antibiotics, but also quinolones, aminoglycosides, and sulfonamides. Furthermore, 51 airborne E. coli strains isolated from the air in the three wards and the corridor were screened for ESBLs, and 12 (23.53%) were ESBL-positive. The drug-resistance gene of the 12 ESBL-positive strains was mainly TEM gene, and the detection rate was 66.67% (8/12). According to a homology analysis with PFGE, 100% homologous E. coli from the ward at 5 m and 10 m outside the ward in the corridor shared the same drug-resistance spectrum, which further proves that airborne E. coli carrying a drug-resistance gene spreads out of the ward through gas exchange. This leads to biological pollution inside, outside, and around the ward, which poses a direct threat to the health of patients, healthcare workers, and surrounding residents. It is also the main reason for the antibiotic resistance in the hospital environment. More attention should be paid to comprehensive hygiene management in the surrounding environment of hospitals.

A within-flock model of Salmonella Heidelberg transmission in broiler chickens

As part of the development of a quantitative microbial risk assessment (QMRA) model of third-generation cephalosporins (3GC)-resistant Salmonella Heidelberg, a compartmental (SEIR) model for S. Heidelberg transmission within a typical Canadian commercial broiler chicken flock was developed. The model was constructed to estimate the within-flock prevalence and the bacterial concentration in the barn environment at pre-harvest, and to assess the effect of selected control measures.The baseline scenario predicted an average within-flock prevalence of 23.5 % (95 % tolerance interval: 15.7–31.4) and an average bacterial concentration of 3.579 (0–4.294) log CFU/g of feces in the barn environment at pre-harvest (on the day the flock is sent to slaughter). Because vertical introduction of S. Heidelberg into the barn was already uncommon in the baseline scenario, vaccination of broiler parent flocks appeared to have a negligible effect, while vaccination of broiler chicken flocks substantially reduced the bacterial concentration at pre-harvest. Cleaning and disinfection between batches markedly reduced the within-flock prevalence at pre-harvest, but the effect on bacterial concentration was limited outside of the beginning of the production period. Extending downtime between batches by 7 days had little effect on within-flock prevalence or bacterial concentration of S. Heidelberg when compared to the baseline scenario.This study provides a basis to describe S. Heidelberg dynamics within a broiler chicken flock and to predict the within-flock prevalence and bacterial concentration at pre-harvest, and includes a description of the limitations and data gaps. The results of these analyses and associated uncertainties are critical information for populating QMRA models of the downstream impacts on public health from on-farm and other food-chain practices. Specifically, the study findings will be integrated into a broader farm-to-fork QMRA model to support the risk-based control of S. Heidelberg resistant to 3GC in broiler chicken in Canada.

Microbial contamination level and microbial diversity of occupational environment in commercial and traditional dairy plants.

The aim of this study was to assess microbial contamination of the air and surfaces at workplaces in commercial (CD) and traditional (TD) dairies. Bioaerosol (impactor) and surface (swab) samples were collected in CD and in TD. Bacterial and fungal concentrations in the air and on surfaces were calculated and all isolated microorganisms taxonomically identified, based on their morphological, biochemical and molecular features. Average concentrations of bacterial aerosol ranged between 70-860 CFU/m3 and 265-14639 CFU/m3, while for fungal aerosol were between 50-290 CFU/m3 and 55-480 CFU/m3 in CD and TD, respectively. Average bacterial concentrations on surfaces ranged between 1.0-49.7 CFU/cm2 and 0.2-60.4 CFU/cm2, whereas average fungal surface contamination ranged between 0-2.7 CFU/cm2 and 0-4.6 CFU/cm2 in CD and TD, respectively. Qualitative analysis revealed mainly the presence of saprophytic microorganisms; however, several pathogenic strains (Staphylococcus aureus, Streptococcus intermedius, Clostridium perfringens, Actinomyces spp., Streptomyces spp., Candida albicans) were also isolated from both the air and surface samples in the studied dairies. The air and surfaces in TD were more polluted than those in CD; however, in both types of dairies, the levels of microbial contaminants did not exceed respective threshold limit values. Nevertheless, the presence of pathogenic microorganisms may increase health risk for dairy workers and influence the quality of products. Hence, proper hygienic measures should be introduced and performed to guarantee high microbial quality of both production processes and milk products.

Spatial variability and evaluation of airborne bacteria concentration in manure belt poultry houses

Manure belt poultry houses were widely used for egg production. However, reliable spatial distribution of airborne bacteria data from long-term on-farm monitoring in manure belt houses are scarce. In this study, the airborne bacteria were collected by the Andersen air microorganism sampler in a 4 tiers and an 8 tiers layer house, respectively. Results revealed that the airborne bacteria concentration range from 565 ± 247 CFU/m3 to 12,118 ± 883 CFU/m3 inside the 4 tiers poultry farmhouse and 459 ± 247 to 12,966 ± 884 CFU/m3 inside 8 tiers poultry farmhouse, respectively. The average airborne bacterial concentrations in the 4 and 8 tiers manure belt houses were 4,527 ± 2,509 and 5,489 ± 2,579 CFU/m3, respectively. Significant spatial variations of airborne bacteria concentration were observed for both houses. Spatial distribution of airborne bacteria concentration along the long axis direction can be divided into 3 regions: the low concentration region (<6,000 CFU/m3), the transition region (6,000-10,000 CFU/m3), and the high concentration region (>10,000 CFU/m3), and airborne bacteria concentration was symmetrically distributed along the short axis direction inside both houses. We used 5 and 3 sampling locations to assess the average and maximum airborne bacterial concentration inside the manure belt houses, respectively. The average airborne bacteria concentration of 3 sampling locations was closest to the maximum concentration of both houses. It is more useful to use 3 sampling locations to monitor the change of the maximum airborne bacterial concentration inside the manure belt houses.

Peculiarities of Bacterial Chemotaxis in a Cylindrical Pore

The process of bacterial redistribution in a cylindrical pore filled with an attractant has been considered. The attractant concentration decreases linearly along the pore, and the redistribution of bacteria occurs due to their diffusion (the motion of bacteria along the gradient of their concentration) and chemotaxis (the motion of bacteria along the gradient of attractant concentration). The influence of a spatial confinement on the bacterial distribution in the pore is analyzed. It is shown that if the pore wall is “repelling” for bacteria, the spatial confinement can change the bacterial distribution. In particular, as the pore radius decreases, the chemotaxic effect becomes weaker. The non-uniformity of a bacterial distribution in the system is estimated. The chemotaxis sensitivity function (the deviation of the ratio between the local average bacterial concentration and the average bacterial concentration over the whole system from unity) is calculated, and its dependence on the attractant concentration at the system ends and on the pore size is determined.

Anaerobic bacteria in wastewater treatment plant

PurposeThe objective of this study was to assess exposure to anaerobic bacteria released into air from sewage and sludge at workplaces from a wastewater treatment plant (WWTP).MethodsSamples of both sewage and sludge were collected at six sampling points and bioaerosol samples were additionally collected (with the use of a 6-stage Andersen impactor) at ten workplaces covering different stages of the technological process. Qualitative identification of all isolated strains was performed using the biochemical API 20A test. Additionally, the determination of Clostridium pathogens was carried out using 16S rRNA gene sequence analysis.ResultsThe average concentration of anaerobic bacteria in the sewage samples was 5.49 × 104 CFU/mL (GSD = 85.4) and in sludge—1.42 × 106 CFU/g (GSD = 5.1). In turn, the average airborne bacterial concentration was at the level of 50 CFU/m3 (GSD = 5.83) and the highest bacterial contamination (4.06 × 103 CFU/m3) was found in winter at the bar screens. In total, 16 bacterial species were determined, from which the predominant strains belonged to Actinomyces, Bifidobacterium, Clostridium, Propionibacterium and Peptostreptococcus genera. The analysis revealed that mechanical treatment processes were responsible for a substantial emission of anaerobic bacteria into the air. In both the sewage and air samples, Clostridium perfringens pathogen was identified.ConclusionsAnaerobic bacteria were widely present both in the sewage and in the air at workplaces from the WWTP, especially when the technological process was performed in closed spaces. Anaerobic bacteria formed small aggregates with both wastewater droplets and dust particles of sewage sludge origin and as such may be responsible for adverse health outcomes in exposed workers.

Concentration and size distribution of biological particles in school classrooms

Fungal and bacterial aerosol particles concentrations are measured in a school classrooms at two different floors using the 6-stage Andersen impactor as a bioaersol sampler. The average bacterial concentration is higher than the average fungal concentration. The concentrations were 957 and 955 cfu/m3 for bacterial particles at first and second floors, respectively while the fungal particles concentrations were 146 and 235 cfu/m3 at first and second floors, respectively. Most of the biological particles were concentrated at the size range of respirable particles (&lt; 5 µm ) that can penetrate into the alveoli and may cause lung diseases. The human activity is a main factor for the production of microbiological particles. Environmental factors play also a role on the fungal growth. Bacterial concentration is almost twice the guide value of WHO while the fungal concentration is underestimation.

Adherence of Pseudomonas aeruginosa onto surfactant-laden contact lenses

There is an immense research interest to utilise contact lens (CLs) as a popular platform for ocular drug delivery. However, CLs are the major predisposing factors of bacterial keratitis which is commonly caused by adhesion of microbes such as Pseudomonas aeruginosa and Staphylococcus epidermidis. The aim of the current study is to explore the effect of surfactants; Poloxamer 188, Polysorbate 80 and Tetronic® 90R4 (at 0.25% – 3% v/v) on the characteristics of CLs and on the adhesion abilities of Pseudomonas aeruginosa to the lenses’ surfaces. CLs were formulated using a hydrophilic monomer; 2-hydroxyethyl methacrylate (HEMA) together with silicone-based polymer such as Poly dimethyl siloxane (PDMS) or 3,3,3-trifluoropropylsilane (FSA) then lenses were polymerized under UV light. The formulated CLs with surfactants were found to have an increased equilibrium water content (EWC) due to hydrophilic moiety present in surfactants. A relationship was deduced between EWC and surface contact angle of lenses containing surfactants; where an increased EWC was associated with a decrease in contact angle reflecting a more hydrophilic surfaces of CLs. Apart from the 3% Polysorbate 80 (p < .0001) CLs, all other formulations had light transmission values over 80%. Lenses with surfactants were found to have lower bacterial ATP concentration than lenses without surfactants. Poloxamer 188 in FSA lenses reduced bacterial adhesion from 4.22 × 10−4 ± 1.30 × 10−4 pM to 1.03 × 10−4 ± 4.86 × 10−5 pM, a reduction by 75.59% when compared to the control lenses (p = .002). Moreover, 1% Tetronic® 90R4 in PDMS showed a reduction by 57.17% in ATP concentration. Polysorbate 80 in FSA exhibited the least bacterial adhesion with an average bacterial ATP concentration of 3.85 × 10−5 ± 2.61 × 10−5 pM; i.e 90.88% less bacterial ATP than control lenses (p = .001). Bioluminescence studies demonstrated a decrease in Pseudomonas aeruginosa adhesion to CLs containing surfactants without impairing the optical and mechanical characteristics of the lenses.

PENGGUNAAN PERASAN JERUK NIPIS (Citrus aurantifolia) DALAM MENGHAMBAT BAKTERI Escherichia coli PADA BAHAN PANGAN

Bacteria in food can result from the sale of foods that do not pay attention to hygiene and safety. Pathogenic bacteria in food can cause illness gastroenteris/digestion. One of the ways to prevent the escape of pathogens is antibacterial compounds . Lemon (Citrus aurantifolia) contained many chemical compounds that can inhibit the growth of bacteria such as flavonoids and saponin. This study aims to isolate bacteria from food such as fish and chicken as a test of the effectiveness of lemon on the growth of bacteria. The study was conducted on April 2016 in MIPA (Science) Laboratory of UIN Raden Fatah Palembang and the Center for Health Laboratory Palembang. The research method is experimental laboratory used as a pour plate in order to make the diffusion were analyzed qualitatively. Using test bacteria Escherichia coli from food that is tested by agar diffusion method for determining the concentration of lemon juice on the growth of bacteria. The results showed that lemon juice can inhibit the growth of E. coli bacteria that is at a concentration of 25% average of 3,2 colonies of bacteria/gram; 50% mean bacterial concentration of 2,4 colonies/gram; 7% of the average bacterial concentration of 4,2% and 100% means bacterial concentration of 0,8 colonies/gram. Lemonsqueezemost effectively inhibits bacteria at concentrations of 100%.

Microbial Air Contamination in an Intensive Care Unit

Unit layout affects every aspect of intensive care services, including patient safety. A previous study has shown that patients admitted to beds adjacent to the sink and to the door of a large bayroom had the highest number of positive blood cultures and the highest blood culture incidence density, respectively. The present study measures microbial air contamination in a medical intensive care unit of a medical center in central Taiwan. Of the 17 rooms, 8 rooms with distinct physical environmental characteristics were selected. Sampling tests were conducted between December 2013 and February 2014 with a microbial air sampler (MAS-100NT). TSA was used for bacteria collection and DG18 for fungi collection. The overall average bacterial and fungal concentrations were 83CFU/m&lt;sup&gt;3&lt;/sup&gt; and 69CFU/m&lt;sup&gt;3&lt;/sup&gt;, respectively. The ranges were between 8-354 CFU/m&lt;sup&gt;3&lt;/sup&gt; and 0-1468 CFU/m&lt;sup&gt;3&lt;/sup&gt;, respectively. A significant difference was found in the bacterial concentration (p=.005) between different room locations. The highest concentration was found in the rooms located at the front end of the circulation (99 CFU/m&lt;sup&gt;3&lt;/sup&gt;), while the lowest was found in the rooms located at the rear end of the circulation (55CFU/m&lt;sup&gt;3&lt;/sup&gt;). Differences in fungal concentrations for different room locations did not reach statistical significance. In addition, differences in bacterial and fungal concentrations for rooms with different sink locations did not reach statistical significance. Even though the microbial concentrations generally complied with standards, the results may help designers and hospital administrators develop a healthier environment for patients.

Microbial Air Contamination in an Intensive Care Unit

Unit layout affects every aspect of intensive care services, including patient safety. A previous study has shown that patients admitted to beds adjacent to the sink and to the door of a large bayroom had the highest number of positive blood cultures and the highest blood culture incidence density, respectively. The present study measures microbial air contamination in a medical intensive care unit of a medical center in central Taiwan. Of the 17 rooms, 8 rooms with distinct physical environmental characteristics were selected. Sampling tests were conducted between December 2013 and February 2014 with a microbial air sampler (MAS-100NT). TSA was used for bacteria collection and DG18 for fungi collection. The overall average bacterial and fungal concentrations were 83CFU/m&lt;sup&gt;3&lt;/sup&gt; and 69CFU/m&lt;sup&gt;3&lt;/sup&gt;, respectively. The ranges were between 8-354 CFU/m&lt;sup&gt;3&lt;/sup&gt; and 0-1468 CFU/m&lt;sup&gt;3&lt;/sup&gt;, respectively. A significant difference was found in the bacterial concentration (p=.005) between different room locations. The highest concentration was found in the rooms located at the front end of the circulation (99 CFU/m&lt;sup&gt;3&lt;/sup&gt;), while the lowest was found in the rooms located at the rear end of the circulation (55CFU/m&lt;sup&gt;3&lt;/sup&gt;). Differences in fungal concentrations for different room locations did not reach statistical significance. In addition, differences in bacterial and fungal concentrations for rooms with different sink locations did not reach statistical significance. Even though the microbial concentrations generally complied with standards, the results may help designers and hospital administrators develop a healthier environment for patients.

Bacteriological quality of effluent submitted consecutively to a macrofiltration and ultraviolet light systems in the Tunisian conditions.

This paper deals with the study of bacteriological quality of effluents that have undergone consecutively different macrofiltration system (pressure sand filter or disc filter used as a secondary treatment) and UV254 irradiation process (used as a tertiary treatment). These two successive systems of treatment were evaluated to determine their possible application as commonly alternatives to the conventional system of wastewater treatment and disinfection before wastewater reuse. They both combined systems of wastewater treatment released effluent of excellent bacteriological quality, with almost total absence of feacal coliforms, of E. coli and of P. aeruginosa). However, if the bacteriological quality of the effluent remained constant in the case of macrofiltration system (disc filter or pressure sand filter); the UV disinfection process showed to deeply depend on the quality of effluent, particularly with regard to UV transmittance. The daily bacteriological monitoring of the secondary effluent at the exit of the pressure sand filter by UV reactor and by using a dose of 96 mJ/cm2, corresponding to an exposure of 16 min, showed an average rate of inactivation of around 3 U-Log, for feacal coliforms, E. coli and P. aeruginosa, respectively. Therefore, the average bacterial concentration remaining in the water at the exit of the UV reactor is less than 1000 cfu/100 ml for feacal coliform and E. coli. For P. aeruginosa, the remaining number is less than 100 bacteria/100 ml. These two last values coincide substantially with the range recommended by several standardized international guidelines. Therefore, numerous authors reported that P. aeruginosa is very resistant to UV irradiation compared to the other bacterial indicators. In contrast, our study revealed that feacal coliforms and E. coli were more UV light resistant than P. aeruginosa. This finding could be explained by the fact that E. coli and feacal coliform forms aggregates in the treated effluent, while P. aeruginosa exists either as discrete cells or as cell pairs.

Quantitative microbial risk assessment of bioaerosols from a manure application site

Bioaerosol concentrations and deposition were monitored at the edge of a dairy manure application site in northern New York State. Total bacteria, fecal indicator bacteria (Enterococcus spp. and Escherichia coli), and select bacterial pathogens (Salmonella spp., Campylobacter spp., and E. coli O157:H7) were measured in the manure and air by real-time quantitative PCR (qPCR). The 8-h average bacterial air concentration measured by liquid impingement following manure application was 7.89 × 105 copies m−3, one order of magnitude greater than mean background measurements (6.35 × 104 copies m−3; n = 6). Eight-hour ambient concentration of Enterococcus spp. was 1.54 × 104 copies m−3; E. coli and pathogens were less than their respective limits of detection. The measured deposition flux of bacteria was 1.08 × 103 copies m−2 s−1, corresponding to bulk deposition velocity of 0.15 cm s−1. Using inverse dispersion modeling with the US Environmental Protection Agency’s AERMOD, the emission of bacteria from the manure-amended field was estimated to be 1.27 × 105 copies m−2 s−1. AERMOD was also used to model downwind bioaerosol concentrations; the greatest modeled 8-h average downwind bacteria concentrations were 8.00 × 105 copies m−3 above background at 100 m and 3.95 × 103 copies m−3 above background at 1,000 m. Potential health risks associated with these bioaerosols were estimated by quantitative microbial risk assessment based on AERMOD results using measured pathogen concentrations in land-applied manure and emission rate estimates for total bacteria. Median risks of infection over an 8-h exposure period were 1:500 at 100 m and 1:100,000 at 1,000 m; peak risks (95th percentile) were 1:250 and 1:50,000, respectively.

Airborne Microorganisms at a Senior High School in Chang-Hua County, Taiwan

Bioaerosols are a type of suspended sediments that contribute to poor air quality in Taiwan. Bioaerosols include allergens such as fungi, bacteria, actinomycetes, arthropods, and protozoa, as well as microbial products such as mycotoxins, endotoxins and glucans. When allergens and microbial products are suspended in the air, local air quality is adversely influenced. In addition, when the particle size is small enough to pass through the human respiratory tract, the health of the local population is also threatened. The classroom is where students spend a large portion of weekday time and thus could play an important role in student's exposure to potential threatening bioaerosols. The purpose of this study was to understand the airborne bacteria and fungi concentrations at a sampling classroom (with the windows opened and closed) from a senior high school in Chang-Hua County, Taiwan. The results indicate that the total average bacterial concentrations were 2.2 × 103, 1.7 × 103, 7.8 × 102, 1.2 × 103, 7.4 × 102 and 7.6 × 102 cfu/m3 using tryptic soy agar (TSA)-medium incubated for 48 hr under various sampling conditions in the morning, afternoon, and evening with windows closed and opened, respectively (i.e., morning with windows closed [MC], afternoon with windows closed [AC], evening with windows closed [EC], morning with windows opened [MO], afternoon with windows opened [AO], and evening with windows opened [EO]) at the sampling classroom. Moreover, the total average fungi concentrations were 1.1×103, 7.3×102, 6.3×102, 7.4×102, 5.8×102, and 6.2×102 cfu/m3 using malt extract agar (MEA) medium incubated for 96 hr under the same various sampling conditions (MC, AC, EC, MO, AO, and EO). The total average bacterial and fungi concentrations were higher with windows closed than with windows opened during any sampling period. Ventilation is the possible reason for the above finding. The highest average bacterial or fungi concentrations was found in the particle size of 0.53 mm (average bioaerosol size was in the range of 2.1–3.3 μm) for any sampling condition. These findings may be relevant in a forensic investigation related to a potential bioattack, since it provides baseline information of bioaerosols composition (e.g., before an attack is initiated) within the tested environment.