Assessment of the bacterial contamination of hand air dryer in washrooms

The present study was carried out, using standard techniques, to identify and count the bacterial contamination of hand air dryers, used in washrooms. Bacteria were isolated from the air flow, outlet nozzle of warm air dryers in fifteen air dryers used in these washrooms. Bacteria were found to be relatively numerous in the air flows. Bacterially contaminated air was found to be emitted whenever a warm air dryer was running, even when not being used for hand drying. Our investigation shows that Staphylococcus haemolyticus, Micrococcus luteus, Pseudomonas alcaligenes, Bacillus cereus and Brevundimonad diminuta/vesicularis were emitted from all of the dryers sampled, with 95% showing evidence of the presence of the potential pathogen S. haemolyticus. It is concluded that hot air dryers can deposit pathogenic bacteria onto the hands and body of users. Bacteria are distributed into the general environment whenever dryers are running and could be inhaled by users and none-users alike. The results provide an evidence base for the development and enhancement of hygienic hand drying practices.     

Improved Template Preparation for PCR-Based Assays for Detection of Food-Borne Bacterial Pathogens

Shigella flexneri, Salmonella enterica serotype Typhimurium, and Listeria monocytogenes were applied to FTA filters, and the filters were used directly as templates to demonstrate their sensitivity and applicability in PCR-based detection assays. With pure cultures, the sensitivities of detection by FTA filter-based PCR were 30 to 50 and 200 CFU for the gram-negative enterics and Listeria, respectively. Different numbers of S. flexneri cells were used in controlled contamination experiments with several different foods (produce, beef, and apple cider). Aliquots from concentrated food washes subsequently spotted onto FTA filters and assayed by PCR gave consistently positive results and detection limits similar to those observed with pure-culture dilutions. This universal method for PCR template preparation from bacterial cells is rapid and highly sensitive and reduces interference from food-associated inhibitors of PCR. In addition, its broad applicability eliminates the need for multiple methods for analysis of food matrices.     

The age of hair matters – the incorporation of cortisol by external contamination is enhanced in distal hair segments of pigs and cattle

Hair cortisol concentration (HCC) is used as an indicator of long-term stress or pathologies in humans and increasingly in animals. Although the main mechanism for the incorporation of cortisol into the hair shaft is by diffusion from blood, cortisol may also be incorporated from external sources by contamination of the hair surface. In farm animals under conventional husbandry conditions and trapped animals, contamination of hair with cortisol-containing body fluids, especially with urine, was shown to be a considerable confounding factor when studying HCCs. We recently found that cattle and pigs exhibit elevated HCCs in distal hair segments and assume that the incorporation of external cortisol is facilitated in these older hair segments. Therefore, the aim of this study was to investigate the effects of urine contamination on HCC in different hair segments of pigs and cattle, and to determine whether different cleaning protocols can prevent contamination effects. In an in vivo experiment in pigs (n = 18) and an in vitro experiment in cattle (n = 12), hairs were repeatedly contaminated with urine of the respective species and then shaved or cut in segments. Cortisol concentrations in hair segments were analysed by enzyme immunoassay after washing with isopropanol and extraction with methanol. Results were compared with HCCs in untreated hairs or hairs treated with water. Moreover, additional bovine hair samples contaminated with urine were subjected to two further cleaning procedures. Contamination with urine generally increased HCCs, and it was demonstrated for the first time that this effect is more pronounced in distal compared to proximal hair segments in both species. The immersion of bovine hair in vitro in water caused a washout of cortisol, which was also more pronounced in distal hair segments. In general, the different cleaning protocols for cattle hair did not prevent contamination effects, so we assume that external cortisol not only adheres but is incorporated into the hair shaft. Structural damage of older, distal hair segments may facilitate permeability of the hair matrix and diffusion of cortisol from and into aqueous solutions. Thus, the validity of HCC as a marker of stress is compromised in animals where soiling of hair with body fluids is a risk factor. Therefore, hair samples should be collected from clean body regions and, if possible, using proximal hair segments.     

Comparative evaluation of the hygienic efficacy of an ultra-rapid hand dryer vs conventional warm air hand dryers

Aims: To compare an ultra‐rapid hand dryer against warm air dryers, with regard to: (A) bacterial transfer after drying and (B) the impact on bacterial numbers of rubbing hands during dryer use. Methods and Results: The Airblade? dryer (Dyson Ltd) uses two air ‘knives’ to strip water from still hands, whereas conventional dryers use warm air to evaporate moisture whilst hands are rubbed together. These approaches were compared using 14 volunteers; the Airblade? and two types of warm air dryer. In study (A), hands were contaminated by handling meat and then washed in a standardized manner. After dryer use, fingers were pressed onto foil and transfer of residual bacteria enumerated. Transfers of 0–10⁷ CFU per five fingers were observed. For a drying time of 10 s, the Airblade? led to significantly less bacterial transfer than the other dryers (P < 0·05; range 0·0003–0·0015). When the latter were used for 30–35 s, the trend was for the Airblade to still perform better, but differences were not significant (P > 0·05, range 0·1317–0·4099). In study (B), drying was performed ± hand rubbing. Contact plates enumerated bacteria transferred from palms, fingers and fingertips before and after drying. When keeping hands still, there was no statistical difference between dryers, and reduction in the numbers released was almost as high as with paper towels. Rubbing when using the warm air dryers inhibited an overall reduction in bacterial numbers on the skin (P < 0·05). Conclusions: Effective hand drying is important for reducing transfer of commensals or remaining contaminants to surfaces. Rubbing hands during warm air drying can counteract the reduction in bacterial numbers accrued during handwashing. Significance and Impact of the Study: The Airblade? was superior to the warm air dryers for reducing bacterial transfer. Its short, 10 s drying time should encourage greater compliance with hand drying and thus help reduce the spread of infectious agents via hands.     

Pyrosequencing analysis of bacterial communities in drinking water biofilters receiving influents of different types

Biological activated carbon (BAC) filters are commonly used in the world for improvement of drinking water quality. The indigenous microbiota in BAC filters can play a crucial role in reduction or biotransformation of contaminants. Molecular analysis can enhance our understanding of ecological functions of the microbial communities in drinking water BAC filters. In this study, three laboratory-scale drinking water BAC filters receiving influents of different types were constructed. Differences of bacterial communities in the three BAC filters were characterized using 454 pyrosequencing analysis. Pyrosequencing analysis illustrated the usefulness in elucidating the bacterial community structure in drinking water biofilter. High bacterial diversity in granular activated carbon (GAC) samples from each BAC biofilter was observed. Proteobacteria was the largest bacterial phylum in each GAC sample, with a marked shift of the proportions of Alpha-, Beta-, and Gammaproteobacteria. The levels of dissolved organic carbon and ammonia nitrogen in the influents could affect the bacterial diversity and community composition in the BAC biofilters. This work might add some new insights into microbial community and its influential factors in drinking water biofilters.     

Firm adherence of Staphylococcus aureus and Staphylococcus epidermidis to human hair and effect of detergent treatment

Staphylococcus aureus and S. epidermidis are common pathogens in hospitals, and care should be taken not to disseminate these organisms among patients. We have focused on human hair as a source of bacterial contamination. We treated hair with culture solutions of S. aureus and S. epidermidis, and then performed scanning electron microscopy. Bacteria were detected on the surface of the cuticles of the hair, and the attached bacteria were not completely removed even by repeated washing with detergents. These results suggested that hair could be a source of bacterial contamination and indicated the importance of decontamination of hair.     

Fecal bacterial contamination in natural water reservoirs as an indicator of seasonal infection by Opisthorchis viverrini in snail intermediate hosts

Opisthorchis viverrini, a carcinogenic liver fluke, requires Bithynia snails as the first intermediate host, which release cercariae after ingesting fluke eggs from contaminated water. Fecal bacterial contamination and O. viverrini-infected Bithynia snails were investigated in samples collected from natural water reservoirs in Ban Phai, Chonnabot and Muang Districts (Ban Lerngpeuy) in Khon Kaen Province, northeast Thailand, where there is a high incidence of cholangiocarcinoma. Water was sampled and examined six times (February, April, June, August, October and December 2006). The most probable number (MPN) index and coliform counts were utilized to evaluate fecal contamination; the cercarial shedding method was conducted for detecting infected snails. The data revealed that all water samples had a high MPN index number, and fecal coliform levels above the WHO standard. This indicated that water in these reservoirs was contaminated with feces or manure constituents. Water sampling from Ban Lerngpeuy showed full-scale bacterial contamination (> 1609 MPN index) throughout the year. This finding was correlated with the highest prevalence of O. viverrini-infected snails, which were found nearly all year round in this area. Slightly lower fecal contamination levels were detected in water samples from Chonnabot and Ban Phai, with high MPN index numbers and coliform counts from April to October. This corresponded with the higher recovery of infected snails in June and August, but with relatively lower prevalence than those found in Ban Lerngpeuy. Among the sampling sites, the people in Ban Lerngpeuy live nearer to the reservoir than do those in Ban Phai and Chonnabot. These results indicate that fecal bacterial contamination in natural water reservoirs is an important indicator of seasonal transmission of O. viverrini eggs to snail intermediate hosts. Sanitation improvement is essential and future investigations on the sources of contamination are needed.     

Bacterial community shift revealed Chromatiaceae and Alcaligenaceae as potential bioindicators in the receiving river due to palm oil mill effluent final discharge

A thorough outlook on the effect of palm oil mill effluent (POME) final discharge towards bacterial community dynamics in the receiving river is provided in this study by using a high-throughput MiSeq. The shift of bacterial composition could be used to determine the potential bacterial indicators to indicate contamination caused by POME. This study showed that the POME final discharge did not only alter the natural physicochemical properties of the river water but also caused the reduction of bacterial diversity in the receiving river. The Chromatiaceae and Alcaligenaceae which were not detected in the upstream but were detected in the downstream part of the river are proposed as the indicator bacteria to indicate the river water contamination caused by POME final discharge. The emergence of either one or both bacteria in the downstream part of the river were shown to be carried over by the effluent. Therefore, an accurate pollution monitoring approach using bacterial indicator is expected to complement the conventional POME pollution assessment method which is currently dependent on the physicochemical properties of the final discharge. This is the first study that reported on the potential indicator bacteria for the assessment of river water contamination caused by POME final discharge.     

Survey of Aspergillus section Flavi and aflatoxin B1 in brewer’s grain used as pig feedstuff in Córdoba, Argentina

Brewing industry by-products are important animal feedstuff alternatives for local swine producers in Córdoba, Argentina. The high content of nutrients makes these by-products vulnerable to bacterial and fungal contamination. The objectives of the present study were (1) to determine the presence of Aspergillus section Flavi in brewer’s grain used to feed pigs and (2) to evaluate the incidence of aflatoxin B₁ in the substrate. Total fungal count of most samples exceeded the levels proposed as feed quality limits, and most Aspergillus section Flavi strains found were able to produce high amounts of AFB₁ in vitro. However, the incidence of AFB₁ was low. The presence of contamination by aflatoxicogenic species in feedstuff might affect the productivity of swine producers and indirectly represents a public health issue.     

Bacteriology of Air-Conditioning Ducts with Special Reference to Operating Rooms

The number of bacteria in air, before filtration with five different easily available filters in the low positive-pressure type of airconditioning system of the Winnipeg General Hospital, was between 3 and 4/cu. ft., and after filtration between 1 and 2/cu. ft. with all types of filters. Cl. welchii contributed about 1% and Staph. pyogenes about 0.1% of this total. Sampling the exhaust air from an operating room during an operation showed that the bacterial count fluctuated with the degree of activity in the room and was from two to 10 times as high as in the air delivered to the room.Atlhough every reasonable attempt should be made to diminish the bacterial count of air in hospitals, if much energy and money is to be spent it would probably be wiser to investigate sources of hospital infection other than the type of air-conditioning system described in this report.     

Is Tillandsia capillaris an efficient bioindicator of atmospheric metal and metalloid deposition? Insights from five months of monitoring in an urban mining area

Atmospheric pollution in megacities has a major impact on human health and environmental quality. Air quality bioindicators may have some advantages over standard devices such as impactors or filters. In this study we evaluated the reliability of Tillandsia sp. versus passive filters for monitoring the atmospheric deposition of metal(loid)s in an area affected by anthropogenic activities. We aimed to gain insight into the composition and origin of atmospheric particles and their fate after deposition on the plant. Three zones with different contamination levels were monitored for five months in 2012. For the highly contaminated area, a linear increase in metal(loïd) accumulation was found in passive filters, whereas for transplanted Tillandsia capillaris the increase was almost linear for As, Cd, Hg, and Sn, but not for Ag, Pb, Sb, and Zn. For the moderately contaminated zone, the results showed that the exposure time was not sufficient for metal(loid) concentrations to increase in either the plants or filters. However, natural specimens provided some indications of the levels of metal contamination. Metal particles were observed on the plant surface and also in the central disc underneath tillandsia trichomes, suggesting that this is a possible pathway for metals to enter the plant. X-ray absorption spectroscopy demonstrated chemical transformation for Pb and As, both in filters and plants. For Pb, sorbed Pb and/or cell wall complexes were identified in the plants. No As^III-S species, indicative of As detoxification, were identified in the plant. Arsenic was oxidized from As^III to As^V in both plants and filters. Thus, in the present study, passive filters proved more reliable than T. capillaris transplants, although natural specimens provided some insights into local contamination. Particulate contaminants underwent chemical transformation after being trapped in the plant, but there was no clear evidence of internalization and detoxification.     

Bacterial diversity in ornithogenic soils compared to mineral soils on King George Island, Antarctica

In the Nar?bski Point area of King George Island of Antarctica, ornithogenic soils form on land under Chinstrap and Gentoo Penguin rookeries. The purpose of this study was to compare the bacterial community compositions in the gradient of contamination by penguin feces; mineral soil with no contamination, and soils with medium or high contamination. The discrimination between mineral soils and ornithogenic soils by characterization of physicochemical properties and bacterial communities was notable. Physicochemical analyses of soil properties showed enrichment of carbon and nitrogen in ornithogenic soils. Firmicutes were present abundantly in active ornithogenic soils, Bacteroidetes and Proteobacteria in a formerly active one, and several diverse phyla such as Proteobacteria, Actinobacteria, and Acidobacteria in mineral soils. Some predominant species belonging to the Firmicutes and Gammaproteobacteria may play an important role for the mineralization of nutrients in ornithogenic soils. Results of this study indicate that dominant species may play an important role in mineralization of nutrients in these ecosystems.     

Diversity Dynamics of Marine Bacteria Studied by Immunofluorescent Staining on Membrane Filters

Of 34 strains of marine bacteria isolated on a general seawater medium, 5 were selected for detailed studies of their population dynamics in the plankton. The isolates were characterized as Aeromonas sp., Chromobacterium cf. lividum, Vibrio sp., and two Pseudomonas spp. Specific antibodies were produced by immunization of rabbits, and bacterial cells were stained on black Uni-Pore membrane filters by an indirect immunofluorescent staining procedure. The method proved to be very specific and practical for use in a large-scale field sampling program. Growth of all five isolates was stimulated by high values for net primary production, chlorophyll a, and dissolved organic carbon. Calculation of a diversity index based on specific and total counts is proposed as a way of characterizing the dynamics of organotrophic bacterial populations in the sea.     

Development of New Multilocus Variable Number of Tandem Repeat Analysis (MLVA) for Listeria innocua and Its Application in a Food Processing Plant

Listeria innocua is an important hygiene indicator bacterium in food industries because it behaves similar to Listeria monocytogenes, which is pathogenic to humans. PFGE is often used to characterize bacterial strains and to track contamination source. However, because PFGE is an expensive, complicated, time-consuming protocol, and poses difficulty in data sharing, development of a new typing method is necessary. MLVA is a technique that identifies bacterial strains on the basis of the number of tandem repeats present in the genome varies depending on the strains. MLVA has gained attention due to its high reproducibility and ease of data sharing. In this study, we developed a MLVA protocol to assess L. innocua and evaluated it by tracking the contamination source of L. innocua in an actual food manufacturing factory by typing the bacterial strains isolated from the factory. Three VNTR regions of the L. innocua genome were chosen for use in the MLVA. The number of repeat units in each VNTR region was calculated based on the results of PCR product analysis using capillary electrophoresis (CE). The calculated number of repetitions was compared with the results of the gene sequence analysis to demonstrate the accuracy of the CE repeat number analysis. The developed technique was evaluated using 60 L. innocua strains isolated from a food factory. These 60 strains were classified into 11 patterns using MLVA. Many of the strains were classified into ST-6, revealing that this MLVA strain type can contaminate each manufacturing process in the factory. The MLVA protocol developed in this study for L. innocua allowed rapid and easy analysis through the use of CE. This technique was found to be very useful in hygiene control in factories because it allowed us to track contamination sources and provided information regarding whether the bacteria were present in the factories.     

Tracking Microbial Contamination in Retail Environments Using Fluorescent Powder - A Retail Delicatessen Environment Example

Cross contamination of foodborne pathogens in the retail environment is a significant public health issue contributing to an increased risk for foodborne illness. Ready-to-eat (RTE) processed foods such as deli meats, cheese, and in some cases fresh produce, have been involved in foodborne disease outbreaks due to contamination with pathogens such as Listeria monocytogenes. With respect to L. monocytogenes, deli slicers are often the main source of cross contamination. The goal of this study was to use a fluorescent compound to simulate bacterial contamination and track this contamination in a retail setting. A mock deli kitchen was designed to simulate the retail environment. Deli meat was inoculated with the fluorescent compound and volunteers were recruited to complete a set of tasks similar to those expected of a food retail employee. The volunteers were instructed to slice, package, and store the meat in a deli refrigerator. The potential cross contamination was tracked in the mock retail environment by swabbing specific areas and measuring the optical density of the swabbed area with a spectrophotometer. The results indicated that the refrigerator (i.e. deli case) grip and various areas on the slicer had the highest risk for cross contamination. The results of this study may be used to develop more focused training material for retail employees. In addition, similar methodologies could also be used to track microbial contamination in food production environments (e.g. small farms), hospitals, nursing homes, cruise ships, and hotels.     

Mercury in Scalp Hair Near the Mid-Atlantic Ridge (MAR) in Relation to High Fish Consumption

The aim of this study was to evaluate the potential risk of mercury contamination near the Mid-Atlantic Ridge relating total mercury (THg) concentrations in the human scalp hair (n?=?110) and high fish consumption levels. THg was quantified in human scalp hair, and volunteers were questioned about age, gender, and smoking habits being subsequently grouped in categories based on the individual average intake of fish meals per week. THg concentrations ([THg]) in hair samples ranged from 0.05 to 2.24 μg g^?1, and significant differences were found according to age (p?<?0.05) and also among volunteers presenting different fish consumption rates (p?<?0.001) being the highest [THg] observed on the adult population and also on volunteers that indicated consuming five or more meals of fish per week. Results indicate a pattern of increased mercury accumulation with increasing fish consumption. Despite mercury availability and a potential mercury intake of up to seven times, the WHO provisional tolerable weekly intake of mercury value, in consequence of high fish consumption, mercury concentrations in scalp hair are comparatively low regarding recommended levels by WHO.     

Mercury concentrations in hair exposed in vitro to mercury vapor

Hair is often used as an index of environmental and industrial exposure to different metals. The interpretation of metal levels in hair is difficult because of the risk of external contamination. The aim of this study was to define the degree of external contamination of hair exposed in vitro to mercury vapor. Specimens of hair were exposed to concentration: 0.026, 0.21, and 2.7 mg Hg/m³ for 2–28 d. Mercury levels in hair increased during 28 d of exposure 2, 3 and 13, times, respectively, when compared to initial values. Mercury levels in hair exposed to the first and second (but not third) concentration of mercury vapor attained a steady state on the 21st d of exposure. The contamination of hair with mercury could not be removed by washing with water, solvent, and detergent. Hair may be used as an index of internal uptake of mercury provided that it was not externally exposed to mercury vapor. In cases of occupational exposure to mercury vapor, hair could become a useful tool for monitoring exposures.     

An improved method for detecting foreign DNA in plasmids of Escherichia coli.

A new procedure has been developed for lysing bacterial colonies on nitrocellulose filters and immobilizing the released DNA on the filters. The procedure involves the use of lysozyme and Triton X-100. When used in conjunction with in situ hybridization, this method has proven effective in detecting DNA recombinants, while eliminating the problems of false positives and variation between duplicate filters that are seen with other methods.     

Diagnostics method for the rapid quantitative detection and identification of low-level contamination of high-purity water with pathogenic bacteria

High-purity water (HPW) can be contaminated with pathogenic microorganisms, which may result in human infection. Current culture-based techniques for the detection of microorganisms from HPW can be slow and laborious. The aim of this study was to develop a rapid method for the quantitative detection and identification of pathogenic bacteria causing low-level contamination of HPW. A novel internally controlled multiplex real-time PCR diagnostics assay was designed and optimized to specifically detect and identify Pseudomonas aeruginosa and the Burkholderia genus. Sterile HPW, spiked with a bacterial load ranging from 10 to 10³ cfu/100 ml, was filtered and the bacterial cells were removed from the filters by sonication. Total genomic DNA was then purified from these bacteria and subjected to testing with the developed novel multiplex real-time PCR diagnostics assay. The specific P. aeruginosa and Burkholderia genus assays have an analytical sensitivity of 3.5 genome equivalents (GE) and 3.7 GE, respectively. This analysis demonstrated that it was possible to detect a spiked bacterial load of 1.06 × 10² cfu/100 ml for P. aeruginosa and 2.66 × 10² cfu/100 ml for B. cepacia from a 200-ml filtered HPW sample. The rapid diagnostics method described can reliably detect, identify, and quantify low-level contamination of HPW with P. aeruginosa and the Burkholderia genus in <4 h. We propose that this rapid diagnostics method could be applied to the pharmaceutical and clinical sectors to assure the safety and quality of HPW, medical devices, and patient-care equipment.     

Isolation, Characterization, and Identification of Bacterial Contaminants in Semifinal Gelatin Extracts

Bacterial contamination of gelatin is of great concern. Indeed, this animal colloid has many industrial applications, mainly in food and pharmaceutical products. In a previous study (E. De Clerck and P. De Vos, Syst. Appl. Microbiol. 25:611-618), contamination of a gelatin production process with a variety of gram-positive and gram-negative bacteria was demonstrated. In this study, bacterial contamination of semifinal gelatin extracts from several production plants was examined. Since these extracts are subjected to harsh conditions during production and a final ultrahigh-temperature treatment, the bacterial load at this stage is expected to be greatly reduced. In total, 1,129 isolates were obtained from a total of 73 gelatin batches originating from six different production plants. Each of these batches was suspected of having bacterial contamination based on quality control testing at the production plant from which it originated. For characterization and identification of the 1,129 bacterial isolates, repetitive-element PCR was used to obtain manageable groups. Representative strains were identified by means of 16S rRNA genesequencing, species-specific gyrB PCR, and gyrA and rpoB sequencing and were tested for gelatinase activity. The majority of isolates belonged to members of Bacillus or related endospore-forming genera. Representative strains were identified as Bacillus cereus, Bacillus coagulans, Bacillus fumarioli, Bacillus amyloliquefaciens, Bacillus licheniformis, Bacillus pumilus, Bacillus sonorensis, Bacillus subtilis, Bacillus gelatini, Bacillus thermoamylovorans, Anoxybacillus contaminans, Anoxybacillus flavithermus, Brevibacillus agri, Brevibacillus borstelensis, and Geobacillus stearothermophilus. The majority of these species include strains exhibiting gelatinase activity. Moreover, some of these species have known pathogenic properties. These findings are of great concern with regard to the safety and quality of gelatin and its applications.