Comparison of Microbial Contamination Levels Among Hospital Operating Rooms and Industrial Clean Rooms

Microbial contamination in industrial clean rooms was compared quantitatively and qualitatively with that of hospital operating rooms. The number of aerobic mesophilic microorganisms which accumulated on stainless-steel strips exposed for periods up to 21 weeks to the intramural air of four operating rooms was at least 1 log higher than the accumulation on strips exposed in four clean rooms, and was essentially the same as that found in two factory areas. Volumetric air samplings showed that there were significantly higher numbers of airborne viable particles per cubic foot of air in operating rooms than in industrial clean rooms. In contrast to clean rooms, where most of the airborne contaminants were those associated with human hair, skin, and respiratory tract, the hospital operating rooms showed a very high level of microorganisms associated with dust and soil.     

Microbiological Evaluation of Protected Environments During Patient Occupancy

Microbiological monitoring has been conducted in two life island (LI) units and two laminar airflow (LAF) rooms while they were occupied by patients undergoing cancer chemotherapy. There were only 5 organisms per 1,000 ft(3) of air sampled in LAF rooms, 31 organisms in LI units, and over 3,000 organisms in regular hospital rooms. None of the floor samples obtained from hospital rooms was sterile, compared to over 70% in LAF rooms. The rate of deposition of organisms onto settling plates was one organism per 4.5 hr in LAF rooms compared to one organism per 0.08 hr in hospital rooms. Potential pathogens were isolated much more frequently from environmental samples obtained from hospital rooms than from LI units or LAF rooms. Two sites of persistent contamination arose in the LAF rooms: the vinyl tile flooring and the water supply system. Over half of the potential pathogens cultured from the protected environment units were cultured initially from the patients who occupied the units.     

Contamination of a hospital environment byClostridium difficile

Clostridium difficile was recovered from a variety of environmental sites in three hospital rooms occupied by a patient who had colitis due to this organism.C. difficile was detected for 40 days after the patient was moved from one of these rooms. These findings suggest that the contaminated hospital environment may be a clinically significant reservoir forC. difficile and that this organism may be a nosocomial pathogen. Isolation of patients and adequate decontamination of rooms may be needed to minimize risk to other patients.     

Ozone decontamination of bioclean rooms.

To establish a convenient method for decontaminating bioclean rooms, the effect of ozone at 80 mg/m3 for 72 h was compared with formaldehyde vaporization at an initial concentration of 150 mg/m3 with a gradual decrease to 20 mg/m3 during 72 h. Ozone was found to be inferior to formaldehyde in activity. When the bioclean room was decontaminated twice with ozone, the mean colony count per 10 cm2 was decreased to about the same level as when formaldehyde was used. Ozone had a strong caustic effect upon rubber materials. Despite these disadvantages, ozone decontamination was demonstrated to be superior to formaldehyde vaporization because of convenience, insignificant inhalation of the disinfectant by the hospital staff, and very rapid expulsion of the gas after ventilation. Because the disadvantages of ozone can be easily controlled, this study suggests that ozone decontamination is a promising method for maintaining bioclean rooms.     

Optimal timing of insecticide fogging to minimize dengue cases: modeling dengue transmission among various seasonalities and transmission intensities

Background

Dengue infection is endemic in many regions throughout the world. While insecticide fogging targeting the vector mosquito Aedes aegypti is a major control measure against dengue epidemics, the impact of this method remains controversial. A previous mathematical simulation study indicated that insecticide fogging minimized cases when conducted soon after peak disease prevalence, although the impact was minimal, possibly because seasonality and population immunity were not considered. Periodic outbreak patterns are also highly influenced by seasonal climatic conditions. Thus, these factors are important considerations when assessing the effect of vector control against dengue. We used mathematical simulations to identify the appropriate timing of insecticide fogging, considering seasonal change of vector populations, and to evaluate its impact on reducing dengue cases with various levels of transmission intensity.

Methodology/Principal Findings

We created the Susceptible-Exposed-Infectious-Recovered (SEIR) model of dengue virus transmission. Mosquito lifespan was assumed to change seasonally and the optimal timing of insecticide fogging to minimize dengue incidence under various lengths of the wet season was investigated. We also assessed whether insecticide fogging was equally effective at higher and lower endemic levels by running simulations over a 500-year period with various transmission intensities to produce an endemic state. In contrast to the previous study, the optimal application of insecticide fogging was between the onset of the wet season and the prevalence peak. Although it has less impact in areas that have higher endemicity and longer wet seasons, insecticide fogging can prevent a considerable number of dengue cases if applied at the optimal time.

Conclusions/Significance

The optimal timing of insecticide fogging and its impact on reducing dengue cases were greatly influenced by seasonality and the level of transmission intensity. We suggest that these factors should be considered when planning a control strategy against dengue vectors.     

Laminar Airflow Protection In Bone Marrow Transplantation

A laminar airflow room was used to provide a low-pathogen environment for a child with lymphopenic immune deficiency transplanted with paternal bone marrow. Comparison of flora from the patient, personnel, and the environment indicated that no colonization with exogenous organisms occurred in the patient during the 45-day period of study. The number of organisms recovered from the laminar airflow room was exceedingly small. Conventional hospital isolation rooms contained more bacteria and fungi than the laminar airflow room, even when strict aseptic procedures were followed in the former. Patients with lymphopenic immune deficiency and agranulocytosis admitted to conventional isolation rooms were colonized with exogenous organisms within 1 week. Each developed infection with these strains, and one patient died. Laminar airflow isolation seems at present the best means to prevent exogenous infection during hospitalization of patients with lymphopenic and other severe immune-deficiency diseases and may be essential when bone marrow transplantation is performed to treat their immunological defect.     

Assessment of the diversity and abundance of terrestrial mangrove arthropods in southern New South Wales,Australia

Abstract The diversity and abundance of arboreal and flying arthropods, in three mangrove patches along the south coast of New South Wales, Australia, was investigated to determine the degree of spatial variability in the assemblages among patches. Intercept traps and restricted canopy fogging were used to sample the communities at Minnamurra, Bonnievale and Kurnell. Twelve orders of arthropods were detected, incorporating 252 morphospecies. Abundance, species richness and species composition were very similar across all patches, the variation being much smaller than expected. These findings suggest that the composition of the arboreal and flying fauna associated with mangrove patches are very similar among patches, but preliminary results also showed that species composition could be highly variable within a patch. Variation between the trapping methods was large, as expected . Intercept trapping and restricted canopy fogging techniques were found to sample different suites of species and therefore complement each other well in sampling programs. Cumulative species curves differed between time periods but generally were flatter for intercept traps than for restricted canopy fogging. Results suggested, for a given level of effort, intercept traps caught a more representative sample of the species composition available to them.     

Effect of Exposure Temperature on Over-All Efficiency of Autoradiographs and on Fogging of Emulsion

Systematic investigations of the influence of various temperatures of exposure on the autoradiographic efficiency and on the rate of fogging of Kodak AR 10 stripping film were carried out. The oxygen content and humidity of the exposed autoradiographs as well as the time of exposure were constant. Exposure of autoradiographs or storage of film at room temperature caused an increase of overall autoradiographic efficiency by approximately 40%, but although the rate of film fogging was also increased, it did not exceed the safe values of background. Both autoradiographic efficiency and rate of fogging were not altered significantly when a temperature of 4 C or -18 C for exposure was used. Therefore, room temperature of exposure is recommended for ordinary autoradiography. For a special autoradiographic technic when low temperature of exposure has to be used, the temperature -18 C may be safely applied without significant impairment of autoradiographic efficiency.     

Characterization of micro-organisms isolated from dairy industry after cleaning and fogging disinfection with alkyl amine and peracetic acid

AIMS: To characterize micro-organisms isolated from Norwegian dairy production plants after cleaning and fogging disinfection with alkyl amine/peracetic acid and to indicate reasons for survival. METHODS AND RESULTS: Microbial samples were collected from five dairy plants after cleaning and fogging disinfection. Isolates from two of these production plants, which used fogging with alkylamino acetate (plant A), and peracetic acid (plant B), were chosen for further characterization. The sequence of the 16S ribosomal DNA, fatty acid analysis and biochemical characteristics were used to identify isolates. Three isolates identified as Rhodococcus erythropolis, Methylobacterium rhodesianum and Rhodotorula mucilaginosa were isolated from plant A and one Sphingomonas sp. and two M. extorquens from plant B. Different patterns of resistance to seven disinfectants in a bactericidal suspension test and variable degree of attachment to stainless steel were found. The strains with higher disinfectant resistance showed lower degree of attachment than susceptible strains. CONCLUSIONS: The study identifies and characterizes micro-organisms present after cleaning and fogging disinfection. Both surface attachment and resistance were shown as possible reasons for the presence of the isolates after cleaning and disinfection. SIGNIFICANCE AND IMPACT OF THE STUDY: These results contribute to the awareness of disinfectant resistance as well as attachment as mechanisms of survival in dairy industry. It also strengthens the argument of frequent alternation of disinfectants in the food processing industry to avoid the establishment of resistant house strains.     

Routes of the transmission of Pseudomonas aeruginosa infection in resuscitation and intensive therapy departments

To find out if the transfer of P. aeruginosa infection by droplet route is possible in resuscitation and intensive care units, the bacteriological study of air samples taken in different rooms of resuscitation units (altogether 234 air samples) was carried out with the subsequent identification and typing of isolated P. aeruginosa strains. In most cases (70.5%) the microbial contamination of the air in the main rooms of resuscitation units was found not to exceed 500 microbial cells per cu. m, and no P. aeruginosa strains were isolated. The identification and typing of six P. aeruginosa strains isolated from the air of an isolation ward for patients with infectious complications made it possible to find out intraspecific differences of these microorganisms, as all of them belonged to strains of different sero- and pyocinotypes. Thus, the results of these investigations indicate that the droplet route of the transfer of P. aeruginosa hospital infection is not characteristic of resuscitation and intensive care units, as no P. aeruginosa strains are isolated from the main rooms of such units; likewise, no circulation of this microorganism was observed in the air of an isolation ward for patients with infectious complications.     

Impact of permethrin-treated bednets on malaria transmission by the Anopheles gambiae complex in The Gambia

Malaria vector mosquitoes belonging to the Anopheles gambiae complex were studied in four hamlets in The Gambia. All inhabitants were given bednets treated either with a placebo (milk) in two hamlets or with the pyrethroid insecticide permethrin (500 mg/m2) in two other hamlets. Malaria transmission occurred mainly during a few weeks of the rainy season, in September and October 1987. The indoor resting densities of mosquitoes in permethrin-treated hamlets were reduced, and we estimated over 90% reduction in biting on man by An. gambiae Giles sensu stricto in these hamlets. No mosquitoes were found under permethrin-treated bednets compared with eighty-one recovered from placebo-treated bednets. Mosquitoes exited more readily from rooms where permethrin-treated bednets were used than from rooms with placebo-treated nets. The annual mean probability that a child would receive an infective bite was estimated to be 0.09 in hamlets with insecticide-treated bednets, compared with 1.9 where placebo-treated bednets were used. Permethrin-treated bednets are therefore recommended as a means of effectively reducing the risk of exposure to malaria transmission, particularly in areas of low seasonal transmission.     

Validation of AKACID plus as a room disinfectant in the hospital setting

AKACID Plus, a novel polymeric guanidine with broad antimicrobial activity against multiantibiotic-resistant bacterial strains, was used in the present study as a room disinfectant. Disinfection of closed rooms experimentally contaminated with antibiotic-susceptible and multiresistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, and Escherichia coli was performed using AKACID Plus at concentrations of 0.1, 0.25, and 0.5% for 100 min. Bacterial suspensions were distributed on plastic and stainless steel plates and placed in a test room. Recovery of the test microorganisms was determined before nebulizing, 60 and 100 min after initiation, and 4 h after the end of room disinfection by a simple swab-rinse technique. The swab-rinse method demonstrated a dose- and time-dependent effectiveness of AKACID Plus in eradicating S. aureus, E. coli, and P. aeruginosa on plastic and stainless steel plates. Nebulized 0.5% AKACID Plus was successful in eliminating all hospital pathogens within 340 min. After the use of 0.25% AKACID Plus, MRSA was still detectable on microbial carrier plates. The test concentration of 0.1% AKACID Plus achieved a significant reduction of S. aureus and P. aeruginosa on plastic and stainless steel plates but was sufficient to eradicate only E. coli. These results suggest that nebulized AKACID Plus at a concentration of 0.5% is a potent substance for eradication of pathogenic organisms in the hospital setting.     

Arthropods in epiphytes: a diversity component that is not effectively sampled by canopy fogging

Insecticide fogging is often used to document arthropod species richnessin forest canopies, but this technique may not effectively sample invertebratesthat are concealed within a variety of microhabitats. We quantified the effectsof fogging on invertebrates in canopy epiphyte mats of a Costa Rican cloudforest by extracting arthropods from 18 paired pre- and post-fogging samples.Mean abundance and morphospecies richness of living arthropods were respectivelyreduced by 33 and 30% in epiphyte material after fogging, but most organismssurvived the treatment. Relative abundances of major taxa were unaffected byfogging. Herbivores were less abundant after fogging than other trophic groups,and the median body length of non-mite arthropods present in epiphytes wassignificantly smaller after fogging. Examination of seven post-fogging samplesshowed that many arthropods killed by insecticide remained trapped within theepiphyte material. These results provide the first quantitative assessment of aspecific component of arboreal arthropod biodiversity that is missed by thefogging technique.     

Arthropod biodiversity loss and the transformation of a tropical agro-ecosystem

The coffee (Coffea arabica) agro-ecosystem in the Central Valley of Costa Rica was formerly characterized by a high vegetational diversity. This complex system has been undergoing a major transformation to capital-intensive monocultural plantations where all shade trees are eliminated. In this study we examined the pattern of arthropod biodiversity loss associated with this transformation. Canopy arthropods were sampled in three coffee farms: a traditional plantation with many species of shade trees, a moderately shaded plantation with only Erythrina poeppigeana and coffee, and a coffee monoculture. An insecticidal fogging technique was used to sample both canopy and coffee arthropods. Data are presented on three major taxonomic groups: Coleoptera, non-formicid Hymenoptera, and Formicidae. Data demonstrate that the transformation of the coffee agro-ecosystem results in a significant loss of biological diversity of both canopy arthropods as well as arthropods living in coffee bushes. Percentage of species overlap was very small for all comparisons. Furthermore, species' richness on a per tree basis was found to be within the same order of magnitude as that reported for trees in tropical forests. If results presented here are generalizable, this means that conservation efforts to preserve biological diversity should also include traditional agro-ecosystems as conservation units.     

The relationship between rubella hemagglutination inhibition antibody (HIA) and rubella induced in vitro lymphocyte tritiated thymidine incorporation

The parameters of lymphocyte, rubella virus interaction were studied by means of tritiated thymidine incorporation and compared with the rubella HIA level. Stimulation of lymphocyte DNA synthesis was found to depend on antigen concentration and to be independent of the presence of viable virus. When compared to HIA titer, lymphocyte transformation was found to be detectable in the absence of antibody. It is suggested that lymphocyte transformation is a sensitive method to detect both prior exposure and cellular immune reactivity to rubella virus.     

Metagenomic Human Repiratory Air in a Hospital Environment

Hospital-acquired infection (HAI) or nosocomial infection is an issue that frequent hospital environment. We believe conventional regulated Petri dish method is insufficient to evaluate HAI. To address this problem, metagenomic sequencing was applied to screen airborne microbes in four rooms of Beijing Hospital. With air-in amount of sampler being setup to one person’s respiration quantity, metagenomic sequencing identified huge numbers of species in the rooms which had already qualified widely accepted petridish exposing standard, imposing urgency for new technology. Meanwhile,the comparative culture only got small portion of recovered species and remain blind for even cultivable pathogens reminded us the limitations of old technologies. To the best of our knowledge, the method demonstrated in this study could be broadly applied in hospital indoor environment for various monitoring activities as well as HAI study. It is also potential as a transmissible pathogen real-time modelling system worldwide.     

Airborne bacteria and antibiotic resistance genes in hospital rooms

The microbial biodiversity of bioaerosols in recently occupied hospital rooms was assessed in a pulmonology unit. Environmental samples and isolates were also screened for antibiotics resistance genes. Biofilms from sink drains were also studied to evaluate whether sink drains constitute a potential source of bioaerosols in this environment and a reservoir for opportunistic bacteria and antibiotic resistance genes. Stenotrophomonas maltophilia was by far the most frequently isolated microorganisms from the biofilm, followed by Enterobacter cloacae. Airborne bacterial concentration ranged from 14 to 74 CFU m⁻³ and fungi ranged from 50 to 600 CFU m⁻³. Biofilm bacteria were outnumbered in aerosols by microorganisms affiliated with human skin flora. Nonetheless, they were recovered from air samples in low concentrations. Erythromycin resistance genes were detected in all air samples collected from hospital rooms, and tetracycline resistance genes were detected sporadically. Antibiotic resistance genes were found in a single drain suggesting that genes present in DNA extracts from air samples were not aerosolized from sink drains, but rather from an unknown source. Results obtained in this study suggest that bacteria from sink drains were not aerosolized in significant concentration. They still remain a concern because of the risk of aerial transmission associated with their presence.     

Germ monitoring of patients, staff and environment in reverse isolation

To estimate the efficiency of germ-poor for patients who underwent BMT or ABMT in reverse isolation we investigated the staff, patients and the environment of the BMT unit bacteriologically and mycologically between 1/85 to 3/87. On patient's body surface gram-negative germs were not estimated but coagulase negative staphylococci persisted. Only in few cases aerobic spores were detectable, seldom enterococci, corynebacterium and fungi. Staff members had a distinct higher grade of contamination inside the BMT-unit but outside of isolation rooms. We found sporadically staphylococcus aureus and germs of the mouth cavity on hands and fore head. Although gram negative rods were seldom detected in environmental studies, humid regions of the ward remain to be problematic zones.     

Biological Evaluation of Carpeting

Studies of microbial contamination were carried out on a carpet strip (acrilan) installed in a laboratory corridor and on two carpet strips (acrilan and wool) installed in two rooms in a pediatric hospital. A sampling procedure of randomly removing 8-mm plugs from the carpets was used for subsequent enumeration and identification of contaminating microorganisms. Microbial counts increased with time, reached a "plateau" at about 4 weeks, and appeared to be related to the amount of activity present in the carpeted area. Vacuuming of carpets showed only a slight reduction in the number of recoverable microorganisms. Qualitative studies on a strip of acrilan carpet installed in a hospital room indicated that Staphylococcus epidermidis and gram-positive nonsporeforming rods were the predominating microorganisms. Coagulase-positive S. aureus organisms were isolated during every sampling period, and gram-negative rods were also regularly isolated. Most nitrate-reducing gram-negative rods belonged to the Enterobacter and Escherichia groups. Survival studies conducted on carpet strips after hospital installation showed relatively constant levels of contamination for about 6 weeks, followed by a gradual reduction in numbers; coagulase-positive S. aureus were found for 35 days, whereas the proportions of most organisms remained relatively constant with time.     

Open ward management of acute alcoholism; experience with a pilot program

Sixty acutely alcoholic patients were treated in unsegregated rooms of two to twelve beds in a general hospital to determine the feasibility of open ward care. Personnel caring for them were first educated in the nature of alcoholism, the aberrations it produces and treatment with tranquilizing drugs. Fears and objections were overcome. Violent or unpredictable patients were excluded from the test, but those with alcoholic hallucinations or delirium suspectible to control were admitted. Preliminary physical examination was done to find out whether there was coincidental disease. In three patients, one with subarachnoid hemorrhage, one with severe anemia and one with pneumonia and shock, this examination followed by prompt treatment was probably life-saving. Tranquilizers, fluids and vitamins were given routinely, by mouth as soon as possible. Alcoholic patients were found to be no more unmanageable than others. If it were generally accepted that acutely alcoholic patients, diagnosed as such, could be admitted to open ward care in general hospitals, candor in diagnosis would be encouraged thereby, coincident disease probably would be promptly recognized if present, and long-term treatment for the alcoholic addiction could be begun early.