Wound infections after surgery in a modern operating suite: clinical, bacteriological and epidemiological findings

A prospective study of 2983 operations in general and orthopaedic surgery during 3 years performed in four operating theatres in a modern operating suite was carried out in order to evaluate the importance of airborne infection. Weekly nose-and-throat samples were taken from the surgical staff and pre-operative samples were taken from the nose, throat, skin and perineum of the patients. The air contamination was followed by using settle plates, which showed low mean counts of total bacteria of between 9 and 15 c.f.u./m²/min, with mean counts of Staph. aureus of between 0·03 and 0·06 c.f.u./m²/min. No correlation was found between the total number of bacteria and the incidence of post-operative infections or between the amount of Staph. aureus in the air and post-operative Staph. aureus infections. It was concluded that further increases in ventilation could, at best, only marginally affect the incidence of post-operative infection.     

Bacterial contamination in a modern operating suite. 3. Importance of floor contamination as a source of airborne bacteria

The redispersal factor for bacteria-carrying particles from a contaminated floor was determined after mopping, blowing and walking activity. Walking gave the highest redispersal factor, 3.5 X 10(-3) m-1, which was three times higher than for blowing and 17 times higher than for mopping. The mean die-away rate for the bacteria-carrying particles used was 1.9/h without ventilation and 14.3/h with ventilation. It was calculated that in the operating rooms less than 15% of the bacteria found in the air were redispersed floor bacteria.     

Bacterial contamination in a modern operating suite. 3. Importance of floor contamination as a source of airborne bacteria.

The redispersal factor for bacteria-carrying particles from a contaminated floor was determined after mopping, blowing and walking activity. Walking gave the highest redispersal factor, 3.5 X 10(-3) m-1, which was three times higher than for blowing and 17 times higher than for mopping. The mean die-away rate for the bacteria-carrying particles used was 1.9/h without ventilation and 14.3/h with ventilation. It was calculated that in the operating rooms less than 15% of the bacteria found in the air were redispersed floor bacteria.     

西安市部分手术室尘埃粒子数与浮游菌监测报告

目的了解西安市市属医院洁净手术室环境质量状况,为保障手术室洁净质量提供参考。方法采用现场采样与检测方法,对西安市 15所市属医院的洁净手术室进行空气洁净度检测与分析。结果共监测51间手术间。其中二级医院24间,三级医院27间;Ⅰ级手术室26间,Ⅲ级手术室25间。Ⅰ、Ⅲ级洁净手术室≥0.5 μm/粒径合格率分别为76.92%、80.00%,≥5 μm/粒径合格率分别为73.08%、88.00%。Ⅰ级和Ⅲ级洁净手术室尘埃粒子数合格率分别为61.54%和80.00%,经检验差异无统计意义（χ2=2.092,P＞0.05）。三级医院洁净手术室尘埃粒子数合格率为85.19%,高于二级医院的58.33%（χ2=4.600,P<0.05）。二、三级医院手术区浮游菌检测合格率分别为87.50%、92.59%,周边区合格率分别为95.83%、92.59%,二、三级医院手术区及周边区浮游菌检测合格率比较差异均无统计学意义（均P＞0.05）。结论西安市市属医院洁净手术室尘埃粒子数和浮游菌均存在不同程度超标,尤其是二级医院应加强手术室环境质量管理。     

Airborne contamination in an operating suite: report of a five-year survey

Airborne contamination in an operating suite was studied with a slit sampler, settle plates and a light-scattering particle counter. In conventional operating rooms there was a significant difference between the empty rooms and rooms in use; the mean total bacterial count by a slit sampler changed from 1.1 in empty to 42.5 c.f.u./m3 in use (39 times increase), the settle plates count changed from 1.5 to 17.4 c.f.u./m2/min (12 times increase), and the mean total particle count changed from 56.9 to 546.7/l (10 times increase) respectively. The increase was caused mainly by persons present in the room. Another difference was found between zones in the operating suite; the bacterial count in the clean area doubled in the semi-clean area and further doubled in the dirty area in slit sampler count as well as settle plates count, and particle count in the clean area increased by 14 times in the semi-clean and dirty areas. This difference resulted from the different quality of the ventilating system. Air cleanliness of operating rooms in use by persons present in the room dropped to a level between the clean and the semi-clean area in spite of the high quality of the ventilating system. Bacterial species identified were mostly coagulase negative staphylococci and micrococci. Our study indicates that reduction of airborne contamination in an operating suite is accomplished by the combination of an efficient ventilating system and the restriction of the number of persons present in the room.     

Airborne contamination in an operating suite: report of a five-year survey.

Airborne contamination in an operating suite was studied with a slit sampler, settle plates and a light-scattering particle counter. In conventional operating rooms there was a significant difference between the empty rooms and rooms in use; the mean total bacterial count by a slit sampler changed from 1.1 in empty to 42.5 c.f.u./m3 in use (39 times increase), the settle plates count changed from 1.5 to 17.4 c.f.u./m2/min (12 times increase), and the mean total particle count changed from 56.9 to 546.7/l (10 times increase) respectively. The increase was caused mainly by persons present in the room. Another difference was found between zones in the operating suite; the bacterial count in the clean area doubled in the semi-clean area and further doubled in the dirty area in slit sampler count as well as settle plates count, and particle count in the clean area increased by 14 times in the semi-clean and dirty areas. This difference resulted from the different quality of the ventilating system. Air cleanliness of operating rooms in use by persons present in the room dropped to a level between the clean and the semi-clean area in spite of the high quality of the ventilating system. Bacterial species identified were mostly coagulase negative staphylococci and micrococci. Our study indicates that reduction of airborne contamination in an operating suite is accomplished by the combination of an efficient ventilating system and the restriction of the number of persons present in the room.     

Evaluation and determinants of airborne bacterial concentrations in school classrooms

A survey of 39 elementary schools was undertaken to determine indoor air concentrations of bioaerosols within a coastal, temperate climatic zone in British Columbia, Canada. This article reports the results for airborne bacteria. Determinants of exposure were grouped into environmental (outdoor temperature, relative humidity, season, weather), ventilation and comfort parameter (indoor relative humidity, temperature, indoor CO2 concentration, indoor fungal concentration), and occupancy (number of occupants, activity levels, occupancy patterns) variables. Regression modeling was used to evaluate the association between these factors and measured concentrations of indoor mesophilic bacteria. Naturally ventilated rooms (47% of the total rooms surveyed) had higher bacterial counts than mechanically ventilated rooms (geometric mean 325 vs. 166 CFU/m3, respectively, p < 0.001). In univariate analyses, bacterial counts were negatively correlated with supply and exhaust flow rates, air exchange rates, and the percentage of the day that occupants spent quietly sitting at their desks. Analysis of bacterial groups indicated various sources of the bacterial aerosol, with micrococci and staphylococci closely associated with occupancy variables, Bacillus with site and occupancy, and coryneform bacteria with site variables only. Approximately 60% of the variance in the outcome measurement of total bacteria was accountedfor by indoor CO2, lower air exchange rate, the age of the building, signs of current or old moisture stains, room volume, indoor relative humidity, and occupant activity level in a multiple linear regression model, with ventilation factors accounting for 40% of the variance.     

The airborne excretion by pigs of swine vesicular disease virus

The air of loose-boxes holding pigs affected with swine vesicular disease was sampled for virus. In the multistage impinger virus to a titre of 10^2·6 TCID 50 was associated with particles greater than 6 μm., 10^1·6 with particles 3-6 μm. and 10^1·4 or less with particles less than 3 μm. In the noses of workers in contact with the pigs for periods not less than 5 min., virus to a titre of 10^2·4 TCID 50 was found. Virus was recovered from the air for 2-3 days during the disease and maximum titre in pigs infected by injection or by contact occurred on the second to third day after generalization of the lesions. The amounts of virus were about 160-fold less than those recovered from pigs affected with foot-and-mouth disease, and the quantity and time of excretion suggest that the source of swine vesicular disease virus in the aerosol may be from the lesions and skin rather than from the respiratory tract.     

Evaluation of airborne operating room bacteria with a Biap slit sampler.

A Biap slit sampler and a Casella Mk 2 slit sampler were studied in an orthopaedic operating theatre. Both showed similar bacterial counts in the range of 74-640 c.f.u. (colony forming units)/m3. During operations, as average count of 220 c.f.u./m3 (range 52-482) was obtained. A close relationship was demonstrated between the number of airborne bacteria and the frequency of traffic through doors.     

Transfer of Staphylococcus aureus via nurses' uniforms

The contamination of gowns and uniforms worn in a burns unit and the transfer of patient''s staphylococci by means of nurses'' uniforms was investigated. The median values of staphylococci found on gowns and jackets worn during a routine nursing procedure were 3·0 × 10⁴ and 1·4 × 10³ respectively. From the results of model nursing experiments it appeared as if the fraction of staphylococci transferred from a patient''s room to the air in a receiving room was 4 to 10 times less when protective gowns were worn than when no gowns were worn. The corresponding transfer directly to the model `patient'' was 100 times less. The protection afforded by a gown seemed mainly to be due to protection against contamination of the uniform worn underneath when nursing a burned patient. The discrepancy between the transfer of an airborne particle tracer and Staph. aureus-carrying particles earlier found in the ward could be explained by the dispersal of Staph. aureus from nurses'' clothing.     

Evaluation of a real-time method for monitoring volatile organic compounds in indoor air in a Japanese university

Objective

Real time monitoring of total volatile organic compounds (TVOC) in rooms of Japanese university buildings was carried out to understand the temporal changes in actual indoor air quality.

Methods

The TVOC concentrations in seven different rooms, consisting of a lecture room, a seminar room, three laboratories, a computer room and a library, were monitored continuously for 24 h via a personal VOC monitor equipped with a semiconductor gas sensor. An active sampling-thermal desorption method using stainless steel tubes packed with Tenax-TA was also carried out simultaneously to verify the usability of the monitor.

Results

The TVOC concentrations measured by the personal VOC monitor were closely correlated with those measured by the active sampling method. The TVOC concentration in all rooms was generally low during the day and increased during the night. This concentration change corresponded to the ventilation cycle in the building. During the day, the TVOC concentration was generally lower than the provisional target criterion (advisable value) of indoor air quality in Japan (400 μg/m³). During the night, however, it exceeded this criterion in several rooms, especially during the summer season.

Conclusion

The real-time monitor using a semiconductor gas sensor can provide useful data on changes in the TVOC concentration in indoor air with high sensitivity.     

The importance of airborne bacterial contamination of wounds

An investigation was made into the sources of bacterial contamination of hip and knee joint replacement operations carried out in either a conventionally-ventilated or a laminar-flow operating room. It was demonstrated that the bacterial count in the air during the operations was 413/m³ in the conventionally-ventilated and 4/m³ in the laminar-flow room (a 97-fold reduction) and the average number of bacteria washed out after surgery was 105 and three, respectively (a 35-fold reduction); these facts suggest that 98 per cent of bacteria in the patients' wounds, after surgery in the conventionally-ventilated operating room, came directly or indirectly from the air. It was also ascertained that the minority of bacteria in the wound fell directly from the air (perhaps 30 per cent); the remainder presumably fell on to other surfaces and were transferred indirectly to the wound by other routes. Analysis of the relationship between the number of bacteria washed from the wound at the end of operation to both the number of bacteria in the air of the operating room and those on the patient's skin at the wound site, clearly showed that the most important and consistent route of contamination was airborne. However, on occasions when patients had exceptionally high skin carriage of bacteria, gross wound contamination occurred.     

Short term exposure to airborne microbial agents during farm work: exposure-response relations with eye and respiratory symptoms

OBJECTIVES—Exposure to high levels of non-infectious microbial agents is recognised as a cause of respiratory disease in working populations, but except for endotoxins, little is known about exposure-response relations. As these effects do not depend on viability, exposure to non-viable microbial agents is important. Various methods not based on microbial cultures were explored to study the complex microbial exposure of farmers and associations with acute symptoms during work.
METHODS—Airborne exposure was measured when farmers carried out specific tasks. Fungal spores, bacteria, endotoxins, β(1→3)-glucans, fungal antigens specific for Penicillium and Aspergillus species, and mites were measured by methods not based on microbial cultures. Also silica, inorganic and organic dust, ammonia, hydrogen sulphide, and nitrogen dioxide were measured. Respiratory, and nose and eye symptoms experienced during measurements were recorded by a short questionnaire. Both univariate and multivariate statistical analyses were applied to assess the relations between exposure and acute symptoms.
RESULTS—106 Farmers and their spouses participated in this study. Prevalences of work related symptoms were: wheezing 3%; chest tightness 7%; cough 14%; eye symptoms 18%; and nose symptoms 22%. Prevalence ratios for nose and eye symptoms were 4-8 after exposure to 20-500×10³ fungal spores/m³ and higher, and a prevalence ratio for cough was 4 after exposure to 500-17 000×10³ fungal spores/m³. Nose symptoms were also associated with exposure to silica with prevalence ratios of 4-6 after exposure to 0.015-0.075 mg /m³ and higher.
CONCLUSIONS—Farmers had a high occurrence of symptoms of the nose and eyes as well as cough during work. These symptoms were associated in a dose dependent manner with exposure to fungal spores. Nose symptoms were also associated with exposure to silica.


Keywords: bioaerosols; exposure; fungal spores; work related symptoms; respiratory effects; exposure-response     

Commuters’ Exposure to Particulate Matter Air Pollution Is Affected by Mode of Transport,Fuel Type,and Route

Background

Commuters are exposed to high concentrations of air pollutants, but little quantitative information is currently available on differences in exposure between different modes of transport, routes, and fuel types.

Objectives

The aim of our study was to assess differences in commuters’ exposure to traffic-related air pollution related to transport mode, route, and fuel type.

Methods

We measured particle number counts (PNCs) and concentrations of PM_2.5 (particulate matter ≤ 2.5 μm in aerodynamic diameter), PM₁₀, and soot between June 2007 and June 2008 on 47 weekdays, from 0800 to 1000 hours, in diesel and electric buses, gasoline- and diesel-fueled cars, and along two bicycle routes with different traffic intensities in Arnhem, the Netherlands. In addition, each-day measurements were taken at an urban background location.

Results

We found that median PNC exposures were highest in diesel buses (38,500 particles/cm³) and for cyclists along the high-traffic intensity route (46,600 particles/cm³) and lowest in electric buses (29,200 particles/cm³). Median PM₁₀ exposure was highest from diesel buses (47 μg/m³) and lowest along the high- and low-traffic bicycle routes (39 and 37 μg/m³). The median soot exposure was highest in gasoline-fueled cars (9.0 × 10⁻⁵/m), diesel cars (7.9 × 10⁻⁵/m), and diesel buses (7.4 × 10⁻⁵/m) and lowest along the low-traffic bicycle route (4.9 × 10⁻⁵/m). Because the minute ventilation (volume of air per minute) of cyclists, which we estimated from measured heart rates, was twice the minute ventilation of car and bus passengers, we calculated that the inhaled air pollution doses were highest for cyclists. With the exception of PM₁₀, we found that inhaled air pollution doses were lowest for electric bus passengers.

Conclusions

Commuters’ rush hour exposures were significantly influenced by mode of transport, route, and fuel type.     

Assessment of airborne asbestos fiber concentrations in urban area of Tehran, Iran

Air quality in ambient outdoor air has seldom been evaluated in Iran. Accordingly, we evaluated airborne asbestos fiber concentrations in the urban environment of Tehran, Iran between January 2006 and March 2007. The airborne fiber concentrations of 80 air samples collected from 40 different sites in five areas of Tehran were analyzed by energy-dispersive X-ray analysis in combination with phase-contrast optical microscopy (PCM) and scanning electron microscopy (SEM). The geometric means of the airborne asbestos fiber concentrations were 3.4 × 10⁻³ PCM f/ml (0.1 SEM f/ml) and 3.3 × 10⁻³ PCM f/ml (0.20 SEM f/ml) according to areas and seasons, respectively. There were significant differences in the asbestos fiber concentrations between the areas and seasons (p = 0.02; p = 0.04), respectively. In the areas, the average concentration was 3.4 × 10 ⁻³ PCM f/ml (0.1 SEM f/ml), which is considerably higher than those reported for the levels of asbestos in outdoor air in the USA and the urban environment of the Europe. The SEM analyses revealed that the fibrous particles consisted, approximately, of chrysotile (60%), tremolite (10%), anthophyllite (10%), and non-asbestos fibers (20%). We conclude that the high volume of traffic, industrial consumption of asbestos, and geographical and climate conditions are responsible for the high airborne asbestos levels in non-occupational environments in Tehran. Thus, it is to be expected that inhabitants of Tehran will suffer negative health effects due to exposure to asbestos airborne fibers.     

Effects of airborne particulate matter on respiratory morbidity in asthmatic children

Background

The effects of airborne particulate matter (PM) are a major human health concern. In this panel study, we evaluated the acute effects of exposure to PM on peak expiratory flow (PEF) and wheezing in children.

Methods

Daily PEF and wheezing were examined in 19 asthmatic children who were hospitalized in a suburban city in Japan for approximately 5 months. The concentrations of PM less than 2.5 µm in diameter (PM_2.5) were monitored at a monitoring station proximal to the hospital. Moreover, PM_2.5 concentrations inside and outside the hospital were measured using the dust monitor with a laser diode (PM_2.5(LD)). The changes in PEF and wheezing associated with PM concentration were analyzed.

Results

The changes in PEF in the morning and evening were significantly associated with increases in the average concentration of indoor PM_2.5(LD) 24 h prior to measurement (-2.86 L/min [95%CI: -4.12, -1.61] and -3.59 L/min [95%CI: -4.99, -2.20] respectively, for 10-µg/m³ increases). The change in PEF was also significantly associated with outdoor PM_2.5(LD) concentrations, but the changes were smaller than those observed for indoor PM_2.5(LD). Changes in PEF and concentration of stationary-site PM_2.5 were not associated. The prevalence of wheezing in the morning and evening were also significantly associated with indoor PM_2.5(LD) concentrations (odds ratios = 1.014 [95%CI: 1.006, 1.023] and 1.025 [95%CI: 1.013, 1.038] respectively, for 10-µg/m³ increases). Wheezing in the evening was significantly associated with outdoor PM_2.5(LD) concentration. The effects of indoor and outdoor PM_2.5(LD) remained significant even after adjusting for ambient nitrogen dioxide concentrations.

Conclusion

Indoor and outdoor PM_2.5(LD) concentrations were associated with PEF and wheezing among asthmatic children. Indoor PM_2.5(LD) had a more marked effect than outdoor PM_2.5(LD) or stationary-site PM_2.5.Key words: Particulate Matter, Asthma, Peak Expiratory Flow Rate, Respiratory Sounds     

Wound ventilation with ultraclean air for prevention of direct airborne contamination during surgery.

BACKGROUND AND OBJECTIVE: Despite the novelties in operating room ventilation, airborne bacteria remain an important source of surgical wound contamination. An ultraclean airflow from the ceiling downward may convey airborne particles from the surgical team into the wound, thus increasing the risk of infection. Therefore, similar ventilation from the wound upward should be considered. We investigated the effect of wound ventilation on the concentration of airborne particles in a wound model during simulated surgery. DESIGN: Randomized experimental study simulating surgery with a wound cavity model. SETTING: An operating room of a university hospital ventilated with ultraclean air directed downward. INTERVENTIONS: Particles 5 microm and larger were counted with and without a 5-cm deep cavity and with and without the insufflation of ultraclean air. RESULTS: With the surgeon standing upright, no airborne particles could be detected in the wound model. In contrast, during simulated operations, the median number of particles per 0.1 cu ft reached 18 (25th and 75th percentiles, 12 and 22.25) in the model with a cavity and 15.5 (25th and 75th percentiles, 14 and 21.5) without. With a cavity, wound ventilation markedly reduced the median number of particles to 1 (range, 0 to 1.25; P < .001). CONCLUSIONS: To protect a surgical wound against direct airborne contamination, air should be directed away from the wound rather than toward it. This study provides supportive evidence to earlier studies that operating room ventilation with ultraclean air is imperfect during surgical activity and that wound ventilation may be a simple complement. Further clinical trials are needed.     

How Improvements in Monitoring and Safety Practices Lowered Airborne Formaldehyde Concentrations at An Italian University Hospital: a Summary of 20 Years of Experience

The last two decades have been crucial for the assessment of airborne formaldehyde (FA) exposure in healthcare environments due to changes in limits and reference values, definition of carcinogenicity, and new monitoring methods. The aim of this study was to analyse twenty years (1999–2019) of experience in automatic, continuous airborne FA monitoring in the Pathology Laboratory and operating rooms at the Careggi University Hospital, Florence, Italy. These 20 years saw gradual improvements in FA monitoring of exposed employees considered at maximum risk, including improvements in analytical methods of detection and sampling strategies, which came with changes in procedures and workflow operations. In 2019, after the adoption of safe practices, including a closed-circuit system using pre-loaded containers and a vacuum sealing, 94 % of the total measurements (FA concentrations) were lower than 16 μg/m³, and only 6 % ranged from 21 to 75 μg/m³. In the studied work units, the ratio between area and personal readings ranged from 0.9 to 1.0, both for long and short-term sampling. Personal sampling was simplified with a new workstation, which integrated different monitoring systems into an innovative ergonomic armchair equipped with personal sampling devices. Area monitoring was also improved with a real-time, continuous photoacoustic instrument. Over these 20 years, FA exposure significantly dropped, which coincided with optimised histology workflow and implementation of safety practices. For high-throughput screening and cost savings we propose an innovative ergonomic armchair station which allows remote continuous monitoring.     

Studies on aircraft disinsection at ��blocks away��

With a view to expediting as much as possible the disinsection of aircraft required under the International Sanitary Convention for Aerial Navigation, experiments were performed under operating conditions on the disinsection of passenger cabins after the closing of the aircraft doors following embarkation but before take-off (designated ”blocks away” disinsection) with single-use, disposable aerosol dispensers. A formulation containing 1.6% by weight pyrethrum extract (25% pyrethrins) and 3% DDT at a dosage of 10 g per 1000 cubic feet (35 g/100 m³) gave satisfactory control of non-resistant mosquitos and created no passenger reaction. A formulation containing 3.40% pyrethrum extract (20% pyrethrins) and 1.17% DDT at a dosage of 14-19 g per 1000 cubic feet (48-64 g/100 m³) was biologically effective for both resistant and non-resistant mosquitos but was markedly irritant to some passengers. The authors suggest lines along which further research might be conducted.     

Modelling the transmission of airborne infections in enclosed spaces

The Wells-Riley equation for modelling airborne infection in indoor environments is incorporated into an SEIR epidemic model with a short incubation period to simulate the transmission dynamics of airborne infectious diseases in ventilated rooms. The model enables the effect of environmental factors such as the ventilation rate and the room occupancy to be examined, and allows the long-term impact of infection control measures to be assessed. A theoretical parametric study is carried out to demonstrate how changes to both the physical environment and infection control procedures may potentially limit the spread of short-incubation-period airborne infections in indoor environments such as hospitals.