Amoebae and humidifier fever

One hundred and nineteen sera from workers at four different work sites exposed to different contaminated humidifiers were examined by the immunofluorescent antibody (IFA) technique for antibodies to the amoebae Acanthamoeba polyphaga and Naegleria gruberi. Twenty-five of the sera were from workers with humidifier fever (HF) and six from workers with work related asthma (WRA) shown to be due to the contaminated humidifiers. A positive IFA test was found to correlate precipitin reaction to humidifier antigen, but did not correlate with smoking habit, work related symptoms (detected by standard questionnaire) or with HF or WRA. Amoebae were identified in all humidifiers studied.     

Airborne endotoxins and humidifier disease

The presence of humidifier disease in a printing factory was investigated with particular emphasis on airborne endotoxins. The water in the humidifier was contaminated with Pseudomonas. The amount of airborne endotoxin when the humidifier was operating was 0.13-0.39 microgram/m3. Twenty of the fifty workers investigated reported typical symptoms of fever, chills, and chest tightness when the humidifiers were operating. Symptoms were more frequent among non-smokers. The estimated inhaled dose of endotoxin was found to be sufficient to cause the observed symptoms. The determination of airborne endotoxins in future episodes of humidifier disease is recommended.     

An in-hospital evaluation of the sonic mist ultrasonic room humidifier.

It is generally recognized that nebulizers can be a source of nosocomial infection. 'Cold mist' room humidifiers are a particular problem because they are difficult to sterilize. We evaluated a new device, the Sonic Mist ultrasonic room humidifier, to determine how quickly it became contaminated during continuous use by a population of cystic fibrosis patients. In addition, the study was designed to test the effectiveness of placing a bacterial filter on the air inlet of the humidifier. We found that the entire humidifier could withstand repeated gas sterilization. Data obtained from 18 humidifiers involving cystic fibrosis patients indicate that the earliest humidifier contamination occurred after 5 days of continuous use. Although all patients had large numbers of gram-negative bacilli as predominant sputum flora, only 7 episodes of contamination were found during 34 humidifier-use periods. Three units equipped with filters became contaminated (5-7 days) and four unfiltered units became contaminated (6-11 days), indicating that the use of an inlet filter made no apparent difference. The organisms recovered from contaminated units were not found as sputum flora and would not generally be considered of clinical significance in cystic fibrosis sputum cultures. Probable sources of the organisms were room dust and hand contamination. A further test of the inlet filter was performed by exposing filtered and unfiltered units to mist from an intentionally contaminated humidifier. Again, the contamination rate was low and the filter apparently made no difference. These results indicate that the Sonic Mist humidifier may be appropriate for hospital use if adequate sterilization and contamination-monitoring practices are followed.     

A comparison of the rate of bacterial contamination for prefilled disposable and reusable oxygen humidifiers

BACKGROUND: Prefilled disposable oxygen humidifiers are considered to prevent nosocomial pneumonia in hospital wards. However, their usefulness in intensive care units (ICUs) has not yet been established. In this study, we evaluated and compared contamination in prefilled disposable oxygen humidifiers and that in reusable oxygen humidifiers. METHODS: Six oxygen outlets in the ICU were used. Prefilled disposable oxygen humidifiers and reusable oxygen humidifiers were attached to each wall-mounted oxygen outlet using a 2-way connector. Nonsterile nasal cannulae and tubes were connected to the humidifiers through which 5 L/min of oxygen was delivered continuously. Water samples (5 mL) from each humidifier were collected on the first day and every 7 days thereafter for a period of 56 days. Each water sample was incubated aerobically at 35 degrees C for 48 hours and observed daily for bacterial growth. RESULTS: Bacterial growth was observed only once in one sample from each humidifier type. Gram-positive cocci, 40 colony-forming units in the disposable oxygen humidifier and 10 colony-forming units in the reusable oxygen humidifier, were detected. Dust was observed from the 35th day onward only in the reusable oxygen humidifier. CONCLUSION: In the ICU, bacterial contamination does not occur in oxygen humidifiers even after 56 days of continuous use. However, dust does accumulate in the reusable oxygen humidifier after 35 days of continuous use.     

消毒后备用湿化瓶的干燥方法及存放时间探讨

氧气湿化瓶是输氧装置的一部分,使用率高,是一个极易带菌的感染源,其造成的医院内感染已被临床所证实[1],但其保存方法在护理操作中尚未规范化[2]。根据《医院感染管理规范》要求,氧气湿化瓶及其管道,用毕应终末消毒,干燥保存[3]。由于氧气湿化瓶及其管道是塑料制品,不能采用高     

消毒后备用湿化瓶的干燥方法及存放时间探讨

目的探讨消毒后备用湿化瓶干燥方法及存放时间，为其妥善保存提供依据，减少因湿化瓶保存不当而污染造成的医院内感染。方法对消毒后的84个氧气湿化瓶随机分为A组和B组各42个，分别采用自然晾干和氧气吹干2种不同的干燥方法，在不同月份连续7d进行细菌监测，并对结果进行分析。结果采用氧气吹干法的湿化瓶比自然晾干法的湿化瓶可多保存1d。结论消毒后备用湿化瓶的保存时间，应根据季节不同，干燥方法不同，确定不同的有效保存时间。     

Multipatient use of prefilled disposable oxygen humidifiers for up to 30 days: patient safety and cost analysis

BACKGROUND: Prefilled disposable oxygen humidification units have been shown to decrease the likelihood of contamination when compared to reusable oxygen humidification units. However, prefilled disposable humidifiers are expensive when used for single patients, especially in areas of high turnover, and it is not known whether these units need to be routinely changed before they are empty. The number of patients safely using a prefilled disposable humidifier has not been documented in previously reported work. Are patients at risk of nosocomial infections due to cross-contamination when prefilled disposable oxygen humidifiers are applied to multi-patient use? What are the cost benefits of multiple patient use of prefilled disposable oxygen humidifiers? When local practice or physician preference dictates the use of humidification for low-flow oxygen, these questions need to be answered. METHODS & MATERIALS: Data were collected over two time periods to address changes due to seasonal variations and include area of use, number of patients, and quantitative cultures for aerobic microorganisms (including Legionella). Each disposable humidifier was monitored for a period of 1 month or until only 1 inch of water remained. Costs of using reusable humidifiers and prefilled humidifiers and therapist/nurse time to initiate therapy with both units were compared. During this period, 60 reusable humidifiers were also cultured for aerobic microorganisms and Legionella. RESULTS: We report results on 1,311 of the 1,315 disposable prefilled oxygen humidifiers used. We saw no significant growth in any of the prefilled disposable humidifiers for periods of up to 30 days, with > 100 humidifiers having been used by > 20 patients. CONCLUSIONS: Our results show that prefilled disposable oxygen humidifiers can be used without cross-contamination, on multiple patients, for a period of 1 month. The use of prefilled humidifiers in this way represents a substantial cost saving when compared to reusable humidifiers.     

Bacteriologic evaluation of the Servo 150 hygroscopic condenser-humidifier

The Servo 150 hygroscopic condenser-humidifier was evaluated during use to determine if the inner foam core became contaminated and if a bacteria-laden aerosol was produced during the inspiratory cycle of the patient's mechanical ventilator. Cultures from the core and of inspired gas were obtained from seven patients with known culture-positive sputum, after 4, 8, 12 and 24 h of humidifier use. In each case, the inner foam core was grossly contaminated after 4 h of use and colony counts increased during the 24-h testing period. The bacteria recovered were the same as those cultured from sputum. Despite the core's heavy bacterial growth, a bacteria-laden aerosol occurred in only 43% of the samples obtained during humidifier use. The Servo humidifier does not appear to increase the risk of airway exposure to airborne bacteria during mechanical ventilation.     

Budgerigar fancier's lung. The persistence of budgerigar precipitins and the recovery of lung function after cessation of avian exposure

Forty-eight budgerigar fanciers have been studied and twenty-five (52%) of these lost their serum budgerigar precipitins after cessation of avian exposure. Twenty (80%) subjects lost their precipitins within 2 years. The lung function was assessed serially in seventeen patients with allergic alveolitis and correlated with the persistence of their serum precipitins. There was no difference in the lung function at presentation or in the incidence of complete recovery between the ten subjects, whose precipitins persisted for longer than 2 years, and the seven individuals in whom the precipitins had disappeared within this time. These observations suggest that budgerigar precipitins do not have a major role to play in the continuing pathogenesis of allergic alveolitis.     

Studies on the capacity of some polysaccharides to elicit antibody formation in man

Purified levan is antigenic in man and subcutaneous injection of 1 mg. leads to the production of precipitins and skin sensitivity. Apple amylopectin, maize glycogen, and synthetic polyglucose did not stimulate antibody production in small numbers of individuals injected. Quantitative precipitin studies carried out with several levan preparations employing human antilevan show variations in immunochemical behavior indicating structural differences among levans. Evidence that precipitins formed in response to levan injection are antilevan antibodies was obtained by analysis of specific precipitates formed in the region of antibody excess for ketosugar. Injection of levan giving rise to production of antilevan failed in one individual to give a non-specific anamnestic rise in either antidextran or antiblood group A precipitins. Laminarin, a neutral polysaccharide, was found to give precipitation with normal human sera.     

ON ALBUMINOLYSINS AND THEIR RELATION TO PRECIPITIN REACTIONS

The writer believes that the experiments above recorded have demonstrated the following points: 1. As has been previously shown by other workers, complement is fixed by the precipitate formed in the reaction between unformed proteid and its homologous antiserum, and it is the precipitate only which fixes, the supernatant fluid being devoid of fixing power except to a slight degree in tubes very rich in antigen. This latter fixation is probably due to a redissolving of the precipitin-precipitinogen complex which, as Gay has shown, does not lose its fixing power on resolution. The fixation of complement by mixtures in which antigen is so slight in amount that no precipitate is formed may be explained by analogy with colloidal reactions in which combination of colloids takes place without precipitation unless definite quantitative relations are maintained. 2. In contrast to the results above described, precipitating mixtures of bacterial antigen and antiserum show complement fixation both by the precipitate and by the supernatant fluid. 3. The complement fixation by the supernatant fluid of such bacterial precipitin reactions, with the precipitate removed, is, in the presence of washed bacteria, equal to that exerted by the same amount of the original serum. The complement fixation of the precipitates, here, as in serum-antiserum tests, is proportionate to the bulk of the precipitate. 4. The precipitin body is not removed from a bacterial antiserum by treatment with washed whole bacteria, whereas the cell sensitizer or amboceptor is removed by such treatment. The writer believes that the work recorded above justifies Gengou''s conclusion that an albuminolytic sensitizer is formed in response to immunization with unformed proteids. This sensitizer, or amboceptor, is, however, distinct and independent of the sensitizer that reacts specifically with either bacterial or other cells. It would appear that immunization with unformed proteids calls forth only the formation of these albuminolysins, while immunization with cells, in our case the typhoid bacillus, calls forth both the cytolytic and the albuminolytic sensitizers. The albuminolytic sensitizers are not carried down mechanically with the precipitates in the precipitin reactions. We see no reason for not considering them identical with the precipitins themselves, bodies which combine with the dissolved antigens and, as in other colloidal reactions, lead to precipitation when definite quantitative relations are observed. The undiminished precipitating value of a bacterial antiserum after considerable amounts of bacterial amboceptor have been absorbed out of it, would point against the identification of agglutinins with precipitins. However, this question must be subjected to further study. It is thus clear that only the cytolytic sensitizer can enter into combination with the washed bacterial cell, while it is probable that both cytolytic and albuminolytic sensitizer may combine with the dissolved ingredients of a bacterial filtrate. Whether or not they combine with the same constituent of such an antigen cannot be decided by our experiments.     

ARDS after double extrinsic exposure hypersensitivity pneumonitis

Hypersensitivity pneumonitis or extrinsic allergic alveolitis is a lung disease due to T cell and macrophage activation with IgA, IgG or IgE immunocomplex tissue lesions following extrinsic exposure to organic or inorganic agents. We report a case of hypersensitivity pneumonitis (pigeon protein sensitized) with a second nosocomial exposure to Aspergillus fumigatus proteins from a contaminated oxygen water humidifier: the second extrinsic exposure induced significant acute respiratory failure with ARDS. A pre-existing COPD syndrome requiring prolonged oxygen therapy (7 days) involved lung disease with delayed clinical diagnosis and therapy. Microbiological and mycological analysis of oxygen water humidifiers should be considered, especially for hypersensitivity pneumonitis patients, when a new inexplicable clinical impairment occurs. Received: 17 November 1998 Final revision received: 23 March 1999 Accepted: 30 April 1999     

Is neonatal inspired gas humidity accurately controlled by humidifier temperature?

OBJECTIVE: To investigate: a) the relationship between humidifier temperature and inspired gas humidity and b) the effect of insulating the inspiratory tube on "rainout" (condensate). DESIGN: Observational study. SETTING: Regional neonatal unit in a university hospital. PATIENTS: Forty-eight infants receiving assisted ventilation, of whom 31 infants were nursed in incubators and 17 under radiant heaters. MEASUREMENTS AND MAIN RESULTS: Despite always maintaining humidifier temperature greater than 34.7 degrees C, inspired gas humidity decreased below the American National Standards Institution minimum of 30 mg H2O/L on 35 of 479 occasions. At a humidifier temperature of 36 degrees C, inspired gas humidity varied between 17 and 43 mg H2O/L. In incubators set at a temperature of 34.1 +/- 1.3 (SD) degrees C, inspired gas humidity was linearly related to humidifier temperature, but with wide scatter (p less than .001, r2 = .28). In cooler incubators set at 32.9 +/- 1.8 degrees C, inspired gas humidity varied inversely with humidifier temperature. This variation was attributed to condensate due to inspired gas cooling within the incubator. Insulation of the inspiratory tubing reduced condensate by only 15%. CONCLUSIONS: Inspired gas humidity cannot be predicted reliably from humidifier temperature. Accurate control will require a new generation of humidifiers that measure inspired gas humidity.     

Care of the ventilator circuit and its relation to ventilator-associated pneumonia

Ventilator circuits should not be changed routinely for infection control purposes. The maximum duration of time that circuits can be used safely is unknown. Evidence is lacking related to ventilator-associated pneumonia (VAP) and issues of heated versus unheated circuits, type of heated humidifier, method for filling the humidifier, and technique for clearing condensate from the ventilator circuit. Although the available evidence suggests a lower VAP rate with passive humidification than with active humidification, other issues related to the use of passive humidifiers (resistance, dead space volume, airway occlusion risk) preclude a recommendation for the general use of passive humidifiers. Passive humidifiers do not need to be changed daily for reasons on infection control or technical performance. They can be safely used for at least 48 hours, and with some patient populations some devices may be able to be used for periods of up to 1 week. The use of closed suction catheters should be considered part of VAP prevention strategy, and they do not need to be changed daily for infection control purposes. The maximum duration of time that closed suction catheters can be used safely is unknown. Clinicians caring for mechanically ventilated patients should be aware of risk factors for VAP (eg, nebulizer therapy, manual ventilation, and patient transport).     

PRECIPITIN RESPONSE IN THE BLOOD OF RABBITS FOLLOWING SUBARACHNOID INJECTIONS OF HORSE SERUM

1. Rabbits which have received a single dose of normal horse serum in the subarachnoid space produce precipitins in the blood in greater abundance, of higher titer, and persisting longer than those in control rabbits which have received a similar injection intravenously. 2. Repeated subarachnoid injections of normal horse serum in rabbits induce precipitins in the blood early. These may appear in high titer as soon as 1 week after the initial injection, whereas in rabbits similarly treated intravenously no precipitins are found at this time. They may appear a few days afterward and reach a high titer. 3. No anaphylactic manifestations occurred in rabbits treated repeatedly with subarachnoid injections of normal horse serum when the precipitin content of the blood was high. 4. Anaphylactins, as determined by passive transfer of anaphylaxis, were demonstrated in sera with high precipitin content. 5. These experiments may explain clinical evidences of anaphylaxis, observed when an initial intravenous injection of horse serum followed a series of intraspinal injections of such serum.     

Utilisation des filtres échangeurs de chaleur et d’humidité au cours de la ventilation mécanique des patients de réanimation

Adequate heating and humidifying of inspired gases is required for long-term mechanical ventilation of intensive care unit (ICU) patients. This process can be achieved by either a heated humidifier or by more recent disposable devices called heat and moisture exchangers (HME). The choice to use one method instead of the other depends on both technical and economic considerations. HMEs are more often used nowadays because they are simple to use and cost-effective. Their performances are for several models comparable to those of a heated humidifier. The vast majority of ICU patients can be ventilated with an HME. They are usually changed after 24 h of use. It has recently been shown that some HMEs can be changed only every 48 h and that at least one HME can be changed only once a week in some patients. Using HMEs instead of heated humidifiers has no clear impact on the rate of nosocomial pneumonia but considerably reduces the cost of mechanical ventilation and the number of septic procedures, thus improving quality of care.     

THE RELATION OF ANTIBODY TO THE RATE OF DISAPPEARANCE OF CIRCULATING ANTIGEN

1. In rabbits previously immunized to horse serum the rate of disappearance of horse serum after reinjection is somewhat more rapid than in control animals not previously immunized. But when the average duration of the persistence of antigen in ten previously immunized rabbits is compared with the average duration of persistence in ten normal controls, the difference is not impressive. This holds true for animals previously immunized by repeated injections but having no free circulating antibody, as well as for animals having a high titer of antibody at the time of reinjection. The same animal may dispose of circulating antigen as rapidly at a time when the blood contains no precipitin as when there is a high titer of circulating precipitin. 2. The intravenous injection of large amounts of potent antihorse rabbit serum immediately after an injection of horse serum does not materially accelerate the rate of disappearance of the horse serum from the circulation. While the number of days that circulating antigen was demonstrable in two experiments of this type was less than the average of controls the duration of persistence was within the limits of variation of normal controls. 3. Under the condition of the experiments intravascular union of antigen and antibody is an unimportant factor in the mechanism for disposal of antigen. By exclusion it therefore seems probable that the rate of disappearance of antigen is largely dependent upon cell avidity for the antigen. 4. Rabbits show a wide range of individual variation in the rapidity with which foreign serum is appropriated by the tissue cells, and in their ability to form precipitins. There does not appear to be any close relation between the amount of precipitin set free in the circulation and the rate of disappearance of precipitinogen. 5. The type of interrelation between precipitin and precipitinogen—demonstrable not infrequently in patients with serum disease—in which the precipitinogen diminishes rapidly when the precipitin rises to the crest of its curve is sometimes reproduced in rabbits. The type of curve which has been observed in patients with little or no serum disease in which the precipitinogen persists steadily in the circulation for many weeks and little or no antibody is formed, has not been observed in the present series of rabbits.     

INSUSCEPTIBILITY TO SENSITIZATION AND ANAPHYLACTIC SHOCK

1. Attempts to produce anaphylactic shock in white rats by second intravenous or subdural injections of horse serum have failed. 2. It was impossible to demonstrate either by skin reactions or by the uterine reaction that white rats can be sensitized to horse serum. 3. It was not possible to sensitize guinea pigs passively with the serum of white rats presumably immunized to horse serum. 4. In spite of the fact that the white rat could not be made anaphylactic to horse serum, the tissues of the animal reacted with the horse serum to form precipitins in fair concentration and the antigen disappeared from the circulation soon after the precipitins reached their greatest concentration in the blood. 5. These experiments would indicate that in the white rat anaphylaxis and precipitin formation are independent and represent different types of immunological processes.     

STUDIES IN SENSITIZATION TO SKIN : I. THE PRODUCTION OF ANTIBODIES TO SKIN BY MEANS OF THE SYNERGISTIC ACTION OF HOMOLOGOUS SKIN ANTIGEN AND STAPHYLOCOCCUS TOXIN

1. Techniques for the preparation of skin antigen suitable for intramuscular injection in rabbits, and of skin antigens (autolysate) for serological experiments are described. 2. A method was evolved which produced a soluble skin antigen (autolysate) suitable for performing precipitin tests. 3. Injection of the rabbit skin antigen and of staphylococcus toxin in rabbits resulted in the formation of antibodies (precipitins) to homologous skin. 4. When homologous skin alone was injected into rabbits, the antibody formation was questionable, or at most, slight. 5. The injection of staphylococcus toxin alone resulted in antibody formation, this antibody being specific for the toxin and not reacting with broth. 6. By utilization of the synergistic action of staphylococcus toxin and of homologous skin antigen, it has been possible for the first time to produce specific antiskin antibodies in experimental animals.     

EQUILIBRIA IN PRECIPITIN REACTIONS : THE COEXISTENCE OF A SINGLE FREE ANTIGEN AND ITS ANTIBODY IN THE SAME SERUM.

1. In these studies several phases of the predpitm reactions were investigated by the use of purified proteins as antigens. These preparations were edestin from hemp-seed and crystalline ovalbumin from fresh eggs. The ovalbumin, isolated by the method of Hopkins and Pinkus,.was apparently as pure as is obtainable by chemical means. This albumin, however, produced moderately severe anaphylactic reactions in animals sensitized with ovoglobulin. Anaphylactic tests of the individuality of a protein cannot be any longer regarded as the criterion of the purity of the substance as an antigen. Wells and Osborne have shown that proteins of considerable chemical difference may have a common antigenic group which causes mutual anaphylactic reactions in animals sensitized to these proteins. In particular, as egg globulin is a mixture of proteins, one of which is undoubtedly egg albumin, anaphylaxis produced by injections of albumin into animals sensitized to the so called globulin offers no evidence for or against the purity of the albumin. The character of the curves shown in Text-fig. 1 confirms the assumption, based upon chemical data, that crystalline egg albumin is a single protein. 2. With edestin and crystalline egg albumin as antigens phases in the precipitin reaction were found in which these substances and their specific precipitins could be demonstrated to be coexistent but ununited in the same serum. 3. When edestin or crystalline egg albumin is injected into a rabbit immunized thereto, the antigen may be found in the circulating blood during 48 hours after its injection, while at the same time the animal maintains a high titer of free precipitin in its blood. 4. When the pure protein antigen is mixed in proper proportions with the serum of a specifically immunized rabbit and the resulting precipitate removed by centrifugation, the supernatant fluid contains both antigen and antibody. 5. The serum drawn from a rabbit during the period in which free antigen and antibody are coexistent in the circulation undergoes slow spontaneous precipitation when kept in sterile tubes in the ice box. The curve of this reaction is reproduced as Text-fig. 1. The relationships of the parabola indicate that the interaction of antigen and antibody takes place according to a definite law. When sufficient quantitative data are obtained to allow an analysis of this curve, the formulas for this reaction will undoubtedly throw light upon the chemical or physical nature of the process. 6. The protective action of the solution of egg albumin as a third colloid preventing precipitation in a reaction between human serum and its antibody was readily demonstrated. This observation and the constancy of the long prozone in precipitin test with egg albumin are in accord with the protective action of ovalbumin upon colloidal gold.