Ice Machine Research Articles

Automated endoscope reprocessing; sterile setup monitoring; air exchange rates; cleaning ice machines

Automated endoscope reprocessing; sterile setup monitoring; air exchange rates; cleaning ice machines

Maintenance of Ice Machines

Maintenance of Ice Machines

Heat and Cold: Mastering the Great Indoors by Barry Donaldson, Bernard Nagengast

1000 Book Reviews TECHNOLOGY AND CULTURE are those by W. Bernard Carlson and David Mowery. Carlson notes that in the United States business firms have historically played a key role in transforming technology from abstract design or model into social artifact. He tries to merge the insights of the social-con­ structivists’ approach to technology with economic theory, arguing that firms should not be treated as “single agents.” That is, decisions about technology within firms often reflect competing interests and ideas, and companies’ decisions about technology are the result of internal power struggles. To illustrate, he applies his interest group model to the Thompson-Houston, Edison, and Westinghouse elec­ tric companies. Building a successful technological system not only required the creation and coordination of organizational capabili­ ties; it also required the coordination (or subjugation) ofcompeting ideas and interests. David Mowrey’s essay provides both a masterful review of the his­ tory ofcorporate R & D and new insights into the broad sweep ofthis history from the establishment of the first corporate labs through the present. It explores the internal workings of research laboratories, both within firms and outside of them. And it places laboratories in the context of “national innovation systems,” to use Richard Nel­ son’s valuable phrase. Like several other contributors but more ex­ plicitly than any other, Mowrey argues that the markets-hierarchy distinction should not be drawn too sharply. Firms internalized much R&D, but before 1940 their labs were focused outward. They acted as listening posts and contact points between the firms and their competitors as well as with other parts ofthe innovation system. Mainly because of changes in public policy, those same labs became much more insular and inward focused after 1940, to the detriment of American inventiveness. It is a fitting essay to capture the import of the entire volume, for it looks from the inside out: from the busi­ ness firm that economists have taken for granted, to the larger con­ text of institutions, policies, industries, and markets that the Chandlerian brand of business history has slighted. Kenneth Lipartito Dr. Lipartito teaches in the Department of History at the University of Houston. Heat and Cold: Mastering the Great Indoors. By Barry Donaldson and Bernard Nagengast. Atlanta: American Society of Heating, Refrig­ erating and Air-Conditioning Engineers, 1994. Pp. xxvii+339; il­ lustrations, notes, index. $99.00 (hardcover). This is an illustrated history of heating and refrigeration, pre­ sented on the occasion of the hundredth anniversary of the Ameri­ can Society of Heating, Refrigerating and Air-Conditioning Engi- TECHNOLOGY AND CULTURE Book Reviews 1001 neers (ASHRAE). The society supports and organizes historical work—for instance, collecting interviews with important retired members of the society—and coauthor Bernard Nagengast was a spiritus rector of this work. The book starts in ancient times, then skips the Middle Ages to arrive fairly quickly in the 19th century (p. 30). More than two-thirds of the book is devoted to the period 1870-1930. There are good reasons for this: it was the most innovative period of refrigeration and covers the first steps of air-conditioning. Ice machines became reliable, artificial ice prevailed against natural ice, a little later the refrigerator against the icebox, and at the end of the period the control of humidity and temperature led to the rise of air-condition­ ing. Most present-dayleading companies in the field, the prime mov­ ers, and the engineering associations were founded in this period. The velocity of technological progress, as the authors note, seems to have slowed down since then (p. 309). It normally is superfluous to complain in a review about what has not been written about, but in this case the process by which the heating and cooling industry began to stagnate would have been most interesting for the historian of technology. The book is written by engineers for engineers, unlike the Fest­ schrift of the ASME Heat Transfer Division, edited by Edwin Layton and John Lienhard (1988), which had a true historical approach focusing on the science-technology relation. This book cannot de­ cide about its focus and tries everything at once. It presents many technological solutions, persons, company histories, and important building projects, but the many little...

Water as a Reservoir of Nosocomial Pathogens

Understanding the means of acquisition, sources, and reservoirs of nosocomial pathogens is crucial for developing methods to reduce the incidence of nosocomial infections. The article in this issue by Graman et all highlights the continued importance of the environment, especially water sources, as a reservoir for nosocomial pathogens. Important water reservoirs in the hospital include potable water, sinks, faucet aerators, showers, tub immersion, toilets, dialysis water, ice and ice machines, water baths, flower vases, eyewash stations, and dental-unit water stations (Table). This editorial will review water as an important reservoir of nosocomial pathogens, with a focus on methods for prevention and control.

Nosocomial Legionellosis Traced to a Contaminated Ice Machine

Nosocomial Legionellosis Traced to a Contaminated Ice Machine

Microbiological quality of ice in hospital and community

A survey was undertaken in response to a report of a clinical infection which had been related to an ice-making machine on a hospital ward. A detailed study of the ice microflora of 27 ice-making machines was performed. In a subsequent survey, ice samples ( N = 194) from establishments such as bars and hotels were examined for bacterial indicators of hygiene. Samples from hospital ice-making machines yielded low numbers of a wide range of potentially opportunistic micro-organisms, many of environmental rather than clinical origin. For ice sampled in the community, the total aerobic plate count (TAPC) at 37 °C for 95% of the samples was <500 cfu/mL, and at 22 °C 75% had < 500 cfu/mL. Examination for coliforms showed that 69% of samples contained no coliforms, but 20% contained >100 coliforms/100 mL. Escherichia coli was detected in three samples but in very low numbers. This report investigates the relevance of ice machines to the control of hospital infection, the hygiene of ice in the community, discusses the microbiological quality of ice and proposes possible guidelines.

An outbreak of cryptosporidiosis associated with a resort swimming pool.

An outbreak of cyptosporidiosis occurred in late April 1993 among resort hotel guests which was temporally associated with, but geographically distant from, a massive waterborne outbreak of cryptosporidiosis in Milwaukee, Wisconsin, that occurred in late March and early April of 1993. A case-control study was performed among groups with members who reported illness and among a systemic sample of groups who stayed at the resort hotel during the risk period. Of 120 persons interviewed, 51 (43%) met the case definition. Swimming in the resort hotel's pool was significantly associated with case status (OR = 9.8; 95% Cl 3.4, 29.7), as was consumption of ice from the hotel's ice machines (OR = 2.3; 95% Cl 1.01, 5.2). When analysis was restricted only to laboratory-confirmed cases and controls, swimming pool use was the only risk factor significantly associated with illness (OR = 13.0; 95% Cl 2.6, 88.7). Following waterborne outbreaks of cryptosporidiosis associated with water supplies, swimming pools should be considered as possible ongoing sources for transmission regionally.

Machines Are Frozen Spirit: The Scientification of Refrigeration and Brewing in the 19th Century—a Weberian Interpretation by Mikael Hård

1036 Book Reviews TECHNOLOGY AND CULTURE dent. So conservatives saw the rifle as an encouragement of an indi­ vidualism that could be dangerous in stolid, uneducated soldiers. The breechloader, with its rapid fire, was also distrusted by officers who thought that soldiers would shoot off all their ammunition prema­ turely. But in the reforming 1860s it was not considered outrageous to argue that better education for the masses would produce recruits who could be trusted to handle the new technology. In the 1904—5 Russo-Japanese War, however, the 18th-century reliance on cold steel and mass formations was still the philosophy of many officers, with dire consequences. As with the new industrial technology imposed on the Russian armories, so it was with the new tactics introduced in the 1860s—diffusion of new ideas was never as fast as anticipated. Books on this kind of offbeat subject tend to uncover all kinds of interesting details, some of which have significant implications for mainstream topics, and this valuable volume is no exception. J. N. Westwood Dr. Westwood is an Honorary Research Fellow at the Centre for Russian and East European Studies at the University of Birmingham. He is the author of Soviet Locomo­ tive Technology (London, 1982) and Russian Naval Construction 1905-1945 (London, 1994). Machines Are Frozen Spirit: The Scientification ofRefrigeration and Brew­ ing in the 19th Century—a Weberian Interpretation. By Mikael Hard. Frankfurt am Main: Campus Verlag; Boulder, Colo.: Westview Press, 1994. Pp. 275; illustrations, references, bibliography, index. DM 58.00 (paper). In this study of the transformation of German beer making, Mikael Hard embraces Max Weber’s interpretation of historical development as the appearance of a modern, occidental, rationalized world—one that promotes abstraction, quantification, systematization, control, and prediction. Hard finds that rationalization in the increasingly scientific approach to technology, and the mechanization of industry. One of the strengths of this book is Hard’s decision to chart both the push of new technical development as well as the pull of the marketplace, by focusing on the refrigeration industry and its most important customers, the large German breweries. And to plot out this story he has divided the book into three parts: refrigeration tech­ nology before 1870, the scientification of refrigeration technology 1870—93, and the rationalization of the brewing industry. In charting the intertwining rationalities of science, technology, and business, the author deploys the concept of “social carriers”—individuals, groups, companies, or institutions that have the knowledge, power, and interest to promote new technologies. Hard has chosen his categories of analysis carefully, for by focusing TECHNOLOGY AND CULTURE Book Reviews 1037 on social carriers rather than the more diffuse actor networks, he deliberately emphasizes that “power and persistence are essential fac­ tors in the promotion of technical change” (p. 70). Central to these overlapping groups is Carl von Linde, who de­ signed a vapor compression ice machine in 1870. Linde tapped the thermodynamic theory taught by Gustav Zeuner at the Swiss Poly­ technic to posit an ideal machine that would embody the reversed Carnot cycle. His use of scientific theory proved a powerful tool not only in building a more efficient machine but in establishing vapor compression as an archetype that quickly dominated the industry. Yet Linde’s contribution as an interpreter of scientific theory to engi­ neering design was soon surpassed by his role in the commercializa­ tion of his design. The Linde Company applied the same scientification to the marketplace by urging the establishment of the Munich Refrigeration Testing Station in 1888, which adjudicated rivals’ unsci­ entific claims and tutored consumers in the proper standards of per­ formance. Machines Are Frozen Spirit provides a compelling look at how the prestige of science was used for both the establishment and maintenance of an archetypal design. Here is a study that skillfully deploys historical theory and yet is written with the conviction that technological design really matters. Of special interest is the role of August Deiglmayr of the Dreher breweries and Gabriel Sedlmayr of the Spaten brewery in promoting the development of mechanical refrigeration to replace natural ice. Hard argues that the data on the infant technology provided consum­ ers with no clear economic choice. Thus...

Gram-negative bacteremia.

In the 1960s, almost all patients who developed gram-negative bacteremia during granulocytopenia died; death occurred before blood culture results were available in about 50% of cases; many patients received antibiotics that were, at best, suboptimal and frequently inactive against the invading pathogen. In the early 1970s epidemiological studies demonstrated that more than 50% of gram-negative bacteremias were caused by hospital-acquired strains which colonized along the alimentary canal and caused infection in a limited number of locations, especially the pharynx, lungs, colon, and perianum. Surveillance culture studies have demonstrated that among acquired gram-negative bacilli, Pseudomonas aeruginosa will almost invariably proceed to bacteremia if the patient becomes profoundly neutropenic, with Escherichia coli and Klebsiella pneumoniae leading to bacteremia in only a moderate number of patients and other gram-negative bacilli rarely progressing to bacteremia despite colonization. Hence, the leading causes of bacteremia in the granulocytopenic patient are E. coli, K. pneumoniae and P. aeruginosa. Further investigations demonstrated that gram-negative bacilli were acquired from hands, food, and water, thus leading to approaches to infection prevention which included careful handwashing, low-microbial-content diet, and attention to water sources, including ice machines. Another basic approach to infection prevention has been to suppress gram-negative bacilli colonizing the alimentary canal with oral nonabsorbable antibiotics or, more recently and more effectively, with agents such as the fluoroquinolones which, unlike previous regimens, do not concurrently suppress the anaerobic flora, hence maintaining colonization resistance. The third basic approach to infection prevention is to improve the host defense factors, principally by a more rapid return of circulating granulocytes with the use of colony-stimulating factors such as granulocyte/macrophage colony-stimulating factor or granulocyte colony-stimulating factor. As to therapy, the fundamental approach with presumed gram-negative bacteremia is the prompt institution of empiric antibiotic therapy when fever first develops in the setting of granulocytopenia. There is a short "window of opportunity" after which no therapy will be effective. Combinations of antibiotics such as a beta-lactam and an aminoglycoside are used for multiple reasons: to afford coverage in the event the pathogen, proves resistant to one of the agents, to afford a synergistic activity thus improving and prolonging the serum bactericidal activity, and to reduce the development of resistance. However, patients can be divided into two risk groups: those with granulocytopenia and a regenerating bone marrow and those with an aplastic marrow who will have persistent, profound (< 100 microliters) granulocytopenia.(ABSTRACT TRUNCATED AT 400 WORDS)

ECONOMIC ANALYSIS OF POST HARVEST HANDLING METHODS FOR FRESH MARKET MIXED GREENS

Several common methods of post harvest handling and pre-cooling for fresh market bunched greens (turnips, smooth and curly mustard, and collards) were evaluated. Six treatments were evaluated where greens were rehydrated and precooled using different combinations of hydrocooling, slush ice, and shoveled ice with three rehydration methods (hydrocooling, water drench, and water floating). Product temperatures were monitored and overall quality ratings were made after seven days in cold storage. Product quality after seven days was best with hydrocooling and insignificant differences in quality were recorded whether in-box ice was shoveled or slush ice. Turnips were most sensitive to degradation if precooled inadequately. Collards were the least sensitive. Economic analysis was completed using labor and ice cost differentials of selected packing and cooling methods to calculate product volume levels required to amortize relatively high costs of the hydrocooler, slush icer, and ice machine. Extremely large volume is required to fully amortize equipment acquisition costs based on labor cost savings alone. Greater cost savings per box, when comparing the cost of purchased ice to homemade ice, resulted in much lower volume requirements for full amortization. The results indicate that a producer with limited capital would benefit the most economically from acquiring an ice machine. The greatest quality benefit is gained from precooling with the hydrocooler.

Nosocomial Outbreak of Respiratory Tract Colonization withMycobacterium fortuitum: Demonstration of the Usefulness of Pulsed-Field Gel Electrophoresis in an Epidemiologic Investigation

Between August 1989 and January 1990, 16 patients on an alcoholism rehabilitation ward (ARW) developed positive sputum cultures for Mycobacterium fortuitum. During a 2-wk surveillance period, six of 43 ARW patients but none of 20 staff members had positive sputum cultures. In addition, none of 54 patients and staff on an adjacent ward sharing the same ice machine and water supply had positive cultures, and none of 92 acid-fast bacilli cultures performed on all sputum specimens from all other inpatient sources during the same 2-wk period were positive. The only exposure factor common to all cases was the use of one or both of the ward showers. Compared with 36 ARW control patients, cases were more likely to report clinical criteria for chronic bronchitis (odds ratio, 6.6; 95% confidence interval, 1.5 to 28.6; p = 0.02). Using phenotype analysis, plasmid profiles, and pulsed-field gel electrophoresis of large genomic DNA restriction enzyme fragments, the 16 case isolates were found to be identical. This strain of M. fortuitum was also cultured from a tap connected to the water line supplying the ARW showers, but not from the showers themselves. No further cases were identified after the showers were disconnected and decontaminated. To our knowledge, this is the first clinical use of pulsed-field gel electrophoresis for genetic comparison of mycobacterial strains. It demonstrates the important potential of this technique for studying the epidemiology of mycobacterial infections. Showers should be considered a possible source of nosocomial respiratory tract colonization with M. fortuitum.

Nosocomial outbreak of cryptosporidiosis in AIDS patients.

To describe a nosocomial outbreak of cryptosporidiosis during four months after June 1989. A department of infectious diseases in Copenhagen, seeing about half the patients with AIDS in Denmark. 73 HIV antibody negative subjects and 60 antibody positive subjects admitted as inpatients during the transmission period of the outbreak (20 June-14 August), of whom 18 (17 with AIDS, one with AIDS related complex), developed cryptosporidiosis. Two further HIV negative subjects (one departmental secretary, one visiting relative) developed cryptosporidiosis. Cryptosporidia in stool samples, clinical symptoms, CD4 cell count, HIV antigen concentration, chemotherapeutic treatment. The source of the outbreak was identified as ice from an ice machine in the ward, contaminated by an incontinent, psychotic patient with cryptosporidiosis picking out ice for cold drinks. The mean incubation time was at least 13 days-that is, twice that in HIV-negative patients. Of the 18 patients with AIDS who developed cryptosporidiosis, five recovered, two were symptomless carriers, three died of unrelated causes, and eight died after prolonged diarrhoea. Among the 57 exposed HIV antibody positive inpatients (excluding two patients and the index case with cryptosporidiosis diagnosed elsewhere), significantly more of those who developed symptomatic cryptosporidiosis received oral sulphonamides than those who did not (91%, 10/11 v 48%, 21/44, p less than 0.05). The clinical and epidemiological findings indicate that infection was the consequence of very small inocula. Increased sensitivity to cryptosporidiosis may be an unrecognised side effect of oral sulphonamide treatment in patients with AIDS.

Nosocomial Mycobacterium fortuitum colonization from a contaminated ice machine.

Between October 15 and November 18, 1985, 5 patients on a medical ward of the Albany VA Medical Center (Ward 8A) became colonized with Mycobacterium fortuitum. Because other patients in Ward 8A were at risk of developing disease with M. fortuitum, microbiologic surveillance to identify colonization in sputum was begun. By February 15, 1986, 30 colonized patients had been identified in this ward but none in another ward with a comparable patient population, which suggests a source unique to Ward 8A. Because water has been recognized as a source of opportunistic mycobacterial pathogens, we conducted a retrospective case-control study using a telephone survey questionnaire to examine a number of water exposures in 10 patients and 20 control subjects. Exposure to ice from the Ward 8A ice machine, but not to potable water, was associated with colonization with M. fortuitum. Large-volume water samples from a variety of sources were cultured for acid-fast bacilli. M. fortuitum was isolated only from the ice machine in Ward 8A. The ice machine was disconnected, and no additional patients became colonized. Although ice machines are infrequently implicated in nosocomial outbreaks, they represent a potential source for pathogens that survive or replicate in water.

Nosocomial Mycobacterium gordonae pseudoinfection from contaminated ice machines.

Thirty-two clinical specimens submitted to the laboratory during a 12-month period from July 1980 to June 1981 were reported to be culture-positive for Mycobacterium gordonae, an organism generally considered to be a slow-growing saprophyte with natural habitats which include soil and water. Only seven similar isolates had been recovered in the preceding 4 1/2 year period. The discordance between clinical findings and the mycobacterial cultures suggested extrinsic contamination of the specimens. Contamination in the laboratory was believed unlikely because: 1) clinical samples obtained in an aseptic manner were never contaminated; 2) various surveillance cultures of reagents and deionized water used in the laboratory were negative; and 3) substitution of deionized water with sterile water did not control the outbreak. Extensive hospital-wide cultures of water sources implicated the use of ice and ice water from contaminated ice machines as the source of this pseudoepidemic. Cleaning of the ice machines resulted in a sharp decrease in the number of M. gordonae isolates. Pseudoinfection by M. gordonae from improperly maintained ice machines has not been reported before.

Isolation of Legionella pneumophila from the cold water of hospital ice machines: implications for origin and transmission of the organism.

Although the mode of transmission of L. pneumophila is as yet unclear, the hot water distribution system has been shown to be the reservoir for Legionella within the hospital environment. In this report we identify a previously unrecognized reservoir for L. pneumophila within the hospital environment, ie, the cold water dispensers of hospital ice machines. The cold water dispensers of 14 ice machines were cultured monthly over a 1-year period. Positive cultures were obtained from 8 of 14 dispensers, yielding from 1 to 300 CFU/plate. We were able to link the positivity of these cold water sites to the incoming cold water supply by recovering L. pneumophila from the cold water storage tank, which is directly supplied by the incoming municipal water line. This was accomplished by a novel enrichment experiment designed to duplicate the conditions (temperature, sediment, stagnation, and continuous seeding) of the hot water system. Our data indicate that significant contamination of cold water outlets with L. pneumophila can occur. Although no epidemiologic link to disease was made, the fact that the primary source of a patient's drinking water is from the ice machines warrants further investigation of these water sources as possible reservoirs.

Growth of potential pathogens in denture-soaking solution of myelosuppressed cancer patients

M yelosupprcssion that results in markedly decreased numbers of circulating granulocytes and mucosal damage sustained during antineoplastic chemotherapy may predispose cancer patients to infection.‘.’ The more profound the myelosuppression, the higher the risk of infection, with a significantly higher probability of infection when granulocyte levels fall to less than 1 OO/&‘~ * Most of the infections are caused by opportunistic gram-negative bacilli, especially Pseudomonas aeruginosa, and several species of fungi.“-” Many of the organisms, which are thought to be acquired nosocomially or succeed to predominance after admission to the hospital, effect a change in the patient’s normal flora.‘~‘~ I2 As the organisms are generally not present in the pharynx of a normal population, such factors as hospital treatment modalities, serious systemic disease, and debilitation are thought to select for these pathogens.‘3-‘S Most infections in this population result from microorganisms that have colonized the patient’s alimentary canal, including the oral cavity.‘0,‘P.20 Exogenous sources of infection include food, water, shower stalls, humidifiers, ice machines, respirators, intravenous catheters, and members of the hospital staff.” In one investigation, dentures and denture-soaking containers used by myelosuppressed hospital patients were found to be contaminated heavily with pathogens, especially gram-negative bacilli. 2’ Under these conditions dentures could serve as reservoirs for pathogens in the hospital environment and as a source of infection and cross-contamination. The objective of this investigation was to determine if denture-borne pathogens would

Isolation of pathogenic microorganisms from dentures and denture-soaking containers of myelosuppressed cancer patients

I nfection is the leading cause of morbidity and mortality in patients undergoing myelosuppressive cancer chemotherapy. ‘9 2 Bone marrow supp ression and mucosal damage sustained during chemotherapy predispose these patients to infection.‘s4 Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, other gram-negative bacilli, Staphylococcus aureus, and yeasts are responsible for the majority of infections in this population. 5-* Many of these pathogens are thought to be acquired or to ascend to predominance after admission to the hospital. 6,7 At the Baltimore Cancer Research Center (BCRC) during 1971-1976, surveillance cultures of 135 patients with acute nonlymphocytic leukemia (ANLL) demonstrated that new organisms were acquired at a rate of 0.5 organism per patient per week. Many of these organisms were gram-negative bacilli and species of yeast.’ Severely myelosuppressed patients appear to be especially susceptible to infections from these organisms.2~3~5~7 Infection in these patients can be exogenously or endogenously derived.’ Defined exogenous sources include food, water, bathtubs, shower stalls, ice machines, respirators, humidifiers, intravenous catheters, urinary catheters, and members of the hospital staff.8~‘o The primary endogeneous source is the patient’s alimentary canal.8 Dental prostheses and denture-soaking containers might represent a significant microbial reservoir for infection and cross-contamination but have not been evaluated. Investigations have shown that complete dentures from immunocompetent patients are capable of supporting the growth of microorganisms and can, therefore, serve as inadvertent transport mediums for potentially infectious organ

Exchange of Cadaveric Kidneys for Transplantation in Australia and New Zealand*

In the period from March 1970 to April 1978, 176 kidneys from 137 cadaver donors were exchanged, on the basis of HLA matching, between transplant centres throughout Australia and New Zealand. The kidneys were preserved by simple ice storage or machine perfusion, and transported by air in chipped ice. Total ischaemia times ranged from 3.5 to 28.6 hours and immediate function occurred in 52% of cases. Graft survival was 62% at one year, 51% at three years and 47% at five years, the corresponding patient survival rates being 86%, 74% and 71%. An average of 1.4 antigens mismatched was achieved, and 59% of recipients received kidneys with zero or one antigen mismatched. These kidneys survived better than those with two or more antigens mismatched, the difference being 12% at one year, and rising to more than 20% at five years. The results confirm the practicability and potential value of the Organ Sharing Scheme, and indicate that effective sharing of kidneys on the basis of zero HLA mismatches could substantially improve the current success rate of clinical cadaveric renal transplantation.

Epidemiology of Pseudomonas aeruginosa infections: determination by pyocin typing.

The epidemiology of hospital infections due to Pseudomonas aeruginosa was investigated by pyocin typing. The typing method, which determined the pyocin activity of clinical isolates of P. aeruginosa on 27 indicator strains, was 43.7% reproducible, but elimination of 9 indicator strains doubled the reproducibility and yielded more readable pyocin inhibition zones. Seventy-eight of 1,084 isolates (7.2%) were untypable. In the second part of the study, P. aeruginosa was isolated from 110 patients (5.4% of all admissions) in a 3-month period and typed with the revised method. Twenty pyocin types were identified, 10 of which were obtained from five or more patients. P. aeruginosa was isolated from 45 of 353 environmental samples, including water fountains, ice machines, bar soaps, and germicide solutions for toilet brushes. Twenty percent of the environmental samples were untypable but, among typable strains, the five most common environmental strains were the same as the strains most frequently isolated from patients. The organism was frequently isolated from noses (39%), throats (39%), and stools (29%) of patients with P. aeruginosa infections or colonizations in urine, sputum, surgical wounds, or skin lesions. Six of eight patients had P. aeruginosa in their tracheostomy wounds. Autoinfections by strains already acquired on carrier sites may be significant.

Indwelling arterial catheters as a source of nosocomial bacteremia. An outbreak caused by Flavobacterium Species.

Between mid-May and mid-October, 1973, 49 blood cultures from 14 patients in an intensive care unit were positive for flavobacterium species, Group II-b. We conducted an investigation to determine how patients were being infected with this unusual organism. Comparison of the 14 infected patients with 37 controls associated indwelling arterial catheters with subsequent flavobacterium bacteremia (p = 0.005). Risk of infection was greatest during the period in which blood gas determinations were done most frequently (the first three days of catheterization) and in which infected patients had more blood gas determinations than control patients with arterial catheters (p less than 0.05). Flavobacterium species was cultured from in-use arterial catheters, from stopcocks, and from ice in the intensive-care unit's ice machine; the catheters were probably contaminated by syringes that were cooled in ice before being used to obtain arterial specimens for blood gas determination. This outbreak calls attention to arterial monitoring systems as a potential source of nosocomial infection.