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Biomedical subjects

M S Favero

Publications and source records attributed to M S Favero.

At least 127 records · Page 7Linked to original sources
PubMed1967

Use of ultrasonic energy in assessing microbial contamination on surfaces.

Ultrasonic tanks were evaluated for their ability to remove viable microorganisms from various surfaces for subsequent enumeration. Test surfaces were polished stainless steel, smooth glass, frosted glass, and electronic components. The position of contaminated surfaces in relation to the ultrasonic energy source, distance of the ultrasonic source from the test surfaces, and temperature of the rinse fluid were some of the factors which influenced recovery. Experimental systems included both naturally occurring microbial contamination and artificial contamination with spores of Bacillus subtilis var. niger. The results showed that ultrasonic energy was more reliable and efficient than mechanical agitation for recovering surface contaminants. Conditions which increased the number and percentage of microorganisms recovered by ultrasonic energy were: using a cold rinse fluid, placing the sample bottle on the bottom of the ultrasonic tank, and facing the contaminated surfaces toward the energy source. It was also demonstrated that ultrasonic energy could be effectively used for eluting microorganisms from cotton swabs.

Journal Article↗
PubMed1966

Comparative levels and types of microbial contamination detected in industrial clean rooms.

The primary objective of this study was to determine quantitatively and qualitatively the predominant types of microbial contamination occurring in conventional and laminar flow clean rooms. One horizontal laminar flow, three conventional industrial clean rooms, and three open factory areas were selected for microbiological tests. The results showed that as the environment and personnel of a clean room were controlled in a more positive manner with respect to the reduction of particulate contamination, the levels of airborne and surface microbial contaminants were reduced accordingly. The chief sources of microbial contamination were associated with the density and activity of clean room personnel. In addition, the majority of microorganisms isolated from the intramural air by air samplers were those indigenous to humans. Studies on the fallout and accumulation of airborne microorganisms on stainless-steel surfaces showed that, although there were no significant differences in the levels of microbial contamination among the conventional clean rooms, the type of microorganism detected on stainless-steel surfaces was consistently and significantly different. In addition, the "plateau phenomenon" occurred in all environments studied. It was concluded that the stainless-steel strip method for detecting microbial accumulation on surfaces is efficient and sensitive in ultra-clean environments and is the most reliable and practical method for monitoring microbial contamination in future class 100 clean rooms to be used for the assembly of spacecraft which will be sterilized.

Air Microbiology↗
PubMed1966

Factors influencing the occurrence of high numbers of iodine-resistant bacteria in iodinated swimming pools.

It has been shown that, although iodinated swimming-pool waters are usually free from coliform bacteria and enterococci, the total counts frequently become relatively high. Pseudomonas alcaligenes and Alcaligenes faecalis have been shown to account for most of these high counts. It was of interest, therefore, to compare the microbial flora of four alternately chlorinated and iodinated swimming pools. By means of the membrane filter method and suitable selective media, examinations were made for total viable counts, coliform bacteria, enterococci, staphylococci, Streptococcus salivarius, and P. aeruginosa. Colonies also were picked from membrane filters incubated on standard plate count agar and identified. The results showed that, although viable counts were significantly higher during the iodinated periods, the specific types of bacteria determined were either fewer than or the same as in chlorinated periods. During chlorination, the predominant microbial flora consisted of staphylococci and members of the genus Bacillus. During iodination, however, the P. alcaligenes-A. faecalis group accounted for 92 to 99% of the microbial flora. The accumulation of high numbers of these bacteria was shown to be due to their iodine resistance and their ability to grow rapidly in pool water in the absence of free iodine.

Alcaligenes↗
PubMedDate not supplied

Recovery of bacteria from reprocessed high flux dialyzers after bacterial contamination of the header spaces and O-rings.

The Centers for Disease Control (CDC) have received reports of bacteremia in patients on high flux dialysis attributed to contamination of dialyzer header spaces or o-rings. A study was performed in which header spaces and o-rings of Hemoflow F-80 dialyzers (Fresenius AG, Bad Homburg, FRG) were exposed to an aqueous suspension of Xanthomonas maltophilia and Mycobacterium chelonae for 1 hour. After exposure, the dialyzers were reprocessed manually with 4% formaldehyde, 4% Renalin, 2.5% Renalin, or sterile water (SW) as a control, or with an automated reprocessing machine using 3.25% Renalin. After 48 hours the blood compartment (BC) was drained and rinsed twice with 500 ml of SW. Each BC sample was cultured. To simulate dialysis, separate circulates of SW were pumped through the DC and the BC. After 15 minutes, the BC circulate was cultured, headers were unscrewed, and o-rings, header caps, and fiber bundle ends were cultured. For each germicide, bacteria were recovered in low numbers, primarily from the o-rings and the o-ring groove in the header caps. In 38 tests, a total of 60 of 342 assays (17.5%) were positive. In only one of these tests one bacterial colony forming unit (cfu) was recovered from the BC circulate during simulated dialysis. It was concluded that if header spaces and o-rings are contaminated, bacteria could be sealed protectively from the germicide. However, concentrations of surviving bacteria were low, probably outside the BC, and did not effectively contaminate the BC circulate during simulated dialysis.

Bacterial Adhesion↗
PubMedDate not supplied

National surveillance of dialysis-associated diseases in the United States, 1988.

To determine trends in a variety of dialysis-associated diseases and practices, the Centers for Disease Control surveyed 1,734 chronic hemodialysis centers in the United States in 1988 in conjunction with the annual facility survey performed by the Health Care Financing Administration. The response rate to a mailed questionnaire was 91%. These 1,586 centers represented 107,804 patients and 28,501 staff members. Over the last 13 years, the incidence of hepatitis B virus (HBV) infection decreased from 3.0 to 0.2% among patients and from 2.6 to 0.1% among staff members. Over the same time, the prevalence of HBsAg-positivity declined from 7.8 to 1.5% among patients and from 0.9 to 0.3% among staff members. Hepatitis B vaccine was given by 90% of the centers. By the end of 1988, 17% of susceptible patients and 53% of susceptible staff members had received all three doses of hepatitis B vaccine. From 1982 to 1988, as a result of receiving vaccine, the prevalence of antibody to HBsAg increased from 12 to 20% among patients and from 18 to 54% among staff. The incidence of non-A, non-B hepatitis in 1988 was reported to be 1.0% among patients and 0.1% among staff members. Fifteen percent of the centers reported pyrogenic reactions in the absence of septicemia among their patients and 45% reported septicemia. The reported incidence of dialysis dementia among hemodialysis patients was 0.2%, with a case fatality rate of 25%. In 1988, 67% of centers reported that they reused disposable dialyzers; these centers treated 72% of the dialysis patient population. Among centers that reused disposable dialyzers, the average number of reuses ranged from 2 to 50 (mean, 11) and the maximum number of times a disposable dialyzer was reused ranged from 3 to 131 (mean, 28). Chemical germicides used for reprocessing dialyzers included formaldehyde; Renalin, a peracetic acid-hydrogen peroxide-based germicide; and glutaraldehyde-based germicides. Reuse of disposable dialyzers was not associated with any increased risk of acquiring HBV infection among either patients or staff. However, pyrogenic reactions occurring in clusters were more frequently reported in centers that reused conventional dialyzer membranes compared with centers that did not. This increased risk was only associated with centers that reused these dialyzers in a manual reprocessing system, a result consistent with those obtained in 1986 and 1987. Eighteen percent of centers reported treating at least some of their patients by high flux dialysis.(ABSTRACT TRUNCATED AT 400 WORDS)

Communicable Diseases↗
PubMedDate not supplied

Illness in hemodialysis patients after exposure to chloramine contaminated dialysate.

In September 1987, patients at an outpatient dialysis center were exposed to chloramine contaminated dialysate when the carbon filter in a recently modified water treatment system failed. Forty-one patients required transfusion to treat the resultant hemolytic anemia. Epidemiologic investigation demonstrated that the mortality rate among dialysis center patients increased during the 5 months after chloramine exposure when compared with the 12 months before chloramine exposure, but no deaths could be attributed to the exposure. Chloramine is commonly used as a disinfectant in municipal water supplies, and has previously been reported to cause hemolytic anemia in patients undergoing dialysis. Hemodialysis centers in cities that use chloramine in water supplies must design water treatment systems with adequate means for removing chloramine and must monitor processed water closely to ensure that chloramine contamination does not occur. Dialysis centers that make changes in their water processing systems should evaluate all components of the system before changes are made, and must ensure that after modifications are made, processed water meets the standards set by the Association for Advancement of Medical Instrumentation.

Ambulatory Care Facilities↗
PubMedDate not supplied

National surveillance of dialysis-associated diseases in the United States, 1989.

To determine trends in a variety of dialysis-associated diseases and practices, the Centers for Disease Control surveyed 1,867 chronic hemodialysis centers in the United States in 1989 in conjunction with the annual facility survey performed by the Health Care Financing Administration. The response rate to a mailed questionnaire was 92%. These 1,726 centers represented 122,734 patients and 32,486 staff members. The following results were found. 1) During the last 14 years, the incidence of hepatitis B virus (HBV) infection decreased from 3.0 to 0.1% among patients, and from 2.6 to 0.1% among staff members. Over the same time, the prevalence of hepatitis B surface antigen (HBsAg) positivity declined from 7.8 to 1.4% among patients and from 0.9 to 0.3% among staff members. Hepatitis B vaccine was given by 92% of the centers. By the end of 1989, 19% of susceptible patients and 55% of susceptible staff members had received all three doses of hepatitis B vaccine. From 1982 to 1989, as a result of receiving vaccine, the prevalence of antibody to HBsAg (anti-HBs) increased from 12 to 19% among patients and from 18 to 54% among staff. The incidence of non-A, non-B hepatitis in 1989 was reported to be 0.7% among patients and 0.1% among staff members. 2) Twenty-two percent of the centers reported pyrogenic reactions in the absence of septicemia among their patients, and 51% reported septicemia. 3) The reported incidence of dialysis dementia among hemodialysis patients was 0.2%, with a case fatality rate of 23%. 4) In 1989, 68% of centers reported that they reused disposable dialyzers; these centers treated 73% of the dialysis patient population. Among centers that reused disposable dialyzers, the average number of reuses ranged from 1 to 50 (mean, 12) and the maximum number of times a disposable dialyzer was ever reused ranged from 3 to 150 (mean, 28). Chemical germicides used for reprocessing dialyzers included formaldehyde, Renalin (a peracetic acid-hydrogen peroxide-based germicide), and glutaraldehyde-based germicides. Reuse of disposable dialyzers was not associated with any increased risk of acquiring HBV infection among either patients or staff. However, pyrogenic reactions occurring in clusters were reported more frequently in centers that reused conventional dialyzer membranes compared with centers that did not. This increased risk was associated only with centers that used Renalin or glutaraldehyde for reprocessing (not formaldehyde) and occurred with both automated and manual reprocessing systems.(ABSTRACT TRUNCATED AT 400 WORDS)

Dementia↗
PubMedDate not supplied

National surveillance of dialysis-associated diseases in the United States, 1987.

The Centers for Disease Control surveyed 1,630 chronic hemodialysis centers in the United States in 1987 in conjunction with the annual facility survey done by the Health Care Financing Administration. Information was obtained on the following diseases and practices: 1) hepatitis B virus (HBV) infection in patients and staff members; 2) infection control procedures for hepatitis B surface antigen (HBsAg)-positive patients; 3) frequency of HBsAg serologic screening; 4) use of hepatitis B vaccine; 5) non-A, non-B hepatitis in patients and staff members; 6) pyrogenic reactions and septicemia; 7) dialysis dementia; 8) new dialyzer syndrome; 9) high flux dialysis; 10) reuse of dialyzers, dialyzer caps, bloodlines, transducer filters; 11) cleaning and disinfection procedures; and 12) human immunodeficiency virus (HIV) infection. The response rate to a mailed questionnaire was 91%. These 1,486 centers represented 97,225 patients and 27,123 staff members. During the last 12 years, the incidence of HBV infection decreased from 3.0% to 0.2% among patients and from 2.6% to 0.1% among staff members. Over the same time, the prevalence of HBsAg-positivity declined from 7.8% to 1.7% among patients and from 0.9% to 0.4% among staff members. Hepatitis B vaccine was given by 88% of the centers. By the end of 1987, 14% of susceptible patients and 49% of susceptible staff members had received all three doses of hepatitis B vaccine. From 1982 to 1987, as a result of receiving vaccine, the prevalence of antibody to HBsAg (anti-HBs) increased from 12% to 18% among patients and from 18% to 50% among staff. The incidence of non-A, non-B hepatitis in 1987 was reported to be 1.2% among patients and 0.2% among staff members. Fourteen percent of the centers reported pyrogenic reactions among their patients, and 46% reported septicemia in the absence of pyrogenic reactions. Pyrogenic reactions were significantly more likely to be reported by centers that practiced high flux dialysis. The reported incidence of dialysis dementia among hemodialysis patients was 0.2%, with a case fatality rate of 29%. Among patients developing dialysis dementia, the case fatality rate was higher in those centers that used deionization (DI) without reverse osmosis (RO) (47%) compared with centers that used RO (28%) (not significant, p greater than 0.05). In 1987, 64% of centers reported that they reused disposable dialyzers. These centers treated 70% of the dialysis patient population.(ABSTRACT TRUNCATED AT 400 WORDS)

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Effect of chemical germicides on the integrity of hemodialyzer membranes.

Epidemiologic investigations of bacteremia in dialysis patients by the Centers for Disease Control (CDC) identified an association with the use of dialyzers disinfected with a specific chemical germicide. A collaborative study by the CDC and the Food and Drug Administration (FDA) was conducted to determine the effect of dialyzer disinfectants on five types of dialyzer membranes: three cellulosic (Cuprophan, cellulose acetate, cuprammonium rayon); and two synthetic (polysulfone, polyacrylonitrile). The disinfectants tested were: 4% formaldehyde; Renalin; Cidex Dialyzer; Sporicidin HO; Warexin; and RenNew-D. Water was the control. Dialyzers were reprocessed up to 15 times. Each reprocessing consisted of rinsing, air-leak testing, filling with fresh disinfectant, and storing for 2 to 4 days. After 15 reprocessings or air-leak failure, each dialyzer was microbiologically challenged for membrane integrity. Membranes exposed to Renalin, Cidex Dialyzer, and water passed all tests. Cellulosic membranes exposed to Warexin failed all tests after 2 to 9 reprocessings. Cellulose acetate membranes exposed to Sporicidin HD failed microbiologic testing. One polysulfone dialyzer exposed to RenNew-D and one exposed to 4% formaldehyde failed microbiologic testing. These results and those obtained from epidemiologic studies suggest that membrane integrity testing (e.g. an air-leak test) should be an integral part of dialyzer reprocessing.

Biocompatible Materials↗