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Biomedical subjects

M S Favero

Publications and source records attributed to M S Favero.

At least 91 records · Page 5Linked to original sources
PubMed1979

Stability of a reference panel of lyophilized hepatitis B antigens and antibodies.

A lyophilized hepatitis B working/reference panel has been prepared for use in standardization tests. This panel includes HBsAg, anti-HBs, HBeAg/anti-HBe and subtype reagents. Quantitative analysis of the HBsAg reagents indicates that at a storage temperature of -20 degrees C, only 1 log at maximum of RIA counts per minute would be lost in 95 years. After storage at -20 degrees C for 1 year, there has been no loss of reactivity in any of the tests used to detect HBsAg, anti-HBs, HBeAg/anti-HBe or subtypes.

Antibodies, Viral↗
PubMed1979

Bacterial and endotoxin permeability of hemodialysis membranes.

Dialysis fluids containing at least 10(7) bacteria per milliliter and as much as 12,500 ng of endotoxin equivalents per milliliter were dialyzed and ultrafiltered with three types of disposable hemodialyzers. Neither bacteria nor endotoxin, as measured by the Limulus lysate assay, was detected in the sterile compartment despite ultrafiltration. Under these favorable conditions for endotoxin transfer, the maximum transfer rate was calculated to be less than 3.5 ng of endotoxin equivalents per hour. At this rate, it is unlikely that pyrexia during hemodialysis is due to the transfer of endotoxin across an intact dialyzing membrane. Provided that the integrity of the dialyzing membrane is maintained, this investigation indicates that the risk of endotoxemia or bacteremia associated with the use of contaminated dialysis fluids is negligible.

Bacterial Infections↗
PubMed1979

Air sampling for hepatitis B surface antigen in a dental operatory.

Forty samples of air with a mean sample volume of 104 liters were collected during the treatment of patients whose blood was positive for HBsAG: no samples contained HBsAG and occult blood. These findings suggest that, if environmentally mediated transmission of hepatitis B occurs in the dental operatory, it is more likely to occur through contact with contaminated surfaces than through the airborne route.

Air↗
PubMed1979

Guidelines for the care of patients hospitalized with viral hepatitis.

For years patients hospitalized with viral hepatitis have been placed in two categories of isolation--enteric precautions and blood precautions. This strategy was based on the inability to differentiate between hepatitis A and B and on the assumption that feces and blood from patients with either type might be infective. It is now known that patients with hepatitis A do not pose a problem of disease transmission through direct contact with blood, and although blood of patients with hepatitis B may be infective, the virus is not transmitted via feces. The enteric route is the principal mode of transmission for hepatitis A, but maximal levels of hepatitis A virus excretion occur before the onset of jaundice. Non-A, non-B hepatitis is similar epidemiologically to hepatitis B. Thus, the major thrust for caring for patients hospitalized with viral hepatitis is toward blood precautions; the same precautions used when handling feces, urine, and excretions from all other hospitalized patients are appropriate for patients admitted with a diagnosis of hepatitis A.

Bedding and Linens↗
PubMed1978

Growth characteristics of atypical mycobacteria in water and their comparative resistance to disinfectants.

With the increasing significance of group IV atypical mycobacteria as etiological agents in a variety of infections, studies were conducted to determine their growth capabilities in water and their comparative resistance to disinfectants used to decontaminate hospital equipment. Isolates of Mycobaterium chelonei (TM strains) from peritoneal fluids of patients and peritoneal dialysis machines were able to multiply in commercial distilled water, with generation times at 25 degrees C ranging from 8 to 15 h. Levels of 10(5) to 10(6) cells per ml were attained, and these stationary-phase populations declined only slightly over a 1-year period. Results of studies to determine resistance to disinfectants showed the following. (i) TM strains of M. chelonei cultured in commercial distilled water showed survivors in 2% aqueous formaldehyde (HCHO) solutions up to 24 h; in 8% HCHO, only a 2-log reduction in viable counts was observed over a 2-h sampling period. Reference ATCC strains of M. chelonei and M. fortuitum were rapidly inactivated, with no survivors after 2 h of exposure to 2% HCHO or 15 min of exposure to 8% HCHO. (ii) In 2% alkaline glutaraldehyde, TM strains survived 60 min. whereas ATCC strains showed no survivors after 2 min of contact time. (iii) All M. chelonei and M. fortuitum strains survived 60 min of exposure to concentrations of 0.3 and 0.7 microgram of free chlorine per ml at pH 7.

Chlorine↗
PubMed1978

Evaluation of a finger prick blood collection method for the seroepidemiology of hepatitis B.

A finger prick-swab method of blood specimen collection was qualitatively and quantitatively compared with the conventional venipuncture method for HBsAg and anti-HBs determinations by radioimmunoassay (RIA). The new method consisted of pricking the finger, collecting 0.1-0.2 ml of blood with a cotton-wool swab, and eluting the swab in 1 ml of 1% bovine albumin in saline containing 0.1% sodium azide. Using chimpanzees seropositive for HBsAg or anti-HBs, comparisons were made of RIA results of: (a) whole blood, haemolysed blood, serum, and plasma; (b) paired finger prick samples and serum; (c) dilutions of finger prick samples and serum; and (d) different volumes of blood on swabs. Field studies were carried out at two institutions where hepatitis B was hyperendemic to compare results from paired finger prick and serum specimens assayed by the RIA and haemagglutination techniques. The laboratory studies showed that swab RIA values for anti-HBs were significantly lower than serum values and that for HBsAg, swab values were significantly higher than serum values. In HBsAg tests, the field studies showed 100% agreement between the two methods; in anti-HBs tests, the finger prick method showed 85% agreement with positive sera. Because of the logistics of collecting and processing blood serum, the finger prick-swab technique may be a valuable aid in large-scale seroepidemiological surveys for hepatitis B.

Antibodies, Viral↗
PubMed1977

Viral hepatitis B: aspects of environmental control.

In recent years it has become increasingly evident that viral hepatitis type B is a major disease problem among patients and/or health professionals associated with environments such as hemodialysis centers, dental operatories, clinical laboratories, and institutions for the mentally retarded. Studies have incriminated the intramural environment as well as specialized equipment and procedures as important factors in disease transmission. With hepatitis B surface antigen (HBsAg) as a marker of potentially infectious blood or body fluids such as saliva, it is possible to assess the environmental role in transmission of hepatitis B by use of a swab-rinse technique coupled with radioimmune assay. Assay procedures have been developed and utilized for detecting HBsAg on surfaces and in air and for quantitating of HBsAg in thermal and chemical inactivation studies. Specific decontamination strategies and recommendations for sterilization or disinfection procedures are described.

Cross Infection↗
PubMed1976

Hepatitis B surface antigen in saliva, impetiginous lesions, and the environment in two remote Alaskan villages.

A study was conducted in an area of hepatitis B hyperendemicity to determin whether contact with infective bodily secretions or contaminated environmental surfaces could be involved in the transmission of the hepatitis B virus. Hepatitis B surface antigen was detected in gingival swab, saliva, and impetiginous lesion exudate samples from children. Hepatitis B surface antigen also was found in swab samples of surfaces frequently touched or placed in the mouth. In the absence of classical exposure to infectious blood or blood products, these findings suggested that, in a crowded home environment, saliva and cutaneous exudates containing hepatitis B virus may play a role in the transmission of hepatitis B.

Alaska↗
PubMed1976

An air sampling technique for hepatitis B surface antigen.

A filter-rinse technique capable of detecting low levels of airborne hepatitis B surface antigen (HBsAg) was devised and evaluated. Laboratory tests showed the procedure to have an efficiency of 22% with a coefficient of variation of 11% and a capability of detecting as little as 5 x 10(-5) ml of aerosolized antigen positive serum in a single air sample. The technique was field-tested in a hemodialysis center serving a patient population with a high prevalence of HBsAg seropositivity. The antigen was not detected in any of 60 air samples collected under conditions favoring the occurrence of aerosols.

Aerosols↗
PubMed1975

Pyrogenic reactions during haemodialysis caused by extramural endotoxin.

Between July 24 and Aug. 19, 1974, an outbreak of pyrogenic reactions occurred in patients at a private haemodialysis centre in a suburb of Washington, D.C. 49 reactions characterised by chills, fever, and hypotension occurred in twenty-three of the seventy patients dialysed during this period. No infections could be documented in any of the affected individuals. Despite the fact that only low levels of gram-negative bacterial contamination of the haemodialysis system were found, high levels of endotoxin contamination of dialysis fluid and endotoxaemia in patients experiencing overt reactions were recorded using the Limulus lysate test. The cause of these reactions was traced to an increase in endotoxin contamination of the tap water used to prepare dialysate, possibly caused by an increase in the algae levels in the local water source. The installation of a reverse osmosis system for water treatment may be a solution to the problem of endotoxin contamination of water used to prepare dialysis fluid.

Adult↗
PubMed1975

Bacteriological evaluation of an ultra-pure water-distilling system.

A prototype distillation and storage system with recycle for producing ultrapure water was monitored for bacteriological contamination during a period of 24 months. Naturally occurring Pseudomonas aeruginosa and P. cepacia were found to grow rapidly to levels of about 10(5)/ml in water taken from the storage reservoir and also in commercially prepared distilled water. The system was found to eliminate bacterial contaminants introduced into the still with the feed water, but the reservoir, once contaminated, remained contaminated during prolonged recycle, After a single treatment with free chlorine, the entire system remained uncontaminated until accidental or purposeful shutdown.

Pseudomonas↗
PubMed1975

Method for collecting naturally occurring airborne bacterial spores for determining their thermal resistance.

The ability to determine the thermal resistance of naturally occurring airborne bacterial spores associated with spacecraft and their assembly areas has been hindered by lack of an effective collecting system. Efforts to collect and concentrate spores with air samplers or from air filters have not been successful. A fallout method was developed for this purpose and tested. Sterile Teflon ribbons (7.6 by 183 cm) were exposed in pertinent spacecraft assembly areas and subsequently treated with dry heat. Thermal inactivation experiments were conducted at 125 and 113 C. Heating intervals ranged from 1 to 12 h at 125 C and 6, 12, 18, and 24 h at 113 C. Eight hours was the longest heating time yielding survivors at 125 C, whereas survivors were recovered at all of the heating intervals at 113 C. D125C values were calculated using the fractional-replicate-unit-negative technique of Pflug and Schmidt (1968) and ranged from 25 to 126 min. This variation indicated that the most probable number of survivors at each heating interval did not fall on a straight line passing through the initial spore population. However, the most-probable-number values taken alone formed a straight line suggesting logarithmic thermal destruction of a subpopulation of spores with a D125C value of 6.3 h.

Air Microbiology↗
PubMed1975

Microbial contamination of mist therapy units on six pediatric wards.

A study was conducted in six pediatric wards to investigated factors that influence microbial contamination of mist therapy units. Most samples from nebulizer reservoirs were positive for gram-negative bacilli which multiplied rapidly in distilled water and reached levels as high as 3.0 X 10(8) viable microorganisms per ml. High prevalence rates of Pseudomonas aeruginosa and coliform bacteria as well as high levels of gram-negative bacilli were found to be associated with infrequent and inadequate cleaning and disinfection of the nebulizing equipment. In one of the wards exhibiting high rates, a move to new quarters permitted the implementation of improved cleaning and maintenance procedures for mist therapy units. The result was a significant reduction of microbial contamination. This study reemphasizes the role of microbiological surveillance in assuring proper care of nebulizing equipment in the hospital.

Aerosols↗