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Safety and efficacy of ethylene oxide sterilized polyethylene in total knee arthroplasty.

Eleven unassembled metal backed patellar interfaces were inoculated with 0.1 ml of Sportol (Bacillus subtilis variety niger spore) and then assembled. Ten of the 11 implants were exposed to 1/2 of a standard ethylene oxide sterilization cycle. The remaining implant was left unsterilized as a control. All the implants were separately incubated in soybean casein digest broth for 7 days at 30 degrees to 35 degrees C and tested for positive growth of Bacillus subtilis. To measure residual ethylene oxide content, 4 ultrahigh molecular weight polyethylene tibial inserts were exposed to a full ethylene oxide sterilization cycle. The implants were removed from the sterilization chamber and tested for residual ethylene oxide at 3, 5, 8, and 9 days after sterilization using an exhaustive extraction headspace technique. Residual ethylene oxide was measured in 3 additional implants 26 days after sterilization. No growth of Bacillus subtilis occurred on any of the 10 inoculated and ethylene oxide sterilized metal backed patellar components, whereas positive growth occurred on the inoculated, unsterilized control implant. Residual ethylene oxide measured in the tibial inserts at 3, 5, 8, and 9 days after sterilization was 23, 15, 12, and 9 ppm, respectively. Twenty-six days after sterilization, residual ethylene oxide was below the minimum detectable level of the measurement technique (5 ppm).

Bacillus subtilis↗

Chemical sterilization of bacterially contaminated bone without destruction of osteogenic potential.

A method to sterilize bone that has been contaminated or to assure sterility of allografts would be quite useful in the practice of orthopedics. The literature documents the osteogenic potential of demineralized bone matrix, prepared by treatment with hydrochloric acid and ethanol. We became interested in whether these potent antibacterial agents could render contaminated bone sterile and thus usable. Thus, we tested immersion in 70% ethanol or 0.6 N hydrochloric acid as sterilization methods for contaminated bone specimens. Bone fragments were (heavily) surface contaminated for 30-60 s by immersion in a suspension of either Escherichia coli, Staphylococcus aureus, or Bacillus subtilis and then placed in either the ethanol or hydrochloric acid solutions for 15 min, 30 min, 1 h, 2 h, 4 h, or 8 h. Subsequently, they were incubated in broth culture for 14 days. Using 70% ethanol, 80-90% of contaminated bone specimens were sterile in 4 h and all were sterile in 8 h. Using 0.6 N hydrochloric acid, only 10% of bone specimens contaminated with Staphylococcus aureus, 60% with Escherichia coli, and 90% with Bacillus subtilis were sterile in 8 h. Consequently, 70% ethanol could possibly by used as an antiseptic or sterilizing agent for contaminated bone, although we feel that such bone should also be demineralized. Ethanol should not be used for routine treatment of mineralized cortical bone as it has been shown to diminish the already poor osteogenic potential of cortical bone.

Administration, Topical↗

Sterilization and its consequences.

UNLABELLED: The purpose of this review is to analyze critically the two techniques of sterilization (bilateral tubal ligation [BTL] and vasectomy) so that a physician may provide informed consent about methods of sterilization. A MEDLINE search and extensive review of published literature dating back to 1966 was undertaken to compare preoperative counseling, operative procedures, postoperative complications, procedure-related costs, psychosocial consequences, and feasibility of reversal between BTL and a vasectomy. Compared with a vasectomy, BTL is 20 times more likely to have major complications, 10 to 37 times more likely to fail, and cost three times as much. Moreover, the procedure-related mortality, although rare, is 12 times higher with sterilization of the woman than of the man. Despite these advantages, 300,000 more BTLs were done in 1987 than vasectomies. In 1987, there were 976,000 sterilizations (65 percent BTLs and 35 percent vasectomies) with an overall cost of $1.8 billion. Over $260 million could have been saved if equal numbers of vasectomies and BTLs had been performed, or more than $800 million if 80 percent had been vasectomies, as was the case in 1971. The safest, most efficacious, and least expensive method of sterilization is vasectomy. For these reasons, physicians should recommend vasectomy when providing counseling on sterilization, despite the popularity of BTL. TARGET AUDIENCE: Obstetricians & Gynecologists, Family Physicians LEARNING OBJECTIVES: After completion of this article, the reader will be able to predict the failure rates and likelihood of successful reversal of tubal ligation and vasectomy; to recall the difference in cost between the two sterilization procedures, and to describe the short-term and long-term complications associated with each of the two methods of sterilization.

Counseling↗

The effect of sterilization methods on the light transmission characteristics and structure of light-curing tips.

The purpose of this study was to investigate the effect of various sterilization methods on the light transmission and the structural characteristics of two light-curing tips. Twenty tips from two light-curing devices [Elipar II (EL) and Heliolux II (HL)] were classified into four groups. The tips in groups A to C were subjected to sterilization with 0.2% sodium dichloroisacyanurate solution (Presept), 2% glutaraldehyde solution (Cidex) (2 h cycle(-1)) and water-steam autoclave (120 degrees C, 1 bar, 12 min cycle(-1)), respectively. A total of 2100 sterilization cycles was performed for all methods tested. The transmitted light intensity (TLI) was measured at specific sterilization time intervals by a curing radiometer (Model 100, Demetron). The final % TLI reduction of the sterilized tips was calculated relative to the corresponding control ones. The topography and composition of the front curing tip surfaces were determined using scanning electron microscopy combined with electron probe microanalyser. Autoclaving caused the lowest final TLI decrease (EL: 15%, HL: 19%) compared with Presept (EL: 60%, HL: 42%) and with Cidex (EL: 68%, HL: 52%). Cidex yielded higher TLI drop than Presept for both types of tips examined. Elipar tips were found to be more sensitive than Heliolux tips to both chemical sterilization techniques. Total or partial coating of the tip surfaces with insoluble salts after sterilization with Presept and Cidex was detected, mainly composed of Ca, Cl, Al, Pd and Mg traces. No changes were noted on the surfaces after autoclave. Water-steam autoclave is safer than the 0.2% sodium dicloroisocyanorate and 2% glutaraldehyde chemical sterilization agents regarding the light transmission characteristics and the structure of the light-curing tips.

Dental Disinfectants↗

Sterilization method of platelet storage containers affects in vitro parameters.

BACKGROUND AND AIM: Four butyryl trihexyl phthalate plasticized polyvinyl chloride (BTHC-PVC) containers were compared for storage of leukoreduced platelet concentrates (LR-PC): three ethylene oxide (EtO) sterilized (Gambro, Haemonetics, Fresenius), and one steam-sterilized (Fresenius). METHODS: LR-PCs were made from 5 buffy coats and 300 ml Composol additive solution, and leukoreduced by filtration. Four LR-PCs were pooled and subsequently divided over the 4 BTHC-PVC bags to prevent donor-dependent differences, and sampled for in vitro analysis on day 1, 2, 5, 7 and 9. RESULTS: The pH values on day 9 were (mean +/- SD, n = 10): 7.12 +/- 0.03 (Gambro), 7.12 +/- 0.04 (Haemonetics), and 7.07 +/- 0.09 (Fresenius, EtO-sterilized) (not significantly different), vs. 6.91 +/- 0.12 (Fresenius, steam-sterilized; P < 0.001 vs. all EtO-sterilized bags). LR-PCs stored in the steam-sterilized bag exhibited significantly higher glucose consumption and lactate production (P < 0.001 vs. all EtO-sterilized bags). CONCLUSION: All BTHC-PVC containers allow storage of LR-PCs for up to 9 days with good in vitro parameters. However, the method of sterilization affects the storage conditions of the LR-PCs in these bags.

Blood Platelets↗

Soil sterilization effects on in situ indigenous microbial cells in soil.

Soil was sterilized by various procedures, and then the resident microorganisms were physically separated and concentrated from the soil for viewing by transmission electron microscopy as thin sections and frozen-etched preparation. Remaining cell viability in the soil was tested by conventional plating before and after enrichment culture. The soil proved to be sterile after treatment with 60Co radiation, prolonged autoclaving, prolonged dry heat application at 200C, or glutaraldehyde (if followed by subsequent milk heating), and could be considered sterile after OsO4 treatment. Treatment with glutaraldehyde alone, or 160C dry heat for 3 h, did not sterilize the soil. Cellular fine structure was latered or destroyed by the heat treatments, but was not affected to any extent by any of the other treatments including glutaraldehyde followed by milk heating. These findings are considered in relation to the residual biological information observable by electron microscopy in soil samples which have been sterilized to eliminate possible pathogens before handling of the soil. These findings are also considered with the objective of obliterating the fine structure of the indigenous microorganisms during soil sterilization so that electron microscopy studies can be made of microorganisms inoculated into and grown in the presterilized soil. These findings are considered in relation to the residual biological information observable by electron microscopy in soil samples which have been sterilized to eliminate possible pathogens before handling of the soil. These findings are also considered with the objective of obliterating the fine structure of the indigenous microorganisms during soil sterilization so that electron microscopy studies can be made of microorganisms inoculated into and grown in the presterilized soil.

Bacteria↗

Sterilization of talc for pleurodesis. Available techniques, efficacy, and cost analysis.

Although talc has been used as a pleurodesis agent since 1935, a sterilization protocol has not been established. We obtained USP asbestos-free talc from six different suppliers and sterilized each using dry heat, gamma irradiation, and ethylene oxide gas. Aerobic, anaerobic, and fungal cultures were obtained prior to sterilization, and 1, 30, and 90 days after sterilization. Bacillus species were cultured from all six unsterilized specimens and coagulase-negative Staphylococcus grew from two unsterilized specimens. No growth of organisms was found following any method of sterilization. The cost of sterilization per 5-g packet of talc was $4.74, $7.85, and $16.25 for heat, ethylene oxide, and gamma irradiation, respectively. In conclusion, untreated talc is not sterile. Sterilization by prolonged dry heat exposure, ethylene oxide gas, and gamma irradiation are all effective, with dry heat being the least expensive.

Ethylene Oxide↗

[Sterilization in the daily dental practice].

The different systems of sterilization used in dental practice are examined. Sterilization with dry heat is especially studied, dry heat being the most appropriate and convenient way of sterilizing in the dental practice. Tests made by Prof. Vannier of Paris and by the author, prove that when the instruments are well cleaned, sterilization with dry heat at 176 degrees F for 60 min destroys all kinds of septic germs. It is not necessary to sterilize at 230 degrees F or higher. It is recommended to use both a dry heat sterilizer and an autoclave. The latter being used to sterilize the tissues, gaze, rubber, paper or to perform a quick sterilization just prior to an operation.

Dental Instruments↗

Validation of a microwave sterilizer for injection ampules.

A program for validating the microwave sterilizer, which is a new type of sterilizer, was established and implemented. This program includes the following tests specific to microwave sterilizers: the internal pressure strength of ampules, the acceptable range of sterilizing temperature, performance and calibration of the infrared thermometer and the plane blackbody, maintaining of sterilizing temperature, the processing speed (sterilizing time), the unacceptable ampules selection mechanism, microwave leaks, and a microbiological challenge test of the ampule head space using a biological indicator. Injectable preparations of mecobalamin and diprophylline were used as models for validation of the microwave sterilizer. The bioburden approach was used for injectable mecobalamin preparation, and the over-kill approach was used for injectable diprophylline preparation. The basis for practical use of this microwave sterilizer has been confirmed by the establishment and implementation of this validation program.

Drug Packaging↗

Alternative methods of terminal sterilization for biologically active macromolecules.

The traditional perception within the pharmaceutical industry of the manufacture of injectable drug products is that active pharmaceutical ingredients (API) that are peptides, proteins or biopolymers, such as poly(DL-lactide) (PLA) and poly(DL-lactideco-glycolide) (PLGA), cannot be terminally sterilized. This perception exists largely because terminal sterilization is assumed by many to be only carried out by steam sterilization in a standard autoclave. Thus, it is understood that these API candidates must be manufactured by aseptic techniques. With the current technological advances in the area of protein and peptide sterilization, which has largely come from the food industry and has in recent years been developed for pharmaceutical use, techniques have been developed for the terminal sterilization of thermally sensitive APIs and biopolymers. In this review, the focus will be on the four major types of sterilization that are presented in the literature: (i) gamma-irradiation; (ii) e-Beam; (iii) natural light; and (iv) microwave. Each of these sterilization techniques present advantages and disadvantages for use in large-scale terminal sterilization of bioactive macromolecules.

Biopolymers↗

Variability in catheter microwave sterilization techniques in a single clinic population.

PURPOSE: We designed a survey to assess the microwave sterilization technique practiced by patients at our clinic who perform clean intermittent catheterization. MATERIALS AND METHODS: A 23-question survey addressing urinary catheter use and home sterilization techniques was mailed to 129 patients. A followup survey was mailed to 47 respondents who reported using a microwave oven to sterilize the catheters to assess the microwave technique further. RESULTS: Of the 129 initial surveys 84 (64%) were returned, while 40 (85%) of the 47 followup questionnaires on microwave sterilization were returned. All patients surveyed have used clean intermittent catheterization for at least 1 year and 75% have used it more than 5 years. Of the respondents 80% perform clean intermittent catheterization 4 to 5 times daily, although sterilization frequency varies from daily to less than once weekly. Of the respondents 71% reported no difficulty with microwave sterilization, although 31 (63%) reported a history of catheter melting during microwaving. Of the respondents 35% reported using a rotation table, all used a heat sink containing 1/2 to 4 cups of water, 39% used 500 to 1,000 W., 37% used greater than 1,000 W., 73% set the microwave for 6 minutes, others set it for 3 to 30 minutes and 98% used a power setting described as high, full, 10 or 100%. CONCLUSIONS: Significant variation exists in the cleaning and sterilizing techniques used by our patients, although they were given uniform written and verbal instructions. It is unclear from the data in the literature how this variation affects sterilization.

Ambulatory Care↗

[Research and development on microwave sterilization].

This paper reviews recent research and development on microwave sterilization, including the experiments of sterilization effects, the influence of microwave radiating on the media parameters, the development of microwave sterilizers and the study of sterilization mechanism. Many results show that the method of microwave sterilization is more easy-to-perform, economical and reproducible than the conventional autoclaving method. It is necessary to study the sterilization conditions through the experiments for different media and bacteria. The research on sterilization mechanism, especially non-thermal sterilization mechanism is still a hotpoint.

Bacteria↗

[A new method of testing the effectiveness of sterile packaging in general practice].

The aim of our study was to develop a practical test for assessing the effectiveness of the microbial barrier of packaging materials for sterile products. The suitability of the test was verified in the exemplary case of double-wrapped sterilized trays. During testing, the bacterial count of the ambient air was 35 and 440 colony-forming units/cubic metre. The test is based on the co-sterilization in the sterile packing of petri dishes containing CASO agar, which at the end of the test were investigated for re-contamination. The petri dishes covered the sterilizing sieves as completely as possible. After sterilization, the packaging was loaded 300 to 900 times at a pressure of 1 kg (5x/min). This was followed by incubation for 48 hours at 37 degrees C, and evaluation (No. of colonies). The ability of the agar to culture colonies of bacteria was preserved unchanged for a period of at least 3 weeks after sterilization. For double-wrapped trays it was shown that re-contamination increases with intensity of mechanical loading and the atmospheric bacterial count. Since the package was breached only for the analysis, confounding factors due to removal of contents for examination, were effectively excluded. This test procedure is characterised by simplicity in handling and high specificity. As a final pack test it effectively closes a gap in the quality assurance chain for sterile materials.

Agar↗

Long-term sterility of orthodontic-surgical appliances.

The aim of this study was to evaluate the long-term sterility of new dental appliances according to the non rigid wrapping employed and assess the effectiveness of sterilization in a steam autoclave at 134 degrees for 20 minutes using physical, chemical, and biological indicators. All the experimental (E) samples and the control samples (C) were assigned to one of three groups according to the type of packaging: paper bag (E1), paper/plastic pouch (E2), nylon tubing bag (E3). Each bag contained standardized orthodontic wires and brackets and sterility indicators. The samples were evaluated at the following experimental times: immediately, and 6, 12, 24 and 30 months post-sterilization. The samples were analyzed under aerobic and anaerobic conditions in keeping with the protocol currently in use at the Department of Microbiology, School of Dentistry, University of Buenos Aires. The group of control, non-sterilized samples (C1, C2, C3) were analyzed prior to the onset of the study, and were found to be contaminated. None of the sterilized samples in any of the three experimental groups evidenced contamination at any of the experimental times. The results showed that, under the present conditions, the packages and orthodontic appliances remained sterile for 30 months. These results show the importance of controlling sterility and the storage conditions over time for all the orthodontic/surgical appliances used in invasive treatments.

Dental Instruments↗

Sterilization beneath rings on dental instruments.

This study determined the effectiveness of standard methods of instrument sterilization beneath instrument rings. Sets of three types of dental instruments were contaminated with known amounts of bacterial spores (Bacillus stearothermophilus or Bacillus subtilis). Instrument rings were placed over the contamination and the instruments processed through standard cycles in a steam autoclave, an unsaturated chemical vapor sterilizer, a standard dry heat sterilizer, an ethylene oxide gas sterilizer or a 2.0% alkaline glutaraldehyde solution. Controls consisted of spore-contaminated instruments without rings that were not processed through any sterilizing method and that were processed through each sterilizing method. All instruments and their associated rings were cultured for the presence of live spores. The results indicate that the reliability of sterilization beneath the instrument rings used is greatest if the ringed instruments are processed through a steam autoclave or an unsaturated chemical vapor sterilizer.

Bacillus subtilis↗

Effectiveness of four sterilizing procedures on prophylaxis cups.

Though manufactured as a single use, disposable item, prophylaxis (prophy) cups are often cleaned, sterilized or disinfected, and re-used. The purpose of this study was to determine whether 1) sterilization of prophy cups is achieved during routine procedures 2) debris is completely removed after cleaning. Three types of prophy cups (250 of each type) were evaluated. Prophy cups were contaminated with a pumice slurry containing B. stearothermophilus spore. After contamination, cups were distributed equally between ultrasonic or manual cleaning, then further distributed to one of four sterilization procedures: ETO, chemiclave, autoclave, and glutaraldehyde (GLU) immersion (6 3/4 hours). Five cups served as control and were not subjected to sterilization. Additionally, 15 prophy cups were contaminated and immersed in GLU for 10 minutes. Results indicate sterilization may be achieved by all sterilization methods tested. However, recommended disinfection immersion time of 10 minutes for GLU was not effective in achieving adequate disinfection of prophy cups. Photomicrographs indicate debris remains trapped in prophy cups after manual or ultrasonic cleaning. Prophy cup sterilization may be achieved through standard routine sterilization procedures, but remaining debris is likely due to porosity of rubber and configuration of the cups. Time management, cost effectiveness, and sound clinical judgment suggest single use.

Dental Prophylaxis↗

Tubal sterilization and the long-term risk of hysterectomy.

To assess the effect of tubal sterilization on the risk of hysterectomy, we studied 7414 women aged 20 to 49 years who had had a tubal sterilization at a health maintenance organization between January 1, 1968, and December 31, 1983. Compared with a population-based cohort of nonsterilized women, women sterilized while 20 to 29 years old were 3.4 times more likely to have had a subsequent hysterectomy (95% confidence interval, 2.4 to 4.7). Adjustment for the effects of potential confounders with a subset of 276 women did not appreciably alter this association. For multivariate comparisons with 5323 wives of vasectomized men, there was no significant elevation in the risk of hysterectomy following sterilization among women sterilized while 20 to 29 years old. Tubal sterilization was not associated with hysterectomy for married women who underwent tubal sterilization at age 30 or older. These results do not support a biological basis for the relationship between tubal sterilization and hysterectomy.

Adult↗

Monitoring dental sterilizers' effectiveness using biological indicators.

The purpose of this study was to evaluate the effectiveness of dental office sterilizers as measured by their ability to kill bacterial spores present on biological indicator strips. The biological indicators used in this study contained two different spores, Bacillus stearothermophilus and Bacillus subtilis (Spordi, AMSCO/Medical Products). Ten spore test strips were sent to 87 dental offices; 51 sterilizers were tested. Office personnel were instructed to place four strips in the center of a normal sterilization load and process the load. The procedure was repeated on a second day. The processed strips, along with two unprocessed control strips, were returned by mail for laboratory culturing. The results indicated the overall failure rate (positive test) of sterlizers tested for both days was 51% at the culturing temperature of 37 degrees C and 33.3% at 55 degrees C. McNemar's test indicated a significant difference (p less than .03) in sterilization failures associated with the type and number of microorganisms present on the test strips. This study also showed that the more times a sterilizer was tested, the more likely a failure would occur. Overall, an alarming number of sterilizers (64.7%) were not effective in killing all the spores present on the indicator strips. When office personnel were given information for improving sterilizer performance, there was a noticeable reduction in sterilization failures following retesting.

Evaluation Studies as Topic↗