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A study comparing sterile and nonsterile urethral catheterization in patients with spinal cord injury.

This study was designed to determine the effect of sterile and nonsterile intermittent catheterization on the incidence of urinary tract infection (UTI) in patients after spinal cord injury. The study included 29 patients with neurogenic bladder dysfunction treated with intermittent catheterization. One group of 14 patients was on sterile catheterization; another group of 15 patients was on nonsterile catheterization. On a weekly basis, urine samples were obtained and analyzed. A total of 122 urine samples were analyzed. The patients on sterile catheterization had a 28.6% UTI incidence; the group using a nonsterile catheterization technique had a UTI incidence of 42.4%. The most common urinary pathogen in both groups was E. coli (65%). The cost of antibiotics for patients on the sterile catheterization program was only 43% of the cost of antibiotics for those on the nonsterile program. However, the sterile kits cost 371% of the cost of the catheterization kits for the patients in the nonsterile program, so the total cost of managing neurogenic bladder on the sterile program was 277% of the cost of the nonsterile program.

Bacterial Infections↗

Toxic effect of ethylene-oxide-sterilized freeze-dried bone allograft on human gingival fibroblasts.

Freeze-dried bone allograft (FDBA) which either had or had not been sterilized by exposure to ethylene oxide (EtO) prior to lyophilization was obtained from two commercial sources. EtO-sterilized FDBA was reexposed to EtO as a positive control. Gas chromatograph assays revealed that three out of four commercially obtained EtO sterilized FDBA had no detectable EtO, with one sample having 0.21 parts per million (PPM). Surprisingly, 0.24 PPM was detected in one sample which had not been sterilized with EtO gas. This was presumed due to contamination from a gas-sterilized rubber stopper. In the cell toxicity study, FDBA and human gingival fibroblasts (HGF) were added simultaneously, incubated for 72 h, and fixed and stained. Samples of FDBA sterilized with EtO which were free of EtO did not alter HGF growth. However, the positive control FDBA which contained 0.72 PPM EtO had a deleterious effect on HGF. FDBA with EtO residuals caused morphologic change in HGF.

Bone Transplantation↗

In vitro cytotoxicity testing of AB-polymer networks based on oligo(epsilon-caprolactone) segments after different sterilization techniques.

Recently developed versatile biodegradable polymeric biomaterial offer new therapeutic options in numerous medical fields. Biocompatibility is a crucial requirement for the biomedical application of biomaterials, including the sterilization of these materials with the use of accepted protocols. Ethylene-oxide (EO) and low-temperature plasma (LTP) sterilization are frequently used low-temperature sterilization technologies for heat-sensitive materials. The agarose diffusion assay is a recommended cell-screening test to assess the cytotoxicity of biomaterials in vitro. The sensitivity of the agarose assay can be increased by using a modified computer-based image-analysis system. The influence of EO and LTP sterilization on the cytotoxicity of a versatile polymer system of shape-memory polymer networks based on oligo (epsilon-caprolactone) dimethacrylate and n-butyl acrylate was investigated. Statistically significant differences in the rate of cell lysis after EO and LTP sterilization of the polymer samples were detected by using this modified quantification system. The influence of the different sterilization techniques on the cytotoxicity of the polymeric material, as well as the clinical relevance of the described differences, are discussed.

Animals↗

Analysis of sterilization protocols for peptide-modified hydrogels.

Concerns about the efficacy of ethanol disinfection for implanted biomaterials prompted investigation of an alternative sterilization process, ultraviolet irradiation, for terminal sterilization of N-isopropylacrylamide-based hydrogels containing biomimetic peptides. Ultraviolet irradiation is more easily applied on a laboratory scale than gamma irradiation or electron beam, two commercially utilized methods; thus, UVC irradiation was investigated as a low-cost sterilization procedure that might be performed in laboratories prior to in vivo studies. UVC irradiation at 400 muW/cm(2) for up to 15 h did not prevent growth of Escherichia coli within the hydrogels, while ethanol disinfection did prevent growth for the duration of the experiment (120 h). Furthermore, UVC irradiation caused progressive degradation of peptides containing the Arg-Gly-Arg (RGD) domain. UVC irradiation cannot be used as a terminal sterilization process for peptide-modified materials. The system used in this study is not intended to be adequate for evaluating the sterility of medical devices in accordance with current Good Manufacturing Practice (cGMP); however, it remains a useful, low-cost system for the preliminary evaluation of sterilization procedures in terms of their ability to eliminate pathogenic organisms while preserving the structure of biologically active molecules within in a laboratory setting. Ethanol treatment is still the preferred method for disinfection of bioactive materials containing peptides or UV-degradable groups.

Acrylamides↗

Comparison of three lasers for dental instrument sterilization.

The sterilization of dental instruments is an area of great interest and recent concern in the field of dentistry. The purpose of this study was to compare the ability of three lasers (argon, CO2, and NdYAG) to sterilize dental instruments. Endodontic reamers were contaminated with microorganisms, lased at various levels of energy, placed in Trypticase soy broth, incubated, and read for growth or no growth to determine sterility. Results indicated that the argon laser is capable of sterilizing selected dental instruments at the lowest energy level (1 watt for 120 seconds) of the three lasers tested. The other two lasers were able to sterilize the instruments also, but at higher energy levels. Results indicated all three lasers capable of sterilizing selected dental instruments; however, the argon laser was able to do so consistently at the lowest energy level of 1 watt for 120 seconds.

Argon↗

Involuntary sterilization of persons with mental retardation: an ethical analysis.

Legitimate concerns on the part of parents and guardians may lead to requests for sterilization of a mentally retarded person in their care. At the same time, mentally retarded persons must be protected from actions that do not serve their best interests. This paper will review the history of involuntary sterilization in the United States and evaluate the ethical arguments that are relevant to decisions about involuntary sterilization. While other, less permanent forms of contraception might be acceptable, involuntary sterilization ought not be performed on mentally retarded persons who retain the capacity for reproductive decision-making, the ability to raise a child, or the capacity to provide valid consent to marriage. Mentally retarded persons who lack capacity in those three areas should be considered for involuntary sterilization only when the procedure is necessary, sterilization would serve the best interests of the mentally retarded person, less intrusive and temporary methods of contraception or control of menstruation are not acceptable alternatives, and procedural safeguards have been implemented to assure a fair decision-making process.

Humans↗

Biomechanical comparison of human bone-patellar tendon-bone grafts after sterilization with peracetic acid ethanol.

Recent reports of disease transmission following ACL reconstruction with fresh-frozen non-sterilized allografts have highlighted the need for new sterilization techniques that do not impair the mechanical properties as it was shown for most of the current sterilization techniques. In this in-vitro biomechanical study, it was investigated if peracetic acid ethanol sterilization (PES) has any adverse effects on the mechanical properties of human bone-patellar tendon-bone grafts (BPTB). Paired human BPTB grafts either underwent PES or were used as fresh-frozen non-sterilized grafts. Viscoelastic properties (strain, creep) were analyzed during cyclic submaximal loading and mechanical properties were investigated during load-to-failure (LTF) testing. It was found that there were no differences in viscoelastic and mechanical properties between both groups. The findings of this study provide baseline data for future in vitro and in vivo analyses of this promising new sterilization technique for soft-tissue allografts.

Biomechanical Phenomena↗

Evaluation of the FemTest device pre- and post-sterilization.

A study was conducted at the Universidad Austral, Valdivia, Chile, School of Medicine, to evaluate the safety, ease of use and effectiveness of the FemTest device* (FT), a new instrument to evaluate tubal patency. A total of 110 interval women were admitted to the trial between February 1985 and August 1986, all of whom wanted to be sterilized. The mean age of the women was 32.2 years and the mean number of live births was 3.1. Women underwent FT and hysterosalpingography (HSG) procedures pre- and post-sterilization in order to compare the results. Sixty-seven women were surgically sterilized and forty-three women were sterilized with transcervical application of methylcyanoacrilate. Complications and complaints experienced by the study participants included mild to moderate discomfort during FT procedures. Assessment of patient discomfort was not done during the HSG procedures. FT and HSG findings agreed in 97.2% of the women prior to sterilization. The simplicity and effectiveness of the FT procedure suggests it will be an excellent method to test for tubal patency after a non-surgical female sterilization procedure.

Adult↗

Contraceptive female sterilization in Alabama: a replication of the WHO study.

The prevalence of female sterilization for contraceptive purposes has grown rapidly throughout the world, and is especially high in the United States. Yet the psychosocial impact of female sterilization is incompletely understood. Much of the previous research has been retrospective and has lacked comparison groups of women using other methods. Better designed, prospective studies have been needed, and the World Health Organization's Collaborative Prospective Study of Female Sterilization was conducted to address this need. No evidence was found in the WHO study of a significant impact of tubal ligation compared to other contraceptive methods on mental health, menstruation, or sexual satisfaction. The present study, a replication of the WHO study, compared 323 Alabama women undergoing elective contraceptive sterilization with 318 women using other techniques to control fertility. In general, the results supported the WHO study conclusions. Although sterilization produced a small increase in menstrual distress in Alabama, there were no significant differences between sterilization and comparison women in mental health or sexual satisfaction.

Adult↗

Salivary progesterone concentrations after tubal sterilization.

OBJECTIVE: To find out if ovarian endocrine function is hampered by laparoscopic tubal sterilization. METHODS: Salivary progesterone levels were measured in 55 women undergoing a laparoscopic tubal sterilization with Hulka or Filshie clips. The participants were 31-43 years old (mean 37) and were menstruating regularly. The saliva was collected every morning during three menstrual cycles: on the cycle preceding sterilization, and 3 and 12 months after the procedure. Salivary progesterone levels were determined by a radioimmunoassay. RESULTS: Total progesterone secreted in the luteal phase declined slowly after the sterilization, resulting in the lowest values 1 year after the procedure (1780 +/- 807 versus 2431 +/- 1187 pmol/L before surgery, P = .001). The luteal peak progesterone values were lowest 3 months after sterilization (277 +/- 137 pmol/L). Although the peak progesterone secretion seemed to have started to recover at 12 months (318 +/- 171 pmol/L), it was still significantly less than before surgery (378 +/- 150 pmol/L, P = .015). The length of the entire menstrual cycle and the lengths of the follicular and luteal phases were not affected. CONCLUSION: Although the menstrual pattern was not affected, laparoscopic tubal sterilization caused measureable changes in the luteal function. However, these changes may be temporary in nature.

Adult↗

The effects of sterilization techniques on the properties of intracanal instruments.

Three common sterilization techniques, namely, autoclaving (15 and 25 minutes at 250 degrees F.), salt sterilization (5 and 10 seconds at 480 degrees F.), and dry heat (one hour at 340 degrees F.), were used to sterilize 420 root canal reamers and files, both carbon and stainless steel. These intracanal instruments were then tested in tension. An extra eighty-four intracanal instruments were tested without being subjected to any sterilization techniques and served as controls. It was found that carbon steel intracanal instruments were affected more by the different modes of sterilization than were the stainless steel instruments. Time of sterilization did not seem to have an effect on the properties of either instrument.

Carbon↗

The effect of autoclave sterilization on endodontic files.

This study evaluates the effect of cyclic autoclave sterilization and simulated clinical usage on a mechanical property of one brand of stainless steel endodontic files. The angular deflection moments were measured by a torque apparatus approved by the American Dental Association for such purposes. Comparisons of values for sterilized and nonsterilized files were made. 1. A significant decrease in angular deflection values exists for stainless steel endodontic files having undergone ten cycles of autoclave sterilization versus files having undergone only two or five similar cyclings. 2. All file sizes (15, 20, 25, 30, 35, 40) tested in torsion were detrimentally affected by the autoclave sterilization. 3. Of the files investigated, sizes 35 and 40 were the most adversely affected by the steam-under-pressure sterilization. 4. The angular deflection values of those files subjected to repeated autoclavings were not decreased below the minimum value accepted by the American Dental Association for resistance to torquing forces. It can therefore be concluded that repeated sterilization of a stainless steel endodontic file does result in a significant reduction in the torque resistance of that file. This reduction of the metal property is not significant clinically, however.

Endodontics↗

Evaluation of the shelf life of sterile instrument packs.

No published studies have specifically addressed the shelf life of sterile packaging materials commonly used in dentistry. This study examined the effect of time on the sterile integrity: paper envelopes, peel pouches, and nylon sleeves. Seven thousand two hundred sample packs, each containing three glass rods, were prepared and steam sterilized. After sterilization, half the packs (control packs) were immediately opened and the contents were analyzed for bacterial contamination. The other half (test packs) were randomly sorted and stored in dental treatment operatories. At monthly intervals for 12 months, 100 packs of each type were similarly opened and analyzed. The contamination rates between the control packs were not significantly different from one another. Differences in contamination rates between control packs and test packs for both the paper envelopes (0.4% and 0.7%) and the peel pouches (0.2% and 0.2%) were also insignificant. However, a significant difference (p less than 0.01) between control and test packs (0.3% and 1.5%) was found for the nylon sleeves. This increase was not time related and was attributed to difficulty in removing the glass rods from the nylon packs in a sterile manner. The most important finding was the absence of a trend toward an increased rate of contamination over time for any pack type. This indicates that when these materials are placed in covered storage in dental operatories, a 12-month storage period is not detrimental to their sterile integrity.

Chi-Square Distribution↗

Multiple gamma radiation sterilization of polyester fibres.

Gamma radiation with a dose of 2.5 Mrad has been found to be suitable to sterilize polyethylene terephthalate (PET) bulk materials intended for biomedical applications. The radiation stability of PET bulk materials and fibre may not however be taken as identical due to the changes in the polymer structure during the processing of bulk materials for fibre. The chemical changes occurring in PET fibres during single and multiple (prolonged) sterilization in air were investigated. It was found that single sterilization (2.5 Mrad) itself affected the PET yarn and fibre. This was exhibited by the increase of crystallinity from 30.5 to 37% in the case of yarn and from 40 to 44% in the case of fibre. The breaking load of the yarn also increased from 441 g to 451 g. These changes were attributed to the degradation of PET in the amorphous region and the recombination of degraded aliphatic segments. Sterilization at higher doses affected the crystalline region which decreased the crystallinity, breaking load and molecular weight. For samples irradiated at 2.5 Mrad, the breaking load increased, though the dispersity increased. This was attributed to cross-linking by recombination. The increase in crystallinity also enhanced the breaking load of the samples. Higher doses of sterilization led to drastic microstructural and macrostructural changes as seen from the molecular weight. It was inferred that the changes in crystallinity and microstructure that occurred during multiple sterilization might affect the biocompatibility of the material.

Biocompatible Materials↗

Tissue response to commercial silicone and polyurethane elastomers after different sterilization procedures.

Two different commercial polymeric materials, a silicone and a polyurethane (PUR), were studied with regard to correlations between the chemical and physical compositions of the polymer surfaces and the biological response on implantation. Test specimens of the materials were manufactured according to standard procedures. The specimens were implanted in rats for 10 and 90 days. Before implantation the polymers were sterilized in three different ways, namely, beta irradiation, ethylene oxide sterilization and steam sterilization. The polymers were characterized before and after the implantation with respect to the chemical composition and the morphology of the surfaces. After implantation the biological response was evaluated by counting numbers of macrophages, giant cells, fibroblasts and other cells present at the surfaces. The thickness of the fibrous capsule surrounding the test specimens was measured at the thickest and thinnest parts. PUR surfaces showed signs of degradation already after sterilization and after 10 to 90 days of implantation, pits and cracks appeared, especially in the ethylene oxide sterilized samples. However, differences in the biological responses were small and independent of the sterilization method. After 10 days of implantation the capsule thickness and the amounts of cell material adhering at the surfaces were different, and it appears that the silicone rubber induces more tissue response than PUR. The differences in the early tissue response evened out after 90 days implantation time and a steady state situation evolved, which was similar for the silicone and the polyurethane.

Animals↗

Sterile water used for humidification in low-flow oxygen therapy: it is necessary?

Currently it is standard practice in many acute care hospitals to use only sterile water in humidifier reservoirs for the delivery of low-flow oxygen therapy. This practice is based primarily on the Centers for Disease Control's 1982 "Guideline for the Prevention of Nosocomial Pneumonia." The present study was designed to investigate and compare the bacterial contamination of tap water and sterile water used to fill clean (nonsterile) disposable oxygen humidifier reservoirs. Disposable oxygen humidification reservoirs were assembled weekly according to standard protocol and regulated to deliver oxygen, 4 to 6 L/min, continuously for 5 consecutive days. Each of 48 reservoirs was filled with either tap water (24) or sterile water (24) and cultured daily. All disposable equipment was discarded after the final culture on the fifth day. An aliquot of water was obtained daily from each reservoir and plated to trypticase soy agar pour plates and to a matched trypticase soy broth. Bacterial growth was observed on trypticase soy agar pour plates from 54 (45.0%) of 120 sterile water reservoir cultures and from 38 (31.7%) of 120 tap water reservoir cultures (p greater than 0.05). Bacterial growth from the matched trypticase soy broth cultures was observed only from two sterile water reservoirs. The microorganisms identified from the sterile water reservoirs included Enterobacter agglomerans and Serratia and Bacillus spp. The use of tap water for low-flow oxygen humidification was determined to be safe at our hospital by the infection control committee. This procedural change contributed approximately $6000 to the cost reduction efforts of the respiratory therapy department.

Centers for Disease Control and Prevention, U.S.↗

Effects of steam sterilization on the contents of sharps containers.

BACKGROUND: One form of medical waste known to be capable of transmitting disease is the contaminated sharp. Safe handling and disposal of sharps is an essential element of any infection control program. Many areas allow the on-site treatment of sharps containers. However, little information currently exists as to the most effective sterilization procedures and container designs. METHODS: This study was intended to evaluate the effect treatment with various autoclaves had on bacterial endospores present on strips or needled syringes. Strips contained 1.7 x 10(5) Bacillus stearothermophilus spores; syringes were soiled with equal numbers of spores or with spores plus blood. Syringes were tested capped and uncapped. A gravity-displacement autoclave and a high-vacuum autoclave were used. Strips and syringes were placed within sharps containers three quarters filled with representative materials. Six types of containers were tested. Containers were processed sitting up or on their sides. Processed strips and needles were aerobically cultured at 56 degrees C for 7 days. If sterilization was not accomplished initially, additional exposure time was added. RESULTS: (1) Soiled syringes were more difficult to sterilize than strips. (2) Capping or the presence of blood did not affect sterilization efficiency. (3) Container positioning was important only for the gravity-displacement autoclave. (4) Additional exposure time was required in the gravity displacement autoclave when sterilizing soiled syringes but not strips. (5) High-vacuum autoclaving killed all spore challenges within the normal processing interval. CONCLUSIONS: The data indicate that processing of sharps containers within a gravity-displacement autoclave appears to require extended exposure intervals to achieve sterilization.

Equipment Contamination↗

Sterilization in the northeast of Brazil.

Results of household surveys carried out in four states in the Northeast of Brazil showed that female sterilization is the most prevalent method among women who want no more children. Many women who indicated an interest in tubal ligation, however, had not been sterilized. Access to sterilization depends on the type of hospital in which the child was delivered and the type of delivery the woman had. Over 60% of the sterilized women reported that they had a tubal ligation at the time they were hospitalized for a cesarean delivery. Compared with unsterilized women, the sterilized women are characterized by relatively higher education levels and a greater likelihood of urban residence and were far more likely to have had cesarean deliveries and, therefore, to have qualified for postpartum sterilization on medical grounds.

Adolescent↗