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PubMed2004

An investigation of the microbial contamination of dental unit air and water lines.

AIM: The objective of this study was to measure the microbial contamination released from dental unit air lines (DUAL) and dental unit water lines (DUWL). MATERIALS AND METHODS: Emissions from DUAL and DUWL from five dental units supplied by a central water source (tap) and a centralised air supply were sampled three times over a five- week period. Air was forced through sterile water and then plated onto selective agar using apparatus designed to spread the sample solution evenly, and then incubated at room temperature for seven days. Colonies were then counted and the concentration of bacteria present was determined and expressed as colony forming units per millilitre (cfu/ml) per minute. The same procedure was used to evaluate five other dental units, which had attached independent water reservoir (bottle) systems (IWR). Only deionised water was added to the bottles and unit waterlines were cleaned weekly with alkaline peroxide based solution. Values were expressed as cfu/ml. RESULTS: Air and water specimens obtained from dental units supplied with tap water had microbial counts significantly (t-test, p < 0.05) greater than IWR dental units. CONCLUSIONS: Results indicate that IWR can reduce the numbers of micro-organisms released from DUWL. However, the effectiveness of such systems should be routinely monitored. Emissions from DUAL seems to reflect the levels of microbial contamination present in DUWL.

Air Microbiology↗

PubMed2003

Microbial contamination of cellular products for hematolymphoid transplantation therapy: assessment of the problem and strategies to minimize the clinical impact.

BACKGROUND: Hematopoietic progenitor stem cells (HPSC) are a specialized transfusion product used for transplantation. Microbial contamination may occur during harvest or subsequent manipulation of these cells. The same difficulties in ensuring a safe, sterile, final product are faced in the preparation of other cell-therapy products directly obtained from donors. Detection of contamination is problematic, and the clinical significance of infusing contaminated HPSC is controversial. METHODS: Chimeric Therapies' manufacturing and clinical experience with BM HPSC products and validation of a culture method for detection are described. In addition, this paper reviews the literature concerning contaminated blood products, including rates and circumstances of contamination, organisms, methods of detection, and the clinical significance of infusion of contaminated products. RESULTS: Seven of 33 BM harvest products received at Chimeric Therapies were culture positive for skin commensal organisms. Three of seven were culture positive in the infused product. This compares with literature reports of 0-42%. No patients had significant infusion reactions or evidence of infection related to the contamination. DISCUSSION: The risks associated with microbial contamination with skin commensals are insignificant compared with other components of transplantation. Contamination with pathogens can be eliminated with careful good manufacturing practices (GMP). A series of practical recommendations are presented for the reduction of contamination in HPSC and cell-therapy products.

Cell Culture Techniques↗

PubMed1996

Microbial contamination of dental unit waterlines: current preventive measures and emerging options.

Various approaches to prevention and control of microbial contamination of dental unit water are evolving. Currently available methods and emerging technologies are reviewed here in the context of contemporary federal regulatory and advisory agency positions on water quality in the dental operatory. Clean water systems, fully autoclavable systems, and a variety of devices designed to provide physical barriers to the influx and accumulation of microbial contaminants can all be used to assure satisfactory quality for coolant and irrigant water. There is one important proviso: all require a commitment to maintenance if they are to be deployed successfully. Stricter adherence to American Dental Association/American National Standards Institute standards in manufacturing and production and compliance with federal regulatory marketing procedures for equipment and devices would do much to advance the cause of dental unit water quality control.

Biofilms↗

PubMed1996

The effect of a portable HEPA-filtered body exhaust system on airborne microbial contamination in a conventional operating room.

OBJECTIVE: To study the effect of a portable HEPA-filtered air exhaust system (Stackhouse Freedom Surgical Helmet System) on airborne microbial contamination in a modern conventional operating room. DESIGN AND SETTING: Microbial air sampling was done with a two-stage Anderson sampler at the wound site during 46 total joint replacements. All operations were performed by the same surgeon in the same operating room at a large community hospital. RESULTS: In 18 cases done without air exhaust hoods, the number of bacterial and fungal colony-forming units (CFU) ranged from 0.6 to 11.7 (mean, 3.6). Air sampling during 28 operations with the operating team in air exhaust hoods revealed a mean of 3.6 CFU (range, 0 to 11.4). Bacterial CFU averaged 3.4 without hoods and 3.2 with exhaust hoods. Coagulase-negative staphylococci were the most common isolates (48% of isolates with hood, 55% without hood). No infections occurred. CONCLUSION: We concluded that these air exhaust hoods did not lower airborne microbial contamination detectable with this air sampling method, as compared to standard head cover and mask, in a modern conventional operating room.

Air Microbiology↗

PubMed1998

Microbial contamination of 'sterile water' used in Japanese hospitals.

We examined the following samples of water from 10 hospitals for microbial contamination: water obtained using an ultra filtration system (UF water), a reverse osmosis system (RO water), a water distillation system (distilled water) and tap water. UF water and RO water are used for handwashing before surgery, and distilled water for the preparation of drugs. All 10 samples of tap water examined were contaminated with < 10 colony forming units (cfu)/mL. Thirteen (68%) of 19 samples of UF water, nine (53%) of 17 samples of RO water and 15 (79%) of 19 samples of distilled water were contaminated with 10(1)-10(4) cfu/mL. The majority of micro-organisms were non-fermentative bacteria such as Sphingomonas paucimobilis and CDC gr. IV C-2. Japanese hospitals commonly use UF water and RO water for preoperative handwashing under the assumption that it is sterile. Our results suggest, however, that these types of water are inferior microbiologically to tap water. Distilled water from the dispensary was also contaminated with micro-organisms. The available chlorine content of tap water was 0.17-0.42 ppm and that of UF water (from tap water) 0-0.06 ppm. There was no available chlorine in RO water or distilled water (each from tap water). The reduction or disappearance of available chlorine appears to be associated with microbial contamination of UF water, RO water and distilled water.

Chlorine↗

PubMedDate not supplied

Use of a newly developed rapid microbial ATP bioluminescence assay to detect microbial contamination on poultry carcasses.

A newly developed rapid microbial ATP bioluminescence test (R-mATP) was shown to be an adequate means to assay the microbial load of poultry carcasses. This assay utilizes differential extraction and filtration to separate somatic from microbial ATP in a very rapid timeframe. The assay requires approximately 5 min to complete; approximately 3.5 min to sample and 90 s analytical time. Correlation coefficient (r) between aerobic colony counts and R-mATP test results (n=329) was 0.82. Post-test probabilities to correctly classify carcasses with different levels of microbial contamination were as high as 98% for samples of > or = 3.5 log aerobic CFU per ml. Given the rapidity of this assay, the R-mATP holds potential for monitoring the microbial load of carcasses at poultry-processing critical control points. Other potential applications of this new version of the microbial ATP bioluminescence test are discussed.

Adenosine Triphosphate↗

PubMedDate not supplied

Microbial contamination of haemodialysis catheter connections.

Bacterial contamination and colonisation of the haemodialysis catheter is a reason for infection in dialysis patients. One reason for contamination may be frequent routine connections at the beginning, during and end of dialysis. Higher infection rates observed with double lumen catheters may be due to the absence of the sterile, disposable device that is fitted between the blood tubing and the catheter hubs with single lumen catheters. A sterile, disposable extension was implemented at the author's unit for use in dialysis with double lumen catheters. The proximal and distal ends of the extension were assessed for microbial contamination after standard dialysis. Results show microbial contamination in almost 30% of the samples retrieved from the extensions. Experiences in PD and the behaviour of skin bacteria on polymers, suggest that disposable extensions might have the potential to serve as a barrier or absorber for bacterial contamination.

Asepsis↗

PubMed2005

Risk of microbial contamination of unit-dose eyedrops within twenty four hours after first opening.

The purpose of this study was to evaluate the risk of microbial contamination of sterile, preservative-free, unit-dose ocular medications within 24 h after the first opening. Four different unit-dose ocular medications (cromolyn sodium, timolol, gentamicin sulfate, and betamethasone) in 1 mL containers, were tested. After opening, the preparations were stored in an acrylic protector with or without cap, at room temperature or in a refrigerator at 4 degrees C. Samples were collected for microbiological cultures at 0, 4, 10, 14, and 24 h after opening from the identical container. No bacteria or fungus was detected in the samples throughout the period of the study. Microbial air contamination of the experimental environment was also studied. The culture results of environmental microbial air contamination were positive for both bacteria and fungi. This study suggests that unit-dose eyedrops remain free of microbial air contamination for up to 24 h after the first opening.

Administration, Topical↗

PubMed1986

Studies on microbial contamination of reused disposable plastic insulin syringes.

The microbial contamination of reused disposable insulin syringes and bottles was studied. Fourteen patients, aged 16-64 years, took part in the study. 50 syringes and 52 bottles were examined for sterility at different stages of use. Twelve (24%) syringes and 4 (8%) bottles were found to be contaminated by micro-organisms, although only in low numbers. The micro-organisms recovered belonged to the normal skin flora of man.

Adolescent↗

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↗

PubMed1996

Microbial contamination of blood conservation devices during routine use in the critical care setting: results of a prospective, randomized trial.

OBJECTIVES: To compare microbial contamination of two different blood conservation devices; to determine if there was an association between contamination of the blood conservation devices and clinical infections; to determine if there was a significant user preference for either of the two devices. DESIGN: Prospective, randomized trial. SETTING: Medical, neurosurgical, and spinal cord intensive care units of an urban, university hospital. PATIENTS: Forty patients who required clinically indicated intrafierial catheters placed at new sites. INTERVENTIONS: The two most widely available blood conservation devices at the time of the study (Venous Arterial blood Management Protection system [VAMP], Baxter Edwards Critical-Care, Irvine, CA; and Safe Draw, Ohmeda, Madison, WI) were chosen for comparison. After the normal 48 to 72 hrs of device use, the blood conservation systems were removed and semi-quantitative and quantitative cultures were taken from comparable sites of the two devices. Positive cultures from the patients were recorded and correlated with cultures obtained from the devices. In order to assess preference for either device, a survey tool was administered to the nursing staff who participated in the study. MEASUREMENTS AND MAIN RESULTS: Quantitative cultures from all sites cultured in both groups demonstrated mean colony counts of < 10(3) colony-forming units (cfu)/mL. There were no statistically significant differences in the colony counts at any of the sites compared between the two groups. There were no statistically significant relationships between positive cultures and patient age, gender, duration of device utilization, frequency of device entry, or the intensive care unit in which the study was conducted. In no circumstance did positive cultures from any of the blood conservation devices correlate with positive culture results from any sites of clinical infection. The clinical survey demonstrated a statistically significant preference for the VAMP system, which persisted despite increased experience with the Safe Draw system. CONCLUSIONS: The levels of microbial contamination noted in these devices were not consistent with clinical infection (defined as 10(3) cfu/mL on quantitative cultures). There was no significant difference in degree or pattern of contamination between the two devices. When utilized and changed according to the Centers for Disease Control guidelines, blood conservation devices are not harbors of infection in the critical care setting. Blood conservation devices can be used as part of a comprehensive blood conservation program in the critical care setting without undue concern for exacerbating infectious processes.

Blood Specimen Collection↗

PubMed1997

A retrospective analysis of microbial contaminants in outdated random-donor platelets from multiple sites.

BACKGROUND: Platelet components contaminated with bacteria are an important source of transfusion-associated bacterial sepsis. Estimates of contamination rates vary widely (0-10%) and are highly controversial. The present study, designed with stringent testing regimens, retrospectively determined the prevalence of microbial contaminants in platelets from four collection regions. STUDY DESIGN AND METHODS: During a 9-month period, outdated platelet units were assayed by spreading aliquots from the unit, and from thioglycollate broth medium inoculated with part of the unit, onto 5-percent sheep blood agar media. Cultures were examined after 72-hour incubation at 37 degrees C, and, if bacterial growth was present, the assay processes were repeated with fresh inocula. Units were considered contaminated only if repeatedly positive. RESULTS: Four (0.08%) of 4995 units sampled were contaminated, two with Corynebacterium sp. and one each with Propionibacterium acnes and Aspergillus terreus. Contaminants were present at low, subclinical levels and were detected only after amplification in thioglycollate. The contaminated units were cultured 1, 2, 3, and 7 days after expiration. CONCLUSION: Contamination rates were low and did not vary by region. The identification of A. terreus suggests the role that transfusion may play in transmitting fungal infections should be reassessed. The persistent detection of contaminated platelet units supports the need for a test to detect clinically relevant levels of microbial contaminants in blood components.

Aspergillus↗

PubMed1993

Use of disinfectants to reduce microbial contamination of hubs of vascular catheters.

The vascular catheter hub is a potential portal of entry for microorganisms that cause catheter-related sepsis. Thus, a reduction in catheter hub contamination might reduce the incidence of catheter-related sepsis. To develop a regimen suitable for reducing microbial contamination of the catheter hub, we experimentally contaminated catheter hubs and assessed the efficacies of disinfectant solutions. Catheter hubs were incubated overnight with suspensions of Staphylococcus epidermidis, Pseudomonas aeruginosa, or Candida parapsilosis. After removal of unattached microorganisms, the catheter hubs were swabbed by rotating cotton swabs dipped in 1% chlorhexidine, 1% chlorhexidine in 70% ethanol, 70% ethanol, 97% ethanol, or normal saline. Posttreatment swabs of the catheter hub were obtained and cultured quantitatively. The cleaning regimens containing ethanol were the most effective. Seventy percent ethanol was more effective than chlorhexidine and is likely to be the safest treatment. We conclude that cleaning of the catheter hub with disinfectant can dramatically reduce microbial contamination.

Catheterization, Peripheral↗

PubMedDate not supplied

Microbial contamination in allografted wound beds in patients with burns.

Microbial wound contamination has been recognized as a cause of autograft skin graft failure. Human cadaver allograft is believed to decrease or control microbial wound contamination, and by its adherence to the wound bed, to indicate a sufficiently low microbial count to allow successful application of autograft. Suboptimal "take" of more fragile cultured skin grafts after removal of adherent allograft led us to reexamine the microbial population of these wound beds. Immediately before autografts were placed, wound beds beneath adherent allograft were biopsied for quantitative microbiologic analysis. Eighty tissue biopsy specimens from 21 patients were examined. No patients had signs of infection or sepsis at the time of biopsy. Fifty-seven percent of all patients had positive cultures beneath adherent allograft skin. Twenty-one percent of all cultures revealed "infected" wound beds (greater than 100,000 colonies per gram), and 30% of all wounds were "colonized" (less than 100,000 colonies per gram). These data suggest that take and vascularization of allograft does not guarantee that a wound bed is free of microbial contamination.

Adolescent↗

PubMed1996

Microbial contamination of peripheral blood stem cell collections.

We prospectively evaluated microbiologic cultures for a series of 1263 peripheral blood stem cell harvests collected from 376 sequential patients. The incidence of microbial contamination was 0.23% of all samples, or 47% of samples from patients not receiving systemic antibiotics. This incidence of positive microbial cultures is less than that for cultures of bone marrow (3.8%) after harvesting and before further processing. Of the three positive cultures, two grew coagulase-negative Staphylococcus and the third, Streptococcus viridans. Two patients were reinfused with cultured-positive PBSC components, and neither exhibited the same organism in subsequent blood cultures. Although microbial contamination may occur during peripheral blood stem cell collection and cryopreservation, this report indicates that PBSC contamination does not play a conspicuous role in the infectious complications of PBSC transplantation.

Bacteriological Techniques↗

PubMed1994

Microbial contamination of cases used for storing contact lenses.

A survey of the hygienic practices of 178 contact lens wearers in west central Scotland was conducted along with assessment of microbial contamination of their lens storage cases. Multivariate analysis indicated that in some subgroups of lens wearers, the method of disinfection used, the use of unmodified tap water and the age of the lens, were significantly associated with microbial contamination of storage cases. In addition, statistical analysis suggested that features other than those commonly considered as important in contact lens hygiene, and therefore included in this study, may be more significant predictors of contamination of cases. Instruction of patients, patient compliance and simplicity of the regimen for the care of contact lenses may be important for achieving their safer use.

Adolescent↗

PubMed1982

Transplantation of microbially contaminated cadaver kidneys.

Bacterial cultures of graft perfusion fluid were taken on 514 renal perfusions during a ten-year period. A total of 22 positive cultures were found. Two sets of kidneys were discarded because of the bacteriology report. Only two possible wound infections were found that could be attributable to the preoperative contamination even though 19 of 24 patients with "contaminated" kidneys received no antibiotics. No loss of kidneys or life was found. Of the 22 contaminated perfusates, 18 (80%) originated from other institutions although only 144 (28%) of the total kidneys that were perfused came from other institutions. The majority of cultures indicated that the organisms were skin contaminants or organisms of low virulence. Microbial contamination of perfused cadaver kidneys is uncommon (1.2% in local kidneys and 9.3% in shared kidneys). Contaminated kidneys are not a major source of infection in renal transplant recipients. Kidneys that are contaminated with frequently virulent Gram-negative bacteria, such as Escherichia coli, should be discarded. Contamination of kidneys with Gram-positive organisms should not be a contraindication for transplantation, but the patients should probably be given prophylactic antibiotics.

Cadaver↗

PubMed1981

Efficacy of double-gloving as a barrier to microbial contamination during total joint arthroplasty.

UNLABELLED: After ten total hip replacements in which a double-glove technique was used, 275 outer and inner gloves were tested for microbial contamination and for holes. The operating rooms were equipped with specially designed air-filtration mechanisms. The results indicated that the gloves that most frequently were contaminated were the ones used exclusively for draping. This finding suggests that using a separate pair of outer gloves only for draping is a valuable technique during total hip replacement. CLINICAL RELEVANCE: Although the practice of using double gloves during a total joint-replacement procedure is accepted widely, there is little evidence that double-gloving actually decreases microbial contamination. The results of this study indicate that changing outer gloves at appropriate times during the procedure is indeed an important way to minimize contamination.

Antisepsis↗