EnviroTest™
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How long should the EnviroTest be exposed to the air in a laminar flow hood, barrier isolator, clean room, and buffer room areas?
New USP guidelines suggest an exposure time of 1 hour in hoods and other areas. Exposing an EnviroTest longer than 1 hour in the air flow has the potential of drying the media. Is it most important to be consistent in the exposure duration.
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Moisture and water droplets occasionally appear on the inside of the EnviroTest tube. Does this have any effect on performance or shelf life?
Moisture on the inside of the tube does not harm the EnviroTest. This moisture comes from the agar on the EnviroTest paddles. Agar is mostly water and the atmosphere inside the tube stabilizes at 100% humidity.
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How should a pharmacist purposely contaminate an EnviroTest if they want to demonstrate microbial growth?
MInimizing touch contamination is a primary goal of aseptic technique testing. Pressing finger tips on the EnviroTest agar is an excellent way to inoculate the media. it also demonstrates how easily contamination can occur during a lapse in aseptic technique.
GroMed™
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Why are several repetitions of successful media transfers necessary to pass a validation or "competency test" of aseptic technique?
Multiple repetitions are necessary to simulate the most complex aseptic manipulations encountered during normal workloads. Many repetitions induce the boredom that can lead to lapses in good aseptic technique.
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Why is GroMed media offered in a variety of vials and bags?
Media transfer validations should simulate the actual manipulations typically encountering in a particular IV pharmacy. Examples include syringe transfers from vials to minibags, multiple additive procedures, syringe filling, and use of automated compounders. Multiple repetitive transfers from GroMed vials to GroMed minibags is an excellent example of a simulation of an actual procedure.
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How important is it to exactly follow the Directions for Use that come in each box of PATT and PATT2 kits?
The DFUs are written as suggestions only. They can be modified to more closely mimic the most difficult aseptic manipulations performed by a particular operator or pharmacy. For example, a pharmacy may add a high risk simulation of compounding a sterile injectable from a nonsterile ingredient to the end of the regular PATT test procedure. This could consist of placing a small quantity of a common, nonsterile powder like NaCl in a beaker. The operator adds non-sterile water to create a solution. The solution is drawn into a syringe, a sterile 0.22 micron filter with a sterile needle is attached to the syringe, and the liquid is injected into the TSB in the 100mL bag. The bag is observed for turbidity in the usual manner.
QuickTest™, QT Junior™, and QTMicro™ Systems
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If the IV admixture has already been infused into the patient by the time the QA Pharmacist knows the results from the contamination test, why bother?
Regular use of Q.I. Medical end-product testers is intended to confirm that aseptic technique is being maintained. Since it is impractical to test, quarantine, and then release every admixture, the supervising pharmacist must watch for trends in the contamination testing program. If several tests exhibit turbidity over a short period of time, it would trigger an investigation. An occasional positive would probably be tolerated. The supervisor would check to see if the occasional positives were prepared by the same pharmacist or technician. The point is to watch for trends and the detection of problems in validated procedures.
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How soon after mixing a sterile drug product should sterility testing begin?
An important study determined that sterility testing should begin within 40 to 60 minutes after preparation of intravenous admixtures. Testing that began after 60 minutes decreased the recovery of Staphylococcus epidermidis and lead to increased false negatives. Contact Q.I. Medical Technical Service to receive a free reprint of this research article.
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Why should the QuickTest be used with a compounder, pump, vacuum bottle, or vacuum bell when testing more than approximately 250mL of 3in1 TPN?
Commercial fat emulsions contain a substantial number of particles that are larger than 1 micron. These large particles can eventually occlude the QuickTest filter. Compounders and vacuum systems maintain a pressure difference across the filter. This pressure overcomes the resistance caused by the large fat particles.
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Doesn't the residual fat emulsion in the QuickTest cloud the TSB media and make seeing microbial-caused turbidity difficult?
Residual fat emulsion in the filter chamber would be a problem if we didn't have an effective two-step procedure for removing it. The bag of GroMed™ media that comes with each QuickTest contains approximately 20cc of air and 100mL of TSB. After filtering the admixture, the operator can perform an "air purge" of the filter chamber with the sterile air. This eliminates most of the residual fat emulsion. Then the filter is rinsed with 40 to 80mL of the sterile TSB. The last 20mL of TSB is left in the filter chamber to grow potential microbial contaminates.
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How frequently should a pharmacist test IV admixtures?
A typical sampling rate is 4% of the targeted IV admixtures. This means testing 1 out of every 25 admixtures. Some sampling plans approximate the 4% rate by testing a fixed amount each day or week. This sampling rate yields a 95% confidence level regarding the untested admixtures. For more details refer to: Morris, B.G., Avis, K.E., and Bowles, G.C., "Quality Control Plan for Intravenous Admixture Programs. II. Validation of Operator Technique", Am.J.Hosp.Pharm.37: 668 (1980).
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Can the QuickTest, QT Junior or QTMicro be used to detect microbial contamination in antibiotics?
Yes. The biggest concern is reducing the concentration of residual antibiotic agents in the tester's fluid path to a level where it does not interfere with culturing possible microbiological contaminates. USP suggests rinsing the filter sufficiently to remove these trace amounts of antibiotic agents.
QuickTest's and QT Junior's unique design of the filter helps the rinsing process. The filter membrane is held in the plastic support by insert molding. During manufacturing, molten plastic fills the microscopic pores around the filter's edges. Filling these pores prevents residual traces of antibiotics from being trapped in the filter's edge during rinsing.
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Which sterility test products meet the USP's definition of "Membrane Filtration", described as the method of choice in chapter <797>?
The QuickTest, QT Junior, and QTMicro are "Membrane Filtration" sterility test devices. Examples of the second choice for sterility testing, "Direct Inoculation of the Culture Medium", are the TuffTest and GroMed products.
TuffTest™
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What is the purpose of the TuffTest?
TuffTest detects microbial contamination in sterile small volume admixtures that are suspensions or emulsions. Suspensions and emulsions are naturally turbid. That prevents visualizing microbial growth in the liquid media. TuffTest reduces this problem by having sterile agar paddles inside the bottle of media, separate from the liquid media, on which growth can be observed.
Potato Dextrose Agar (PDA) Slant
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What is the purpose of the PDA slant tubes?
The Potato Dextrose agar is recommended for the secondary cultivation of fungi and inducement of sporulation. Some slow growing fungi prefer a surface on which to grow and can be difficult to detect in liquid media. The agar and growing conditions are designed to maximize the opportunity to detect fungal contamination that may otherwise go undetected in liquid media.
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How are PDA slant tubes used as part of a sterile drug products QA program?
"Secondary cultivation" means that after a QTMicro, QT Junior, QuickTest, TuffTest, or GroMed container has completed it's observation period, up to 1mL of TSB from the tester is transferred to the PDA tube for further observation. The agar is inspected for not less than 14 additional days.
GroMed 10mL Tubes
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What is the purpose of the 10ml tubes of TSB (#GM0100) if the preferred method of testing for sterility in compounded medications is "full filtration".
Some drugs are dispensed in containers where it is difficult to transfer the contents through a filter test device. Respiratory drugs and eye drops are good examples. These drugs can be carefully transferred into the 10mL tubes by removing and replacing the screw cap. Some viscous drugs cannot be filtered using a 0.22 micron membrane. They can be injected directly into the TSB media via the needle access port on the top of the screw cap.
PyroTest™
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What is the purpose of the PyroTest?
PyroTest kits provide pharmacists with a quick, inexpensive method of testing extemporaneously compounded drugs for excessive endotoxins.
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How long does it take to get results from the PyroTest kit?
Sample preparation requires less than a minute. Incubation time is exactly 1 hour.
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What compounded drugs should be tested for bacterial endotoxins?
Any drug prepared from nonsterile drug components or from an intermediate compounded from a nonsterile component should be tested for endotoxin. Refer to USP Chapter <797> for more details. Some admixtures are incompatible with the LAL gel clot test method. Chemicals with known interference problems include acids, alcohols, phenols, chelators, surfactants, and some antibiotics. Normal dilution of the test sample may overcome minor interference problems. Each PyroTest kit includes a Positive Control to alert the pharmacist to interference from something in the test sample, vibration during incubation, or incorrect incubation time or temperature.
Incubation of Samples
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Which Q.I. Medical products require incubation at other than room temperature, 20 to 25°C?
The PyroTest is the only test that requires incubation at an elevated temperature. GroMed liquid media may yield faster results at elevated temperatures but incubation is not needed for consistent, reliable results. Refer to USP Chapter <797> for more details.
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How long do samples have to remain in the incubator in order to yield reliable results?
According to USP <797> the EnviroTest should be incubated at 30 to 35°C and observed not less than 48 hours. An alternative method is to incubate at 20 to 25°C and observe for not less than 96 hours.
USP recommends incubating sterility tests using Soybean-Casein Digest Medium (TSB), like the TuffTest, QuickTest, QT JUnior, QTMicro, and all GroMed units, at 22.5°C +/- 2.5°C. They should be examined at 48 hours and daily thereafter. Positives should be removed immediately. Units not showing growth should remain in the incubator for not less than 14 days.
Potato Dextrose Agar slants are incubated upright, out of direct light, at 15 to 30°C for 7 to 14 days.
PyroTest vials are incubated at 37°C +/- 1°C and checked for firm gels at 60 minutes.
Testing 70% Isopropyl Alcohol (IPA)
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Which Q.I. Medical products are appropriate for periodically testing sanitizing agents like IPA for microbial contamination as described in USP chapter <797>?
One inexpensive and convenient method of testing bulk supplies of IPA for microbial contamination is to introduce an aliquot of the sanitizing agent directly into TSB media like the GroMed #GM0100 tube or #GM0200 vial. Observe for growth for not less than 14 days.
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