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According to a recent study on the risk of hepatitis C transmission through multidose medication vials, which of the following statements is MOST likely true? Read the discussion.
(A) Hepatitis C can be transmitted to a patient only if the needle being used to draw the medication, not the rubber access diaphragm of the medication vial, was contaminated with the virus.
(B) The use of 70% isopropyl alcohol to wipe the rubber access diaphragm of a used multidose vial prevented transmission of hepatitis C into the vial.
(C) The hepatitis C virus can live in the liquid medication of a multidose vial for 72 hours.
(D) The use of a sterile needle and syringe to draw medication from a contaminated multidose vial prevented transmission of the virus.
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Discussion
Infection associated with the use of multidose vials has been a topic of research for many years. There have been reports of nosocomial hepatitis C outbreaks from suspected contamination of multidose vials even though practitioners denied the reuse of a needle or syringe when drawing medications. Studies have cited unsafe injection practices, poor sanitation practices, or contaminated medical equipment as possible reasons for nosocomial hepatitis C infections. A recent study used in vitro methods to find a possible mechanism for hepatitis C contamination of multidose medication vials.
The authors used cell culture–derived hepatitis C viral droplets placed onto the rubber access diaphragm of medication vials. This was used to simulate a health care setting that uses multidose vials to determine whether the vial’s diaphragm can be contaminated by a practitioner who is handling the vial while treating a patient with hepatitis C. The viral droplets were then allowed to dry on the diaphragm surface. Each diaphragm was penetrated 5 times using a sterile syringe and a sterile blunt-tip needle. One vial contained cell culture medium and the medication vials contained 1 of these 6 liquids:
The liquid in the vial was introduced into a cultured cell medium. Positive controls used the cell culture medium exposed to 33 µL of active hepatitis C virus whereas the negative controls used defective viral stock. The medication vials were examined individually for hepatitis C virus stability and viability. Assessment of contamination was performed for each sample. A positive response was the presence of at least 3 hepatitis C viral foci. The results showed that even though a sterile needle and syringe were used, the medication in the vial became contaminated as the needle pierced through the contaminated rubber diaphragm. A contaminated needle need not be the source of infection. The authors reported that the hepatitis C virus remained stable and infectious in all medications tested for 72 hours both by unit assay and quantitative reverse transcription-polymerase chain reaction analysis (Figure 1). This was true regardless of the use of preservatives or antimicrobial additives to the medication.
Figure 1. Hepatitis C virus (HCV) remains stable in all medications tested for at least 72 hours. High-titer (3.27 × 105 focus-forming unit/mL) HCV stock was diluted in dexamethasone (A), lidocaine (B), neostigmine (C), phenylephrine and vehicle (saline) (D), propofol (E), rocuronium (F), or cell culture medium. At the indicated time points, contaminated medications were further diluted in cell culture medium and plated on Huh-7.5 cells. HCV genome copies were assessed by quantitative real-time reverse transcription–polymerase chain reaction analysis at 5 days postinfection. All data are representative of 3 independent experiments, and error bars represent SD. Used with permission, from van Vlymen JM, Magnus J, Jaeger M, et al. Hepatitis C contamination of medication vials accessed with sterile needles and syringes. Anesthesiology. 2019;131(2):305-314. doi:10.1097/ALN.0000000000002772
To evaluate the impact of using 70% isopropyl alcohol disinfection, the rubber diaphragms of the medication vials were contaminated with hepatitis C virus stock and then cleaned with alcohol wipes. When wiping the diaphragms, friction was used. The method was applied 3 ways: single wipe, 2- to 3-second wipe, and 10-second wipe. The authors also evaluated the cleansing of the diaphragm with and without drying of the alcohol. The diaphragms were then rehydrated with 2 mL of cell culture medium for 1 hour. This medium was then placed in cells to evaluate viral growth. The results showed neither a single nor a 2- to 3-second wipe was adequate to eliminate hepatitis C viral infectivity. The 10-second wipe reduced the risk of contamination in most vials, but was not enough to completely eliminate hepatitis C viral infectivity in all vials. Interestingly, the US Centers for Disease Control and Prevention, the American Society of Anesthesiologists, and the Provincial Infectious Diseases Advisory Committee of Ontario all recommend the 10-second wipe with friction as the cleaning protocol for multidose vials to prevent the spread of infection from patient to patient.
The conclusion of the authors was that the only absolute way to prevent the spread of hepatitis C when administering medications to patients is either to have the pharmacy prepare single-dose syringes from multidose vials using aseptic technique or for manufacture and use of multidose vials to be eliminated.
In summary, the risk of hepatitis C virus transmission through contaminated multidose vials is real, and conventional disinfection methods do not eliminate the risk.
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