Infection Control & Hospital Epidemiology
contaminated surfaces. The dipping of 5mm of the tip of a rubber sleevepickedup0.06μL(mean±SD, 0.02μL) of the HCV-positive plasma. This volume was so low thatthisinoculumwas invisibleto the naked eye and was less than the 1.4μL(mean volume)inoculum from a hollow-needle needlestick injury.11 Therefore, this procedure was a reasonable substitute for in vitro simulation. The objective of the 2 radionuclide experiments was to dynamically investigate the possibility of reflux communication from RBCTH into the patient during a simulated phlebotomy (not virus transmission). A reflux can only happen in 2 condi- tions: bidirectional patency and pressure difference. Blood has both solution and colloidal properties; therefore, it is a homo- geneous carrier medium for transport of all its normal con- stituents (from cells to molecules). Ideally, 99mTc-labeled blood (eg, used for study of gastrointestinal bleeding) could be used for this experiment. In addition, a 16G–20G needle has an inner cross-sectional area 7,000–27,000 times that of red blood cells, which is thus statistically and obviously not a limiting factor for the size of a molecule or virus. The pressure change created by releasing the manual pressure from the saline bag was unquan- tified (please note that we did not say negative pressure). How- ever, during phlebotomy, differential pressure changes are known to be operator and patient dependent; therefore, they vary and, likewise, were unquantified. Our experiment clearly demonstrated that even a very gentle manually applied dynamic pressure dif- ference on the saline bag could induce a patent route of reflux from the needle side to the bag side during the simulation of phlebotomy with RBCTH. Regarding the backflow of blood, the crux of the matter is the
sudden release of the tourniquet, which allows the venous blood under positive pressure below the tourniquet (at antecubital fossa level) to go above the tourniquet at arm level. The HCV- contaminated “blood pool” between sleeved-needle and the sleeve then flows back into the patient. Thus, creating negative pressure in the venous system is unnecessary for causing the backflow. As long as there is a pressure gradient between the vein below and above the tourniquet, the HCV-contaminated blood can flow into the patient when the tourniquet is released. We did not find any peer-reviewed journal, publication-quality
methodology or data in reference 5 cited by Tsang et al. This citation refers to the evaluation of a single-use tube holder and the low risk of backflow from the vacuum specimen container through the sleeved needle back into the patient, whereas our study refers to RBCTH and the risk of backflow from the blood pool between the sleeve and the sleeve needle (not the vacuum specimen tube) into the patient. Both our testing with HCV-positive plasma (with virions much bigger than technetium) and radioactive technetium (visible on radiation scanning) showed significant backflow into the patient’s side, therefore posing a risk to the patient. Most impor- tantly, our phlebotomists have not been trained to comply with the manufacturer’s instruction of the need to release the tourniquet once the blood starts to flow into the vacuum specimen tube. Without providing evidence that the blood inside the tube
holder belonged to the patient’s own blood and not the source patient, the opinion of Tsang et al is speculative. We showed that the genetic sequences from the source, the RBCTH, and the victim were 99.54% identical. We believe that the evidence presented in our original article
and our present rebuttals are scientifically well grounded, con- trary to the description by Tsang et al as “exaggerated, flawed, superfluous, hasty, premature or disproportionate.” Our data were scrutinized by the Hospital Authority governing all public
253
hospitals in Hong Kong. The Hospital Authority terminated the further use of RBCTH to protect patients. We now follow the best practice in the United States, United Kingdom, and Australia of using only disposable single-use tube holders. If RBCTH are ever used, the phlebotomist must comply with the manufacturers’ instructions by disinfecting all RBCTH between patients and by releasing the tourniquet once blood starts to flow into the spe- cimen containers. Unfortunately, these important instructions have not been provided to frontline healthcare workers for many years; thus, more cases presenting with HCV cirrhosis and hepatocellular carcinoma may be expected over time.
Acknowledgments. None.
Financial support. This work was supported in part by the donations of Mr. Michael Tong, Providence Foundation (in memory of the late LuiHac Minh) and the Hong Kong Hainan Commercial Association and by funding from the Consultancy Service for Enhancing Laboratory Surveillance of Emerging Infectious Diseases of the Department of Health, Hong Kong Special Administrative Region, and the Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, the Ministry of Education of China.
Conflicts of interest. All authors declared no potential conflicts of interest.
Supplementary material. To view supplementary material for this article, please visit
https://doi.org/10.1017/ice.2018.314
References
1. Tsang DNC, Ip M, Chan PKS, et al. Are reusable blood collection tube holders the culprit for nosocomial hepatitis C virus transmission? Infect Control Hosp Epidemiol 2018;X:X–X.
2. BD vacutainer eclipse blood collection needle. Becton Dickinson website.
https://www.bd.com/documents/bd-legacy/quick-guide/blood-and-urine- collection/PAS_BC-BD-Eclipse-Blood-Collection-Needle-Points-to-Practice_ QG_EN.pdf. Accessed October 23, 2018.
3. VACUETTE blood collection tubes. Evacuated blood collection system for in vitro diagnostic use. Greiner Bio-One website.
https://www.gbo.com/ fileadmin/user_upload/Downloads/IFU_Instructions_for_Use/IFU_ Instructions_for_Use_Preanalytics/English/980200_EN_rev20.PDF. Accessed October 23, 2018.
4. VACUETTE blood collection techniques. Greiner Bio-One website.
https://www.gbo.com/fileadmin/user_upload/Downloads/Brochures/ Brochures_Preanalytics/English/980063_BloodCollectionTechnique- s_e_rev07_0116_lowres.pdf. Accessed October 23, 2018.
5. Campo DS, Xia GL, Dimitrova Z, et al. Accurate genetic detection of hepatitis C virus transmissions in outbreak settings. JInfectDis 2016;213:957–965.
6. Widell A, Christensson B, Wiebe T, et al. Epidemiologic and molecular investigation of outbreaks of hepatitis C virus infection on a pediatric oncology service. Ann Intern Med 1999;130:130–134.
7. Grethe S, Gemsa F, Monazahian M, Böhme I, Uy A, Thomssen R. Molecular epidemiology of an outbreak of HCV in a hemodialysis unit: direct sequencing of HCV-HVR1 as an appropriate tool for phylogenetic analysis. J Med Virol 2000;60:152–158.
8. Garvey MI, Bradley CW, Holden KL, et al. Use of genome sequencing to identify hepatitis C virus transmission in a renal healthcare setting. J Hosp Infect 2017;96:157–162.
9. Girou E, Chevaliez S, Challine D, et al. Determinant roles of environmental contamination and noncompliance with standard precau- tions in the risk of hepatitis C virus transmission in a hemodialysis unit. Clin Infect Dis 2008;47:627–633.
10. Calles DL, CollierMG, Khudyakov Y, et al. North Dakota Hepatitis C Virus Investigation Team. Hepatitis C virus transmission in a skilled nursing facility, North Dakota, 2013. Am J Infect Control 2017;45:126–132.
11. Napoli VM, McGowan JE Jr. How much blood is in a needlestick? J Infect Dis 1987;155:828.
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