Infection Control & Hospital Epidemiology (2019), 40, 250–251 doi:10.1017/ice.2018.302


Letter to the Editor


Are reusable blood collection tube holders the culprit for nosocomial hepatitis C virus transmission?


Dominic N. C. Tsang FRCPath1, Margaret Ip FRCPath2, Paul K. S. Chan MD2, Patricia Tai Yin Ching CPHQ3, Hung Suet Lam MPH4 and Wing Hong Seto FRCPath3 1Department of Pathology, Queen Elizabeth Hospital, Hong Kong Special Administrative Region, China, 2Department of Microbiology, The Chinese University of


Hong Kong, Hong Kong Special Administrative Region, China, 3WHO Collaborating Center for Infectious Disease Epidemiology and Control, The University of Hong Kong, Hong Kong Special Administrative Region, China and 4Hong Kong Infection Control Nurses’ Association, Hong Kong Special Administrative Region, China


To the Editor—Cheng et al1 published an interesting report of a case of nosocomial transmission of hepatitis C virus with a reu- sable blood-collection tube holder postulated as the vehicle for transmission. Healthcare-associated hepatitis C virus transmis- sion has been most often related to breakdown of infection control practices such as poor hand hygiene, use of contaminated gloves or equipment, and practices such as syringe reuse con- taminating multiple-dose vials of infusions.2–4 In their report, investigations were performed to identify the source of trans- mission. However, their investigations were associated with flaws and were performed disproportionately. First of all, the authors arguably excluded the possibility of


lapses in infection control measures simply by direct observation. It is inconceivable to rule out such an important aspect solely by direct observation after the incident has just occurred, which is inevitably confounded by the Hawthorne effect. Second, the authors stated that by reviewing the time log in


the barcoding system of the computerized laboratory informa- tion system, they identified 14 instances of phlebotomy from the source patient followed by the index patient. However, they did not mention that many phlebotomists were involved, all using their own blood collection sets. Also, there was clearly no instance of one phlebotomist taking blood from the source patient that immediately followed the index patient. Further- more, the 2 patients in this episode were different genders. The practice of the affected unit is to have 2 phlebotomists working together, one serving male patients and the other serving female patients. The chance of transmission from the male (source) patient to the female (index) patient via contaminated tube holder is remote. Third, for the environmental surveillance specimens collected


for the presence of HCV, 28 of 34 environmental samples were collected from tube holders. Only 1 was obtained from the glucometer tray; 3 were obtained from the tray for phlebotomy; and 2 were obtained from the phlebotomy trolley. Thus, the focus on this environmental surveillance is too narrow and not global


Author for correspondence: Dominic N. C. Tsang, Department of Pathology, Queen


Elizabeth Hospital, 30 Gascoigne Road, Kowloon, Hong Kong Special Administrative Region, China. E-mail: nctsang@ha.org.hk


Cite this article: Tsang DNC, et al. (2019). Are reusable blood collection tube holders


the culprit for nosocomial hepatitis C virus transmission? Infection Control & Hospital Epidemiology 2019, 40, 250–251. doi: 10.1017/ice.2018.302


© 2019 by The Society for Healthcare Epidemiology of America. All rights reserved.


enough to identify other possibilities. The authors’ claim of reu- sable tube holders being the only shared items cannot be sub- stantiated before a complete workup has been done. Notably, investigations concerning peripheral and central intravenous catheter insertion as well as intravenous injections of medication including the use of multiple-dose vials were missing. The authors reported that HCV was found in the inner side of a single tube holder. But the date of surveillance sampling was not stated and was likely to have been performed months after the HCV trans- mission has occurred, and we have no affirmation regarding whether this tube holder, of the 14 tube holders sampled, had been used by both the source and index patient. Surely, the likelihood is that the tube holder was in fact entirely used for and contaminated by the index patient. All of these items provide precise circumstantial evidence to


refute the postulation. As such, molecular genetic study is superfluous and if done, whole-genome sequencing of HCV iso- lates would have been the preferred method. We are also unconvinced of the validity of the in vitro experiments. In the simulated phlebotomy experiment, the 5-mm tip of the rubber sleeve capping the sleeved-needle was dipped into HCV-containing plasma to deliberate contaminate the inner wall of tube holder. This is exaggerated and unlikely to happen in real life. Using HCV-negative EDTA blood at atmospheric pressure to mimic the venous side of a patient is also incorrect because venous pressure at cubital fossa remains positive during venesection. Moreover, the risk of return flow had been vigor- ously investigated. Even in the most extreme scenario, where the temperature inside blood collection tube (blood plus air) reaches 37°C, combined with an eccentric penetration of cap, the max- imal return flow volume is still less than the dead volume of smallest needle; therefore, no back flow occurs.5 For the radionucleotide study, the tip of the sleeve needle,


instead of the rubber sleeve, was smeared with gauze containing a few drops of 99mTcO4. 99mTcO4 is a very small molecule, with a molecular weight of only 30×10−5 attograms. If we assume that HCV has a density similar to water, each HCV weighs ~21.6 attograms (given a 60-nm size). Comparing a molecule with a particle is a very inappropriate analogy. Furthermore, the negative pressure created by releasing the manual pressure from the saline bag to simulate the suction of virus into the blood- stream was unquantified. In the next experiment, the authors


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