Year : 2009 | Volume
: 6 | Issue : 1 | Page : 110--115
Hepatitis B virus transmission and reprocessing of endoscopes
Amit Kumar Dutta, Ashok Chacko
Department of Gastrointestinal Sciences, Christian Medical College and Hospital, Vellore - 632 004, India
Department of Gastrointestinal Sciences, Christian Medical College and Hospital, Vellore
Hepatitis B virus (HBV) cross-infection during endoscopy is rare. Most of the reported cases have occurred when the endoscope reprocessing was inadequate. Standard reprocessing of endoscopes and accessories is sufficient to prevent HBV transmission.
|How to cite this article:|
Dutta AK, Chacko A. Hepatitis B virus transmission and reprocessing of endoscopes.Hep B Annual 2009;6:110-115
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Dutta AK, Chacko A. Hepatitis B virus transmission and reprocessing of endoscopes. Hep B Annual [serial online] 2009 [cited 2020 Feb 24 ];6:110-115
Available from: http://www.hepatitisbannual.org/text.asp?2009/6/1/110/76908
Rapid technological advances have widened the array of diagnostic and therapeutic procedures performed endoscopically. As a result, the number of endoscopies performed is increasing and along with it the potential for complications.  Transmission of infection is an important concern as the surfaces and channels of endoscopes are exposed to body fluids and blood during endoscopy.  Meticulous cleaning and disinfection of endoscopes and accessories are critical in preventing cross-infection.  Multiple societies have laid down guidelines for disinfection of endoscopes and accessories. ,4 Infectious complications resulting from endoscopy are rare, with an estimated incidence of one in 1.8 million procedures, reported in the early nineties.  Since the introduction of appropriate disinfection guidelines, the estimated incidence has further declined to one in 10 million.  Evidence shows that most instances of transmission of infection, during endoscopy, results from the failure to adhere to proper disinfection guidelines. ,, Infectious agents reported to be transmitted during endoscopies include bacteria (Pseudomonas, Salmonella, H. pylori) and viruses (HCV, HBV).  This chapter focuses on the evidence of HBV transmission attributed to endoscopy and methods of prevention.
HBV Transmission Attributed to Endoscopy
Transmission of HBV attributable to endoscopy is extremely rare. , Multiple prospective studies on patients undergoing endoscopies, with instruments previously used on HBV-infected patients, have failed to show evidence of infection during the follow up-period. ,11],, A case control study by Villa and colleagues did not find any causal relationship between endoscopy and HBV infection.  In fact only five cases of HBV transmission related to endoscopy have been reported and none so far in this century.  Nelson et al., in their review, have suggested that in three of these five cases the reprocessing was inadequate. ,,, In the other two reports, the association with endoscopy was not properly established. , Surveys from India and the rest of the Asia-Pacific regions have revealed that disinfection procedures for endoscopes and accessories were inadequate in many centers. , This is a matter of serious concern as it provides the opportunity for transmission of infection.
Endoscope Reprocessing and Prevention of HBV Transmission
Infection transmission during endoscopy may be exogenous (patient to patient or health care worker to patient or patient to health care worker) or endogenous (spread of infection from the mucosal surface to the blood stream and distant sites).  HBV transmission is exogenous. For successful transmission, the chain of infection has to be intact. This includes a viable virus present on the mucosal surface / blood / secretions in sufficient quantities, which should be carried by a suitable vehicle to a susceptible host at an appropriate portal of entry.  The best way to break this chain of infection is by eliminating the virus from the vehicle of transmission (endoscopes and accessories) by proper reprocessing.
There are no special reprocessing guidelines for endoscopes and accessories, to prevent HBV cross-infection. Standard reprocessing is sufficient to eliminate them. , This is advantageous as the HBV infection status is usually unknown in many patients at the time of endoscopy. In a study from Japan, samples were obtained by flushing water in the endoscope channel after cleaning it with an enzyme / detergent and again after reprocessing with a disinfectant.  In the samples obtained from endoscopes used for HBV infected patients (n = 17), reverse transcriptase polymerase chain reaction (RT-PCR) for HBV DNA was performed in all, and five were positive for HBV DNA at the end of cleaning, but none after reprocessing. An animal model study on HBV transmission via invasive equipment showed that disinfection alone may not eliminate viral transmission and adequate cleaning prior to disinfection is essential.  The studies show that proper cleaning followed by disinfection is the key to prevent HBV transmission.
The reprocessing guidelines differ according to the device used. The classification proposed by Spaulding divides the medical devices into critical and semi-critical, based on the risk of infection with their use.  A device that comes into contact with the mucous membrane, but does not penetrate the sterile tissue is classified as semi-critical. The fibreoptic endoscope comes under this category. These devices have a moderate risk of infection transmission and require a high-level of disinfection (destruction of all vegetative microorganisms, mycobacteria, viruses, fungal spores, and some, but not all, bacterial spores) before reuse.  The steps of reprocessing include:
Cleaning the endoscope and its detachable components using a detergent solution and brushesHigh level of disinfection using a liquid chemical germicide (e.g., 2% glutaraldehyde for ten minutes)Drying the instrument ,
A device that penetrates the skin, mucosa, body cavity or vascular space is classified as critical. This includes needles, biopsy forceps, sphincterotomes, and so on. Generally these devices are labeled as single use, but financial constraints may necessitate their reuse. A critical device has a high risk of transmitting infection and requires sterilization (destruction of all microbial life) before reuse.  The device should be thoroughly cleaned using enzymes, brushes, and detergent solutions. Sterilization may be done by autoclaving with steam at 134ºC for 18 minutes. Gas sterilization by using ethylene oxide or plasma is also effective. Apart from using the standard reprocessing techniques, adequate training of staff and quality control measures are also essential in preventing and monitoring infection transmission. 
In conclusion, HBV transmission during endoscopy is rare. Current disinfection guidelines, if followed properly, are sufficient to eliminate the risk of hepatitis B transmission.
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