An outbreak of hepatitis C virus attributed to the use of multi-dose vials at a colonoscopy clinic, Waterloo Region, Ontario

Abstract

Background: Hepatitis C virus (HCV) transmission has been epidemiologically linked to healthcare settings, particularly out-of-hospital settings such as endoscopy clinics and hemodialysis clinics. These have been largely attributed to lapses in infection prevention and control practices (IPAC).

Objective: To describe the public health response to an outbreak of HCV that was detected among patients of a colonoscopy clinic in Ontario, and to highlight the risks of using multi-dose vials and the need for improved IPAC practices in out-of-hospital settings.

Methods: Screening for HCV was conducted on patients and staff who attended or worked at the clinic within the same timeframe as the index case's procedure. Blood samples from positive cases underwent viral sequencing. Inspections of the clinic assessed IPAC practices, and a chart review was done to identify plausible mechanisms for transmission.

Outcome: A total of 38% of patients who underwent procedures at the clinic on the same day as the index case tested positive for HCV. Genetic sequencing showed a high degree of similarity in the HCV genetic sequence among the samples positive for HCV. Chart review and clinic inspection identified use of multi-dose vials of anesthesia medication across multiple patients as the plausible mechanism for transmission.

Conclusion: Healthcare workers, especially those in out-of-hospital procedural/surgical premises, should be vigilant in following IPAC best practices, including those related to the use of multi-dose vials, to prevent the transmission of bloodborne infections in healthcare settings.

Keywords: HCV; IPAC; contamination; infection prevention and control practices; out-of-hospital healthcare settings; outbreak.

Figure 1

Phylogenetic analysis of Sanger population-based sequencing of HCV E1/NS5B subgenomic regions from five patients in an outbreak investigation^a Abbreviation: HCV, hepatitis C virus ^a Neighbour-joining tree was created by using Kimura’s two-parameter model in MEGA software version 6. Outbreak sequences from this outbreak (W) and two other similar outbreaks in endoscopy clinics from Toronto (T1 and T2) are in red, green and blue boxes, respectively. Epidemiologically unrelated HCV sequences from the province of Ontario collected in the same year (2013) as well as some randomly selected sequences from GenBank are in black. The dendrogram in Fig. 1A is based on E1 region and that in Fig. 1B is based on the NS5B region. Note that phylogenetic analysis based on NS5B region did not have the same strong bootstrap support as that observed for E1 region. In comparison the bootstrap measures for the two other similar outbreaks T1 and T2 remained robust for both the E1 and NS5b although dropped somewhat from 98 to 84 for T1

Figure 2

Phylogenetic analysis of HCV HVR-1 quasispecies in samples of five patients involved in a transmission event in this outbreak (outbreak W)^a Abbreviation: HCV, hepatitis C virus ^a Sequences of HCV genotype 1b quasispecies population derived from three different outbreaks (T1, T2 and W), sequences of unrelated HCV strains from Ontario and GenBank (green triangles) and randomly selected HCV strains from GenBank (purple squares) are shown on the left side of the figure. Bootstrap values are shown at the bottom of the nodes. Sequences of the five cases from outbreak W are colour-coded and magnified on the right corner of the figure. Each colour dot (node) represents a single HCV variant. Quasispecies of patient #6 (transmission source) green; patient #7 red; patient #8 pink; patient #10 blue; patient #13 yellow. Note that consensus sequences from the unrelated HCV strains from Ontario and GenBank, as well as the quasispecies from two other HCV outbreaks T1 and T2 occupy entirely different sequence space