Hepatitis C virus transmission in a Dutch haemodialysis unit: detailed outbreak investigation using NS5A gene sequencing

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

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.

Circulation of an atypical hepatitis C virus (HCV) strain at a dialysis unit in northeast India

Patients undergoing hemodialysis are at an increased risk of hepatitis C virus (HCV) infection. The implementation of standard infection control measures can substantially decrease the risk of infections and other nosocomial infections. To study the HCV infection rates and genotypes in maintenance hemodialysis subjects in a dialysis unit. A total of 196 maintenance hemodialysis subjects were tested for HCV RNA for one year at a tertiary care teaching hospital in northeast India continuously. Genotyping was performed using direct sequencing (Sanger sequencing) of the 5′UTR‐core region. The HCV infection rate was 26.0%. On phylogenetic analysis, 29 sequences clustered around genotype 3 and subtype 3f were observed. High sequence similarities (75–100% homology) were observed among the isolated sequences. High molecular similarities in the isolates from the same dialysis unit with a high infection rate (26.0%) over a relatively short period of study (10 months) indicated an ongoing nosocomial transmission. Nosocomial transmission by subtype 3f is rare, and it has not been reported in dialysis cases previously. The strain is most likely evolving from common strains such as 3b or 3i and may spread due to migration or movement of people. Urgent implementation of adequate infection control measures is required.

NS5A Gene Analysis by Next Generation Sequencing in HCV Nosocomial Transmission Clusters of HCV Genotype 1b Infected Patients

Background: The aim of the study was to investigate the intra-host variability through next-generation-sequencing (NGS) of the NS5A-gene in nosocomial transmission-clusters observed in two Italian hospitals among hepatitis C virus (HCV)-genotype-1b infected patients. Methods: HCV-sequencing was performed by Sanger-sequencing (NS3 + NS5A + NS5B) and by NGS (NS5A, MiSeq-Illumina) in 15 HCV-1b infected patients [five acute with onco-hematologic-disease and 10 (4/6 acute/chronic) with β-thalassemia]. Resistance-associated-substitutions (RAS) were analysed by Geno2pheno-algorithm. Nucleotide-sequence-variability (NSV, at 1%, 2%, 5%, 10% and 15% NGS-cutoffs) and Shannon entropy were estimated. Phylogenetic analysis was performed by Mega6-software and Bayesian-analysis. Results: Phylogenetic analysis showed five transmission-clusters: one involving four HCV-acute onco-hematologic-patients; one involving three HCV-chronic β-thalassemia-patients and three involving both HCV-acute and chronic β-thalassemia-patients. The NS5A-RAS Y93H was found in seven patients, distributed differently among chronic/acute patients involved in the same transmission-clusters, independently from the host-genetic IL-28-polymorphism. The intra-host NSV was higher in chronic-patients versus acute-patients, at all cutoffs analyzed (p < 0.05). Even though Shannon-entropy was higher in chronic-patients, significantly higher values were observed only in chronic β-thalassemia-patients versus acute β-thalassemia-patients (p = 0.01). Conclusions: In nosocomial HCV transmission-clusters, the intra-host HCV quasispecies divergence in patients with acute-infection was very low in comparison to that in chronic-infection. The NS5A-RAS Y93H was often transmitted and distributed differently within the same transmission-clusters, independently from the IL-28-polymorphism.