Evaluation of the Xpert HCV VL Fingerstick point-of-care assay and dried blood spot HCV-RNA testing as simplified diagnostic strategies among people who inject drugs in Catalonia, Spain.

BACKGROUND: Catalonia requires decentralized and simplified strategies for the diagnosis of viremic HCV infection among people who inject drugs (PWID). We aimed to perform a direct comparison of the diagnostic performance between two, single-step strategies for the screening and diagnosis of viremic HCV infection in PWID attending a drug consumption room (DCR) in Barcelona: i) on-site HCV-RNA testing using the point-of-care test (PoCT) Xpert HCV VL Fingerstick; and ii) on-site dried blood spots (DBS) collection for HCV-RNA testing at the laboratory (in-house assay). Additionally, we aimed to assess participants' preferences in receiving HCV-RNA testing results and feasibility of same-day delivery of PoCT results. METHODS: The real-world, clinical performance of these two strategies was established in comparison with the reference method (HCV viral load testing with the Xpert HCV Viral Load assay at the laboratory from venous plasma collected at the DCR). HCV genotypes/subtypes and HIV status were also determined by sequencing and serology, respectively. A questionnaire including preferences regarding the delivery of test results was administered. RESULTS: The prevalence of HCV-RNA was 63.0% (of which 25.8% were co-infected with HIV). The RNA-PoCT showed a sensitivity of 98.4% for detectable viral loads (>4 IU/mL) and of 100% for quantifiable viral loads (≥10, ≥1000 and ≥3000 IU/mL). For the DBS-based assay, a sensitivity of 93.7% was obtained for detectable viral loads, 96.7% for the quantifiable ≥10 IU/mL threshold, and 98.3% for both the quantifiable ≥1000 and ≥3000 IU/mL thresholds. No significant differences were detected between the sensitivity values of these two strategies, and the specificity was 100% in both cases. Half of the participants preferred to receive the HCV-RNA result on the same day, and 80% of participants received their RNA-PoCT results on the same day. CONCLUSIONS: Both the HCV-RNA PoCT and the DBS-based assay are highly reliable tools for the simplified diagnosis of viremic HCV infection among current PWID. These strategies allow for on-site sample collection and delivery of test results, facilitating decentralized care in harm reduction services.

Reliable resolution of ambiguous hepatitis C virus genotype 1 results with the Abbott HCV Genotype Plus RUO assay.

Accurate subtyping of hepatitis C virus genotype 1 (HCV-1) remains clinically and epidemiologically relevant. The Abbott HCV Genotype Plus RUO (GT Plus) assay, targeting the core region, was evaluated as a reflex test to resolve ambiguous HCV-1 results in a challenging sample collection. 198 HCV-1 specimens were analysed with GT Plus (38 specimens with and 160 without subtype assigned by the Abbott RealTime Genotype II (GT II) assay targeting the 5'NC and NS5B regions). Sanger sequencing of the core and/or NS5B regions were performed in 127 specimens without subtype assignment by GT II, with "not detected" results by GT Plus, or with mixed genotypes/subtypes. The remaining GT Plus results were compared to LiPA 2.0 (n = 45) or just to GT II results if concordant (n = 26). GT Plus successfully assigned the subtype in 142/160 (88.8%) samples. "Not detected" results indicated other HCV-1 subtypes/genotypes or mismatches in the core region in subtype 1b. The subtyping concordance between GT Plus and either sequencing or LiPA was 98.6% (140/142). Therefore, combined use of GT II and GT Plus assays represents a reliable and simple approach which considerably reduced the number of ambiguous HCV-1 results and enabled a successful subtyping of 98.9% of all HCV-1 samples.

Community-based screening of hepatitis C with a one-step RNA detection algorithm from dried-blood spots: Analysis of key populations in Barcelona, Spain.

Alternative strategies are required to enhance the diagnosis of silent hepatitis C virus (HCV) infections in key populations at risk. Among them, HCV prevalence and bio-behavioural data are scarce for HIV-negative men who have sex with men (MSM) and men and trans-women sex workers. We sought to describe and assess the potential benefits of a community-based one-step HCV screening and confirmatory strategy for these populations in Barcelona. The screening strategy based on a real-time RT-PCR assay for HCV-RNA detection in dried-blood spots (DBS) was validated and implemented in addition to an antibody point-of-care test in a community centre. HCV prevalence was assessed, and bio-behavioural data were collected. The molecular assay was precise, reproducible, sensitive and specific. Four HIV-negative MSM reported being currently infected (0.75% HCV self-reported prevalence). Implementation of DBS testing was easy, and acceptability was >95%, but no silent HCV case was diagnosed (N = 580). High-risk sexual practices and drug use for sex were reported frequently. HIV prevalence was 4.7% in MSM and 10% in sex workers. Self-reported prevalence of other STIs ranged from 11.3% to 36.2%. In conclusion, HCV-RNA testing in DBS showed a good performance, but the assessed one-step strategy does not seem beneficial in this setting. Although no silent HCV infections were detected, the observed high-risk behaviours and prevalence of other STIs suggest that HCV spread should be periodically monitored among these populations in Barcelona by means of behavioural surveillance, rapid antibody testing and molecular confirmation in DBS.

Epidemiological features and determinants for Chlamydia trachomatis infection among women in Catalonia, Spain.

We determined the prevalence of Chlamydia trachomatis (CT) infection and risk factors for its acquisition by women aged less than 35 years who were attending sexual health centres in the province of Barcelona in 2007. A convenience sample of 397 adolescents and young adult women aged between 16 and 35 years, stratified by age and recruitment site, were tested using realtime polymerase chain reaction by CT DNA. A standardized questionnaire was used to collect epidemiological and behavioural data on the participants, which were analysed in a multivariate logistic regression model. The overall prevalence of CT was 4%, significantly higher in those under 25 years of age (5.8% versus 1.6% over 25). The independent risk factors for CT infection were: foreign origin (odds ratio [OR] 4.7; confidence interval [CI] 1.02-21.8), having had a sexual partner in the last three months (OR 4.59; CI 1.16-18.08) and tobacco use the last 12 months (OR 6.38; CI 1.16-34.93). In conclusion, this is the first study performed in Catalonia showing a high prevalence of CT in young women, consistent with trends in the rest of Europe. Systematic monitoring of CT infection in sentinel populations such as this will inform future targeted screening programmes in our setting.