Evaluation of Prenatal Hepatitis C Virus Prevalence Using Universal Screening, and Linkage to Care in a Real-World Setting in Ontario

OBJECTIVES

International infectious disease/obstetrical societies have recently recommended universal hepatitis C virus (HCV) prenatal screening and these same recommendations are forthcoming in Canada. At present, there is no formal analysis of universal HCV screening or linkage to care of pregnant people in Ontario. The objectives of our study were to determine the seroprevalence of HCV using 2 different methods to evaluate universal screening, as well as identify opportunities that may improve linkage to care.

METHODS

To assess seroprevalence in a large urban area, we aimed to test 12 000 de-identified samples submitted for prenatal HIV testing in the catchment area of Toronto Public Health for HCV antibodies. Then, to assess the seroprevalence as well as the operational impact and follow-up in a real-world setting, we completed a Quality Improvement Project (QIP) for 1 year at a large tertiary care obstetrical centre in London, Ontario.

RESULTS

From 2019 to 2021, 11 999 de-identified samples were screened from Toronto with a seroprevalence of 0.40 (95% CI 0.29-0.53). In London, 5771 people were screened in 2021 with a seroprevalence of 0.55% (95% CI 0.38-0.78). Taken together, those aged 26-35 years had the highest positivity; in the QIP, 9% had no documented risk factor, and 59% of individuals were not linked to the next step in HCV care.

CONCLUSIONS

HCV prenatal seroprevalence in Ontario is comparable to hepatitis B virus, and ∼15-30-fold higher than HIV. Diagnosis in pregnancy is critical to facilitate referrals for treatment between pregnancies and could increase screening among children born to positive women.

Rapid detection of resistance to carbapenems and cephalosporins in Enterobacteriaceae using liquid chromatography tandem mass spectrometry

Carbapenemase producing Enterobacteriaceae (CPE) are becoming a global healthcare concern. Current laboratory methods for the detection of CPE include screening followed by confirmatory phenotypic and genotypic tests. These processes would generally take ≥72 hours, which could negatively impact patient care and Infection Control practices. To this end, we developed a protocol for rapid resistance testing (RRT) to detect hydrolysis in a panel of beta lactam antibiotics consisting of ampicillin, cefazolin, cefotaxime and imipenem, using liquid chromatography tandem mass spectrometry. Ninety—nine beta lactamase producing Enterobacteriaceae isolates were used to evaluate the RRT method, 54 isolates were CPE and 45 isolates were Class A or AmpC beta lactamase producing Enterobacteriaceae but not carbapenemase producers. We also tested 10 E.coli isolates that were susceptible to ampicillin, cefazolin, cefotaxime and imipenem. Receiver Operating Characteristic (ROC) Curves analysis showed that imipenem had a sensitivity and a specificity of 100% for crabapenemase detection at hydrolysis cut off values that are greater than 50% and less than or equal to 80%. The RRT protocol can be conducted in a time frame of less than 2 hours. This preliminary study shows that the rapid resistance testing protocol might have utility for the rapid detection of CPE. Additional work with a greater number and variety of beta- lactamase producing Enterobacteriaceae isolates is required to validate these preliminary findings.

Direct identification and antimicrobial susceptibility testing of microorganisms from positive blood cultures following isolation by lysis-centrifugation

We evaluated a direct from positive blood culture pelleting procedure that utilizes a lysis-centrifugation protocol for the identification of microorganisms by MALDI-TOF MS with subsequent antimicrobial susceptibility testing (AST) and rapid methicillin- and beta-lactam-resistance screening. The identification evaluation was performed on 125 cultures and resulted in the correct genus-level identification in 91.2% of cultures and a species-level concordance of 82.4% compared to routine subcultured growth. For the AST evaluation, susceptibility results from direct pelleting and subcultured growth for 187 cultures were compared; an average ±2-fold dilution agreement of 98.2% (1650/1681) and 98.6% (1375/1394) for Gram-negatives and -positives, respectively, was found. Major errors fell below 5% except for MRSA, which was falsely reported as oxacillin sensitive 17.2% (11/66) of the time. Lastly, the sensitivity and specificity of rapid MRSA screening were 94.7% (36/38) and 90.0% (9/10), respectively, while the ESBL screening results were 90.3% (65/72) and 100.0% (13/13) respectively.