Trieu Bao Nguyen

Staphylococcus aureus (S. aureus), especially Methicillin-resistant Staphylococcus aureus (MRSA), remains a major public health concern both in hospital and community settings. The MRSA carriage situation among schoolchildren in Vietnam is limited. A cross-sectional study was conducted in March 2023 to assess the prevalence, antimicrobial resistance patterns, and molecular characteristics of MRSA among schoolchildren in Nha Trang, Vietnam. Schoolchildren from grades 1 to 12 (ages 6–18 yrs) were enrolled. Background epidemiological data and nasal swabs were collected. Nasal samples were processed at the Pasteur Institute in Nha Trang, Vietnam, for S. aureus culture. Out of 1210 participants enrolled, S. aureus prevalence was 18.3% (222/1210), of which 41% (91/222) were MRSA. Primary school children showed the highest prevalence of MRSA colonization (48%), 32.8% in secondary, and 27.8% in high school. Among MRSA isolates, high levels of resistance were detected against trimethoprim-sulfamethoxazole (100%), erythromycin (68.2%) and clindamycin (45.1%). Multidrug resistance (MDR) occurred in 30% (27/90) of MRSA isolates. Staphylococcal cassette chromosome mec (SCCmec) subtype IVa was dominant (66.0%), followed by type IV (7.0%) and type V (6.0%). MLST data revealed genetic diversity whereby ST45 dominated, followed by ST546 and ST188. Continuous MRSA surveillance is essential to monitor emerging strains in the communities.

Background: Dengue is a global health concern, with half of the world’s population at risk and no antiviral treatment available. This Phase 0 study investigated dengue infections among household contacts (HHCs) of dengue index cases (ICs) and assessed the feasibility of conducting a Phase 2 trial for a novel antiviral. Methods: Participants were enrolled in Nha Trang, Vietnam, from April 2022 to February 2023. Dengue ICs were identified within 72 h of fever onset, and their healthy adult HHCs enrolled within 48 h. Blood samples and questionnaires were collected bi-weekly for four weeks, with a follow-up visit on day 40. DENV RT-qPCR, NS1, and anti-DENV IgM/IgG ELISAs were performed. Results: Overall, 130 dengue ICs and 301 HHCs were enrolled, with 91.7% (276/301) completing all follow-up visits. Baseline anti-DENV IgG showed prior dengue infections in 262/301 HHCs (87.0%). Fifty HHCs were excluded from the HHC infection analysis based on evidence of a DENV infection (viral load [VL], NS1, IgM, and IgG results) at enrollment. During follow-up, 2.0% of HHCs (5/251) had DENV infections based on virological parameters (DENV RNA and/or NS1 positivity), and anti-DENV IgG/IgM seroconversion was detected in 7.2% (18/251). Conclusions: This study demonstrated the operational feasibility of a dengue IC-HHC design for a Phase 2 trial.

We sampled nasal–pharyngeal throat swabs from 96,123 asymptomatic individuals at risk of SARS-CoV-2 infection, and generated 22,290 pools at collection, each containing samples from two to seven individuals. We detected SARS-CoV-2 in 24 pools, and confirmed the infection in 32 individuals after resampling and testing of 104 samples from positive pools. We completed the testing within 14 days. We would have required 64 days to complete the screening for the same number of individuals if we had based our testing strategy on individual testing. There was no difference in cycle threshold (Ct) values of pooled and individual samples. Thus, compared with individual sample testing, our approach did not compromise PCR sensitivity, but saved 77% of the resources. The present strategy might be applicable in settings, where there are shortages of reagents and the disease prevalence is low, but the demand for testing is high.