Journal of Medical Microbiology - Current Issue

Introduction. Streptococcus suis is a zoonotic pathogen that causes invasive infections in humans who have been in close contact with infected pigs or contaminated pork-derived products. There is currently no consensus on the universal virulence factors or markers that can differentiate pathogenic from non-pathogenic or commensal S. suis isolates.

Gap statement. A diagnostic tool for serotyping and pathotyping of S. suis is required for active public health surveillance and the One-Health approach.

Aim. To improve the former multiplex PCR to serotyping all 29 recognized ‘true’ serotypes and distinguish pathogenic pathotypes using primers targeting the capsule and ROK pathogenic marker genes.

Methodology. Four sets of multiplex PCRs were modified and improved to detect all 29 recognized serotypes of S. suis and distinguish their pathogenic pathotypes using the ROK gene.

Results. This multiplex PCR allowed for the simultaneous amplification of S. suis-specific, serotype-specific and pathogenic pathotypes from the DNA of each serotype in each reaction. The accuracy, sensitivity, specificity, positive predictive value and negative predictive value of the pathogenic ROK marker genes were 84.7% (625/738), 96.4% (423/439), 67.6% (202/299), 81.4% (423/520) and 92.7% (202/218), respectively. There was a significant (P-value <0.001), high positive likelihood ratio [2.9 with 2.5–3.5 of 95% confidence interval (CI)] and a significant odds ratio (55.1 with 31.6–95.9 of 95 % CI), which indicated that the ROK gene could be used as the pathogenic pathotype marker. No cross-reactions were observed with other bacterial species.

Conclusion. This modified multiplex PCR was able to distinguish 29 well-known serotypes and predicted the pathogenic pathotypes of S. suis isolates from humans and pigs in a single assay. It is useful for One-Health surveillance of human and pig isolates of S. suis.

Introduction. Alcohol abuse can lead to significant cardiac injury, resulting in Alcoholic heart disease (AHD). The interplay between cardiac health and gut microbiota composition in the context of alcohol consumption is not well understood.

Hypothesis. Shen Song Yang Xin (SSYX) capsule and amiodarone are common drugs used to treat alcoholic heart disease, but little is known about their microbial regulatory mechanisms in alcoholic heart disease.

Aim. To investigate the effects of SSYX and amiodarone on cardiac injury and gut microbiota composition in a rat model of AHD induced by alcohol consumption.

Methodology. We evaluated body weight, cardiac function, changes in gut morphology, and gut microbiota composition to assess the effects of SSYX and amiodarone on AHD.

Results. Alcohol consumption significantly reduced body weight and aggravated cardiac fibrosis. However, SSYX attenuated fibrosis and improved cardiac function. SSYX also improved intestinal morphological changes caused by chronic alcoholism and activated the expression of ZO-1 and occludin, which are important in maintaining intestinal barrier function. The gut microbiota composition was altered in rats with AHD, with an increase in Actinobacteria abundance. Both SSYX and amiodarone affected the gut microbiota composition, and their effects were positively correlated. SSYX plays a protective role against heart injury caused by alcohol consumption. It improves cardiac function, intestinal morphological changes and gut microbiota composition.

Conclusion. SSYX and amiodarone may have potential therapeutic options for AHD. Actinobacteria/Firmicutes ratio and the abundance of Christensenellaceae R7 group, norank_flachnospiraceae and Roseburia may serve as potential biomarkers for detecting alcoholic heart disease.

Introduction. Infections by carbapenemase-producing Pseudomonas aeruginosa (CP-Pa) are concerning due to limited treatment options. The emergence of multidrug-resistant (MDR) high-risk clones is an essential driver in the global rise of CP-Pa.

Hypothesis/Gap Statement. Insights into the molecular epidemiology of CP-Pa are crucial to understanding its clinical and public health impact. Despite the low incidence of infections in Norway, global spread requires an understanding of regional dissemination patterns.

Aim. This study aimed to investigate the phenotypic and genotypic characteristics of CP-Pa isolates in Norway and molecular epidemiology by utilizing available metadata.

Methodology. The study collection comprised all verified CP-Pa isolated in Norway from 2006 to 2022 (n=67) obtained from clinical (75%; n=50) or screening samples (22%; n=15) or had no available information (3%; n=2). Phenotypic analyses included antimicrobial susceptibility testing against clinically relevant antipseudomonal antibiotics and comparative testing for carbapenemase production using three different methods (β-CARBA, IMI/IMD gradient test and Coris O.K.N.V.I RESIST-5). Whole-genome sequencing was performed to identify virulence factors, resistance determinants and genomic relatedness.

Results. The isolates were categorized as MDR (n=39) encoding Verona integron-encoded metallo-β-lactamase (VIM) (n=28), New Delhi metallo-β-lactamase (NDM) (n=6), imipenemase metallo-β-lactamase (IMP) (n=4) or Guiana extended spectrum metallo-β-lactamase (n=1) carbapenemases or extensively drug-resistant (XDR; n=28) encoding VIM (n=11), NDM (n=9) or IMP (n=8) carbapenemases. CP-Pa numbers ranged from 1 to 7 annually, peaking at 17 in 2022. Most isolates (n=64) were associated with international travel or hospitalization abroad. Phylogenetic analyses identified nine clusters of closely related genomes, with one suspected case of domestic patient-to-patient transmission. Among 21 detected sequence types, several were global high-risk clones, including ST235 (n=12), ST111 (n=9), ST773 (n=9), ST253 (n=3), ST357 (n=3), ST395 (n=3), ST823 (n=3), ST233 (n=2), ST654 (n=2), ST260 (n=1) and ST308 (n=1), covering 72% of the Norwegian isolates. ST1047 (IMP-1) and ST773 (NDM-1) were associated with Ukrainian war victims. Carbapenemase detection rates for phenotypic tests were 88% (β-CARBA), 91% (IMI/IMD) and 94% (Coris) in our collection.

Conclusion. The study highlights the low incidence yet high genomic diversity of CP-Pa in Norway and the dominance of high-risk clones linked to imports, contributing to the high proportion of XDR.

Introduction. Lamivudine plus dolutegravir (3TC/DTG) and bictegravir/emtricitabine/tenofovir alafenamide (B/F/TAF) regimens are commonly used as first-line treatments for people living with human immunodeficiency virus (HIV) (PLWH) worldwide.

Gap Statement. There are limited comparative data on the antiviral activity and safety between these regimens in ART-naive PLWH, particularly in China, where the 3TC/DTG regimen was integrated into first-line therapy in 2021 and gained broader adoption after its inclusion in the National Health Insurance in 2022.

Aims. This study aims to provide real-world evidence comparing the 3TC/DTG regimen to the B/F/TAF regimen in ART-naive PLWH in China.

Methodology. This retrospective study enrolled PLWH initiating ART with either 3TC/DTG or B/F/TAF in Shanghai from January 2020 to January 2023. Demographic characteristics and clinical information were collected and compared for each patient.

Results. A total of 380 eligible, ART-naive PLWH were included, with 190 patients in the 3TC/DTG group and 190 patients in the B/F/TAF group. Following the initiation of ART, most patients (94.1 and 89.3% for 3TC/DTG and B/F/TAF groups, respectively) achieved viral suppression (<50 copies of HIV RNA per millilitre) at week 24. The CD4 cell count significantly increased from a baseline of 301.3±185.8 cells per microlitre to 479.5±229.3 cells per microlitre at week 36 for the 3TC/DTG group and from 289.2±188.8 cells per microlitre at baseline to 487.8±234.2 cells per microlitre at week 36 for the B/F/TAF group. Both groups experienced an increase in blood lipid levels after initiating ART, with higher levels of high-density lipoprotein cholesterol (HDL-C) observed in the 3TC/DTG group compared with the B/F/TAF group. Renal and hepatic function indicators remained stable in both groups.

Conclusions. 3TC/DTG demonstrates similar antiviral efficacy to B/F/TAF and does not significantly impact liver and kidney functions. Patients receiving 3TC/DTG showed higher plasma HDL-C levels compared with those on B/F/TAF, which confer long-term clinical benefits in reducing cardiovascular risk.