Regular HIV testing and post-exposure prophylaxis among men who have sex with men in Lishui City / 预防医学

Objective@#To investigate the status of regular HIV testing and post exposure prophylaxis (PEP) behaviors among men who have sex with men (MSM) in Lishui City, Zhejiang Province, so as to provide the reference for developing targeted intervention strategies.@*Methods@#A total of 389 MSM were selected from Lishui City by convenient sampling method from April to August 2022, and demographic information, sexual behaviors, HIV testing and PEP behaviors were collected through questionnaire surveys. MSM were clustered using two step clustering analysis, and regular HIV testing and PEP behaviors among different groups of MSM were compared. Factors affecting regular HIV testing and PEP behaviors were evaluated using a multivariable logistic regression model.@*Results@#The MSM surveyed had a median age of 31.00 (interquartile range, 16.00) years. There were 146 MSM undergoing regular HIV testing, accounting for 37.53%, and 47 MSM receiving PEP, accounting for 12.08%. MSM were divided into two groups. There were 28.05% of MSM with regular HIV testing in group 1, which was lower than the 44.44% in group 2; and 22.56% receiving PEP, which was higher than the 4.44% in group 2 (both P<0.05). Multivariable logistic regression analysis identified age (OR=1.030, 95%CI: 1.011-1.050), sexual roles (both receptive and insertive, OR=2.999, 95%CI: 1.732-5.194) and homosexual behaviors in the past 6 months (use condoms every time, OR=4.567, 95%CI: 2.593-8.044) as factors affecting regular HIV testing among MSM; age (OR=0.970, 95%CI: 0.942-0.999), sexual orientation (OR=0.292, 95%CI: 0.139-0.612) and homosexual behaviors in the past 6 months (not use condoms, OR=0.135, 95%CI: 0.040-0.460; use condoms every time, OR=0.076, 95%CI: 0.018-0.326) as factors affecting PEP behaviors among MSM.@*Conclusion@#MSM with different characteristics of sexual behaviors have different preferences for HIV regular testing and PEP, with homosexual behaviors in the past 6 months, sexual roles and sexual orientation being the main influencing factors.

EsxA might as a virulence factor induce antibodies in patients with Staphylococcus aureus infection

Staphylococcus aureus (S. aureus) is an important human pathogen, which commonly causes the acquired infectious diseases in the hospital and community. Effective and simple antibiotic treatment against S. aureus-related disease becomes increasingly difficult. Developing a safe and effective vaccine against S. aureus has become one of the world's hot spots once again. The key issue of developing the vaccine of S. aureus is how to find an ideal key pathogenic gene of S. aureus. It was previously suggested that EsxA might be a very important factor in S. aureus abscess formation in mice, but clinical experimental evidence was lacking. We therefore expressed EsxA protein through prokaryotic expression system and purified EsxA protein by Ni-affinity chromatography. ELISA was used to detect the anti-EsxA antibodies in sera of 78 patients with S. aureus infection and results showed that the anti-EsxA antibodies were positive in the sera of 19 patients. We further analyzed the EsxA positive antibodies related strains by antimicrobial susceptibility assay and found that all of the corresponding strains were multi-drug resistant. Among those multi-drug resistant strains, 73.7% were resistant to MRSA. The results indicated EsxA is very important in the pathogenesis of S. aureus. We suggested that the EsxA is very valuable as vaccine candidate target antigens for prevention and control of S. aureus infection.

Expression of fljB: z66 on a linear plasmid of Salmonella enterica serovar typhi is dependent on FliA and FlhDC and regulated by OmpR

Salmonella enterica serovar Typhi z66-positive strains have two different flagellin genes, fliC:d/j and fljB:z66, located on the chromosome and on a linear plasmid, respectively. To investigate the mechanism underlying the expressional regulation of fljB:z66, gene deletion mutants of the regulators FliA, FlhDC, and OmpR were constructed in this study. The expression levels of fliC and fljB:z66 were analyzed by qRT-PCR in the wild-type strain and mutants at high and low osmolarity. The results show that the expression levels of both fljB:z66 and fliC were greatly reduced in fliA and flhDC mutants under both high and low osmotic conditions. In the ompR mutant, the expression levels of fljB:z66, fliC, fliA, and flhD were increased at low osmotic conditions. SDS-PAGE and western blotting analysis of the secreted proteins revealed that the FljB:z66 was almost absent in the fliA and flhDC mutants at both high and low osmolarity. In the wild-type strain, the fljB:z66 was more highly expressed under high-osmolarity conditions than under low-osmolarity conditions. However, this difference in expression disappeared in the ompR mutant. Translational expression assay of FljB:z66 showed that the FljB:z66 expression was decreased in ompR mutant at both low and high osmolarity. These results suggest that the expression of fljB:z66 in S. enterica serovar Typhi is dependent on FliA and FlihDC, and OmpR can regulate the expression and secretion of FljB:z66 in different osmolarity.