Value of T6SS Core Gene in Respiratory Tract Infection.

Unlabelled: Hospital-acquired pneumonia caused by is a major healthcare burden. Type VI Secretion System (T6SS) contributes to both virulence and drug resistance in this bacteria. This study aims to investigate the diagnostic value of hemolysin co-regulated protein (Hcp) gene in pneumonia and further explore the effect of on clinical, pathogenicity and drug resistance. 53 clinical strains from patients' respiratory tract at a teaching hospital were included in this study. Real-time quantitative polymerase chain reaction (qRT-PCR) was carried out to examine the expression of . Recombinant Hcp expression plasmids (pET-28a(+)-) were constructed and his-tagged Hcp were purified to stimulate Tohoku Hospital Pediatrics-1 (THP-1) macrophages. Nuclear Factor Kappa B p65 (NF-κBp65) and Interleukin 8 (IL-8) were detected by qRT-PCR. Antimicrobial susceptibility testing (AST) were examined by an automated instrument system. Hcp gene had 92.6% sensitivity and 75% specificity for distinguishing invasive or colonizing from the respiratory tract. His-tagged Hcp induced NF-κBp65 and IL-8 at gene level in THP-1 macrophages. Additional, high expression isolates showed higher rate of antimicrobial agent exposure (< 30 days) of carbapenems, antibiotic combination therapy and multiple or extensive drug-resistant (MDR/XDR) and exhibited higher resistance rate to clinical commonly-used antimicrobial agents. Hcp gene could serve as a novel diagnostic biomarker to distinguish  respiratory tract infection from colonization and participate in eliciting inflammatory responses in vitro. T6SS/ may play a role in the development of carbapenem-resistant   (CRAB), multiple or extensive drug-resistant  (MDRAB/XDRAB).

Supplementary Information: The online version contains supplementary material available at 10.1007/s12088-023-01083-8.