RESUMO
Hospital-acquired pneumonia caused by Acinetobacter baumannii 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 A. baumannii pneumonia and further explore the effect of hcp on clinical, pathogenicity and drug resistance. 53 clinical A. baumannii 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 hcp. Recombinant Hcp expression plasmids (pET-28a(+)-hcp) 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 A. baumannii from the respiratory tract. His-tagged Hcp induced NF-κBp65 and IL-8 at gene level in THP-1 macrophages. Additional, high hcp 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 A. baumannii respiratory tract infection from colonization and participate in eliciting inflammatory responses in vitro. T6SS/hcp may play a role in the development of carbapenem-resistant A. baumannii (CRAB), multiple or extensive drug-resistant A. baumannii (MDRAB/XDRAB). Supplementary Information: The online version contains supplementary material available at 10.1007/s12088-023-01083-8.
RESUMO
AIMS: Low caspofungin exposure is frequently encountered in patients with invasive candidiasis caused by Candida albicans. This study aimed to investigate the effects of caspofungin on C. albicans at sub-inhibitory concentrations. METHODS AND RESULTS: First, a comparative transcriptomics analysis was performed on C. albicans receiving caspofungin at sub-minimum inhibitory concentrations (sub-MICs). The results showed that caspofungin significantly changed the mRNA expression profile in DAY185, with DE-mRNAs enriched in the functions of cell wall biosynthesis, metabolism, etc. Subsequently, cellular fitness, cell aggregation, energy metabolism activity and the proportion of persister cells of C. albicans were quantitatively and/or qualitatively assessed after sub-MIC caspofungin exposure. No significant changes in cell fitness and aggregation formation were observed during treatment of C. albicans with sub-MIC caspofungin. In C. albicans aggregation treated with sub-MIC caspofungin, we observed a decrease in respiratory metabolism and an increase in persister cells; this effect was more pronounced in als1ΔΔ than in DAY185. CONCLUSIONS: Pre-exposure to sub-MIC caspofungin suppresses C. albicans respiratory metabolism and promotes persister cell development. SIGNIFICANCE AND IMPACT OF THE STUDY: Caspofungin should be used with caution in patients with C. albicans infections, as anti-infection therapy may fail due to persister cells.