Objective To summarize the bioactive substances contained in bacterial extracellular vesicles (EVs) and their mechanisms in mediating bacterial-bacterial and bacterial-host interactions, as well as their mechanisms for use in implant infection-associated clinical guidance. Methods A wide range of publications on bacterial-derived EVs were extensively reviewed, analyzed, and summarized. Results Both gram-negative bacteria (G– bacteria) and gram-positive bacteria (G+ bacteria) can secrete EVs which contain a variety of bioactive substances, including proteins, lipids, nucleic acids, and virulence factors, and mediate bacterial-bacterial and bacterial-host interactions. EVs play an important role in the pathogenic mechanism of bacteria. Conclusion Bioactive substances contained within bacteria-derived EVs play an important role in the pathogenesis of bacterial infectious diseases. In-depth study and understanding of their pathogenic mechanisms can provide new insights which will improve early clinical diagnosis, prevention, and treatment of implant-associated infection. However, at present, research in this area is still in its infancy, and many more in-depth mechanisms need to be further studied.
Objective A comparative study of in-hospital mortality and risk factors of ventilator-associated pneumonia (VAP) caused by carbapenem-resistant gram-negative bacteria (CRGNB) and non-carbapenem-resistant gram-negative bacteria (nCRGNB) in China was conducted to investigate whether there is a higher in-hospital mortality of VAP caused by CRGNB and its unique associated risk factors. Methods Relevant literatures published at home and abroad in PubMed, EMBASE, Cochrane library, Web of Science, CNKI and Wanfang databases were retrieved from the date of establishment to June 1, 2021, and the quality of the included literatures was evaluated using Newcastle-Ottawa scale. Meta-analysis of literatures meeting the criteria was performed using RevMan 5.3 software. Results A total of 5 literatures were included, all of which were case-control studies with a total of 574 cases, including 302 cases in the CRGNB group and 272 cases in the nCRGNB group. The results showed that the in-patient mortality of VAP caused by CRGNB infection was significantly increased compared with that of VAP caused by nCRGNB infection (OR=2.51, 95%CI 1.71 - 3.67, P<0.00001). Risk factor analysis of CRGNB infection showed that statistically significant risk factors included mechanical ventilation duration ≥7 days (OR=2.66, 95%CI 1.23 - 5.75, P=0.01), secondary intubation (OR=4.48, 95%CI 2.61 - 7.69], P<0.00001), combined with antibiotics (OR=2.83, 95%CI 1.76 - 4.54, P<0.0001), using carbapenem antibiotics (OR=2.78, 95%CI 1.76 - 4.40, P<0.0001). In addition, two studies showed that tigecycline was sensitive to CRGNB in vitro. Conclusions Compared with nCRGNB-induced VAP, CRGNB infection significantly increases the in-hospital mortality of VAP patients in China, indicating that the in-hospital mortality of CRGNB infection is related to drug resistance, and had little relationship with region and drug resistance mechanism. Among them, mechanical ventilation duration ≥7 days, secondary intubation, combined use of antibiotics and carbapenem antibiotics are risk factors for CRGNB infection in VAP patients. Tigecycline is sensitive to most CRGNB strains in China and is an important choice for the treatment of CRGNB in China.