BackgroundInfective endocarditis (IE) especially in the elderly is a serious disease, with a worse prognosis.MethodsA retrospective cohort study was conducted. A total of 405 patients with definite IE were divided into three groups: 205 patients under 50 years old, 141 patients between 50 and 64 years old and 59 patients over 65 years old.ResultsFor older patients, clinical symptoms such as fever, anemia, and heart murmur were as common as the younger patients. IE in old patients had more frequent nosocomial origin (P = 0.007) and tended to be more frequent with bad oral hygiene (p = 0.008). The most frequent isolated pathogens in the old groups was streptococci and coagulase-negative staphylococci. The old patients had a lower operation rate (40.7% vs 58.9% vs 62.4%, P = 0.012) and higher in-hospital mortality (20.3% vs 10.6% vs 8.8%, P = 0.044) compared with the younger patients. Surgical treatment was a significant predictor of one-year mortality even after adjusting for the confounders (HR = 2.45, 95% CI 1.027–10.598, P = 0.009). The one-year survival rate was higher for older patients with surgical intervention than those without (95.8% vs 68.6%, P = 0.007).ConclusionsOlder patients with IE presented with more comorbidities, bad oral hygiene, more nosocomial origin and a more severe prognosis than younger patients. Streptococci was the most frequent micro-organisms in this group. Surgery were underused in old patients and those with surgical treatment had better prognosis.

To investigate the virulence of capsular polysaccharide export protein (Wza) in carbapenemresistant Acinetobacter baumannii and its effect on capsule formation. wza gene knockout and complementation strains were constructed, and changes in bacterial virulence were observed using in vitro adhesion, antiserum complement killing, anti-oxidation experiments, and infections in Galleria mellonella and mice. The effect of wza knockout on the genes wzb and wzc and wzi were assessed by RT-PCR. We successfully constructed wza knockout and complementation strains. Compared with wildtype (WT) strains, wza knockout strains displayed lower adhesion to A549 cells (p = 0.044), lower antiserum complement killing ability (p = 0.001), and lower mortality of G. mellonella (p = 0.010) and mice (p = 0.033). Expression levels of wzb, wzc and wzi were decreased in wza knockout strains. The antioxidant capacity of Wza knockout bacteria was only slightly decreased. Complementation of the wza gene returned the adhesion ability, antiserum complement killing ability, and mortality of G. mellonella and mice to WT levels. Expression of wzb, wzc and wzi was also returned to WT levels following wza complementation. The results clearly demonstrate that Wza is toxic. Wza affects the expression of other proteins of the Wzy capsule polysaccharide synthesis pathway, which affects the assembly, export, and extracellular fixation of capsular polysaccharide, resulting in synergistic effects that decrease bacterial virulence.

BackgroundCarbapenem-resistant Acinetobacter baumannii (CRAB) is a rapidly emerging, life-threatening nosocomial infection. This study aimed to explore the risk factors, clinical features, antimicrobial therapy, and outcomes of CRAB bloodstream infections (BSIs).MethodsThis is a retrospective, comparative analysis of data from patients with A. baumannii BSI, treated from 2012 to 2015 at a tertiary teaching hospital. Risk factors associated with CRAB BSI and factors associated with the 28-day mortality were evaluated using logistic analyses.ResultsData from 293 patients with confirmed A. baumannii BSI were included; 242 (82.6%) patients had CRAB BSI and 51 (17.4%) patients had non-CRAB BSI. Risk factors significantly associated with CRAB BSI were a previous intensive care unit (ICU) stay (P=0.029), cefoperazone–sulbactam use (P=0.030), and carbapenem use (P=0.004). Among 236 patients with A. baumannii BSI who were evaluable at 28 days after receiving antibacterial therapy, there were 86 deaths. Factors associated with the 28-day mortality were ICU stay after BSI (P=0.040), readmission within 90 days (P=0.029), Acute Physiology and Chronic Health Evaluation II (APACHE II) score at diagnosis >19 (P=0.012), tigecycline therapy (P=0.021), presence of septic shock (P=0.029), and multiple organ failure (P=0.016). Death rates in patients treated with tigecycline were 53.5% vs 24.1% in patients treated with other agents. Among 186 patients with CRAB BSI evaluable at 28 days, 84 patients died. The associated risk factors were an ICU stay after BSI (P=0.036), APACHE II score >19 at diagnosis (P = 0.002), presence of septic shock (P=0.030), and multiple organ failure (P=0.007).ConclusionThis study demonstrated that an ICU stay and cefoperazone–sulbactam or carbapenem use were seen to be the risk factors associated with the development of CRAB BSI. Critical illness and tigecycline therapy were significantly associated with higher mortality of patients with A. baumannii BSI.

Background We retrospectively analyzed the effect of tigecycline and cefoperazone/sulbactam therapies on the prognosis of patients with carbapenem-resistant Acinetobacter baumannii bloodstream infection (CRAB-BSI). Methods CRAB-BSI patients receiving tigecycline therapy or cefoperazone/sulbactam therapy between January 2012 and December 2017 was enrolled, and strict exclusion criteria were followed. The 28-day mortality of patients was analyzed. The impact of cefoperazone/sulbactam therapy on prognosis was evaluated using Cox multivariate regression analysis. The 28-day mortality of patients receiving cefoperazone/sulbactam monotherapy and cefoperazone/sulbactam-based combination therapy was also compared. Results Three hundred forty eight patients with CRAB-BSI were enrolled in the study. Two hundred ten patients were included after applying the exclusion criteria. Of these, 135 patients received tigecycline therapy and 75 patients received cefoperazone/sulbactam therapy. The 28-day mortality of patients in the latter group was, significantly lower than that of the tigecycline group [29.3% vs. 51.9%; P = 0.001]. Cox multivariate regression analysis revealed that cefoperazone/sulbactam therapy exerted a protective effect on the prognosis of patients [hazard ratio 0.566, 95% confidence interval (0.342–0.940); P = 0.028]. Kaplan-Meier survival curve analysis indicated that the 28-day mortality of patients receiving cefoperazone/sulbactam therapy was lower than that of patients receiving cefoperazone/sulbactam monotherapy, but the difference was not significant (22.2% vs. 40%; P = 0.074). However, the mortality of patients receiving cefoperazone/sulbactam with imipenem/cilastatin was significantly lower than that of patients receiving cefoperazone/sulbactam monotherapy ( P = 0.048). Conclusions Patients treated with cefoperazone/sulbactam therapy had a better clinical outcome. The mortality of patients receiving cefoperazone/sulbactam with imipenem/cilastatin seems to be the lowest. Electronic supplementary material The online version of this article (10.1186/s13756-019-0502-x) contains supplementary material, which is available to authorized users.