Objective Coagulase-negative staphylococci (CoNS) are one of the major opportunistic pathogens and the incidence of CoNS bacteraemia is increasing. However, most of the CoNS-positive blood cultures are contaminants rather than true CoNS bacteraemia. In order to minimize contamination, we defined true CoNS bacteraemia as the patient that has two or more identical CoNS-positive blood cultures drawn within 48 h in this study and the objective of this study was to analyse the species distribution and antibiotic resistance and to identify risk factors for 30-day mortality of the true CoNS-bacteraemia. Method By reviewing the electronic medical database, this study retrospectively analysed patients diagnosed as CoNS bacteraemia by blood cultures in a comprehensive tertiary care hospital in China from January 1, 2014, to December 31, 2017. Result A total of 1241 patients with 1562 episodes of CoNS-positive blood cultures were recorded in the database but only 157 patients were finally diagnosed as true CoNS bacteraemia after contaminants were excluded. All these 157 patients (12.7%, 157/1241) had bacteraemia-related clinical symptoms. Among the 157 patients, the most common species were Staphylococcus hominis (40.8%), Staphylococcus epidermidis (36.3%) and Staphylococcus capitis (11.5%). The antimicrobial susceptibility tests showed that all CoNS had a high rate of resistance to penicillin (94.9%), oxacillin (93.6%) and erythromycin (92.4%). Resistance to gentamicin (22.3%) and rifampicin (10.8%) was low, and none of the bacteria were resistant to vancomycin or linezolid. The 30-day mortality of patients with CoNS bacteraemia was up to 12.7% (20/157), and the multivariate logistics regression analysis showed that chronic renal failure (OR 5.9, 95% CI 1.6–21.5, p = 0.007) and chronic liver failure (OR 4.0, 95% CI 1.2–13.1, p = 0.024) were both the significant independent risk factors for the 30-day mortality of CoNS bacteraemia. Conclusion Staphylococcus hominis and Staphylococcus epidermidis were the most common species in CoNS bacteraemia. All CoNS had high multi-drug resistance, but gentamicin and rifampicin had a relatively lower resistance and could be considered as alternative antibiotics for anti-CoNS bacteraemia in addition to vancomycin and linezolid. Additionally, patients with chronic renal failure or chronic liver failure have a higher 30-day mortality after the onset of CoNS bacteraemia.

BackgroundGram-positive bacterial bloodstream infections (BSIs) are serious diseases associated with high morbidity and mortality. The following study examines the incidence, clinical characteristics and microbiological features, drug resistance situations and mortality associated with Gram-positive BSIs at a large Chinese tertiary-care hospital in Beijing, China.MethodsA retrospective cohort study of patients with Gram-positive BSIs was performed between January 1, 2011, and June 31, 2017, at the Chinese People’s Liberation Army General Hospital. The patients’ data were collected and included in the reviewing electronic medical records.ResultsA total of 6887 episodes of Gram-positive BSIs occurred among 4275 patients over 6 years, and there were 3438 significant BSI episodes 69% of these cases were healthcare-associated, while 31% were community-associated. The overall incidence of Gram-positive BSIs fluctuated from 7.26 to 4.63 episodes per 1000 admissions over 6 years. Malignancy was the most common comorbidity and indwelling central intravenous catheter was the most common predisposing factor for BSI. Staphylococci were the major pathogen (65.5%), followed by Enterococcus spp:(17.5%), Streptococcus spp.(7.1%) and other bacterial pathogens (9.9%). The resistance rates of Staphylococci and E.faecium to penicillins were more than 90%. the vancomycin-resistant isolates were E. faecium (4.1%) and staphylococcus epidermidis (0.13%); and only E.faecalis and E.faecium showed resistance to linezolid (3.8% and 3.1%). Between 2011 and 2017, the overall mortality of Gram-positive BSIs decreased from 6.27 to 4.75% (X2 = 0.912, p = 0.892). Neverthess, the mortality in the ICU decreased from 60.46 to 47.82%, while in the general ward it increased from 39.54 to 52.18%.ConclusionsThe morbidity and mortality of Gram-positive BSIs have showed downward trends. Vancomycin and linezolid are still consider the best treatment for patients with Gram-positive BSIs.

Staphylococcus aureus (S. aureus) is one of the most common clinical pathogenic bacteria with strong pathogenicity and usually leads to various suppurative infections with high fatality. Traditional bacterial culture for the detection of S. aureus is prone to diagnosis and antimicrobial treatment delays because of its long-time consumption and low sensitivity. In this study, we successfully developed a quantum dots immunofluorescence biosensor for S. aureus detection. The biosensor combined the advantages of biosensors with the high specificity of antigen-antibody immune interactions and the high sensitivity and stability of quantum dots fluorescence. The results demonstrated that the biosensor possessed high specificity and high sensitivity for S. aureus detection. The detection limit of S. aureus reached 1 × 104 CFU/ml or even 1 × 103 CFU/ml, and moreover, the fluorescence intensity had a significant positive linear correlation relationship with the logarithm of the S. aureus concentration in the range of 103–107 CFU/ml (correlation coefficient R2 = 0.9731, P = 0.011). A specificity experiment showed that this biosensor could effectively distinguish S. aureus (1 × 104 CFU/ml and above) from other common pathogenic (non-S. aureus) bacteria in nosocomial infections, such as Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii and Escherichia coli. Additionally, the whole detection procedure spent only 2 h. In addition, the biosensor in this study may not be affected by the interference of the biofilm or other secretions since the clinical biological specimens are need to be fully liquefied to digest and dissolve viscous secretions such as biofilms before the detection procedure of the biosensor in this study. In conclusion, the biosensor could meet the need for rapid and accurate S. aureus detection for clinical application.

Background Recent epidemiological studies on bloodstream infection (BSI) that include the proportion, species distribution and dynamic changes are scarce in China. This study was performed to understand these epidemiological data of BSI over the past 10 years in China. Methods Using a prospective nosocomial infection surveillance system, this study was retrospectively performed in one of the largest hospitals in China. The time trend was tested using the Cochran–Armitage trend test in R Programming Language. Results From 2010 to 2019, there were totally 9381 episodes of BSI cases out of 1,437,927 adult-hospitalized patients in the hospital, the total proportion of BSI cases was 6.50‰ (6.50 episodes per 1000 adult-hospitalized patients) and the proportion had significantly decreased (8.24–6.07‰, time trend P < 0.001). Among the 9381 episodes of BSI, 93.1% were bacteremia and others were fungemia (6.9%). As the most common species, the composition ratios of coagulase-negative staphylococcus (25.6–32.5%), Escherichia coli (9.8–13.6%) and Klebsiella pneumoniae (5.3–10.4%) had been dynamically increased (all time trends P < 0.05) and the proportion of Pseudomonas aeruginosa had decreased (4.0–2.4%, time trend P = 0.032). However, Staphylococcus aureus (3.3–3.1%) and Acinetobacter baumannii (4.4–4.2%) had not changed significantly (P > 0.05). These common species were consistent with China Antimicrobial Surveillance Network reported in 2018 (2018 CHINET report), but their composition ratios were different. In addition, among bacteremia, the proportion of multidrug-resistant bacteria gradually increased from 52.9 to 68.4% (time trend P < 0.001). Conclusion The proportion and species distribution of BSI were dynamically changing along certain trends. These trends deserved more attention from clinicians and researchers.

Significance and impact of the study: We isolated a heterogeneous vancomycin (VAN)-intermediate Staphylococcus aureus (hVISA) strain, and we demonstrated that the cell wall of the hVISA strain was significantly thicker than that of ordinary MRSA strains. The upregulated expression of glmS, vraR/S, sgtB, murZ and PBP4 genes related to cell wall synthesis might be the molecular mechanism underlying the cell wall thickening of the hVISA strain and might be related to its reduced sensitivity to VAN. These results could be used as a supplement to other hVISA-related studies in the world and might be beneficial to prevent and control the emergence of more hVISA.

The published data on the association between MCP-1 -2518A>G polymorphism and asthma susceptibility are inconclusive. Therefore, we performed a meta-analysis to estimate the impact of MCP-1 -2518A>G polymorphism on asthma susceptibility. PubMed, Web of Science, Wanfang, and China National Knowledge Infrastructure (CNKI) databases were used to identify eligible studies. The pooled odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were used to calculate the strength of association. Sensitivity analysis was performed to evaluate the influence of individual studies on the estimates of overall effect, and funnel plots and Egger's test were used to assess publication bias. Eight publications with 1562 asthma patients and 1574 controls were finally identified. Overall, we found no significant association between MCP-1 -2518A>G polymorphism and asthma susceptibility in any of the genetic model comparisons. After stratified analysis by ethnicity, the results showed that a significant association with asthma risk was found in Caucasians in all the genetic models. However, a protective association was found in Africans under the dominant model. The present meta-analysis suggested that the MCP-1 -2518 A>G polymorphism is a risk factor for asthma in the Caucasian population, nevertheless it has a protective effect in the African population.

Over the past few decades, understanding of the clinical features of pulmonary cryptococcosis (PC) has progressed, yet there is a lack of data on the manifestations of PC over time. To investigate the differences in clinical characteristics of PC across different time periods, we performed a retrospective review of 130 non-AIDS patients diagnosed with pathologically or microbiologically confirmed PC from 1990-2020. Among 130 PC patients, 24 (18.5%) exhibited immunosuppression, and 44 (33.8%) had underlying diseases. In radiology, 118 (90.8%) presented with subpleural lesions, and 68 (53.1%) presented with nodules with diameters ranging from 1-5 cm. Seventy-five patients (57.7%) underwent surgery alone. PC clinical features at different time periods showed that hospitalization days decreased (P=0.009), and patients with symptoms decreased over time. Patients exhibiting isolated lesions decreased (P=0.022), and patients exhibiting subpleural lesions increased (P=0.020). Patients with lesions presenting 3-10 mm nodules increased (P=0.028). In conclusion, more and more patients have been diagnosed of PC in the last 30 years. The timing of PC diagnosis has shifted to early in disease progression. Pulmonary lesions caused by cryptococcosis are easily misdiagnosed and may lead to unnecessary surgical treatment. Further research is needed to identify lung lesions caused by cryptococcosis.

Objective: Nocardiosis is a rare opportunistic infection caused by the Nocardia species. Nocardia bacteremia is a life-threatening presentation of disseminated nocardiosis that presents diagnostic and therapeutic challenges. We performed this retrospective analysis in a Chinese hospital from 2010 to 2019 to describe the characteristics of this rare bloodstream infection. Methods: We searched the database of the real-time nosocomial infection surveillance system and identified patients whose blood cultures showed Nocardia bacteria growth. The medical records of these patients were extracted and analyzed by two independent researchers. The data included age, gender, complicating disease, duration from blood drawing to reporting, clinical signs and symptoms, blood routine and C-reactive protein results, radiological examinations, sites of involvement, antibiotic treatments, and outcomes. Results: Seven patients with Nocardia bacteremia were found. There were four male and three female patients, whose ages ranged from 41 to 75 years. Six (85.7%) patients had predisposing conditions and were administrated corticosteroids for various reasons before the identification of Nocardia infection. The most common symptom was fever (100%). Five patients presented with lung or skin involvement; meanwhile, three patients presented with brain involvement. One patient presented with pelvic and peritoneum involvement, respectively. The most common findings of chest CT imaging were consolidation, followed by nodules and cavitations. Trimethoprim/sulfamethoxazole was prescribed to all patients after the diagnosis of Nocardia bacteremia. Six patients recovered, and one patient ultimately died. Conclusions: Nocardia bacteremia is a rare bloodstream infection that usually occurs in immunocompromised patients. Clinical manifestations of patients are nonspecific. It often causes multiple organ involvement, and early diagnosis and prompt aggressive interventions are important to improve the outcome of this disease.