Background: In recent years, Candida parapsilosis is recognized as a species complex and is composed of Candida parapsilosis sensu stricto, Candida orthopsilosis and Candida metapsilosis. Candida parapsilosis complex prosthetic valve endocarditis (PVE) is rare and the survival rate is still low despite of optimal therapeutic strategies. In our report, it is novel to report cases as Candida parapsilosis complex PVE at species and identify Candida parapsilosis using MALDI-TOF MS. Case presentation A series of 4 cases of Candida parapsilosis complex PVE from our institution was reported. Three were infected by Candida parapsilosis sensu stricto and one was infected by Candida metapsilosis. The condition of two cases got better and the other died. Conclusions: More attention should be paid to Candida parapsilosis complex PVE and early diagnosis and prompt antibiotic therapy may play a role in the treatment for Candida parapsilosis complex PVE. It is recommended to identify Candida parapsilosis complex at species level and MALDI-TOF MS as an easy, fast and efficient identification method is worth promoting in clinical microbiology

Objectives: To report the notable increasing trends of C. tropicalis antifungal resistance in the past five years, and explore molecular epidemiology, and the relationship between clinical azoles consumption and increased resistance rate. Methods: Between August 2009 and July 2014, 507 non-duplicated C. tropicalis isolates causing invasive candidiasis were collected from ten hospitals in China. The in vitro antifungal susceptibility of nine common agents was determined by Sensititre YeastOneTM using current available species-specific clinical breakpoint (CBPs) or epidemiological cut-off values (ECVs). A high discriminatory three-loci (ctm1, ctm3 and ctm24) microsatellite scheme was used for typing of all isolates collected. Clinical consumption of fluconazole and voriconazole was obtained and the Defined Daily Dose measurement units were assigned to the data. Results: Overall, 23.1% and 20.7% of isolates were non-susceptible to fluconazole and voriconazole, respectively. And over five years, the non-susceptible rate of C. tropicalis isolates to fluconazole and voriconazole continuously increased from 11.2% to 42.7% for fluconazole (P<0.001), and from 10.4% to 39.1% for voriconazole (P<0.001). Four genotype clusters were observed to be associated with fluconazole non-susceptible phenotype. However, the increase in azole non-susceptible rate didn’t correlate with clinical azole consumption. Conclusions: The rapid emergence of azole resistant C. tropicalis strains in China is worrying, and continuous surveillance is warranted and if the trend persists, empirical therapeutic strategies for C. tropicalis invasive infections should be modified.

Purpose: The discovery of the plasmid-mediated colistin resistance genes, mcr, revealed a mechanism of transmission of colistin resistance, which is a major, global public health concern especially among individuals infected with carbapenem-resistant Gram-negative bacteria. To monitor the spread and epidemiology of mcr genes, a convenient and reliable method to detect mcr genes in clinical isolates is needed, especially in the primary care institutions. This study aimed to establish a restriction endonuclease-based multiplex loop-mediated isothermal amplification (multi-LAMP) assay to detect mcr genes (mcr-1 to mcr-5) harbored by colistin-resistant bacteria. Methods: A triple-LAMP assay for mcr-1, mcr-3, and mcr-4 and a double-LAMP assay for mcr-2 and mcr-5 were established. The sensitivity and specificity of the LAMP reactions were determined via electrophoresis and visual detection. Results: The sensitivity of the LAMP assay was 10-fold greater than that of PCR, with high specificity among the screened primers. Specific mcr genes were distinguished in accordance with band numbers and the fragment length of the digested LAMP amplification products. Furthermore, the LAMP assay was confirmed as a rapid and reliable diagnostic technique upon application for clinical samples, and the results were consistent with those of conventional PCR assay. Conclusion: The multi-LAMP assay is a potentially promising method to detect mcr genes and will, if implemented, help prevent infections by drug-resistant bacteria in primary-care hospitals due to rapid and reliable surveillance. To our knowledge, this is the first study to report the application of LAMP to detect mcr-2 to mcr-5 genes and the first time that multi-LAMP has been applied to detect mcr genes.

Background: Bloodstream infection (BSI) caused by carbapenem resistant Klebsiella pneumoniae (CRKP), especially in elderly patients, results in higher morbidity and mortality. The purpose of this study was to assess risk factors associated with CRKP BSI and short-term mortality among elderly patients in China. Methods: In this retrospective cohort study, we enrolled 252 inpatients aged ≥ 65 years with BSI caused by KP from January 2011 to December 2020 in China. Data regarding demographic, microbiological characteristics, and clinical outcome were collected. Result: Among the 252 BSI patients, there were 29 patients (11.5%) caused by CRKP and 223 patients (88.5%) by carbapenem-susceptible KP (CSKP). The overall 28-day mortality rate of elderly patients with a KP BSI episode was 10.7% (27/252), of which CRKP BSI patients (14 / 29, 48.3%) were significantly higher than CSKP patients (13 / 223, 5.83%) (P < 0.001). Hypertension (OR: 13.789, [95% CI: 3.883–48.969], P < 0.001), exposure to carbapenems (OR: 8.073, [95% CI: 2.066–31.537], P = 0.003), and ICU stay (OR: 11.180, [95% CI: 2.663–46.933], P = 0.001) were found to be associated with the development of CRKP BSI in elderly patients. A multivariate analysis showed that isolation of CRKP (OR 2.881, 95% CI 1.228–6.756, P = 0.015) and KP isolated in ICU (OR 11.731, 95% CI 4.226–32.563, P < 0.001) were independent risk factors for 28-day mortality of KP BSI. Conclusion: In elderly patients, hypertension, exposure to carbapenems and ICU stay were associated with the development of CRKP BSI. Active screening of CRKP for the high-risk populations, especially elderly patients, is significant for early detection and successful management of CRKP infection.

To evaluate in vitro susceptibilities of aerobic and facultative Gram-negative bacterial (GNB) isolates from intra-abdominal infections (IAIs) to 12 selected antimicrobials in Chinese hospitals from 2012 to 2014. Hospital acquired (HA) and community acquired (CA) IAIs were collected from 21 centers in 16 Chinese cities. Extended spectrum beta-lactamase (ESBL) status and antimicrobial susceptibilities were determined at a central laboratory using CLSI broth microdilution and interpretive standards. From all isolated strains the Enterobacteriaceae (81.1%) Escherichia coli accounted for 45.4% and Klebsiella pneumoniae for 20.1%, followed by Enterobacter cloacae (5.2%), Proteus mirabilis (2.1%), Citrobacter freundii (1.8%), Enterobacter aerogenes (1.8%), Klebsiella oxytoca (1.4%), Morganella morganii (1.2%), Serratia marcescens (0.7%), Citrobacter koseri (0.3%), Proteus vulgaris (0.3%) and others (1.0%). Non- Enterobacteriaceae (18.9%) included Pseudomonas aeruginosa (9.8%), Acinetobacter baumannii (6.7%), Stenotrophomonas maltophilia (0.9%), Aeromonas hydrophila (0.4%) and others (1.1%). ESBL-screen positive Escherichia coli isolates (ESBL+) showed a decreasing trend from 67.5% in 2012 to 58.9% in 2014 of all Escherichia coli isolates and the percentage of ESBL+ Klebsiella pneumoniae isolates also decreased from 2012 through 2014 (40.4% to 26.6%), which was due to reduced percentages of ESBL+ isolates in HA IAIs for both bacteria. The overall susceptibilities of all 5160 IAI isolates were 87.53% to amikacin (AMK), 78.12% to piperacillin-tazobactam (TZP) 81.41% to imipenem (IMP) and 73.12% to ertapenem (ETP). The susceptibility of ESBL-screen positive Escherichia coli strains was 96.77%–98.8% to IPM, 91.26%–93.16% to ETP, 89.48%–92.75% to AMK and 84.86%–89.34% to TZP, while ESBL-screen positive Klebsiella pneumoniae strains were 70.56%–80.15% susceptible to ETP, 80.0%–87.5% to IPM, 83.82%–87.06% to AMK and 63.53%–68.38% to TZP within the three year study. Susceptibilities to all cephalosporins and fluoroquinolones were less than 50% beside 66.5% and 56.07% to cefoxitin (FOX) for ESBL+ Escherichia coli and Klebsiella pneumoniae strains respectively. The total ESBL+ rates decreased in Escherichia coli and Klebsiella pneumoniae IAI isolates due to fewer prevalence in HA infections. IPM, ETP and AMK were the most effective antimicrobials against ESBL+ Escherichia coli and Klebsiella pneumoniae IAI isolates in 2012–2014 and a change of fluoroquinolone regimens for Chinese IAIs is recommended.