Carbapenem-resistant Enterobacter cloacae complex in a tertiary Hospital in Northeast China, 2010-2019.

BACKGROUND: Carbapenem-resistant Enterobacter cloacae complex (CREC) is a new emerging threat to global public health. The objective of the study was to investigate the clinical characteristics and molecular epidemiology of CREC infections in the medical center of northeast China. METHODS: Twenty-nine patients were infected/colonized with CREC during a ten-year period (2010-2019) by WHONET analysis. Antibiotic susceptibilities were tested with VITEK 2 and micro broth dilution method (for polymyxin B and tigecycline). Carbapenemase encoding genes, ß-lactamase genes, and seven housekeeping genes for MLST were amplified and sequenced for 18 cryopreserved CREC isolates. Maximum likelihood phylogenetic tree was built with the concentrated sequences to show the relatedness between the 18 isolates. RESULTS: There was a rapid increase in CREC detection rate during the ten-year period, reaching 8.11% in 2018 and 6.48% in 2019. The resistance rate of CREC isolates to imipenem and meropenem were 100.0 and 77.8%, however, they showed high sensitivity to tigecycline, polymyxin B and amikacin. The 30-day crude mortality of CREC infection was 17.4%, indicating that it may be a low-virulence bacterium. Furthermore, molecular epidemiology revealed that ST93 was the predominant sequence type followed by ST171 and ST145, with NDM-1 and NDM-5 as the main carbapenemase-encoding genes. Moreover, E. hormaechei subsp. steigerwaltii and E. hormaechei subsp. oharae were the main species, which showed different resistance patterns. CONCLUSION: Rising detection rate of CREC was observed in a tertiary hospital, which showed heterogeneity in drug resistance patterns, resistance genes, and MLST types. Effective infection prevention and control measures should be taken to reduce the spread of CREC.

Pharmacokinetic and pharmacodynamic profiling of four antimicrobials against Acinetobacter baumannii infection.

BACKGROUND: The aim of this study was to evaluate common antimicrobial regimens used in eradicating Acinetobacter baumannii in Shenyang, China. METHODS: Monte Carlo simulation was conducted to estimate the probability target attainment (PTA) and cumulative fraction of response (CFR) for imipenem, cefoperazone/sulbactam (2:1), tigecycline and colistin methanesulfonate. RESULTS: For the results of PTAs, imipenem following administration of 0.5 g q6 h, 1 g q8 h, and 1 g q6 h for both 0.5 h and 2 h infusion achieved＞90% PTAs when MIC was 8 µg/ml; cefoperazone/ sulbactam (2:1) following administration of 4.5 g q6 h and 6 g q6 h achieved＞90% PTAs when MIC was 64µg/ml; tigecycline following administration of 50 mg q12 h and 100 mg q12 h achieved＞90% PTAs when MIC was 1 µg/ml; colistin methanesulfonate with high dosages (3MU q8 h) could provide high PTA (95.13%) in patients with CLCr＜60 ml/min when MIC was 2 µg/ml. As for CFR values of four antibiotics, imipenem achieved the lowest CFR values. For cefoperazone/sulbactam (2:1) and tigecycline, with simulated regimens improvement, the CFR values were both increased, and there were obviously increasing CFR values against Acinetobacter baumannii. For colistin methanesulfonate, the most aggressive dosage of 3MU q8 h could provide satisfactory CFR values (≥86.94%) against Acinetobacter baumannii in patients at various CLCr. CONCLUSION: This study suggested that measurement of MICs, individualized therapy and therapeutic drug-level monitoring should be considered together to achieve the optimal drug exposure. That will provide the best chance of achieving the highest probability of a successful clinical or microbiological response, and avoiding the induced resistance.

Is the superbug fungus really so scary? A systematic review and meta-analysis of global epidemiology and mortality of Candida auris.

BACKGROUND: Candida auris is a new pathogen called "superbug fungus" which caused panic worldwide. There are no large-scale epidemiology studies by now, therefore a systematic review and meta-analysis was undertaken to determine the epidemic situation, drug resistance patterns and mortality of C. auris. METHODS: We systematically searched studies on the clinical report of Candida auris in Pubmed, Embase and Cochrane databases until October 6, 2019. A standardized form was used for data collection, and then statics was performed with STATA11.0. RESULTS: It showed that more than 4733 cases of C. auris were reported in over 33 countries, with more cases in South Africa, United States of America, India, Spain, United Kingdom, South Korea, Colombia and Pakistan. C. auirs exhibited a decrease in case count after 2016. Clade I and III were the most prevalent clades with more cases reported and wider geographical distribution. Blood stream infection was observed in 32% of the cases, which varied depending on the clades. Resistance to fluconazole, amphotericin B, caspofungin, micafungin and anidulafungin in C. auris were 91, 12, 12.1, 0.8 and 1.1%. The overall mortality of C. auris infection was 39%. Furthermore, subgroup analyses showed that mortality was higher in bloodstream infections (45%), and lower in Europe (20%). CONCLUSIONS: Over 4000 cases of C. auris were reported in at least 33 countries, which showed high resistance to fluconazole, moderate resistance to amphotericin B and caspofungin, high sensitivity to micafungin and anidulafungin. The crude mortality for BSI of C. auris was 45% which was similar to some drug-resistant bacteria previously reported. In conclusion, C. auris displayed similar characteristics to some drug resistance organisms. This study depicts several issues of C. auris that are most concerned, and is of great significance for the clinical management.

Clinical Characteristics and Outcomes of Candidemia Caused by Meyerozyma guilliermondii Complex in Cancer Patients Undergoing Surgery.

Although Meyerozyma guilliermondii complex is an uncommon cause of invasive candidiasis worldwide, reported cases, mainly regarding bloodstream infections, increased over years, and patients with cancer who have undergone recent surgery are most commonly affected. However, the clinical characteristics and outcomes of candidemia caused by M. guilliermondii complex remain poorly understood. A retrospective case-control study was conducted to evaluate the clinical characteristics and mortality of candidemia caused by M. guilliermondii complex in cancer patients undergoing surgery. Demographic and clinical data were collected from the hospital medical records system with a standardized data collection form and were analyzed with SPSS 20.0. Sixty-six cancer patients who have undergone recent surgery and were diagnosed with candidemia caused by M. guilliermondii complex were included in the study. Regarding the clinical manifestations, most patients' body temperatures ranged from 38 to 40 °C, with a median fever duration of 4 (IQR: 3-6) days. Multivariate analysis indicated that the presence of central venous catheter (OR: 6.68; 95% CI 2.80-15.94) and gastric tube (OR: 3.55; 95% CI 1.22-10.34) were independent risk factors for M. guilliermondii complex fungemia. The 30-day crude mortality of candidemia caused by M. guilliermondii complex was 12.1%, twice that of the control group. Moreover, increased WBC count, age ≥ 60 years, septic shock, and ICU admission were identified as predictors of mortality through univariate analysis. These findings will provide a foundation for the clinical management of candidemia caused by M. guilliermondii complex in post-surgical cancer patients.

Antimicrobial susceptibilities of aerobic and facultative gram-negative bacilli isolated from Chinese patients with urinary tract infections between 2010 and 2014.

BACKGROUND: The objective of this study was to investigate the distribution and susceptibility of aerobic and facultative Gram-negative bacilli isolated from Chinese patients with UTIs collected within 48 h (community acquired, CA) or after 48 h (hospital acquired, HA) of hospital admission. METHODS: From 2010 to 2014, the minimum inhibitory concentrations (MICs) of 12 antibiotics for 4,332 aerobic and facultative Gram-negative bacilli, sampled in 21 hospitals in 16 cities, were determined by the broth microdilution method. RESULTS: Enterobacteriaceae composed 88.5% of the total isolates, with Escherichia coli (E. coli) (63.2%) the most commonly isolated species, followed by Klebsiella pneumoniae (K. pneumoniae) (12.2%). Non-Enterobacteriaceae accounted for only 11.5% of all isolates and included mainly Pseudomonas aeruginosa (P. aeruginosa) (6.9%) and Acinetobacter baumannii (A. baumannii) (3.3%). Among the antimicrobial agents tested, the susceptibility rates of E.coli to the two carbapenems, ertapenem and imipenem as well as amikacin and piperacillin-tazobactam ranged from 92.5 to 98.7%. Against K. pneumonia, the most potent antibiotics were imipenem (92.6% susceptibility), amikacin (89.2% susceptibility) and ertapenem (87.9% susceptibility). Although non-Enterobacteriaceae did not show high susceptibilities to the 12 common antibiotics, amikacin exhibited the highest in vitro activity against P. aeruginosa over the 5-year study period, followed by piperacillin-tazobactam, imipenem, ceftazidime, cefepime, ciprofloxacin, and levofloxacin. The Extended Spectrum Beta-Lactamase (ESBL) rates decreased slowly during the 5 years in E. coli from 68.6% in 2010 to 59.1% in 2014, in K. pneumoniae from 59.7 to 49.2%, and in Proteus mirabilis (P. mirabilis) from 40.0 to 26.1%. However, the ESBL rates were different in 5 regions of China (Northeast, North, East, South and Middle-China). CONCLUSION: E. coli and K. pneumonia were the major pathogens causing UTIs and carbapenems and amikacin retained the highest susceptibility rates over the 5-year study period, indicating that they are good drug choices for empirical therapies, particularly of CA UTIs in China.

Serotype distribution and antibiotic resistance of Streptococcus pneumoniae isolates from 17 Chinese cities from 2011 to 2016.

BACKGROUND: Streptococcus pneumoniae, the leading pathogen of bacterial infections in infants and the elderly, is responsible for pneumococcal diseases with severe morbidity and mortality. Emergence of drug-resistant strains presented new challenges for treatment and prevention. Vaccination has proven to be an effective means of preventing pneumococcal infection worldwide. Detailed epidemiological information of antibiotic susceptibilities and serotype distribution will be of great help to the management of pneumococcal infections. METHODS: A total of 881 S. pneumoniae isolates were collected from patients at 23 teaching hospitals in 17 different cities from 2011 to 2016. The main specimen types included sputum, blood, broncho-alveolar lavage fluid, pharyngeal swabs, and cerebrospinal fluid. Minimum inhibitory concentrations (MICs) were determined using the agar dilution method. Capsular serotypes were identified using latex agglutination and quellung reaction test. Molecular epidemiology was investigated using multilocus sequence typing. RESULTS: S. pneumoniae isolates were highly resistant to macrolides, tetracycline, and trimethoprim/sulfamethoxazole. The rate of resistance to penicillin was 51.6% (oral breakpoint). However, levofloxacin and moxifloxacin maintained excellent antimicrobial activity and all of the isolated strains were susceptible to vancomycin. Twenty-two serotypes were identified among the 881 isolates. Prevalent serotypes were 19F (25.7%), 19A (14.0%), 15 (6.8%), 6B (3.6%), 6A (3.0%), and 17 (2.8%). The overall vaccine coverage rates for 7- and 13-valent pneumococcal conjugate vaccines were 37.5% and 58.3%, respectively. Vaccine coverage rates in young children and economically underdeveloped regions were higher than those in older adults and developed regions. Vaccine-covered serotypes demonstrated higher resistance compared with uncovered serotypes. Molecular epidemiological typing demonstrated that S. pneumoniae showed significant clonal dissemination and that ST271 (120, 28.3%), ST320 (73, 17.2%) and ST81 (27, 6.6%) were the major STs. CONCLUSIONS: High resistance to clinical routine antibiotics was observed for all 881 S. pneumoniae strains. Drug resistance varied among different serotypes and age groups. Prevalent serotypes among the isolates were 19F, 19A, 15, 6B, 6A, and 17. Community-acquired strains should also be included in future studies to gain a better understanding of the prevalence and resistance of S. pneumoniae in China.

Update of incidence and antimicrobial susceptibility trends of Escherichia coli and Klebsiella pneumoniae isolates from Chinese intra-abdominal infection patients.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Antimicrobial Susceptibilities of Aerobic and Facultative Gram-Negative Bacilli from Intra-abdominal Infections in Patients from Seven Regions in China in 2012 and 2013.

To evaluate the antimicrobial susceptibility of Gram-negative bacilli that caused hospital-acquired and community-acquired intra-abdominal infections (IAIs) in China between 2012 and 2013, we determined the susceptibilities to 12 antimicrobials and the extended-spectrum ß-lactamase (ESBL) statuses of 3,540 IAI isolates from seven geographic areas in China in a central laboratory using CLSI broth microdilution and interpretive standards. Most infections were caused by Escherichia coli (46.3%) and Klebsiella pneumoniae (19.7%). Rates of ESBL-producing E. coli (P = 0.031), K. pneumoniae (P = 0.017), and Proteus mirabilis (P = 0.004) were higher in hospital-acquired IAIs than in community-acquired IAIs. Susceptibilities of enterobacteriaceae to ertapenem, amikacin, piperacillin-tazobactam, and imipenem were 71.3% to 100%, 81.3% to 100%, 64.7% to 100%, and 83.1% to 100%, respectively, but imipenem was ineffective against P. mirabilis (<20%). Although most ESBL-positive hospital-acquired isolates were resistant to third- and fourth-generation cephalosporins, the majority were susceptible to cefoxitin (47.9% to 83.9%). Susceptibilities of ESBL-positive isolates to ampicillin-sulbactam (<10%) were low, whereas susceptibilities to ciprofloxacin (0% to 54.6%) and levofloxacin (0% to 63.6%) varied substantially. The prevalences of cephalosporin-susceptible E. coli and K. pneumoniae were higher in the northeastern and southern regions than in the central and eastern regions, reflecting the ESBL-positive rates in these areas, and were lowest in the Jiangsu-Zhejiang (Jiang-Zhe) area where the rates of carbapenem resistance were also highest. Ertapenem, amikacin, piperacillin-tazobactam, and imipenem are the most efficacious antibiotics for treating IAIs in China, especially those caused by E. coli or K. pneumoniae. Resistance to cephalosporins and carbapenems is more common in the Jiang-Zhe area than in other regions in China.

Antifungal susceptibilities of Candida glabrata species complex, Candida krusei, Candida parapsilosis species complex and Candida tropicalis causing invasive candidiasis in China: 3 year national surveillance.

OBJECTIVES: To define the antifungal susceptibility patterns of the most common non-albicans Candida spp. in China. METHODS: We evaluated the susceptibilities to nine antifungal drugs of Candida parapsilosis species complex, Candida tropicalis, Candida glabrata species complex and Candida krusei isolates from patients with invasive candidiasis at 11 hospitals over 3 years. Isolates were identified by MALDI-TOF MS supplemented by DNA sequencing. MICs were determined by Sensititre YeastOne(TM) using current clinical breakpoints/epidemiological cut-off values to assign susceptibility (or WT), and by CLSI M44-A2 disc diffusion for fluconazole and voriconazole. RESULTS: Of 1072 isolates, 392 (36.6%) were C. parapsilosis species complex. C. tropicalis, C. glabrata species complex and C. krusei comprised 35.4%, 24.3% and 3.7% of the isolates, respectively. Over 99.3% of the isolates were of WT phenotype to amphotericin B and 5-flucytosine. Susceptibility/WT rates to azoles among C. parapsilosis species complex were ≥97.5%. However, 11.6% and 9.5% of C. tropicalis isolates were non-susceptible to fluconazole and voriconazole, respectively (7.1% were resistant to both). Approximately 14.3% of C. glabrata sensu stricto isolates (n = 258) were fluconazole resistant, and 11.6% of C. glabrata sensu stricto isolates were cross-resistant to fluconazole and voriconazole. All C. krusei isolates were susceptible/WT to voriconazole, posaconazole and itraconazole. Overall, 97.7%-100% of isolates were susceptible to caspofungin, micafungin and anidulafungin, but 2.3% of C. glabrata were non-susceptible to anidulafungin. There was no azole/echinocandin co-resistance. Disc diffusion and Sensititre YeastOne(TM) methods showed >95% categorical agreement for fluconazole and voriconazole. CONCLUSIONS: In summary, reduced azole susceptibility was seen among C. tropicalis. Resistance to echinocandins was uncommon.

[Antimicrobial resistance monitoring of gram-negative bacilli isolated from 15 teaching hospitals in 2014 in China].

OBJECTIVE: To investigate the current situation of antimicrobial resistance of nosocomial gram-negative bacilli in 2014 in China. METHODS: About 1 430 consecutive and non-repetitive strains of gram-negative bacilli were isolated from 15 teaching hospitals from March to August in 2014. All of these isolates were sent to the central laboratory for reidentification and susceptibility testing. The minimal inhibitory concentration (MIC) of meropenem and other antibacterial agents were determined by agar dilution method. The data were analyzed by using WHONET-5.6 software. RESULTS: The activity of antimicrobial agents against Enterobacteriaceae was listed as followings in descending order of susceptibility: meropenem (94.7%, 913/964), amikacin (94.4%, 910/964), imipenem (88.5%, 853/964), ertapenem (87.8%, 847/964), piperacillin-tazobactam (87.2%, 841/964), cefoperazone-sulbactam (86.7%, 836/964), polymyxin B (77%, 742/964), cefepime (74.5%, 718/964), cefiazidime (71.8%, 692/964), levofloxacin (71.1%, 685/964), ciprofloxacin (67.7%, 653/964), minocyline (64.2%, 619/964), ceftriaxone (56.8%, 548/964), cefotaxime (55.8%, 538/964), cefoxitin (45.5%, 439/964). The prevalence of extended-spectrum beta-lactamases (ESBLs) was 57.6% (114/198) in E. coli and 24.6% (49/199) in Klebsiella pneumonia. The sensitivity of E. coli to carbapenems, amikacin, piperacillin-tazobactam, polymyxin B and cefoperazone-sulbactam was all over 80%. However, over 60% E. coli strains were resistant to ciprofloxacin, levofloxacin, ceftriaxone and cefotaxime. Polymyxin B was the most susceptible antibiotic to Klebsiella pneumoniae (99.5% sensitive), followed by amikacin (89.9%), meropenem (86.4%), imipenem (86.4%) and piperacillin-tazobactam (81.9%), while ceftriaxone (60.8%) and cefotaxime (59.8%) were less sensitive. The activity of antimicrobial agents against E. cloacae, E. aerogenes and Citrobacter freundii was listed as followings in descending order of susceptibility: meropenem (96.1%-97.4%), imipenem (95.1%-97.1%), polymyxin B (92.6%-99.0%), cefoperazone/sulbactam (87.3%-92.6%), ertapenem (85.6%-93.3%), piperacillin-tazobactam (65.0%-89.8%). The susceptibility rates of meropenem, cefoperazone-sulbactam, piperacillin-tazobactam, cefepime to Proteus mirabilis, Proteus vulgaris and Morganella morganii were all more than 90.0%. The most active agents against Pseudomonas aeruginosa were polymyxin B (99.5%), followed by amikacin (92.0%) and ciprofloxacin (82.1%). A. baumanni was most susceptible to polymyxin B (99.0%), while resistant to imipenem, meropenem and cefoperazone-sulbactam (29.2%, 28.2% and 29.7% respectively), mediate to minocycline (67.0%). Based on the new breakpoints for cefepime to Enterobacteriaceae, the drug susceptible rates decreased 25.8% to E. coli and 14.7% to E. cloacae. CONCLUSIONS: Carbapenems remain high susceptibility against Enterobacteriaceae, however carbapenem-resistant Enterobacteriaceae (CREs) have emerged. The sensitivity of Enterobacteriaceae against cefepime has been decreased according to the new breakpoint. Multi-drug resistant A. baumanni should be monitored persistently.

[Analysis of pathogen spectrum and resistance of clinical common organisms causing bloodstream infections, hospital-acquired pneumonia and intra-abdominal infections from thirteen teaching hospitals in 2013].

OBJECTIVE: To investigate the spectrum and antimicrobial resistance of major pathogensthat causing nosocomial infections in China, 2013. METHODS: Nosocomial cases as well as pathogens causing bloodstream infections (BSI), hospital-acquired pneumonia (HAP) and intra-abdominal infections (IAI) from 13 teaching hospital around China were collected. The minimum inhibitory concentrations (MICs) were determined by the agar dilution method. The CLSI M100-S23 criteria were used for interpretation. RESULTS: Of all cases, 1 022 cases were from BSI, 683 from HAP and 674 from IAI.Escherichia coli and Klebsiella pneumoniae were the most prevalent pathogens causing BSI and IAI while Acinetobacter baumanii (34.6%) and Pseudomonas aeruginosa were dominated in HAP. Tigecycline, imipenem and meropenem exhibited high potency against Enterobacteriaceae and the susceptibilities rates were 95.6%, 94.2%and 95.2% respectively. Enterobacteriaceae demonstrated high resistance against cephalosporins (52.3%) and fluoroquinolones (38.9%) but were susceptible to ß-lactam+inhibitor. Of all the Enterobacteriaceae, 30.5% were ESBLs positive and 4.3% were carbapenem resistant. Acinetobacter baumanii showed low susceptibilities to the microbial agents except for tigecycline (90.5%) and colistin (100%). The rate of carbapenem resistant Acinetobacter baumanii was 76.6%. Amikacin, ciprofloxacin, cefepime and piperacillin/tazobactam showed high antibacterial activity against Pseudomonas aeruginosa with susceptible rate 88.5%, 77.6%, 72.7% and 64.5% respectively. The resistant rate to imipenem and meropenem were 42.1% and 32.2%. All Staphylococcus aureus (166 strains) were susceptible to tigecycline, linezolid, daptomycin and glycopeptides. MRSA accounted for 46.9% of all the Staphylococcus aureus. The prevalence of MRSA in IAI (55.2%) and HAP (54.4%) were higher that that in BSI (35.0%). No Enterococcus strains were found resistant to tigecycline, linezolid and daptomycin. VRE was found in Enterococcus faecium, accounting for 1.9% of all Enterococcus faecium strains. CONCLUSIONS: Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii and Pseudomonas aeruginosa are the most common pathogens causing nosocomial infections. Nosocomial pathogens showed high susceptibilities against tigecycline. For ESBLs-producing Enterobacteriaceae strains, ß-lactam+Inhibitor show high antibacterial activities. Vancomycin, teicoplanin and linezolid exhibit high potency to Staphylococcus aureus and Enterococcus.

Identification and characterization of a novel antifungal compound tubeimoside I targeting cell wall.

Due to fungal diseases that threaten immunocompromised patients, along with the limited availability of antifungal agents, there is an urgent need for new antifungal compounds to treat fungal infections. Here, we aimed to identify potential antifungal drugs from natural products using the fission yeast Schizosaccharomyces pombe as a model organism since it shares many features with some pathogenic fungi. Here, we identified tubeimoside I (TBMS1), an extract from Chinese herbal medicine, that showed strong antifungal activity against S. pombe. To gain insight into the underlying mechanism, we performed transcriptomics analyses of S. pombe cells exposed to TBMS1. A significant proportion of the differential expressed genes were involved in cell wall organization or biogenesis. Additionally, TBMS1 treatment of S. pombe cells resulted in pleiotropic phenotypes, including increased sensitivity to ß-glucanase, enhanced calcineurin activity, translocation of GFP-Prz1 to the nucleus, as well as enhanced dephosphorylation of Prz1, suggesting that TBMS1 disrupted cell wall integrity of S. pombe cells. Notably, calcofluor staining showed that abnormal deposits of cell wall materials were observed in the septum and cell wall of the TBMS1-treated cells, which were further corroborated by electron microscopy analysis. We also found that oxidative stress might be involved in the antifungal action of TBMS1. Moreover, we confirmed the antifungal activities of TBMS1 against several clinical isolates of pathogenic fungi. Collectively, our findings suggest that TBMS1, a novel antifungal compound, exerts its antifungal activity by targeting cell walls, which may pave the way for the development of a new class of antifungals. IMPORTANCE: Fungal infections pose a serious threat to public health and have become an emerging crisis worldwide. The development of new antifungal agents is urgently needed. Here, we identified compound tubeimoside I (TBMS1) for the first time showing strong antifungal activity, and explored the underlying mechanisms of its antifungal action by using the model yeast Schizosaccharomyces pombe. Notably, we presented multiple evidence that TBMS1 exerts its antifungal activity through targeting fungal cell walls. Moreover, we verified the antifungal activities of TBMS1 against several pathogenic fungi. Our work indicated that TBMS1 may serve as a novel antifungal candidate, which provides an important foundation for designing and developing new cell wall-targeting agents for combating life-threatening fungal infections.

Evolutionary accumulation of FKS1 mutations from clinical echinocandin-resistant Candida auris.

INTRODUCTION: Drug resistance to echinocandins, first-line drugs used to treat Candida auris infection, is rapidly emerging. However, the accumulation of mutations in genes other than FKS1 (before an isolate develops to resistance via FKS1 mutations), remains poorly understood. Methods: Four clinical cases and 29 isolates associated with the incremental process of echinocandin resistance were collected and analyzed using antifungal drug susceptibility testing and genome sequencing to assess the evolution of echinocandin resistance. FINDINGS: Six echinocandin minimum inhibitory concentration (MIC)-elevated C. auris strains and seven resistant strains were isolated from the urinary system of patients receiving echinocandin treatment. Meanwhile, phylogenetic analyses illustrated that the echinocandin-resistant strains were closely related to other strains in the same patient. Genomic data revealed that the echinocandin-resistant strains had FKS1 mutations. Furthermore, three categories (ECN-S/E/R) of non-synonymous mutant SNP genes (such as RBR3, IFF6, MKC1, MPH1, RAD2, and MYO1) in C. auris appeared to be associated with the three-stage-evolutionary model of echinocandin resistance in C. glabrata: cell wall stress, drug adaptation, and genetic escape (FKS mutation). INTERPRETATION: Echinocandin-resistant C. auris undergoes spatial and temporal phase changes closely related to echinocandin exposure, particularly in the urinary system. These findings suggest that FKS1 mutations mediate an evolutionary accumulation of echinocandin resistance followed by modulation of chromosome remodelling and DNA repair processes that ultimately lead to FKS1 hot spot mutations and the development of drug resistance. This study provides an in-depth exploration of the molecular pathways involved in the evolution of Candida auris echinocandin resistance.

High prevalence of fluoroquinolone-resistant group B streptococci among clinical isolates in China and predominance of sequence type 19 with serotype III.

A total of 146 group B streptococcus isolates from 8 cities across China belonged to four serotypes. Serotype Ia was more common in children. A high prevalence of resistance was observed for levofloxacin (37.7%), erythromycin (71.2%), clindamycin, (53.4%), and tetracycline (81.5%). The levofloxacin and clindamycin resistances among the 4 serotypes differed significantly. Eighty percent of fluoroquinolone-resistant isolates belonged to the sequence type 19 (ST19)/serotype III clone, with GyrA-ParC-ParE triple substitutions. This clone carried the erm(B), mef(E), and tet(M) genes.

[An analysis of resistance of nosocomial infection pathogens isolated from 13 teaching hospitals in 2011].

OBJECTIVE: To investigate the pathogen profile of nosocomial infection in China, and to survey the susceptibility rates of these pathogens to the clinical common antibiotics. METHODS: The non-repetitive nosocomial pathogens isolated from bloodstream infection (BSI), hospital acquired pneumonia (HAP) and intra-abdominal infection (IAI) and the case data were collected from 13 teaching hospitals in different areas of China and sent to a central laboratory for re-identification and susceptibility testing. The levels of minimal inhibitory concentration (MIC) of the common antibiotics were determined by agar dilution method. The data were analyzed by WHONET 5.6 software. RESULTS: A total of 2103 clinical isolates were collected from January to December 2011, of which gram positive cocci and gram negative organisms accounted for 23.2% and 76.8% respectively. The top three pathogens of BSI were E. coli (31.0%, 243/784), K. pneumoniae (14.8%, 116/784) and S. aureus (10.6%, 83/784). The top three pathogens of HAP were A. baumannii (24.2%, 158/652), P. aeruginosa (23.0%, 150/652) and K. pneumoniae (16.4%, 107/652). The top three pathogens of IAI were E. coli (34.3%, 229/667), E. faecium (13.3%, 89/667) and K. pneumoniae (9.6%, 64/667). Methicillin-resistant S. aureus (MRSA) and coagulase negative Staphylococcus (MRCNS) accounted for 64.4% and 78.1% respectively. The susceptibility rates of Staphylococcus species to tigecycline, vancomycin, teicoplanin and linezolid were all 100%. The prevalence of MRSA in HAP was significantly higher than that in BSI or IAI. The susceptibility rates of Enterococcus species to tigecycline, teicoplanin and linezolid were all 100%. The prevalence of extended-spectrum ß-lactamases (ESBL) was 64.3% in E. coli and 38.3% in K. pneumonia. Against Enterobacteriaceae, the most active agents were as following in order: tigecycline (92.3% - 100%) [except P.mirabilis], meropenem (87.5% - 100%), imipenem (87.5% - 100%) [except M. morganii], amikacin (87.5% - 100%), polymyxin B (75% - 100%) [except S. marcescens, P. mirabilis and M morganii], cefepime (67.8% - 100%), cefoperazone-sulbactam (66.6% - 100%), piperacillin-tazobactam (61.5% - 100%). Carbapenem-resistance Enterobacteriaceae strains emerged. The susceptibility rates of P. aeruginosa to imipenem and meropenem were 66.2% and 72.2%, respectively. The susceptibility rates of A. baumannii to imipenem and meropenem were 27.7% and 25.9%, respectively. The most active agents against A. baumannii were polymyxin B (100%), followed by tigecycline (79.8%) and minocycline (50.4%). The susceptibility rates of P.aeruginosa to antibiotics in BSI were higher than those in HAP and IAI. Susceptibility rates of S. maltophilia to trimethoprim-sulfamethoxazole, minocycline and levofloxacin were about 90% or above. Susceptibility rates of B. cepacia to trimethoprim-sulfamethoxazole, ceftazidime and meropenem were all 100%. Several P.aeruginosa and A. baumannii strains were resistant to all tested antibiotics except polymyxin B. CONCLUSIONS: The pathogen profile is different in different types of infection. The prevalence of multi-drug resistant A. baumannii is high, which is still a key problem of nosocomial infection. Tigecycline remains relatively high activity against gram-positive cocci and gram-negative bacteria (except P. aeruginosa and P. mirabilis) in vitro.

[Antimicrobial resistance of Gram-negative bacilli isolated from 13 teaching hospitals across China].

OBJECTIVE: To explore the antimicrobial resistance of nosocomial Gram-negative bacilli across China. METHODS: A total of 1247 consecutive and non-repetitive Gram-negative bacilli were isolated from 13 Chinese teaching hospitals from March to August 2012. All isolates were sent to a central laboratory for reidentification and susceptibility testing. The minimal inhibitory concentration (MICs) of meropenem and other antibacterial agents were determined by agar dilution method. And the data were analyzed with WHONET-5.6 software. RESULTS: The activity of antimicrobial agents against Enterobacteriaceae was in the following descending order of susceptibility rate: meropenem (97.5%, 849/871) , amikacin (94.5%, 823/871) , imipenem (93.6%, 815/871) , ertapenem (92.9%, 809/871) , piperacillin/tazobactam (89.9%, 783/871) , cefoperazone/sulbactam (83.5%, 727/871) , cefepime (78.1%, 680/871) , polymyxin B (77.0%, 670/871) , cefiazidime (69.6%, 606/871) , levofloxacin (69.2%, 603/871) , ciprofloxacin (63.6%, 554/871) , minocyline (63.1%, 550/871) , ceftriaxone (55.7%, 485/871) , cefotaxime (54.2%, 472/871) and cefoxitin (51.4%, 448/871) . The prevalence of extended-spectrum beta-lactamase (ESBL) was 64.3% (117/182) in Escherichia coli (E. coli) and 32.1% (60/187) in Klebsiella pneumonia (K. pneumoniae) . The sensitivities of E. coli to meropenem and imipenem were 100%. And over 90% of E. coli was sensitive to ertapenem, amikacin, piperacillin/tazobactam and polymyxin B. However, over 60% of E. coli was resistant to ciprofloxacin, levofloxacin, ceftriaxone and cefotaxime. The susceptibility of K. pneumoniae to meropenem, imipenem, amikacin and polymyxin B maintained at over 90%. The activities of antimicrobial agents against E. cloacae, E. aerogenes and Citrobacter freundii were in the following descending order of susceptibility rate: meropenem (96.0%-100%) , imipenem (96.0%-100%) , polymyxin B (95.8%-100%) , amikacin (92.2%-100%) , ertapenem (85.6%-93.3%) , cefepime (77.8%-93.3%) , cefoperazone/sulbactam (78.4%-90.0%) and piperacillin/tazobactam (65.0%-89.8%) . The most susceptible agent against Acinetobacter baumannii (A. baumannii) was polymyxin B (100%) . The susceptibilities of A.baumannii to imipenem, meropenem and minocyline were 37.8% (65/172) , 36.0% (62/172) and 62.8% (108/172) respectively. The most active agents against Pseudomonas aeruginosa (P. aeruginosa) were polymyxin B (97.2%, 173/178) , followed by amikacin (89.3%, 159/178) and cefiazidime (83.7%, 149/178) . Clinical and Laboratory Standards Institute revised P.aeruginosa susceptibility standard in 2012. The sensitivity of piperacillin/tazobactam changed from 83.7% (149/178) to 77.5% (138/178) . The sensitivity of meropenem decreased from 78.1% ( 139/178 ) to 71.3% ( 127/178 ) while that of imipenem declined from 69.7% (124/178) to 59.6% (106/178) . The prevalence of multi-drug resistant A. baumannii and P. aeruginosa were 65.7% (113/172) and 9.0% (16/178) respectively. CONCLUSIONS: Carbapenems remain highly active against Enterobacteriaceae. Increasing resistance of A. baumannii to all antimicrobial agents is noted. New breakpoint to P.aeruginosa has obvious effects on antimicrobial sensitivity.

[Analysis of resistance tendency of bloodstream-infecting pathogens in China].

OBJECTIVE: To investigate the resistance profiles and the trend of bloodstream-infecting pathogens isolated from hospitalized patients during 2004-2010. METHODS: The bloodstream isolates were collected from 18 hospitals in 17 cities. Minimum inhibition concentrations (MIC) were determined using the agar dilution method recommended by CLSI (Clinical and Laboratory Standards Institute), and susceptibility results were analyzed according to the 2011 CLSI guideline. RESULTS: Among the 2004-2005, 2007-2008 and 2009-2010 periods, the proportions of clinical isolates were similar; 43.1% (149 isolates), 34.0% (151 isolates) and 47.5% (776 isolates) for Gram positive strains, 56.9% (197 isolates), 66.0% (293 isolates) and 52.5% (858 isolates) for Gram negative strains, respectively. The isolating rate of MRSA was 54.1% (20/37) in 2007-2008, which was the highest among the 3 periods during 2004 to 2010, while it decreased in 2009-2010 (36.5%, 62/170). The MRCNS proportions were similar across the 3 periods. One (1.8%) vancomycin-resistant Enterococcus faecium and 1 linezolid-resistant Enterococcus faecalis were found. Although the isolating rates of penicillin non-sensitive strains (oral) were similar between 2009-2010 and 2007-2008 [54.5% (6/11) and 53.9% (7/13), respectively], the resistant rates increased from 0% in 2007-2008 to 30.8% (4/13) in 2009-2010. The results were similar according to the non-meningitis criterion (IV), and the susceptibility rates decreased from 100.0% (11 isolates) in 2007-2008 to 84.6% (11/13) in 2009-2010. ESBL-harboring strains in E. coli were similar among the 3 periods during 2004 to 2010 [66.7% (30/45), 73.2% (71/97) and 67.9% (233/343), respectively]. ESBL-producing strains in Klebsilla pnuemoniae decreased year after year, 72.4% (21/29), 50.0% (18/36) and 41.1% (65/158) in 2004-2005, 2007-2008 and 2009-2010, respectively. Except that the sensitive rate of Enterobacter cloacae to ertapenem was 80% (32/40), the sensitive rates of other strains to carbapenems were still above 90% and the resistance rates were less than 5%. Acinetobacter baumannii had the highest multi-drug resistance rate (81.8%, 81/99). One strain (1.0%, 1/99) of Acinetobacter baumannii isolated in 2009-2010 was reported to be pan-resistant. CONCLUSIONS: We are facing a more serious situation of bacterial resistance. Acinetobacter baumannii resistance was most serious, usually with the characteristics of multiple drug resistance, and even pan-resistance. Carbapenems remain to be the most effective against enterobacteriaceae. Strains resistant to novel antibiotics (linezolid and tigecycline) have emerged.

Phenotypic and genetic features of a novel clinically isolated rough morphotype Candida auris.

Introduction: Candida auris is a newly emerging pathogenic fungus of global concern and has been defined by the World Health Organization (WHO) as a member of the critical group of the most health-threatening fungi. Methods: This study reveals and reports for the first time that a rough morphotype C. auris strain causes urinary tract infections in non-intensive care unit (ICU) inpatients. Furthermore, the morphology, the scanning electronmicroscopy (SEM), Whole-genome resequencing and RNA sequencing of C. auris possessing rough morphotype colonies compared to their smooth morphotype counterparts. Results: The newly identified phenotypic variation of C. auris appears round, convex, dry, and burr-like with a rough texture. SEM shows that rough type C. auris has a rough and uneven colony surface with radial wrinkles and irregular spore arrangement. Cells of the rough morphotype C. auris naturally aggregate into clusters with tight connections in the liquid, and it seems that the cell division is incomplete. A genome-wide analysis of the rough type C. auris confirmed its genetic association with the smooth type of C. auris prevalent in China (Shenyang) two years ago; however, single nucleotide polymorphism (SNP) mutations of five genes (ACE2, IFF6, RER2, UTP20, and CaO19.5847) were identified more recently. RNA-seq revealed IFF2/HYR3, DAL5, PSA31, and SIT1 were notably up-regulated, while multiple cell wall-associated genes (ALS1, MNN1, PUL1, DSE1, SCW11, PGA38, RBE1, FGR41, BGLI, GIT3, CEP3, and SAP2) were consistently down-regulated in rough morphotype C. auris. Discussion: The rough phenotypic variation of C. auris is likely to be related to the structural and functional changes in cell wall proteins. This novel rough morphotype C. auris will provide a basis for further studies concerning the evolutionary characteristics of C. auris.

The first rare case of Candida palmioleophila infection reported in China and its genomic evolution in a human host environment.

Introduction: Candida palmioleophila is a rare human pathogenic fungus, which has been poorly characterized at the genome level. In this study, we reported the first fatal case of C. palmioleophila infection in China and investigate the microevolution of C. palmioleophila in the human host environment. Methods: A series of C. palmioleophila stains were collected from the patient at different time points for routine microbial and drug sensitivity testing. The first C. palmioleophila isolate 07202534 was identified by de novo whole genome sequencing. The in vitro and in vivo genetic evolutionary characteristics of C. palmioleophila were discussed based on the analysis of bioinformatics data. Results: The six C. palmioleophila isolates displayed dose-dependent sensitivity to fluconazole. The C. palmioleophila genome contained homologous genes such as CDR1 and MDR1, which were recognized to be related to azole resistance. In addition, amino acid variation was detected at F105L and other important sites of ERG11. In addition, the mean divergence time between C. palmioleophila and Scheffersomyces stipites CBS 6054 was 406.04 million years, indicating that C. palmioleophila originated earlier than its closest relative. In addition, the six strains of C. palmioleophila isolated form the patient had higher homology and fewer mutation sites, which indicated the stability in C. palmioleophila genome. We also found that C. palmioleophila had a wide natural niche and may evolve slowly. Discussion: We believe that this study will contribute to improve our understanding of the genetic evolution, pathogenicity, and drug resistance of C. palmioleophila and will aid in the prevention and control of its spread.

Emergence of Antifungal Resistant Subclades in the Global Predominant Phylogenetic Population of Candida albicans.

Candida albicans remains the most common species causing invasive candidiasis. In this study, we present the population structure of 551 global C. albicans strains. Of these, the antifungal susceptibilities of 370 strains were tested. Specifically, 66.6% of the azole-nonsusceptible (NS)/non-wild-type (NWT) strains that were tested belonged to Clade 1. A phylogenetic analysis, a principal components analysis, the population structure, and a loss of heterozygosity events revealed two nested subclades in Clade 1, namely, Clade 1-R and Clade 1-R-α, that exhibited higher azole-NS/NWT rates (75.0% and 100%, respectively). In contrast, 6.4% (21/326) of the non-Clade 1-R isolates were NS/NWT to at least 1 of 4 azoles. Notably, all of the Clade 1-R-α isolates were pan-azole-NS/NWT that carried unique A114S and Y257H double substitutions in Erg11p and had the overexpression of ABC-type efflux pumps introduced by the substitution A736V in transcript factor Tac1p. It is worth noting that the Clade 1-R and Clade 1-R-α isolates were from different cities that are distributed over a large geographic span. Our study demonstrated the presence of specific phylogenetic subclades that are associated with antifungal resistance among C. albicans Clade 1, which calls for public attention on the monitoring of the future spread of these clones. IMPORTANCE Invasive candidiasis is the most common human fungal disease among hospitalized patients, and Candida albicans is the predominant pathogen. Considering the large number of infected cases and the limited alternative therapies, the azole-resistance of C. albicans brings a huge clinical threat. Here, our study suggested that antifungal resistance in C. albicans could also be associated with phylogenetic lineages. Specifically, it was revealed that more than half of the azole-resistant C. albicans strains belonged to the same clade. Furthermore, two nested subclades of the clade exhibited extremely high azole-resistance. It is worth noting that the isolates of two subclades were from different cities that are distributed over a large geographic span in China. This indicates that the azole-resistant C. albicans subclades may develop into serious public health concerns.