Distribution and Antifungal Susceptibility of Candida Species Causing Candidemia in China: An Update From the CHIF-NET Study.

BACKGROUND: Candidemia is the most common, serious fungal infection and Candida antifungal resistance is a challenge. We report recent surveillance of candidemia in China. METHODS: The study encompassed 77 Chinese hospitals over 3 years. Identification of Candida species was by mass spectrometry and DNA sequencing. Antifungal susceptibility was determined using the Clinical and Laboratory Standards Institute broth microdilution method. RESULTS: In total, 4010 isolates were collected from candidemia patients. Although C. albicans was the most common species, non-albicans Candida species accounted for over two-thirds of isolates, predominated C. parapsilosis complex (27.1%), C. tropicalis (18.7%), and C. glabrata complex (12.0%). Most C. albicans and C. parapsilosis complex isolates were susceptible to all antifungal agents (resistance rate <5%). However, there was a decrease in voriconazole susceptibility to C. glabrata sensu stricto over the 3 years and fluconazole resistance rate in C. tropicalis tripled. Amongst less common Candida species, over one-third of C. pelliculosa isolates were coresistant to fluconazole and 5-flucytocine, and >56% of C. haemulonii isolates were multidrug resistance. CONCLUSIONS: Non-albicans Candida species are the predominant cause of candidemia in China. Azole resistance is notable amongst C. tropicalis and C. glabrata. Coresistance and multidrug resistance has emerged in less common Candida species.

Pyogenic liver abscess related to intrahepatic bile duct stones: Difficulties in infectious control and diagnosis of concomitant cholangiocarcinoma.

BACKGROUND AND AIM: Cholangitis, bacteremia, and pyogenic liver abscess (PLA) can be often caused by intrahepatic bile ducts stone (IBDS), which is endemic to South-East Asia. The association between IBDS and cholangiocarcinoma has been well recognized. Concomitant cholangiocarcinoma in the PLA related to IBDS is often missed. METHODS: A case-control study consisting of 64 patients with PLA related to IBDS and 256 control patients with PLA not related to IBDS was used to investigate clinical features of PLA and incidence of concomitant cholangiocarcinoma in patients with PLA related to IBDS. RESULTS: The main imaging manifestations of PLA related to IBDS was cystic-solid lesions and solid lesions. Of seven patients (10.9%) with pathology-proven cholangiocarcinoma in the same area of PLA related to IBDS among 64 patients, only two patients were initially diagnosed as having concomitant cholangiocarcinoma by biopsy, and other five patients diagnosed as acute inflammatory lesion. Within 60 days after onset, the infection-related death rate and recurrence rate in patients with PLA related to IBDS were 12.9% and 20.3%, respectively, whereas in patients with PLA not related to IBDS were 3.9% and 3.1%, respectively. Only 25% of patients with PLA related to IBDS underwent surgery after admission. The main pathogens in PLA patients related to IBDS were Escherichia coli and extended-spectrum beta-lactamase-producing Enterobacteriaceae. CONCLUSIONS: The imaging manifestations of PLA related to IBDS often present cystic-solid or solid lesions. PLA related to IBDS is characterized by high rate of recurrence and infection-related death, difficulty in diagnosis of concomitant cholangicarcinoma.

Biliary diseases as main causes of pyogenic liver abscess caused by extended-spectrum beta-lactamase-producing Enterobacteriaceae.

BACKGROUND & AIMS: Little is known about aetiology and morbidity and clinical characteristics of pyogenic liver abscess caused by extended-spectrum beta-lactamase-producing Enterobacteriaceae. METHODS: An analysis between pyogenic liver abscess patients caused by extended-spectrum beta-lactamase-producing Enterobacteriaceae isolates and those caused by non-extended-spectrum beta-lactamase-producing Enterobacteriaceae was performed. RESULTS: Among 817 pyogenic liver abscess patients, there were 176 patients (21.5%) with pyogenic liver abscess of biliary origin, and 67 pyogenic liver abscess patients (8.2%) caused by extended-spectrum beta-lactamase-producing Enterobacteriaceae isolates (mainly Escherichia coli and Klebsiella pneumoniae). Of 176 pyogenic liver abscess patients related to biliary disorders, there were 48 pyogenic liver abscess patients (27.3%) caused by extended-spectrum beta-lactamase-producing Enterobacteriaceae. Within 67 pyogenic liver abscess patients caused by Enterobacteriaceae expressing extended-spectrum beta-lactamases, the occurrences of 48 pyogenic liver abscess patients (71.6%) were associated with biliary disorders. When compared with pyogenic liver abscess patients caused by non-extended-spectrum beta-lactamase-producing Enterobacteriaceae, there were significantly greater incidences of polymicrobial infections, bacteremia, pulmonary infection, recurrence and death in pyogenic liver abscess patients caused by extended-spectrum beta-lactamase-producing Enterobacteriaceae. Carbapenems remain mainstay drugs against extended-spectrum beta-lactamase-producing E. coli and K. pneumoniae. Independent risk factors for occurrence of pyogenic liver abscess caused by extended-spectrum beta-lactamase-producing Enterobacteriaceae were biliary disorders including extra- and intrahepatic cholangiolithiasis and an abnormal bilioenteric communication between bile and gut, a treatment history of malignancy such as operation and chemotherapy, pulmonary infection, and diabetes mellitus. CONCLUSIONS: Pyogenic liver abscess caused by extended-spectrum beta-lactamase-producing Enterobacteriaceae isolates mainly occurs in patients with biliary disorders or with a treatment history of malignancy. The mainstay of treatment remains carbapenems in combination with adequate aspiration or drainage.

Continual Decline in Azole Susceptibility Rates in Candida tropicalis Over a 9-Year Period in China.

BACKGROUND: There have been reports of increasing azole resistance in Candida tropicalis, especially in the Asia-Pacific region. Here we report on the epidemiology and antifungal susceptibility of C. tropicalis causing invasive candidiasis in China, from a 9-year surveillance study. METHODS: From August 2009 to July 2018, C. tropicalis isolates (n = 3702) were collected from 87 hospitals across China. Species identification was carried out by mass spectrometry or rDNA sequencing. Antifungal susceptibility was determined by Clinical and Laboratory Standards Institute disk diffusion (CHIF-NET10-14, n = 1510) or Sensititre YeastOne (CHIF-NET15-18, n = 2192) methods. RESULTS: Overall, 22.2% (823/3702) of the isolates were resistant to fluconazole, with 90.4% (744/823) being cross-resistant to voriconazole. In addition, 16.9 (370/2192) and 71.7% (1572/2192) of the isolates were of non-wild-type phenotype to itraconazole and posaconazole, respectively. Over the 9 years of surveillance, the fluconazole resistance rate continued to increase, rising from 5.7 (7/122) to 31.8% (236/741), while that for voriconazole was almost the same, rising from 5.7 (7/122) to 29.1% (216/741), with no significant statistical differences across the geographic regions. However, significant difference in fluconazole resistance rate was noted between isolates cultured from blood (27.2%, 489/1799) and those from non-blood (17.6%, 334/1903) specimens (P-value < 0.05), and amongst isolates collected from medical wards (28.1%, 312/1110) versus intensive care units (19.6%, 214/1092) and surgical wards (17.9%, 194/1086) (Bonferroni adjusted P-value < 0.05). Although echinocandin resistance remained low (0.8%, 18/2192) during the surveillance period, it was observed in most administrative regions, and one-third (6/18) of these isolates were simultaneously resistant to fluconazole. CONCLUSION: The continual decrease in the rate of azole susceptibility among C. tropicalis strains has become a nationwide challenge in China, and the emergence of multi-drug resistance could pose further threats. These phenomena call for effective efforts in future interventions.

Risk factors for pneumonia caused by multidrug-resistant Gram-negative bacilli among liver recipients.

Pneumonia caused by multidrug-resistant (MDR) Gram-negative bacilli is associated with a higher mortality rate. The appropriate empiric therapy is based on the understanding of local etiology and MDR pattern. This study was to evaluate the spectrum of Gram-negative bacilli, MDR rate, risk factors and mortality in 475 liver transplantation (LT) recipients. In the first six months after LT, the incidence of bacterial pneumonia was 21.3% (101/475). The overall infectious incidence during the first post-transplant month was 80.2%. The most frequent pneumonia isolates were Enterobacteriaceae, Acinetobacter baumannii, Pseudomonas aeruginosa and Staphylococcus aureus. Gram-negative bacilli accounted for 69.6% of all pneumonia pathogens. Of the main 124 Gram-negative bacilli isolates, MDR rate was 58.9%. Four risk factors for post-LT pneumonia caused by MDR Gram-negative bacilli were LT candidates with grade II-IV encephalopathy (OR 2.275, 95%CI 1.249-4.124, p = 0.006), prolonged duration of endotracheal intubation (OR 8.224, 95%CI 4.276-15.815, p = 0.013), tracheostomy (OR 4.929, 95%CI 1.099-18.308, p = 0.027) and post-LT episode(s) of reoperations (OR 10.597, 95%CI 3.726-30.134, p < 0.001). MDR Gram-negative bacterial pneumonia-related mortality was significantly higher than that because of antibiotic-susceptible bacilli (45.6% vs. 11.4%, p = 0.010). Our data suggest that pneumonia caused by MDR Gram-negative bacilli after LT is common, and associated with the severity of underlying disease, prolonged mechanical ventilation and upper abdominal surgery.

[Surveillance of antimicrobial resistance among nosocomial gram-negative pathogens from 15 teaching hospitals in China in 2005].

OBJECTIVE: To investigate the antimicrobial resistance among the nosocomial gram-negative pathogens from 15 teaching hospitals located in different areas in China in 2005. METHODS: A total of 1927 non-repetitive nosocomial gram-negative pathogens were collected from 15 teaching hospitals in different areas in China and sent to the central lab for reidentification and susceptibility testing. The levels of minimal inhibitory concentration (MIC) of 18 antimicrobial agents were determined by agar dilution method. WHONET 5.4 software was used to analyze the data. RESULTS: The strains of Escherichia coli, Klebsiella pneumoniae, and Proteous mirabilis isolates that did not produce extended spectrum beta lactamases (ESBLs) showed high sensitivity to beta-lactams. The antibiotics with a susceptibility rates over 80% against the strains of Entorobacter cloacae, Enterobacter aerogene, Citrobacter spp, Serratia spp, and Proteous vulgaris producing AmpC enzyme included meropenem, imipenem, and piperacillin-tazobactam, and these 3 drugs showed a susceptibility rate of more than 80% against the ESBL-producing strains of Escherichia coli and Klebsiella pneumoniae. Other antimicrobial agents showing a relatively high activity against Enterobacter spp, Citrobacter spp, Serratia spp and Proteous vulgaris included cefepime (67.3% - 100%), amikacin (67.3% - 95.2%), ceftazidime (52.9% - 100%) and cefoperazone-sulbactam (51.9% - 100%). The susceptibility rate of fluoroquinolones was 34.8% - 36.1% against non-ESBL-producing Escherichia coli and was 13.4% - 17.1% against ESBL-producing isolates. The most active agent against Pseudomonas aeruginosa was polymyxin B (95.6%). The agents with the activity rates of 70% - 80% included meropenem, imipenem, amikacin, and piperacillin-tazobactam. The antibiotic with a high susceptible rate against Acinetobacter baumannii was polymyxin B (98.3%), followed by imipenem (80.8%), meropenem (76.2%), and minocycline (67.4%). The susceptible rates of other agents were all below 60%. The agents with relatively high activity against Stenotrophomonas maltophilia included minocycline (85%), levofloxacin (82.5%), and trimethoprim-sulfamethoxazole (77.5%). The agents with a relatively high activity against Burkholderia cepacia included minocycline (77.2%) and meropenem (61.4%). CONCLUSION: Carbapenem, piperacillin-tazobactam, amikacin and cefepime remained relatively high activity against nosocomial Enterobacteriaceae, Non-fermenting pathogens have lower susceptibility to the antimicrobial agents than before.

[Evaluation of aminoglycoside resistance phenotypes and genotyping of acetyltransferase in Escherichia coli].

OBJECTIVE: To investigate the prevalence of aminoglycoside resistance and genotyping of acetyltransferase in Escherichia coli. METHODS: Resistance phenotypes to 12 antibiotics of 44 Escherichia coli isolates were analyzed using agar dilution method and 3 aminoglycoside resistance genes aac(3)-I, II and aac(6')-I were determined by PCR method. RESULTS: In 44 clinical isolates, the occurrence of ESBLs was 45.45%, resistance rates were discrepant for amikacin (18.18%), gentamicin (56.82%) and tobramycin (61.36%), the prevalence of phenotype TG (tobramycin and gentamicin) indicative of aac(3)-II production and TGA (tobramycin, gentamicin and amikacin) indicative of aac(6')-I production were 36.36% and 18.18%, respectively. The most common aminoglycoside resistance genotype of acetyltransferase was aac(3)-II (52.27%) and aac(6')-I was lower (29.55%), but no aac(3)-I was detected. CONCLUSION: At least 2 acetyltransferase genes exist in this area i.e. aac(3)-II and aac(6')-I.

Inhibition of SATB1 expression in regulatory T cells contributes to hepatitis B virus-related chronic liver inflammation.

Regulatory T cells (Tregs) contribute to the pathogenesis of chronic hepatitis B (CHB). Special AT-rich sequence-binding protein 1 (SATB1) may be a key component of this process. In the present study, Tregs and conventional T cells (Tconvs) were isolated by magnetic cell sorting of peripheral blood from CHB patients (n=57), individuals with resolved hepatitis B virus (HBV) infections (n=15), and healthy controls (n=29). SATB1 expression was studied by reverse transcription-quantitative PCR, flow cytometry and immunofluorescence microscopy, and the correlation of SATB1 expression to the expression of liver inflammation serum markers and the HBV DNA load was assessed. CHB patients showed significantly reduced SATB1 expression in Tregs than healthy controls and individuals with resolved HBV infections. Moreover, SATB1 expression in Tregs was significantly lower than in Tconvs of patients with chronic HBV infection. Serum HBV DNA and liver inflammation markers were inversely correlated to the SATB1 mRNA level in Tregs. Antiviral treatment was accompanied by increased expression of the SATB1 gene in Tregs. Thus, Tregs from CHB patients have reduced levels of SATB1, which is resolved with antiviral therapy. Inhibition of SATB1 expression may impair the hepatic inflammatory response and contribute to HBV persistence.

Typing and characterization of carbapenem-resistant Acinetobacter calcoaceticus-baumannii complex in a Chinese hospital.

This study was designed to investigate the prevalence of carbapenem-resistant Acinetobacter calcoaceticus-baumannii complex (Acb complex) and to type carbapenemases. The relatedness of 45 isolates of carbapenem-resistant Acb complex collected from a clinical setting was analysed by PFGE. The carbapenemases produced by these isolates were typed by IEF, a three-dimensional test, 2-mercaptopropanoic acid inhibition assay, PCR and DNA cloning and sequencing. Results showed that all 45 isolates were resistant to multiple antibiotics including meropenem. The resistance rates to cefoperazone/sulbactam and ampicillin/sulbactam were 2.2 and 6.5%, respectively. About 71.7-78.3% of these isolates were intermediately resistant to cefepime, ceftazidime and cefotaxime. Forty-five isolates were classified into type A (98%) and B (2%) based on their PFGE patterns. Most of type A isolates were from the ICU. Type A was the dominant isolate, including subtypes A1 (22%), A2 (71%), A3 (2%) and A4 (2%). Only one isolate, from the haematology department, belonged to type B. Forty-three isolates (96%) were positive for carbapenemase. One isolate had two bands by IEF, the pIs of which were 6.64 and 7.17. The band with the pI of 6.64 was OXA-23. The other 42 isolates produced two bands with pIs of 6.40 and 7.01 which could not be inhibited by clavulanic acid, cloxacillin or 2-mercaptopropanoic acid. It can be concluded that the prevalent carbapenem-resistant Acb complex isolates from this hospital all had similar beta-lactamase patterns.

[A case-control study on risk factors for nosocomial infection by extended-spectrum beta-lactamases-producing bacteria].

OBJECTIVE: To explore the risk factors for nosocomial infection caused by extended-spectrum beta-lactamases (ESBLs)-producing bacteria in hospitals of Zhejiang province. METHODS: One hundred and eighty-five cases with nosocomial infection (108 men and 77 women, with an average age of 55 +/- 17 years) caused by positive-ESBLs bacteria, including 59 cases of respiratory infection, 71 with urinary infection, ten with blood infection, 30 with wound infection and 59 with other infection, and 77 controls with nosocomial infection (54 men and 23 women, with an average age of 54 +/- 20 years) caused by negative-ESBLs bacteria, including 38 cases of respiratory infection, 20 with urinary infection, six with blood infection, eight with wound infection and five with other infection, from six hospitals in Zhejiang Province were studied during May 1999 to May 2000. Data were analyzed with unconditional logistic regression and principal component analysis (PCA). RESULTS: Multivariate unconditional logistic regression analysis showed that the independent risk factors for nosocomial infection were use of the third generation cephalosporins for more than three days (odds ratio, OR 4.52, 95% confidence interval of OR 2.30 - 8.89), combined use of antibiotics (OR 2.86, 95% CI 1.51 - 5.43), use of quinolones for more than three days (OR 2.44, 95% CI 1.18 - 5.04), use of adrenal cortical hormone (OR 2.16, 95% CI 1.08 - 4.31) and oxygen inhalation (OR 2.56, 95% CI 1.14 - 5.72). Five principal components were extracted from the 14 risk factors for nosocomial infection with ESBLs-producing bacteria by principal component analysis, with a contribution of cumulative variance of 60.2%, and arranged in an order as follows, use of ventilator, tracheal intubation or tracheotomy, oxygen inhalation, retaining needle in vein, indwelling urethral catheter, use of the third generation cephalosporins over three days, hospitalization over ten days, use of quinolones over three days, combined use of antibiotics, use of aminoglycosides antibiotic over a week, use of adrenal cortical hormone, catheterized examination and prophylactic use of antibiotics. CONCLUSIONS: Nosocomial infection with ESBLs-producing bacteria could attribute to multiple factors, mainly to invasive manipulation and use of antibiotics.

[Emergence of novel variants of gyrA, parC, qnrS genes in multi-drug resistant Klebsiella caused pneumonia].

OBJECTIVE: To investigate the resistant mechanism of quinolones on multi-drug resistant Klebsiella caused pneumonia (MDR-KPN). METHODS: From August 2008 to May 2010, 47 strains of MDR-KPN were collected from 6 hospitals in Hangzhou and Huzhou in Zhejiang province in China. Drug target genes to quinolones (gyrA, parC) and quinolone-resistance genes mediated by mobile genetic elements [qnrA, qnrB, qnrS, aac (6')-Ib-cr, qepA] were analyzed by PCR and verified by DNA sequencing. RESULTS: Positive results were found in 47 strains of MDR-KPN, 43 strains (91.5%) of gyrA mutation, 40 strains (85.1%) of parC mutation, 3 strains (6.4%) of qnrB2, 1 strain (2.1%) of qnrB 4, 8 strains (17.0%) of qnrS 1, 5 strains (10.6%) of qnrS 4, 2 strains (4.3%) of aac (6')-Ib-cr respectively. Moreover, 5 novel variants of gyrA (GenBank accession number: JN811952, JN811953, JN811954, JN811955, JN811956), 5 novel variants of parC (GenBank accession number: JN817432, JN817433, JN817434, JN817435, JN817436) were also identified. In addition, qnrS4 (GenBank accession number: JN836269) appeared to be the novel variants of qnrS. CONCLUSION: Quinolone-resistance-determining region played a key role on the resistance to quinolones in this group of MDR-KPN, and quinolone-resistance genes mediated by mobile genetic elements [qnrB2, qnrB4, qnrS1, qnrS4, aac (6')-Ib-cr] showed positive in some parts of the strains. This was the first report on emergence of qnrS4 in the world.

Coagulase-negative staphylococcus and enterococcus as predominant pathogens in liver transplant recipients with Gram-positive coccal bacteremia.

BACKGROUND: Gram-positive bacteria such as Staphylococcus aureus have been a common cause of infection among liver transplant (LT) recipients in recent decades. The understanding of local epidemiology and its evolving trends with regard to pathogenic spectra and antibiotic susceptibility is beneficial to prophylactic and empiric treatment for LT recipients. This study aimed to investigate etiology, timing, antibiotic susceptibility and risk factors for multidrug resistant (MDR) Gram-positive coccal bacteremia after LT. METHODS: A cohort analysis of prospectively recorded data was performed to investigate etiologies, timing, antibiotic susceptibility and risk factors for MDR Gram-positive coccal bacteremia in 475 LT recipients. RESULTS: In 475 LT recipients in the first six months after LT, there were a total of 98 episodes of bacteremia caused by Gram-positive cocci in 82 (17%) patients. Seventy-five (77%) bacteremic episodes occurred in the first post-LT month. The most frequent Gram-positive cocci were methicillin-resistant coagulase-negative staphylococcus (CoNS, 46 isolates), methicillin-resistant Staphylococcus aureus (MRSA, 13) and enterococcus (34, E. faecium 30, E. faecalis 4). In all Gram-positive bacteremic isolates, 59 of 98 (60%) were MDR. Gram-positive coccal bacteremia and MDR Gram-positive coccal bacteremia predominantly occurred in patients with acute severe exacerbation of chronic hepatitis B and with fulminant/subfulminant hepatitis. Four independent risk factors for development of bacteremia caused by MDR Gram-positive coccus were: LT candidates with encephalopathy grades II - IV (P = 0.013, OR: 16.253, 95%CI: 1.822 - 144.995), pre-LT use of empirical antibiotics (P = 0.018, OR: 1.029, 95%CI: 1.002 - 1.057), post-LT urinary tract infections (P < 0.001, OR: 20.340, 95%CI: 4.135 - 100.048) and abdominal infection (P = 0.004, OR: 2.820, 95%CI: 1.122 - 10.114). The main infectious manifestations were coinfections due to gram-positive cocci and gram-negative bacilli. CONCLUSIONS: Methicillin-resistant CoNS and enterococci are predominant pathogens among LT recipients with Gram-positive coccal bacteremia. Occurrences of Gram-positive coccal bacteremia may be associated with the severity of illness in the perioperative stage.