Molecular identification, antifungal susceptibility, and resistance mechanisms of pathogenic yeasts from the China antifungal resistance surveillance trial (CARST-fungi) study.

To have a comprehensive understanding of epidemiology and antifungal susceptibilities in pathogenic yeasts, the China Antifungal Resistance Surveillance Trial (CARST-fungi) study was conducted. All yeast isolates were identified by ribosomal DNA sequencing. Antifungal susceptibilities were performed using CLSI M27-A4 broth microdilution method. Sequence and expression level of resistant-related genes in resistant/non-wide-type (NWT) Candida isolates were analyzed. Totally 269 nonduplicate yeast isolates from 261 patients were collected. About half of the yeast isolates (127, 47.2%) were recovered from blood, followed by ascetic fluid (46, 17.1%). C. albicans remained the most prevalent (120, 44.6%), followed by C. parapsilosis complex (50, 18.6%), C. tropicalis (40, 14.9%), and C. glabrata (36, 13.4%). Fourteen (11.7%) C. albicans isolates and 1 (2.0%) C. parapsilosis isolate were resistant/NWT to triazoles. Only 42.5% (17/40) C. tropicalis were susceptible/WT to all the triazoles, with 19 (47.5%) isolates NWT to posaconazole and 8 (20%) cross-resistant to triazoles. Among C. glabrata, 20 (55.6%) and 8 (22.2%) isolates were resistant/NWT to voriconazole and posaconazole, respectively, and 4 (10.3%) isolates were cross-resistant to triazoles. Isavuconazole was the most active triazole against common Candida isolates. Except for 2 isolates of C. glabrata cross-resistant to echinocandins which were also NWT to POS and defined as multidrug-resistant, echinocandins exhibit good activity against common Candida species. All isolates were WT to AMB. For less common species, Rhodotorula mucilaginosa exhibited high MICs to echinocandins and FLC, and 1 isolate of Trichosporon asahii showed high MICs to all the antifungals except AMB. Among triazole-resistant Candida isolates, ERG11 mutations were detected in 10/14 C. albicans and 6/23 C. tropicalis, while 21/23 C. tropicalis showed MDR1 overexpression. Overexpression of CDR1, CDR2, and SNQ2 exhibited in 14, 13, and 8 of 25 triazole-resistant C. glabrata isolates, with 5 isolates harboring PDR1 mutations and 2 echinocandins-resistant isolates harboring S663P mutation in FKS2. Overall, the CARST-fungi study demonstrated that although C. albicans remain the most predominant species, non-C. albicans species accounted for a high proportion. Triazole-resistance is notable among C. tropicalis and C. glabrata. Multidrug-resistant isolates of C. glabrata and less common yeast have been emerging.

A multicenter investigation of 2,773 cases of bloodstream infections based on China antimicrobial surveillance network (CHINET).

Background: Bloodstream infections (BSIs), especially hospital-acquired BSIs, are a major cause of morbidity and mortality. However, the details about the pathogens and antimicrobial resistance profile of BSIs across China are still lacking. Methods: An investigation was conducted in 10 large teaching hospitals from seven geographic regions across China in 2016 based on China Antimicrobial Surveillance Network (CHINET) to profile the clinical and etiological features of BSIs. Results: A total of 2,773 cases of BSIs were identified, a majority (97.3%) of which were monomicrobial. Overall, 38.4% (1,065/2,773) were community-acquired BSIs (CABSIs), and 61.6% (1,708/2,773) were hospital-acquired BSIs (HABSIs). Of the 2,861 pathogenic BSI isolates, 67.5% were Gram-negative bacteria, 29.6% were Gram-positive bacteria, and 2.9% were fungi. The top BSI pathogens were Escherichia coli, Klebsiella pneumoniae, coagulase-negative Staphylococci (CNS), Staphylococcus aureus, Enterococci, and Acinetobacter baumannii. Escherichia coli and K. pneumoniae isolates showed low susceptibility to penicillins, cephalosporins (except ceftazidime and cefepime), and ampicillin-sulbactam (13.1%-43.4% susceptible); moderate susceptibility (about 60% susceptible) to ceftazidime, cefepime, and aztreonam; and high susceptibility (>90%) to ß-lactam/ß-lactamase inhibitor combinations other than ampicillin-sulbactam, except K. pneumoniae strains to piperacillin-tazobactam (59.2% susceptible). HABSIs were associated with significantly higher prevalence of carbapenem-resistant and extended-spectrum ß-lactamases-producing K. pneumoniae, methicillin-resistant S. aureus, methicillin-resistant CNS, and ampicillin-resistant Enterococci than CABSIs. Overall, 42.0% of the BSI due to S. aureus strains were resistant to methicillin. Conclusions: The findings about BSIs in teaching hospitals across China add more scientific evidence to inform the appropriate management of the disease.

Investigation of an outbreak of Burkholderia cepacia infection caused by drug contamination in a tertiary hospital in China.

BACKGROUND: Contamination of drugs used in minimally invasive treatment may to lead to infection outbreaks and catastrophic public health events that require prompt detection and control. Our aim was to investigate the outbreak of Burkholderia cepacia infection and its source in a tertiary care, general hospital in Beijing, China. METHODS: We investigated the outbreak of B cepacia infection from January 2017 to March 2018. The investigation included a detailed review of all cases, and field investigations. Environmental and product cultures were performed at the microbiology laboratory in the hospital. Isolates were evaluated for molecular relatedness using pulsed-field gel electrophoresis performed in an independent laboratory. RESULTS: In total, 9 patients were infected from November 2017 to March 2018, and all patients had undergone the following surgeries: transurethral resection of the prostate (n = 4), perineal prostate biopsy (n = 2), transurethral resection of bladder tumors (n = 2), and ureteroscopy (n = 1). B cepacia was isolated from the urine of 9 patients, blood of 2 patients, grilles used for puncturing, and 2 samples in 1 batch of analgesic gels. Pulsed-field gel electrophoresis confirmed that the isolates from the patients and gels were homologous. CONCLUSIONS: Our investigation revealed that the outbreak of B cepacia infection was caused by drug contamination.

Predictability of Phenotype in Relation to Common ß-Lactam Resistance Mechanisms in Escherichia coli and Klebsiella pneumoniae.

The minimal concentration of antibiotic required to inhibit the growth of different isolates of a given species with no acquired resistance mechanisms has a normal distribution. We have previously shown that the presence or absence of transmissible antibiotic resistance genes has excellent predictive power for phenotype. In this study, we analyzed the distribution of six ß-lactam antibiotic susceptibility phenotypes associated with commonly acquired resistance genes in Enterobacteriaceae in Sydney, Australia. Escherichia coli (n = 200) and Klebsiella pneumoniae (n = 178) clinical isolates, with relevant transmissible resistance genes (blaTEM, n = 33; plasmid AmpC, n = 69; extended-spectrum ß-lactamase [ESBL], n = 116; and carbapenemase, n = 100), were characterized. A group of 60 isolates with no phenotypic resistance to any antibiotics tested and carrying none of the important ß-lactamase genes served as comparators. The MICs for all drug-bacterium combinations had a normal distribution, varying only in the presence of additional genes relevant to the phenotype or, for ertapenem resistance in K. pneumoniae, with a loss or change in the outer membrane porin protein OmpK36. We demonstrated mutations in ompK36 or absence of OmpK36 in all isolates in which reduced susceptibility to ertapenem (MIC, >1 mg/liter) was evident. Ertapenem nonsusceptibility in K. pneumoniae was most common in the context of an OmpK36 variant with an ESBL or AmpC gene. Surveillance strategies to define appropriate antimicrobial therapies should include genotype-phenotype relationships for all major transmissible resistance genes and the characterization of mutations in relevant porins in organisms, like K. pneumoniae.

Prevalence and clinical prognosis of heteroresistant vancomycin-intermediate Staphylococcus aureus in a tertiary care center in China.

BACKGROUND: The emergence of heteroresistant vancomycin-intermediate Staphylococcus aureus (hVISA) is increasingly challenging the methods for detection in diagnostic microbiology laboratories. However, the report of hVISA is rare in China. This study summarizes the prevalence and clinical features associated with hVISA infections at our institution and the local impact they have on clinical outcome. METHODS: A total of 122 methicillin-resistant Staphylococcus aureus (MRSA) isolates which were of the causative pathogens were collected. One hundred and two patients for whom we had full information of MRSA pneumonia were included. Isolates of MRSA were collected using PCR to detect the mecA gene. Both Etest and macro Etest were performed to screen for hVISA. The Staphylococcal chromosome cassette mec (SCCmec) types were determined by multiplex PCR strategy. Logistic regression analysis was used to determine the risk factors. RESULTS: Among the 122 MRSA isolates collected, 25 (20.5%) strains were identified as hVISA. There were 119 (97.5%) SCCmec III isolates, two (1.6%) SCCmec II isolates, and one (0.8%) SCCmec V isolate. The 30-day mortality of MRSA-hospital acquired pneumonia (HAP) was 37.3%, and 62.5% for hVISA-HAP. Vancomycin treatment was the independent risk factor of hVISA. Factors independently associated with 30-day mortality in all patients were acute physiology and Chronic Health Evaluation (APACHE) II score >20, multiple lobe lesions, and creatinine clearance rate (CCR) < 15 ml/min. CONCLUSIONS: The prevalence of hVISA is 20.5% at our institution. hVISA-HAP patients had a poor clinical outcome. Vancomycin treatment was the independent predictors for hVISA infection. Factors independently associated with 30-day mortality in all patients were APACHE II score > 20, multiple lobe lesions and CCR < 15 ml/min.

[Changes of pathogens and susceptibility to antibiotics in hematology ward from years 2001 to 2005].

The purpose of this study was to determine the changes of pathogens in hematological ward and susceptibility of patients received chemotherapy to antibiotics. The pathogens were taken from blood, urine and sputum of patients who accepted chemotherapy from years 2001 to 2005, then were isolated and identified. The susceptibility test was performed by disk diffusion method. The results showed that the total of 418 strains were detected. Gram-negative bacteria were the most common of nosocomial infection. Pseudomonas aeruginosa, Enterobacter cloacae, E. coli account for the most of Gram negative- bacteria infection and most resistant to broad-spectrum penicillin, Acinetobacter baumannii showed a trend of increase. The ratios of gram positive bacteria and fungi were increased slowly, mainly as Enterococcus and Candida. Enterococcus is the most common cause of Gram-positive bacterial infection. Vancomycin resistance did not occur. It is concluded that Gram-negative bacteria are main cause of nosocomial infection in patients with hematological malignancies. Gram positive bacteria and fungi had been more frequent. Strains resistant to antimicrobial agents increase.