Epidemiology and antifungal susceptibilities of yeast isolates causing invasive infections across urban Beijing, China.

AIM: To investigate the species distribution and antifungal susceptibility profiles of yeast isolates causing invasive infections across Beijing. MATERIALS & METHODS: A total of 1201 yeast isolates recovered from blood and other sterile body fluids were correctly identified by matrix-assisted laser desorption/ionization TOF MS supplemented by DNA sequencing. Antifungal susceptibility testing was performed according to the Clinical and Laboratory Standards Institute broth microdilution method. RESULTS: Candida (95.5%) remained the most common yeast species isolated; Candida albicans (38.8%) and Candida parapsilosis (22.6%) were the leading species of candidemia. Azole resistances were mainly observed in Candida glabrata and Candida tropicalis isolates. CONCLUSION: This study outlined the epidemiologic data of invasive yeast infections and highlighted the need for continuous monitoring of azole resistances among C. glabrata and C. tropicalis isolates in Beijing.

[Risk factors for acquired multidrug-resistant Acinetobacter baumannii colonization in respiratory intensive care unit].

OBJECTIVE: To determine the risk factors for respiratory intensive care unit (RICU)-acquired colonization of multidrug-resistant Acinetobacter baumannii (MDR-AB). METHODS: From January 2010 to June 2011, active screening was performed to define patients with RICU-acquired colonization of MDR-AB. And environment surveillance was carried out and patient data were collected. Logistic regression was applied to identify the risk factors of RICU-acquired colonization of MDR-AB. RESULTS: Active screening for MDR-AB was performed for 110 patients in RICU and 50 patients turned out to be positive. After eliminating 3 input positive patients, the RICU-acquired colonization rate of MDR-AB was 43.9% (47/107). The environmental contaminated rate of MDR-AB was 66.0% (31/47) for 47 positive patients and 33.9% (19/56) for 56 negative ones (χ(2) = 10.494, P < 0.01). Five risk factors were associated with the colonization of MDR-AB through univariate analysis: consciousness disturbance, use of carbapenems, nasal feeding tube, endotracheal intubation and mechanical ventilation (all P < 0.05). The Logistic regression equation contained 3 risk factors of conscious disturbance, use of carbapenems and mechanical ventilation (OR = 3.412, 3.211, 3.002; 95% CI: 1.165 - 9.992, 1.117 - 9.233, 1.101 - 8.182). CONCLUSION: Three risk factors are independently associated with the RICU-acquired colonization of MDR-AB: consciousness disturbance, use of carbapenems and mechanical ventilation.

[Performance of locked nucleic acid probe real-time polymerase chain reaction in the detection of Aspergillus fumigatus].

OBJECTIVE: To evaluate the performance of locked nucleic acid (LNA) probe Real-time polymerase chain reaction (PCR) in the detection of Aspergillus fumigatus (A. fumigatus). METHODS: All clinically cultured isolates of Aspergillus at our hospital were identified by morphology and DNA sequencing assay. The experimental group consists of A. fumigatus (n = 48) while the control group was made up of A. flavus (n = 55), A. versicolor (n = 16), A. nidulans (n = 10), A. sydowii (n = 5) and A. parasiticus (n = 1). The clinical samples consisted of A. fumigatus sinusitis tissue (n = 20) and bronchoalveolar lavage fluid (n = 1). DNA was extracted from all samples. A. fumigatus ß-tubulin gene was targeted with LNA probe Real-time PCR assay. LNA probe Real-time PCR was evaluated with regards to specificity, efficiency, linear dynamic range in PCR amplification and limits of detection. RESULTS: All clinical samples were positively amplified. The specificity was 100% and the PCR efficiency 98.2%. Linear dynamic range was at least six orders of magnitude and the limit of detection 2.5 pg. CONCLUSION: LNA probe Real-time PCR is a promisingly accurate assay of rapidly detecting A. fumigatus practically and cost-efficiently.

[Correlation factor analysis of pan-drug resistant Acinetobacter baumannii strains in acquired infections].

OBJECTIVE: To explore the clinical factors, drug resistance and molecular epidemiology homologous characteristics of pan-drug resistant Acinetobacter baumannii (PDRAB) in acquired infections and analyze the correlation factor between epidemic characteristics and acquired infections. METHODS: A total of 60 PDRAB strains from nine acquired infections and related clinic data were collected from January 2009 to January 2011. The drug-resistant phenotype was tested by disk diffusion methods. The isolate identification and homology were studied by automation repetitive-element sequence-based (REP)-PCR typing platform from genes and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-TOF MS) from proteins. RESULTS: All strains were resistant to 12 antibiotics except 2 strains to imipenem and meropenem. The strains in this study were divided into 12 types (A-L) by REP-PCR. And 60 strains were also clustered to a-e types by MALDI-TOF-TOF MS. Compared with MALDI-TOF-TOF MS, REP-PCR tended to be more accurate. Breathing machine carriage and cross transmission were the main reasons for a major epidemic outbreak at department of pulmonary medicine from July 2009 to October 2009. Hand transmission of medical care personnel was a key factor for SICU 2010 January to February. The contamination and transmission to environment of PDRAB in nasal pharynx or respiratory tract by superspreader were the main reasons for the other 7 epidemic outbreaks. Department of emergency medicine was the source of acquired infections. CONCLUSION: The key control measures of acquired infections are early identification and isolation of spreader, environment and instrument disinfection, hand washing and rational uses of antibiotics. MALDI-TOF-TOF MS will become a preferred tool of identification and classification of microorganisms because of its simple operation, affordable price and handling rapidity.