Rapid Identification and Subtyping of Enterobacter cloacae Clinical Isolates Using Peptide Mass Fingerprinting.

OBJECTIVE: To establish a domestic database of Enterobacteria cloacae (E. cloacae), and improve the identification efficiency using peptide mass fingerprinting. METHODS: Peptide mass fingerprinting was used for the identification and subtyping of E. cloacae. Eighty-seven strains, identified based on hsp60 genotyping, were used to construct and evaluate a new reference database. RESULTS: Compared with the original reference database, the identification efficiency and accuracy of the new reference database was greatly improved at the species level. The first super reference database for E. cloacae identification was also constructed and evaluated. Based on the super reference database and the main spectra projection dendrogram, E. cloacae strains were divided into two clades. CONCLUSION: Peptide mass fingerprinting is a powerful method to identify and subtype E. cloacae, and the use of this method will allow us to obtain more information to understand the heterogeneous organism E. cloacae.

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.