Differential susceptibility to carbapenems due to the AdeABC efflux pump among nosocomial outbreak isolates of Acinetobacter baumannii in a Chinese hospital.

A nosocomial outbreak of carbapenem-resistant Acinetobacter baumannii occurred from February to November 2004 in the surgical intensive care unit (SICU) and the pediatric intensive care unit (PICU) of our hospital. Two separate clones prevailed, the antimicrobial susceptibility profiles of which were different. The PICU isolates produced OXA-23 oxacillinase, whereas no carbapenemases were detected from SICU isolates. No obvious outer membrane protein change was seen. Efflux pump phenotype was detected from SICU isolates. Efflux pump-encoding gene adeB was positive in these isolates and negative in PICU isolates. Through further study, we found that AdeABC efflux system gene contents were common in the SICU isolates. Then we compared the expression level of adeB in resistant and susceptible isolates using quantitative real-time polymerase chain reaction and found that increased expression of AdeABC efflux pump may play an important role in reduced meropenem susceptibility among A. baumannii in the SICU of our hospital.

Prevalence rate of metabolic syndrome and dyslipidemia in a large professional population in Beijing.

The metabolic syndrome (MS) was a clustering of some cardiovascular risk factors, including hypertriglyceridemia, obesity, insulin resistance, glucose intolerance and hypertension. MS patients are at a risk of cardiovascular morbidity and mortality. Although the prevalence of MS in variety of ethnic group has been well documented, limited information is available about the prevalence in Chinese population. The aim of this study is to investigate the prevalence of the MS and dyslipidemia among 16,342 subjects (8801 males and 7541 females) aged 20-90 years in Beijing. 51.9% males and 40.8% females had at least one abnormal serum lipid concentration. The age-standardized prevalence of MS was 13.2% according to Chinese Diabetes Society (CDS) definition of the MS. The prevalence increased with age in both genders. MS was more commonly seen in males than in females (15.7% versus 10.2%). According to the diagnostic criterion, dyslipidemia was observed in 51.9% of males and 40.8% of females, and there was obvious difference between them (P < 0.001). This report on the MS and dyslipidemia from Beijing professional population showed a high prevalence of these disorders. Efforts on promoting healthy diets and physical activity in China should be undertaken.

Prevalence of chronic kidney disease in a middle and old-aged population of Beijing.

BACKGROUND: Chronic kidney disease (CKD) was epidemic worldwide. The prevalence of CKD indicators, including proteinuria, hematuria/uninfectious leukocyturia and reduced GFR, was investigated in the middle and old-aged population of Beijing Shijingshan district. METHODS: Subjects of 2310 aged > or =40 y were enrolled. Their health conditions were taken by questionnaires and physical check-ups. Spot urine albumin to creatinine ratio, spot urine dipstick and microscopy for urine red cell and leukocyte, and serum creatinine was determined. Using simplified Modification of Diet in Renal Disease Study equation estimated GFR assessed renal function. The associations between age, gender, diabetes mellitus, and hypertension, and indicators of kidney damage were examined. RESULTS: Through the questionnaires, the history of diabetes mellitus, hypertension and CKD were found in 28%, 47.1% and 3.6% of subjects, respectively. Albuminuria was detected in 8.4% of subjects, hematuria and uninfectious leukocyturia in 0.7%, and reduced GFR in 4.9%. Approximately 12.9% had at least 1 indicator of CKD. The known rate of CKD in the studied population was 7.1%. Age, diabetes mellitus, hyper fasting blood glucose and hypertension were independently associated with albuminuria; age, gender, hyper uric acid and albuminuria with reduced GFR. When proteinuria and reduced GFR were determined using spot urine dipstick protein > or =25 mg/dl and serum creatinine > or =133 micromol/l, the prevalence of proteinuria and reduced GFR were 4.7% and 0.8%, respectively. CONCLUSION: The prevalence of CKD is common in middle and old-aged population of Beijing, especially in the elderly, but the known rate was relatively low. These findings highlight the clinical and public health importance of CKD.

N-terminal-pro-B-type natriuretic peptide (NT-proBNP): reference range for Chinese apparently healthy people and clinical performance in Chinese elderly patients with heart failure.

BACKGROUND: N-terminal-pro-B-type natriuretic peptide (NT-proBNP) has been found to be a useful marker for the diagnosis of heart failure (HF) and left ventricular systolic dysfunction. We established a reference range for Chinese apparently healthy people based on age and gender and evaluated the clinical performance of NT-proBNP in the diagnosis of asymptomatic and symptomatic HF. METHODS: A group of 442 apparently healthy subjects were enrolled for reference range study. For the clinical performance study, serum NT-proBNP and clinical data were analyzed in 111 elderly patients with HF and 60 normal elderly controls. Serum NT-proBNP was measured by the Roche Elecsys 2010 immunoassay analyzer. RESULTS: NT-proBNP reference range in Chinese people based on age and gender was <83.72 ng/l for men and <131.6 ng/l for women aged 60 years, which were lower than those for western countries. NT-proBNP had a close correlation with New York Heart Association (NYHA) classification (r=0.818) and LVEF (r=-0.636). The ROC curve analysis revealed an AUC of 0.921 for the diagnosis of HF, 0.840 for asymptomatic HF (NYHA I) and 0.951 for symptomatic HF (NYHA II-IV). The optimal cutoff values for detecting HF, asymptomatic HF and symptomatic HF were 102.2, 102.2, and 204.8 ng/l, respectively. NT-proBNP had high positive predictive value (PPV) for the diagnosis of HF (96.8%), asymptomatic HF (90.3%) and symptomatic HF (90.9%), but low negative predictive value (NPV) for diagnosing HF and asymptomatic HF (74.0% and 78.1%, respectively) except symptomatic HF (93.3%). CONCLUSIONS: Chinese people have lower reference range of serum NT-proBNP. NT-proBNP assay has a good clinical performance for the diagnosis of symptomatic HF but is not suitable as a screening test for HF.

[Isolation and identification of Comamonas testosteroni: cloning and overexpression of 3alpha-hydroxysteroid dehydrogenase in E.coli].

OBJECTIVE: To isolate and identify 3alpha-hydroxysteroid dehydrogenase (3alpha-HSD) producing Comamonas testosteroni from soil, and to clone and overexpress 3alpha-HSD in E.coli. METHODS: Samples of pond mud were inoculated into cultural medium with androsterone as sole carbon source. The primary identification was performed according to the morphological observation, biochemical reaction and cultural characterization. To further identify the bacteria, a couple of primers were designed according to the 3alpha-HSD gene of Comamonas testosteroni. An 800 bp fragment containing 3alpha-HSD gene was obtained by PCR amplification. Then the PCR products were inserted into plasmids pET-15b to construct recombinant plasmids pET-15b. Afterwards the host bacteria containing recombinant plasmids pET-15b with proper orientation grew with isopropyl-beta-D-thioglactopyranoside (IPTG) induction. RESULTS: The isolated bacteria which could use androsterone as the sole carbon source had 85% consistency with Comamonas testosteroni. After 5 hours of IPTG induction, a recombinant protein about 29 x10(3) with enzyme activity was overexpressed in the host bacteria E.coli. BL21(DE3) pLysS. This protein could catalyze the dehydrogenization reaction of androsterone (3alpha-hydroxysteroid). CONCLUSION: A strain of Gramjnegative 3alpha-HSD producing Comamonas testosteroni was isolated from pond mud, and recombinant 3alpha-HSD with enzyme activity was overexpressed in E.coli. This work laid good foundation for the purification of recombinant 3alpha-HSD by metal chelate chromatography, and also for the construction of an enzymatic cycling method to measure serum total bile acids with recombinant 3alpha-HSD as the tool enzyme.

Serological diagnosis of infectious mononucleosis by chemiluminescent immunoassay using capsid antigen p18 of Epstein-Barr virus.

BACKGROUND: Infectious mononucleosis is the common clinical manifestation of primary Epstein-Barr virus (EBV) infection in young children. We evaluated a chemiluminescent immunoassay method for the determination of serum anti-viral capsid antigen IgM antibody and its clinical value in the diagnosis of infectious mononucleosis. METHODS: Concentrations of the antibody in serum samples from 187 children measured by chemiluminescent immunoassay were compared with those measured by ELISA. RESULTS: Assessment of technologic quality (methodology) in diagnostic tests demonstrated that sensitivity of CLIA was 0.64 U/ml and the functional sensitivity was <0.9 U/ml. The within-assay and the between-assay imprecisions of different concentrations were all <5%. Recoveries were all in 93-107%. The linear regression equation between expected values and measured values was y=0.0967+1.0093x, correlation coefficient was 0.9996 (p<0.0001). The ROC curve showed that the sensitivity and specificity of the CLIA both were >90%. The area under the curve was 0.992, which was significantly higher than that of ELISA (p<0.05). CONCLUSION: The CLIA was the excellent method for EBV-VCA IgM measurement at present and can improve the clinical diagnosis of infectious mononucleosis.

An enzymatic cycling method for the determination of serum total bile acids with recombinant 3alpha-hydroxysteroid dehydrogenase.

A highly sensitive enzymatic cycling method was developed for the serum total bile acids assay. We constructed a prokaryotic expression system to prepare the recombinant 3alpha-hydroxysteroid dehydrogenase in place of the natural enzyme and for the first time used it in the total bile acids assay. The production rate of thio-NADH correlated with the bile acids concentration and was measured by the change of absorbance at 405/660 nm. The enzymatic cycling method could detect 0.22 micromol/L total bile acids in serum. Within-run and between-run imprecisions were 1.2-3.7% and 2.3-4.8%, respectively. The calibration curve for total bile acids in serum was linear between 0.5 and 180 micromol/L. This method was free from interference by bilirubin, hemoglobin, ascorbate, and lactate dehydrogenase. In conclusion, serum total bile acids could be measured by the enzymatic cycling method with recombinant 3alpha-hydroxysteroid dehydrogenase as the tool enzyme.

Serum lipid concentrations and prevalence of dyslipidemia in a large professional population in Beijing.

BACKGROUND: Lipid abnormalities are major risk factors for premature coronary artery diseases. We investigated serum lipids and the prevalence of dyslipidemia in a professional population in Beijing and compared these data with those obtained in a similar population during 1984-1986. METHODS: We studied 14 963 individuals 20-90 years of age. Health status was determined by questionnaires and physical check-ups. Total cholesterol (TC), LDL-cholesterol (LDL-C), HDL-cholesterol (HDL-C), and total triglycerides (TGs) were measured. TC >5.7 mmol/L, LDL-C >3.6 mmol/L, TGs >1.7 mmol/L, and HDL-C <0.9 mmol/L were defined as abnormal. RESULTS: Mean serum TC, LDL-C, and TG concentrations were increased compared with the values obtained in 1984-1986, with 52.7% of males and 42.9% of females having at least one abnormal lipid concentration. Hypercholesterolemia occurred in 6% of males and 2.8% of females in the younger group (20-39 years) and in 20.2% of males and 38.7% of females in the older group (>60 years). HDL-C was abnormally low in approximately 7% of males and in 1.6% of females. The prevalences of hypercholesterolemia, hypertriglyceridemia, and abnormally low HDL-C, especially the presence of slight hypertriglyceridemia, were higher than in 1984-1986 in all age groups. The increase was most prominent in the middle age group (40-59 years). CONCLUSIONS: Hypercholesterolemia, hypertriglyceridemia, and abnormally low HDL-C have increased considerably over the past 20 years in professional populations in Beijing. Dietary changes and less physical activity resulting from rapid improvements in living conditions may be the causes for the increases. Enhanced preventive measures should be undertaken to modify these situations.

[Safety surveillance and management of specimen associated with SARS in clinical laboratory].

OBJECTIVE: To avoid the staff's infection and environmental contamination, we establish the rules suited for severe infectious disease in our laboratory. METHODS: (1) Enhance the staff's notion of safety, institute a rule for biological safety and make sure the responsibility of safety for everybody. (2) Set up a special laboratory or area for detection of specimens associated with SARS, appoint the staff specially assigned for the task. The approach to environmental cleaning and disinfection in the laboratory is according to the guidance. (3) Laboratory staff should take precaution when entering and leaving laboratory according to the guidance. (4) Collection, transportation, pre-disposal and storage of specimen from patients with SARS for testing should be done in leak-resistant environment. These specimen should be performed in biological safety cabinet. All Clinical waste must be placed in an appropriate leak-resistant biohazard bag or container, labeled and disposed of safely. RESULTS: Since the outbreak of SARS, no staff was infected with SARS in our clinical laboratory. CONCLUSION: Our precaution is feasible and effective. A series of rules ensure the safety for the laboratory staffs and environment.