Nosocomial bloodstream infection in patients caused by Staphylococcus aureus: drug susceptibility, outcome, and risk factors for hospital mortality / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Previous studies have different viewpoints about the clinical impact of methicillin resistance on mortality of hospital-acquired bloodstream infection (BSI) patients with Staphylococcus aureus (S. aureus). The objective of this study was to investigate the mortality of hospital-acquired BSI with S. aureus in a military hospital and analyze the risk factors for the hospital mortality.</p><p><b>METHODS</b>A retrospective cohort study was performed in patients admitted to the biggest military tertiary teaching hospital in China between January 2006 and May 2011. All included patients had clinically significant nosocomial BSI with S. aureus. Multivariate Logistic regression analysis was used to identify the risk factors for hospital mortality of patients with S. aureus BSI.</p><p><b>RESULTS</b>One hundred and eighteen patients of more than one year old were identified as clinically and microbiologically confirmed nosocomial bacteraemia due to S. aureus, and 75 out of 118 patients were infected with methicillin-resistant S. aureus (MRSA). The overall mortality of nosocomial S. aureus BSI was 28.0%. Methicillin resistance in S. aureus bacteremia was associated with significant increase in the length of hospitalization and high proportion of inappropriate empirical antibiotic treatment. After Logistic regression analysis, the severity of clinical manifestations (APACHE II score) (odds ratio (OR) 1.22, 95% confidence interval (CI) 1.12 - 1.34) and inadequacy of empirical antimicrobial therapy (OR 0.25, 95%CI 0.09 - 0.69) remained as risk factors for hospital mortality.</p><p><b>CONCLUSIONS</b>Nosocomial S. aureus BSI was associated with high in-hospital mortality. Methicillin resistance in S. aureus has no significant impact on the outcome of patients with staphylococcal bacteremia. Proper empirical antimicrobial therapy is very important to the prognosis.</p>

Viral shedding in Chinese young adults with mild 2009 H1N1 influenza / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The duration of viral shedding and the transmission of 2009 H1N1 influenza among individuals, especially among the younger population with mild illness, are not well understood now. The aim of this study was to determine the viral shedding of the young adult patients with mild 2009 H1N1 influenza in China.</p><p><b>METHODS</b>From September 2009 to January 2010, the clinical data and serial nasopharyngeal swabs of 67 patients with 2009 H1N1 influenza and 37 patients with seasonal influenza aged from 18 years to 35 years were collected. The nasopharyngeal swab samples were detected by real time RT-PCR to determine the viral shedding. All the patients did not receive the antiviral therapy but Chinese medicine for detoxicating.</p><p><b>RESULTS</b>Among the patients with H1N1 virus infection, 82.1% (55/67) patients presented with fever symptom, while more patients with high fever (≥ 39°C) were found in seasonal influenza patients (P < 0.05). For the H1N1 patients, the median interval between the symptom onset and the undetectable RNA was six days (4 - 10 days). But viral shedding was still found in 31.3% patients after 7 days following illness onset. The median interval between disappearance of fever and an undetectable viral RNA level was three days (2 - 8 days), and 17.9% patients were found to be viral shedding 6 days later after normalization of body temperature. For the seasonal influenza patients, 94.6% patients were detected out viral RNA within 7 days. The median interval of seasonal influenza between the symptom onset and the undetectable RNA was four days (3 - 8 days). The median interval between disappearance of fever and an undetectable viral RNA level was three days (2 - 6 days).</p><p><b>CONCLUSION</b>It suggests that 7 days isolation period from the illness onset or 24 hours after the resolution of fever and respiratory symptoms are not long enough to cut off the transmission among Chinese young adults with mild illness.</p>

Genotyping on 47 Staphylococcus aureus strains associated with bloodstream infection / 中华流行病学杂志

Objective To investigate the molecular epidemiological characteristics of Staphylococcus aureus associated with bloodstream infection in hospital. Methods 47 Staphylococcus aureus strains isolated from bloodstream in PLA General Hospital were collected from January 2006 to December 2008. Susceptibility of the strains to 11 antimicrobial agents was detected and DNA homology of them was analyzed with Rep-based DiversiLab~(TM) Microbial Typing System. Panton-Valentine leukocidin (PVL)gene was determined by PCR. For methicillin-resistant Staphylococcus aureus (MRSA) strains,the genotypes of SCCmec were determined and ST239 clone was screened with multiplex PCR. Multilocus sequence typing (MLST) was used to determine the STs of the selected isolates. Results In the 47 Staphylococcus aureus isolated from blood,methicillin-resistant strains accounted for 51.1%,all belonged to SCCmec Ⅲ type,with only 2 pvl gene positive strains identified. 12 different patterns (A-L) were found among 47 strains with Rep-PCR. All MRSA strains clustered in the A and B subtypes. Conclusion Most MRSA strains isolated from blood in PLA General Hospital belonged to ST239-MRSA-SCCmec Ⅲ clone. DiversiLab~(TM) Microbial Typing System could provide a rapid and effective method to investigate the molecular epidemiological characteristics of Staphylococcus aureus in the hospital settings.

Colloidal gold and dot-ELISA rapid tests for screening influenza A virus / 南方医科大学学报

<p><b>OBJECTIVE</b>To evaluate the diagnostic efficiency of colloidal gold and dot ELISA rapid tests in clinical screening of influenza A virus.</p><p><b>METHODS</b>The pharyngeal swabs were collected from 297 outpatients suspected of influenza between June and October, 2009 for detection with colloid gold and dot ELISA rapid test, with real-time PCR as the golden methods. The discrepant results of colloid gold and dot ELISA methods were confirmed by sequencing, and the diagnostic efficiency of the two methods was evaluated.</p><p><b>RESULTS</b>Among the 166 samples with influenza A virus infection as confirmed by real-time PCR and sequencing, the diagnostic sensitivity of dot ELISA and colloid gold methods was 54.82% (91/166) and 4.22% (7/166), respectively. The total concordance rate with PCR was 66.67% (Kappa value of 0.35). Among the 133 samples negative for influenza A virus, the specificity of dot ELISA and colloid gold methods was 81.68% (107/131) and 98.47% (129/131), respectively, with a total concordance rate with PCR of 45.79% (Kappa value 0.02). Of the 99 H1N1 influenza samples confirmed by real-time PCR, the detection rate of dot ELISA was 67.3%, whereas that of colloid gold was 5.1%. Out of the 107 dot ELISA-positive but colloid gold-negative samples, 84 were confirmed to be influenza A virus-positive by real-time PCR and sequencing. One sample negative for dot ELISA but positive for colloid gold test was confirmed to be influenza A virus-negative. The detection rate and diagnostic concordance rate for influenza A virus by dot ELISA were significantly higher than those of colloid gold (P<0.05).</p><p><b>CONCLUSION</b>Dot ELISA is better than colloid gold in influenza A virus detection and shows great prospect in clinical screening.</p>

Study on the molecular characteristics of multidrug-resistant Acinetobacter baumannii / 中华流行病学杂志

Objecfive To investigate antibiotic resistance,carbapenemase genotype and the molecular epidemiology of multidrug-resistant Acinetobacter baumannii (Aba) collected from 3 military hospitals in China.Methotis The minimum inhibitory concentrations (MIC) were examined by ager dilution method.Genotypes of carbapenemases were amplified by multiplex PCR and its products were sequenced.PCR was used to detect per gene,Homology of the resistant isolates was analyzed by pulse-field gel electrophoresis(PFGE).Results Among the 64 MDRA strains,78.1%(50)strains possessed blaOXA-23 gene,89.1%(57) carried Class 1 integrase gene,39.1% (25) with blaPER-1 gene,and 1 strain with blaOXA-58-like gene.PFGE showed that 13(A,B,C,D,E genotype) different clones were identified in these strains.A,B,and U clones were the predominant clones in three hospitals,respectitively.Conclusion OutbreaEs of muitidrug-rcsistant Aba occurred at 3 military hospitals with the most prevalent carbapenemase as OXA-23 enzyme.OXA-58 type of carbapenemase and per-1 in Aba were also isolated.

Transmission and molecular characteristics of carbapenem-resistant Acinetobacter baumannii / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the mode of transmission and molecular characteristics on carbapenem-resistant Acinetobacter baumannii strain. Strains were isolated from different parts of samples in various patients.</p><p><b>METHODS</b>Clinical information of carbapenem-resistant Acinetobacter baumannii isolates were stored and analyzed by WHONET 5.4 software. The transmission and pathopoiesis of the strains were learned through case file review. Genotypes of isolates were identified by pulse-field gel electrophoresis (PFGE) and genes of carbapenemase were detected by multiple PCR, in order to find molecular characteristics and relatedness between strains.</p><p><b>RESULTS</b>29 stains of Acinetobacter baumannii resistant to carbapenem were isolated from 2 or more kinds of samples among 13 patients'. Two genotypes were identified by PFGE: genotype A was obtained from 22 isolates in 11 patients and genotype B was obtained from 7 isolates in 4 patients. PCR amplification showed that all strains possessed OXA-23 gene except 1, and all strains possessed Integrase gene I except 3.</p><p><b>CONCLUSION</b>There were 2 different genotypes from 29 strains of carbapenem-resistant Acinetobacter baumannii with Genotype A as the main type. OXA-23 carbapenemase gene and integrase gene I were detected from most of the isolates. All the strains could be easily transmitted in the body of the patients and among patients, hence becoming the epidemic pathogen of iatrogenic infection.</p>