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>

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>

Quantitative PCR for diagnosis of invasive fungal infections in patients with hematologic malignancies / 中国实验血液学杂志

This study was aimed to establish the method of quantitative PCR (q-PCR) of fungi in peripheral blood for diagnosis of invasive fungal infections in patients with hematologic malignancies, and to preliminarily assess the diagnostic value of this method. The 18S rDNA-ITS1 area of high consensus sequence of fungi was selected to design primer and probe, the DNA of fungal species was extracted and q-PCR was performed to evaluate the sensitivity and specificity of the primer and probe. The standard product of fungal DNA was prepared by using pGEM-T plasmid and the fungal DNA in blood of patients was quantitatively detected. The results showed that the positive was found in 12 Aspergillus and 14 Candida species according to q-PCR detection, while there was no significant difference of fungal distribution between plasma, mononuclear cells and leukocytes (p<0.05). Receiver-operating characteristic analysis of q-PCR showed that the cut-off value for clinical diagnosis of invasive fungal infection was 8 copies/ml whole blood, its sensitivity, specificity, positive and negative predictive value and kappa were 0.84, 0.9, 0.955, 0.692 and 0.679 respectively. It is concluded that the fungal q-PCR assay may be used as an early diagnostic method for invasive fungal infections in patients with hematologic malignancies.

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.

Current approaches to diagnosis and treatment of invasive fungal infection in HSCT recipients / 中国实验血液学杂志

Invasive fungal infections (IFI) are a kind of the most severe complications after hematopoietic stem cell transplantation (HSCT), Candida and Aspergillus are common causes. Because of immunosuppressive therapy, ablative conditioning regimen, acute or chronic graft-versus-host disease, long-term treatment of broad-spectrum antibiotics and cytomegalovirus infection, IFI has increased in the past few years. Invasive mould infection is a major cause of morbidity and mortality in HSCT recipients. Methods for early diagnosis of IFI include clinical and laboratory examinations, as well as characteristic radiography. Voriconazole is the first-line antifungal agent for prevention of IFI. Combination therapy of two antifungal compounds such as azoles or amphotericin B with echinocandins have shown a good effectiveness and may be a promising future strategy for antifungal treatment. In this review, the early diagnosis and treatment of IFI in HSCT recipients are summarized. As for early diagnosis of IFI, the laboratory diagnosis techniques such as GM test, G test and PCR techniques are discussed. As for prophylaxis and treatment of IFI, the prophylaxis treatment, empirical treatment, preemptive treatment, targeted treatment, combined treatment and immunologic treatment are discussed.

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>

Study on CMY-2 AmpC ?-lactamase mediated by plasmid in Escherichia coli / 中华检验医学杂志

Objective To study the AmpC beta-lactarnase and its genotype mediated by plasmid in Escherichia coli.Methods AmpC beta-lactamase was detected based on that AmpC beta-laetamase can be inhibited by 3-aminophenylboronic acid(APB).MIC was ehecked by agar dilution method.Conjugation test was used to check the transfer of ampC gene.Gene chip and PCR were used to detect ampC gene.The amplified ampC gene were sequenced and analyzed by EMBOSS software.The molecular epidemiology of clinical isolates was investigated by Enterbacterial repetitive intergenic consensus(ERIC)typing method.Results In 74 strains of Escherichia coli insusceptible to cefoxtin,AmpC beta-lactamase was positive in 33 strains.8 strains possessed AmpC beta-lactamase of CIT group by gene chip and 8 transconjugants were obtained by conjugation test.CMY type ampC gene could be further amplified by specific CMY gene primers from both 8 clinical isolates of E.coli and plasmids extracted from 8 transconjugants.CMY-2 type ampC gene was found by sequencing(accession number DQ823449).The most transconjugants displayed similar MIC value(intermediate or resistant).ERIC genotyping showed 6 out of 8 isolates with CMY-2 ampC gene derived from different resource.Conclusion CMY-2 AmpC beta- lactamase mediated by plasmid could be detected in E.coli isolates from patients in the General Hospital of People Liberation Army,Beijing.The plasmid carried ampC gene could mediate multi-drug resistance.

Detection of antifungal agent activity against the filamentous fungi by Etest / 中华检验医学杂志

Objective To investigate the susceptibility of amphotericin B,itroconazol and voriconazole against filamentous fungi.Methods Etest was used to determine the MIC of amphotericin B, itroconazol and voriconazole against filamentous fungi including Aspergillus,Penicillium,Alternaria alternate,Mucor and Rhizopus species.Results The average MIC of voriconazol,amphotericin B and itroconazol against Aspergillus fumiagtus is O.29 ?g/ml,1.16 ?g/ml and 5.88 ?g/ml;the average MIC of amphotericin B and voriconazol to Aspergillus flavus is 6.39 ?g/ml and 0.22 ?g/ml;the average MIC of voriconazol,amphotericin B and itroconazol against Aspergillus niger is 0.69,2.31,and 19.75 ?g/ ml.Most of Penicillium are susceptable to amphotericin B,but 3 strains showed very high MIC to voriconazol and itroconazol.Both of the testing strains of Mucor and Rhizopus were resistant to all of the three antifungal agents.Conclusion Amphotericin B,itroconazol and voriconazole possessed different susceptibility on different types of filamentous fungi.It is important for clinical laboratories to identify the filamentous fungi to the level of genus and species to help physicians choose antifungal agents correctly.

Antibiotic resistance phenotypes and genotypes of ESBLs and AmpC ?-lactamases from Klebsiella oxytoca / 中华检验医学杂志

Objective To study antibiotic resistance phenotypes and genotypes of extended spectrum ?-lactamases (ESBLs) and AmpC ?-lactamase-producing Klebsiella oxytoca isolated from specimens of respiratory tract in children.Methods Bacterial isolates were identified by API or VITEK32. Agar dilution was used for antibiotic susceptibility test,and ESBLs and AmpC were detected by confirmatory test recommended by CLSI/NCCLS and by 3-aminophenylboronic acid (APB) disk potentiation test, respectively.Microarray was used to determine the genotypes of ESBLs and AmpC ?-lactamases.Genotypes of Klebsiella oxytoca were determined by enterobacterial repetitive intergenic consensus (ERIC)- PCR.Results ESBLs were positive in 129 out of 165 isolates (78.2%).Both ESBLs and AmpC ?- lactamases were positive in 16 out of 165 isolates (9.7%).AmpC ?-lactamase alone producer was not detected in term of phenotype and genotype.CTX-M was the most common type of ESBLs and DHA was the only type of AmpC ?-lactamase in these isolates.Most antibiotic resistant strains of Klebsiella oxytoca possessed the same genotype by ERIC-PCR.Although all strains were susceptible to carbpenem,Klebsiella oxytoca with ?-lactamases were more resistant to other antibiotic agents than those without ?- lactamases.Conclusions There is high prevalence of ESBLs production among Klebsiella oxytoca isolated from children in Urumqi.The main genotypes of ESBLs and AmpC ?-lactamases are CTX-M and DHA.