Molecular epidemiology of carbapenem resistant Klebsiella pneumoniae in a hospital in Beijing / 中华预防医学杂志

Objective@#To reveal the molecular epidemiological characteristics of Carbapenem-Resistant Klebsiella pneumoniae (CRKP) isolated from a three level teaching hospital in Beijing.@*Methods@#Pulsed field gel electrophoresis (PFGE) was carried out to subtyping 375 CRKP isolated in that hospital between May 2010 and October 2015. Fifteen strains were chose based on the PFGE patterns to be analyzed by multi-locus sequence typing (MLST) and detection of carbapenem-resistance genes. One strain (A1502) was selected for whole genome sequencing and analyzing.@*Results@#The 375 CRKP were divided into 140 PFGE types, among which five types contained more than five strains. The dominant types were distributed in different time periods and wards. Among the 15 strains tested by MLST and carbapenem-resistance genes detection, 13 were ST11 strains carrying KPC-2 gene. By genome-based typing, A1502 was clustered together with strains from other hospitals of Beijing but far from the strains from Shanghai and Hangzhou.@*Conclusion@#The CRKP epidemic clone (ST11 clone carrying KPC-2) has been spreading within single hospital and across different hospitals in Beijing.

Research on the mutant prevention concentration of tigecycline for Klebsiella pneumoniae / 中国感染与化疗杂志

Objective To investigate the potential tigecycline resistance of Klebsiella pneumoniae during treatment.Methods The minimum inhibitory concentrations (MICs) and the mutant prevention concentrations (MPCs) of tigecycline were determined for K.pneumoniae isolates with four different resistant profiles.Corr.elations between MICs and MPCs were analyzed.We combined with the pharmacokinetic parameters of tigecycline to estimate the potential of emerging resistance to tigecycline monotherapy in K.pneumoniae.Results The MPCs of tigecycline for the carbapenem-and fluoroquinolone-resistant isolates were found to be 8-fold higher than those for carbapenem-and quinolones-susceptible isolates.Our data showed that the MPCs range and MPC90 values of tigecycline were 4-512 mg/L and 64 mg/L,respectively,which were much higher than the therapeutic concentrations of tigecycline in serum and tissues.Conclusions Long-term tigecycline monotherapy may predispose the emergence of resistance in K.pneumoniae,which is not recommended.It is desirable to carry out ongoing monitoring of K.pneumoniae susceptibility and tigecycline treatment effect.

Isolation and identification of Malassezia furfur from lower respiratory tract secretions / 中华检验医学杂志

Objectives To culture and isolate Malassezia furfur which were suspected in sputum smears,and then to identify the isolates systematically.Methods From March 2010 to September 2011,133 lower respiratory tract secretion samples were collected in Beijing Hospital of the Ministry of Health which were suspected containing Malassezia furfur by Parker ink staining.The samples were inoculated and cultured on CHROMagar mediums containing 1％ Tween 60 ( which was modified from Candida chromogenic media) in the atmospheric environment at 35 ℃.The suspected colonies were selected and cultured on both SDA plates containing 0.5％ Tween 40 and SDA plates containing 0.5％ Tween 60.The traditional phenotypic identification methods were used to identify the pure colonies,including staining,growth on Sabouraud agar plates,Tween test,decomposing Escalin,Catalase test,Tween precipitation test and castor oil test.Then the suspected colonies were identified by analyzing the sequences of 18s rRNAs.Results The isolation rate of Malasseziafurfur from lower respiratory tract secretions was 47.4％ (63/133) and 63 strains were also identified as Malassezia furfur by traditional phenotypic identification methods combined with the 18s rRNA gene sequence analysis.Malassezia can be significantly distinguished from Candida by direct smear of the specimen with Parker ink staining.Conclusions Malassezia furfur was found as pink colonies on modified Candida chromogenic media which were significantly different from other Candida colonies.The isolation rate of lower respiratory tract secretions can be improved by modified Candida chromogenic media.The identification accuracy can be further improved by combining traditional phenotypic identification methods with 18s rRNA sequence analysis.

Antibiotic resistance of clinical isolated bacteria in elderly inpatients in recent 3 years / 中华老年医学杂志

Objective To analyze the antibiotic resistance of clinical isolated bacteria in elderly inpatients in Beijing Hospital from 2006 to 2008.Methods A total of 5710 strains isolated from elderly inpatients received antibiotic sensitivity test (AST) by using K-B method, and the data were analyzed with WHONET 5.4 software.Results During the 3 years, in constituent ratio of bacteria, P.aeruginosa, E.coli and Stenotrophomonas maltophilia were at the top of gram-negative bacteria.And S.aureus, coagulase-negative Staphylococcus (CONS), S.pneumoniae and Enterococcus spp.were at the top of gram-positive bacteria.The results of AST in vitro showed that 19 of 121 strains of S.pneumoniae were penicillin-insensitive S.pneumoniae (PNSP).In 690 strains of S.aureus, the methicillin-resistant S.aureus (MRSA) ratio was 80.2%, and vancomycin-insensitive strains were not found.And 114 strains of Enterococeus faecalis and 95 strains of Enterococcus faecalis were isolated, while the antibiotic resistance of the latter was stronger than the former, and 19 strains were vancomycin-resistant strains.The detection ratios of E.colt producing ESBLs were 41.7%, 55.0% and 56.8%, and the detection ratios of Klebiella pneumonia producing ESBLs were 16.0%, 22.4% and 27.3 %.The antibiotic resistance of ESBL-producing bacteria was much stronger than non-ESBLs producing bacteria.Multi-antibiotic resistant strains of Pseudomonas aeruginosa and Acinetobacter spp.were found.Conclusions It is necessary to detect the drug-resistant strains periodically for understanding the changes in bacterial resistance and providing a theoretical basis for the medication by the clinical experience.

The molecular characteristics and genetic background of VanB phenotype-van A genotype vancomycin resistant Enterococcus / 中华检验医学杂志

Objective To investigate the structure of Tn1546 like elements,the molecular features and genetic background of VanB phenotype-vanA genotype VREs and to explain the difference between phenotype and genotype. Methods Twenty-one VREs were collected in Beijing Hospital from March 2008 to January 2009. Etest was used to determin MICs of ten antibiotics. PCR product sequencing, PFGE and MLST were performed to study the molecular features and genetic background of the 21 VREs. Results All VREs were vanA genotype, but 3 of them( 14. 3% ) exhibited the VanB phenotype. Based on PFGE analysis, 21 VREs belonged to 9 different patterns. Six STs were identified by MLST analysis. The analysis of the structure of Tn1546 like elements showed the deletion of vanY, vanZ and the insertion of ISEfa4 in orf2-vanR intergenic region may be related to the formation of VanB phenotype-wanA genotype. Conclutions VanB phenotype-vanA genotype VREs were rarely found in China. The results of vanA cluster rearrangements could partly explain the causes of difference between phenotype and genotype.

Mutant Prevention Concentration of Three Cephalosporins Against Staphylococcus aureus and Streptococcus pneumoniae / 中华医院感染学杂志

OBJECTIVE To determine the mutant prevention concentration(MPC) of 3 cephalosporins against clinical isolates of Staphylococcus aureus and Streptococcus pneumoniae.METHODS Agar dilution was used to determine the minimum inhibitory concentration(MICs) and MPCs of cefaclor,cefprozil and cefuroxime against S.aureus and the MICs to Str.pneumoniae.The MPCs against Str.pneumoniae were determined by mixing-bacterium.RESULTS The MPCs and the ratio of MPC90/MIC90 of cefaclor,cefprozil and cefuroxime against S.aureus were 32,16;16,16;2,8;and the MPCs and the ratio of MPC90/MIC90 against Str.pneumoniae were 8,16;4,32;2,8,respectively.CONCLUSIONS The ability of cefuroxime for restricting the selection of resistant mutant of Str.aureus and S.pneumoniae is stronger than cefaclor and cefprozil.

Distribution and Drug Resisance of Pathogens Isolated from Ventilator-associated Pneumonia Patients in ICU / 中华医院感染学杂志

OBJECTIVE To know the distribution and drug resistance of the ventilator-associated pneumonia(VAP) bacteria in the intensive care unit(ICU),and to provide a reasonable basis for the clinical use of antibiotics. METHODS We used the Tiek Biagnostic systems to identifly microorganisms and antibiotic susceptibility.The result of the drug sensitivity test was analyzed with SPSS13.0. RESULTS A total of 538 strains were isolated from the sputum samples of the ventilator-associated pneumonia patients in the ICU over the last 4 years,in which Gram-negative bacteria were 361(the isolation rate 69.3%).Pseudomonas aeruginosa was the most common.Gram-positive bacteria were 143(the isolation rate 26.6%),in which Staphylococcus aureus was the most common.Twenty-two strain were fungi(the isolation rate 4.1%).Most of the pathogenic bacteria maintained high sensitivity rate to imipenem,vancomycin and quinupristin/daefopristin;but the drug resistance rate to other antibiotics was high and on the rise year by year. CONCLUSIONS The pathogens types of VAP was,complex,and multi-drug resistant.We should emphasize the reasonable application of the antibiotics and strengthen the monitoring of drug resistantce,and rational use of antibiotics to improve the cure rate.

Fungus Isolation from Clinically Used Abacterial Body Fluid:Flora Distribution and Drug Resistance / 中华医院感染学杂志

OBJECTIVE To study fungal isolation and its drug resistance from abacterial body fluid.METHODS The abacterial body fluid for patients in our hospital was cultured by BacT Alert 120 and routine method.The strains which had been isolated were identified by development culture method and VITEK-YBC card or API-20C AUS reagent stripes.Furthermore,drug sensitive test was done by ATB FUNGUS2 drug sensitive reagent kit.RESULTS From the 898 samples with positive cultures of abacterial body fluid.8 species and 79 strains were isolated.Among the 79 fungal strains(8.8%),Candida albicans was 40 strains(50.6%),C.tropicalis was 12 strains(15.2%),C.glabrata was 11 strains(13.9%),C.parapsilosis was 9 strains(11.3%),C.guilliermondii was 4 strains(5.1%),C.krusei was 1 strain(1.3%),Cryptococcus were 1 strain(1.3%),and Mucor were 1 strain(1.3%).From them,13 strains(16.5%) were isolated in ICU,10 strains(12.7%) were in neurosurgical department,9 strains(11.4%) in oncological department,8 strains(10.1%) in urological surgery department,7 strains(8.9%) in thoracic surgery department,7 strains(8.9%) in pneumology department,6 strains(7.6%) in hematology department,5 strains(6.3%) in gerontology department,4 strains(5.1%) in orthopedic department,4 strains(5.1%) in endocrinology department,2 strains(2.5%) in nephrology department,and 4 strains(5.1%) in other units.The antifungal activity of amphotericin B,nystatin and flucytosine for fungus was quite perfect with sensitive ratio of 90%.But the drug resistance ratio to miconazole,ketoconazole and econazole was upward on 20-30%.CONCLUSIONS It′s important and necessary to monitor the circumstance of fungal infection and resistance of the pathogenic fungi due to its increased morbidity.

An investigation of factors influencing three dimensional test for be ta-lactamases / 中华检验医学杂志

10 mm, inhibitor concentration

Identification of Streptococcus pneumoniae resistant to optochin / 中华检验医学杂志

Objective Correctly identify Streptococcus pneumoniae resistant to optochin and other alpha hemolytic streptococcus susceptible to optochin.Methods Optochin susceptibility test, bile resolution test, latex agglutination test as well as some biochemical methods (VITEKCC4-GPI identifying cards,API-Strept identifying bar, VITEK TWO-GPC identifying cards) were applied.Results It was observed that 2 strains(0.3%)of Streptococcus pneumoniae out of 630 were resistant to optochin and 31strains of Streptococci, classfied as alpha hemolytic streptococci, susceptible to optochin, including 13 of S. mitis, 6 of S.oralis, 6 of S. twin, 3 of S. acidominimus, 2 of S.intermedius and 1 of S. constellatus. The inhibition zone of these alpha hemolytic streptococci susceptible sensitive to optochin was within the range of 14-17mm in diameter, in not 20 mm or more than 20 mm, compared with the inhibition zone of most strains of S.pneumoniae. Most of these alpha hemolytic streptococci (93.5%) susceptible to optochin showed highly resistance to benzoxazolecillin,to which most Streptococci (94%) showed sensitivity . Conclusion S.pneumoniae can be effectively identified by bile resolution test and latex agglutination test because of its high specificity with credible test results. API-Strept identifying bar and VITEK TWO-GPC identifying cards can be applied to identify S. pneumoniae resistant to optochin.

Integron-mediated multidrug resistance in clinical multi-reisistant Pseudomonas aeruginosa / 中华检验医学杂志

Objective To investigate the action of integron-mediated multidrug resistance in clinical multi-resistant Pseudomonas aeruginosa.Methods The strains of multi-resistant Pseudomonas aeruginosa were selected with K-B susceptibility method. The three-dimensional method was taken to differentiate the various beta-lactamases. The integron was determined by PCR with integron-specific primer. DNA sequencing was also used to analyze resistance-related gene in the integron in multi-resistant Pseudomonas aeruginosa.Results The positive rate of integron detection in multi-resistant Pseudomonas aeruginosa was 42.4%.Three kinds of different length integron were found .They were 750bp,1 000bp and 2 500bp and aadB,aadA2,aadB,aac6-II and PSE-1 were the resistance-related gene cassette in the integrons.Conclusions Integron took part in mutiple resistance in multi-resistant Pseudomonas aeruginosa.We should pay more attention to integron-mediated horizontal transference of mulidurg resistance to lessen the occurrence of multi-resistant strains.

Study on nongonococcal genitourinary tract infections and drug resistance of Mycoplasma to antibiotics / 中华检验医学杂志

Objective To compare the isolation rate of Ureaplasma urealyticum(Uu), Mycoplasma hominis(Mh) and Chlamydia trachomatis(CT), and to analyze the resistance of Mh and Uu to 6 kinds of antibiotics. Methods CT in genitourinary tract of 1 059 NGU patients was detected by kit of VIDAS. Uu and Mh in genitourinary tract was detected by kit of IST. Results From 1 059 tested samples, the total positive percentage for Mycoplasma and Chlamydia was 36.3% and 5.6% respectively, 14.8% and 3.7% for Mycoplasma and Chlamydia from male samples, 52.6% and 7.2% for Mycoplasma and Chlamydia from female samples. The colony counting result showed that the number of female samples with colonies more than 104 cfu/ml was greater than that of male samples, 73.2% versus 60.3% for Uu and 30.5% versus 25% for Mh. The sensitivity of Mycoplasma to antimicrobial agents was as follows from high to low: Pristinamycine, Doxycycline, Josamycin, Tetracycline, Ofloxacin, Erythromycin. Conclusions The isolation of Mycoplasma was more than that of Chlamydia from patients with genitourinary tract infection.Resistance monitoring of Mycoplasma periodically played an important role in clinical drug treatment.

In vitro Antibacterial Activity of Home-made Rifamycin against Meticillin Resistant Staphylococcus and Other Pathogens of Clinical Isolates / 中华医院感染学杂志

OBJECTIVE The in vitro activity of home-made rifamycin was investigated.METHODS Minimal inhibitory concentrations(MICs) were determined by agar dilution method using multipoint inoculator.RESULTS The results indicated that MIC50 and MIC90 of rifamycin against MRSA and MSSA were similar to vancomycin. The values were 1 and 2 mg／L, respectively. Rifamycin against MRSE was 4 times stronger than vancomycin.The value of MIC50 was 0.5 mg／L.The MIC50 of rifamycin against S.pneumoniae,Branhamella catarrhalis,and Listeria monocytogenes were 8,128 and 4 times lower than vancomycin, respectively.CONCLUSIONS There are good antibacterial activity of home-made rifamycin against meticillin resistant Staphyloccocus and the most species of clinical isolates,so can be used the infective diseases by MRSA and MRSE.

A novel method for rapid identification and drug resistance of Moraxella catarrhalis / 中华检验医学杂志

Objective To establish a novel method for rapid identification and drug resistance of Moraxella catarrhalis, Different sourses of blood and the formula of chocklate agars were detected the Growth Index(GI). Methods Moraxella catarrhalis from specimens contaminated by microbial flora were isolated with a choclate agar with 50 mg/L vancomycin (CHOC-V) method. Nine media were inoculated,on which GI were calculated and compared. beta-Lactamase were determined by nitrocefin slip method. Results 228 strains of Moraxella catarrhalis and 203 strains of recent limbus bacteria were examined. The sensitivity of this method was 100%,and the specificity was 100%. The GI of Moraxella catarrhalis on chocklate agars and blood agars was higher than that of the BCA, NUA, MHA ( P

Distribution of anaerobes infection in gingivitis and comparative in vitro activity of ?-lactamase / 中华检验医学杂志

Objective To understand the distribution of anaerobes in gingivitis infection, and anaerobes sensitivity to ? lastams Methods 44 specimens were taken from the gingival crevicular fluid of gingivitis. The anaerobic bacteria were cultured and identified Minimal inhibitory concentrations (MIC) were measured by using agar dilution method Results Among all samples, the isolation of anaerobes was 100%, the isolation of P.melaninogenica was 86.4%, P.intermedia was 56.8%, B.forsythus was 52.3%, P.gingivalis was 65.9%, F.mucleatum was 63.6%, P.micros was 52.3%, Actinomyces ssp was 38.6% and Capnocytophaga ssp was 9.1% respectively. The anaerobes are sensitive to ? lastams. Conclusion In gingival crevicular fluid, the infection rates of P.melaninogenica, P.intermedia, B.forsythus, P.gingivalis, F.mucleatum, P.micros, and Actinomyces ssp were significantly higher than those of the other anaerobes. ? lastams can be used for the treatment of anaerobes infected gingivitis.

Evaluation and applicatipn of media for isolation of haemophilus / 中华检验医学杂志

Objective　To select suitable media for increasing isolation rate of haemophilus.Methods　Haemophilus was inoculated on seven types of media.The average growth index(GI) of Haemophilus was calculated and Haemophilus was isolated from 325 specimens of the respiratory tract and its isolation rate was compared with that media of brchoc and brchoc-V agare.Results　The GI of media with 2% fresh yeast infusion and 50% of meat infusion was higher than that of those with no yeast and meat infusion.The GI of Haemophilus on BRchoc was higher than that of the BSchoc(P<0.001).The isolation rate of Haemophilus from 325 respiratory tract specimens on BRchoc-V was 77.2%,which was significantly higher than that on the medium BRchoc (32.0%).Conclusions　BRchoc-V is a better medium for isolation of Haemophilus.This medium is effective to improve the isolation rate of Haemophilus.