OBJECTIVE To investigate Mycoplasma pneumoniae load index(MPLI)usefulness in the diagnosis of Mycoplasma pneumoniae(MP) infection in children.METHODS 110 throat swabs were collected with paired sera from the department of pediatry in our hospital from March to July 2008.The former fluorescence quantitative(FQ)-PCR assay was used to analyze throat swabs,microparticle agglutination assay(MAG) and MP-IgM assay for the sera.MP-IgM positive once or twice was used as a gold standard for MP infection,on which sensitivity(SEN),specificity(SPE),positive predictive value(+PV),negative predictive value(-PV) and ROC were calculated.RESULTS According to the gold standard,the values of SEN,SPE,+PV,-PV were 73.1-100.0%for a single MP-IgM,26.9-94.0% for a single MAG,46.2-94.0% for double MAG,26.9-95.2% for FQ-PCR alone and 26.9-98.8% for MPLI,respectively.CONCLUSIONS MAG shows limit in its clinical usage for the detection of MP antibodies.MPLI can diagnose acute MP infection earlier than MP-IgM.

OBJECTIVE To study the prevalence of aac(6′)-Ⅰb with its subtypes,one kind of gene for aminoglycoside-modifying enzymes in Escherichia coli.METHODS DNA sequences were analyzed in those strains with aac(6′)-Ⅰb,compared to its family marked in NCBI.Thus,its subtypes were determined.RESULTS Four strains were classical on genotype,the other one with aac(6′)-Ⅰb-Cr,and the last one with a new subtype among the 6 strains of E.coli with aac(6′)-Ⅰb.CONCLUSIONS There exist at least 3 subtypes of aac(6′)-Ⅰb,one kind of gene for aminoglycoside-modifying enzymes in local strains of E.coli.Among those subtypes,the classical type is the main,accompanied by aac(6′)-Ⅰb-Cr and its new subtype.

OBJECTIVE To investigate drug resistance of Escherichia coli,especially the prevalence of the genes for TEM and SHV type ?-lactams in ESBLs-producing E.coli. METHODS A total of 2277 strains of E.coli collected in our hospital from Jan 2006 to Nov 2008 were analyzed for drug resistance to 21 kinds of antibiotics such as aminoglycoside,?-lactams and quinolones using VITEK-32 GNS-145 or GNS-448 card following GNI + for identification.PCR methods were used to analyze TEM and SHV type ?-lactams genes in 36 strains of E.coli with ESBLs so as to study their prevalence. RESULTS From them 1025 strains of E.coli were found positive for ESBLs,with a positive rate of 45.0%.Drug resistance rates were 83.0%,74.0%,52.0%,52.0%,29.1%,27.8%,16.5%,47.0%,31.0%,54.5%,53.0%,56.8%,10.0%,53.9%,38.5%,5.0%,4.0%,5.0% and 5.0%,respectively,for ampicillin,ampicillin/sulbactam,cefazolin,cefuroxime,aztreonam,cefepime,ceftazidime,ceftriaxone,cefotaxime,ciprofloxacin,levofloxacin,gentamicin,amikacin,tobramycin,Co-trimoxazole,nitrofurantoin,piperacillin /tazobactam,cefoperazone/sulbactam and cefoxitin.None was found resistant to imipenem or meropenem.Twenty-five and 14 strains of E.coli were found positive for TEM and SHV genes,respectively(69.4% and 38.9%). CONCLUSIONS Drug resistance of E.coli is severe.The local E.coli with ESBLs shows high positive rates of TEM and SHV genes,which play an important role in its severe drug resistance.

Objective To investigate drug resistance,especially the resistance to aminoglycoside and the prevalence of the genes for aminoglycoside-modifying enzymes in Escherichia coli producing ESBLs.Methods VITEK-32 GNI+ cards and K-B methods were used to identify E.coli and detect the resistance to 18 kinds of antibiotics such as aminoglycoside and ?-lactams respectively in E.coli isolated from our hospital from January to December,2006.PCR method was used to detect the genes for aminoglycoside-modifying enzymes such as aac(3)-Ⅰ,aac(3)-Ⅱ,aac(6')-Ⅰb,aac(6')-Ⅱ,ant(3″)-Ⅰ and ant(2″)-Ⅰ in those 17 strains producing ESBLs.Results Resistance rates were 100.0%,100.0%,41.6%,100.0%,69.5%,30.5%,98.2%,81.0%,81.0%,79.6%,79.2%,34.8%,15.4%,7.1%,7.9%,5.4% and 81.0% for ampicillin,ampicillin/sulbactam,aztreonam,cefazolin,cefepime,ceftazidime,ceftriaxone,ciprofloxacin,levofloxacin,gentamicin,tobramycin,amikacin,cifoxitin,nitrofurantoin,piperacillin/tazobactam,cefoperazone/sulbactam and co-trimoxazole respectively in E.coli producing ESBLs.No drug-resistant strain imepenem was found.Positive rate was 46.4% for ESBLs.Resistance rates were 52.9%(9/17),100.0%(17/17) and 100%(17/17) for amikacin,gentamycin and tobmycin respectively in those 17 strains producing ESBLs.The most genotype for aminoglycoside-modifying enzymes was aac(3)-Ⅱ(94.1%),the second was aac(6')-Ⅰb(35.3%).The positive rates of aac(3″)-Ⅰ and ant(2″)-Ⅰ were 11.8% and 5.9% respectively.of them,one strain was resistant to aminoglycoside on phenotype,but no genes mentioned above was detected.4strains were classical on genotype,one with aac(6')-Ⅰb-Cr,the other one with a new subtype among the 6 strains of E.coli with aac(6')-Ⅰb.Conclusions Drug resistance in E.coli is rather serious.Typically,E.coli producing ESBLs shows multi-drug resistance.Positive rate for aac(3)-Ⅱ takes the first place,followed by aac(6')-Ⅰb among the genes for aminoglycoside-modifying enzymes.Aac(3″)-Ⅰand ant(2″)-Ⅰ show both lower positive rates.Aac(3)-Ⅰ and aac(6')-Ⅱ were not found.There exist at least 3 sub-types of aac(6')-Ⅰb,one kind of gene for aminoglycoside-modifying enzymes in strains of E.coli.Among those sub-types,the classical type is the main,accompanied by aac(6')-Ⅰb-Cr and its new sub-type.