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Objective To study on the drug-resistance mechanism of Brucella resistance to Quinolone antibiotics to guide the selection and use of antimicrobial agents in clinical practice. Methods Six strains of Brucella melitensis(Bru1, Bru2, Bru3, Bru4, Bru5, Bru6) were selected to be induced resistance to levofloxacin in vitro respectively. The MICs of the 6 strains of Brucella melitensis and induced resistant strains were measured by agar dilution method. The sensitivity to Quinolone antibiotics (Levofloxacin, Ciprofloxacin, Lomefloxacin, Norfloxacin, Fleroxacin, Ofloxaein) of 6 strains of Brucella melitensis and induced resistant strains was measured by K-B method. The gyrA of the 6 strains of Brucella melitensis and induced resistant strains was amplified by PCR, then the nucleotide sequence of the genes were analyzed. Results The MICs of Bru1,Bru2,Bru3,Bru4, Bru6 were 0.50 μg/ml and Bru5 was 0.25 μg/ml. The strains Bin3, Bru4 were induced into drug-resistant strains by Levofloxacin, then were named LEVR3 and LEVR4 respectively. The MICs of LEVR3 and LEVR4 were 64,128 μg/ml with 128 and 256 times higher than that of the parental strains. The 6 strains of Brucella melitensis were sensitive to Quinolone antibiotics, LEVR3 and LEVR4 were resistant to Quinolone antibiotics. Neucleotide sequence analysis and comparison of the derived amino acid sequence revealed that Quinolone resistance-determing region of GyrA had a substitution at position Ala87 and Asp91 in laboratory resistant strains. Conclusion The results of in vitro experiments show that acquired resistance of Brucella melitensis strains to Levofloxacin could beinduced when exposed to high level of some antibacterial agents for short term. Two drug-resistant strains occur mutations in gyrA and have cross-resistance to other Quinolones.

6.Correlations between fasting plasma glucose level in the first trimester and gestational diabetes mellitus

Li YANG ; Ling FAN

Chinese Journal of Perinatal Medicine 2014;17(2):88-92

Objective To investigate the relationships between fasting plasma glucose (FPG) level in early pregnancy and gestational diabetes mellitus (GDM).Methods Data of 11 477 pregnant women who accepted prenatal care in Beijing Obstetrics and Gynecology Hospital from October 2011 to September 2012 were collected.FPG was tested during 8 to 12 weeks of pregnancy in all women and those with FPG＜7.00 mmol/L were recruited.Women accepted 75 g oral glucose tolerance test (OGTT) during 24 to 28 weeks of pregnancy.The GDM diagnostic criteria was with reference to the criteria of International Association of Diabetes and Pregnancy Study Group.Mann-Whitney U test was used to analyze the difference of early pregnancy FPG between normal pregnant women and GDM women.Receiver operating characteristic (ROC) curve was used to analyze the validity and applicability of using early pregnancy FPG in GDM diagnosis.Chi-square test was used to analyze the relationship between the FPG levels and GDM diagnosis.Results There were 1 535 (13.4％) women diagnosed as GDM in 24 to 28 weeks of pregnancy (the rest 9 942 normal cases were taken as the controls).The median FPG level of the GDM group was 4.89 mmol/L (4.62-5.15 mmol/L),which was higher than that of the controls [4.75 mmol/L(4.53-4.98 mmol/L)] (Z=-13.994,P=0.000).The maximum area under curve (AUC),which was used to predict GDM with early pregnancy FPG,was 0.599 (95％ CI:0.582-0.617).Taking FPG 4.88 mmol/L as the cutoff value,the sensitivity was 0.523 and the specificity was 0.645.While taking FPG 5.10 and 5.60 mmol/L as the cutoff value,the sensitivity was 0.334 and 0.068,and the specificity was 0.811 and 0.983,respectively.When the FPG level ≤ 4.09,-4.60,-5.10,-5.60,-6.10 and ≥ 6.10 mmol/L,the GDM diagnostic rate gradually increased [8.5％(23/212),9.9％(335/3 379),12.3％(719/5 858),20.7％(359/1 734),40.2％ (78/194) and 52.5％ (21/40)] (x2=300.523,P=0.000).GDM diagnostic rate in FPG ≤ 4.09,-4.60,-5.10 and-5.60 mmol/L group were lower than that in FPG ≥ 5.60 but ＜6.10 mmol/L group and ≥ 6.10 mmol/L group (x2 were 67.242,164.680,128.125,37.860,55.843,76.856,58.589 and 23.484,all P=0.000) ; GDM diagnostic rate in FPG ≤ 4.09,-4.60,-5.10 mmol/L group were lower than that in FPG ≥ 5.10 but ＜5.60 mmol/L group (x2 were 22.877,113.717 and 78.040,all P=0.000); GDM diagnostic rate in FPG ≥ 4.09 but ＜4.60 mmol/L group was lower than that in FPG ≥ 4.60 but ＜5.10 mmol/L group (x2=11.803,P=0.001).When using abnormal fasting and postprandial OGTT level as GDM diagnostic criteria,the ratio of GDM in early pregnancy FPG level ≥ 5.60 but ＜6.10 mmol/L group and FPG ≥ 6.10 mmol/L group were higher than that of the FPG level ＜5.60 mmol/L group [50.0％ (39/78) and 71.4％ (15/21) vs24.1％ (346/1 436),x2 were 12.456 and 21.443,all P＜0.003].Conclusions Early pregnancy FPG level is not proper to be used as an early diagnostic tool of GDM.However,when early pregnancy FPG level is equal to or greater than 5.60 mmol/L,the incidence of GDM in late pregnancy will increase significantly.