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Objective To learn the biovars,antimicmbial susceptibility in Ureaplasma species isolated from respiratory tracts of infants hospitalized in tertiary children's hospital,and to provide evidences and clinical basis for the prevention and treatment of Ureaplasma infection in infants.Methods Ureaplasma species cultivation,identification and antibiotic susceptibility testing were performed using Mycoplasma IST2.The primers according to the conservative MB-Ag gene were designed to identify Ureaplasma biovars.Erythmmcin resistant genes (ermA,ermB and ermC) and active effiux transporter genes (mefA/E,msrA/B and mreA) were amplified using PCRs.Results A total of 78 Ureaplasma positive cases,of them,48 Ureaplasma strains were isolated from premature neonates.Biovar 1 was present in 51 (65.38％) strains,and biovar 2 was present in 27 (34.62％) strains.There were no significant differences among sex,premature infant,age,gestational age,birth weight,length of stay (P ＞ 0.05).The drug resistance rates to ciprofloxacin and ofloxacin were 80.77％,and to tetracycline was 1.28％.All strains were sensitive to doxycycline,josamycin and pristinomycin.The drug resistance rates to the macrolide antibiotics (erythromycin,azithromycinand and clarithromycin) were ＜ 12％.There was no statistically significant difference among the drug resistance rates of different biovars and these antibiotics (P ＞ 0.05).Only the methylated enzyme gene (ermB) and the active efilux pump gene (msrA/B) were detected,and the detection rate was 39.74％ and 12.82％ respectively.The ermB gene mainly exists in biovar 2,and the detection rate is 55.56％ (P ＜ 0.05).The msrA/B was balanced distributed between biovar 1 and 2 (P ＞ 0.05).A total of 78 Ureaplasma strains were isolated from 24 cases of neonatal septicemia,30 cases of congenital infection pneumonia,9 cases of retinopathy of prematurity,9 cases of neonatal intracranial hemorrhage,and 15 cases of bronchopulmonmT dysplasia.Conclusion Biovar 1 is more prevalent in Ureaplasma species isolated from infant respiratory tract,and higher detection rate of Ureaplasma is found in the preterm infants.All Ureaplasma strains have high drug resistance to both ciprofloxacin and ofloxacin,but low drug resistance to the macrolide antibiotics (erythromycin,azithromycin and clarithromyc),that could be used as a first choice for the treatment of Ureaplasma infection.Erythromycin resistance gene ermB,mainly exists in biovar 2.
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In order to understand the resistance against common antibiotics in clinic and macrolide antibiotic-resistant mechanism of Streptococcus pneumoniae (S.pneumoniae) isolates in Zhejiang area,both K-B slip method and E-test were applied to determine the sensitivity of 138 S.pneumoniae isolates to nine antibiotics,and the ermB and mefE genes in those isolates which associated with macrolide antibiotics-resistance closely were detected by PCR.Subsequently,correlation among ermB and mefE genes and the erythromycin resistance were analyzed.For these 138 S.pneumoniae isolates,93.5% (129/138) of the strains were resistant to erythromycin,but only 2.9%～4.3% strains were resistant to cefotaxim,cefuroxime,amoxicillin and levofloxacin.The positive rate of ermB gene in the isolates (91.3%,126/138) was significantly higher than that of mefE gene (33.3%,46/138) (P<0.05).Both of these two genes existed in 27.5 % (38/138) of the strains and all of the strains without ermB and mefE genes were sensitive to erythromycin.The erythromycin resistance rate (62.5%) of mefE gene positive strains was remarkably lower than that of the mefE&ermB gene positive strains (100%) and the ermB gene positive strains (97.7%) (P<0.05).All the data mentioned above demonstrated that erythromycin is not an appropriate antibiotic to treat the infectious diseases caused by S.pneumoniae.Moreover,ermB is the predominant erythromycin resistance gene in S.pneumoniae isolates and ermB gene could inspire stronger erythromycin resistance than mefE gene.
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Objective To study the relationship between erythromyein sensitivity and ermB gene in 143 Ureaplasma urealyticum (Uu) clinical isolates. Methods We detected the minimum inhabit concen-trations (MICs) of Uu to erythromycin by broth dilution method and MIC≥8 μg/ml was used as standard concentration of resistance to erythromycin. Polymerase chain reaction was used to detect the ermB gene and biotype Uu with primers based on multi-band antigen gene. Results The MICs, MIC50 MIC90 of Uu to erythromycin were ≤0. 125 μg/ml to ≥128 μg/ml, 16 μg/ml, and ≥128 μg/ml, respectively, with a high resistance rate of 64.38%. ermB gene, which was mainly detected in Uu with MIC≥8 μg/ml, was positively detected in 40 out of 143 Uu strains (27.97%). No significant differences of the resistance to erythromycin and positive rate of ermB gene were found between the two biovars in the study . Conclusion ermB gene may probably be one of the important genes conferring resistance to erythromycin in Uu. Further studies are needed to discover the difference of resistance and mechanism of erythromycin between the two bi-ovars.