Genomic Insights of First ermB-Positive ST338-SCCmecVT/CC59 Taiwan Clone of Community-Associated Methicillin-Resistant Staphylococcus aureus in Poland.

We report the first Polish representative of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA), lukS/F-PV-positive, encoding the ermB gene, as a genetic determinant of constitutive resistance to macrolides, lincosamides, and streptogramin B antibiotics, cMLS-B. This is the first detection of the CA-MRSA strain responsible for nosocomial infection in the Warsaw Clinical Hospital. Resistance to ß-lactams associates with a composite genetic element, SCCmec cassette type VT (5C2&5). We assigned the strain to sequence type ST338 (single-locus variant of ST59), clonal complex CC59, spa-type t437, and agr-type I. Genomic-based comparison was designated SO574/12 as an international Taiwan clone, which has been so far described mainly in the Asia-Pacific region. The ermB gene locates on the chromosome within the 14,690 bp mobile element structure, i.e., the MESPM1-like structure, which also encodes aminoglycoside- and streptothricin-resistance genes. The MESPM1-like structure is a composite transposon containing Tn551, flanked by direct repeats of IS1216V insertion sequences, which probably originates from Enterococcus. The ermB is preceded by the 273 bp regulatory region that contains the regulatory 84 bp ermBL ORF, encoding the 27 amino acid leader peptides. The latest research suggests that a new leader peptide, ermBL2, also exists in the ermB regulatory region. Therefore, the detailed function of ermBL2 requires further investigations.

An analysis on biovars and antimicrobial susceptibility of 78 Ureaplasma strains isolated from respiratory tract of hospitalized infants / 预防医学

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.

Resistance detection and macrolide antibiotic-resistant mechanism of Streptococcus pneumoniae isolates / 中国人兽共患病学报

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.

Study on the relationship between erythromycin sensitivity and ermB gene in Ureaplasma urealyticum / 中华微生物学和免疫学杂志

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.