BACKGROUND: The present analysis focuses on phenotypic and genotypic characterizations of efflux-mediated erythromycin resistance in Streptococcus pneumoniae due to an increase in macrolide resistance in S. pneumoniae worldwide. METHODS: We investigated the prevalence of efflux-mediated erythromycin resistance and its relevant genetic elements from 186 specimens of S. pneumonia isolated from clinical and normal flora from Tehran, Iran. The presence of erythromycin resistance genes was tested by PCR with two sets of primers, specific for erm(B) and mef(A/E), and their genetic elements with tetM, xis, and int genes. Isolates were typed with the BOX PCR method and tested for resistance to six antibiotics. RESULTS: Antibiotic susceptibility tests revealed that 100% and 47% isolates were resistant to tetracycline and erythromycin, respectively. The erythromycin and clindamycin double-disc diffusion test for macrolide-lincosamide-streptograminB (MLSB) resistance phenotype showed 74 (84%) isolates with the constitutive MLSB phenotype and the remaining with the M phenotype. BOX PCR demonstrated the presence of 7 types in pneumococci with the M phenotype. Fourteen (16%) isolates with the M phenotype harbored mef(A/E), tetM, xis, and int genes. CONCLUSIONS: The present results suggest dissemination of polyclonal groups of S. pneumoniae with the M phenotype carrying resistance genes attributed to transposon 2009.
Anti-Bacterial Agents/*pharmacology ; Bacterial Proteins/genetics ; DNA, Bacterial/metabolism ; Drug Resistance, Multiple, Bacterial/*genetics ; Erythromycin/*pharmacology ; Genotype ; Humans ; Microbial Sensitivity Tests ; Phenotype ; Pneumococcal Infections/microbiology/pathology ; Polymerase Chain Reaction ; Streptococcus pneumoniae/*drug effects/*genetics/isolation & purification ; Tetracycline/pharmacology

BACKGROUNDDespite the prevalence of Streptococcus pneumoniae serotype 19A, the molecular characteristics of this serotype are yet to be fully elucidated. The aim of this study was therefore to determine the homology of the serotype 19A in China.

METHODSPulsed-field gel electrophoresis and multilocus sequence typing were done to these forty-nine serotype 19A isolates to investigate the relationship between the strains prevalent in Beijing and other regions.

RESULTSFrom 1997 to 2006, the percentage of serotype 19A isolates increased. The susceptibility rate to penicillin and amoxicillin decreased and the resistance rate to cefuroxime increased. ST320 was the most prevalent ST, followed by ST3546. There were six new STs identified in our study. The serotype 19A strains were classified into six different pulsed-field gel electrophoresis (PFGE) patterns. ST320, which was associated with two different PFGE patterns (A and D), accounted for 32 isolates, and ST3546, which was associated with two PFGE patterns (B and E), accounted for eight isolates.

CONCLUSIONSFrom 2003 onwards, ST320 was the most common ST and the rate of resistance to cefuroxime increased significantly. Further long-term surveys of Streptococcus pneumoniae serotype 19A are required to monitor ST prevalence and antimicrobial resistance in this important human pathogen.

Child, Preschool ; China ; Drug Resistance, Bacterial ; Electrophoresis, Gel, Pulsed-Field ; Humans ; Infant ; Infant, Newborn ; Molecular Epidemiology ; Pneumococcal Infections ; drug therapy ; microbiology ; Serotyping ; Streptococcus pneumoniae ; classification ; drug effects ; genetics ; isolation & purification ; Time Factors

BACKGROUNDErythromycin-resistant Streptococcus pneumoniae isolates that causing invasive pneumococcal diseases (IPD) in Chinese children remain uncharacterized. This study aims to identify the resistance genes associated with erythromycin resistance and to determine the genetic relationships of IPD isolates in Chinese children.

METHODSA total of 171 S. pneumoniae strains were isolated from 11 medical centers in China from 2006 to 2008. All the isolates were characterized via serotyping and antibiotic susceptibility determination. The erythromycin-resistant isolates were further characterized via ermB and mefA gene detection, multi-locus sequence typing analysis, and pulsed-field gel electrophoresis.

RESULTSA total of 164 (95.9%) isolates showed resistance to erythromycin, of which 162 strains with high high-level resistance (MIC ≥ 256 µg/ml). A total of 104 (63.4%) isolates carry the ermB gene alone, whereas 59 (36.0%) harbor both ermB and mefA genes. Of the 59 strains, 54 were of serotypes 19A and 19F and were identified as highly clonal and related to the Taiwan(19F)-14 clone.

CONCLUSIONSThe erythromycin resistance rate in IPD isolates is significantly high and is predominantly mediated by the ermB gene. Isolates that carry both ermB and mefA genes are predominantly of serotypes 19A and 19F.

Adolescent ; Anti-Bacterial Agents ; pharmacology ; Child ; Child, Preschool ; Drug Resistance, Bacterial ; Electrophoresis, Gel, Pulsed-Field ; Erythromycin ; pharmacology ; Humans ; Infant ; Multilocus Sequence Typing ; Pneumococcal Infections ; microbiology ; Serotyping ; Streptococcus pneumoniae ; classification ; drug effects ; genetics ; isolation & purification

OBJECTIVETo investigate the molecule epidemic for 7 genes interrelated penicillin, erythromycin, tetracycline, vancomycin resistance of isolated Streptococcus pneumoniae (SP) in children at Suzhou area.

METHODS(1) Thirty-one pneumococcal isolates were collected from respiratory tract secretions of children with respiratory diseases from Nov 2002 to Apr 2003 at the Children's Hospital of Suzhou University (reference strain ATCC49619). (2) Penicillin susceptibility was determined by E-test, while erythromycin, tetracycline, vancomycin were determined by K-B disk. (3) The detecting of pbp2B, ermA/B, mefA, tetM, vanA, vanB genes by PCR, Sequencing pbp2B genes, Contrasting pbp2B DNA sequences among pneumococcal isolates and SP R6 [penicillin sensitive (www.ncbi.nlm.gov/nucleotide, NC-003098)].

RESULTSOf thirty-one isolates studied, the results were shown as follows; (1) Penicillin sensibility 38.7% (n = 12), penicillin resistance 61.3% (n = 19), pbp2B mutation 64.5% (n = 20); (2) Erythromycin sensibility 9.7% (n = 3), erythromycin resistance 90.3% (n = 28), ermA/B 71% (n = 22), mefA 32.1% (n = 10), ermA/B + mefA 87.1% (n = 27); (3) Tetracycline sensibility 9.7% (n = 3), tetracycline resistance 90.3% (n = 28), tetM 90.3% (n = 28); (4) Vancomycin sensibility 100% (n = 31), vanA, vanB all 0%.

CONCLUSIONAmong pneumococcal isolates at our area, penicillin, erythromycin, tetracycline resistance were high, vancomycin was sensitive. Detecting 7 genes interrelated penicillin, erythromycin, tetracycline, vancomycin resistance expressed genotypies for antibiotic resistances in pneumococcal isolates.

Anti-Bacterial Agents ; pharmacology ; Child ; China ; epidemiology ; DNA, Bacterial ; genetics ; Drug Resistance, Multiple, Bacterial ; genetics ; Erythromycin ; pharmacology ; Female ; Humans ; Male ; Microbial Sensitivity Tests ; Molecular Epidemiology ; Penicillin Resistance ; genetics ; Pneumococcal Infections ; epidemiology ; microbiology ; Streptococcus pneumoniae ; drug effects ; genetics ; isolation & purification ; Tetracycline Resistance ; genetics ; Vancomycin ; pharmacology

OBJECTIVETo analyze the mechanisms of macrolide resistance in Streptococcus pneumoniae from children in Beijing.

METHODSThe MICs of penicillin and erythromycin were determined by the E-test methods for 200 Streptococcus pneumoniae isolates collected from 2002 to 2003 at Beijing Children's Hospital. MICs of azithrhomycin, clarithromycin, acetylspiramycin and clindamycin for 147 erythromycin-resistant isolates were detected by the agar dilution methods. For phenotyping, macrolide resistance induction tests were used in erythromycin-resistant isolates. PCR was used to determine the presence of the erythromycin-resistant genes.

RESULTSOf 200 Streptococcus pneumoniae isolates, 89.5% were resistant to erythromycin. In 147 erythromycin-resistant isolates, resistance rates were as follows: azithromycin, 100%; clarithromycin, 100%; acetylspiramycin, 95.2%; and clindamycin, 95.9%. The most common macrolide resistance phenotype was the cMIS phenotype (95.9%), 1.4% had the iMLS phenotype and 2.7% the M phenotype. Erythromycin-resistant isolates were characterized for the underlying resistance genotype, with 79.6% having the ermB genotypes, 17.7% having both ermB and mefA, 2.7% having the mefA, and none having neither ermB nor mefA genotypes.

CONCLUSIONSThe rates of carriage of macrolide-resistant Streptococcus pneumoniae by children were high in Beijing during 2002 - 2003. cMLS was the most prevalent phenotype among erythromycin-resistant Streptococcus pneumoniae isolates, and ribosomal modification (ermB gene coded) was the main resistance mechanism against macrolides in Beijing region.

Anti-Bacterial Agents ; pharmacology ; Child ; China ; Clarithromycin ; pharmacology ; Clindamycin ; pharmacology ; Drug Resistance, Multiple, Bacterial ; genetics ; Erythromycin ; pharmacology ; Genotype ; Humans ; Macrolides ; pharmacology ; Microbial Sensitivity Tests ; Penicillins ; pharmacology ; Phenotype ; Spiramycin ; analogs & derivatives ; pharmacology ; Streptococcal Infections ; genetics ; microbiology ; Streptococcus pneumoniae ; drug effects ; genetics ; isolation & purification