Fenotipos y mecanismos de resistencia a macrólidos y lincosamidas en aislados de Streptococcus agalactiae con significación clínica en un período de ocho años (2002-2010) / Phenotypes and mechanisms of resistance to macrolides and lincosamides in Streptococcus agalactiae isolates with clinical significance in an eight-year period (2002-2010)

Introducción. Streptococcus agalactiae es el agente etiológico más prevalente de enfermedad invasiva en el recién nacido (sepsis, neumonía y meningitis), además de tener un papel importante en fiebres puerperales, infecciones del tracto urinario e infecciones postquirúrgicas. El objetivo de nuestro trabajo fue conocer la evolución de la resistencia a macrólidos y lincosamidas. Métodos. El fenotipo de resistencia se estableció mediante aproximación de discos (eritromicina-clindamicina): M (bomba de expulsión) o MLSB (metilasa). Los mecanismos genéticos de resistencia se establecieron mediante PCR para los genes ermB, ermA, ermTR, mefA/E. El tipado molecular se realizó por macrorrestricción de ADN cromosómico y electroforesis en campo pulsado. Resultados. Durante 8 años se aislaron 300 cepas de S. agalactiae, de las que 78 (26%) cepas fueron resistentes a eritromicina y 70 (23%) cepas fueron resistentes a lincosamidas. El 21% presentaron fenotipo MLSB constitutivo (todas portadoras del gen ermB, excepto una) y CMI90 para eritromicina ≥ 256 mg/L. El 2.3% presentaron fenotipo MLSB inducible (todas portadoras del gen ermTR) con CMI90 = 6 mg/L y el 2,7% fenotipo M (todas portadoras de los genes mefA/E) con CMI90 = 6 mg/L. El estudio de identidad clonal reveló dos clones predominantes que incluían el 56,6% de las cepas estudiadas. El 90,5% de las cepas del clon A portaban el gen ermB. Conclusiones. El estado de resistencia en nuestra área geográfica se encuentra en el límite superior del detectado en el resto del país, pero no se ha observado incremento a lo largo del periodo estudiado(AU)

Introduction. Streptococcus agalactiae is the most prevalent agent of invasive disease in the newborn (sepsis, pneumonia, and meningitis), as well as an important cause of puerperal fever, urinary tract infection and surgical site infection. The aim of our study was to know the evolution of macrolide and lincosamide resistance in this microorganism. Methods. Resistance phenotypes were established according to the erythromycin-clindamycin induction test: M (efflux pump) or MLSB (methylase). Genetic mechanisms were detected by PCR for the following genes: ermB, ermA, ermTR, and mefA/E. Molecular typing was based on chromosomal DNA macrorestriction and detection of fragments using pulsed-field gel electrophoresis. Results. During 8 years, 300 isolates of S. agalactiae were recovered. Seventy-eight (26%) were resistant to macrolides, and seventy (23%) were resistant to lincosamides. Constitutive MLSB was observed in 21% of the isolates (all but one carrying the ermB gene), with a erythromycin MIC90 ≥ 256 mg/L. Inducible MLSB was observed in 2.3% of the isolates (all carrying the ermTR gene), with a MIC90 of 6 mg/L. M phenotype was observed in 2.7% of the isolates (all carrying the mefA/E gene), with a MIC90 of 6 mg/L. Molecular typing revealed the presence of two major clones (A and B) comprising 56.6% of the isolates. Most of the isolates (90.5%) belonging to clon A carried the ermB gene. Conclusions. Macrolide resistance in our area is similar to that observed in the rest of Spain, but there has been no increase in the incidence rate along the study period(AU)

[Macrolide-resistant Streptococcus pneumoniae on the islands of Gran Canaria and Lanzarote (Spain): molecular mechanisms and serogroup relationships]. / Resistencia antibiótica a los macrólidos en Streptococcus pneumoniae en las islas de Gran Canaria y Lanzarote: mecanismos moleculares y relación con serogrupos.

BACKGROUND: Macrolide resistance in Streptococcus pneumoniae is coded by the ermB and mefA/E genes. The aim of this study was to determine the status of macrolide-resistance, the molecular mechanisms involved, the serogroup relationships, and the level of co-resistance in S. pneumoniae isolates from Gran Canaria and Lanzarote, in the Canary Islands, Spain. METHODS: Macrolide resistance phenotypes were investigated in 261 S. pneumoniae clinical isolates over a two-year period (2004 and 2005). Genotypes were determined by PCR (detection of ermB and mefA/E genes). RESULTS: Overall macrolide resistance was 40.6% (106 isolates); 79.2% (84) of resistant isolates presented the MLSB phenotype (98.8% harbored the ermB gene), with a predominance of serogroup 19, and 20.8% (22) presented the M phenotype (77.3% displayed the mefA/E gene), all associated with serogroup 14. Worthy of note, the M phenotype was found in 8 invasive isolates from Lanzarote (80%) all from serogroup 14. The ermB and mefA/E genes were detected in 7 isolates belonging to serogroup 19. Absence of co-resistance was observed most frequently in serogroup 14 (66.7%). Co-resistance with penicillin G, tetracycline, and trimethoprim-sulfamethoxazole was associated with serogroup 19 (36.8%). Two isolates (0.8%) were resistant to telithromycin. CONCLUSION: The frequency of macrolide resistance mechanisms in the Canary Islands is different from that observed in the rest of Spain, particularly in Lanzarote, where 80% of isolates harbored the mefA/E gene and belonged to serogroup 14.

Resistencia antibiótica a los macrólidos en Streptococcus pneumoniae en las islas de Gran Canaria y Lanzarote: mecanismos moleculares y relación con serogrupos / Macrolide-resistant Streptococcus pneumoniae on the islands of Gran Canaria and Lanzarote (Spain): Molecular mechanisms and serogroup relationships

Introducción. La resistencia a macrólidos en Streptococcus pneumoniae está codificada por los genes ermB y mefA/E. Nuestro objetivo fue conocer el estado de resistencia a macrólidos, los mecanismos moleculares implicados, la relación con los serogrupos y la corresistencia en las islas de Gran Canaria y Lanzarote. Métodos. Sobre 261 cepas aisladas durante dos años (2004-2005), se estudiaron los fenotipos de resistencia a macrólidos. Los genes ermB y mefA/E se detectaron por reacción en cadena de la polimerasa (PCR). Resultados. La resistencia global a macrólidos fue del 40,6% (106 cepas). El 79,2% (84) de las cepas presentó el fenotipo MLSB (el 98,8% portó el gen ermB), con predominio del serogrupo 19. El 20,8% (22) de las cepas presentó el fenotipo M (el 77,3% portó el gen mefA/E), con predominio del serogrupo 14. Destacamos la presencia del fenotipo M (8 cepas, 80%) en cepas invasivas de Lanzarote, todas del serogrupo 14. Se detectaron 7 cepas del serogrupo 19 portadoras de los genes ermB y mefA/E. La ausencia de corresistencia se relacionó con el serogrupo 14 (66,7%). La corresistencia con penicilina G, tetraciclina y trimetoprim-sulfametoxazol se relacionó con el serogrupo 19 (36,8%). Dos cepas (0,8%) fueron resistentes a telitromicina. Conclusión. La frecuencia de los mecanismos de resistencia a macrólidos en Canarias es diferente a la del resto de España, en particular en Lanzarote, con un predominio del gen mefA/E (80% de las cepas, todas ellas del serogrupo 14) (AU)

Background. Macrolide resistance in Streptococcus pneumoniae is coded by the ermB and mefA/E genes. The aim of this study was to determine the status of macrolide-resistance, the molecular mechanisms involved, the serogroup relationships, and the level of co-resistance in S. pneumoniae isolates from Gran Canaria and Lanzarote, in the Canary Islands, Spain. Methods. Macrolide resistance phenotypes were investigated in 261 S. pneumoniae clinical isolates over a two-year period (2004 and 2005). Genotypes were determined by PCR (detection of ermB and mefA/E genes). Results. Overall macrolide resistance was 40.6% (106 isolates); 79.2% (84) of resistant isolates presented the MLSB phenotype (98.8% harbored the ermB gene), with a predominance of serogroup 19, and 20.8% (22) presented the M phenotype (77.3% displayed the mefA/E gene), all associated with serogroup 14. Worthy of note, the M phenotype was found in 8 invasive isolates from Lanzarote (80%) all from serogroup 14. The ermB and mefA/E genes were detected in 7 isolates belonging to serogroup 19. Absence of co-resistance was observed most frequently in serogroup 14 (66.7%). Co-resistance with penicillin G, tetracycline, and trimethoprim-sulfamethoxazole was associated with serogroup 19 (36.8%). Two isolates (0.8%) were resistant to telithromycin. Conclusion. The frequency of macrolide resistance mechanisms in the Canary Islands is different from that observed in the rest of Spain, particularly in Lanzarote, where 80% of isolates harbored the mefA/E gene and belonged to serogroup 14 (AU)