Comparison of transformation frequencies among selected Streptococcus pneumoniae serotypes

Joloba, Moses L.; Kidenya, Benson R.; Kateete, David P.; Katabazi, Fred A.; Muwanguzi, Julian K.; Asiimwe, Benon B.; Alarakol, Simon P.; Nakavuma, Jessica L.; Bajaksouzian, Saralee; Windau, Anne; Jacobs, Michael R.

doi:10.1016/j.ijantimicag.2010.03.024

« Previous Next »International Journal of Antimicrobial Agents
Volume 36, Issue 2 , Pages 124-128, August 2010

Comparison of transformation frequencies among selected Streptococcus pneumoniae serotypes

Moses L. Joloba
- Department of Medical Microbiology, Makerere University College of Health Sciences, Upper Mulago Hill Road, P.O. Box 7072, Kampala, Uganda
- These authors contributed equally to this work.
- Corresponding author. Tel.: +256 41 454 1830; fax: +256 41 453 3002.
Benson R. Kidenya
- Department of Medical Microbiology, Makerere University College of Health Sciences, Upper Mulago Hill Road, P.O. Box 7072, Kampala, Uganda
- These authors contributed equally to this work.
- Present address: Weill-Bugando University College of Health Sciences, Mwanza, Tanzania.
David P. Kateete
- Department of Medical Microbiology, Makerere University College of Health Sciences, Upper Mulago Hill Road, P.O. Box 7072, Kampala, Uganda
Fred A. Katabazi
- Department of Medical Microbiology, Makerere University College of Health Sciences, Upper Mulago Hill Road, P.O. Box 7072, Kampala, Uganda
Julian K. Muwanguzi
- Department of Medical Microbiology, Makerere University College of Health Sciences, Upper Mulago Hill Road, P.O. Box 7072, Kampala, Uganda
- Present address: Infectious Disease Research Institute, Queen Mary's School of Medicine, London, UK.
Benon B. Asiimwe
- Department of Medical Microbiology, Makerere University College of Health Sciences, Upper Mulago Hill Road, P.O. Box 7072, Kampala, Uganda
Simon P. Alarakol
- Department of Medical Microbiology, Makerere University College of Health Sciences, Upper Mulago Hill Road, P.O. Box 7072, Kampala, Uganda
- Present address: Department of Biochemistry, Gulu University, Gulu, Uganda.
Jessica L. Nakavuma
- Faculty of Veterinary Medicine, Makerere University, Kampala, Uganda
Saralee Bajaksouzian
- Case Western Reserve University, Cleveland, OH, USA
- University Hospitals Case Medical Center, Cleveland, OH, USA
Anne Windau
- Case Western Reserve University, Cleveland, OH, USA
- University Hospitals Case Medical Center, Cleveland, OH, USA
Michael R. Jacobs
- Case Western Reserve University, Cleveland, OH, USA
- University Hospitals Case Medical Center, Cleveland, OH, USA

Received 4 February 2010; accepted 17 March 2010. published online 17 May 2010.

Abstract

Although there are over 90 serotypes of Streptococcus pneumoniae, antimicrobial resistance is predominantly found in a limited number of serotypes/serogroups, namely 6, 9, 14, 19 and 23. There is no compelling mechanism to account for this restriction. We aimed to determine whether serotypes commonly associated with drug resistance have higher transformation frequencies than those that are susceptible to antimicrobial agents. An in vitro investigation of the genetic transformation frequency of drug-resistant serotypes compared with that of susceptible serotypes under the influence of synthetic competence-stimulating peptides was performed. The transforming DNA was genomic DNA carrying a Tn916-like transposon containing the mefE gene that confers resistance to erythromycin. It was observed that serotypes 6, 9, 14, 19 and 23, which are highly associated with drug resistance, do not exhibit a higher degree of transformation efficiency than other serotypes. These findings suggest that the association of serotype with drug resistance is likely due to prolonged exposure to transforming DNA resulting from longer nasopharyngeal carriage and to a greater selective pressure from antimicrobials, particularly in children. This is the first study to compare the transformation frequencies of pneumococcal clinical isolates using genomic DNA that carries the composite Tn916-like element.

Keywords: Streptococcus pneumoniae, Drug-resistant serotypes/serogroups, Transformation frequency, Tn916 transposon, mefE gene