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Frequency and molecular characterization of invasive isolates of Streptococcus pneumoniae serotypes 6C and 6D in
Eliana Liseth Parra1, Carolina Duarte1, Karina Rodríguez1
1Grupo de Microbiología, Instituto Nacional de Salud, Colombia.
Introduction:
Serogroup 6 of Streptococcus pneumoniae initially consisted of the 6A and 6B serotypes, but in recent years, the 6C and 6D serotypes were reported. The aim of this study was to determine the frequency and molecular characterization of invasive S. pneumoniae isolates serotypes 6C and 6D in Colombia, from 1994 to 2013.
Methodology:
All the isolates recovered during the surveillance from 1994 to 2013, and identified as 6A or 6B, were re-tested to detect the serotypes 6C and 6D. The serotyping was performed using the Quellung reaction and PCR. The susceptibility testing was performed on penicillin, erythromycin, ceftriaxone, trimethoprim/sulfamethoxazole, chloramphenicol, tetracycline and vancomycin. Molecular typing was performed using pulsed-field gel electrophoresis and multilocus sequence typing.
Results:
From a total of 271 and 350 isolates serotyped previously as serotypes 6A and 6B, 61 (22.5%) and 15 (4.3%) were recognized as 6C and 6D, respectively. Isolates presented with low resistance to antimicrobials. Serotype 6C isolates were mainly associated with ST9007 (42.6%) and ST9008 (19.7%), and serotype 6D isolates with ST1135 (80%).
Conclusion:
This study showed the circulation of serotype 6C and 6D in Colombia between 1994 and 2013, information that is important to determine the dynamics of these recently described serotypes.
Insights
The study identified Streptococcus pneumoniae serotypes 6C and 6D circulating in Colombia between 1994 and 2013. This research provides crucial data on the prevalence and molecular characteristics of these newly identified serotypes.
Area of Science:
- Microbiology
- Infectious Diseases
- Epidemiology
Background:
- Serogroup 6 of Streptococcus pneumoniae previously included serotypes 6A and 6B.
- Recently, serotypes 6C and 6D have been identified, necessitating further investigation.
- Understanding the epidemiology of these new serotypes is crucial for public health.
Purpose of the Study:
- To determine the frequency of Streptococcus pneumoniae serotypes 6C and 6D in Colombia.
- To perform molecular characterization of these invasive isolates.
- To analyze antimicrobial susceptibility patterns.
Main Methods:
- Retrospective analysis of Streptococcus pneumoniae isolates from 1994-2013.
- Serotyping using Quellung reaction and PCR.
- Antimicrobial susceptibility testing and molecular typing (PFGE, MLST).
Main Results:
- 61 (22.5%) of previously 6A isolates were reclassified as 6C.
- 15 (4.3%) of previously 6B isolates were reclassified as 6D.
- Serotype 6C associated with ST9007/ST9008; Serotype 6D associated with ST1135. Low antimicrobial resistance observed.
Conclusions:
- Demonstrated circulation of Streptococcus pneumoniae serotypes 6C and 6D in Colombia (1994-2013).
- Provides essential epidemiological data for understanding the dynamics of these emerging serotypes.
- Highlights the importance of ongoing surveillance for novel serotypes.
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