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Published on: September 11, 2020
Molecular Epidemiology of Multidrug-Resistant Pneumococci among Ghanaian Children under Five Years Post PCV13 Using
Richael O Mills1,2, Mohammed R Abdullah1, Samuel A Akwetey2,3
1Department of Molecular Genetics and Infection Biology, Interfaculty Institute for Genetics and Functional Genomics, Center for Functional Genomics of Microbes, University of Greifswald, 17487 Greifswald, Germany.
Insights
Multidrug-resistant pneumococci, particularly international clones, are prevalent in vaccinated Ghanaian children. This highlights the urgent need for enhanced surveillance of antibiotic resistance in Streptococcus pneumoniae.
Area of Science:
- Microbiology
- Molecular Epidemiology
- Public Health
Background:
- Antibiotic resistance in Streptococcus pneumoniae (pneumococci) is a significant contributor to child mortality globally.
- Understanding the molecular characteristics of multidrug-resistant (MDR) pneumococci is crucial for effective public health interventions, especially in vaccinated populations.
Purpose of the Study:
- To investigate the molecular features of MDR pneumococci strains isolated from healthy, vaccinated children under five years of age in Cape Coast, Ghana.
- To identify specific antibiotic resistance and virulence genes, and to analyze the molecular epidemiology of these isolates.
Main Methods:
- Isolation and selection of 43 MDR pneumococcal strains from nasopharyngeal carriage samples of children.
- Serotyping using multiplex PCR and Quellung reaction.
- Antimicrobial susceptibility testing via E-test or disk diffusion.
- Detection of virulence and antibiotic resistance genes using PCR.
- Molecular typing through multilocus sequence typing (MLST).
Main Results:
- Predominant vaccine serotypes were 23F and 19F. All isolates possessed the lytA and pavB virulence genes.
- High resistance rates (>90%) were observed for penicillin, tetracycline, and cotrimoxazole, with 100% of isolates carrying the tetM gene.
- MLST identified international antibiotic-resistant clones, including ST156 (Spain9V-3) and ST802, alongside five novel sequence types.
Conclusions:
- The prevalence of multidrug-resistant pneumococci, including international clones, in vaccinated children in Ghana is a significant public health concern.
- Continuous monitoring and robust surveillance systems are essential to track the emergence and spread of antibiotic-resistant pneumococcal strains.
Abstract:
Antibiotic resistance in pneumococci contributes to the high pneumococcal deaths in children. We assessed the molecular characteristics of multidrug-resistant (MDR) pneumococci isolated from healthy vaccinated children under five years of age in Cape Coast, Ghana. A total of 43 MDR isolates were selected from 151 pneumococcal strains obtained from nasopharyngeal carriage. All isolates were previously serotyped by multiplex PCR and Quellung reaction. Susceptibility testing was performed using either the E-test or disk diffusion method. Virulence and antibiotic resistance genes were identified by PCR. Molecular epidemiology was analyzed using multilocus sequence typing (MLST). Vaccine-serotypes 23F and 19F were predominant. The lytA and pavB virulence genes were present in all isolates, whiles 14-86% of the isolates carried pilus-islets 1 and 2, pcpA, and psrP genes. Penicillin, tetracycline, and cotrimoxazole resistance were evident in >90% of the isolates. The ermB, mefA, and tetM genes were detected in (n = 7, 16.3%), (n = 4, 9.3%) and (n = 43, 100%) of the isolates, respectively. However, >60% showed alteration in the pbp2b gene. MLST revealed five novel and six known sequence types (STs). ST156 (Spain9V-3) and ST802 were identified as international antibiotic-resistant clones. The emergence of international-MDR clones in Ghana requires continuous monitoring of the pneumococcus through a robust surveillance system.
