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Isolation of High Level Macrolide Resistant Bordetella pertussis Without Transition Mutation at Domain V in Iran
Bahman Mirzaei1, Zakaria Bameri1, Ryhane Babaei1
1Department of Bacteriology, Pasteur Institute of Iran, Tehran, IR Iran.
Background:
Bordetella pertussis, as a causative agent of whooping cough, due to the annual rise y of infection cases, failure of prophylaxis and treatment by macrolides, is considered as the new concern in the health care system.
Objectives:
The main objective of this study was the determination of single nucleotide polymorphisms (SNPs) at domain V, as the main binding site for macrolides, following the identification of high level macrolides resistant B. pertussis.
Materials And Methods:
Following the identification of 11 recovered B. pertussis isolates, from a total of 1084 nasopharyngeal swabs, by using the biochemical and molecular methods, the activities of erythromycin, azithromycin and clarithromycin antibiotics against the recovered isolates were examined. Subsequently, A-G transition mutations in domain V were analyzed by molecular techniques, such as Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) and sequencing.
Results:
After susceptibility testing, one strain was detected as a high level macrolide resistant B. pertussis (Erythromycin = 128 μg/mL, Clarithromycin > 256 μg/mL). After sequencing and PCR-RFLP methods, transition mutations in positions 2047 and 2058 of the mentioned domain were not observed.
Conclusions:
Although previous studies have shown that A-G transition mutations in 23 SrRNA gene (domain V) are the main reason for the occurrence of high level macrolides resistance in B. pertussis, however, the mentioned single nucleotide polymorphisms (SNPs) have not been detected in our resistant strain. This is the first report of high level macrolide resistant B. pertussis, without SNPs in domain V, in Iran.
Insights
High-level macrolide-resistant Bordetella pertussis was identified in Iran. This strain, causing whooping cough, lacked the common SNPs in domain V, challenging existing resistance mechanisms.
Area of Science:
- Microbiology
- Genetics
- Infectious Diseases
Background:
- Bordetella pertussis causes whooping cough, with increasing infections and treatment failures.
- Macrolide antibiotics are failing in prophylaxis and treatment, posing a healthcare concern.
- Identifying resistance mechanisms is crucial for effective whooping cough management.
Purpose of the Study:
- To identify single nucleotide polymorphisms (SNPs) in domain V of B. pertussis.
- To investigate macrolide resistance mechanisms in B. pertussis isolates.
- To analyze macrolide resistance in a high-level resistant strain from Iran.
Main Methods:
- Biochemical and molecular identification of B. pertussis isolates from nasopharyngeal swabs.
- Antibiotic susceptibility testing for erythromycin, azithromycin, and clarithromycin.
- Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) and sequencing to analyze domain V mutations.
Main Results:
- One B. pertussis isolate exhibited high-level macrolide resistance (Erythromycin = 128 μg/mL, Clarithromycin > 256 μg/mL).
- No A-G transition mutations (SNPs) were detected at positions 2047 and 2058 in domain V of the resistant strain.
- This represents the first report of high-level macrolide-resistant B. pertussis without domain V SNPs in Iran.
Conclusions:
- The common A-G transition mutations in the 23S rRNA gene (domain V) are not the sole cause of high-level macrolide resistance in B. pertussis.
- The identified resistant strain lacking domain V SNPs suggests alternative resistance mechanisms may be involved.
- This finding necessitates further research into novel macrolide resistance pathways in B. pertussis.
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