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Updated: Dec 18, 2025
Capsular Serotyping of Streptococcus pneumoniae by Latex Agglutination
Published on: September 25, 2014
Molecular characterization, antibiotic resistance pattern and capsular types of invasive Streptococcus pneumoniae
Maryam Beheshti1, Fereshteh Jabalameli1, Mohammad Mehdi Feizabadi1
1Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Building No. 7, 100 Poursina St., Keshavarz Blvd, Tehran, 14167-53955, Iran.
Background:
Streptococcus pneumoniae causes serious infections worldwide. The aim of this study was to determine the molecular characteristic, antibiotic resistance pattern and capsular types of invasive S. pneumoniae in Tehran, Iran.
Results:
Of the 44 pneumococcal invasive isolates, 39 (89%) were isolated from children and 5 (11%) from adults. The results show that all pneumococcal isolates were susceptible to linezolid but had varying resistance to trimethoprim-sulfamethoxazole (86%), erythromycin (73%), tetracycline (66%), clindamycin (43%), penicillin (16%), chloramphenicol (14%) and levofloxacin (2%). The range of erythromycin, tetracycline and penicillin MICs were 2 - ≥ 256 μg/mL, 4 - ≥ 48 μg/mL, and 0.047 - ≥ 256 respectively. All of the penicillin resistant isolates were multidrug resistant (MDR) and in addition to penicillin were resistant to tetracycline, erythromycin and trimethoprim-sulfamethoxazole. The most common capsular types detected in 64% of the pneumococcal isolates was 6A/B, 19A, 15A, 23F. The multilocus sequence typing (MLST) of 10 pneumococcal isolates revealed 9 different sequence types (STs), including ST 15139 (capsular type 19A) and ST 15140 (capsular type 23F), which have not previously been reported.
Conclusions:
The study revealed that the S. pneumoniae isolates belonged to diverse capsular types and clones with high rate of resistance to erythromycin, tetracycline, and penicillin.
Insights
This study investigated invasive Streptococcus pneumoniae in Tehran, finding diverse antibiotic resistance patterns and capsular types, with high resistance to erythromycin, tetracycline, and penicillin among isolates.
Area of Science:
- Microbiology
- Infectious Diseases
- Molecular Epidemiology
Background:
- Streptococcus pneumoniae is a significant global pathogen causing severe infections.
- Understanding the characteristics of invasive pneumococcal strains is crucial for public health.
Purpose of the Study:
- To determine the molecular characteristics of invasive S. pneumoniae isolates.
- To analyze the antibiotic resistance patterns of these isolates.
- To identify the capsular types prevalent in Tehran, Iran.
Main Methods:
- Analysis of 44 invasive S. pneumoniae isolates from Tehran.
- Antimicrobial susceptibility testing against various antibiotics.
- Multilocus sequence typing (MLST) for molecular characterization.
- Serotyping to determine capsular types.
Main Results:
- Most isolates (89%) were from children.
- High resistance rates were observed for trimethoprim-sulfamethoxazole (86%), erythromycin (73%), and tetracycline (66%).
- Penicillin resistance was 16%, with resistant strains showing multidrug resistance (MDR).
- Common capsular types included 6A/B, 19A, 15A, and 23F.
- MLST identified 9 distinct sequence types, including two novel STs (ST 15139 and ST 15140).
Conclusions:
- Invasive S. pneumoniae in Tehran exhibit diverse capsular types and genetic clones.
- A high prevalence of resistance to erythromycin, tetracycline, and penicillin was noted.
- The emergence of novel sequence types highlights the dynamic nature of pneumococcal populations.
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