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BMC veterinary research2023; 19(1); 210; doi: 10.1186/s12917-023-03772-4

Molecular and sequencing study and identification of novel SeM-type in beta-hemolytic streptococci involving the upper respiratory tract in Iran.

Abstract: Beta-hemolytic streptococci involving the upper respiratory tract cause strangles and strangles-like diseases in horses and cause severe economic damage to the equestrian club each year. Therefore, careful epidemiological study of these bacteria, evaluation of phylogenetic connections and SeM-typing can be useful to determine the source and epidemiological characteristics of the disease outbreak. Isolates were analyzed using molecular and phylogenetic methods and to determine antibiotic resistance pattern in Iranian isolates. Molecular and phylogenetic methods were used to evaluate Iranian streptococcal isolates, and the similarity of the Iranian SeM-97 sequence with other alleles was assessed using the Neighbor-joining method with the Kimura 2 Parameter statistical model. The amino acid sequence of this gene was compared with the predicted SeM-3 reference amino acid sequence (FM204883) using MEGA 7 software. Results: One type of SeM was found among streptococcal isolates. This type (SeM-97) was reported for the first time and was a new SeM. The relationship between streptococcal isolates and age, sex, race, clinical signs and geographical area was investigated. A significant relationship was observed between streptococcal isolates with age variables and clinical symptoms. Conclusions: In our study, a Streptococcus equi subsp. equi genotype was identified. The 97 allele of this gene has not been officially reported anywhere and is only registered in the Public databases for molecular typing and microbial genome diversity (PubMLST)-SeM database by Katy Webb. This was the first isolate reported and registered in the mentioned database. The isolate (Tabriz61) had the SeM-97 allele with clinical signs including mucopurulent discharge, abnormal sounds in lung hearing, warmth and enlargement or discharge and abscess of retropharyngeal lymph node and fever. This isolate was sensitive to penicillin, meropenem, ampicillin, cefotaxime, tetracycline, erythromycin, azithromycin, chloramphenicol, enrofloxacin and ciprofloxacin antibiotics and resistant to trimethoprim-sulfamethoxazole and gentamicin antibiotics.
© 2023. BioMed Central Ltd., part of Springer Nature.
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Publication Date: 2023-10-17 PubMed ID: 37848882PubMed Central: PMC10580511DOI: 10.1186/s12917-023-03772-4Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Overview

  • This study identified a new molecular type (SeM-97) of beta-hemolytic Streptococcus equi subsp. equi isolated from the upper respiratory tract of horses in Iran.
  • The research explored the genetic characteristics, epidemiological associations, and antibiotic resistance profiles of these bacterial isolates.

Background and Objectives

  • Beta-hemolytic streptococci cause strangles and strangles-like diseases in horses, which lead to significant economic losses in equestrian settings annually.
  • Understanding the molecular and phylogenetic diversity of these bacteria helps track their epidemiology and sources during outbreaks.
  • The study aimed to:
    • Analyze Iranian isolates of streptococcal bacteria using molecular sequencing and phylogenetic tools.
    • Identify the SeM gene types present and detect any new alleles.
    • Assess patterns of antibiotic resistance among these isolates.
    • Evaluate relationships between bacterial isolates and host or regional factors such as age, sex, clinical signs, and geography.

Methods

  • Collection of streptococcal bacterial isolates from the upper respiratory tract of horses exhibiting clinical symptoms.
  • Molecular typing focused on the SeM gene, which encodes an M-like protein important for virulence and immune evasion.
  • Sequencing the SeM gene and comparing sequences with known alleles using:
    • Neighbor-joining phylogenetic analysis with the Kimura 2 Parameter model for genetic similarity.
    • MEGA 7 software to compare amino acid sequences against reference SeM-3.
  • Investigation of associations between bacterial isolate types and epidemiological factors such as age, sex, race, clinical signs, and location.
  • Antibiotic susceptibility testing to determine resistance and sensitivity profiles.

Key Findings

  • Identification of a single SeM gene type in Iranian isolates, designated as SeM-97.
  • SeM-97 represents a novel allele not previously reported or described in published literature.
  • This allele is registered in the PubMLST SeM database, credited to Katy Webb, marking the first official entry.
  • The particular isolate named Tabriz61 carried SeM-97 and corresponded with clinical signs such as:
    • Mucopurulent nasal discharge
    • Abnormal lung sounds
    • Warmth and enlargement or discharge/abscess of the retropharyngeal lymph node
    • Fever
  • There was a statistically significant correlation between the presence of streptococcal isolates and variables including:
    • Age of the horses
    • Clinical symptoms observed
  • Antibiotic resistance profile of isolate Tabriz61 showed sensitivity to a broad spectrum of antibiotics:
    • Penicillin
    • Meropenem
    • Ampicillin
    • Cefotaxime
    • Tetracycline
    • Erythromycin
    • Azithromycin
    • Chloramphenicol
    • Enrofloxacin
    • Ciprofloxacin
  • The isolate was resistant to:
    • Trimethoprim-sulfamethoxazole
    • Gentamicin

Conclusions and Significance

  • The study reports the first identification of a novel SeM allele (SeM-97) in Streptococcus equi subsp. equi from Iran, expanding the genetic diversity known for this pathogen.
  • Understanding this local genetic variation can aid in more precise epidemiological tracking and disease control efforts in equine populations.
  • The correlation between bacterial isolates and clinical signs emphasizes the clinical relevance of these molecular findings.
  • Knowledge of antibiotic sensitivities assists veterinarians in selecting effective treatments and combating antimicrobial resistance.
  • This molecular characterization enriches public databases, supporting future research and surveillance worldwide.

Cite This Article

APA
Moghaddam S, Lotfollahzadeh S, Salehi TZ, Hassanpour A, Manesh HT, Tamai IA. (2023). Molecular and sequencing study and identification of novel SeM-type in beta-hemolytic streptococci involving the upper respiratory tract in Iran. BMC Vet Res, 19(1), 210. https://doi.org/10.1186/s12917-023-03772-4

Publication

BMC veterinary research
ISSN: 1746-6148
NlmUniqueID: 101249759
Country: England
Language: English
Volume: 19
Issue: 1
Pages: 210
PII: 210

Researcher Affiliations

Moghaddam, Sina
  • Department of Internal Medicine, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.
Lotfollahzadeh, Samad
  • Department of Internal Medicine, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran. Samadlzadeh@ut.ac.ir.
Salehi, Taghi Zahraei
  • Department of Microbiology and Immunology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.
Hassanpour, Ali
  • Department of Clinical Sciences, Faculty of Veterinary Medicine, Tabriz Medical Science Branch, Islamic Azad University, Tabriz, Iran.
Manesh, Hamid Tavanaei
  • Department of Internal Medicine, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.
Tamai, Iraj Ashrafi
  • Department of Microbiology and Immunology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.

MeSH Terms

  • Streptococcus
  • Anti-Bacterial Agents / pharmacology
  • Streptococcal Infections / epidemiology
  • Streptococcal Infections / veterinary
  • Streptococcal Infections / microbiology
  • Horse Diseases / epidemiology
  • Horse Diseases / microbiology
  • Trachea
  • Horses
  • Streptococcus equi / genetics
  • Animals
  • Phylogeny
  • Iran / epidemiology

Conflict of Interest Statement

The authors report no conflict of interest.

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Citations

This article has been cited 2 times.
  1. Pınar O, Çelik Doğan C, Aktaran Bala D, Kumaş C, Mete A. Analysis of the presence of Beta-hemolytic streptococci and cytological profiles in horse tracheal lavage samples with diverse clinical respiratory symptoms.. BMC Vet Res 2025 Oct 2;21(1):558.
    doi: 10.1186/s12917-025-05011-4pubmed: 41039541google scholar: lookup
  2. Abdul-Latif SAK, Yousif AA. Molecular study of Streptococcus equi isolated from horses with strangles in Iraq.. Open Vet J 2025 Feb;15(2):731-737.
    doi: 10.5455/OVJ.2025.v15.i2.22pubmed: 40201849google scholar: lookup
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