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Updated: Oct 10, 2025
Genome-wide Gene Deletions in Streptococcus sanguinis by High Throughput PCR
Published on: November 23, 2012
Beta hemolysin gene of Staphylococcus phage 3AJ_2017 genome is a suitable molecular marker for identification and
Silviane A Miruka1, Gabriel O Aboge1,2, Rosaline W Macharia1
1Center for Biotechnology and Bioinformatics, College of Biological and Physical Sciences, University of Nairobi, Nairobi, Kenya.
Background:
Staphylococcus aureus cause diseases both in humans and animals. These diseases range from mild to fatal infections thus necessitating development of a specific molecular method for detection of pathogenic S. aureus.
Objectives:
To identify and analyze genetic profile of pathogenic S. aureus using bacteriophage based genetic biomarkers.
Methods:
Using culture and biochemical methods, 148 S. aureus (87 %) were isolated from 170 raw milk samples taken from 10 dairy farms in Marsabit and Isiolo counties in Northern Kenya between June 2016 and February 2017. The samples were collected directly from dairy lactating cows previously diagnosed with S. aureus in a follow-up study. The isolates were analyzed by PCR and sequencing of beta hemolysin (hlb) gene. The genetic relationship between five Kenyan S. aureus isolates and five isolates previously identified was inferred.
Results:
From the 96 isolates screened for hlb gene, 75 (78.1%) tested positive. Some of the positive isolates yielded a band size of 975 bp, while others 1100 bp. Through Basic Local Alignment Search Tool (BLAST) search analysis, the two different band sizes (975 bp and 1100 bp) were both confirmed to be hlb gene from S. aureus isolates indicating that the difference in band size may have been due to deletions that were detected in the 975 bp hlb gene. Some S. aureus isolates from Kenya appeared to be closely related to isolates from other parts of the world, while some showed a distant relationship.
Conclusions:
Phage-derived hlb gene is a suitable molecular marker for detection of pathogenic S. aureus.
Insights
The beta hemolysin (hlb) gene, derived from bacteriophages, serves as an effective molecular marker for identifying pathogenic Staphylococcus aureus in raw milk. This method aids in detecting the bacteria in animal and human health contexts.
Area of Science:
- Veterinary Microbiology
- Molecular Diagnostics
- Food Safety
Background:
- Staphylococcus aureus poses significant health risks in both humans and animals, causing a spectrum of diseases.
- The need for precise molecular detection methods for pathogenic S. aureus is critical for effective disease management.
Purpose of the Study:
- To identify and characterize pathogenic Staphylococcus aureus strains.
- To analyze the genetic profile of S. aureus using bacteriophage-derived genetic biomarkers.
Main Methods:
- Isolation and biochemical identification of S. aureus from raw milk samples collected from dairy farms in Kenya.
- Polymerase Chain Reaction (PCR) and sequencing of the beta hemolysin (hlb) gene.
- Phylogenetic analysis to infer genetic relationships between S. aureus isolates.
Main Results:
- Over 78% of screened S. aureus isolates tested positive for the hlb gene.
- Two distinct band sizes (975 bp and 1100 bp) for the hlb gene were observed, attributed to deletions in the shorter variant.
- Kenyan S. aureus isolates exhibited varying degrees of genetic relatedness to global isolates.
Conclusions:
- The bacteriophage-derived beta hemolysin (hlb) gene is a validated molecular marker for detecting pathogenic Staphylococcus aureus.
- This finding supports the development of advanced diagnostic tools for S. aureus surveillance.
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