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Updated: Jun 13, 2025
Biosensor for Detection of Antibiotic Resistant Staphylococcus Bacteria
Published on: May 8, 2013
Isolation and characterization of a multidrug-resistant Staphylococcus aureus infecting phage and its therapeutic use
Zhen Xiao1,2, Hongyi Xu1,2, Juan Wang1
1China animal health and epidemiology center, Qingdao 266032, China.
Abstract:
In recent years, the emergence of multidrug-resistant bacteria has limited the selection of drugs for treating bacterial infections, reduced clinical efficacy, and increased treatment costs and mortality. It is urgent to find alternative antibiotics. In order to explore a new method for controlling methicillin-resistant Staphylococcus aureus (S. aureus), this study isolated and purified a multidrug-resistant S. aureus broad-spectrum phage JPL-50 from wastewater. JPL-50 belongs to the Siphoviridae family after morphological observation, biological characterization, and transmission electron microscopy (TEM) fragmentation spectrum analysis. It can cleave 84% of tested S. aureus (168/200), in which 100% of tested mastitis-associated strains (48/48) and 72.04% of MRSA strains (67/93) were lysed. In addition, it has an optimal growth temperature of about 30°C, a high activity within a wide pH range (pH 3-10), and an optimal multiplicity of infection of 0.01. The one-step growth curve shows a latent time of 20 min, an explosive time of 80 min. JPL-50 was 16 927 bp in length and was encoded by double-stranded DNA, with no genes associated with bacterial resistance or virulence factors detected. In a therapeutic study, injection of the phage JPL-50 once and for 7 times in 7 days protected 40% and 60% of the mice from fatal S. aureus infection, respectively. More importantly, JPL-50-doxycycline combination could effectively inhibit host S. aureus in vitro and reduce the use of doxycycline within 8 h. In conclusion, the bacteriophage JPL-50 has a wide lysis spectrum, high lysis rate, high tolerance to extreme environments, and moderate in vivo activity, providing ideas for developing multidrug-resistant S. aureus infections.
Insights
A novel bacteriophage, JPL-50, effectively targets multidrug-resistant Staphylococcus aureus, including MRSA strains. This broad-spectrum phage shows promise as an alternative antibiotic, even in combination therapies.
Area of Science:
- Microbiology
- Bacteriology
- Virology
Background:
- The rise of multidrug-resistant bacteria, particularly methicillin-resistant Staphylococcus aureus (MRSA), poses a significant global health threat.
- Limited treatment options and increasing mortality rates necessitate the urgent development of novel antimicrobial strategies.
- Bacteriophages offer a promising alternative or adjunct therapy against antibiotic-resistant bacterial infections.
Purpose of the Study:
- To isolate and characterize a novel bacteriophage with broad-spectrum activity against multidrug-resistant Staphylococcus aureus.
- To evaluate the therapeutic potential of the isolated bacteriophage, individually and in combination with antibiotics, against S. aureus infections.
- To assess the phage's biological characteristics, genomic features, and safety profile for potential clinical application.
Main Methods:
- Isolation and purification of bacteriophage JPL-50 from wastewater.
- Morphological and biological characterization, including transmission electron microscopy (TEM).
- In vitro lysis spectrum analysis against various S. aureus strains, including MRSA and mastitis-associated isolates.
- Determination of optimal growth conditions (temperature, pH, multiplicity of infection) and growth curve analysis.
- Genomic sequencing to identify resistance genes or virulence factors.
- In vivo therapeutic efficacy studies in a mouse model of S. aureus infection.
- In vitro evaluation of phage-antibiotic combination therapy.
Main Results:
- Bacteriophage JPL-50, belonging to the Siphoviridae family, demonstrated broad-spectrum lytic activity against 84% of tested S. aureus strains.
- JPL-50 achieved 100% lysis of mastitis-associated S. aureus and 72.04% lysis of MRSA strains.
- The phage exhibited optimal activity at 30°C and a wide pH range (3-10), with a latent period of 20 min and burst time of 80 min.
- Genomic analysis revealed a 16,927 bp double-stranded DNA genome with no detected antibiotic resistance or virulence genes.
- In vivo studies showed that JPL-50 administration protected 40-60% of mice from lethal S. aureus infection.
- Combination therapy with doxycycline significantly enhanced S. aureus inhibition in vitro and reduced antibiotic dosage requirements.
Conclusions:
- The bacteriophage JPL-50 is a potent candidate for combating multidrug-resistant S. aureus infections due to its wide lysis spectrum, high efficacy, and environmental tolerance.
- Its safety profile, indicated by the absence of resistance and virulence genes, supports its potential therapeutic use.
- Phage-antibiotic combination therapy presents a synergistic approach to overcome S. aureus resistance and improve treatment outcomes.
- JPL-50 offers a viable alternative or adjunct to conventional antibiotics, addressing the critical need for new strategies against resistant bacteria.
