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Updated: Oct 18, 2025
Genotyping of Staphylococcus aureus by Ribosomal Spacer PCR RS-PCR
Published on: November 4, 2016
Human-Associated Methicillin-Resistant Staphylococcus aureus Clonal Complex 80 Isolated from Cattle and Aquatic
Khuliso Ramaite1, Mutshiene Deogratias Ekwanzala1,2,3, John Barr Dewar4
1Department of Environmental, Water and Earth Sciences, Tshwane University of Technology, Arcadia Campus, Pretoria 0001, South Africa.
Background:
Human-associated methicillin-resistant Staphylococcus aureus (HA-MRSA) has mainly been reported in South African pig and chicken farms. The prevalence of antibiotic-resistant genes (ARGs), virulence factors (VFs), and multilocus sequence types (MLSTs) associated with HA-MRSA in cattle farms has not been reported. Consequently, this study characterised LA-MRSA and its spread from cattle farms into the environment.
Method:
Husbandry soil (HS), nearby river water (NRW), animal manure (AM) and animal drinking water (ADW) were collected on and around a cattle farm. Presumptive MRSA isolates were identified from these samples using CHROMagar media and genotyped as MRSA sequence types (STs), selected ARGs, and VFs, using polymerase chain reaction. An MLST-based dendrogram was generated to link the farm MRSA strains with those in a nearby river.
Results:
The prevalence of MRSA was 30.61% for HS, 28.57% for ADW, 22.44% for NRW, and 10.20% for AM. Isolates from HS harboured the highest number of resistant genes, with 100% for mecA, 91.66% for ermA, and 58.33% for blaZ. However, no ermC or tetM genes were detected. MRSA isolates from AM harboured the lowest number of resistant genes. Only sec and seq enterotoxins were found in all the assessed MRSA isolates. MRSA from the farm revealed six STs (ST80, ST728, ST1931, ST2030, ST3247, and ST5440); all of STs belonged to clonal complex 80 (CC80). An MLST-based dendrogram based on the concatenated sequences of MLST genes under the maximum likelihood criterion revealed four clades of amalgamated MRSA isolates from various livestock environmental matrices, including the NRW.
Conclusion:
The results suggest that livestock environmental matrices might be reservoirs of MRSA that could subsequently disseminate through runoff to pollute water resources. Therefore, continued surveillance of HA-MRSA in livestock environments is warranted.
Insights
Livestock environments can harbor methicillin-resistant Staphylococcus aureus (MRSA), potentially spreading antibiotic-resistant genes (ARGs) into water sources. Cattle farms may act as reservoirs for HA-MRSA, necessitating ongoing environmental surveillance.
Area of Science:
- Veterinary Microbiology
- Environmental Science
- Public Health
Background:
- Human-associated methicillin-resistant Staphylococcus aureus (HA-MRSA) is primarily documented in South African pig and chicken farms.
- Limited data exists on the prevalence of antibiotic-resistant genes (ARGs), virulence factors (VFs), and multilocus sequence types (MLSTs) of HA-MRSA in cattle farms.
- This study investigated livestock-associated MRSA (LA-MRSA) and its environmental dissemination from cattle farms.
Purpose of the Study:
- To characterize LA-MRSA in cattle farm environments.
- To determine the prevalence of ARGs and VFs in LA-MRSA isolates.
- To investigate the potential spread of LA-MRSA from cattle farms into the surrounding environment, including water bodies.
Main Methods:
- Samples including husbandry soil (HS), nearby river water (NRW), animal manure (AM), and animal drinking water (ADW) were collected from a cattle farm.
- Presumptive MRSA isolates were identified using CHROMagar media.
- Polymerase chain reaction (PCR) was employed for genotyping MRSA sequence types (STs), selected ARGs, and VFs. An MLST-based dendrogram was constructed to analyze strain relatedness.
Main Results:
- MRSA prevalence was highest in HS (30.61%) and ADW (28.57%), followed by NRW (22.44%) and AM (10.20%).
- HS isolates showed the highest prevalence of ARGs, including 100% for mecA, 91.66% for ermA, and 58.33% for blaZ. No ermC or tetM genes were detected.
- Six STs (ST80, ST728, ST1931, ST2030, ST3247, ST5440), all belonging to clonal complex 80 (CC80), were identified. Enterotoxins sec and seq were present in all isolates. The dendrogram showed four clades of MRSA isolates from environmental matrices, including NRW.
Conclusions:
- Livestock environmental matrices, such as soil and water, may serve as reservoirs for MRSA.
- MRSA can disseminate from cattle farms into water resources via runoff.
- Continuous surveillance of HA-MRSA in livestock environments is crucial for public health protection.
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