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Genotyping of Staphylococcus aureus by Ribosomal Spacer PCR RS-PCR
Published on: November 4, 2016
Methicillin resistance and selective genetic determinants of Staphylococcus aureus isolates with bovine mastitis milk
Zohreh Ahangari1, Masoud Ghorbanpoor1, Masoud Reza Seifiabad Shapouri1
1Department of Pathobiology, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran.
Background And Objectives:
Staphylococcus aureus is one of the major causes of bovine mastitis, which can be transmitted from animals to humans. Methicillin-resistant S. aureus (MRSA) isolates are more attentive and if not treated promptly, they can cause death. The aim of this study was to determine the prevalence of methicillin resistance and frequency of selected virulence factors of S. aureus isolates with bovine mastitis milk origin in Ahvaz, southwest of Iran.
Materials And Methods:
During a two-year period (2014-2015), 75 S. aureus isolates were recovered from referred clinical and sub-clinical bovine mastitis milk samples. The isolates were phenotypically investigated for resistance to cefoxitin by Kirby-Bauer method. DNA were analyzed by PCR for mecA and selected genes that encode the virulence factors.
Results:
According to the results, the spa, ebpS, fnb, bbp, clfA, clfB, and cna genes were detected in 98.7, 97.3, 97.3, 86.7, 84, 84 and 65.3% of the isolates, respectively. Among the 75 isolates, only one (1.3%) isolate was methicillin-resistant. Totally, 39 isolates (50.7%) had all of these virulence factors except mecA. The results showed that 96% of the isolates had at least the fnb, ebpS and spa genes, signifying the noteworthy role of these genes in the pathogenesis of S. aureus bovine intra-mammary infection in this area.
Conclusion:
In the present study, the prevalence of mecA was relatively low, possibly indicating that cows do not play a significant role in community-acquired MRSA infection in this area. According to the results, studied virulence factors were somewhat prevalent, bearing in mind the probable risk of transmission of these isolates from cows to humans, especially those that are in close contact with infected cattle. The data presented here can be used for the introduction of a protective vaccine against this infection.
Insights
Methicillin-resistant Staphylococcus aureus (MRSA) is a concern in bovine mastitis. This study found low MRSA prevalence but high virulence factors in Iranian cattle, suggesting potential zoonotic risk.
Area of Science:
- Veterinary Microbiology
- Bacterial Pathogenesis
- Zoonotic Diseases
Background:
- Staphylococcus aureus is a primary cause of bovine mastitis, posing a zoonotic risk.
- Methicillin-resistant S. aureus (MRSA) presents a significant public health challenge.
- Understanding virulence factors is crucial for controlling S. aureus infections in cattle.
Purpose of the Study:
- To determine the prevalence of methicillin resistance in S. aureus from bovine mastitis milk.
- To identify the frequency of specific virulence factors in these S. aureus isolates.
- To assess the potential for transmission of S. aureus from cattle to humans in Ahvaz, Iran.
Main Methods:
- Phenotypic detection of cefoxitin resistance using the Kirby-Bauer method.
- PCR analysis for the mecA gene and selected virulence factor genes (spa, ebpS, fnb, bbp, clfA, clfB, cna).
- Analysis of 75 S. aureus isolates from bovine mastitis milk samples collected between 2014-2015.
Main Results:
- Only one isolate (1.3%) was methicillin-resistant (MRSA).
- High prevalence of virulence factor genes: spa (98.7%), ebpS (97.3%), fnb (97.3%), bbp (86.7%), clfA (84%), clfB (84%), and cna (65.3%).
- 50.7% of isolates possessed all tested virulence factors except mecA; 96% had at least fnb, ebpS, and spa.
Conclusions:
- The low prevalence of mecA suggests cattle may not be a major reservoir for community-acquired MRSA in this region.
- The high prevalence of virulence factors indicates a potential risk for transmission of S. aureus from cattle to humans, particularly those in close contact.
- The findings support the development of targeted vaccines against S. aureus bovine mastitis.
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