Elsevier

Research in Veterinary Science

Volume 102, October 2015, Pages 242-246
Research in Veterinary Science

Rhodomyrtus tomentosa (Aiton) Hassk. leaf extract: An alternative approach for the treatment of staphylococcal bovine mastitis

https://doi.org/10.1016/j.rvsc.2015.07.018Get rights and content

Highlights

  • This finding provided evidence for prevalence of staphylococcal bovine mastitis.

  • Rhodomyrtus tomentosa extract possessed high antibacterial potency against staphylococci.

  • The extract showed anti-protein denaturation activity and HRBC stabilization.

  • The extract could be used to reduce inflammatory injury due to bacterial infection.

  • The extract could be applied as an alternative agent against bovine mastitis.

Abstract

Antibiotic residues in dairy products as well as emergence of antimicrobial resistance in foodborne pathogens have been recognized as global public health concerns. The present work was aimed to study a potent antibacterial extract from natural product as an alternative treatment for staphylococcal bovine mastitis. Staphylococcal isolates (n = 44) were isolated from milk samples freshly squeezed from individual cows. All staphylococcal isolates were resistant to ampicillin, ciprofloxacin, erythromycin, gentamicin, penicillin, except vancomycin. Rhodomyrtus tomentosa leaf ethanolic extract was accessed for its antibacterial activity and anti-inflammatory potential. The extract exhibited profound antibacterial activity against all of staphylococcal isolates with MIC and MBC values ranged from 16–64 μg/ml and 64–> 128 μg/ml, respectively. Moreover, the extract also exerted anti-protein denaturation and human red blood cell membrane stabilizing activity. The results support the use of R. tomentosa extract that could be applied to cure bovine mastitis and to reduce inflammatory injury caused by the bacterial infections.

Introduction

Bovine mastitis is a frequent cause of economic loss in dairy cows, which adversely affects animal health, impinges on quality of milk, and reduces milk production. The disease is defined as inflammation of mammary gland tissue. It is also characterized by abnormalities of udders and changes in milk composition including increase in somatic cell counts (Galal Abdel Hameed et al., 2006). Mastitis begins after organisms pass through the teat canal. Invasion of the teat usually occurs during milking. Major mastitis causing microorganisms are coagulase-negative staphylococci, Staphylococcus aureus, Streptococcus agalactiae, Escherichia coli, Corynebacterium sp., and Klebsiella sp. (Sharma et al., 2012).

S. aureus is one of the most common mastitis pathogens causing contagious and environmental mastitis (Saidi et al., 2013). It is associated with sub-clinical and clinical bovine mastitis. Recently, S. aureus has been recognized as facultative intracellular pathogen by its abilities to adhere and internalization within bovine mammary epithelial cell and phagocytic cells (Atalla et al., 2010). It can produce adherence factors and virulence toxins involved in pathogenesis of bovine cells such as endotoxin, exotoxin, α-toxin, and haemolysin. Intramammary infection of S. aureus is often causing tissue damage and inflammatory process in host (Craven et al., 2009). Moreover, it is also known as one of the most important agents in dairy products by accidentally mixed into bulk milk and can be transmitted to human (Sasidharan et al., 2011).

Emergence of antibacterial resistance in foodborne pathogens has increased mainly as a result from irrational antibiotics used in livestock. The problem of S. aureus bovine mastitis is becoming worse due to widespread of multidrug-resistant strains (Sampimon et al., 2011). There have been reports on staphylococcal isolates obtained from mastitis resistant to existing antibiotics (Unakal and Kaliwal, 2010, Wang et al., 2013). Antibiotic residue and disinfectant agents accumulate in milk due extensive use in the treatment and control of the disease. It adversely affects environment, animal, human health, economy, and international food trade (Galal Abdel Hameed et al., 2006). Several non-traditional antimicrobial agents or medicinal plants have been tested in the recent years, in order to reduce the settlement of antibiotic residue in milk. Rhodomyrtus tomentosa (Aiton) Hassk. is a plant species belonging to the family Myrtaceae. Many recent studies have reported that ethanolic extract of R. tomentosa leaves has pronounced effect against Gram-positive bacteria such as S. aureus, Staphylococcus epidermidis, methicillin-resistant S. aureus (MRSA) (Saising et al., 2008), Streptococcus pyogenes, Streptococcus pneumoniae, Streptococcus mutans, Enterococcus faecalis, Bacillus subtili, and Bacillus cereus (Limsuwan et al., 2009, Voravuthikunchai et al., 2010). However, anti-inflammatory potential of the ethanolic extract has not been studied.

Therefore, the present work was aimed to further investigate the ability of R. tomentosa extract to eradicate staphylococci in bovine mastitis as well as its anti-inflammatory potential.

Section snippets

Bacterial isolation and culture condition

Staphylococcal isolates (n = 44) were isolated from milk samples freshly squeezed from individual cows in dairy farms located in Phatthalung province, Thailand. Identification of isolates was based on colony characteristics on mannitol salt agar (MSA, Merck, Germany), Gram staining, and catalase reaction. Coagulase test was used to differentiate between coagulase-positive and coagulase-negative staphylococcal isolates. Out of 44 isolates, 18 and 26 isolates were identified as coagulase-positive

Antibiotic susceptibility of staphylococcal isolates

Antibiotic resistance patterns of staphylococci to representative drugs from different antibiotic groups were determined (Fig. 1). Antibiotics used for susceptibility testing include ampicillin, ciprofloxacin, erythromycin, gentamicin, penicillin, and vancomycin. All staphylococcal isolates were resistant to most antibiotics, except vancomycin. Moreover, resistance to more than one antibiotic occurred in both of coagulase-positive and coagulase-negative staphylococci. Among the

Discussion and conclusions

In this study, out of 44 isolates of staphylococci obtained from the milk samples, eighteen isolates (40.9%) were identified as coagulase-positive and twenty-six isolates (59.1%) as coagulase-negative. This finding agrees with earlier studies which reported that coagulase-negative staphylococci were predominant over coagulase-positive staphylococci (Taponen and Pyörälä, 2009). Although, coagulase-negative staphylococci infection is relatively widespread and common in subclinical cases, the

Acknowledgments

This work was supported by Research and Researcher for Industries, Ph. D. program, the Thailand Research Fund (Grant no. PHD 56I0006, Fiscal year 2013–2018), the Higher Education Research Promotion and National Research University Project of Thailand, Office of the Higher Education Commission, Ministry of Education, and TRF Senior Research Scholar (Grant No. RTA5880005), the Thailand Research Fund.

References (27)

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