Linkage of Mastitis in Dairy and Emergence of Antimicrobial Resistance
NeelaMadhav Patnaik1 and Parag Acharya2
1*Ph.D. Scholar, Dairy Extension Division, NDRI, Karnal
2Asst. Prof., Livestock Production and Management, College of Veterinary Science, RampuraPhul, GADVASU, Ludhiana
Corresponding Author- neela.patnaik@gmail.com
SUMMARY
Antimicrobial resistance has emerged to be a health hazard in both human and livestock sectors. The focus of scientific fraternity and policy makers has attracted towards antimicrobial resistance and its impact on health in coming years. Livestock sector has been increasingly seeing the emergent of resistant strains due to increased use of antibiotics in treating even minor diseases. Mastitis is an important disease from economic point of view in dairy sector witnessing widespread antibiotic usage. The critical antimicrobials of 3rd and 4th generation class for humans; currently used in dairy animals can pose increased risk to human health. Reduction of antimicrobial use in dairy animals can essentially be followed by preventing the occurrence of udder diseases. This can be achieved through decrease in new infections and prudent use of antibiotics in treating sick animals. The present article discusses the occurrence of mastitis, usage of antibiotics for treating udder infections and how emergence of antimicrobial resistance can affect both animal and human health.
INTRODUCTION
Globally India is largest milk producer in the world having a huge livestock population of 535.78 million out of which 302.79 million happens to be bovine population (DAHD, 2019). The distribution of livestock among farmers is more egalitarian in nature compared to land holding and livestock sector is growing annually at 6 percent which is much ahead among other agricultural sectors. In India, production of milk is more of a livelihood activity rather than commercial business. Majority (87 percent) of the dairy farmers are small holders or marginal, landless ones with a small herd size of 1-2 animals. Dairy is an integral part of crop-livestock farming highly prevalent in different parts of the country. Dairy helps the farmer in minimizing the risks associated with crop cultivation by providing continuous income flow throughout the year. But this continuous flow of income for farmers is hampered due to incidence of diseases in animals. Mastitis is one such disease which has heavy influence on farmers in particular and dairy industry generally. The concern of mastitis is not restricted to dairy farmers only but extends its consequences on consumers due to increasing antimicrobial resistance; due to excessive use of antimicrobials in mastitis management of milch animals.
Mastitis in Dairy Farms
In case of dairy farming, along with feeding costs; farmers incur huge costs in health care management animals. One such expensive disease in dairy animals is mastitis which is highly contagious; posing great challenges to the dairy farming in India and worldwide.Mastitis is characterised by inflammation of the udder parenchyma tissue with visible pathological changes such as redness, increase in gland temperature and edema of mammary gland. Physical and chemical properties of milk also changes due to mastitis in dairy animals.Mastitis reduces the milk yield and in extreme cases the teats get damaged which is a huge financial loss to farmers. Research has established the loss of milk yield per lactation may range between 100-500 kg per animal (NAAS, 2013). In India, the estimated loss due to these udder infections is more than $120 million. The financial implications of mastitis (clinical or sub-clinical) are low milk yield and poor milk quality; increased veterinary service cost and culling rates.
Kuanget al. (2009) observed that more than 150 microorganisms are involved as causal agents of mastitis. They vary in the route of transmission in reaching the mammary gland and the subsequent disease they cause upon entry. Prime contagious microbes are Streptococcus agalactiae, Staphylococcus aureus, Mycoplasma spp., Escherichia coli, Klebsiella spp., and Streptococcus dysgalactiae which enter the mammary glands through teat canal (Taneja and Sharma, 2019).Identifying the causal organisms of clinical mastitis can help the veterinarians in making appropriate choice of antimicrobial for mastitis management. Antibiotic class most commonly prescribed for treating mastitis are cephalosporins, penicillins and erythromycin.Milch animals in 4th or 5th lactation are more susceptible to udder infections with teats of hind quarters more affected than the fore quarters (Abebeet al., 2016).The environment in which the animals are reared play a crucial role in exposure to the type of bacteria and their ability to resist the infections. Mastitis is more of a management disease as it can be easily controlled by following appropriate practices so that the bacteria do not enter the teat. One such simple management practice is allowing the animal to feed green fodder after milking as it prevent the animal from sitting down thus restricting the entry of microbes to enter the teat canal.
Mastitis Treatment and Antimicrobial Resistance
Treatment of diseases in milch animals primarily uses antimicrobials but mastitis is the most common disease with high antibiotic use for treatment. Heavy dependence on antimicrobials for treating infections in milch animals is widely seen in dairy sector. The therapeutic management of milch animals is carried out during lactation stage but dry cow therapy is comparatively less common in India. Implementation of dry cow therapy is essentially antibiotic treatment on the day of drying off 6 weeks prior to calving. Dry cow therapy has been a proven method in reducing mastitis incidences at field level. Dry cow therapy method helps to eliminate bacterial pathogens from the herd.
Milk contaminated with bacteria is also a reservoir of antibiotic residues. The presence of residues in milk hampers the quality of milk thus making it unsuitable for human consumption and manufacturing milk products. Studies have found that antibiotic residues milk/milk products can enter the food chain of humans; thus affecting human health by transfer of diseases (Kurjogiet al., 2019). Antimicrobial resistance is a phenomenon which occurs when the pathogens are able to overcome the effect of treated antimicrobials which were effective in treating the infections previously(Marin et al., 2017). The excess and indiscriminate use of antibiotics in treating mastitis for long time has aggravated the problem by emergence of resistant strains. The negative impact of these resistant strains has resulted in treatment failures thus prolonging the infection period and treatment. The presence of infection for a long time can also transmit the resistant strains of sick treated animals to other healthy animals of the herd.Antibiotic susceptibility testing (AST) should be routinely performed so as to know the sensitivity pattern prevailing which ensures effective treatment by diagnosing the disease early and correctly.Isolating the bacteria aseptically from milk samples of infected animal is considered as gold standard. Study by Singh et al. (2018) have reported based on AST of bacteria isolates of mastitis milk samples; vancomycin erythromycin, tetracycline, amoxicillin as most resistant drugs whereasciprofloxacin, sparfloxacin, ofloxacin and azithromycin as the most sensitive ones.
CONCLUSION
Antimicrobial resistance is turning out to be an increasing concern worldwide due to increasing human and animal pathogens. Presence of resistant strains in mastitis pathogens can significantly decrease the antimicrobial efficacy, thus affecting both animal and health.However understanding the extent of prevalence and characteristics of resistant pathogens in mastitis of animals in India is still unclear. Much progress is yet to be made in determining the AMR profile of different bacteria isolates obtained from clinical mastitis cases.Initiation of antimicrobial stewardship programs at national level and improved infection control practices at farm level can be a critical factor in tackling the AMR emergence issue in dairy sector.
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