TREATMENT OF BOVINE MASTITIS WITH APPROPRIATE ANTIMICROBIALS BASED ON IN-VITRO SENSITIVITY TEST AND ACRIDINE ORANGE PHAGOCYTE FUNCTION TEST
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Date
2013
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Birsa Agricultural University, Kanke, Ranchi, Jharkhand
Abstract
The present study was aimed at selection of most appropriate antibiotic capable of killing extracellular as well as intracellular phagocytosed bacteria.
The study was conducted on 150 cases of bovine mastitis. Milk samples from affected quarters of cows were collected aseptically in a clean and sterilized capped vial. The clinical cases of mastitis were confirmed by different tests. The confirmed clinical samples of mastitis were subjected for identification of mastitis causing organisms by different microbiological tests. In-vitro culture and sensitivity test was carried out on so identified organisms to know the spectrum of sensitive antibiotics for individual cases of mastitis. Among such spectrum of antibiotics, those antibiotics which were capable of killing extra cellular organisms as well as intracellular phagocytosed organisms along with its ability to enhance phagocytosis was further selected with the help of Acridine orange phagocytic assay test for treatment of such mastitic cases. The outcome of treatment was assessed on daily basis by presence or absence of mastitis on the basis of SCC of milk samples collected
after treatment. Therapeutic efficacy of antibiotics selected with the help of phagocytic assay was evaluated by comparison with the outcome of mastitis treated with antibiotics showing highest sensitivity with in-vitro culture and sensitivity test.
Bacteriological study revealed that incidence of bovine mastitis due to gram positive organism was higher (61.76%) in which Streptocouus aureus mastitis was most prevalent (37.25%). The incidence of bovine mastitis due to gram negative organism was much lower (17.65%) in which E. coli (11.76%) and Pseudomonas spp. (6.86%) were more prevalent.
As far as variation in consistency of milk due to mastitis is concerned, in majority of cases milk sample of bovine mastitis showed normal consistency without flakes. Considerable number of samples showed serous or thick consistency in which presence of flakes was a consistent feature. Thick or purulent consistency was more commonly observed in pseudomonas and staphylococcal mastitis.
Comparative study of various diagnostic tests revealed SCC as highly sensitive, more specific and had highest efficacy in mastitis diagnosis.
The pH of milk samples in majority of cases ranged in between 6.4 to 7.0. Development of significant alkalinity in milk was more prominent in Staphylococcus aureus and other staphylococcal mastitis.
Electrical conductivity below normal range was never found with any of the known isolates however it was seen in samples having no isolates. In comparison to gram negative organisms, the gram positive organism predominantly staphylococcus aureus was noticed with higher rise in electrical conductivity. Hence, it was concluded that electrical conductivity can be used in diagnosing staphylococci specially mastitis caused by staphylococcus aureus infection.
Higher chloride content was the prominent features of the mastitis causing isolates. Mastitis due to gram positive organism was always noticed with high rise of chloride content in comparison to gram negative organism where slight rise was noted. Hence, it was noted that electrical conductivity can be used in diagnosing of mastitis due to gram positive organism.
High somatic cell count was consistently found in milk sample from case of bovine mastitis, suggesting it to be a good marker for mastitis diagnosis. The rise in SCC was most significant in streptococcal mastitis.
The most effective antimicrobial agents for both gram positive and gram negative micro-organism was recorded to be Ciprofloxacin, followed by Ceftriaxone, Enrofloxacin, Gentamycin, Amoxicillin+Sulbactam, Ampicillin+Cloxacillin and Ceftiofur sodium in descending order of efficacy. Drug like Ampicillin+Cloxacillin followed by Amoxicillin+Sulbactam, Gentamycin, Ceftriaxone, Ciprofloxacin, Enrofloxacin and Ceftiofur sodium were mostly found to be resistant in nature.
The selection of antimicrobials after culture and sensitivity test should be based on its ability to cross blood tissue barrier for mammary parenchyma, have lipophilicity and ability to work in alkaline pH.
No specific trend of organism specific leukocyte cell death, phagocytosis and intracellular bacterial killing ability of different antibiotics was noted as a result of individual animal-phagocytic cell-antibiotic interactions.
A variable effect of different antibiotics on percentage leukocyte cell death, intracellular bacterial killing and average phagocytosis was highly noted which warrants use of acridine orange phagocyte function test for appropriate selection of antibiotics.
While selecting antibiotics, acridine orange phagocyte function test was able to give suitable antibiotics even for those animals which fail to show bacterial growth during in-vitro culture and sensitivity test due to pre-treatment of animals with antibiotics.
Early and complete recovery was noted in animal treated with antibiotics selected on the basis of acridine orange phagocyte function test which showed superiority over in-vitro sensitivity test for selection of appropriate antibiotics.
Use of both intramuscular and intramammary route for antibiotic treatment showed better results over use of these routes alone.
Treatment will be more fruitful and effective if the antimicrobial enhances the phagocytic potential of phagocytic cells, least toxic to cells and facilitate both intra and extracellular killing of causative agents.
Thus, by critically analyzing the various features of bovine mastitis, it could be concluded that inclusion of the parameters in the routine laboratory testing of the milk samples will be of immense help in assessing the severity of infection, presence of causative agents in the milk sample and selection of appropriate antimicrobials for effective treatment as well as assessment of the duration of treatment and fate of disease (mastitis). Thus, the present study has got definite applied value and is highly economical to farmers particularly in case of chronic mastitis and in a situation of sterile culture of mastitic milk samples.
The acridine orange phagocyte function test has potential to emerge as an important adjunct test for appropriate selection of antimicrobials even in sterile milk which shows no isolates on the basis of antibiotic sensitivity test. This method of diagnosis is highly economical and specific for selection of antibiotics for the treatment of mastitis as this test takes least time.
Description
TREATMENT OF BOVINE MASTITIS WITH APPROPRIATE ANTIMICROBIALS BASED ON IN-VITRO SENSITIVITY TEST AND ACRIDINE ORANGE PHAGOCYTE FUNCTION TEST
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