INTRODUCTION
Mastitis is an inflammation of the mammary glands of dairy cows accompanied
by physical, chemical, pathological and bacteriological changes in milk and
glandular tissue. Bovine mastitis is most costly and has become extremely complex
disease in India. Bovine mastitis is a major disease that affects the dairy
industry. The disease causes significant losses to the dairy industry and affects
milk hygienic and sanitary features. Mastitis is also of nutritional and technological
significance in milk processing as valuable components like lactose, fat and
casein are decreased, while undesirable components like ions and enzymes are
increased (Anakalo et al., 2004).
Mastitis is produced by a variety of pathogenic microorganisms (Hawari
Azmi and Fowzi, 2008). Although, stress and physical injuries may cause
inflammation of mammary glands, infection by invading bacteria or other microorganisms
(fungi, yeast and possibly viruses) is the primary cause of mastitis (Hawari
Azmi and Fowzi, 2008). The mastitic milk carries bacterial toxins. These
toxins are responsible for food poisoning outbreaks and toxigenic syndrome in
humans. They may also contribute to the persistence of bacteria in bovine mammary
glands and increased udder pathogenicity (Moon et al.,
2006).
Bovine mastitis is associated with deteriorated milk quality, significant reduction
in milk yield and increased costs of production. The economic losses from mastitis
due to severe drop in milk production, potential health risks for other animals
and human beings, increased cost of treatment and culling processes, are tremendous.
In addition to economic losses to farmers, effective control of mastitis is
also important from the consumer’s and processor’s point of view,
because milk from affected animals may harbor organisms potentially pathogenic
to humans and the processing of such milk may result in substandard fermented
products (Dhakal et al., 2007). It has been estimated
that the mastitis alone can cause approximately 70% of all avoidable losses
incurred during milk production (Sumathi et al.,
2008). The disease also results in partial or complete damage to udder tissues
and decreases the productive life span of the animal.
Mastitis is considered as one of the major cause of antibiotics use in dairy
animals. Over 135 different microorganisms have been isolated from bovine intramammary
infections (Hawari Azmi and Fowzi, 2008). Bacteria are
one of the major etiological agents of mastitis. Treatment failure in mastitis
is due to indiscriminate use of antibiotics without testing in vitro
sensitivity. This practice increases economic losses due to costly treatment
and also results in development of resistance to antimicrobials. Antibiogram
studies are essential to avoid further complications. Identification of mastitis
causing pathogens and the results of the antibiotic resistance of the isolated
bacteria are important prerequisites for implementation of effective control
of mastitis. Such information is needed not only to treat and control mastitis
but also to support public health concerns in developing countries (Dhakal
et al., 2007). Considering these points in view the present study
was undertaken to identify the mastitic agents and to study current antibiogram
trend of mastitic bacteria in and around Udgir.
MATERIALS AND METHODS
Source of Milk Samples
Milk samples (100) were collected from cattle and buffaloes suffering from
clinical mastitis from different locations in and around Udgir during January
2008 to December 2008. Relevant history of individual animal was recorded.
Isolation and Identification
The bacteria were isolated in pure culture on Nutrient Agar and the Candida
were isolated on Corn Meal Agar (CMA). Further identification of bacteria was
done on the basis of colony characters, staining (Grams) reaction, growth patterns
on Blood Agar and Mac Conkey Agar (i.e., hemolysis and lactose fermentation,
respectively) followed by motility, morphology, arrangements and biochemical
tests (Indol, MR, VP, Citrate and Catalase). Candida was identified by colony
characters on CMA and staining patterns.
Antimicrobial Susceptibility Testing
Minimal Inhibition Concentration (MIC) values of the bacterial organisms
were analyzed for twelve different antimicrobials namely amoxicillin (30 mcg),
ampicillin (25 mcg), ceftriaxone (30 mcg), cephotaxim (30 mcg), chloramphenicol
(30 mcg), cloxacillin (10 mcg), ciprofloxacin (30 mcg), doxycycline (10 mcg),
enrofloxacin (10 mcg), gentamycin (30 mcg), oxytetracycline (30 mcg) and streptomycin
(25 mcg). The disc diffusion method as described previously (Bauer
et al., 1966) was employed and the interpretation was made as per
the interpretation chart provided by the manufacturer of discs depending on
the diameter of zone of inhibition of bacterial growth.
| Table 1: |
Prevalence of mastitic agent from bovines in and around Udgir |
 |
| Table 2: |
Percent sensitivity of bovine mastitic agents to different
antibiotics |
 |
RESULTS
The data analysis of this study showed that the age of all recorded cases ranged in between 5 to 8 years. Amongst hundred milk samples from clinical mastitis, 63% samples revealed bacterial growth and 7% samples revealed fungal (Candida) growth. No growth was evident in 30% samples.
Table 1 shows prevalence of mastitic agents in bovines in and around Udgir. The study indicated that the major prevalent pathogens associated with bovine mastitis in and around Udgir were Escherichia coli (40.00%) followed by Staphylococcus aureus (34.29%), other bacteria (15.71%) and Candida (10.00%) amongst isolated pathogens. The overall prevalence of Escherichia coli in bovine mastitis recorded during this study was 28.00% followed by Staphylococcus aureus (24.00%), other bacteria (11.00%) and Candida (7.00%). Other bacteria include Pasturella (1.43%), Pseudomonas (1.43%), Bacillus (2.87%), Proteus (1.43%) and mixed bacteria (8.57%).
The in vitro antibiogram studies were conducted on 63 samples which exhibited bacterial growth and antifungal therapy was advised for cases showing fungal mastitis. The in vitro antibiogram studies (Table 2) revealed ciprofloxacin to be the most effective drug (69.84%) followed by gentamycin (68.25%), enrofloxacin (58.73%), chloramphenicol (31.75%) and cephotaxim (23.81%). The sensitivity to cloxacillin observed was the lowest (1.59%) followed by ampicillin (3.18%), streptomycin (4.76%), oxytetracycline (7.94%), amoxicillin (9.52%), doxycycline (9.52%) and ceftriaxone (14.29%).
DISCUSSION
The age of all recorded cases ranged in between 5 to 8 years. Sharma
et al. (2007) and Sharma and Prasad (2002)
reported high prevalence of mastitis between 5 to 7 years and above 7 years
of age. Increasing evidence of mastitis with advanced ages was recorded by Hawari
Azmi and Fowzi (2008). They also noticed that the incidence of clinical
and subclinical mastitis was increased with the sixth years old in some herds.
Dhakal et al. (2007) found more incidence of
mastitis in first and second calving which decreased with increased numbers
of calving. The finding of the present study is in accordance with the observations
of above workers with little variations which might be because of different
geographical attributes and individual variation in susceptibility.
In this study the mastitic agents were isolated from 70% cases, while no growth was evident in 30%. The failure of pathogens to grow in vitro in high percentage of samples may be because of premedication of the animals with antibiotics, non-bacterial causes and the type of media that did not support the growth of whole range of bacteria associated with mastitis.
The study revealed Escherichia coli (40%) and Staphylococcus aureus
(34.29%) as the major pathogens causing bovine mastitis. Sharma
and Prasad (2002) recorded 54.50 per % incidence of Staphylococcus in
bovine mastitis, while Shrirame et al. (2002)
recorded more prevalence of Staphylococcus (72.35%). The predominant
bacterial isolates recovered by Sumathi et al. (2008)
from bovine mastitis were Staphylococcus aureus and Escherichia coli
which are in accordance with the present findings. Hawari
Azmi and Fowzi (2008) revealed that Staphylococcus aureus (40.6%)
and Coliforms (26.1%) were the chief aetiological agents responsible
for clinical mastitis. They reported the incidence of Proteus sp. 1.4%
Pseudomonas sp. 4.3%, mixed 7.3% and others 5.8% in clinical mastitis.
These findings support the findings of present study.
The findings of present study showed the highest incidence of Escherichia
coli (40.00%), which is presumably due to the fact that Escherichia coli
is the commonest environmental contaminants, which is closely associated
with hygiene. It becomes pathogenic whenever the hygienic conditions of the
animal or environment become poor. Moreover, the existence of high concentration
of Escherichia coli in milk also indicates the relatively poor quality
of milk, related with substandard hygiene of farm management, milk collection
and processing system. Staphylococci, Pseudomonas and mixed growth were the
second after Escherichia coli. Their presence was also an indication
of sub-standard dairy farming. Higher incidence of Escherichia coli mastitis
may be due to poor hygienic conditions, as Escherichia coli originates
from the cow’s environment and infect the udder via the teat canal (Sumathi
et al., 2008).
The hygiene at milking is of paramount important in control of these infections
because the infections are spread during milking process (Harmon,
1993).
Gentamicin, enrofloxacin, ciprofloxacin and chloramphenicol are not commonly
used for treatment of mastitis in the area of study resulting in higher efficacy
of these drugs. Ciprofloxacin proved to be the drug of choice in this study.
Few workers found highest sensitivity of mastitic agents to enrofloxacin, gentamycine
(Dhakal et al., 2007; Kumar
and Sharma, 2002) and chloramphenecol (Rao et al.,
1989) and least sensitivity to ampicillin (Dhakal
et al., 2007) and cloxacillin (Rao et al.,
1989). Similar antibiogram patterns were reported by Sumathi
et al. (2008) and Choudhuri (2000), while
Anakalo et al. (2004) reported Staphylococcus
aureus and Coagulase Negative Staphylococcus (CNS) as the major mastitis-inducing
pathogens suggestive of a possible development of resistance from prolonged
and indiscriminate usage of beta-lactam antibiotics.
The results of Hawari Azmi and Fowzi, (2008) are not in agreement to the present findings. They found that the 64% isolates, isolated from mastitic milk were sensitive to Tetracycline and 52.8% to Ampicillin.
Amoxicillin, ampicillin, cloxacillin, streptomycin and oxytetracycline are commonly used antibiotics in bovine mastitis. The mastitic bacteria showed resistance to these commonly used antibiotics. Indiscriminate and frequent use of these antibiotics in animals could be the reason for their ineffectiveness against mastitic bacteria. Since, streptomycin has been extensively used along with penicillin for treating mastitis; it may have led to the development of high resistance in bacteria against this antibiotic.
Moreover, due to lack of prophylactic agents, chemotherapy continues to play
a major role in therapeutic management of the disease. For success of treatment
the antibiotic sensitivity test play a major role. Recently higher antibiotics
have been introduced in treatment of both sub-clinical and clinical mastitis
(Sharma et al., 2007). It is believed that infections
with Staphylococcus aureus respond poorly to therapy with antimicrobial
agents, whether given parenterally or via the intramammary route (Moon
et al., 2006). The emergence of antibacterial resistance among pathogens
that affect animal health is of growing concern in veterinary medicine. Antimicrobial-resistant
pathogens in animals have been incriminated as a potential health risk for humans
from possible transmission as foodborne pathogens. Particularly, mastitis is
the single greatest cause of antibacterial use on dairy farms (Moon
et al., 2006).
Because the quality of the milk cannot be improved following extraction from
the cow, production of high quality milk requires an efficient mastitis control
program. Cows with a high prevalence of mastitis are incapable of producing
high quality milk until the inflammation and infection in the udder are brought
under control. This has severe economic implications for the milk producer,
as the milk is no longer marketable and other animals are easily infected. Treatment
and decrease in milk volume also cause considerable losses (Anakalo
et al., 2004). Therefore, establishing an antibiogram of pathogens
is very important from the clinical and economic points of view.
The findings of this study showed the use of higher antibiotics as most effective antibiotic therapy for control of bovine mastitis in and around Udgir area. Since, this study reported overall 7.00% prevalence of fungal mastitis, during antibacterial treatment, the fungal cause shall also be taken into consideration. Further, antibiogram of mastitic milk is suggested before starting the treatment so as to get maximum efficacy of used antibiotics and to prevent the development of resistance to antibiotics due to indiscriminate and frequent use.
Systematic records regarding the epidemiology of bovine mastitis including
status of infection, antibiogram studies and treatment patterns would provide
useful management information to the producer, farmer and veterinarian. This
has been evident from countries where records have been documented regularly
internationally (Anakalo et al., 2004). Thus,
there is a need to routinely investigate and record the epidemiology of bovine
mastitis and antibiogram sensitivity of bacterial isolates in various parts
of India.
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