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Molecular Microbiology Research (Online) 2012, Vol.2 No.1 1-9
ISSN 1027-5595
http://mmr.sophiapublisher.com
2
intramammary infections (IMI) with extensive fibrotic
change caused by pathogens such as
Staphylococcus
aureus
pose difficult therapeutic problems. It is
unlikely that typical labeled-dose regimens, despite
providing antibacterial concentrations above minimal
inhibitory concentrations (MIC) in milk for 24 to 48
hours, will eliminate the pathogen from infected
mammary glands. In addition, the major
developmental thrust for antibacterials as a treatment
for mastitis has been directed against gram-positive
organisms, particularly staphylococci and streptococci.
Many herds, however, have seen the emergence of
pathogens with greater resistance to antibacterials
such as gram-negative rods and
Mycoplasma bovis
as
a substantial cause of mastitis losses.
2 Etiology
Mastitis causing pathogens includes bacteria, non
bacterial pathogens like mycoplasma, fungi, yeasts
and Chlamydia (Watts, 1988). Still 20-35% cases
remains of unknown causation (Miltenburg et al.,
1996). Susceptibility to the infection attributed 25% to
the environmental factors, 22% to genetic, and 52% to
herd management (Klastrup, 1996). Different
pathogens play role in development of mastitis are
culture negative contributes
-
43%, second to this
Staphylococcus aureus
-
11%,
E. coli
-
8%,
Streptococcus uberis
-
6%, CNS (coagulase negative
staphylococci)
-
5%, rest by Klebsiella, Enterococcus,
Yeast,
A. pyogens
, and other contaminants.
Bovine herpesvirus 2, vaccinia, cowpox, pseudocowpox,
vesicular stomatitis, foot-and-mouth disease viruses,
and bovine papillomaviruses can play an indirect role
in the etiology of bovine mastitis. These viruses can
induce teat lesions, for instance in the ductus papillaris,
which result in a reduction of the natural defence
mechanisms of the udder and indirectly in bovine
mastitis due to bacterial pathogens. Bovine
herpesvirus 1, bovine viral diarrhoea virus, bovine
immunodeficiency virus, and bovine leukaemia virus
infections may play an indirect role in bovine mastitis,
due to their immunosuppressive properties. But, more
research is warranted to underline their indirect role in
bovine mastitis. We conclude that viral infections can
play a direct or indirect role in the etiology of bovine
mastitis; therefore, their importance in the etiology of
bovine mastitis and their economical impact needs
further attention. It is concluded that isolation and
specific identification of the tiological agents were
still one of the most efficient procedures for the
diagnosis of the disease (mastitis), since the
pathogenic organisms were isolated from CMT-
negative quarters (normal). This should be taken into
account in hygiene training to ensure that dairy
practitioners understand the role of mastitis pathogens,
which can serve as food borne disease and illness.
Similarly special attention should be directed towards
the broad environmental factors in order to improve
and enhance proper preventive measures for the disease.
3 Incidences and Economic Importance
The weighted average of incidence of SCM and CM
worked out as 50.47%, 44.92%, 30.74% and 16.9%,
7.71%, 4.89% for crossbreds, local cattle and
buffaloes, respectively. Economic losses associated
with disease incurred from reduced milk yield, loss of
milk sale due to antibiotic residue concerns, cost of
drug, and death in per acute cases (Gruet et al., 2001).
Worldwide losses due to mastitis have been estimated
to be approximately 35 billion US dollars and USA it
self suffers from 1.5
-
2.0 billion US dollar loss
(Wells
et al., 1998).
India having >50% dairy cattle and
buffalo population under influence of mastitis
inflicting a loss of 2809 crores rupees/annum among,
sub clinical mastitis contributes 67.7% (Singh and
Singh, 1994).
4 Why Comman Antibiotic Treatment Gets
Failure
Bovine mastitis treatment failure is common despite
an appropriate choice of antimicrobial. Current
treatments of clinical mastitis during lactation often
have a poorer cure rate than is predicted by
in vitro
sensitivity, especially in the case of
Staphylococcus
aureus
which, as a chronic infection, is responsible for
huge economic losses. Estimates of bacterial cure rate
for
Staph aureus
mastitis
during lactation mastitis fall
between 25% and 50% (Sol et al., 2000).
Antimicrobial resistance of mastitis-causing organisms
(MCOs) is commonly not the precipitating factor in