Basic HTML Version
Molecular Microbiology Research (Online) 2013, Vol.3 No.1 1-8
ISSN 1027-5595
http://mmr.sophiapublisher.com
2
mastitis include
Strep. agalactiae, Strep. uberis,
Enterobacter aerogenes, Actinomyces pyogenes, E.
coli, Klebsiella spp.,
certain fungi and yeasts (Gruet et
al., 2001).
Contagious pathogens like
S. aureus
and
Strepto-
coccus agalactiae
(
Str. agalactiae
) are generally
considered the most predominant organisms respon-
sible for mastitis in the dairy herds lacking an
effective mastitis control program (Kheirabadi et al.,
2008; Radostits et al., 2007).
These
etiologic
agents
and
environmental
opportunistic pathogens like
Escherichia coli
(
E. coli
)
are not unusual to the countries with poor standards of
dairy farming system. It is suggested that even in
currently developed countries, before the adoption of
mastitis control strategies like antiseptic teat dipping
and dry period antibiotic therapy, these three
pathogens were the main problem in relation to
mastitis in dairy cows (Bramely and Dodd, 1984).
The importance of contagious mastitis is further
reflected by a review authered by Allore (1983)
wherein she concluded that contagious pathogens (
S.
aureus
&
Str. agalactiae
) and
E. coli
are responsible
for > 75% of the clinical cases of mastitis and
S.
aureus
is the major one among these. These bacterial
species tend to interact with each other and mammary
gland itself which can further aggravate the conditions.
It is evident from the reports of clinical mastitis by
E.
coli
after blitz therapy (Whole herd treatment for
removing
Strep. agalactiae
infections) with anti-
microbials. There might be accidental entrance of
environmental micro-organisms at the time of intra
mammary infusions (Boyer, 1997).
Staphylococci were first discovered by the Scottish
surgeon, Sir Alexender Ogston (1880) and since then
it has been found associated with a myriad of human
and animal diseases. He named the round
microorganism in infected tissue as “S
taphylococcus
”
(Greek staphyle means bunch of grapes; kokkos
means berry). Nocard identified staphylococci from
mastitis in sheep in 1887 and then in 1890, Guillebeau
stated that these organisms were responsible for
mastitis in cattle (Jonsson and Wadstorm, 1993).
Staphylococcus aureus
is one of the significant causes
of udder infection in dairy animals (Sargeant et al.,
1998). Intramammary infections (IMI) with this
pathogen may lead to clinical and sub-clinical mastitis
and is usually associated with the increase in somatic
cell number (SCC).
Staphylococcus aureus
is a
problem in a variety of locations and under different
management styles. Due to small herd size in Pakistan,
dairy cows and buffaloes are hand milked. Contagious
mastitis pathogens, in particular
S. aureus
are
reportedly a problem in hand milked dairy herds
(Oliver et al., 1975).
A perusal of the literature depicted that
S. aureus
is
one of the most infectious pathogenic bacteria causing
bovine mastitis. This organism attacks very quickly to
all types of cells in mammary glands so its control is
challenging. Mastitis associated with
S. aureus
lean
towards sub-clinical and chronic form that leads to
low response to orthodox antibiotic therapy due to
several causes including intracellular localization of
the organism in mammary gland epithelial cells. This
stubborn infection was associated to absenteeism of
the body defense mechanism in which various host
and bacterial dynamics are involved (Oviedo-Boyso et
al., 2007). The chronicity of
S. aureus
infection is
attributed partly at least to the ability of this bacterium
to produce biofilm.
Staphylococcus aureus
is
reportedly responsible for more than 80 percent of
subclinical bovine mastitis with associated pecuniary
loss of US $ 300 per animal per year (De Graves and
Fetrow, 1993; Wilson et al., 1997; Karahan et al.,
2011).
Staphylococcus aureus
usually colonizes in the teat
canal initially. After colonization, the bacteria adhere
to the epithelium of ducts and alveoli in the gland and
starts toxin production. The adherence of bacteria then
stimulate macrophage stimulation and migration of
neutrophils from blood into the milk which will lead
to high somatic cell number (SCC), swelling of the
mammary gland, damage to the host defense system
and epithelial cells (Cucarella et al., 2004). Mostly, the
protracted infections are related with microbial growth
as adhesive colonies enclosed by a large
exopolysaccharide matrix, establishing a biofilm
(Costerton et al., 1999).