4. Marco Referencial
2.1.4. Aspectos importantes de la pedagogía y rol docente en el aula: una mirada desde diversos
Experimental challenge models can be advantageous when compared to field experiments using natural infections (Newbould, 1974, Poutrel and Lerondelle, 1978, Heald, 1979, Oliver et al., 2003). The advantages are that a smaller number of cows can be involved, results can be obtained rapidly and at lower costs. In addition, the infection can be closely monitored, and through knowing in advance the strain characteristics and it susceptibility to antibiotics, induced infection can be better controlled. At the completion of the trial, researchers are generally able to stop the infections by treatment, thus avoiding unnecessary suffering to the cows (Oliver et al., 2003).
29
Study Objective challengeType of
Bacteria and concentration of the challenge
suspension
Proportion of successful infections in quarters Reference
Efficacy of teat dip Dipping 5x107 CFU/mL
of S. aureus 5x107CFU/mL of Strep agalactiae
10/40 S. aureus in the dip group 30/40 S. aureus in the control group 8/29 S. agalactiae in the
dip group 21/29 in the control group Nickerson, 1996 Boddie and
Efficacy of teat dips
(chlorine and iodine) Dipping 5x10
7 CFU/mL
of S. aureus 5x107CFU/mL of Strep agalactiae
2/58 S. aureus in the dip group 22/58 in the control group 3 and 23 S. agalactiae infections in
dip and control groups respectively Boddie et al., 2000
Efficacy of teat dip
against control Dipping 5x10
7 CFU/mLand of
S. aureusStrep agalactiae
5x107CFU/mL
2.1 and 5% quarters infected with S. aureus and S. agalactiae in the dip group and 15.8 and
14.3% infections in the control groups Boddie et al., 2004
Efficacy of two iodine
dips Dipping 5x10
7 CFU/mL
of S. aureus and 5x107CFU/mL of Strep agalactiae
2.2 and 6.5% quarters infected with S. aureus and S. agalactiae in the dip group and 20.2 and
21.7% infections in the control groups Foret et al., 2003
To monitor CM incidence after challenge and to determine the role of CNS in intramammary infections Dipping 5x107 CFU/ml of S. aureus 5x107CFU/mL of Strep agalactiae
20.95% of CNS uninfected quarters became infected with S. aureus and S. agalactiae.14,97%
of the CNS infected quarters were infected with S. aureus and S. agalactiae after challenge Nickerson and Boddie, 1994
Efficacy of a teat sealant
with chlorhexidine Dipping 7.7 × 10Day 2 8
Day 4
5.4 × 107
Day 16
2.3 × 107
Treated quarters 7/252 (1.5%) 1.2% for the treated with a novel product. Untreated quarters 13/40 (26.8%)
Petrovski et al., 2011a
30 Table 2-3Cont.
Study Objective challengeType of Bacteria and dose Proportion of successful infections in quarters Reference
S. uberis intramammary and subcutaneus vaccines efficacy Intramammary and subcutaneous
300 CFU of S. uberis Intramammary vaccinated: No clinical cases.
All non-vaccinated quarters developed clinical mastitis
Finch et al., 1994
Inmunity response
against E. coli Intramammary 10
4 CFU of E. coli 100% Heyneman et al.,
1990 Infection following a
challenge. Peptococcus
indolicus and
Actinomyces pyogenes
Intramammary 107 CFU/mL of Peptococcus
indolicus
Mid lactation: 2/12 quarters P. indolicus Adv.
Lactation: 8/12 quarters Pept. ind. Dried off:
12/12 at the dry off became infected
Actinomyces pyogenes 9/12 lactating cows and 100% of dry cows Hillerton and Bramley, 1989 Reproductive consequences of experimentally induced mastitis Intramammary 600 to 1000 CFU/ml of S.
uberis 12/19 Challenged (+)=63% 2 culled control cows displaying signs of CM Hockett et al., 2000
Effect of bovine lactoferrin in experimental challenge
Intramammary 1500 CFU of E. coli 100% Kutila et al., 2004
Efficacy of pirlimycin
and usefulness of S.
uberis in experimental model for future
efficacy test
31
Study Objective challengeType of Bacteria and dose Proportion of successful infections in quarters Reference
Determinate the effect of the NEB on the innate immune
response against S.uberis
Intramammary 2500 CFU/ml
S.uberis 100% Moyes et al., 2010
Compare gene expression profile in blood PMN cells between cows in negative energy balance (NEB) cows and positive energy balance (PEB) ones all challenged
with S. uberis
Intramammary 2500 CFU/ml
S. uberis 100% Moyes et al., 2009
Evaluate effectiveness of
intramammary devices models Intramammary 565 CFU/ml 8% case quarters developed mastitis and 4% of the control quarters Nickerson et al., 1990
Determine the effect of impaired tissue of infected
glands on drug excretion
Intramammary Experiment 1: 42x102
Exp 2: 12x103
Exp 3: 30x105
Exp 4: 48x104
Exp 5: 40x109
Exp 1: 50% of the quarters were infected Exp 2-5: 100%
Mercer et al., 1974a
Evaluate the efficacy of danofloxacine after a single
dose intravenously
Intramammary 26 CFU E. coli 20/23 quarters challenged developed
mastitis Poutrel et al., 2008
To study the influence of the month of lactation in mastitis
incidence
Intramammary 500 CFU/ml S. aureus 90% Poutrel and Lerondelle,
32
Table 2-3Cont.
Study Objective challengeType of Bacteria and dose Proportion of successful infections in quarters Reference
To monitor the effects of two therapy regimens on experimental mastitis
Intramammary 1500 CFU of E coli 100% Pyörälä et al., 1994
To monitor the leukocyte and cytokine dynamics
during experimentally
induced S. uberis mastitis
Intramammary 5x108 CFU/ml 16/20 Rambeaud et al., 2003
To evaluate the efficacy of one teat seal containing
lacticin 3147 (a natural bactericide against Streptococcus and Staphylococcus Intramammary. In the teat sinus S. dysgalactiae 1.5x104
CFU/ml 2/35 mast in the seal+ lacticin 4 quarters not 14/33 mastitis in the infused only seal
sealed
Ryan et al., 1999
To evaluate efficacy of
cefaquinome against E. coli
infections
Intramammary 400-750 CFU/ml 100% Shpigel et al., 1997
To Develop a challenge model to study host
response
Intramammary 2.1x106 CFU/ml
33
Study Objective challengeType of Bacteria and dose Proportion of success infections in quarters Reference
To investigate the expression of CD14 on neutrophils and macrophages to determinate their intervention in mastitis resolution
Intramammary S. aureus and S. uberis
(8x106 CFU/ml)
100% Sladek and Rysanek,
2006 To show the effect of carprofen
in induced E. coli mastitis in
primiparous cows
Intramammary 1x104 CFU/ml E. coli 100% Vangroenweghe et al.,
2005 To elucidate early pathogenesis
within the first few hours after
intramammary inoculation of S.
uberis