anti bacterial

1. SCREENING MODELS FOR ANTI MICROBIAL
ACTIVITY
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2.  An antimicrobial is an agent kills m.o’s or inhibits their
growth
 Antimicrobial medicines can be grouped according to the
m.o’s they act primarily against- antibiotics are used to
against bacteria and antifungal against fungi
 Anti bacterial used to treat bacterial infections, toxicity to
humans and other animals from antibacterial is generally
considered low
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3. ANTIBACTERIAL SCREENING MODELS
 MOUSE SYSTEMIC INFECTION MODEL
 RABBIT SKIN BURN INFECTION MODEL
 MOUSE ASCENDING URINARY TRACT INFECTION
MODEL
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4. MOUSE SYSTEMIC INFECTION MODEL
PRINCIPLE:
o The in vivo efficacy of test against mouse systemic infections was
determined with strains of E.coli, Klebsiella pneumoniae,S.aureus.
o Test showed broad –spectrum in vivo activity in the MSI model
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5. REQUIREMENTS:
 Animal :CD-11 CR mice (18-21g)/ 10 mice per gp,5 males
&5 females
 S.c inj 0.5ml 5% mucin
 Diff.doses of test& ref.cpds
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6. PROCEDURE :
• 18-21 g of mice were selected randomly 7 distributed into 21
groups with 5 gps for each cpd and 1 control
• Mice were I.P infected with 0.5ml of a bacterial suspension in 5%
mucin
• Diff.doses of test & reference cpds (saline for the control)were
administerd S.C 15min& 6h after infection, respectively
• Doses of test were 0.32-1.59mg/kg for E.coli infections, 0.1-
0.5mg/kg for K.pneumoniae, 0.16-2.5mg/kg forS.aureus
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7. OBSERVATION:
• Deaths in each gp ED50 & 95% confidence limits were determined
RESULT :
o In general, test showed broad spectrum activity against
gram –ve and +ve bacteria
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8. RABBIT SKIN BURN INFECTION MODEL
PRINCIPLE :
 The skin burn infection study was carried out with 6 male New
Zealand White rabbits infected with bact.suspension
REQUIREMENTS :
 Animal : new Zealand white rabbits (6 male) / 2.5-3kg
 Challenge dose, 1 x 107 CFU/burn wound
 Barium sulfide ZnO Starch paste
 Anesthesia : pentoibarbital Na (30mg/kg of B.W)
 75% et-OH
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9. PROCEDURE :
 6 male white rabbits infected with E.coli
 one day before infection, the back hair of the animals was clipped
and then removed by applying a paste of BaSO4-ZnO starch (2:3:3
wt/wt/wt)
 On the day of infection ,the rabbits were anesthetized by IV inj.of
pentobarbital Na (30mg/kg of BW) and the back skin of the
animals were sterilized with 75% ET-oh.
 7 deep 2nd degree burn wounds ( 6 for admin.cpds and 1 for
control)were then created on the back of each animal by applying a
brass probe (dia 1.8cm , heated to 100°C for 10s
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10.  15 min later 0.1ml (challenging dose 1x10⁷CFU/burn wound) of
an E.coli suspension in saline was I.C injected into each wound%&
home made cap used for protecting the wound
 1 hr after the burning 0.4ml of diff.cpd soln or saline (for the
control) was administered to the corresponding wound by loading it
onto a sterile gauze patch of the same size as the burn wound
 Sterile petrolactum contain gauze was used on top of the cpd
containing gauze to keep the wound humid
 The rabbits were sacrificed24 h after admin. of the cpds .
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11. OBSERVATION :
 Full thickness skin biopsy samples were taken from the center of
the burns sterility and homogenized in saline
 the homogenates were serially 10 fold diluted &0.1ml aliquots were
spread onto nutrient agar plates
 The plates were incubated at 35°c for 48h, and no. of viable
organism in the burn wounds were determined
EVALUATION
 Test cpds which reduce the viable colony counts is compared to
that of the control group
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12. MOUSE ASCENDING UTI MODEL
PRINCIPLE :
 The therapeutic efficacy of test drugs in mouse ascending UTI
caused by E.Coli bact.suspension was evaluated with female CD-11
CR mice. Test drugs exhibited a high degree of dose dependent
efficacy against bacterial suspension
REQUIREMENTS:
 Animal : CD-11CR mice ( 20-22g 10 mice /gp F)
 challenge dose, 2.2 x109 CFU/mouse
 Test cpds
 Anesthesia ; pentobarbital Na 0.05ml
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13.  Saline & test cpds were admin, SC at 6,24,30,48 & 54h post
infection.
 Mice were sacrificed 72 h after infection
 PROCEDURE :
 Female mice of 20-220gm body weight were selected randomly and
grouped into 10mice /gp
 5 diff.doses of tests were used
 The mice were subjected to water restriction for 24 hrs prior to &
after infection
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14.  Under anesthesia a round point needle was inserted trans urethrally
for inj.0.05ml of the bacterial suspension in 5% mucin into the
bladder
 Urethral needle was removed immediately after inoculation &
external urethral meatus clamped for 1 h
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OBSERVATION:
 Kidneys were removed and homogenized in saline , the
homogenates serially diluted 10-fold diluted , & 0.1 ml aliquots were
spread onto agar plates
 Plates were incubated at 35◦c for 48h & no. of viable organism in
the kidney (CFU/ gm) were determined
EVALUATION
 Test cpds which reduce no. of viable organism in the kidney is
compared to that of the control group

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