This document describes three models used to screen for antibacterial activity: 1) The mouse systemic infection model tests compounds against infections caused by E. coli, Klebsiella pneumoniae, and Staphylococcus aureus in mice. One study showed broad-spectrum activity against gram-negative and gram-positive bacteria. 2) The rabbit skin burn infection model assesses compounds' ability to reduce viable E. coli colony counts in burn wounds created on rabbits. 3) The mouse ascending urinary tract infection model evaluates compounds' dose-dependent efficacy against an E. coli bladder infection in mice. Kidneys are examined for reductions in viable bacterial counts compared to controls.

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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