VPM 201: Veterinary Bacteriology and Mycology
Laboratory 2: Staphylococcus and Streptococcus
Day 1 (Laboratory 2A)
A. Laboratory Exercises
Sample 1. A dog presents with pyoderma of the face and limbs. Material from pustules was
plated on BA and MAC and incubated overnight at 37 ºC. There was no growth on MAC.
(S. pseudintermedius)
a. Observe the culture for hemolysis and record observations.
b. Perform gram staining and record microscopic results. Is it gram + or -? Cocci or rod?
c. Perform a catalase test. Is it positive (bubble-forming) or negative?
d. Is it coagulase positive? (see Demo 2).
Sample 2. Cultures growing on BA are from an acute exudative dermatitis in a recently weaned
pig. The plates were incubated at 37 ºC for 24 hrs. There was no growth on MAC (S. hyicus).
a. Observe hemolysis and record observations.
b. Perform gram staining. Is it gram + or -? Cocci or rod?
c. Perform a catalase test. Can you see bubbles?
d. Is it coagulase positive? (see Demo 2).
Now you have the test results. Please identify samples 1 and 2 based on the disease conditions,
the cocci flow chart (lab handout page 3), and the table below.
Test
S. aureus
Catalase
Complete hemolysis
Coagulation
+
+
+ (fast)
S. intermedius
group
+
+
+ (slow)
1
S. hyicus
+
var
B. Demonstration Materials
1. Bacterial cultures on BA plates: S. aureus, S. intermedius, S. pseudintermedius, S. hyicus
2. Coagulase tests
a. sample 1 & sample 2
b. + ve & - ve (tube and slide)
Day 2 (Laboratory 2B)
A. Laboratory Exercises
Sample 1: This organism was isolated from a 2-year old horse with a nasal discharge and fever.
The horse had difficulty in breathing and swallowing. The organism did not grow on MAC. (S.
equi)
a. Observe the BA culture for hemolysis.
b. Perform gram staining. Is it gram + or -? Cocci or rod?
c. Perform a catalase test. Can you see bubbles?
d. Based on the disease conditions, the cocci flow chart (lab handout page 3) and the test results,
can you i.d. the organism?
Sample 2: The culture on BA is from a Holstein with acute mastitis. The organism did not grow
on MAC. Please perform the following tests. (S. dysgalactiae)
a. Observe the culture for hemolysis.
b. Perform gram staining and record your microscopic observation.
c. Perform a catalase test.
d. See the CAMP test (Demo 2). Is the hemolysis augmented? What is your presumptive i.d. of
the organism?
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B. Demonstration materials
1. Cultures: S. agalactiae, S. dysagalactiae, S. equi, S. suis, Enterococcus faecalis
2. CAMP test
a. Sample 2
b. S. agalactiae and S. dysgalactiae
C. Questions
1. How can you distinguish Staphylococcus and Streptococcus based on a catatase test?
2. You observed gram-staining of Staphylococcus and Streptococcus with microscope. Can you
tell their differences?
3. Which one showed augmented hemolysis with S. aureus between S. agalactiae and S.
dysgalactiae?
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