Procedures and Biochemical Identification of Bacteria

Catalase, an enzyme that produces water and oxygen from hydrogen peroxide

• POS - Staphlococcus
• NEG - Streptococcus

• POS - Staph aureus (also S. intermedius and S. hyicus)
• More specific agglutination tests are now performed

Detects the enzyme L-pyrrolidonyl arylamidase

• NEG - Staph aureus
• POS - S. lugdensis, S. schleiferi, Strep pyogenes (Group A), and Enterococcus species

• Strep pneumoniae
• In the presence of bile at 37 degrees celcius, colonies will autolyse within 30 min and disappear from the agar surface

Detects the bacterial enzyme hipuricase - which hydrolyzes hippurate to glycine and benzoic acid

• POS - Group B Strep, Campylobacter jejuni
• NEG - Most other beta-hemolytic Streps, Campylobacter species

Detects chytochrome oxidase that is used in the electron transport system

POS - Pseudomonas species, Neisseria gonorrheae

Detects the bacterial enzyme tryptophanase (tryptophan is broken down by tryptophanase into pyruvic acid, ammonia, and indole)

Urease breaks down urea to form ammonia (NH₃)

TSI will show the pattern of glucose, lactose, and sucrose fermentation in addition to H2S and gas production

• Alkaline slant/alkaline deep (K/K) - Nonfermentor, NOT Enterobacteriaceae
• Alkaline slant/acid deep (K/A) - Nonlactose and nonsucrose fermenter, glucose fermenter
• Acid slant/acid deep (A/A) - Lactose and/or sucrose fermenter, and glucose fermenter
• Black deep, production of H₂S gas - production of hydrogen sulfide (H2S) from sulfer-containing molecules in the medium
• Lead acetate - added to filter paper strips and one end is held in place by the cap.  If H₂S gas is produced, a black color will form

• Nonfermentor
• NOT Enterobacteriaceae

• Nonlactose and/or Nonsucrose fermenter
• Glucose fermenter

• Lactose and/or sucrose fermenter
• Glucose fermenter

• pH indicator
• Yellow at acid pH (indicating glucose fermentation)
• Red is NEG

• Detects the metabolism of glucose to acetyl-methyl-carbinol (acetoin)
• Bacteria are usually MR or VP POS

Determines if citrate is used as a sole carbon source

• Detects the presence of beta-galactosidase, an enzyme that cleaves ONPG and lactose
• Test is useful in detecting delayed (late) lactose fermenters that lack or are deficient in beta-galactoside permease

Detects bacterial enzymes that break down various amino acids

Detects the ability of an organism to remove the amino group from specific amino acids

Detects the ability of bacteria to remove the carboxyl group from a specific amino acid

• Deaminase reaction
• Decarboxylation reaction

• Tryptophan (tryptophan deaminase)
• Lysine (lysine decarboxylase)
• Ornithine (ornithine dihydrolase)

Detects the ability of bacteria to produce organic acids by the fermentation of various carbs

Determines the ability of an organism to reduce nitrate (NO₃) to nitrite (NO₂) and nitrogen gas (N₂)

The fatty acid composition of the bacterial cell wall as determined by gas chromatography

• The fatty acids in mycobacteria have a larger molecular weight
• Identified via high-performance liquid chromatography in the Sherlock Mycobacteria Identification System

• Gram Crystal Violet
• Gram Iodine
• Acetone-Alcohol Decolorizer
• Safranin Counterstain

• Catalase POS
• Glucose fermentation NEG
• Bacitracin SENSITIVE
• Modified Oxidase POS

Haemophilus parainfluenzae

Haemophilus influenzae

Pseudomonas

• Salmonella
• Proteus
• Citrobacter

• Proteus
• K. pneumo
• Providencia
• Morganella

Shigella

• Clostridium perfringens
• (Reverse CAMP test)

• Positive for Group B beta Strep
• (Positive CAMP test)