Growth at 42°C Test- Principle, Procedure and Result Interpretation
Purpose of Growth at 42°C Test
This test is used to differentiate a pyocyanogenic pseudomonads from other Pseudomonas sp.
Principle of Growth at 42°C Test
The test is used to determine the ability of an organism to grow at 42°C. Several Pseudomonas species have been isolated in the clinical laboratory that are capable of growth at elevated temperatures.
Procedure of Growth at 42°C Test
- Inoculate two tubes of trypticase soy agar (TSA) with a light inoculum by lightly touching a needle to the top of a single 13- to 24-hour-old colony and streaking the slant.
- Immediately incubate one tube at 35°C and one at 42°C.
- Record the presence of growth on each slant after 18 to 24 hours.
Result Interpretation of Growth at 42°C Test
Positive: Good growth at both 35°and 42°C.
Negative: No growth at 42°C, but good growth at 35°C.
Positive: Pseudomonas aeruginosa (ATCC10145)
Negative: Pseudomonas fluorescens (ATCC13525)