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Chapter 8.5 : Examination and Evaluation of Primary Cultures

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Abstract:

Primary plates are read daily for the first week, every other day for the second week, and twice weekly for the remaining 2 weeks. The use of 4 weeks of incubation has been challenged by some groups because few new positive cultures develop in the fourth week. I have noted that clinically significant positive cultures are sometimes seen in the fourth week, suggesting the need to retain this incubation period. In areas of endemicity of systemic dimorphic pathogens, incubation for 5 weeks should be considered, as occasional isolates of and may require that much time to form evident colonies. In cases of eumycetoma, the etiologic agent may not be evident on culture until the fifth or sixth week. When growth appears, differentiate between yeast and filamentous forms (moulds) that may require microscopic examination. Use wet mounts or stain with lactophenol cotton blue (LPCB) (item V.B below). If the isolate suggests an actinomycete, examine with Gram stain and with a modified acid-fast stain. (Procedures for the identification of aerobic actinomycetes are given in procedure 6.1, items V.D.1 and V.D.2.)

Citation: Garcia L. 2010. Examination and Evaluation of Primary Cultures, p 415-424. In Clinical Microbiology Procedures Handbook, 3rd Edition. ASM Press, Washington, DC. doi: 10.1128/9781555817435.ch8.5
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Figures

Image of Figure 8.5–1a
Figure 8.5–1a

Flowchart for evaluating a possible yeast species on primary culture. (A) Identification procedure when yeast cells are found in brain abscess or CSF specimen. See Fig. 8.3–1 for common yeast agents isolated from different body sites. (B) Identification procedure for yeasts when the specimen is not brain abscess or CSF.

Citation: Garcia L. 2010. Examination and Evaluation of Primary Cultures, p 415-424. In Clinical Microbiology Procedures Handbook, 3rd Edition. ASM Press, Washington, DC. doi: 10.1128/9781555817435.ch8.5
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Image of Figure 8.5–1b
Figure 8.5–1b

Flowchart for evaluating a possible yeast species on primary culture. (A) Identification procedure when yeast cells are found in brain abscess or CSF specimen. See Fig. 8.3–1 for common yeast agents isolated from different body sites. (B) Identification procedure for yeasts when the specimen is not brain abscess or CSF.

Citation: Garcia L. 2010. Examination and Evaluation of Primary Cultures, p 415-424. In Clinical Microbiology Procedures Handbook, 3rd Edition. ASM Press, Washington, DC. doi: 10.1128/9781555817435.ch8.5
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Download as Powerpoint
Image of Figure 8.5–2a
Figure 8.5–2a

Simple tests to determine genera of yeast cells seen on primary culture. (A and B) Identification procedures when colony color is white, cream, or tan. (C) Identification procedure when colony color is salmon, pink, or red. (D) Identification procedure when colony color is brown or black.

Citation: Garcia L. 2010. Examination and Evaluation of Primary Cultures, p 415-424. In Clinical Microbiology Procedures Handbook, 3rd Edition. ASM Press, Washington, DC. doi: 10.1128/9781555817435.ch8.5
Permissions and Reprints Request Permissions
Download as Powerpoint
Image of Figure 8.5–2b
Figure 8.5–2b

Simple tests to determine genera of yeast cells seen on primary culture. (A and B) Identification procedures when colony color is white, cream, or tan. (C) Identification procedure when colony color is salmon, pink, or red. (D) Identification procedure when colony color is brown or black.

Citation: Garcia L. 2010. Examination and Evaluation of Primary Cultures, p 415-424. In Clinical Microbiology Procedures Handbook, 3rd Edition. ASM Press, Washington, DC. doi: 10.1128/9781555817435.ch8.5
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Download as Powerpoint
Image of Figure 8.5–2c
Figure 8.5–2c

Simple tests to determine genera of yeast cells seen on primary culture. (A and B) Identification procedures when colony color is white, cream, or tan. (C) Identification procedure when colony color is salmon, pink, or red. (D) Identification procedure when colony color is brown or black.

Citation: Garcia L. 2010. Examination and Evaluation of Primary Cultures, p 415-424. In Clinical Microbiology Procedures Handbook, 3rd Edition. ASM Press, Washington, DC. doi: 10.1128/9781555817435.ch8.5
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Download as Powerpoint

References

/content/book/10.1128/9781555817435.chap8.5
1. Odds, F. C.,, and R. Bernaerts. 1994. CHROMagar Candida, a new differential isolation medium for presumptive identification of clinically important Candida species. J.Clin.Microbiol. 32:19231929.
2. Freydiere, A.-M.,, R. Guinet,, and P. Boiron. 2001. Yeast identification in the clinical laboratory: phenotypic methods. Med.Mycol.39:933.
3. Haley, L. 1978. Laboratory Methods in Medical Mycology. U.S. Department of Health, Education, and Welfare, CDC publication no. 78-8361, p. 94. U.S. Department of Health, Education, and Welfare, Washington, DC.
4. Haley, L. D.,, and C. S. Callaway. 1978. Laboratory Methods in Medical Mycology. U.S. Department of Health, Education, and Welfare, CDC publication no. 78-8361, p. 30. U.S. Department of Health, Education, and Welfare, Washington, DC.

Tables

Generic image for table
Table 8.5–1

General list of yeast species or genera based on colony color.

Based on growth on Sabouraud glucose agar (Emmon's modification), potato dextrose agar, malt extract agar, or BHI agar. Note that all spp. except require exogenously supplied lipid (e.g., olive oil) for growth.

Previously Exophiala werneckii.

A second anamorphic (asexual) form (i.e., synanamorph) of

Not a yeast but produces yeastlike colonies on mycological media.

Sexual genera associated with some species of the anamorphic genera.

Citation: Garcia L. 2010. Examination and Evaluation of Primary Cultures, p 415-424. In Clinical Microbiology Procedures Handbook, 3rd Edition. ASM Press, Washington, DC. doi: 10.1128/9781555817435.ch8.5
Generic image for table
Table 8.5–2

Summary of subsequent tests

These tests are described in procedures 8.6 and 8.7.

Citation: Garcia L. 2010. Examination and Evaluation of Primary Cultures, p 415-424. In Clinical Microbiology Procedures Handbook, 3rd Edition. ASM Press, Washington, DC. doi: 10.1128/9781555817435.ch8.5

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