Anaerobes can be overgrown by more rapidly growing facultative organisms. Examine and Gram stain broth if plating medium
reveals no growth. Never rely on broth cultures exclusively for isolation of anaerobes. Some anaerobes may be inhibited by
metabolic products or acids produced from more rapidly growing facultative anaerobes.
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Culture media sometimes contain dead organisms derived from medium constituents, which may be visible in smears of culture
media. Other sources of dead organisms visible upon Gram staining include staining reagents, immersion oil, glass slides and
the specimens used for inoculation. If there is uncertainty about the validity of the Gram stain, the culture should be
reincubated for another hour or two and the test repeated before a report is given.
For identification, organisms must be in pure culture. Morphological, biochemical, and/or serological tests should be performed
for final identification. Consult appropriate texts for detailed information and recommended procedures