Gram Stains of Anaerobic Bacteria

Diptheroids

There are aerobic and anaerobic species of diptheroids. Note the Chinese letter / picket fence formation which is very typical of diptheroids

Lactobacillus sp.

This organism is a large gram positive rod and can form long chains.

Bacteroides Fragilis

This anaerobe is a small pleomorphic Gram negative rod. In the upper right hand corner is E. coli and Enterococcus faecalis for size comparison.

Bacteroides Fragilis and
Peptostreptococcus Anaerobius

Clostridium perfringens @ about 24 hours

This anaerobe is described as a large gram positive rod with a "box car" shape with square ends.

Clostridium perfringens @ about 48 hours

As this organism gets older, it looses its ability to hold the crystal violet in the peptidoglycan layer and therefore, becomes Gram variable.

Clostridium perfringens older than 72 hours

Notice spotty uptake of the crystal violet in these cells taken from a very old colony.

Fusobacterium Nucleatum

This species of Fusobacterium has a long thin tapered rod shape.

Peptostreptococcus anaerobius

Note the chains, which resemble streptococcus spp.

Viellonella Parvula

Note the very small gram negative cocci

Proprionibacterium Acnes

Note the diphtheroid arrangement (Chinese letter / palisade formation)