Page 18 - MNU microbiology theoritical 2025

General Microbiology & Immunology (PM 401) Second level Semester 4 2024/2025

2) Bacterial shapes

Shape Description

Coccus spherical
(pl. Cocci):

Bacillus rod shape
(pl. Bacilli)

Cocco-bacilli elongated cocci

Vibrio • A short, curved rod (eg, Vibrio cholera)
(plural: vibrios)

Spirillum • a curved rod long enough to form spirals (eg,
(pl: spirilla) Helicobacter pylori)

Spirochetes a long, helical cell with a flexible cell wall

Filamentous bacteria elongated to form filaments (Actinobacteria).

Pleomorphic • (pleo meaning “many” and morphic referring to
shape).
Bacteria that characteristically vary in their
shape

General Microbiology & Immunology (PM 401) theoretical handbook Page 7