Shigella Flexneri

WHAT IS IT?

Shigella flexneri is a gram negative rod (bacilli) enteric bacterium. 

CULTURE CHARACTERISTICS

Non -lactose fermeting 

Oxidase negative

Negative for H2S production on TSI agar 

MOLECULAR CHARACTERISTICS

Type II secretion system (“injectosome”): needle like appendage that facilities the direct delivery of toxins to eukaryotic host cell. 

Shigella toxin: inactivates 60S ribosome by removing adenine from rRNA. Inhibits protein synthesis and causes cell death. 

TRANSMISSION

Fecal-oral transmission 

Human reservoir only

CONDITIONS CAUSED

Shigellosis: causes GI mucosal damage that leads to dysentery. 

Hemolytic Uremic Syndrome (HUS): the shigella toxin enhances cytokine release, resulting in HUS. 

Reactive arthritis

TREATMENT

Penicillinase-sensitive penicillins: Amoxicillin, ampicillin; aminopenicillins 

Trimethoprim-sulfamethoxazole

First generation (quinolone): Nalidixic acid 

OTHER HY FACTS

As few as 10 Shigella organisms can cause disease (depending on the age and condition of the host). 

 

Page Updated: 04.06.2017