Spiral bacterium – Spirillum spp.

The term spirilla was originally used to describe spiral, cork screw organisms regardless of whether they were vibrios, spirilla or spirochaetes.

Spirillum is microbiologically characterized as a gram-negative, motile helical cell with tufts of whiplike flagella at each end. The helix of the largest spirillum, S. volutans, is 5 to 8 μm (micrometres; 1 μm = 10-6 metre) across by 60 μm long.

Spirilla possess a strictly respiratory metabolism, with oxygen as the terminal electron acceptor; they are oxidase- and catalase-positive, an usually phosphate-positive. Large clusters of flagella are present on each end of the cell to help with movement.

The difference between spirillum and spirochaete is that the former possesses a rigid, non-flexuous cell body, while the latter has a flexuous cell body and no true flagella.

Members of the genus Spirillum were probably first described in the 1670s by van Leeuwenhoek and a century later by Muller. The genus Spirillum was created in 1832 by Ehrenberg, and from his descriptions of members of the genus in 1838 it is clear that rigid helical cells were being described rather than flexible cells such as spirochetes.
Spiral bacterium – Spirillum spp.

Spirillum volutans

Campylobacter jejuni

Campylobacter jejuni Campylobacter jejuni is considered to be a pathogen principally of veterinary significance only slightly more than decade ago, Campylobacter jejuni (formerly known as Vibrio fetus) was known to cause abortion in sheep. 

Following the development of procedures for detecting the organism in stool specimens, Campylobacter jejuni became recognized as a leading cause of acute bacterial gastroenteritis in humans. 

Campylobacter jejuni is a gram-negative, microaerophilic, thermophilic rod that grows best at 42°C (107°F) and low oxygen concentrations. 

These characteristics are adaptations for growth in its normal habitat – the intestines of warm-blooded birds and mammals. 

Several closely related species with similar characteristics, C. coli, C. fetus, and C. upsalienis, may also cause disease in man but are responsible for less than one percent of human infections annually. Evidence suggests that Campylobacter is responsible for at least as many cases of enteric illness as Salmonella. 

Indeed, it is now believed that campylobacteriosis is more common in the United States than salmonellosis and shigellosis combined. Common symptoms of campylobacter enteritis include profuse diarrhea (sometimes containing blood), abdominal cramps and nausea. 

Human volunteer and retrospective studies of food associated outbreaks revealed that ingesting relatively small numbers (only a few hundreds cells) of Campylobacter jejuni can produce illness. 

Campylobacter jejuni