- Microscopic appearance

- Cultural characteristics

- Biochemical Tests of Campylobacter species.

Campylobacter

Campylobacters are

small delicate,

spirally curved,

motile Gram

negative bacteria

Campylobacters jejuni

Campylobacters coli

Campylobacter jejuni causing:-

- Enteritis.

*** Fresh diarrhoeal or dysenteric specimens

containing blood, pus and mucus (child under

2 y).

Campylobacters are Gram negative curved rod

A filtration technique and a non-selective culture

medium. A filter of 0.47 μm pore size will retain

faecal commensals and allow Campylobacters to

pass through

A selective culture medium that contains

antimicrobials to inhibit the growth of faecal

commensals.

Blaser’s medium: Containing 10% sheep blood, vancomycin,

trimethoprim, polymyxin B, cephalothin, amphotericin B.

Skirrow’s blood agar: Containing lyzed horse blood, vancomycin,

polymyxin B, trimethoprim

Butzler virion medium: Containing defibrinated sheep blood, cefoperazone, rifampicin, colistin, amphotericin B.

Improved Preston blood free-medium: Containing

cefoperazone

and amphotericin B. This supplement is added to a

Campylobacter blood-free agar base containing

bacteriological charcoal, ferrous sulphate, sodium

deoxycholate, sodium pyruvate, casein hydrolysate,

nutrient broth and agar. Isolations are best on this medium

when cultures are incubated at 37 ºC rather than 42–43 ºC

C. jejuni produces grey,

moist, flat-spreading

colonies. Some strains

may have a green hue or a

dry appearance with or

without a metallic sheen.

On Blood agar: C. jejuni and C. coli produce

nonhaemolytic spreading, droplet-like colonies

Catalase Test

Oxidase Test

-Hippurate hydrolysis: this test can be used to differentiate

C. jejuni from C. coli.

-Hippurate is hydrolyzed by C. jejuni and not hydrolyzed by

C. coli.

The end product of hydrolysis of hippuric acid by

hippuricase include glycine and benzoic acid.

Glycine is deaminated by the oxidizing agent

ninhydrin.

The end products of the ninhydrin oxidation reacts

to form a purple-coloured product.

- Microscopic appearance

- Cultural characteristics

- Biochemical Tests of Helicobacter species.

Helicobacter

Helicobacter

- gastric and duodenal ulcers (eradication of H. pylori

results in cure and reduces ulcer recurrence in 90% of

peptic ulcer patients).

- H. pylori also contribute to diarrhoea, malnutrition and

growth failure in young children (reduced gastric acid

protection leads to infection with enteropathogens).

- To isolate H. pylori by culture a gastric biopsy is

required. Place a biopsy of mucosa from the gastric

antrum in a bottle containing about 0.5 ml of sterile

physiological saline.

It should reach the laboratory with the minimum of delay.

Using a sterile scalpel and forceps,

cut the biopsy into small pieces.

Inoculate a plate of chocolate

(heated blood) agar or

Campylobacter medium, and

also place a piece of biopsy in

Christensens urea broth

H. pylori appears as a small, spiral or S-shaped Gram

negative bacterium

On blood agar, H. pylori colonies are slightly

beta-haemolytic. Growth is best at 37 ºC

When the strain is urease producing, the enzyme will break down

the urea (by hydrolysis) to give ammonia and carbon dioxide.

With the release of ammonia, the medium becomes alkaline as

shown by a change

in colour of the indicator to pink-red.

Urease Test

The test organism is

cultured in a medium which

contains urea and the

indicator phenol red.

Urea breath test