Staphylococcosis in poultry: Symptoms, Causes and Diagnosis

Staphylococcosis is caused by the bacterium Staphylococcus aureus. S. aureus infections are common in poultry. A wide variety of conditions are associated with the disease-producing strains of S. aureus.

Among these the important conditions are yolk sac infection, gangrenous dermatitis, bumble foot, and staphylococcal septicaemia (i.e., blood infection). S. aureus produces a number of toxins and enzymes which influence its disease-producing power.

Spread

I. For infection to occur, injury to the skin or mucous membranes is essential. S aureus enters

through the broken barriers and travels to internal locations, where a focus of infection is established.

2. In newly hatched chicks, the open navel provides a route of entry leading to omphalitis (inflammation of

navel) and other types of infection.

Disease

I. Yolk sac Infection

See 'yolk sac infection' under 'coli bacillosis' (see also Figs. 46, 47, 48, 49, 50).

2. Gangrenous Dermatitis

This occurs in birds of all ages, but is most common in broilers, and in growers between 15 to 20 weeks of

age. The wing tips and the dorsal pelvic region are the sites affected. The affected sites are dark, moist, and

gangrenous (decaying) in appearance (see Fig. 70, 71, 72, 73) with a crackling sound. Staphylococci are usually

associated with Clostridium perfringens, which may be the main disease-producing organism.

3. Bumble Foot

Bumble foot is an abscess in the foot pad (see 'bumble foot'). It usually occurs in mature birds. The abscess

formation is accompanied by swelling, heat, and usually some pain. This leads to lameness. The undersurface

of the foot is first affected, and the lesion may then spread to invade the whole foot (Fig. 144, 145).

4. Staphylococcal Septicaemia (Blood Infection)

Staphylococcal infection is the invasion of the blood by staphylococci. It usually occurs from a local seat of

infection. It is relatively rare and may result in sudden death.

Symptoms

Early symptoms include ruffled feathers, limping on one leg, hanging downwards of one or both wings, and

fever. This may be followed by severe depression and death.

Postmortem Findings

Postmortem findings of yolk sac infection, gangrenous dermatitis and bumble foot have been described under

their descriptions at other places. Postmortem findings in case of staphylococcal septicaemia include

appearance of multiple foci of necrosis (white spots of dead tissue) in the liver (Fig. 80), lungs, kidneys, spleen,and heart.

Diagnosis

The history, symptoms, if any, and postmortem findings may be helpful, but it is necessary to isolate and identify

S. aureus to confirm diagnosis.

Treatment

s. aureus infection can be successfully treated, but sensitivity tests should always be performed because antibiotic

resistance is common. Drugs used successfully for treatment include penicillin, tetracycline, streptomycin,

erythromycin, lincomycin, and sulphonamides.

Control

I. Because wounds are a route of entry for S. aureus into the body, anything reducing the chances of injury

will help prevent infection.

2. Maintenance of good litter quality will reduce foot pad ulceration.

Fig.