The infectious agents incriminated in the event of a bite and scratch are those of the oral cavity and those of the skin (Pasteurella, Bartonella, Staphylococcus, Streptococcus spp, Capnocytophaga canimorsus and anaerobic bacteria).
cat scratch disease
Due to Bartonella henselaean intracellular Gram-negative bacterium, the disease is responsible for lesions vesicular or papular erythematous skin (3-10 days of incubation), followed by lymphadenopathy in the drainage area which may progress to suppuration (fig. 2). infective endocarditis B. henselae preferentially occurs on pre-existing valvular disease and requires serology and transthoracic echocardiography.
Pasteurellosis
It is due to Pasteurella multilocida (gram-negative bacteria). The incubation is very short (3 to 24 hours). The inoculation lesion is inflammatory (fig. 1) with purulent discharge, and may be accompanied by satellite lymphadenopathy and sometimes lymphangitis. In the absence of treatment, arthritis, osteomyelitis, tendinopathy, and more rarely sepsis and secondary locations (pneumopathy, meningitis, endocarditis) may occur.
infection Capnocytophaga canimorsus
It can cause severe complications in humans such as endocarditis, sepsis, septic shock, and even death, particularly in asplenic, immunocompromised or chronic liver disease patients.
infection Streptobacillus moniliformis
Although scratches and bites from rats, mice or other rodents remain anecdotal, 10% of them may be complicated by this infection (incubation of 4 to 10 days) which is manifested by a febrile rash, sepsis, secondary localizations (arthritis, abscess, pneumopathy, meningitis, endocarditis) and rarely death.
snake bite
A snakebite can become infected with the animal’s oral flora (probably of a fecal nature, due to the droppings of their prey): Pseudomonas aeruginosa, Proteus sp, Clostridium sp, Bacteroides fragilis, Salmonella sp.
In addition to the risk of infection, there may be a risk of envenomation (in France, only vipers and Montpellier snakes have venom fangs). To limit the spread of venom : immobilize the person, place it so that the bitten part is located lower than the level of the heart (never apply a tourniquet; no need to suck the venom). It is necessary to reassure the patient, calm him down and above all avoid useless or even dangerous gestures (tourniquet, ingestion of alcohol, systematic injection of polyvalent antivenom serum, administration of corticosteroids or subcutaneous heparin) and call 15 (assessment and administration in hospital care).
Rage
In mainland France, it has become a disease essentially of travelers exposed to rabies enzootic zones, the risk of human exposure to a terrestrial mammal is low (a few illegally introduced animals). Nevertheless, rabies must be taken into account especially in case of bat bite (absolute indication for immediate post-exposure prophylaxis combining specific immunoglobulins and anti-rabies treatment); if the bite comes from an unknown animal, contact the anti-rabies centre.
