Final proof is obtained by culture. Serologic tests are highly unreliable. Control Hygienic food processing and storage may reduce the risk of listeriosis. Even an attenuated living vaccine is dangerous for persons with impaired defenses, the proper target group. Completely avirulent live bacteria do not trigger an effective, cell-mediated immune response.
Antimicrobial agents are the mainstay of treatment.
Most of the common antibiotics, except cephalosporins, are active against L monocytogenes in vitro. In practice, ampicillin combined with an aminoglycoside has given the best results. However, because infection occurs mainly in infirm patients and because intracellular bacteria are hardly accessible to most drugs, the cure rate is low. Furthermore, Listeria cells, although inhibited, are not killed by ampicillin. High doses for prolonged periods are indicated.