Gram-negative, facultatively anaerobic, rod-shaped, non-spore-forming bacteria of the family Enterobacteriaceae. Also oxidase-negative, indole-negative, and urease-negative. The genus Enterobacter ferments lactose with gas production during a 48-hour incubation at 35-37°C in the presence of bile salts and detergents.
Several strains of these bacteria are pathogenic and cause opportunistic infections in immunocompromised (usually hospitalized) hosts and in those who are on mechanical ventilation.
The urinary and respiratory tracts are the most common sites of infection.
The genus Enterobacter is a member of the coliform group of bacteria. It does not belong to the fecal coliforms (or thermotolerant coliforms) group of bacteria, as does Escherichia coli, because it is incapable of growth at 44.5°C in the presence of bile salts.
Two clinically important species from this genus are
E. aerogenes and
Important considerations: The choice of an agent should be based on local antimicrobial sensitivities, site of infection, cost, and comorbid conditions. Generally, the most common agents/regimens are listed first.