Citrobacter

Citrobacter freundii

Citrobacter is a genus of Gram-negative bacteria belonging to the family Enterobacteriaceae. The bacteria are named after the citrus fruit where they were first isolated. Citrobacter species are facultatively anaerobic and are characterized by their ability to ferment lactose with the production of gas in a 48-hour period at 37°C. They are commonly found in soil, water, and the intestinal tracts of animals and humans. Among the various species, Citrobacter freundii is the most well-known, often associated with opportunistic infections in humans.

Characteristics

Citrobacter species are rod-shaped and can be distinguished from other members of the Enterobacteriaceae family by their biochemical characteristics. They are capable of utilizing citrate as a carbon source and produce hydrogen sulfide. These bacteria also vary in their ability to convert tryptophan to indole, with some species being positive and others negative for this trait.

Pathogenicity

While Citrobacter is commonly found in the environment and is usually harmless, it can cause infections in humans, especially in those with weakened immune systems. Infections can range from urinary tract infections, respiratory infections, and, in rare cases, meningitis, particularly in neonates. The treatment of Citrobacter infections can be complicated due to the bacteria's resistance to multiple antibiotics.

Epidemiology

Citrobacter species have been isolated from a variety of environments, including water, soil, and the gastrointestinal tract of animals and humans. They can be transmitted to humans through the consumption of contaminated water or food, or through direct contact with contaminated surfaces. In healthcare settings, Citrobacter can cause nosocomial infections.

Clinical Significance

The clinical significance of Citrobacter infections lies in their potential to cause disease in susceptible individuals and the challenges in treating these infections due to antibiotic resistance. It is important for healthcare providers to identify Citrobacter infections promptly and to choose appropriate antibiotic therapy based on susceptibility testing.

Prevention and Control

Prevention of Citrobacter infections involves general hygiene measures, such as regular handwashing, especially in healthcare settings. In hospitals, strict infection control measures are necessary to prevent the spread of these bacteria among patients.