What are Citrobacter?
Citrobacter spp. belong to the genus of gram-negative, anaerobic rod-shaped bacteria, which come from the family of enterobacteriaceae. The bacteria can grow through citrate and play an increasingly important role in the development of nosocomial infections. This refers to diseases that patients acquire as a result of a medical procedure, for example in hospitals or nursing homes. Werkmann and Gillen described Citrobacter for the first time in 1932.
What are Citrobacter characterised by?
The cells of Citrobacter bacteria are mobile due to their flagella, i.e. flagella. As facultative anaerobic pathogens, Citrobacter use various organic compounds as their building material and energy source. They get their name from the fact that they are the only energy source that can grow exclusively with the anion of citric acid, the so-called citrate. Belonging to the genus Enterobacteriaceae, the oxidase test is negative and the catalase test positive. Citrobacter are found in almost every habitat . In addition to soil, the bacteria can also be found in water, sewage, but also in the human gastrointestinal tract of the human intestinal flora.
Which species of Citrobacter are distinguished?
Citrobacter belong to the enterobacteria, which are composed of a large group of gram-negative bacteria. These include the following genera, some of which play a role in the development of diseases:
- Enterobacter,
- Escherichia,
- Klebsiella,
- Proteus mirabilis,
- Raoultella,
- Salmonella,
- Serratia,
- Shigella,
- Yersinia
The following species of Citrobacter are distinguished, among others:
- Citrobacter amalonaticus,
- Citrobacter braakii,
- Citrobacter farmeri,
- Citrobacter freundii,
- Citrobacter gillenii,
- Citrobacter koseri,
- Citrobacter murliniae,
- Citrobacter rodentium,
- Citrobacter sedlakii,
- Citrobacter werkmanii,
- Citrobacter youngae
In humans, especially Citrobacter freundii, Citrobacter koseri and Citrobacter braakii can cause severe infections.
Which infections can be caused by Citrobacter?
Citrobacter bacteria occur in the normal intestinal flora of humans and are usually not pathogenic, i.e. pathogenic. In some cases, however, the bacteria can trigger urinary tract infections, blood poisoning (sepsis), but also wound infections and infections of the respiratory tract and thus appear as extraintestinal infections, i.e. diseases outside the intestine. Patients with a weakened immune system in particular tend to become ill with Citrobacter bacteria . But Citrobacter also play an increasingly important role in the development of the so-called hospital infections (nosocomial infections). In exceptional cases, Citrobacter bacteria can cause meningitis and/or sepsis in infants.
What are the symptoms of Citrobacter infections?
- Citrobacter infections of the skin can resemble those of osteomyelitis and cause redness, swelling, but also localised pain and/or pus ,
- Citrobacter infections leading to pneumonia are characterised by high fever, difficulty breathing, cough with or without sputum, a general feeling of weakness (asthenia) and a deterioration of the general condition,
- Citrobacter infections that lead to urinary tract infections are characterised by pain when urinating (stranguria), a frequent urge to urinate (pollakiuria), pain in the pelvic and/or lumbar region, purulent urine and/or blood in the urine (haematuria), fever,
- Citrobacter infections causing sepsis are characterised by fever over 38 °C, pain in the limbs, general malaise, chills and/or confusion . If the sepsis worsens, there may also be a drop in blood pressure.
- Citrobacter infections, which are caused by C. koseri, often cause meningitis, especially in newborns , which is often accompanied by necrotising encephalitis (an inflammation of the entire brain tissue, or parts of it) and/or brain abscesses.
How is a Citrobacter infection diagnosed?
If a Citrobacter infection is suspected, various analyses are carried out to diagnose the bacterium in the body . In addition to a skin swab, these diagnostic methods include a urine analysis or urine culture as well as a blood test, blood cultures and a sputum examination. Biochemical and/or molecular tests can confirm the diagnosis of a Citrobacter infection.
How are Citrobacter infections treated?
The following medications may be prescribed for infections with Citrobacter bacteria:
- Cefotaxime and Ceftriaxom or Ciprofloxacin and Levofloxacin, which are particularly effective for Citrobacter koseri bacteria,
- Aminoglycosides, quinolones, ertapenem, imipenem or meropenem, which are used in the treatment of Citrobacter freundii pathogens.
Since the Citrobacter bacteria can develop resistance to penicillins and various combinations of ?-lactam antibiotics, it is important to carry out a sensitivity test before treatment. Currently, there are several bacterial strains that show antibiotic resistance (multiresistance). For these, the drug colistin is the only effective active ingredient so far. Colistin is only available on prescription and requires the general condition of the patient to be checked by the doctor in order to prevent the occurrence of possible toxic effects during treatment.
How can I get infected with Citrobacter bacteria?
Transmission with Citrobacter usually occurs through direct or indirect contact with contaminated objects or persons. In hospitals, this happens through contact with medical staff, for example, via the hands if they have not been disinfected correctly . But infection is also possible via diagnostic tools or ordinary objects or surfaces. The mother can also infect the child during the birth process. But infection is also possible through contaminated food.
How can you protect yourself from a Citrobacter infection?
In order to at least avoid the transmission of Citrobacter bacteria in hospital, the following should be observed:
- strictly adhere to preventive measures to avoid infection, for example through the correct use of disinfectants, thorough hand washing, and the cleaning of the environment,
- quickly recognise a possible infection and control its outbreak,
- treat a possible infection quickly through the correct use of antibiotics,