Klebsiella is the name given to a group of bacteria that belong to the Gram-negative rod-shaped bacteria and thus to the Enterobacteriaceae family. Almost all subgenera of the bacterial species are completely harmless to a healthy person, but can cause severe infections in persons with immunological weakness. A major problem in this context is the multiresistance of the genus.
What are Klebsiella?
Klebsiella is a generic name for microorganisms. The genus is a bacterial genus that contains, in particular, gram-negative rod-shaped bacteria. These rod bacteria come from the relatively large family of Enterobacteria, which in the phylogenetic system belongs to the class Gammaproteobacteria and division Proteobacteria. The discovery of Klebsiella can be traced back to the German bacteriologist Klebs. He described the genus in the 19th century. Bacteria from the genus Klebsiella do not possess active motility. They lie in a capsule of mucus and live in oxic living conditions. Thus, they get along with oxygen and live aerobically. However, the presence of oxygen is not a condition of survival for them. Even in the absence of oxygen, the bacteria are viable. In this context, bacteriology speaks of facultative anaerobes. On the colonies of Klebsiella lies a smeary film. Meanwhile, bacteriology assumes about eight different subspecies of the bacterial genus.
Occurrence, distribution, and characteristics
Bacteria from the genus Klebsiella live predominantly in soil, on grain or in water. These bacteria are also found in the human body. The subspecies Klebsiella pneumoniae physiolgically inhabits the gastrointestinal tract of humans. The distribution of the bacterial genus is ubiquitous. That is, the bacteria are found virtually “everywhere.” By the characteristic ubiquitous, bacteriology refers primarily to bacteria that are ubiquitous in an organism or present in all living things. Klebsial bacteria process organic matter to obtain energy. For this reason, they are sometimes described as chemoorganotrophic. If oxygen is present in their habitat, their metabolism breaks down organic matter to water and carbon dioxide. If they live in an anaerobic environment, the Klebsiae carry out a special fermentation and in this way produce various acids, CO2 and alcohol-2,3-butanediol. Accordingly, in an oxic environment, they possess oxidative energy metabolism and oxidize organic matter. In other subgenera of Enterobacteriaceae, mixed acid fermentation corresponds to the anaerobic pathway of energy metabolism. This difference is therefore relevant for differentiating the Enterobacteriaceae subgenera and can be detected using the Voges-Proskauer test. According to recent studies, Klebsiaceae of the genus Klebsiella pneumoniae are mainly found in meat from factory farming. Presumably, the bacteria can be transmitted to humans when such meat is consumed. However, such transmission has not yet been proven. Klebsiella are also widespread as hospital germs. The Robert Koch Institute investigated the outbreak in 72 hospital cases and was unable to determine the source of the germs. The researchers suspect that the bacteria are passed from person to person. For the human body, a particular subgenus of Klebsiella plays a role: Klebsiellen pneumoniae. These bacteria are found in the intestinal flora of a healthy person and are relatively harmless when the immune system is normal. However, although they are a component of the intestinal flora, they can cause disease in patients with lowered immune systems.
Diseases and ailments
Immunodeficient patients include AIDS sufferers, for whom the bacteria can be devastating. Although most subgenera of Klebsiella are harmless to humans, some subgenera still cause,
cause various infections in individuals with immunodeficiency. These infections include, for example, pneumonia, which corresponds to inflammation of lung tissue. Klebsiella can also cause urinary tract infections, such as chronic forms of cystitis. Since the bacteria colonize the gastrointestinal tract, they can also cause diarrhea in immunodeficient patients, which in turn can be accompanied by severe weight loss.The most severe Klebsiella-related infections are septicemia and meningitis. The former disease corresponds to a severe general infection associated with bacteria and their toxins in the blood. The meningitis they cause, in turn, corresponds to inflammation of the pia mater and arachnoid mater. Klebsiella are accordingly dangerous for patients with weakened immune systems and can even cause deaths, since drugs against the multi-resistant bacteria are now of little help. In addition, the Klebsiella granulomatis subgenus can also become unhealthy for people with normal immune systems. This subgenus is considered the causative agent of granuloma inguinale. Granuloma inguinale corresponds to a bacterial disease with characteristic ulcerative lesions in the genital area. Like all other species of Klebsiella, this subgenus is resistant to penicillin and antibiotics. This makes treatment extremely difficult when the disease occurs. Presumably, the bacterium’s resistance is due to its spread in factory farming. Since preventive antibiotics are permanently used in factory farming, the bacteria have had sufficient time to adapt to the drug. Meanwhile, cross-reactivity has also been observed in association with IgA antibodies and Klebsiella pneumoniae, resulting in targeting of antibodies to the body’s own structures.
