Klebsiella pneumoniae бактериясы: сипаттамасы, аурулары мен маңызы

Species of bacterium

Klebsiella pneumoniae is a Gram negative, non motile, encapsulated, lactose fermenting, facultative anaerobic, rod shaped bacterium. It appears as a mucoid lactose fermenter on MacConkey agar. Although found in the normal flora of the mouth, skin, and intestines, it can cause destructive changes to human and animal lungs if aspirated, specifically to the alveoli resulting in bloody, brownish or yellow colored jelly like sputum. In the clinical setting, it is the most significant member of the genus Klebsiella of the Enterobacteriaceae. K. oxytoca and K. rhinoscleromatis have also been demonstrated in human clinical specimens. In recent years, Klebsiella species have become important pathogens in nosocomial infections. It naturally occurs in the soil, and about 30% of strains can fix nitrogen in anaerobic conditions. As a free living diazotroph, its nitrogen fixation system has been much studied, and is of agricultural interest, as K. pneumoniae has been demonstrated to increase crop yields in agricultural conditions. It is closely related to K. oxytoca from which it is distinguished by being indole negative and by its ability to grow on melezitose but not 3 hydroxybutyrate.

The genus Klebsiella was named after the German microbiologist Edwin Klebs (1834–1913). It is also known as Friedlander's bacillum in honor of Carl Friedländer, a German pathologist, who proposed that this bacterium was the etiological factor for the pneumonia seen especially in immunocompromised individuals such as people with chronic diseases or alcoholics. Community acquired pneumonia caused by Klebsiella pneumoniae may occasionally be called Friedländer's pneumonia.

Illness most commonly affects middle aged and older men more often than women with debilitating diseases. This patient population is believed to have impaired respiratory host defenses, including persons with diabetes, alcoholism, malignancy, liver disease, chronic obstructive pulmonary diseases, glucocorticoid therapy, kidney failure, and certain occupational exposures (such as papermill workers). Many of these infections are obtained when a person is in the hospital for some other reason (a nosocomial infection). In addition to pneumonia, Klebsiella can also cause infections in the urinary tract, lower biliary tract, and surgical wound sites. The range of clinical diseases includes pneumonia, thrombophlebitis, urinary tract infection, cholecystitis, diarrhea, upper respiratory tract infection, wound infection, osteomyelitis, meningitis, and bacteremia, and sepsis. For patients with an invasive device in their bodies, contamination of the device becomes a risk; neonatal ward devices, respiratory support equipment, and urinary catheters put patients at increased risk. Also, the use of antibiotics can be a factor that increases the risk of nosocomial infection with Klebsiella bacteria. Sepsis and septic shock can follow entry of the bacteria into the blood. Research conducted at King's College, London has implicated molecular mimicry between HLA B27 and two Klebsiella surface molecules as the cause of ankylosing spondylitis. Klebsiella ranks second to E. coli for urinary tract infections in older people. It is also an opportunistic pathogen for patients with chronic pulmonary disease, enteric pathogenicity, nasal mucosa atrophy, and rhinoscleroma. New antibiotic resistant strains of K. pneumoniae are appearing.

The most common condition caused by Klebsiella bacteria outside the hospital is pneumonia, typically in the form of bronchopneumonia and also bronchitis. These patients have an increased tendency to develop lung abscesses, cavitation, empyema, and pleural adhesions. It has a death rate around 50%, even with antimicrobial therapy.

It is typically due to aspiration and alcoholism may be a risk factor, though it is also commonly implicated in hospital acquired urinary tract infections, and COPD (chronic obstructive pulmonary disease) individuals.

Individuals with Klebsiella pneumoniae tend to cough up a characteristic sputum, as well as having fever, nausea, tachycardia, and vomiting. Klebsiella pneumoniae tends to affect people with underlying conditions, such as alcoholism.

Hypervirulent (hvKp) is a rather recent K pneumoniae variant that is significantly more virulent than classical K. pneumoniae (cKp). While cKp is an opportunistic pathogen responsible for nosocomial infections that usually affect immunocompromised patients, hvKp is clinically more concerning since it also causes disease in healthy individuals and can infect virtually every site of the body. The genetic traits that lead to this pathotype are included in a large virulence plasmid and potentially on additional conjugative elements. These newly identified strains were described to overproduce capsule components and siderophores for iron acquisition, among other factors. Although initial studies showed that hvKp is rather susceptible to antibiotic treatment, it has been recently shown that such strains can acquire resistance plasmids and become multiresistant to a variety of antibiotics. It originated from Asia, having a high mortality rate among the population. It often spreads to central nervous system and eye causing endophthalmitis, nonhepatic abscesses, pneumonia, necrotizing fasciitis, and meningitis. One visual trait of these strains is hypermucoviscous phenotype and a string test can be used to help the diagnosis. Further examinations and treatments are made on a case by case basis, as there are currently no international guidelines.

Klebsiella pneumoniae carries a large number of anti microbial resistance genes (AMR genes). These genes are transferred via plasmids from and to other human pathogens. One human pathogen that commonly acquires AMR genes from Klebsiella pneumoniae is Salmonella. This could help with treatment of salmonella infections due to having knowledge of possible antibiotic resistance data. The majority of AMR genes in Klebsiella pneumoniae are plasmid borne. An example of a niche would be soil, often considered a hotspot for gene transfer. +Total AMR genes per sppAverage plasmidsAcinetobacter baumannii2781.5Pseudomonas aeruginosa2630Klebsiella pneumoniae4102.5Enterobacter cloacae2772.2Escherichia coli2041
The table shows the number of AMR genes and plasmids (per strain or subspecies) compared to other common bacteria species. which may include strict adherence to hand hygiene (preferably using an alcohol based hand rub (60–90%) or soap and water if hands are visibly soiled. Alcohol based hand rubs are effective against these Gram negative bacilli) and wearing gowns and gloves when they enter rooms where patients with Klebsiella–related illnesses are housed. Healthcare facilities also must follow strict cleaning procedures to prevent the spread of Klebsiella.

Multiple drug resistant K. pneumoniae strains have been killed in vivo by intraperitoneal, intravenous, or intranasal administration of phages in laboratory tests. Resistance to phages is not likely to be as troublesome as to antibiotics as new infectious phages are likely to be available in environmental reservoirs. Phage therapy can be used in conjunction with antibiotics, to supplement their activity instead of replacing it altogether.

New data sources outlining the global burden of K. pneumoniae and drug resistant forms are expected to build momentum into prophylactic vaccine development. The recent 2022 IHME study showed that in 2019 K. pneumoniae was responsible for 790,000 deaths [571,000–1,060,000] in all age groups across 11 infectious syndromes. Importantly, in Sub saharan Africa K. pneumoniae was responsible for 124,000 [89,000–167,000] neonatal deaths due to bloodstream infections. Based on these and other data, a newly developed prophylactic vaccine would ideally be designed to prevent invasive K. pneumoniae disease in both vulnerable persons but also as a maternal vaccine to prevent neonatal sepsis and global demand assessments have been published. As of June 2023, one single clinical development program for a K. pneumoniae vaccine [Kleb4V/GSK4429016A] was in a Phase 1/2 study in healthy adults aged 18–70 yrs (n=166) [Clinical trials identifier: NCT04959344]. The vaccine is an O antigen based conjugate where the specific O antigens in the vaccine remain undisclosed [Michael Kowarik, LimmaTech Biologics, World Vaccine Congress EU, 2022] although only a limited number of O serotypes can account for a high proportion of clinical isolates. A recent Q1 2024 GSK Corporate R&D pipeline update showed that Kleb4V/GSK4429016A had been removed. The status of the program is now subject to verification.