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Klebsiella pneumoniae is among the most common gram-negative bacteria encountered by physicians worldwide. It is a common hospital-acquired pathogen, causing urinary tract infections, nosocomial pneumonia, and intraabdominal infections. K. pneumoniae is also a potential community-acquired pathogen. In this international collaborative study, we evaluated geographic differences and trends in three prominent presentations of community-acquired Klebsiella infection.
Klebsiella pneumoniae is a gram-negative rod-shaped bacteria, and clinically the most important member of the Klebsiella genus of Enterobacteriaceae. It can cause pneumonia although it is more commonly implicated in hospital-acquired urinary tract and wound infections, particularly in people with weakened immune systems. It is an increasing problem on hospitals because of the problem of antibiotic resistant strains.
The genus Klebsiella belongs to the tribe Klebsiellae, a member of the family Enterobacteriaceae. The organisms are named after Edwin Klebs, a 19th century German microbiologist. Klebsiellae are nonmotile, rod-shaped, gram-negative bacteria with a prominent polysaccharide capsule. This capsule accounts for their large appearance on samples stained with Gram stain. Serotypes are based on the structural variability of the capsular polysaccharides (K antigens) and lipopolysaccharides (O antigens). There are 77 K antigens and 8 O antigens. The virulence of all serotypes appears to be similar.
Klebsiellae are ubiquitous in nature. In humans, they may colonize the skin, pharynx, or gastrointestinal tract. They may also colonize sterile wounds and urine. Carriage rates vary with different studies. Klebsiellae may be regarded as normal flora in many parts of the colon and intestinal tract and in the biliary tract. Oropharyngeal carriage has been associated with endotracheal intubation, impaired host defenses, and antimicrobial use.
K pneumoniae and K oxytoca are the 2 members of this genus responsible for most human infections. They are opportunistic pathogens found in the environment and in mammalian mucosal surfaces. The principal pathogenic reservoirs of infection are the gastrointestinal tract of patients and the hands of hospital personnel. Organisms can spread rapidly, often leading to nosocomial outbreaks.
Infection with Klebsiella organisms occurs in the lungs, where they cause destructive changes. Necrosis, inflammation, and hemorrhage occur within lung tissue, sometimes producing a thick, bloody, mucoid sputum described as currant jelly sputum. The illness typically affects middle-aged and older men with debilitating diseases such as alcoholism, diabetes, or chronic bronchopulmonary disease. This patient population is believed to have impaired respiratory host defenses. The organisms gain access after the host aspirates colonizing oropharyngeal microbes into the lower respiratory tract.
Klebsiellae have also been incriminated in nosocomial infections. Common sites include the urinary tract, lower respiratory tract, biliary tract, and surgical wound sites. The spectrum of clinical syndromes includes pneumonia, bacteremia, thrombophlebitis, urinary tract infection (UTI), cholecystitis, diarrhea, upper respiratory tract infection, wound infection, osteomyelitis, and meningitis. The presence of invasive devices, contamination of respiratory support equipment, use of urinary catheters, and use of antibiotics are factors that increase the likelihood of nosocomial infection with Klebsiella species. Sepsis and septic shock may follow entry of organisms into the blood from a focal source.
Rhinoscleroma and ozena are 2 other infections caused by Klebsiella species. These diseases are rare. Rhinoscleroma is a chronic inflammatory process involving the nasopharynx, whereas ozena is a chronic atrophic rhinitis characterized by necrosis of nasal mucosa and mucopurulent nasal discharge.
Klebsiella Pneumonia Causes
Klebsiella Pneumonia Symptoms
Klebsiella Pneumonia Diagniosis and Treatment
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