Klebsiella infection

Overview
Klebsiella infection are primarily associated with Klebsiella pneumoniae.

K. pneumoniae can cause bacterial pneumonia, typically due to aspiration by alcoholics, though it is more commonly implicated in hospital-acquired urinary tract and wound infections, particularly in immunocompromised individuals.

Presentation
Patients with Klebsiella pneumonia tend to cough up a characteristic sputum that is said to resemble "red-currant jelly". Klebsiella ranks second to E. coli for urinary tract infections in older persons. It is also an opportunistic pathogen for patients with chronic pulmonary disease, enteric pathogenicity, nasal mucosa atrophy, and rhinoscleroma. Feces are the most significant source of patient infection, followed by contact with contaminated instruments.

Members of the Klebsiella genus typically express 2 types of antigens on their cell surface. The first, O antigen, is a lipopolysaccharide of which 9 varieties exist. The second is K antigen, a capsular polysaccharide with more than 80 varieties. Both contribute to pathogenicity and form the basis for subtyping.

Research conducted at King's College, London has implicated molecular mimicry between HLA-B27 and two molecules in Klebsiella microbes as the cause of ankylosing spondylitis. As a general rule, Klebsiella infections tend to occur in people with a weakened immune system from improper diet. Many of these infections are obtained when a person is in the hospital for some other reason. The most common infection caused by Klebsiella bacteria outside the hospital is pneumonia.

Klebsiella pneumonia tends to affect people with underlying diseases, such as alcoholism, diabetes and chronic lung disease.

Treatment
Klebsiella possesses a chromosomal class a beta-lactamase giving it resistance to ampicillin. Many strains have acquired an extended-spectrum beta-lactamase with additional resistance to carbenicillin, amoxiciline, beta-lactamase, and increasingly to ceftazidime. The bacteria remain largely susceptible to aminoglycosides and cephalosporins. Varying degrees of inhibition of the beta-lactamase with clavulanic acid have been reported. Infections due to multidrug-resistant Gram-negative pathogens in the ICU have invoked the re-emergence of colistin, an antibiotic that had rarely been used for decades. However, colistin-resistant strains of K. pneumoniae have been reported in Greek ICUs.

Eponym
Community-acquired pneumonia caused by Klebsiella pneumoniae may be called Friedländer's Pneumonia, after Carl Friedländer.