Hypermucoviscous Klebsiella Syndrome Without Liver Abscess in a Patient With Immunoglobulin G2 Immune Deficiency

Klebsiella pneumoniae is an important Gram-negative bacilli capable of causing both community- and hospital-acquired infections. There have been numerous case reports of K pneumoniae causing community-acquired primary liver abscesses, most of which have been reported in Taiwan and other regions in South-East (SE) Asia. Strains of the organism possessing magA or rmpA (regulator of mucoid phenotype) are capable of producing large amounts of polysaccharide capsule, making them resistant to serum killing and phagocytosis. The gene encoding magA is a virulence marker specific to the K1 serotype found in a significant proportion of invasive strains, and its presence has been correlated with a greater lethality in a mouse model [1, 2]. We report what we believe to be the first case report of a patient with hypermucoviscous K pneumoniae without liver abscess and in the setting of an immunoglobulin (Ig)G2 subclass deficiency.