Regulator of the mucoid phenotype A gene increases the virulent ability of extended-spectrum beta-lactamase-producing serotype non-K1/K2 Klebsiella pneumonia.
BACKGROUND
To determine whether the presence of a capsule regulator gene [i.e., regulator of mucoid phenotype A (rmpA) gene] contributes to virulence on extended-spectrum β-lactamase-producing Klebsiella pneumoniae (ESBL-KP) with serotype non-K1/K2 strains.


METHODS
Twenty-eight ESBL-KP and non-ESBL-KP isolates were collected from the Tri-Service General Hospital (Taipei, Taiwan). The impact of the virulent rmpA gene in different capsular polysaccharide serotypes on ESBL-KP and non-ESBL-KP isolates was studied by a neutrophil phagocytosis reaction, a serum bactericidal assay, and an animal survival model.


RESULTS
Resistance to broad spectrum antibiotics was more prevalent in ESBL-KP strains than in non-ESBL-KP strains (p < 0.01). The ESBL-KP strains had different molecular patterns from non-ESBL-KP strains, based on pulsed-field gel electrophoresis. The frequency of serum-resistant isolates was the highest among ESBL-KP strains with rmpA (i.e., rmpA(+)) [71.4% (5/7)] than among of non-ESBL-KP rmpA(+) strains [42.8% (6/14)], ESBL-KP strains without rmpA (rmpA(-)) [33.3% (7/21)], and non-ESBL-KP rmpA(-) strains [14.2% (2/14)]. The most significant increase in neutrophil resistance occurred in the ESBL-KP rmpA(+) strains in comparison to the non-ESBL-KP rmpA(+), ESBL-KP rmpA(-), and non-ESBL-KP rmpA(-) strains (p < 0.01). The results of the animal survival model were compatible with the neutrophil phagocytosis reaction and serum bactericidal assay.


CONCLUSION
We conclude that the pathogenic potential is greater in rmpA(+) ESBL-KP strains than in rmpA(-) ESBL-KP and non-ESBL-KP strains.
['Lin|Hsin-An|HA|', 'Huang|Ya-Li|YL|', 'Yeh|Kao-Ming|KM|', 'Siu|L K|LK|', 'Lin|Jung-Chung|JC|', 'Chang|Feng-Yee|FY|']
D000818:Animals D000900:Anti-Bacterial Agents D016667:Bacterial Capsules D001426:Bacterial Proteins D016521:Electrophoresis, Gel, Pulsed-Field D006801:Humans D007710:Klebsiella Infections D007711:Klebsiella pneumoniae D008297:Male D051379:Mice D008807:Mice, Inbred BALB C D009504:Neutrophils D010587:Phagocytosis D065288:Serogroup D013624:Taiwan D001618:beta-Lactamases
Klebsiella pneumoniae regulator of mucoid phenotype A β-lactamase-producing Klebsiella pneumonia