Extended-spectrum beta-lactamase production is associated with an increase in cell invasion and expression of fimbrial adhesins in Klebsiella pneumoniae.
Extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae strains are suggested to possess higher pathogenic potential than non-ESBL producers. Microbial adherence to and invasion of host cells are critical steps in the infection process, so we examined the expression of type 1 and 3 fimbrial adhesins by 58 ESBL-producing and 152 nonproducing isolates of K. pneumoniae and their abilities to invade ileocecal and bladder epithelial cells. Mannose-sensitive hemagglutination of guinea pig erythrocytes and mannose-resistant hemagglutination of ox erythrocytes were evaluated to determine the strains' abilities to express type 1 and type 3 fimbriae, respectively. Bacterial adhesion to and invasion of epithelial cells were tested by enzyme-linked immunosorbent assay and imipenem killing assay, respectively. The adherence of ESBL- and non-ESBL-producing strains to epithelial cells did not differ significantly (P > 0.05). In contrast, the proportion of strains capable of invading (>5% relative invasion) ileocecal and bladder epithelial cells was significantly higher among ESBL producers (81%, n = 47/58, and 27.6%, n = 16/58, respectively) than among non-ESBL producers (61%, n = 93/152, and 10%, n = 15/152, respectively) (P = 0.0084, odds ratio [OR] = 2.711, 95% confidence interval [CI] = 1.302 to 5.643 and P = 0.0021, OR = 4.79, 95% CI = 1.587 to 7.627). The mean invasion by ESBL producers (5.5% +/- 2.8% and 3.3% +/- 2.7%, respectively) was significantly higher than that by non-ESBL producers (2.9% +/- 2.6% and 1.8% +/- 2%, respectively) (P < 0.0001). Likewise, the proportion of ESBL producers coexpressing both fimbrial adhesins was significantly higher (79.3%; n = 46/58) than that of non-ESBL producers (61.8%; n = 94/152) (P = 0.0214; OR = 2,365; 95% CI = 1.157 to 4.834). Upon acquisition of SHV-12-encoding plasmids, two transconjugants switched on to produce type 3 fimbriae while expression of type 1 fimbriae was not affected. The acquisition of an ESBL plasmid appeared to upregulate the phenotypic expression of one or more genes, resulting in greater invasion ability.
Sahly
H
H
Institute for Infection Medicine, Faculty of Medicine, University of Kiel, Kiel, Germany. sahly@labor-lademannbogen.de
Navon-Venezia
S
S
Roesler
L
L
Hay
A
A
Carmeli
Y
Y
Podschun
R
R
Hennequin
C
C
Forestier
C
C
Ofek
I
I
D018829:Adhesins, Bacterial / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001422:Bacterial Adhesion; D002432:Cecum / Q000166:cytology; D002460:Cell Line; D003227:Conjugation, Genetic; D004847:Epithelial Cells / Q000382:microbiology*; D004912:Erythrocytes / Q000382:microbiology / Q000502:physiology; D015964:Gene Expression Regulation, Bacterial; D006168:Guinea Pigs; D006384:Hemagglutination; D006801:Humans; D007082:Ileum / Q000166:cytology; D007711:Klebsiella pneumoniae / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D008826:Microbial Sensitivity Tests; D001743:Urinary Bladder / Q000166:cytology; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000235:genetics
D018829:Adhesins, Bacterial; C107198:beta-lactamase SHV-12; D001618:beta-Lactamases