<i>Klebsiella pneumoniae</i>
            Capsule Expression Is Necessary for Colonization of Large Intestines of Streptomycin-Treated Mice

Favre-Bonté, Sabine; Licht, Tine Rask; Forestier, Christiane; Krogfelt, Karen A.

doi:10.1128/iai.67.11.6152-6156.1999

Cited by 69 publications

(40 citation statements)

References 16 publications

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“…This is in accordance with a previous study where non-capsulated mutants of K. pneumoniae strains were observed to be as e¡ective colonizers of the intestine of germfree chickens as the capsulated wild-type strains [12]. In one study, the colonization ability of a capsule defective mutant of K. pneumoniae strain LM21 was sig-ni¢cantly attenuated [13]. Here, the capsule defective mutant was found to form aggregates during growth in the intestine, which could explain the inability of this particular mutant to e¡ectively colonize the intestine.…”

Section: Discussionsupporting

confidence: 92%

“…The role of capsule in serum poor compartments is less clari¢ed. Only one study has investigated the role of capsule in K. pneumoniae UTI with inconclusive results [11] and studies on the role of capsule in GI colonization are contradictory [12,13]. Interestingly, recent studies have shown that expression of capsule impedes the ability of K. pneumoniae to adhere to and invade epithelial cells in vitro [14,15].…”

Section: Introductionmentioning

confidence: 99%

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Role of capsule in Klebsiella pneumoniae virulence: lack of correlation between in vitro and in vivo studies

Struve

2003

FEMS Microbiology Letters

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In vitro and in vivo models were used to investigate the role of capsule on the virulence of Klebsiella pneumoniae. We showed that capsule expression reduces dramatically the ability of the K. pneumoniae to bind to epithelial cells when compared to its non-capsulated variant. The presence/absence of capsule had no effect on the colonization of the gastrointestinal tract, while in the urinary tract we established that capsule is an important virulence factor. Our study demonstrates the caution needed when extrapolating from results of in vitro studies and emphasizes the necessity of in vivo models in studies of bacterial virulence.

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Section: Discussionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Role of capsule in Klebsiella pneumoniae virulence: lack of correlation between in vitro and in vivo studies

Struve

2003

FEMS Microbiology Letters

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“…Recently a deep-rough mutant of the commensal E. coli K-12 strain MG1655 was shown to be reduced in its ability to colonize the mouse intestinal tract due to increased tendency to clump in the intestinal mucus [27]. Similarly, capsular polysaccharides have been proposed to contribute to intestinal colonization by several Gram-negative pathogens including E. coli [33,34]. In Vibrio cholerae O139 both LPS and capsular polysaccharide play an important role in the colonization process [35].…”

Section: Discussionmentioning

confidence: 99%

Transcriptional regulation through RfaH contributes to intestinal colonization byEscherichia coli

Nagy

Dobrindt

Grozdanov

et al. 2005

FEMS Microbiology Letters

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The Escherichia coli regulatory protein RfaH contributes to efficient colonization of the mouse gut. Extraintestinal pathogenic (ExPEC) as well as non-pathogenic probiotic E. coli strains rapidly outcompeted their isogenic rfaH mutants following oral mixed infections. LPS-core and O-antigen side-chain as well as capsular polysaccharide synthesis are among the E. coli virulence factors affected by RfaH. In respect of colonization, deep-rough LPS mutants (waaG) but not capsular (kps) mutants were shown to behave similarly to rfaH mutants. Furthermore, alteration in the length of O-antigen side-chains did not modify colonization ability either indicating that it was the regulatory effect of RfaH on LPS-core synthesis, which affected intestinal colonization. Loss of RfaH did not significantly influence adhesion of bacteria to cultured colon epithelial cells. Increased susceptibility of rfaH mutants to bile salts, on the other hand, suggested that impaired in vivo survival could be responsible for the reduced colonization capacity.

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“…In K. pneumoniae , capsule expression interferes with adhesion to epithelial cells in vitro and is associated with a decrease in transcription of an adhesin-encoding gene (Favre-Bonte et al ., 1999a;Sahly et al ., 2000). However, capsule expression is still required for colonization in mouse models (Favre-Bonte et al ., 1999b).…”

Section: Introductionmentioning

confidence: 99%

Transcriptional organization and regulation of the Escherichia coli K30 group 1 capsule biosynthesis (cps) gene cluster

Rahn

Whitfield²

2003

Molecular Microbiology

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SummaryEscherichia coli group 1 capsules are important virulence determinants, yet little is known about the transcriptional organization or regulation of their biosynthetic ( cps ) operons. Transcription of the prototype serotype K30 cluster is modulated by the JUMPStart-RfaH antitermination mechanism, with the cps promoter being localized to a region immediately upstream of the JUMPStart sequence. A putative stem-loop structure located within the K30 cps cluster separates conserved genes with products that are required for surface expression of capsule from serotype-specific genes encoding enzymes for polymer repeat-unit synthesis and polymerization. This putative stem-loop structure significantly reduces transcription in a termination-probe vector and may contribute to differential expression of the cps genes. Previous work indicated that increased amounts of group 1 capsular polysaccharide synthesis resulted from the overexpression of the Rcs (regulator of capsule synthesis) proteins. However, neither overexpression of the transcriptional activator RcsB nor an rcsB :: aadA chromosomal insertion altered the level of transcription measured by cps::lacZ fusions. In the group 1 strains examined, an RcsAB box was found immediately upstream of galF , a gene involved in the production of sugar nucleotide precursors. Overexpression of RcsB was found to result in a threefold increase in transcription of a galF::lacZ chromosomal fusion. Moreover, overexpression of GalF gave rise to a two-to threefold increase in cell-free as well as cellassociated capsule, without affecting cps::lacZ activity. These results indicate that transcription of the E. coli group 1 capsule cluster itself is not regulated by the Rcs system and may, in fact, be constitutive. However, the Rcs system can potentially influence levels of capsular polysaccharide production by increasing galF transcription and influencing the available pool of biosynthetic precursors.

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Klebsiella pneumoniae Capsule Expression Is Necessary for Colonization of Large Intestines of Streptomycin-Treated Mice

Cited by 69 publications

References 16 publications

Role of capsule in Klebsiella pneumoniae virulence: lack of correlation between in vitro and in vivo studies

Role of capsule in Klebsiella pneumoniae virulence: lack of correlation between in vitro and in vivo studies

Transcriptional regulation through RfaH contributes to intestinal colonization byEscherichia coli

Transcriptional organization and regulation of the Escherichia coli K30 group 1 capsule biosynthesis (cps) gene cluster

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