Dataset Information

Citrobacter spp. as a source of qnrB Alleles.

ABSTRACT: qnrB is the most common of the five qnr families and has the greatest number of allelic variants. Almost two-thirds of the qnrB alleles have been reported in Citrobacter spp., and several were shown to be located on the chromosome. In this study, PCR was used to investigate the prevalence of plasmid-mediated quinolone resistance genes in 71 clinical isolates belonging to the Citrobacter freundii complex. Thirty-seven percent contained qnrB alleles, including 7 (qnrB32 to qnrB38) that were novel and 1 pseudogene, while none contained qnrA, qnrC, qnrD, qnrS, or aac(6')-Ib-cr. When the strains were arrayed by related 16S rRNA sequence and further separated into subspecies by biochemical criteria, clustering of qnrB-positive strains was evident. In only two strains with qnrB2 and qnrB4 was quinolone resistance transferable by conjugation, and only these strains contained the ISCR1 sequence that is often associated with qnrB on plasmids. Five of 26 qnrB-positive strains contained integrase genes, but these included the strains with qnrB2 and qnrB4 as well as two strains with other transmissible plasmids. In a fully sequenced genome of Citrobacter youngae, a member of the C. freundii complex, another novel qnrB allele, qnrB39, occurs in a sequence of genes that is 90% identical to sequence surrounding integron-associated qnrB4 incorporated into plasmids. The chromosome of Citrobacter is the likely source of plasmid-mediated qnrB.

SUBMITTER: Jacoby GA

PROVIDER: S-EPMC3195048 | biostudies-literature | 2011 Nov

REPOSITORIES: biostudies-literature

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Citrobacter spp. as a source of qnrB Alleles.

Jacoby George A GA Griffin Caitlin M CM Hooper David C DC

Antimicrobial agents and chemotherapy 20110815 11

qnrB is the most common of the five qnr families and has the greatest number of allelic variants. Almost two-thirds of the qnrB alleles have been reported in Citrobacter spp., and several were shown to be located on the chromosome. In this study, PCR was used to investigate the prevalence of plasmid-mediated quinolone resistance genes in 71 clinical isolates belonging to the Citrobacter freundii complex. Thirty-seven percent contained qnrB alleles, including 7 (qnrB32 to qnrB38) that were novel ...[more]

PMID: 21844311

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Project description:The emergence of carbapenem resistance is a significant public health concern. The rate of infections caused by carbapenemase-producing Citrobacter spp., particularly C. freundii, is increasing. Concomitantly, comprehensive global genomic data on carbapenemase-producing Citrobacter spp. are scarce. We used short read whole-genome sequencing to describe the molecular epidemiology and international distribution of eighty-six carbapenemase-producing Citrobacter spp. obtained from two surveillance programs (2015 to 17). The common carbapenemases were KPC-2 (26%), VIM-1 (17%), IMP-4 (14%) and NDM-1 (10%). C. freundii and C. portucalensis were the principal species. C. freundii consisted of multiple clones obtained mainly from Colombia (with KPC-2), the United States (with KPC-2, -3), and Italy (with VIM-1). Two dominant C. freundii clones were identified: ST98 was linked with blaIMP-8 from Taiwan and blaKPC-2 from the United States, and ST22 was linked with blaKPC-2 from Colombia and blaVIM-1 from Italy. C. portucalensis consisted mainly of two clones: ST493 with blaIMP-4 which was limited to Australia, and ST545 with blaVIM-31 which was limited to Turkey. Class I integron (In916) with blaVIM-1 was circulating between multiple sequence types (STs) in Italy, Poland, and Portugal. In73 with blaIMP-8 was circulating between various STs in Taiwan, while In809 with blaIMP-4 was circulating between different STs in Australia. The global carbapenemase-producing Citrobacter spp. population is dominated by diverse STs with different characteristics and varied geographical distribution and thus requires continued monitoring. Ongoing genomic surveillance should use methodologies able to distinguish between C. freundii and C. portucalensis. IMPORTANCE Citrobacter spp. are gaining recognition as important causes of hospital-acquired infections in humans. Among Citrobacter spp., carbapenemase-producing strains are cause of utmost concern to health care services globally due to their ability to resist therapy with virtually any beta-lactam antibiotic. Here, we described the molecular characteristics of a global collection of carbapenemase-producing Citrobacter spp. C. freundii and C. portucalensis were the most common species among Citrobacter spp. with carbapenemases from this survey. Importantly, C. portucalensis was misidentified as C. freundii when using Vitek 2.0/MALDI-TOF MS (matrix-assisted laser desorption/ionization-time of flight mass spectrometry) phenotypic identification, which has important implications for future surveys. Among C. freundii, we identified two dominant clones: ST98 with blaIMP-8 from Taiwan and blaKPC-2 from the United States, and ST22 with blaKPC-2 from Colombia and blaVIM-1 from Italy. As for C. portucalensis, the dominant clones consisted of ST493 with blaIMP-4 from Australia and ST545 with blaVIM-31 from Turkey.

Dataset Information

Citrobacter spp. as a source of qnrB Alleles.

Publications

Citrobacter spp. as a source of qnrB Alleles.

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