Faculty Opinions recommendation of The Widespread Multidrug-Resistant Serotype O12 Pseudomonas aeruginosa Clone Emerged through Concomitant Horizontal Transfer of Serotype Antigen and Antibiotic Resistance Gene Clusters.

Author(s):  
Burkhard Tümmler
mBio ◽  
2015 ◽  
Vol 6 (5) ◽  
Author(s):  
Sandra Wingaard Thrane ◽  
Véronique L. Taylor ◽  
Luca Freschi ◽  
Irena Kukavica-Ibrulj ◽  
Brian Boyle ◽  
...  

ABSTRACTThe O-specific antigen (OSA) inPseudomonas aeruginosalipopolysaccharide is highly varied by sugar identity, side chains, and bond between O-repeats. These differences classifiedP. aeruginosainto 20 distinct serotypes. In the past few decades, O12 has emerged as the predominant serotype in clinical settings and outbreaks. These serotype O12 isolates exhibit high levels of resistance to various classes of antibiotics. Here, we explore how theP. aeruginosaOSA biosynthesis gene clusters evolve in the population by investigating the association between the phylogenetic relationships among 83P. aeruginosastrains and their serotypes. While most serotypes were closely linked to the core genome phylogeny, we observed horizontal exchange of OSA biosynthesis genes among phylogenetically distinctP. aeruginosastrains. Specifically, we identified a “serotype island” ranging from 62 kb to 185 kb containing theP. aeruginosaO12 OSA gene cluster, an antibiotic resistance determinant (gyrAC248T), and other genes that have been transferred betweenP. aeruginosastrains with distinct core genome architectures. We showed that these genes were likely acquired from an O12 serotype strain that is closely related toP. aeruginosaPA7. Acquisition and recombination of the “serotype island” resulted in displacement of the native OSA gene cluster and expression of the O12 serotype in the recipients. Serotype switching by recombination has apparently occurred multiple times involving bacteria of various genomic backgrounds. In conclusion, serotype switching in combination with acquisition of an antibiotic resistance determinant most likely contributed to the dissemination of the O12 serotype in clinical settings.IMPORTANCEInfection rates in hospital settings by multidrug-resistant (MDR)Pseudomonas aeruginosaclones have increased during the past decades, and serotype O12 is predominant among these epidemic strains. It is not known why the MDR phenotype is associated with serotype O12 and how this clone type has emerged. This study shows that evolution of MDR O12 strains involved a switch from an ancestral O4 serotype to O12. Serotype switching was the result of horizontal transfer and genetic recombination of lipopolysaccharide (LPS) biosynthesis genes originating from an MDR taxonomic outlierP. aeruginosastrain. Moreover, the recombination event also resulted in acquisition of antibiotic resistance genes. These results impact on our understanding of MDR outbreak strain and serotype evolution and can potentially assist in better monitoring and prevention.


2001 ◽  
Vol 45 (11) ◽  
pp. 2991-3000 ◽  
Author(s):  
Bianca Hochhut ◽  
Yasmin Lotfi ◽  
Didier Mazel ◽  
Shah M. Faruque ◽  
Roger Woodgate ◽  
...  

ABSTRACT Many recent Asian clinical Vibrio cholerae E1 Tor O1 and O139 isolates are resistant to the antibiotics sulfamethoxazole (Su), trimethoprim (Tm), chloramphenicol (Cm), and streptomycin (Sm). The corresponding resistance genes are located on large conjugative elements (SXT constins) that are integrated into prfC on the V. cholerae chromosome. We determined the DNA sequences of the antibiotic resistance genes in the SXT constin in MO10, an O139 isolate. In SXTMO10, these genes are clustered within a composite transposon-like structure found near the element's 5′ end. The genes conferring resistance to Cm (floR), Su (sulII), and Sm (strA and strB) correspond to previously described genes, whereas the gene conferring resistance to Tm, designated dfr18, is novel. In some other O139 isolates the antibiotic resistance gene cluster was found to be deleted from the SXT-related constin. The El Tor O1 SXT constin, SXTET, does not contain the same resistance genes as SXTMO10. In this constin, the Tm resistance determinant was located nearly 70 kbp away from the other resistance genes and found in a novel type of integron that constitutes a fourth class of resistance integrons. These studies indicate that there is considerable flux in the antibiotic resistance genes found in the SXT family of constins and point to a model for the evolution of these related mobile elements.


2004 ◽  
Vol 48 (10) ◽  
pp. 3806-3812 ◽  
Author(s):  
Benoît Doublet ◽  
François-Xavier Weill ◽  
Laetitia Fabre ◽  
Elisabeth Chaslus-Dancla ◽  
Axel Cloeckaert

ABSTRACT Salmonella genomic island 1 (SGI1) harbors an antibiotic resistance gene cluster and was previously identified in the multidrug-resistant Salmonella enterica serovars Typhimurium DT104, Agona, Paratyphi B, and Albany. This antibiotic resistance gene cluster is a complex class 1 integron and most often confers resistance to ampicillin (Ap), chloramphenicol (Cm)/florfenicol (Ff), streptomycin (Sm)/spectinomycin (Sp), sulfonamides (Su), and tetracycline (Tc) (ApCmFfSmSpSuTc profile). Recently, variant SGI1 antibiotic resistance gene clusters conferring different antibiotic resistance profiles have been identified in several S. enterica serovars and were classified as SGI1-A to -G. We identified a new variant SGI1 antibiotic resistance gene cluster in two multidrug-resistant S. enterica serovar Newport strains isolated from humans in France. In these strains, the Sm/Sp resistance gene cassette aadA2 inserted at the first attI1 site was replaced by two other aminoglycoside resistance gene cassettes. The first one contains a new resistance gene encoding an AAC(3)-I aminoglycoside 3-N-acetyltransferase that confers resistance to gentamicin (Gm) and sisomicin (Sc). This gene has been named aac(3)-Id. The second one harbors the Sm/Sp resistance gene aadA7. This gene cassette replacement in the SGI1 complex integron of serovar Newport strains constitutes a new variant SGI1 antibiotic resistance gene cluster named SGI1-H. The occurrence of SGI1 in different S. enterica serovars, now including serovar Newport, strengthens the hypothesis of horizontal transfer of SGI1.


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