Molecular epidemiology provides evidence of genotypic heterogeneity of multidrug-resistant Pseudomonas aeruginosa serotype O:12 outbreak isolates from a pediatric hospital.

ABSTRACT From May 1997 to December 2001, a serotype O:6 multidrug-resistant strain of Pseudomonas aeruginosa colonized or infected 201 patients in the University Hospital of Besançon (France). The susceptibility profile of this epidemic clone to fluoroquinolones and aminoglycosides was relatively stable during the outbreak but showed important isolate-to-isolate variations (up to 64-fold) in the MICs of β-lactams. Analysis of 18 genotypically related isolates selected on a quaterly basis demonstrated alterations in the two DNA topoisomerases II and IV (Thr83→Ile in GyrA and Ser87→Leu in ParC) and production of an ANT(2")-I enzyme. Although constitutively overproduced in these bacteria, the MexXY efflux system did not appear to contribute significantly to aminoglycoside resistance. β-Lactam resistance was associated with derepression of intrinsic AmpC β-lactamase (with isolate-to-isolate variations of up to 58-fold) and sporadic deficiency in a 46-kDa protein identified as the carbapenem-selective porin OprD. Of the 18 isolates, 14 were also found to overproduce the efflux system MexAB-OprM as a result of alteration of the repressor protein MexR (His107→Pro). However, complementation experiments with the cloned mexR gene demonstrated that MexAB-OprM contributed only marginally to β-lactam and fluoroquinolone resistance. Of the four isolates exhibiting wild-type MexAB-OprM expression despite the MexR alteration, two appeared to harbor secondary mutations in the mexA-mexR intergenic region and one harbored secondary mutations in the putative ribosome binding site located upstream of the mexAB oprM operon. In conclusion, this study shows that many mechanisms were involved in the multiresistance phenotype of this highly epidemic strain of P. aeruginosa. Our results also demonstrate that the clone sporadically underwent substantial genetic and phenotypic variations during the course of the outbreak, perhaps in relation to local or individual selective drug pressures.

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Molecular Epidemiology of Metallo-β-Lactamase-Producing Pseudomonas aeruginosa Isolates from Norway and Sweden Shows Import of International Clones and Local Clonal Expansion

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00824-09 ◽

2009 ◽

Vol 54 (1) ◽

pp. 346-352 ◽

Cited By ~ 106

Author(s):

Ørjan Samuelsen ◽

Mark A. Toleman ◽

Arnfinn Sundsfjord ◽

Johan Rydberg ◽

Truls M. Leegaard ◽

...

Keyword(s):

Risk Factors ◽

Pseudomonas Aeruginosa ◽

Antimicrobial Resistance ◽

Molecular Epidemiology ◽

Clonal Expansion ◽

Multidrug Resistant ◽

Gram Negative Bacteria ◽

Gram Negative ◽

Low Prevalence

ABSTRACT Scandinavia is considered a region with a low prevalence of antimicrobial resistance. However, the number of multidrug-resistant (MDR) Gram-negative bacteria is increasing, including metallo-β-lactamase (MBL)-producing Pseudomonas aeruginosa. In this study MBL-producing P. aeruginosa isolates identified in Norway (n = 4) and Sweden (n = 9) from 1999 to 2007 were characterized. Two international clonal complexes (CC), CC111 (n = 8) and CC235 (n = 2), previously associated with MBL-producing isolates, were dominant. CC111 isolates (ST111/229; serotype O12; bla VIM-2) included clonally related isolates identified in Skåne County, Sweden (n = 6), and two isolates associated with importation from Greece and Denmark. In all CC111 isolates, bla VIM-2 was located in integron In59.2 or In59 variants. The two CC235 isolates (ST235/ST230; serotype O11; bla VIM-4) were imported from Greece and Cyprus, were possibly clonally related, and carried bla VIM-4 in two different integron structures. Three isolates imported from Ghana (ST233; serotype O6; bla VIM-2), Tunisia (ST654; serotype O11; bla VIM-2), and Thailand (ST260; serotype O6; bla IMP-14) were clonally unrelated. ST233 was part of a new CC (CC233) that included other MBL-producing isolates, while ST654 could also be part of a new CC associated with MBL producers. In the isolates imported from Ghana and Tunisia, bla VIM-2 was part of unusual integron structures lacking the 3′ conserved segment and associated with transposons. The bla VIM gene was found to be located on the chromosome in all isolates. Known risk factors for acquisition of MBL were reported for all patients except one. The findings suggest that both import of successful international clones and local clonal expansion contribute to the emergence of MBL-producing P. aeruginosa in Scandinavia.

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Clinical outcomes, molecular epidemiology and resistance mechanisms of multidrug-resistant Pseudomonas aeruginosa isolated from bloodstream infections from Qatar

Annals of Medicine ◽

10.1080/07853890.2021.2012588 ◽

2021 ◽

Vol 53 (1) ◽

pp. 2345-2353

Author(s):

Mazen A. Sid Ahmed ◽

Jemal M. Hamid ◽

Ahmed A. Husain ◽

Hamad Abdel Hadi ◽

Sini Skariah ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Molecular Epidemiology ◽

Clinical Outcomes ◽

Bloodstream Infections ◽

Multidrug Resistant ◽

Resistance Mechanisms

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Molecular Surveillance of European Quinolone-Resistant Clinical Isolates of Pseudomonas aeruginosa andAcinetobacter spp. Using Automated Ribotyping

Journal of Clinical Microbiology ◽

10.1128/jcm.38.10.3636-3645.2000 ◽

2000 ◽

Vol 38 (10) ◽

pp. 3636-3645 ◽

Cited By ~ 39

Author(s):

Sylvain Brisse ◽

Dana Milatovic ◽

A. C. Fluit ◽

Karlijn Kusters ◽

Annet Toelstra ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Clonal Diversity ◽

Multidrug Resistant ◽

High Potency ◽

Molecular Surveillance ◽

Serotype O ◽

Typing Methods ◽

Automated Ribotyping ◽

Concomitant Resistance ◽

Advanced Generation

Nosocomial isolates of Pseudomonas aeruginosa andAcinetobacter spp. exhibit high rates of resistance to antibiotics and are often multidrug resistant. In a previous study (D. Milatovic, A. Fluit, S. Brisse, J. Verhoef, and F. J. Schmitz, Antimicrob. Agents Chemother. 44:1102–1107, 2000), isolates of these species that were resistant to sitafloxacin, a new advanced-generation fluoroquinolone with a high potency and a broad spectrum of antimicrobial activity, were found in high proportion in 23 European hospitals. Here, we investigate the clonal diversity of the 155 P. aeruginosa and 145Acinetobacter spp. sitafloxacin-resistant isolates from that study by automated ribotyping. Numerous ribogroups (sets of isolates with indistinguishable ribotypes) were found among isolates ofP. aeruginosa (n = 34) andAcinetobacter spp. (n = 16), but the majority of the isolates belonged to a limited number of major ribogroups. Sitafloxacin-resistant isolates (MICs > 2 mg/liter, used as a provisional breakpoint) showed increased concomitant resistance to piperacillin, piperacillin-tazobactam, ceftriaxone, ceftazidime, amikacin, gentamicin, and imipenem. The major ribogroups were repeatedly found in isolates from several European hospitals; these isolates showed higher levels of resistance to gentamicin and imipenem, and some of them appeared to correspond to previously described multidrug-resistant international clones of P. aeruginosa (serotype O:12) andAcinetobacter baumannii (clones I and II). Automated ribotyping, when used in combination with more discriminatory typing methods, may be a convenient library typing system for monitoring future epidemiological dynamics of geographically widespread multidrug-resistant bacterial clones.

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