Diversity of carbapenemase producing P. aeruginosa clones suggests serious implications on clinical outcomes and resistance dissemination

Monday, 18 August 2014
Exhibit hall (Dena'ina Center)
Astrid V Cienfuegos, MS , University of Antioquia, Medellin, Colombia
Johanna M Vanegas, BS , University of Antioquia, Medellin, Colombia
Ana M Ocampo, BS , University of Antioquia, Medellin, Colombia
Carlos A Vargas, BS , University of Antioquia, Medellin, Colombia
Lucelly Lopez , Grupo MICROBA, Escuela de Microbiología, Universidad de Antioquia UdeA, Medellin, Colombia
Helena del Corral, PhD , University of Antioquia, Medellin, Colombia
Judy N Jiménez, PhD , University of Antioquia, Medellin, Colombia
INTRODUCTION:  Pseudomonas aeruginosa has become a serious health threat worldwide due to its high rates of multidrug resistance. However, dissemination of resistance is difficult to assess because evidence from surveillance systems is limited by unreliable phenotypic susceptibility tests. Considering the importance of strengthening surveillance systems to control antibiotic resistance, this study aims to describe the molecular epidemiology of carbapenem-resistant Pseudomonas aeruginosa(CRP) infections and assess impact of these infections on clinical outcomes in hospitals in Medellín-Colombia. 

METHODS:  A prospective cohort of patients infected with CRP was enrolled in five tertiary-care level hospitals from Medellín between June-2012 and May-2013. All subjects were followed until clinical outcome. Clinical and microbiological information was retrieved from medical records. Carbapenemases were detected by PCR and strain typing by PFGE. Bivariate analyses were done using X2,Fisher’s exact test, risk ratios (RR). 

RESULTS:  During the study period 146 patients were included. Carbapenemases blaVIM and blaKPC were detected in 15.1% and 7.5% isolates, respectively. Carbapenemase (C) and non-carbapenemase (NC) producing isolates were different regarding predominant types of infections (p=0.034). MDR (resistance to ≥3 antibiotic families) was higher in C (77.4%) than in NC (27%) isolates (p<0.001). Mortality was higher in infections caused by C than NC (RR=1,47, IC95%: 0.82-2.64). A pseudo outbreak of CRP harboring blaKPCwas detected between August-2012 and January-2013 in four hospitals but PFGE revealed that isolates were genetically different. 

CONCLUSIONS:  In Medellín, the presence of C isolates with diverse genetic backgrounds has emerged with relevant implications in patient clinical outcomes. This situation points to antibiotic selective pressure as a driving force for resistance emergence and a high potential of carbapenemase dissemination in P. aeruginosa. Incorporating molecular epidemiology to surveillance activities should become the mainstay in order to improve understanding of emergence of resistant clones and effectively control antibiotic resistance in Colombia.

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