Unusual diversity of acquired ß-lactamases in multidrug-resistant Pseudomonas aeruginosa isolates in a Mexican hospital.

AIMS: To investigate the presence of extended spectrum and metallo ß-lactamases (MBLs) in Pseudomonas aeruginosa isolates which are resistant to imipenem and ceftazidime that were isolated in a hospital in Mexico. RESULTS: Pulsed-field gel electrophoresis (PFGE) revealed the presence of four clonal types among the 14 isolates. All these genes were found either alone or simultaneously in the P. aeruginosa strains in the following five different arrangements: ; ; ; ; and . Class 1 integrons were detected and contained the cassettes bla(GES-5) and bla(OXA-2), but not that of bla(VIM). bla(VIM) genes occurred only in the chromosome, while bla(GES-5) was located in the chromosome and in the plasmids. CONCLUSIONS: To our knowledge, this is the first description of P. aeruginosa strains simultaneously producing the VIM-2 and VIM-11 variants, and the combination of GES-5 and MBL carbapenemases, which determines a major challenge for the clinical microbiology laboratory and a remarkable epidemiological risk for the nosocomial spread of multidrug-resistant determinants.

Carbapenemasas en especies del género Pseudomonas / Carbapenemases in Pseudomonas spp

Pseudomonas aeruginosa es uno de los patógenos nosocomiales más relevantes, así como una de las principales causas de infección respiratoria crónica en pacientes con enfermedades de base, como la fibrosis quística o la enfermedad pulmonar obstructiva crónica. Su elevado nivel de resistencia intrínseca a los antibióticos, unido a su extraordinaria capacidad para desarrollar resistencias adicionales por mutaciones cromosómicas, hacen de este patógeno uno de los más difíciles de tratar. Aún es más preocupante, si cabe, la creciente detección en este microorganismo de múltiples determinantes de resistencia, frecuentemente localizados en integrones, adquiridos por transferencia horizontal a través de plásmidos o transposones. Entre estos mecanismos destacan las carbapenemasas, por el abanico de antibióticos afectados (pues en conjunto hidrolizan a prácticamente todos los betalactámicos), variedad y capacidad de dispersión. En el presente trabajo se revisa la epidemiología, el impacto y la detección de las carbapenemasas descritas hasta la fecha en el género Pseudomonas, que pertenecen principalmente a la clase B (metalo-β-lactamasas [MBL]: IMP, VIM, SPM, GIM, AIM o DIM]), pero también, en menor medida, a las clases A (GES y KPC) y D (OXA). La presencia de estas carbapenemasas transferibles no sólo es importante en P. aeruginosa, sino también en otras especies clínicamente menos relevantes dentro del género, pero que pueden actuar como reservorio y vector de dispersión de estos determinantes de resistencia. La frecuencia creciente de cepas clínicas portadoras de carbapenemasas apremia a la puesta a punto de estrategias que faciliten su detección y reduzcan la expansión de estas cepas multirresistentes y de los mecanismos transferibles implicados

Pseudomonas aeruginosa is one of the most relevant nosocomial pathogens, as well as one of the main causes of chronic respiratory infections in patients with underlying diseases such as cystic fibrosis or chronic obstructive pulmonary disease. The high intrinsic antibiotic resistance of this pathogen, together with its extraordinary capacity for acquiring additional resistances through chromosomal mutations, determines a major threat for antimicrobial therapy in hospitals worldwide. Even more concerning is the increasing detection of multiple antimicrobial resistance determinants in this microorganism, frequently located on integrons, acquired by horizontal transfer through plasmids and/or transposons. Among these mechanisms, the carbapenemases are particularly relevant, due to the wide spectrum of antibiotics affected. This work reviews the epidemiology, impact, and detection of the carbapenemases described so far in the Pseudomonas spp., that mainly include class B enzymes (metallo-β-lactamases [MBL]: IMP, VIM, SPM, GIM, AIM, or DIM), but also, to a lower extent, class A (GES y KPC) and D (OXA) beta-lactamases. The presence of transferable carbapenemases is not only important in P. aeruginosa, but also in other less clinically-relevant species of the genus, since they can act as reservoires and dispersion vectors of these resistance determinants. The growing prevalence of carbapenemase-producing clinical isolates calls for the implementation of multidisciplinary strategies to optimize the detection and minimize the dissemination of these multidrug resistant strains and the involved transferable genetic elements

[Characterization and molecular epidemiology of ESBL in Escherichia coli and Klebsiella pneumoniae in 11 Spanish hospitals (2004)]. / Caracterización y epidemiología molecular de betalactamasas de espectro extendido en Escherichia coli y Klebsiella pneumoniae en once hospitales españoles (2004).

INTRODUCTION: The epidemiological distribution of extended-spectrum beta-lactamase (ESBL) types in Escherichia coli and Klebsiella pneumoniae was evaluated in various hospitals in Spain and compared with previous studies. METHODS: A total of 11 Spanish hospitals participated in this study. Each center collected the first 15 isolates of E. coli and the first 5 of K. pneumoniae suspected of being ESBL-producers and isolated during the first quarter of 2004. Clonal study was done by PFGE after total DNA digestion with XbaI and by ERIC-PCR (Enterobacterial Repetitive Intergenic Consensus Sequences-Polymerase Chain Reaction), typing. ESBL-producers were characterized by isoelectric focusing (IEF), PCR and sequencing. RESULTS: A total of 124 strains were collected. PFGE restriction patterns showed considerable diversity among E. coli strains; 4 clusters of 2 strains each were detected. ESBL characterization of 92 E. coli strains showed a predominance of CTX-M-14 (45.7%), CTX-M-9 (20.6%) and SHV-12 (21.7%). Clonal diversity among the 32 K. pneumoniae strains was less pronounced than in E. coli; 3 clusters included 53.1% of strains. The ESBL detected in these strains included a CTX-M type in 20 cases (62.5%) (CTX-M-1, CTX-M-9, CTX-M-14 and CTX-M-15); a SHV type in 11 (34.4%) (SHV-12 and SHV-5) and TEM-4 (3.1%) in 1 case. CONCLUSION: The E. coli and K. pneumoniae strains analyzed in this period displayed a greater diversity of ESBL than has been observed in previous epidemiological studies. Analysis of clonal relationships revealed a greater diversity in E. coli than in K. pneumoniae.

Caracterización y epidemiología molecular de betalacta masas de espectro extendido en Escherichia coli y Klebsiella pneumoniae en once hospitales españoles (2004) / Characterization and molecular epidemiology of ESBL in Escherichia coli and Klebsiella pneumoniae in 11 Spanish hospitals (2004)

INTRODUCCIÓN. Se analizó la distribución epidemiológica de los diferentes tipos de betalacta masas de espectro extendido (BLEE) en Escherichia coli y Klebsiella pneumoniae en distintos hospitales de España y se comparó con estudios previos. MÉTODOS. En 11 hospitales españoles se recogieron los15 primeros aislamientos de E. coli y los 5 primeros de K. pneumoniae con sospecha de ser portadores de BLEE, aislados en el primer trimestre de 2004. Los estudios de clonalidad se realizaron mediante electroforesis en gel de campos pulsantes (PFGE) tras digestión del ADN total con XbaI y mediante ERIC-PCR (Entero bacterial Repetitive Intergenic Concensus Secuences-Polimerase Chain Reaction). Las BLEE se caracterizaron mediante isoelectro enfoque, PCR y secuenciación. RESULTADOS. Se estudiaron 124 aislamientos. El análisis de los patrones de restricción obtenidos por PFGE mostró una gran diversidad clonal entre los aislamientos de E. coli, observándose cuatro agrupaciones de dos cepas en cada una de ellas. En las 92 cepas de E. coli, la caracterización de las BLEE mostró un predominio de CTX-M-14 (45,7%),CTX-M-9 (20,6%) y SHV-12 (21,7%). En las 32 cepas de K. pneumoniae se observó una menor diversidad clonal, detectándose tres agrupaciones que incluían el 53,1%de los aislamientos. Las BLEE detectadas en estas cepas fueron del tipo CTX-M en 20 casos (62,5%) (CTX-M-1,CTX-M-9, CTX-M-14 y CTX-M-15), de tipo SHV en 11(34,4%) (SHV-12 y SHV-5) y TEM-4 (3,1%) en una. CONCLUSIÓN. Las cepas de E. coli y K. pneumoniae analizadas en ese período presentan una mayor diversidad de BLEE que la observada en estudios epidemiológicos realizados con anterioridad. Además, el análisis de la relación clonal definió una gran diversidad en E. coliy menor en K. Pneumoniae (AU)

INTRODUCTION. The epidemiological distribution ofextended-spectrum beta-lactamase (ESBL) typesin Escherichia coli and Klebsiella pneumoniae wasevaluated in various hospitals in Spain and comparedwith previous studies.METHODS. A total of 11 Spanish hospitals participatedin this study. Each center collected the first 15 isolatesof E. coli and the first 5 of K. pneumoniae suspected ofbeing ESBL-producers and isolated duringthe first quarter of 2004. Clonal study was doneby PFGE after total DNA digestion with XbaI andby ERIC-PCR (Enterobacterial Repetitive IntergenicConcensus Secuences-Polimerase Chain Reaction),typing. ESBL-producers were characterized byisoelectric focusing (IEF), PCR and sequencing.RESULTS. A total of 124 strains were collected. PFGErestriction patterns showed considerable diversityamong E. coli strains; 4 clusters of 2 strains each weredetected. ESBL characterization of 92 E. coli strainsshowed a predominance of CTX-M-14 (45.7%),CTX-M-9 (20.6%) and SHV-12 (21.7%). Clonal diversityamong the 32 K. pneumoniae strains was lesspronounced than in E. coli; 3 clusters included 53.1%of strains. The ESBL detected in these strainsincluded a CTX-M type in 20 cases (62.5%)(CTX-M-1, CTX-M-9, CTX-M-14 and CTX-M-15);a SHV type in 11 (34.4%) (SHV-12 and SHV-5)and TEM-4 (3.1%) in 1 case.CONCLUSION. The E. coli and K. pneumoniae strainsanalyzed in this period displayed a greater diversityof ESBL than has been observed in previousepidemiological studies. Analysis of clonalrelationships revealed a greater diversity in E. colithan in K. pneumoniae