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.

[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.