In our experience, linezolid has been a valid alternative drug in the management of multidrug-resistant tuberculosis. The prolonged use of linezolid is frequently associated with toxicity, mainly anaemia and peripheral neuropathy, that requires special management.

Background. We report the emergence and spread of metallo-b-lactamases (MBLs) among enterobacterial isolates at Ramó n y Cajal University Hospital (Madrid, Spain).Methods and results. During the period from March 2005 through September 2006, 25 patients (52% of whom were in the intensive care unit) were infected and/or colonized with single or different MBL-producing Enterobacteriaceae isolates (Klebsiella pneumoniae, 14 patients; Enterobacter cloacae, 12 patients; Escherichia coli, 1 patient; and/or Klebsiella oxytoca, 1 patient). Clonal analysis (XbaI pulsed-field gel electrophoresis) revealed that all K. pneumoniae isolates belonged to the same clone, but 6 patterns were found among the E. cloacae isolates. Carbapenems were affected to different degrees (minimum inhibitory concentration, р1 to 18 mg/mL), as were aminoglycosides and ciprofloxacin. The bla VIM-1 MBL gene was present in all isolates; in addition, the bla SHV-12 extended-spectrum b-lactamase gene was detected in K. pneumoniae and E. coli isolates. The bla VIM-1 gene was detected within a 4.0-kb class 1 integron (bla VIM-1 -aacA4-dfrII-aadA1-catB2) in K. pneumoniae and E. coli and in a 2.5-kb class 1 integron (bla VIM-1 -aacA4-aadA1) in E. cloacae and K. oxytoca isolates. The bla VIM-1 gene was transferable (filter-mating) in 14 of 14 K. pneumoniae isolates, 4 of 11 E. cloacae isolates, and 1 of 1 E. coli isolate. A 60-kb plasmid belonging to the IncI1 group was detected in the epidemic VIM-1-K. pneumoniae clone. Plasmids of 300-or 435-kb belonging to IncH12 group were found among E. cloacae isolates.Conclusions. K. pneumoniae-MBL monoclonal epidemics coexisted with E. cloacae-MBL multiclonal epidemics in our hospital. The spread of the bla VIM-1 gene among Enterobacteriaceae was driven by clonal spread associated with intergeneric plasmid transfer with different class I integron platforms. Such complex epidemiology might anticipate endemicity and should be considered for the design of containment epidemiology strategies.

ALT appears as an effective conservative treatment in the management of CRB associated with long-term intravascular devices (84% in the present series), especially in infections caused by coagulase-negative staphylococci.

Rapid identification of patients who are colonized with carbapenemase-producing organisms (CPO) is included in multiple national guidelines for containment of these organisms. In a multisite study, we evaluated the performance of the Cepheid Xpert Carba-R assay, a qualitative diagnostic test that was designed for the rapid detection and differentiation of the blaKPC, blaNDM, blaVIM, blaOXA-48, and blaIMP-1 genes from rectal swab specimens. A double rectal swab set was collected from 383 patients admitted at four institutions (2 in the United States, 1 in the United Kingdom, 1 in Spain). One swab was used for reference culture (MacConkey broth containing 1 mg/liter of meropenem and subcultured to a MacConkey agar plate with a 10-μg meropenem disk) and for sequencing of DNA obtained from carbapenem-nonsusceptible isolates for carbapenemase identification. The other swab was used for the Xpert Carba-R assay. In addition to the clinical rectal swabs, 250 contrived specimens (108 well-characterized CPO and 142 negative controls spiked onto negative rectal swabs) were tested. Overall, 149/633 (23.5%) samples were positive by the Xpert Carba-R assay. In 6 samples, multiple targets were detected (4 VIM/OXA-48, 1 IMP-1/NDM, and 1 NDM/KPC). The Xpert Carba-R assay detected 155 targets (26 IMP-1, 30 VIM, 27 NDM, 33 KPC, 39 OXA-48) within a time range of 32 to 48 min. The sensitivity, specificity, and positive and negative predictive values of the Xpert Carba-R assay compared to those of the reference culture and sequencing results were 96.6% (95% confidence interval [CI], 92.2% to 98.9%), 98.6% (95% CI, 97.1% to 99.4%), 95.3%, and 99.0%, respectively. The Cepheid Xpert Carba-R assay is an accurate and rapid test to identify rectal colonization with CPO, which can guide infection control programs to limit the spread of these organisms.

The emergence of bla VIM-1 within four different genetic platforms from distinct Enterobacteriaceae and Pseudomonas aeruginosa isolates in an area with a low prevalence of metallo-␤-lactamase producers is reported. Forty-three VIM-1-producing isolates (including 19 Enterobacter cloacae, 2 Escherichia coli, and 2 P. aeruginosa isolates, 18 Klebsiella pneumoniae isolate, and 2 Klebsiella oxytoca isolate) recovered from 2005 to 2007 and corresponding to 15 pulsed-field gel electrophoresis types were studied. The Enterobacteriaceae isolates corresponded to a hospital outbreak, and the P. aeruginosa isolates were sporadically recovered. The genetic context of the integrons carrying bla VIM-1 (arbitrarily designated types A, B, C, and D) was characterized by PCR mapping based on known Tn402 and mercury transposons and further sequencing. Among Enterobacteriaceae isolates, bla VIM-1 was part of integrons located either in an In2-Tn402 element linked to Tn21 (type A; In110-bla VIM-1 -aacA4-aadA1) or in a Tn402 transposon lacking the whole tni module [type B; In113-bla VIM-1 -aacA4-dhfrII (also called dfrB1)-aadA1-catB2] and the transposon was associated with an IncHI2 or IncI1 plasmid, respectively. Among P. aeruginosa isolates, bla VIM-1 was part of a new gene cassette array located in a defective Tn402 transposon carrying either tniB⌬3 and tniA (type C; bla VIM-1 -aadA1) or tniC and ⌬tniQ (type D; bla VIM-1 -aadB), and both Tn402 variants were associated with conjugative plasmids of 30 kb. The dissemination of bla VIM-1 was associated with different genetic structures and bacterial hosts, depicting a complex emergence and evolutionary network scenario in our facility, Ramón y Cajal University Hospital, Madrid, Spain. Knowledge of the complex epidemiology of bla VIM-1 is necessary to control this emerging threat.