Twenty Klebsiella pneumoniae isolates producing OXA-48 were collected from April 2009 to September 2010. Strains were clonally related and coproduced a CTX-M-15 β-lactamase. A conjugative plasmid of circa 70 kb carrying bla _OXA-48 was identified. Eleven isolates showed low-level resistance to carbapenems, whereas nine showed high-level resistance. Decreased expression of OmpK36 was related to high-level resistance to carbapenems. The isolates belonged to sequence type 101 (ST101). This is the first outbreak caused by an OXA-48-producing K. pneumoniae strain in Spain.

Enteroaggregative Escherichia coli (EAEC) and enterotoxigenic E. coli (ETEC) are among the most frequent microorganisms causing traveller's diarrhoea. The aim of this study was to investigate the evolution of antimicrobial resistance in EAEC and ETEC causing diarrhoea in patients who had travelled to different developing countries, comparing two periods of time, 1994–97 and 2001–04. Overall, 134 EAEC and 190 ETEC clinical isolates were studied. The MICs of ampicillin, chloramphenicol, nalidixic acid, tetracycline, trimethoprim/sulfamethoxazole, ciprofloxacin and amoxicillin/clavulanic acid were determined by the Etest method. Detection of mutations in the quinolone-resistance determining region of the gyrA and parC genes was performed by PCR and DNA sequencing. When antimicrobial resistance in EAEC and ETEC isolates was compared between the two periods of time, a statistically significant increase in resistance (P < 0.01) was observed in EAEC for chloramphenicol and amoxicillin/clavulanic acid, whereas in ETEC it was for trimethoprim/sulfamethoxazole, nalidixic acid, ciprofloxacin and amoxicillin/clavulanic acid. Mutations in the gyrA gene were found in all nalidixic acid-resistant isolates, whereas mutation(s) in both gyrA and parC genes were found in the ciprofloxacin-resistant isolates. The high percentage of resistance to quinolones in ETEC and EAEC isolated from travellers to North Africa and India is a matter for concern. These agents should therefore be used with caution in patients with traveller's diarrhoea returning from these geographical areas.

Evidence supporting the combination of aminoglycosides with β-lactams for Gram-negative bacteremia is inconclusive. We have explored the influence on survival of empirical therapy with a β-lactam alone versus that with a β-lactam-aminoglycoside combination by retrospectively analyzing a series of bacteremic episodes due to aerobic or facultative Gram-negative microorganisms treated with single or combination therapy. The outcome variable was a 30-day mortality. Prognostic factors were selected by regression logistic analysis. A total of 4,863 episodes were assessed, of which 678 (14%) received combination therapy and 467 (10%) were fatal. Factors independently associated with mortality included age greater than 65 (odds ratio [OR], 2; 95% confidence interval [CI], 1.6 to 2.6), hospital acquisition (OR, 1.5; 95% CI, 1.2 to 1.9), a rapidly or ultimately fatal underlying disease (OR, 2.5; 95% CI, 2 to 3.2), cirrhosis (OR, 1.9; 95% CI, 1.4 to 2.6), prior corticosteroids (OR, 1.5; 95% CI, 1.1 to 2), shock on presentation (OR, 8.8; 95% CI, 7 to 11), pneumonia (OR, 2.8; 95% CI, 1.9 to 4), and inappropriate empirical therapy (OR, 1.8; 95% CI, 1.3 to 2.5). Subgroup analysis revealed that combination therapy was an independent protective factor in episodes presenting shock (OR, 0.6; 95% CI, 0.4 to 0.9) or neutropenia (OR, 0.5; 95% CI, 0.3 to 0.9). Combination therapy improved the appropriateness of empirical therapy in episodes due to extended-spectrum β-lactamase (ESBL)- or AmpC-producing Enterobacteriaceae and Pseudomonas aeruginosa . In patients with Gram-negative bacteremia, we could not find an overall association between empirical β-lactam-aminoglycoside combination therapy and prognosis. However, a survival advantage cannot be discarded for episodes presenting shock or neutropenia, hence in these situations the use of combination therapy may still be justified. Combination therapy also should be considered for patients at risk of being infected with resistant organisms, if only to increase the appropriateness of empirical therapy.

A carbapenem-resistant Escherichia coli strain (DVR22) was recovered from a stool specimen from a patient with traveler's diarrhea who had traveled to India. Molecular screening led to the first identification of NDM-1 in Spain. The bla _NDM-1 gene was located in a conjugative plasmid of ca. 300 kb that also contained the bla _CTX-M-15 , bla _TEM-1 , Δ bla _DHA-1 , and armA genes. In addition, bla _NDM-1 was preceded by an IS Aba125 insertion element only found in Acinetobacter spp.

A carbapenem-resistant Escherichia coli isolate (sequence type 448 [ST448]) was recovered from a urine culture of a female patient with no recent record of traveling. PCR screening identified the presence of bla _NDM-5 , bla _TEM-1 , bla _OXA-1 , bla _CMY-42 , and rmtB. bla _NDM-5 was carried in a conjugative IncFII-type plasmid (90 kb) together with bla _TEM-1 and rmtB . The genetic environment of bla _NDM-5 showed a structure similar to those of pMC-NDM and pGUE-NDM, identified in Poland and France in E. coli of African and Indian origin, respectively.