BackgroundHealthcare-associated infections caused by Klebsiella pneumoniae isolates are increasing and few effective antibiotics are currently available to treat patients. We observed decreased carbapenem susceptibility among K. pneumoniae isolated from patients at a tertiary private hospital that showed a phenotype compatible with carbapenemase production although this group of enzymes was not detected in any sample. The aim of this study was to describe the epidemiology and clinical outcomes associated with carbapenem-resistant K. pneumoniae and to determine the antimicrobial resistance mechanisms.MethodsRisk factors associated with carbapenem-resistant K. pneumoniae infections were investigated by a matched case–control study from January 2006 through August 2008. A cohort study was also performed to evaluate the association between carbapenem resistance and in-hospital mortality. Bacterial identification and antimicrobial susceptibility were determined by Vitek 2 and Etest. Carbapenemase activity was detected using spectrophotometric assays. Production of beta-lactamases and alterations in genes encoding K. pneumoniae outer membrane proteins, OmpK35 and OmpK36, were analyzed by PCR and DNA sequencing, as well as SDS-Page. Genetic relatedness of carbapenem resistant isolates was evaluated by Pulsed Field Gel Electrophoresis.ResultsSixty patients were included (20 cases and 40 controls) in the study. Mortality was higher for patients with carbapenem-resistant K. pneumoniae infections compared with those with carbapenem-susceptible K. pneumoniae (50.0% vs 25.7%). The length of central venous catheter use was independently associated with carbapenem resistance in the multivariable analysis. All strains, except one, carried blaCTX-M-2, an extended-spectrum betalactamase gene. In addition, a single isolate also possessed blaGES-1. Genes encoding plasmid-mediated AmpC beta-lactamases or carbapenemases (KPC, metallo-betalactamases or OXA-carbapenemases) were not detected.ConclusionsThe K. pneumoniae multidrug-resistant organisms were associated with significant mortality. The mechanisms associated with decreased K. pneumoniae carbapenem susceptibility were likely due to the presence of cephalosporinases coupled with porin alterations, which resulted from the presence of the insertion sequences in the outer membrane encoding genes.

Background: Complicated intra-abdominal infections (cIAI) remain challenging to treat because of their polymicrobial etiology including multi-drug resistant bacteria. The efficacy and safety of tigecycline, an expanded broad-spectrum glycylcycline antibiotic, was compared with imipenem/cilastatin (IMI/CIS) in patients with cIAI.

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Tigecycline (TGC) has demonstrated clinical efficacy and safety, in comparison with imipenem/cilastatin in phase 3 clinical trials, for complicated intra-abdominal infection (cIAI). The present study comprised a multicentre, open-label, randomized study of TGC vs. ceftriaxone plus metronidazole (CTX/MET) for the treatment of patients with cIAI. Eligible subjects were randomized (1:1) to receive either an initial dose of TGC (100 mg) followed by 50 mg every 12 h or CTX (2 g once daily) plus MET (1-2 g daily), for 4-14 days. The primary endpoint was the clinical response in the clinically evaluable (CE) population at the test of cure (TOC) assessment. Of 473 randomized subjects, 376 were CE. Among these, clinical cure rates were 70.4% (133/189) with TGC vs. 74.3% (139/187) with CTX/MET (95% CI -13.1 to 5.1; p 0.009 for non-inferiority). Clinical cure rates for subjects with Acute Physiological and Chronic Health Evaluation II scores > or =10 were 56.8% (21/37) with TGC vs. 58.3% (21/36) with CTX/MET. The microbiologic response was similar between the two treatment arms, with microbiological eradication at TOC achieved in 68.1% (94/138) of TGC-treated subjects and 71.5% (98/137) of CTX/MET-treated subjects. (The most frequently reported adverse events (AEs) for both treatment arms were nausea (TGC, 38.6% vs CTX/MET, 27.7%) and vomiting (TGC, 23.3% vs CTX/MET, 17.7%). Overall discontinuation rates as a result of an AE were 8.9% and 4.8% in TGC- and comparator-treated subjects, respectively. The results obtained in the present study demonstrate that TGC monotherapy is non-inferior to a combination regimen of CTX/MET with respect to treating subjects with cIAI.

An outbreak of bacteraemia in a haemodialysis unit where 65 episodes of infection involved 35 outpatients is reported. Burkholderia cepacia complex was the agent most frequently recovered from blood. Thirty-three environmental and clinical isolates of B. cepacia complex were characterized by whole-cell protein electrophoresis and recA-RFLP profile. Fourteen isolates were genomovar I and 16 isolates were not classifiable by their recA-RFLP pattern. Ribotyping, random amplification of polymorphic DNA (RAPD) and integron profile were used to explore the clonality of the isolates, and revealed multiple strain genotypes. Four ribotypes and RAPD types and three integron patterns were identified. The water supply was identified as the source of the outbreak, and inappropriate cleaning and a leak in the reverse osmosis tubing connection were the probable causes of contamination. B. cepacia complex was still recovered from blood of patients even after apparently adequate measures were taken and water quality standards were met, suggesting that higher standards for water quality should be adopted in haemodialysis units. The genomovars recovered here were distinct from those commonly reported for cystic fibrosis isolates.