Emergence of Klebsiella pneumoniae carbapenemase-producing bacteria.

Klebsiella pneumoniae carbapenemase (KPC)-producing bacteria are a group of emerging highly drug-resistant Gram-negative bacilli causing infections associated with significant morbidity and mortality. Once confined to outbreaks in the northeastern United States (US), they have spread throughout the US and most of the world. KPCs are an important mechanism of resistance for an increasingly wide range of Gram-negative bacteria and are no longer limited to K pneumoniae. KPC-producing bacteria are often misidentified by routine microbiological susceptibility testing and incorrectly reported as sensitive to carbapenems; however, resistance to the carbapenem antibiotic ertapenem is common and a better indicator of the presence of KPCs. Carbapenem antibiotics are generally not effective against KPC-producing organisms. The best therapeutic approach to KPC-producing organisms has yet to be defined; however, common treatments based on in vitro susceptibility testing are the polymyxins, tigecycline, and less frequently, aminoglycoside antibiotics. The purpose of this review is to identify the various challenges that KPC-producing bacteria present to clinicians. These include the need for special techniques for microbiological detection, the potential for nosocomial transmission, and therapeutic challenges related to limited, relatively unproven antimicrobial treatment options.

Single center experience of a vancomycin resistant enterococcal endocarditis cohort.

OBJECTIVES: Vancomycin resistant enterococcus (VRE) infective endocarditis (IE) is an increasing nosocomial problem. We describe the clinical management and outcomes of a cohort of patients with VRE IE at a tertiary endocarditis referral center. METHODS: Retrospective review of all proven cases of VRE IE, from July 2000 through January 2008 was performed. Demographics, comorbidities and therapeutic details were collected and analyzed to assess for risk factors and clinical outcomes. RESULTS: Fifty cases of VRE IE were identified: 26 (52%) were Enterococcus faecium and 24 were Enterococcus faecalis. Vancomycin resistant E. faecalis IE was associated with the presence of a central venous line, liver transplantation, and mitral valve infection while VR E. faecium IE was significantly associated with tricuspid valve infection (p=0.03). The median duration of bacteremia was 14 days for E. faecium and 4 days for E. faecalis, respectively (p=0.002). Factors associated with mortality on bivariate analysis were hemodialysis via a catheter with VR E. faecium (OR=11.7. CI 1.1-122, p=0.02) and liver transplantation with both species. Combination antimicrobial therapy (OR=0.5 CI=0.06-3.2, p=0.1) and valve surgery (OR 1.3 CI 0.8-20, p=0.02) trended toward improved survival with E. faecalis on bivariate analysis. On multivariate analysis, none of the associations were significant. CONCLUSIONS: Hemodialysis and liver transplantation were factors associated with acquisition of VRE IE. There was a higher mortality and prolonged bacteremia with VR E. faecium IE than VR E. faecalis IE. Although not significant, combination antimicrobial therapy and surgical intervention trended toward improved survival.