Resistencia Antimicrobiana Pseudomona

Journal of Antimicrobial Chemotherapy (2007) 60, 78– 82 doi:10.1093/jac/dkm129 Advance Access publication 9 May 2007

Evolution of antimicrobial resistance among Pseudomonas aeruginosa, Acinetobacter baumannii and Klebsiella pneumoniae in Brooklyn, NY
David Landman1, Simona Bratu1, Sandeep Kochar1, Monica Panwar1, Manoj Trehan1, Mehmet Doymaz2 and John Quale1*1

State University of New York—Downstate, Brooklyn, NY, USA; 2Beth Israel Medical Center, New York, NY, USA
Downloaded from http://jac.oxfordjournals.org by on June 1, 2010 Received 16 February 2007; returned 22 March 2007; revised 2 April 2007; accepted 5 April 2007

Objectives: To document resistance patterns of three important nosocomial pathogens,Pseudomonas aeruginosa, Acinetobacter baumannii and Klebsiella pneumoniae, present in hospitals in Brooklyn, NY. Methods: Susceptibility profiles of pathogens gathered during a surveillance study in 2006 were analysed and compared with similar surveys performed in 1999 and 2001. MICs were determined according to CLSI standards, and selected isolates were screened by PCRfor the presence of VIM, IMP and KPC b-lactamases. Results: For P. aeruginosa, susceptibility to most antimicrobials fell in 2001 and then reached a plateau. However, there was a progressive decrease in the number of patients with P. aeruginosa during the three surveys. While the total number of isolates of A. baumannii remained steady, there was a progressivedecrease in susceptibility to most classes of antimicrobial agents, and approximately one-third had combined resistance to carbapenems, fluoroquinolones and aminoglycosides. There was a noticeable rise in the number of isolates of K. pneumoniae over the surveillance periods, suggesting that this has become the predominant pathogen in many medical centres. Over one-thirdof K. pneumoniae collected in 2006 carried the carbapenemase KPC, and 22% were resistant to all three classes of antimicrobial agents. Conclusions: Hospitals in our region have been beset with antimicrobial-resistant Gram-negative bacteria. K. pneumoniae has rapidly emerged as the most common multidrug-resistant pathogen. Improved therapeutic agents and methods ofdetection are needed to reduce transmission of these bacteria. Keywords: P. aeruginosa, A. baumannii, K. pneumoniae

Introduction
Nosocomial infections due to multidrug-resistant bacterial pathogens have been associated with increased hospital expenditures and poorer clinical outcomes. Three multidrug-resistant Gram-negative bacteria have emerged in many medicalcentres as particularly troublesome pathogens. First, Pseudomonas aeruginosa is a frequent cause of respiratory, surgical site and urinary tract infections in patients from intensive care areas.1 Several studies have documented increasing resistance rates in P. aeruginosa to fluoroquinolones, cephalosporins and carbapenems, particularly among ICU isolates.2 – 4 Inthese reports,

carbapenem and ciprofloxacin resistance has been noted in 20% and 30% of the isolates, respectively. Second, Acinetobacter baumannii is being recognized as an emerging pathogen in many medical facilities. According to NNIS data, the proportion of infections due to Acinetobacter spp. has increased, and accounts for 7% of ICU-related pneumonias.1In several wide-scale surveillance studies, carbapenem, cephalosporin and ciprofloxacin resistance rates have approached 20%, 50% and 50%, respectively.1,3,4 Infections due to multidrug-resistant Acinetobacter baumannii have been associated with increased length of hospital and ICU stays, and a polymyxin is often the antimicrobial agent of last resort....