CTX-M β-Lactamase–producing Klebsiella pneumoniae in Suburban New York City, New York, USA - Vol. 19 No. 11 - November 2013 - Emerging Infectious Disease journal - CDC
Volume 19, Number 11—November 2013
CTX-M β-Lactamase–producing Klebsiella pneumoniae in Suburban New York City, New York, USA
CTX-M enzymes are a group of class A extended-spectrum β-lactamases (ESBLs) that are rapidly spreading among Enterobacteriaceae worldwide (1). Since the initial isolation of CTX-M-1 from a European patient in the late 1980s (2), > 130 CTX-M allelic variants have been described (http://www.lahey.org/Studies/other.asp#table1). These CTX-M variants have been divided into 5 major phylogenetic groups, CTX-M-1, CTX-M-2, CTX-M-8, CTX-M-9, or CTX-M-25 on the basis of their amino acid sequences (1,2).
AbstractCTX-M extended-spectrum β-lactamase (ESBL)–producing Klebsiella pneumoniae isolates are infrequently reported in the United States. In this study, we analyzed nonduplicate ESBL-producing K. pneumoniae and Escherichia coli clinical isolates collected during 2005–2012 at a tertiary care medical center in suburban New York City, USA, for the presence of blaCTX-M, blaSHV, blaTEM, and blaKPC genes. Despite a high prevalence of blaCTX-M genes in ESBL-producing E. coli since 2005, blaCTX-M genes were not detected in K. pneumoniae until 2009. The prevalence of CTX-M–producing K. pneumoniae increased significantly over time from 1.7% during 2005–2009 to 26.4% during 2010–2012 (p< 0.0001). CTX-M-15 was the dominant CTX-M genotype. Pulsed-field gel electrophoresis and multilocus sequence typing revealed high genetic heterogeneities in CTX-M–producing K. pneumoniae isolates. This study demonstrates the recent emergence and polyclonal spread of multidrug resistant CTX-M–producing K. pneumoniae isolates among patients in a hospital setting in the United States.
During the past decade, CTX-M enzymes have become the most prevalent ESBL enzymes in clinical Enterobacteriaceae isolates, especially in ESBL-producing Escherichia coli in Europe, Asia, and South America (1,3). By contrast, SHV- and TEM-type ESBL enzymes are primarily found in ESBL-producing K. pneumoniae and E. coli clinical isolates in North America (3). In the United States, CTX-M–like ESBL-producing Enterobacteriaceae was first reported in 2003, when CTX-M enzymes were detected in 9 E. coli clinical isolates from 5 US states (4). The spread of CTX-M type ESBL in Enterobacteriaceae, however, was not appreciated until 2007 when a Texas study showed a high prevalence of CTX-M ESBL in E. coli clinical isolates recovered during 2000–2005 (5). Since then, CTX-M–producing E. coli isolates have been documented in dispersed US geographic regions (3,6,7). CTX-M enzymes are now the predominant ESBL type in E. coli clinical isolates in Texas (5), Pennsylvania (6), Illinois (8), and New York (9,10).