Chromosome-Encoded AmpC and CTX-M Extended-Spectrum β-Lactamases in Clinical Isolates of Proteus mirabilis from Korea

Abstract

Among 222 Proteus mirabilis clinical isolates collected from 17 hospitals in Korea in 2008, 28 (12.6%) and 8 (3.6%) isolates exhibited extended-spectrum ␤-lactamase (ESBL) and AmpC phenotypes, respectively. The most common type of ESBL gene identified by PCR and sequencing experiments was bla CTX-M-14a (n ‫؍‬ 12). The bla CTX-M-90 (n ‫؍‬ 4), bla CTX-M-15 (n ‫؍‬ 3), bla CTX-M-12 (n ‫؍‬ 3), bla CTX-M-2 (n ‫؍‬ 2), bla CTX-M-14b (n ‫؍‬ 1), bla TEM-52 (n ‫؍‬ 5), and bla SHV-12 (n ‫؍‬ 1) genes were also detected. Eight isolates carried an AmpC ␤-lactamase gene, such as bla CMY-2 (n ‫؍‬ 6) or bla DHA-1 (n ‫؍‬ 2). All bla genes encoding CTX-M-1-and CTX-M-9-type enzymes and all bla CMY-2 genes were preceded by ISEcp1-like elements. The bla CTX-M-2 gene found in two isolates was located on a complex class 1 integron. The bla DHA-1 gene was preceded by a transcriptional regulator gene and was followed by phage shock protein genes. The bla CTX-M genes were located on the chromosome in 21 isolates. A plasmid location for the bla CTX-M gene was found in only four isolates: the bla CTX-M-14a gene was located on ϳ150-kbp IncA/C plasmids in three isolates and on a ϳ50-kbp IncN plasmid in one isolate. The bla TEM-52 gene was located on ϳ50-kbp IncN plasmids in all five isolates. The AmpC ␤-lactamase genes were located on the chromosome in seven of eight isolates; one isolate carried the bla CMY-2 gene on a ϳ150-kbp IncA/C plasmid. Our results show that a chromosomal location of CTX-M ESBL and AmpC ␤-lactamase genes in P. mirabilis is no longer an unusual phenomenon in hospital environments.

Strain Diversity of CTX-M-Producing Enterobacteriaceae in Individual Pigs: Insights into the Dynamics of Shedding during the Production Cycle

“…The molecular epidemiology of ESBL-encoding genes in P. mirabilis isolated from humans varies widely between geographical regions. TEM types, especially TEM-52 and TEM-92, dominate in France and Italy (44,45), while CTX-M types are common in Israel (CTX-M-2), Poland (CTX-M-3), Japan (CTX-M-2), South Korea (CTX-M-14), and Argentina (CTX-M-2) (41,42,(46)(47)(48). Providencia species producing ESBL types other than CTX-M-2 have only been reported on a few occasions (49).…”

Chromosomal Integration and Location on IncT Plasmids of the bla CTX-M-2 Gene in Proteus mirabilis Clinical Isolates

“…Although chromosomal integration of bla CTX-M and other genes encoding extended-spectrum ␤-lactamases is regarded as a relatively uncommon event (11,12), several studies have suggested that those events could be more common in P. mirabilis (2,8,9,19,28,32). Of 28 CTX-M-producing P. mirabilis clinical isolates collected in Korea, 21 carried bla CTX-M on the chromosome (28).…”

Characterization of CTX-M-140, a Variant of CTX-M-14 Extended-Spectrum β-Lactamase with Decreased Cephalosporin Hydrolytic Activity, from Cephalosporin-Resistant Proteus mirabilis

“…1). Chromo- somally located bla CTX-M genes, including bla CTX-M-2 , bla CTX-M-12 , bla CTX-M-14 , bla CTX-M-15 , bla CTX-M-41 , and bla CTX-M-90 , have been found in several countries (9,11,20).…”