OXA-163, an OXA-48-Related Class D β-Lactamase with Extended Activity Toward Expanded-Spectrum Cephalosporins

Abstract

Two bla OXA-48 -like-positive isolates (Klebsiella pneumoniae and Enterobacter cloacae) were recovered in Argentina in 2008 as part of a large-scale survey focused on multidrug resistance in Enterobacteriaceae. In both cases, sequencing identified ␤-lactamase OXA-163, differing from OXA-48 by a single amino substitution and a 4-amino-acid deletion. OXA-163 hydrolyzed penicillins, ceftazidime, and cefotaxime, whereas OXA-48 did not. However, OXA-163 had a much lower ability to hydrolyze carbapenems than OXA-48, therefore barely being considered a carbapenemase. In both isolates, the bla OXA-163 gene was located on plasmids that differed in structure and size. However, a detailed genetic analysis revealed a similar genetic context in those isolates, with the bla OXA-163 gene being bracketed by novel transposase genes, making this genetic environment different from that reported for the bla OXA-48 gene. This study identified the first class D ␤-lactamase compromising both extended-spectrum cephalosporin and carbapenem activities.Class D ␤-lactamases or oxacillinases are widely distributed among clinically relevant Gram-negative species (31). A high degree of diversity is observed at the biochemical and genetic levels among these enzymes exhibiting a narrow or broad spectrum of hydrolysis toward ␤-lactams (31). Genes encoding oxacillinases are usually embedded as gene cassettes into class 1 integrons, but other potentially mobile genetic vehicles have also been described, including insertion sequences (ISs) (31). Among class D ␤-lactamases, some enzymes confer the ability to hydrolyze carbapenems and have mostly been identified in Acinetobacter spp. (32) but rarely in Enterobacteriaceae (33). The carbapenem-hydrolyzing class D ␤-lactamase (CHDL) OXA-48 was initially identified in Turkey, first in Klebsiella pneumoniae and then in other enterobacterial species (1,5,6,15,23,29). OXA-48 exhibits a hydrolysis profile that includes penicillins and carbapenems and that spares cephalosporins (29). Lately, the bla OXA-48 gene has been identified in different countries, such as Lebanon, Tunisia, Israel, Belgium, and France and recently in Senegal and Morocco (3,[9][10][11]14,19,[20][21][22]34). Several isolates producing OXA-48 have been involved as a source of nosocomial outbreaks (5, 11). The bla OXA-48 gene has often been identified on a 70-kb plasmid featured by the replication protein RepP (6). The bla gene is usually identified in association with two IS1999 insertion sequences, forming the composite transposon Tn1999 (2). Here we report an OXA-48-related CHDL that possesses very peculiar hydrolytic properties and whose gene is associated with novel genetic structures. MATERIALS AND METHODSBacterial strains. Identification of K. pneumoniae (isolate Kp6299) and Enterobacter cloacae 2185 (isolate Enc2185) was performed by using the API 20E system (bioMérieux, Marcy l'Étoile, France). Escherichia coli TOP10 was used as the host strain for cloning, and E. coli J53 (resistant to azide) was used as the host for conjugation ...

Rapidec Carba NP Test for Rapid Detection of Carbapenemase Producers

“…isolate gave a negative result, which is in accordance with the fact that this OXA-48 variant is known to lack significant carbapenemase activity (28).…”

OXA-163-Producing Klebsiella pneumoniae in Cairo, Egypt, in 2009 and 2010

“…First, the detection of OXA-163 outside the continent where it has been firstly identified was unexpected. This finding seems to stand against the hypothesis of OXA-163 as the equivalent in South America of OXA-48 in the Mediterranean area (15). The two patients had no history of travel abroad.…”

“…Moreover, it is of special interest that OXA-163 has been identified in Egypt, a country of North Africa, a geographical area where OXA-48-producing Gram negatives are considered endemic (6, 9, 10). Third, both strains had much higher MICs for carbapenems than those reported by Poirel et al (15). Studies suggest that outer membrane permeability defects coupled with ESBL production can confer resistance to carbapenems (5,7,9).…”

“…As previously reported about OXA-163-producing strains in Argentina, because of its unique hydrolysis ability mimicking a class A ESBL, OXA-163 could be able to spread unrecognized as a carbapenemase (15). Surveillance of emergence and dissemination of enterobacteria with complex carbapenem resistance mechanisms is a serious public health problem where the costs can be unaffordable, such as low-resource countries.…”

Evaluation of the Blue-Carba Test for Rapid Detection of Carbapenemases in Gram-Negative Bacilli

“…The results observed in this work could be linked to the low hydrolytic profile of OXA-163 producers, although there is still an open debate on its role as a carbapenemase. Whereas in vitro kinetic assays showed weak carbapenemase activity (11), in vivo data have suggested that OXA-163 per se could cause carbapenem treatment failure or favor the intrapatient selection of new OXA variants (12,13). a A color change from blue or green (control tube) to green/yellow or yellow (reaction tube), respectively, was interpreted as a positive result; when both tubes (control and reaction) remained either blue or green, the test was interpreted as negative.…”