blaOXA-181–positive Klebsiella pneumoniae, Singapore

To the Editor: Nordmann et al. (1) raised concern over the global spread of carbapenemase-producing Enterobacteriaceae. In their article, they called attention to the oxacillinase-48 (OXA-48) type carbapenemases because bacteria that produce these enzymes do not have a distinctive antimicrobial drug susceptibility profi le, and there is less awareness of this mechanism of carbapenem resistance. We report the recent isolation of bla OXA-181 –positive Klebsiella pneumoniae from 2 patients from Bangladesh who were admitted to separate hospitals in Singapore within a short period of each other. The fi rst patient was a 64-year-old man who had a recent heart attack and was transferred from a hospital in Dhaka, Bangladesh, to a hospital in Singapore for treatment for pancytopenia. He had no other history of recent travel. While in Bangladesh, the patient had Pseudomonas spp. bacteremia and had received meropenem and vancomycin. In Singapore, his antimicrobial drug treatment regimen was changed to ciprofl oxacin, linezolid, and amikacin. Blood samples obtained on the day of admission were cultured and grew a vancomycin-resistant Enterococcus spp. and a carbapenem-resistant K. pneumoniae (isolate DB53879_11). Two days after admission, when the results of his blood culture were known, the patient's antimicrobial drug treatment regimen was changed to oral linezolid (600 mg every 12 hours), intravenous tigecycline (initially 50 mg every hour but later increased to 100 mg every 12 hours), and intravenous polymyxin E (initially 3 MU/d but later increased to 3 MU every 12 hours). Blood cultured for K. pneumoniae showed positive results for 5 days after the patient was hospitalized before clearing. Isolate DB53879_11 was resistant to many antimicrobial drugs as determined by Etest (bioMérieux, Marcy l'Etoile, France) (Table). It was strongly positive for carbapenemase production as determined by use of a modifi ed Hodge test (2) and showed a negative result with the KPC + MBL Confi rm ID Kit (Rosco Diagnostica A/S, Taastrup, Denmark). Using PCR, we amplifi ed and sequenced a product identical to the complete sequence of bla OXA-181. Primers designed for known fl anking regions of bla OXA-181 (GenBank accession no. JN205800) failed to amplify any product. Like described isolates (3–5), DB53879_11 was also positive for bla OXA-1 and bla CTX-M-15 , but it also was positive for bla CMY-4. An attempt to transfer bla OXA-181 to azide-resistant Escherichia coli J53 by plate mating was unsuccessful. Two weeks after we received the specimen from the fi rst patient, we …