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 profile, and there is less awareness of this mechanism of carbapenem resistance. We report the recent isolation of blaOXA-181–positive Klebsiella pneumoniae from 2 patients from Bangladesh who were admitted to separate hospitals in Singapore within a short period of each other.

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)(4)(5), DB53879_11 was also positive for bla OXA-1 and bla CTX-M-15 , but it also was positive for bla  . An attempt to transfer bla OXA-181 to azideresistant Escherichia coli J53 by plate mating was unsuccessful.
Two weeks after we received the specimen from the fi rst patient, we were referred 2 carbapenem-resistant K. pneumoniae strains isolated from sputum (isolate DX1083_11) and blood (isolate BL21479_11) from a 30 year-old man admitted to another hospital in Singapore. He had been treated in the same hospital in Dhaka as the fi rst patient for multiorgan failure secondary to dengue shock syndrome.
Antimicrobial drug susceptibility phenotypes and resistance gene complements for DX1083_11 and BL21479_11were similar to those for the isolate from the fi rst patient. The second patient received intravenous tigecycline, polymyxin B, and meropenem.
All 3 isolates were identical when tested by random amplifi cation of polymorphic DNA (6) and by pulsed-fi eld gel electrophoresis after restriction endonuclease digestion of chromosomal DNA with SpeI. Multilocus sequence typing showed that DX1083_11 belonged to sequence type 14 (www.pasteur.fr/recherche/ genopole/PF8/mlst/Kpneumoniae. html). This sequence type is the same as that for bla OXA-181 -positive K. pneumoniae reported from New Zealand (3). Both patients died of their illnesses.
OXA-181 is a close relative of OXA-48 from which it differs by 4 aa (4). bla OXA-181 -positive K. pneumonia infections were fi rst described in India but imported cases have since been described in Oman, the Netherlands, 1524 Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 18, No. 9, September 2012 and New Zealand (3-5,7). We were unable to confi rm the original source of these isolates, and continuous surveillance for carbapenemase producers in our hospital has not uncovered any bla OXA-181 -positive isolates since 1996. To our knowledge, there are no reports of bla OXA-181positive isolates in Bangladesh. However, this country borders India, which is a source of bla OXA-181 -positive Enterobacteriaceae. These cases highlight potential problems that may arise from medical tourism (the rapidly increasing practice of traveling across international borders to obtain health care) and document the expanding range of a newly emerging mechanism of carbapenem resistance.

Dengue Fever in South Korea, 2006-2010
To the Editor: Dengue fever is an acute, febrile disease caused by a fl avivirus and is transmitted by Aedes spp. mosquitoes (1). South Korea is not considered as a region to which dengue virus is endemic because it is located above 35°N latitude and has an isotherm of 10°C in winter, which potentially limits year-round survival of Aedes aegypti mosquitoes (1,2). Thus, dengue fever was seldom recognized as a public health concern in South Korea. However, the fi rst case of dengue fever in South Korea was reported in 1995 in a woman who had traveled to Sri Lanka (3). A second case was found in a sailor who had worked in countries in Africa in 2000 (4).
Since 2001, dengue fever has been a notifi able infectious disease in South Korea because of concerns about increasing international travel as a source of infection and because the less effi cient potential dengue vector, Ae. albopictus mosquitoes, were found in this country. All cases reported through the surveillance system should be complemented by thorough epidemiologic investigations to determine whether a case was imported or originated in South Korea. Thus, we analyzed dengue fever-associated data from the Korea Centers for Disease Control and Prevention.
During 2006-2010, a total of 367 suspected cases were reported by physicians through the National Infectious Disease Surveillance System. IgM ELISA and reverse transcription PCR results identifi ed 324 cases as dengue fever. Investigation of 34 cases could not be completed because some cases were in foreigners and in Korean persons who resided in foreign countries, left South Korea after diagnosis, or could not be reached by the contact information that was provided. Investigation of 290 cases was completed by reviewing medical records and by interviews. Interviews were conducted by provincial and Korea Centers for Disease Control and Prevention Epidemic Intelligence Service offi cers, who used a standardized investigation form.
All 290 case-patients had a history of international travel before onset of dengue fever symptoms.