A Case of New Delhi Metallo-β-Lactamase 1 (NDM-1)-Producing Klebsiella pneumoniae with Putative Secondary Transmission from the Balkan Region in the Netherlands

LETTER

New Delhi metallo-beta-lactamase 1 (NDM-1) was first identified in 2008 in a Klebsiella pneumoniae strain from a Swedish patient of Indian origin with a history of medical treatment in a New Delhi hospital for a urinary tract infection (12). Since then, more such cases in different parts of the world have been reported (6). The majority of these patients were found to have traveled to or been admitted to hospitals in the Indian subcontinent. A few patients had a travel history in the Balkan area (11). Here we describe a Dutch patient proven to be carrying an NDM-1-producing K. pneumoniae strain that was imported from the Balkan area. Furthermore, a second patient apparently acquired this strain during her stay in the same hospital as the index case.

Patient A, a 66-year-old female with a cerebrovascular accident, was transferred from a hospital in Belgrade, Serbia, to the neurology department of a hospital in the east of the Netherlands on 27 August 2008. Since the patient was known to carry methicillin-resistant Staphylococcus aureus (MRSA), she was directly placed in a separate room in isolation. During admission, extended-spectrum β-lactamase (ESBL)-producing K. pneumoniae, as determined according to the 2008 CLSI guidelines (2), was isolated from different sites, including throat, rectum, and urinary tract. The patient was treated for the urinary tract infection with nitrofurantoin, to which the isolate was susceptible, and with removal of the urinary catheter. She was discharged from the hospital on 15 October to a nursing home, where contact isolation measures were maintained. Follow-up screening cultures remained positive for ESBL-producing K. pneumoniae up to March 2009, but subsequent cultures obtained on several occasions between April and September 2009 were negative.

Patient B, a 73-year-old female with no travel history outside the Netherlands, was admitted with exacerbation of pulmonary symptoms to the department of pulmonary disease (DPD) in the same hospital as the first patient between 10 October and 7 November 2008. At the end of October, ESBL-producing K. pneumoniae was cultured from a urine specimen. The patient was treated with oral amoxicillin-clavulanate in addition to removal of the urinary catheter and was discharged from the hospital in good condition. A urinary culture obtained during readmission to the DPD on 25 June 2010 with pulmonary symptoms and urinary tract infection yielded only Escherichia coli. For the urinary tract infection, the patient was treated with ciprofloxacin, to which the E. coli strain was susceptible. The patient died on 18 July 2010.

Two ESBL-producing K. pneumoniae isolates, one from each of these two patients, were selected for further analysis aimed at the presence of carbapenemase because of their elevated MICs to meropenem according to the 2008 CLSI guidelines (2). Antimicrobial susceptibility testing using the EUCAST breakpoints (www.eucast.org) was performed with the Vitek2 automated system (bioMérieux). Ertapenem, imipenem, meropenem, tigecycline, and colistin MIC values were determined by the Etest. The results of retrospective antimicrobial susceptibility testing and phenotypic confirmations are shown in Table 1. PCR and sequencing (9) confirmed the presence of NDM-1, CTX-M-15, SHV-12, and OXA-1. Molecular plasmid analysis (9) revealed the presence of a 70-kb IncII plasmid containing bla_NDM-1 and a 140-kb plasmid. By amplified fragment length polymorphism (AFLP) typing (10), the strains were shown to be identical (data not shown), a result which strongly suggests that the strain was transmitted from the index patient to the secondary case, although the transmission pathway remains unknown.

Table 1.

Results of antimicrobial susceptibility testing and phenotypic confirmations for two ESBL-producing K. pneumoniae isolates, one from each of the two cases

Patient	Specimen	MIC (μg/ml)										Phenotypic confirmationc
		Ceftazidime	Cefepime	Gentamicin	Tobramycin	Ciprofloxacin	Imipenem	Meropenem	Ertapenem	Colistin	Tigecycline	ESBLd	MHT fore:		CDf imipenem-EDTA	Ertapenem-boronic acidg
													Imipenem	Meropenem
1a	Urine	>64	32	>16	>16	>4	8	3	6	0.25	1.5	Pos	Pos	Pos	Pos	Neg
2b	Urine	>64	32	>16	>16	>4	6	3	6	0.19	1.5	Pos	Pos	Pos	Pos	Neg

^aIndex patient.

^bSecondary case.

^cPos, positive; neg, negative.

^dESBL, extended-spectrum beta-lactamase (laboratory detection of highly resistant microorganisms [HRMO]; http://www.nvmm.nl).

^eMHT, modified Hodge test (3).

^fCD, combined disc (7).

^gSee reference 5.

By multilocus sequence typing (MLST) (4), the strain of the index patient was found to belong to sequence type 15 (ST15). This MLST type was recently described in Belgium for an NDM-1-producing K. pneumoniae isolate from a patient who had been previously hospitalized in Podgorica, Montenegro (1). The strain from the secondary case was ST431, an MLST type with only one base pair change from ST15. In conclusion, our study describes one of the first cases of NDM-1-producing K. pneumoniae with apparent secondary transmission, as evidenced by the findings from AFLP typing. Furthermore, the strain belongs to ST15, which has recently been isolated from a patient returning from the Balkan area, supporting the hypothesis of the Balkan region as a reservoir of NDM-1-producing Gram-negative bacteria (8).