Sepsis in neonates due to imipenem-resistant Klebsiella pneumoniae producing NDM-1 in India.

Sir, Treatment of neonatal infections is becoming increasingly difficult due to multidrug-resistant organisms. Carbapenems are the last resort for the treatment of severe infections, however, the emergence of carbapenemases in Enterobacteriaceae has left the clinician cornered with very few options. Recently a new carbapenemase designated New Delhi metallo-blactamase (NDM-1) was identified in Klebsiella pneumoniae. Most reported cases of infection with NDM-1 producers have involved adult patients. This communication reports the presence of blaNDM-1 in two isolates of K. pneumoniae from neonates admitted to a neonatal intensive care unit (NICU) at a tertiary care centre in India. The first neonate was clinically septic. Imipenem-resistant K. pneumoniae (Kp-1) was isolated from an endotracheal aspirate, but blood culture was negative. The patient was started on colistin, however, the parents removed the child from the hospital against medical advice and the patient was lost to follow-up. The other neonate was born at a different hospital and was admitted to the NICU with suspected sepsis. Blood culture yielded imipenem-resistant K. pneumoniae (Kp-2). A combination of colistin and minocycline was given for a period of 10 days, after which the patient recovered and was discharged. The identity of the isolates was confirmed by an ID 32 E kit (bioMérieux, Marcy l’Étoile, France). A disc diffusion test using antibiotics (BD Diagnostics, Franklin Lakes, NJ, USA) was performed according to CLSI guidelines. MICs were determined using Etest (AB Biodisk, Solna, Sweden). MICs were also determined with 40 mg/L phenylalanine arginine b-naphthylamide (PAbN) (Sigma-Aldrich, St Louis, MO, USA). Testing with the cephalosporin/clavulanic acid combination disc test, modified Hodge test and imipenem/EDTA double-disc combination tests was also undertaken. Both isolates were resistant to a range of antibiotics, including b-lactams, quinolones and aminoglycosides. Kp-1 was susceptible only to colistin and tigecycline, but Kp-2 was susceptible to colistin, tigecycline, tetracycline, minocycline and doxycycline (Table 1). Both isolates showed phenotypic evidence of carbapenemase, metallo-b-lactamase (MBL) and extended-spectrum b-lactamase (ESBL) production. Augmentation of the zone was noted in both isolates with ceftazidime, but not cefotaxime. Investigations of production of AmpC using cefoxitin, cefoxitin with 3-aminophenylboronic acid (APB) (Sigma) and cefoxitin plus APB containing EDTA (Sigma) were negative. PFGE performed following PulseNet standardized procedures with XbaI (http://www.cdc.gov/pulsenet/protocols.htm) demonstrated that the two isolates were clonally distinct (Figure S1, available as Supplementary data at JAC Online). The MICs of imipenem were .32 mg/L and not affected by the presence of PAbN, indicating that efflux did not contribute to carbapenem resistance. To elucidate the mechanism of carbapenem resistance, PCR for blaKPC, 5 blaVIM,IMP,SPM-1,GIM-1,SIM-1 2 and blaOXA-23,OXA-24,OXA-48,OXA-58 6 was carried out as previously described. Detection of NDM-1 was performed by PCR with Research letters