Indian Journal of Medical Microbiology Medknow Publications on behalf of Indian Association of Medical Microbiology ISSN: 0255-0857 EISSN: 1998-3646 Vol. 28, Num. 4, 2010, pp. 416-417

Indian Journal of Medical Microbiology, Vol. 28, No. 4, October-December, 2010, pp. 416-417

Correspondence

Carbapenem resistance in Acinetobacter baumannii isolated from blood of neonates with sepsis

S Roy¹, S Basu¹, S Dasgupta², AK Singh², R Viswanathan²

¹ Department of Bacteriology, National Institute of Cholera and Enteric Diseases, Kolkata, India
² Department of Neonatology, Institute of Post Graduate Medical Education & Research, Kolkata, India
Correspondence Address: R Viswanathan, Department of Neonatology, Institute of Post Graduate Medical Education & Research, Kolkata, India
rupa_vish@rediffmail.com

Date of Submission: 22-Jul-2010
Date of Acceptance: 28-Aug-2010

Code Number: mb10127

PMID: 20966591
DOI: 10.4103/0255-0857.71814

Dear Editor,

Acinetobacter baumannii is one of the emerging causes of neonatal sepsis in India. ^[1] Carbapenem resistance mediated by carbapenemases, such as metallo betalactamases (MBL) or oxacillinases (OXA enzymes), are of maximum concern due to the chance of rapid dissemination.^[2] Infection with such resistant organisms also limits therapeutic options. The present study of carbapenem resistance in neonatal blood culture isolates of A. baumannii was carried out in a 20-bedded, level III neonatal unit in a tertiary care teaching hospital in Kolkata.

Twelve isolates of A. baumannii from blood culture of septic neonates isolated during 2007 and 2008 were studied. Four isolates were carbapenem resistant as confirmed by disc diffusion ^[3] and E Test (AB biodisk, Solna, Sweden). These isolates were multidrug resistant as well. Carbapenem resistance was mediated by oxacillinases in all isolates as determined by polymerase chain reaction (PCR) for oxacillinases (bla_oxa-51 -like, bla_oxa-58 -like, bla_oxa-23 -like and bla_oxa-24 -like). None of the isolates were MBL producers, as confirmed by multiplex PCR for bla _IMP gene, bla _VIM gene and bla _SIM gene. ^[4] Nucleotide sequence determination was done to analyse the resistance genotypes of the isolates by direct sequencing of the PCR-amplified fragments. PCR products were purified using QIAquick Gel Extraction Kit (Qiagen, Valencia, CA, USA) and were sequenced directly on both strands using the BigDye Terminator v ^3.1 Cycle Sequencing Kit and analysed with an automated sequencer ABI3100 genetic analyzer (Applied Biosystems , Foster City, CA, USA). Similarity searches for the nucleotide sequences were performed with BLAST program ( http://www.ncbi.nlm.nih .) [Table - 1]. All the isolates were diverse strains as confirmed by pulsed-field gel electrophoresis (PFGE)^[5] [Figure - 1]. The four babies infected with carbapenem resistant A. baumannii expired [Table - 1].

A. baumannii can persist in the hospital environment and has the ability to develop resistance to a majority of antimicrobials. ^[6] Carbapenem resistance is especially dangerous as almost no options are left for treatment, particularly in neonates, in whom potential alternatives like polymyxins are not routinely used. The study highlights the emergence of carbapenem resistance in A. baumannii in neonatal blood stream infections in a tertiary care hospital. Selection of carbapenem resistant isolates of Acinetobacter in the NICU could have been aided by the practice of higher use of antimicrobials including cephalosporins and aminoglycosides, as seen in other studies. ^[7] In conclusion, we report the presence of carbapenem resistant A. baumannii as a pathogen in a neonatal unit in eastern India. OXA-23-like gene was found to be the most prevalent gene responsible for carbapenem resistance. No MBLs were detected. Though the sample size is small, the study indicates the emergence of carbapenem resistant A. baumannii in neonatal infections. Urgent steps need to be taken to prevent the spread of such resistant organisms in the neonatal intensive care units.

References

1.	Arora U, Jaitwani J. Acinetobacter spp. - An emerging pathogen in neonatal septicaemia in Amritsar. Indian J Med Microbiol 2006;24:81.  Back to cited text no. 1  [PUBMED]
2.	Poirel L, Nordmann P. Carbapenem resistance in Acinetobacter baumannii: Mechanisms and epidemiology. Clin Microbiol Infect 2006;9:826-36.  Back to cited text no. 2
3.	Clinical and Laboratory Standards Institute. Performance Standards for Antimicrobial Susceptibility Testing. Eighteenth Information Supplement. CLSI document M100-S18, 2008; Pennsylvania, USA.  Back to cited text no. 3
4.	Mostachio AK, van der Heidjen IM, Rossi F, Levin AS, Costa SF. Multiplex PCR for rapid detection of genes encoding Oxa and metallo-beta-lactamases in carbapenem resistant Acinetobacter spp. J Med Microbiol 2009;58:1522-4.   Back to cited text no. 4
5.	Corbella X, Montero A, Pujol M, Domνnguez MA, Ayats J, Argerich MJ, et al. Emergence and rapid spread of carbapenem resistance during a large and sustained hospital outbreak of multiresistant Acinetobacter baumannii. J Clin Microbiol 2000;38:4086-95.  Back to cited text no. 5
6.	Cisneros JM, Rodriguez -Bano R. Nosocomial bacteraemia due to Acinetobacter baumannii: Epidemiology, clinical features and treatment. Clin Microbiol Infect 2002;8:687-93.  Back to cited text no. 6
7.	Asensio A, Oliver A, Gonzαlez-Diego P, Baquero F, Pιrez-Dνaz JC, Ros P, et al. Outbreak of a multiresistant Klebsiella pneumoniae strain in an intensive care unit: Antibiotic use as risk factor for colonization and infection. Clin Infect Dis 2000;30:55-60.  Back to cited text no. 7

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