Isolation of MRSA, ESBL and AmpC - β -lactamases from Neonatal Sepsis at a Tertiary Care Hospital

Background and Objectives: The emergence of methicillin resistant Staphylococcus aureus (MRSA) and extended spectrum β–lactamases (ESBLs) in neonatal intensive care unit patients is increasing. This study aims to find out the bacteriological profile in neonatal sepsis and study their antimicrobial susceptibility pattern including detection of MRSA and ESBLs. Materials and Methods: This study was conducted for a period of one and a half years from January 2010 to June 2011 in a tertiary care hospital in Chennai. A total of 182 blood samples were collected using sterile precautions. They were processed following standard laboratory protocol. Antibiogram was done using appropriate antibiotics by Kirby-Bauer disc diffusion method. Isolated Staphylococcus aureus were tested for methicillin resistance using Cefoxitin disc (30μg), ESBL was detected using combined disc method, MIC reduction and Polymerase chain reaction, metallobetalactamases using EDTA and Amp-C beta lactamases using AmpC disc test. C-reactive protein (CRP) was estimated for all the cases. Results: Out of the 182 cases, 110 (60.4%) were culture positive. Fifty five (63.9 %) of early onset sepsis cases had Gram negative bacteria (GNB) and 19 (79.1%) of late onset sepsis cases had Gram positive bacteria. Out of the total pathogens, 31 (28.1%) were Klebsiella pneumoniae and 30 (27%) were Staphylococcus aureus. 17 (56.6 %) of Staphylococcus aureus were found to be MRSA and they were 100% sensitive to Vancomycin. 33 (67.3%) of Enterobacteriaceae were ESBL producers. ESBL isolates were 100% sensitive to Imipenem. Three (6.1%) of Enterobacteriaceae were AmpC producers and 3 (27.2%) of Pseudomonas aeruginosa were MBL producers. CRP was positive in 99 (54.3%) cases, out of which 94 (94.9%) were culture positive. Conclusion: Klebsiella spp. and Staphylococcus aureus were the commonest bacteria causing neonatal sepsis in this centre. Multidrug resistance among the isolates was common. Early diagnosis and institution of specific antibiotics after studying the sensitivity pattern will help in reducing neonatal morbidity and mortality and prevent emergence of drug resistant strains.