Staphylococcus Aureus- The Predominant Pathogen in the Neonatal ICU of a Tertiary Care Hospital in Amritsar, India

Abstract

An early treatment and the appropriate and the rational use of antibiotics would minimize the risk of severe morbidity and mortality in neonatal sepsis, and reduce the emergence of multi-drug resistant organisms in intensive care units. For the success of an early empiric treatment, a periodic review of the cases to assess any changing trends in the infecting organisms and their antimicrobial susceptibility is important. To study the most commonly encountered bacterial pathogens which caused neonatal sepsis and their sensitivity patterns, so that guidelines could be prepared for a rational antibiotic therapy. This was a retrospective study which was conducted in the Department of Microbiology and the Neonatal Intensive Care Unit (NICU) at SGRDIMSAR, Amritsar, during June 2011 to June 2012. Blood specimens for culture were drawn from 311 newborns who were admitted in an NICU with sepsis. The specimens were inoculated into brain heart infusion broth. Subcultures were performed on days 1, 2, 3, 5, 7 and 10. The isolates were identified by doing standard biochemical tests. The antibiotic resistance patterns of the isolates were studied by the Kirby Bauer disc diffusion technique. A total of 131 organisms were isolated from the 311 blood cultures. These included Staphylococcus aureus (n=68), Coagulase Negative Staphylococcus (CoNS) (n=30), Klebsiella pneumoniae (n=10), Acinetobacter baumannii (n=9), Escherichia coli (n=05), Enterobacter cloacae (n=04), Citrobacter diversus (n=02), Pseudomonas aeruginosa (n=02) and Candida (n=01). Staphylococcus aureus was the main pathogen in both early and late-onset sepsis. On antibiotic sensitivity testing, 57.35% of the Staphylococcus aureus isolates were found to be methicillin resistant. More than 90% gram negative rods were resistant to amikacin. The resistance to the third generation cephalosporins varied between 50-55%. The resistance to ciprofloxacin was quite high; however, most of the isolates were susceptible to levofloxacin. A majority of the isolates were susceptible to piperacillin- tazobactum and imipenem. The present study emphasized the importance of periodic surveys on the microbial flora which was encountered in particular neonatal settings to recognize the trend.