A Comparative Evaluation of Microbial Pattern and Antibiotic Susceptibility in a Level III NICU Between Two Decades


Background: Sepsis is one of the most common causes of neonatal mortality and morbidity in NICUs. Prescription of broad-spectrum antibiotics is increasing; hence, increase in antibiotic resistance is a concern. Information about changing microbial patterns and antimicrobial sensitivity over time helps us to choose the most appropriate antibiotics.

Objectives: The aim of this research was to assess the changing microbial patterns and antibiotic susceptibility during a 23-year interval from 1992 to 2015 in the NICU of the Mofid Children’s hospital in Tehran, Iran.

Methods: We conducted a retrospective comparative descriptive study between 1992 and 2015. Neonates with positive blood cultures were enrolled, and the microbial characteristics and antibiograms of the blood cultures were compared.

Results: One-hundred cases of positive blood cultures in 1992 and 103 cases in 2015 were analyzed and compared. Overall, 57% of neonates were male and 43% were female; 56% of the sepsis was late onset and 44% was early onset; 63% of neonates had term gestation and 37% were preterm. We found that the most common causes of positive blood culture isolated in 1992 were Staphylococcus aureus (59%) and Staphylococcus epidermidis (40.9%). In 2015, the most common causes were (coagulase negative staphylococci) CONS (33.98%) and Pseudomonas aeruginosa (20.3%). In the evaluation of antibiograms, the rate of resistance to cephalosporins, aminoglycosides (except tobramycin), and oxacillins increased from 1992 to 2015. In 2015, the sensitivity rate to imipenem, meropenem, ciprofloxacillin, vancomycin, and linezolid was greater than the resistance, whereas to piperacillin, colistin, and cefepim, and cefotaxim, the rate of resistance was higher. In the evaluation of antibiotic sensitivity based on microorganisms in 2015, piperacillin had the highest effectiveness against pseudomonas and Klebsiella, with no effectiveness against Acinetobacter. Ciprofloxacin had the highest effectiveness against E. coli and Klebsiella. One-hundred percent of Streptococci, 83.3% of Staphylococcus aureus, and 71.4% of coagulase negative Staphylococci were sensitive to vancomycin.

Conclusions: In this research, we found that the pattern of microbial and antibiotic sensitivity has changed, and overall antibiotic resistance is increasing. This is an indication that healthcare providers should use broad-spectrum antibiotics with caution.