Molecular, Phenotypic Characterization, Antimicrobial Susceptibility Profile of Staphylococcal Strains Isolated from Preterm Neonates at Neonatal Intensive Care Unit with Clinical Characteristics and Risk Factor of these Cases

Aim of the Work: The aim of work is to study the prevalence of different staphylococcal species in preterm neonates with septicemia at neonatal intensive care unit over a period of one year and their antimicrobial susceptibility profile.

Materials and Methods: This prospective study was conducted on 80 neonates admitted to neonatal intensive care unit in Tanta University hospitals. Blood culture was done and staphylococci were isolated and identified by conventional culture methods which were confirmed by biochemical reactions. Antibiotic susceptibility profile of the isolated strains was done by disc diffusion method. Molecular characterization of MRSA (methicillin resistant Staph. aureus) strains was done by Polymerase chain reaction.

Results: Out of 80 cases of preterm infants with septicemia staphylococci were isolated from 12 cases (15%), 20 (25%) cases showed no growth of microorganisms, organisms other than staphylococci were isolated from 48 cases (60%). Of 12strains of staphylococci; 5 strains (5.25%) were identified as coagulase negative staphylococci (CoNS), 8 isolates (8.75%) were identified as Staphylococcus aureus which were divided as 3 strains MRSA (3.75%), and 4 stains (5%) MSSA (Methicillin sensitive Staph. aureus). As regard antimicrobial susceptibility profile; 60 % of MRSA strains were sensitive to meropenem, gentamicin, and ciprofloxacin, 33.3% only were sensitive to cefotaxime, vancomycin and cefepime. whereas MSSA recorded highest sensitivity to oxacillin and vancomycin (100%) while the least sensitivity was to cefepime (25%). CoNS (coagulase negative staphylococci) strains showed highest sensitivity to gentamycin (80%) and the lowest sensitivity was to vancomycin and cefepime.

Conclusion: Neonatal sepsis caused by staphylococci represents a major cause of morbidity and mortality in NICU (Neonatal Intensive care unit). Each staphylococcus species had a definite Antimicrobial susceptibility profile which must be taken in consideration before decision of the plan of antimicrobial therapy.