Study of coagulase-negative staphylococci in hospital-acquired neonatal sepsis

Abstract

Background Coagulase-negative staphylococci (CoNS) has become increasingly prevalent as the leading cause of late-onset bacteremia in neonatal ICUs. Diagnosing CoNS septicemia poses challenges because this bacterium commonly resides on the skin, leading to potential contamination of blood culture samples. Therefore, this study aimed to identify the bacterial causes of sepsis in neonates who exhibit clinical signs of the condition, also to assess the methicillin susceptibility of CoNS through both phenotypic and molecular methodologies. Materials and methods This study was carried out at Mansoura University Children Hospital. Blood samples were obtained and directly cultured using the BACT/ALERT system. All isolates were identified using BD Phoenix system. CoNS isolates were subjected to a disk diffusion susceptibility test with cefoxitin 30 µg, serving as an initial screening test to identify methicillin resistance. Automated antibiotic susceptibility was done using BD Phoenix system followed by PCR testing to detect the presence of the mecA gene in resistant CoNS isolates. Results Among all the isolated micro-organisms, Klebsiella pneumoniae and CoNS were found to be significantly higher in early-onset sepsis and late-onset sepsis, respectively. Staphylococcus epidermidis constituted 30% of the isolates, with Staphylococcus haemolyticus and Staphylococcus hominis each accounting for 20%, while other Staphylococcus species made up the remaining 20%. Among the identified CoNS, 47.4% tested positive for the mecA gene. The presence of the mecA gene was significantly associated with a higher incidence of late-onset sepsis (P=0.033). Conclusion CoNS are the predominant culprits behind late-onset sepsis in hospitalized newborns. Notably, the presence of the mecA gene was significantly linked to a higher occurrence of late-onset sepsis. Our study has uncovered a concerning surge in antibiotic resistance genes within our community. This underscores the urgency of implementing an active antibiotic surveillance program and exploring alternative therapeutic strategies to effectively combat neonatal sepsis.