The Study of Persistence of S. epidermidis and S. haemolyticus in a Children’s Hospital

Introduction : Staphylococcal infections rank high among healthcare­associated infections. Coagulase­negative staphylococci, especially S. epidermidis and S. haemolyticus , often induce inflammatory processes in newborns. In this regard, it is important to study the persistence of these microorganisms in pediatric hospitals using intraspecific differentiation based on the comparison of spectra of their extracellular proteins. Our objective was to study circulation of S. epidermidis and S. haemolyticus strains in a children’s hospital by electrophoretyping of their extracellular proteins. Materials and methods : We studied 277 strains of S. haemolyticus and 267 strains of S. epidermidis isolated from patients and various objects of the hospital environment by obtaining extracellular proteins of the isolates, analyzing them using polyacrylamide gel electrophoresis, and determining their antibiotic resistance and ability to form biofilms. Results : The analysis of electrophoregrams of extra­ cellular proteins of staphylococci revealed groups of identical strains. Isolates from different patients were combined into 21 S. haemolyticus groups comprising of 69 strains and 13 groups of S. epidermidis comprising of 38 strains. All the cultures were methicillin­resistant, with the exception of one group of two S. haemolyticus strains. More than half of the cultures grouped by spectra of extracellular proteins were multidrug resistant. The absolute majority of S. haemolyticus strains (97.2 %) and three quarters of S. epidermidis strains (76.0 %) were able to form biofilms. The average values of the degree of film formation in S. haemolyticus strains were significantly higher than those in S. epidermidis . Conclusions : Of all the studied cultures of staph­ ylococci, 25 % of strains and 14 % of S. epidermidis strains persisted and were endemic in the children’s hospital, including 88.4 % of hemolytic and 42.1 % of epidermal staphylococcus strains for more than a month, and 21.7 % of S. haemolyticu s and 21.1 % of S. epidermidis strains for almost a year. The strains were resistant to methicillin, and the isolates of S. haemolyticus had a high ability to form biofilms.