Biofilm formation and antimicrobial susceptibility of Staphylococcus epidermidis strains from a hospital environment

Abstract

The hospital environment microflora comprise a wide variety of microorganisms which are more or less pathogenic and where staphylococci are one of the most common types. The aim of the presented study was to evaluate the prevalence of the biofilm forming coagulase-negative staphylococci (CoNS) in a hospital environment as a risk factor for nosocomial infections. Among 122 isolated and tested strains of CoNS the most frequent were: S. epidermidis-32 strains, S. haemolyticus-31 strains, S. capitis subsp. capitis- 21 strains, S. hominis-11 strains, S. cohnii subsp. cohnii-nine strains. In case of CoNS, the main molecule responsible for intercellular adhesion is a polysaccharide intercellular adhesin (PIA), encoded on the ica gene operon. The analysis revealed the presence of the icaADBC operon genes in 46.88% of S. epidermidis isolates. IcaA and icaD were present in 34.38% and 28.13% of strains respectively while IcaC gene was present in 37.50% of strains. IcaB gene was found in 21.88% of S. epidermidis strains. In 15 (63%) strains all icaADBC operon genes were observed. The assessment of antibacterial drugs susceptibility demonstrated that analyzed CoNS strains were highly resistant to macrolides and lincosamides and more sensitive to rifampicin and linezolid. Our data indicates that the hospital environment can be colonized by biofilm forming coagulase-negative staphylococci and transmission of these strains can cause an increased risk of serious nosocomial infections.

Figure 1

The proportion of susceptible and resistant CoNS strains to the tested chemotherapeutics.

Figure 2

The proportion of susceptible and resistant S. epidermidis strains to the tested chemotherapeutics.

Figure 3

Detection of operon icaADBC genes in Staphylococcus epidermidis strains. (A) PCR results with primer for icaA, positive probe—the presence of the 814-bp product; (B) PCR results with primer for icaB and icaD, positive probe—the presence of the 526-bp product to icaB and 371-bp product to icaD; and (C) PCR results with primer for icaC genes, positive probe—the presence of the 989-bp product. Line 1—molecular size maker 100-1000-bp, line 2-9 different S. epidermidis strains.