Evaluation of Biofilm Formation and Prevalence of Multidrug-Resistant Strains of Staphylococcus epidermidis Isolated from Neonates with Sepsis in Southern Poland

Abstract

<i>Staphylococcus epidermidis</i> strains play an important role in nosocomial infections, especially in the ones associated with biofilm formation on medical devices. The paper was aimed at analyzing the mechanisms of antibiotic resistance and confirming the biofilm-forming ability among <i>S. epidermidis</i> strains isolated from the blood of hospitalized newborns. Genetic analysis of resistance mechanism determinants included multiplex PCR detection of <i>mecA</i>, <i>ermA</i>, <i>ermB, ermC</i>, <i>msrA</i>, and <i>mef</i> genes. Biofilm analysis comprised phenotypic and genotypic methods including Christensen and Freeman methods and PCR detection of the <i>ica</i>ADB gene complex. Among the tested <i>S. epidermidis</i> strains, 89% of the isolates were resistant to methicillin, 67%-to erythromycin, 53%-to clindamycin, 63%-to gentamicin, and 23%-to teicoplanin, while all the strains were susceptible to vancomycin and linezolid. The <i>mecA</i> gene was detected in 89% of the isolates, the <i>ermC</i> gene was the most common and present among 56% of the strains, while the <i>msrA</i> gene was observed in 11% isolates. Eighty-five percent of the strains were described as biofilm-positive by phenotypic methods and carried the <i>icaADB</i> gene cluster. Multidrug resistance and the biofilm-forming ability in most of the strains tested may contribute to antimicrobial therapy failure (<i>p</i> < 0.05).