Association between biofilm formation, structure and antibiotic resistance in Staphylococcus epidermidis isolated from neonatal septicemia in southwest Iran

Infection and Drug Resistance Dovepress open access to scientific and medical research Infection and Drug Resistance downloaded from https://www.dovepress.com/ by 88.198.20.149 on 03-Aug-2019 For personal use only. Open Access Full Text Article ORIGINAL RESEARCH Association between biofilm formation, structure and antibiotic resistance in Staphylococcus epidermidis isolated from neonatal septicemia in southwest Iran This article was published in the following Dove Press journal: Infection and Drug Resistance Ahmad Farajzadeh Sheikh1,2 Aram Asareh Zadegan Dezfuli2 Tahereh Navidifar2 Shahla Samei Fard2 Masood Dehdashtian3 1 Infectious and Tropical Diseases Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran; 2 Department of Microbiology, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran; 3 Neonatology Ward Imam Khomeini Teaching Hospital, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Background: Staphylococcus epidermidis has emerged as the pathogen from neonatal septicemia. Antibiotic resistance and the capability of biofilm formation make these infections much harder to treat. Hence, the aim of this study was to investigate the association between biofilm formation, structure and antibiotic resistance in S. epidermidis isolated from neonatal septicemia. Methods: Overall, 65 S. epidermidis isolates were recovered from blood cultures of neonatal septicemia. Antibiotic resistance pattern and the biofilm production were determined using phenotypic methods. The presence of ica operon, the bhp, the aap genes and SCCmec types were screened using PCR. Results: Most S.epidermidis isolates were resistant to erythromycin, while all isolates were sensitive to linezolid and vancomycin. Fifty-three percent of S.epidermidis isolates were resistant to methicillin. SCCmec types II was found commonly among methicillin-resistant S. epidermidis (MRSE) strains. The biofilm formation was observed in 65% of S.epidermidis isolates and the majority have polysaccharide matrix. icaA and icaD genes were found in 40% and 19% of isolates. Twenty-three isolates (62%) produced dissolvable polysaccharide intercellular adhesion (PIA)-dependent biofilms in SM after growth in TSB with NaCl and 14 (37%) isolates produced dissolvable protein-dependent biofilms in PK after growth in TSB with glucose. Three isolates (62%) produced dissolvable polysaccharide intercellular adhesion. Conclusion: Our data indicate the high rates of antibiotic resistance and the capability of biofilm formation among S. epidermidis isolates. Hence, the transmission of these strains can cause an increased risk of serious nosocomial infections. Keywords: S. epidermidis, antibiotic resistance, biofilm formation Introduction Correspondence: Aram Asareh Zadegan Dezfuli Department of Microbiology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Tel +98 916 303 2873 Email 1771 submit your manuscript | www.dovepress.com Infection and Drug Resistance 2019:12 1771–1782 DovePress © 2019 Farajzadeh Sheikh et al. This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at https://www.dovepress. com/terms.php and incorporate the Creative Commons Attribution – Non Commercial (unported, v3.0) License (http://creativecommons.org/licenses/by-nc/3.0/). By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. For permission for commercial use of this work, please see paragraphs 4.2 and 5 of our Terms (https://www.dovepress.com/terms.php). http://doi.org/10.2147/IDR.S204432 Powered by TCPDF (www.tcpdf.org) Septicemia is one of the leading causes of neonatal mortality and morbidity worldwide. According to the World Health Organization report (WHO), more than 3 million newborns suffer from septicemia globally.1 According to a previous study in Iran, the rate of neonatal septicemia has been reported between 12% and 16.7%.2 In the last two decades, coagulase-negative staphylococci (CoNS) group especially Staphylococcus epidermidis, a normal flora of the skin, has emerged as a common cause of septicemia in the neonatal intensive care units (NICUs) especially in late-onset sepsis (LOS).3 Neonatal sepsis can be considered either as Dovepress Infection and Drug Resistance downloaded from https://www.dovepress.com/ by 88.198.20.149 on 03-Aug-2019 For personal use only. Farajzadeh Sheikh et al early onset sepsis (EOS) occurring in the first 72 hours of age or LOS which follows after 72 hours of age.4 LOS has been well recognized to be associated with prematurity, invasive interventions like intravascular catheterization, failure in early enteral feeding, prolonged antibiotic treatment, andhospitalization.5 The presence of S. epidermidis on human skin may allow S. epidermidis to form biofilm over medical implants and easily invade the bloodstream through indwelling catheters.6 The microorganisms attach to surfaces and produce extracellular polysaccharides, resulting in the formation of a biofilm.7 Biofilms are a serious problem for public health because of the increased resistance of biofilm-associated organisms to antimicrobial agents by slow diffusion of conventional antibiotics through the extracellular polymeric substance and the potential for these organisms to cause infections in patients with indwelling medical devices.7,8 The biofilm formation and the antibiotic resistance of the S. epidermidis isolates can be one of the important reasons for prolonging the period of treatment of infants.9 In S. epidermidis, the expression of several genes is associated with the biofilm formation, including icaABCD locus that encodes the polysaccharide intercellular adhesion (PIA), the bhp gene that encodes a cell wall surface anchor protein and the aap gene that encodes an accumulation-associated protein.10 Otto et al indicated that in strains that lack the ica locus, biofilm formation is due to the presence of aap gene, which enables bacteria to bind to various matrix proteins.11 Recently, increasing resistance of S. epidermidis strains to glycopeptide agents and methicillin has spurred high interests in understanding molecular mechanisms of antibiotic resistance.6,11 Similar to Staphylococcus aureus, the mechanism of methicillin resistance is mediated by the mecA gene which encodes penicillin binding protein 2a (PBP 2a) with reduced affinity for beta-lactam antibiotics.12 It is believed that CoNS acts as an important reservoir of resistance-associated mobile genetic elements, which can be transferred between staphylococcal species. The mecA gene is located on a mobile genetic element called the staphylococcal cassette chromosome mec (SCCmec). Moreover, SCCmec compromises two main components: the ccr gene complexccrand the mec gene c (...truncated)