Correlation Between Biofilm-Formation and the Antibiotic Resistant Phenotype in Staphylococcus aureus Isolates: A Laboratory-Based Study in Hungary and a Review of the Literature

Seyyed Askhan Senobar Tahaei; Anette Stájer; Ibrahim Barrak; Eszter Ostorházi; Dóra Szabó; Márió Gajdács

doi:10.2147/IDR.S303992

Correlation Between Biofilm-Formation and the Antibiotic Resistant Phenotype in Staphylococcus aureus Isolates: A Laboratory-Based Study in Hungary and a Review of the Literature

Infect Drug Resist. 2021 Mar 23:14:1155-1168. doi: 10.2147/IDR.S303992. eCollection 2021.

Authors

Seyyed Askhan Senobar Tahaei¹, Anette Stájer², Ibrahim Barrak², Eszter Ostorházi³, Dóra Szabó³, Márió Gajdács^{1

3}

Affiliations

¹ Department of Pharmacodynamics and Biopharmacy, Faculty of Pharmacy, University of Szeged, Szeged, 6720, Hungary.
² Department of Periodontology, Faculty of Dentistry, University of Szeged, Szeged, 6720, Hungary.
³ Institute of Medical Microbiology, Faculty of Medicine, Semmelweis University, Budapest, 1089, Hungary.

Abstract

Introduction: Staphylococcus aureus (S. aureus) is an important causative pathogen in human infections. The production of biofilms by bacteria is an important factor, leading to treatment failures. There has been significant interest in assessing the possible relationship between the multidrug-resistant (MDR) status and the biofilm-producer phenotype in bacteria. The aim of our present study was to assess the biofilm-production rates in clinical methicillin-susceptible S. aureus [MSSA] and methicillin-resistant S. aureus [MRSA] isolates from Hungarian hospitals and the correlation between resistance characteristics and their biofilm-forming capacity.

Methods: A total of three hundred (n=300) S. aureus isolates (corresponding to MSSA and MRSA isolates in equal measure) were included in this study. Identification of the isolates was carried out using the VITEK 2 ID/AST system and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Antimicrobial susceptibility testing was performed using the Kirby-Bauer disk diffusion method and E-tests, confirmation of MRSA status was carried out using PBP2a agglutination assay. Biofilm-production was assessed using the crystal violet (CV) tube-adherence method and the Congo red agar (CRA) plate method.

Results: There were significant differences among MSSA and MRSA isolates regarding susceptibility-levels to commonly used antibiotics (in case of erythromycin, clindamycin and ciprofloxacin: p<0.001, gentamicin: p=0.023, sulfamethoxazole/trimethoprim: p=0.027, rifampin: p=0.037). In the CV tube adherence-assay, 37% (n=56) of MSSA and 39% (n=58) of MRSA isolates were positive for biofilm-production, while during the use of CRA plates, 41% (n=61) of MSSA and 44% (n=66) of MRSA were positive; no associations were found between methicillin-resistance and biofilm-production. On the other hand, erythromycin, clindamycin and rifampin resistance was associated with biofilm-positivity (p=0.004, p<0.001 and p<0.001, respectively). Biofilm-positive isolates were most common from catheter-associated infections.

Discussion: Our study emphasizes the need for additional experiments to assess the role biofilms have in the pathogenesis of implant-associated and chronic S. aureus infections.

Keywords: Congo red agar; MRSA; MSSA; Staphylococcus aureus; antibiotic resistance; biofilm; crystal violet; phenotypic assay.

Grants and funding

The article processing charge (APC) was funded by the University of Szeged Open Access fund (ID: 5175). M.G. was supported by the János Bolyai Research Scholarship (BO/00144/20/5) of the Hungarian Academy of Sciences and the New National Excellence Programme (ÚNKP-20-5-SZTE-330) of the Ministry of Human Resources. Support from Ministry of Human Capacities, Hungary grant 20391-3/2018/FEKUSTRAT is acknowledged. M.G. would also like to acknowledge the support of ESCMID’s “30 under 30” Award.