In Vitro Evaluation of Antibiotic Efficacy Against Biofilms Formed by Staphylococci Isolated from Catheter Samples

Year 2025, Volume: 39 Issue: 3, 94 - 104, 31.12.2025

Yağmur Ekenoğlu Merdan , Filiz Kibar , Akgün Yaman

https://doi.org/10.54962/ankemderg.1740650

Abstract

Staphylococci are among the most common causes of catheter-related infections, with their ability to form biofilms posing a significant challenge to effective treatment. In this study, the antibiotic resistance profiles and biofilm formation capacities of Staphylococcus strains isolated from blood catheter samples were evaluated in vitro. Antibiotic susceptibility of a total of 65 isolates was determined using the VITEK-2 automated system and broth microdilution method. The mass of biofilm formed by the isolates was evaluated using the crystal violet staining method and classified according to the optical density (OD) values obtained. It was found that 54.8% of the isolates were biofilm-positive (BP). BP strains were more resistant to most antibiotics compared to biofilm-negative (BN) strains, this difference was statistically significant for ciprofloxacin and tetracycline (p<0.05). In BP strains, minimum inhibitory concentration (MIC) and minimum biofilm eradication concentration (MBEC) values against
oxacillin, vancomycin, and daptomycin were compared, and MBEC values were higher than MIC values. Moreover, MBEC50 values were observed to increase as biofilm mass increased. Daptomycin demonstrated superior biofilm eradication potential, especially in weak and moderate biofilms. These findings suggest that treatment strategies based solely on MIC values may be insufficient in infections caused by BP staphylococci and that MBEC analysis should be considered to guide more effective antimicrobial therapy.

Keywords

biofilm , Antibiotic Resistance , Staphylococcus , Catheter-related infections

Ethical Statement

This study was approved by the Non-Interventional Clinical Research Ethics Committee of Çukurova University Faculty of Medicine (03.04.2015, Decision No: 7).

Supporting Institution

This study was supported by the Çukurova University Rectorate Research Fund under the project number DKT-2016-7334.

Project Number

DKT-2016-7334

Kateter Örneklerinden İzole Edilen Stafilokoklar Tarafından Üretilen Biyofilmlere Karşı Antibiyotik Etkinliğinin İn Vitro Değerlendirilmesi

Abstract

Stafilokoklar, kateterle ilişkili enfeksiyonların en yaygın etkenlerindendir ve biyofilm oluşturma yetenekleri bu enfeksiyonların tedavisini zorlaştıran önemli bir virülans faktörüdür. Bu çalışmada, kan kateteri örneklerinden izole edilen Staphylococcus suşlarının antibiyotik direnç profilleri ile biyofilm oluşturma kapasiteleri in vitro olarak değerlendirildi. Toplam 65 izolatın antibiyotik duyarlılığı VITEK-2 otomatik sistemi ve sıvı mikrodilüsyon yöntemi ile belirlendi. İzolatların oluşturduğu biyofilm kütle miktarı kristal viyole boyama yöntemiyle değerlendirildi ve elde edilen optik dansite (OD) değerlerine göre sınıflandırıldı. İzolatların %54.8'inin biyofilm pozitif (BP) olduğu tespit edildi. BP suşlar, biyofilm negatif (BN) suşlara göre çoğu antibiyotiğe daha dirençli bulundu, bu fark siprofloksasin ve tetrasiklin için istatistiksel olarak anlamlı idi (p<0.05). BP suşlarda oksasilin, vankomisin ve daptomisine karşı minimum inhibitör konsantrasyonu (MİK) ve minimum biyofilm eradikasyon konsantrasyonu (MBEK) değerleri karşılaştırıldı, MBEK değerlerinin MİK değerlerine göre yüksek olduğu görüldü. Ayrıca, biyofilm kütlesi arttıkça MBEK50 değerlerinin de arttığı gözlemlendi. Özellikle zayıf ve orta dereceli biyofilmlerde daptomisinin eradikasyon potansiyelinin daha yüksek olduğu belirlendi. Bu bulgular, BP stafilokokların etken olduğu enfeksiyonlarda sadece MİK değerlerine dayalı tedavi stratejilerinin yetersiz kalabileceğini ve tedavinin daha etkili olarak yönlendirilebilmesi için MBEK analizlerinin dikkate alınması gerektiğini düşündürmektedir.

Keywords

biyofilm , Antibiyotik Direnci , Staphylococcus , katater ilişkili enfeksiyonlar

Ethical Statement

Bu çalışma, Çukurova Üniversitesi Tıp Fakültesi Girişimsel Olmayan Klinik Araştırmalar Etik Kurulu onayı (03.04.2015-Karar No: 7) ile gerçekleştirilmiştir.

Supporting Institution

Bu çalışma, Çukurova Üniversitesi Rektörlüğü Araştırma Fonu tarafından DKT-2016-7334 numaralı proje kapsamında desteklenmiştir.

Project Number

DKT-2016-7334

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