No Correlation between Biofilm-Forming Capacity and Antibiotic Resistance in Environmental Staphylococcus spp.: In Vitro Results

Abstract

The production of biofilms is a critical factor in facilitating the survival of Staphylococcus spp. in vivo and in protecting against various environmental noxa. The possible relationship between the antibiotic-resistant phenotype and biofilm-forming capacity has raised considerable interest. The purpose of the study was to assess the interdependence between biofilm-forming capacity and the antibiotic-resistant phenotype in 299 Staphylococcus spp. (S. aureus n = 143, non-aureus staphylococci [NAS] n = 156) of environmental origin. Antimicrobial susceptibility testing and detection of methicillin resistance (MR) was performed. The capacity of isolates to produce biofilms was assessed using Congo red agar (CRA) plates and a crystal violet microtiter-plate-based (CV-MTP) method. MR was identified in 46.9% of S. aureus and 53.8% of NAS isolates (p > 0.05), with resistance to most commonly used drugs being significantly higher in MR isolates compared to methicillin-susceptible isolates. Resistance rates were highest for clindamycin (57.9%), erythromycin (52.2%) and trimethoprim-sulfamethoxazole (51.1%), while susceptibility was retained for most last-resort drugs. Based on the CRA plates, biofilm was produced by 30.8% of S. aureus and 44.9% of NAS (p = 0.014), while based on the CV-MTP method, 51.7% of S. aureus and 62.8% of NAS were identified as strong biofilm producers, respectively (mean OD570 values: S. aureus: 0.779±0.471 vs. NAS: 1.053±0.551; p < 0.001). No significant differences in biofilm formation were observed based on MR (susceptible: 0.824 ± 0.325 vs. resistant: 0.896 ± 0.367; p = 0.101). However, pronounced differences in biofilm formation were identified based on rifampicin susceptibility (S: 0.784 ± 0.281 vs. R: 1.239 ± 0.286; p = 0.011). The mechanistic understanding of the mechanisms Staphylococcus spp. use to withstand harsh environmental and in vivo conditions is crucial to appropriately address the therapy and eradication of these pathogens.

Relationship between Biofilm-Formation, Phenotypic Virulence Factors and Antibiotic Resistance in Environmental Pseudomonas aeruginosa

“…The lack of molecular biological methods (PCR, MLST, sequencing) employed is a considerable limitation of the study; therefore, we do not have information regarding the genetic origin (e.g., the clonal lineage) of the isolates, the presence and expression levels of the biofilm, virulence and/or resistance genes, or the genotype-phenotype relationship in PA. As the regulation of the cellular and metabolic processes (e.g., expression of virulence factors) may differ considerably among genera, the generalization of results among different bacteria is also limited [81]. For example, during a similar biofilm-related study on environmental Staphylococcus spp., no correlation was observed between MDR and biofilm formation, while a significant association was found between rifampicin resistance and strong biofilm-producers [82]. ; Within its limitations, our study has provided additional data on the relationship between antibiotic resistance, biofilm-forming capacity, and other relevant virulence factors.…”

Anti-Biofilm Effect of Bacteriophages and Antibiotics against Uropathogenic Escherichia coli

“…We did not investigate the genetic determinants of the formation of bacterial biofilms, but this would be essential to fully understand bacterial biofilms. Highly resistant bacterial strains are not necessarily the strongest biofilm formers [ 27 , 28 ]. For instance, the ESBL-positive 01032UR strain described in our study was resistant to amoxicillin, amoxicillin–clavulanic acid, cefotaxime, and ceftazidime.…”

Lack of Direct Correlation between Biofilm Formation and Antimicrobial Resistance in Clinical Staphylococcus epidermidis Isolates from an Italian Hospital

“…However, the existence of a direct relationship between antibiotic resistance and the extent of slime/biofilm formation in S. epidermidis clinical strains remains a controversial issue. Indeed, some works have reported a higher incidence of antibiotic resistance among exopolysaccharide-forming S. epidermidis clinical strains, while other studies have displayed no difference in resistance rates between the biofilm-producer and non-producer S. epidermidis isolates [8,[39][40][41][42][43].…”