Phenotypic and Molecular Detection of Biofilm Formation in Methicillin-Resistant Staphylococcus Aureus Isolated from Different Clinical Sources in Erbil City

Antibiotic resistance, biofilm formation, and molecular epidemiology of Staphylococcus aureus in a tertiary hospital in Xiangyang, China

Staphylococcus aureus is a common clinical pathogen that causes various human infections. The aim of this study was to investigate the antibiotic susceptibility pattern, molecular epidemiological characteristics, and biofilm formation ability of S. aureus isolates from clinical specimens in Xiangyang and to analyze the correlation among them. A total of 111 non-duplicate S. aureus isolates were collected from the Affiliated Hospital of Hubei University of Arts and Science. All isolates were tested for antibacterial susceptibility. Methicillin-resistant S. aureus (MRSA) was identified by the mecA gene PCR amplification. All isolates were analyzed to determine their biofilm-forming ability using the microplate method. The biofilm-related gene was determined using PCR. SCCmec, MLST, and spa types of MRSA strains were performed to ascertain the molecular characteristics. Among the 111 S. aureus isolates, 45 (40.5%) and 66 (59.5%) were MRSA and MSSA, respectively. The resistance of MRSA strains to the tested antibiotics was significantly stronger than that of MSSA strains. All isolates were able to produce biofilm with levels ranging from strong (28.9%, 18.2%), moderate (62.2%, 62.1%), to weak (8.9%, 19.7%). Strong biofilm formation was observed in MRSA strains than in MSSA strains, based on percentages. There were dynamic changes in molecular epidemic characteristics of MRSA isolates in Xiangyang. SCCmecIVa-ST22-t309, SCCmecIVa-ST59-t437, and SCCmecIVa-ST5-t2460 were currently the main epidemic clones in this region. SCCmecIVa-ST5-t2460 and SCCmecIVa/III-ST22-t309 have stronger antibiotic resistance than SCCmecIVa-ST59-t437 strains, with resistance to 6 ~ 8 detected non-β-lactam antibiotics. The molecular epidemic and resistance attributes of S. aureus should be timely monitored, and effective measures should be adopted to control the clinical infection and spread of the bacteria.

SMR peptide antagonizes Staphylococcus aureus biofilm formation

The emergence and international dissemination of multi-drug resistant Staphylococcus aureus (S. aureus) strains challenge current antibiotic-based therapies, representing an urgent threat to public health worldwide. In the U.S. alone, S. aureus infections are responsible for 11,000 deaths and 500,000 hospitalizations annually. Biofilm formation is a major contributor to antibiotic tolerance and resistance-induced delays in empirical therapy with increased infection severity, frequency, treatment failure, and mortality. Developing novel treatment strategies to prevent and disrupt biofilm formation is imperative. In this article, we test the Secretion Modification Region (SMR) peptides for inhibitory effects on resistant S. aureus biofilm-forming capacity by targeting the molecular chaperone DnaK. The dose effect of SMR peptides on biofilm formation was assessed using microtiter plate methods and confocal microscopy. Interaction between the antagonist and DnaK was determined by immune precipitation with anti-Flag M2 Affinity and Western blot analysis. Increasing SMR peptide concentrations exhibited increasing blockade of S. aureus biofilm formation with significant inhibition found at 18 µM, 36 µM, and 72 µM. This work supports the potential therapeutic benefit of SMR peptides in reducing biofilm viability and could improve the susceptibility to antimicrobial agents.IMPORTANCEThe development of anti-biofilm agents is critical to restoring bacterial sensitivity, directly combating the evolution of resistance, and overall reducing the clinical burden related to pervasive biofilm-mediated infections. Thus, in this study, the SMR peptide, a novel small molecule derived from the HIV Nef protein, was preliminarily explored for anti-biofilm properties. The SMR peptide was shown to effectively target the molecular chaperone DnaK and inhibit biofilm formation in a dose-dependent manner. These results support further investigation into the mechanism of SMR peptide-mediated biofilm formation and inhibition to benefit rational drug design and the identification of therapeutic targets.