Abstract
Iron is a limiting factor in such a condition that usually is sequestered by the host during polymicrobial infections of Pseudomonas aeruginosa and Staphylococcus aureus. This study aimed to investigate the interaction of S. aureus and P. aeruginosa, which alters iron-related sigma factors regulation and antibiotic resistance. The antibiotic resistance of P. aeruginosa and S. aureus was investigated in a L929 cell culture model. The expression level of pvdS, hasI (P. aeruginosa sigma factors), and sigS (S. aureus sigma factor) genes was determined using Quantitative Real-Time PCR. pvdS and hasI were downregulated during co-culture with S. aureus, while the susceptibility to carbapenems increased (p-value < 0.0001). Also, there was a direct significant relationship between resistance to vancomycin with sigS. Regarding the findings of the current study, iron-related sigma factors of P. aeruginosa and S. aureus play a role in induction susceptibility to various antibiotics, including carbapenems and vancomycin.
Highlights
As the skin integrity is lost, the subcutaneous skin layer provides a suitable condition for colonization, wound infection, and biofilm formation[1]
This study aimed to determine how the iron-related extracytoplasmic function sigma factors (ECF) sigma factors would alter during S. aureus and P. aeruginosa interaction and how this alteration influenced the antibiotic resistance of persisters and wild-type isolates
A cell line-based model was developed to investigate the viability of S. aureus (SA-1) in co-culture with four clinical strains of P. aeruginosa (PA-1, PA-2, PA-3, and PAO1) in wound infections (Table 3)
Summary
As the skin integrity is lost, the subcutaneous skin layer provides a suitable condition (moisture, temperature, and nutrients) for colonization, wound infection, and biofilm formation[1]. Microorganisms develop different mechanisms, such as siderophores and heme assimilation factors, to acquire iron from the environment. Staphylococcus aureus and Pseudomonas aeruginosa, as dominant microorganisms involved in the wounds’ polymicrobial infections, develop different strategies to acquire iron, including pyoverdine and pyochelin in P. aeruginosa and Isd proteins in S. aureus. In such a situation, due to iron limitation, S. aureus and P. aeruginosa shift to heme and hemoglobin to provide iron through hemophores[4,5]. The iron acquisition is regulated by extracytoplasmic function sigma factors (ECF), including hasI and pvdS in P. aeruginosa. ECF sigma factors regulating iron metabolism may play a role in antibiotic resistance during c oinfections[6,7]. Overproduction of efflux pumps such as MexAB-OprM and reduced expression of porins including OprD lead to resistance to c arbapenems[15,16,17]
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