Generation of Methicillin-Resistant Staphylococcus Aureus Biofilm Infection in an Immunosuppressed Rat Model

Abstract

BackgroundMethicillin-resistant Staphylococcus aureus (MRSA) is a common pathogen responsible for many related infections, and immunosuppressed individuals are more susceptible. Its pathogenicity is associated with its virulence factors, resistance to antibiotics, and ability to form biofilm (BF). MRSA-BF infections in immunosuppressed patients pose great difficulties to clinical treatment.Material/MethodsThe study aimed to establish a model of MRSA-BF infection in rats with cyclophosphamide (CTX)-induced immunosuppression. For this, rats were administered CTX on days 1 and 4. White blood cells (WBC) were counted, then rats were inoculated with a clinical MRSA 17546 (t037) on day 5. Rats were sacrificed on days 6–10 and tissue samples were examined by scanning electron microscopy.ResultsUsing the dose of CTX: 150 (mg/kg) + 100 (mg/kg) is better than the other 2 programs as the survival rates of the immunocompromised rats were higher than in the other 2 immunosuppressive groups. The survival rate was not different between rats in the clean environment and in the SPF environment. However, the survival rate was affected by the sample acquisitions. Importantly, WBC counts started to decline on day 4, and then started to rise on day 9. Moreover, MRSA-BFs were formed earlier in immunosuppressed rats compared to the normal rats, as shown by scanning electron microscopy.ConclusionsThe study successfully established an immunosuppressed rat model of MRSA-BF infection, which provides methodological and data support for establishment of such animal models and is useful reference for related research. Our results may help further investigation of MRSA-BF infection.

Wound swabs versus biopsies to detect methicillin resistant Staphylococcus aureus in experimental equine wounds

“…Cultured bacteria were washed once with Dulbecco's phosphate buffered saline (DPBS) and suspended in 5% carboxymethylcellulose (CMC) in DPBS at the desired concentrations. Methicillin‐resistant Staphylococcus aureus is often suspended in CMC for application in animal models to increase the viscosity of the inoculum and prevent dripping 29 . Wounds were randomly assigned to be inoculated with 100 μl of 0, 5 × 10 8 , 5 × 10 9 or 5 × 10 10 colony‐forming units (CFU)/ml of a pure culture of MRSA (ATCC 43 300) suspended in 5% CMC.…”

“…Methicillin-resistant Staphylococcus aureus is often suspended in CMC for application in animal models to increase the viscosity of the inoculum and prevent dripping. 29 Wounds were randomly assigned to be inoculated with 100 μl of 0, 5 Â 10 8 , 5 Â 10 9 or 5 Â 10 10 colonyforming units (CFU)/ml of a pure culture of MRSA (ATCC 43 300) suspended in 5% CMC. Wounds were inoculated by pipetting 100 μl of CMC containing only MRSA directly onto the wound.…”

Antimicrobial and Biofilm-Preventing Activity of l-Borneol Possessing 2(5H)-Furanone Derivative F131 against S. aureus—C. albicans Mixed Cultures

“…While in the biofilm, cells intensively produce factors of virulence, induce horizontal genes transfers and remain inaccessible for antimicrobials and the immune system of the host due to a physical barrier formed by an extracellular matrix [ 11 , 12 , 13 , 14 , 15 ]. Consequently, rapid development of multiple resistances to antimicrobials occurs, as well as the acute infection transforms to persistent, chronic and recurrent infection [ 16 , 17 , 18 ].…”

WYBQ-4: a New Bactericidal Agent against Methicillin-Resistant Staphylococcus aureus

“…In addition, diseases caused by MRSA have high morbidity and mortality, and their treatments are extremely difficult. At present, as the pace of exploitation of new antibiotics is still slow, highly effective drugs against MRSA infection are urgently needed ( 6 ).…”