Biofilm‐associated infections are of great concern because they are associated with antibiotic resistance and immune evasion. Co‐colonization by Staphylococcus aureus and Streptococcus pneumoniae is possible and a threat in clinical practice.
We investigated the interaction between S. aureus and S. pneumoniae in mixed biofilms and tested new antibiofilm therapies with antioxidants N‐acetyl‐l‐cysteine (NAC) and cysteamine (Cys).
[A]dministration of 5 mg/ml of NAC nearly eradicated the S. pneumoniae population and killed nearly 94% of MSSA cells and 99% of MRSA cells in the mixed biofilms.
[R]esults identify NAC and Cys as promising repurposed drug candidates for the prevention and treatment of mixed biofilms by S. pneumoniae and S. aureus.
The burden of disease by S. pneumoniae is substantial as it is the main bacterial cause of community- acquired pneumonia, acute otitis media (AOM), bacterial meningitis, and a major cause of bacterial sepsis.
Pneumococcal vaccines have decreased the incidence of invasive pneumococcal disease (IPD) worldwide, but the emergence of non-vaccine serotypes, due to serotype replacement and capsular switch phenomena, is worrisome in most of the European countries.
In addition, the impact of pneumococcal vaccines against colonization of the nasopharynx seems to be moderate [not strong] in the pediatric population.
Staphylococcus aureus frequently colonizes the skin of the human population (> 30%) but can be found in the nasopharynx up to 80% of individuals…
[T]his pathogen can produce secondary episodes of bacterial pneumonia after influenza virus infection, which is a frequent trait shared with S. pneumoniae.
[E]pidemiological studies showed that up to 24% of patients were colonized by both species and that vaccination with the conjugate vaccine did not modify the nasopharyngeal carriage by S. aureus.
[S]everal evidences suggest that antioxidants compounds such as N-acetyl- l-cysteine (NAC) and cysteamine (Cys) might have the potential as antimicrobial drugs against individual biofilms of certain species…
To this date, the identification of S. aureus strains associated with resistance or even tolerance to NAC [or] Cys has not been shown.
In this work, we describe the antimicrobial effect of both antioxidants against mixed biofilms of S. aureus and S. pneumoniae, demonstrating that the pneumococcal population was practically eradicated with only 0.5 mg/ml of NAC…
[T]reatment with NAC of mixed biofilms does not disperse the bacterial cells within the biofilm. This is an advantage in clinical practice as the not dispersing effect avoids the potential colonization of a new habitat within the host.
This confirms that the use of alternative therapies against polymicrobial biofilms such as antioxidants is necessary.