# Management of Scalp Biofilm in Local Dermatosis: From In Vivo Visualization to Optimal Treatments
## 4 Discussion
There were variations in the ability of previous cutaneous _Propionibacteriumum_ species to generate extracellular polysaccharides or pili-like structures, likely resulting from disparities in the bacteria's genomes [36]. _P. acnes_ strains 266 and KPA171202, cultivated in liquid medium, lacked extracellular structures based on polysaccharides, while _P. avidum_ strains were characterized by the presence of abundant polysaccharide coatings surrounding the cells [36]. A novel extracellular antioxidant protein, RoxP, was recently identified in _C. acnes_, and its expression seems to be specific to certain strains. RoxP is extensively released into the liquid culture medium and may play a beneficial role for both host cells and _C. acnes_ in the skin [37; 38]. In addition, the biofilm matrix of the acne-causing _C. acnes_ RT5, one of the pathogenic subtypes of acne, seems to consist primarily of polysaccharides. The main matrix components are present in the following proportions: 62.6% polysaccharides, 9.6% proteins, 4.0% DNA, and 23.8% other compounds (including porphyrin precursors and others) [35]. The planktonic form of _S. aureus_ does not appear to be resistant to disinfectants, compared to other bacteria, but it can be one of the most resistant when adhered to a surface [39]. _S. aureus_ has the ability to generate a multi-layered biofilm enclosed within a glycosylx with varied protein expression throughout. This results in the formation of at least two types of biofilms: ica-dependent biofilms, facilitated by polysaccharide intercellular adhesin (PIA)/poly-N-acetyl-1,6-\(\beta\)-glucosamine (PNAG), and ica-independent biofilms, facilitated by proteins [40]. Additionally, the extracellular matrix of clinical _S. aureus_ biofilms is composed of cytoplasmic proteins that interact with the cell surface in response to a declining pH. Sensitive adaptation to the environment enhanced _S. aureus_'s resistance and biofilm formation capabilities [41]. _Malassezia_ is a genus known for yeasts with a thick cell wall [42]. Dandruff and seborrheic dermatitis are among the main skin disorders attributed to _Malassezia furfur_[43]. It has also been documented in the literature that _M. furfur_ has the ability to form biofilms [44]. Moreover, in more severe cases, this species can cause fungemia associated with intravenous catheters in immunocompromised patients [45]. The biofilm exhibits distinct physiological and phenotypic traits compared to planktonic cells, including increased efflux pump activity and alterations in membrane/matrix composition [46]. The arrangement of blastoconidia into clusters within the _Malassezia_ and _Candidida_ biofilm, forming multi- or monolayers and generating the extracellular matrix, is likely to create a barrier against drugs. However, the biofilm's resistance to drugs cannot solely be attributed to this physiological barrier. For instance, the natural selection of biofilm cells through the apoptosis of sub-lethally damaged cells, as well as the increased expression of efflux pumps encoded by CDR1, CDR2, and MDR1 genes, may also contribute to the biofilm's resistance [28; 47; 48]. Investigation into scalp biofilm properties are limited. The biofilms of _C. acnes_, _S. aureus_, and _Malassezia_ typically form in distinctive environments, such as on prosthetic joint implants or in skin glands and hair follicles, which have different physiological features from other cutaneous tissues [49; 50]. In addition, the biofilm phenotype is the result of changes in the expression of numerous genes [51], and the process begins when microbial cells adhere to the surface [52]. Therefore, it is essential to study natural biofilms to comprehend their extracellular matrix. Indeed, it is still questionable as to whether we can extrapolate the molecular mechanism of planktonic cells to biofilms. Scalp skin biofilms grow predominantly in lipid-rich areas around hair follicles and associated skin folds. They can cause severe damage to the scalp epidermis via partial hypoxia states [53].