## 2 Wound Healing
### Prominent Infection and Healing--Current Treatments  
Prominent infections are often mentioned as the most common impediment to wound healing, especially in the case of chronic wounds. As already mentioned, chronic wounds are highly prone to develop serious infections given that an open wound is a favorable niche for microbial colonization [15]. Wound infection is characterized by the colonization of pathogenic microorganisms, usually bacteria, capable of developing colonies in the wound site. Consequently, while the healing process is delayed, the wound becomes increasingly impenetrable by the antimicrobial agents [15]. Another consequence associated with wound infection is oxidative stress, which also retards the physiological healing process. Chronic infections frequently require hospitalization of patients and the infection is responsible for high rates of morbidity and mortality. Although the micro profile varies from patient to patient, infection in chronic wounds is frequently polymicrobial. Studies have shown that the most frequent microorganisms include _Staphylococcus aureus_ and methicillin-resistant _S. aureus_ in the initial stages of chronic wounds, and _Escherichia coli_ and _Pseudomonas aeruginosa_ in later stages [2; 9]. There are many approaches toward the treatment of wound infections that simultaneously improve the healing process. The priority is to stop the progression of the infection using antimicrobial agents such as antibiotics. Different antibiotics are available for chronic wound treatment, but the selection of the adequate antimicrobial compound must be pondered, based on the pathogenic organisms and the antimicrobial susceptibility patterns. Although antibiotics have significantly improved human health, many resistances to the antibiotics such as ampicillin, gentamicin, and ciprofloxacin (first-line antibiotics) are developed in the case of an inappropriate choice of the antibiotic, a shorter or extended application, or even a low concentration of the antimicrobial agent [9; 23]. Consequently, infected chronic wound control has become an increasing health problem and has made it difficult to select appropriate antibiotics for treatment. In recent years, the resistance of bacteria to antibiotics has become more and more evident, which is a cause for concern in the health sector [24]. Because antimicrobial resistance is on the rise, there is an emerging demand from research around the world to explore new alternatives. Several recent developments in wound care have focused on integrating different antimicrobial agents in combined physical current therapies, for chronic wound infections [24]. Due to all possible impairments on the healing process, there are different available treatments for chronic wounds--from the traditional wound care management to the new and innovative therapies developed recently [9; 22]. As with acute wounds, the debridementand the use of wound dressings in chronic wounds are considered a traditional and crucial method of local wound management in order to minimize infection and remove excess exudate and foreign material from the wound bed [8]. Debridement can also be performed using negative pressure therapy, which consists of the removal of exudates by vacuum devices [25]. Another approach for local wound management is hyperbaric oxygen therapy, which increases the production of growth factor and collagen and reduces the presence of pro-inflammatory enzymes [26]. For the same purpose, electrical stimulation consists of current pulses of electromagnetic energy. As regards relevance to improve the healing process, electrical stimulation can increase fibroblasts stimulation and enhance collagen production. In order to improve wound management further, new therapies have been recently proposed by the scientific community, such as ultrasounds. Ultrasound have shown to be able to reach deep-seated tissues due to being highly orienting and low scattering.