Together with impetigo, a pathologic skin condition related to abscesses and often found in children, the immunocompromised and in other populations living under conditions of poor hygiene, skin abscesses are among the most common soft tissue infections. The pathogenesis of the various types of abscesses (eg, furuncles, carbuncles, recurrent furunculosis, superficial and bullous impetigo) and their etiologic agents are considered in detail by other authors.¹,²,³ But overall, the most frequent of these are bacteria such as Staphylococcus aureus, group A streptococci (with nephritogenic strains causing special problems), and anaerobic bacteria, either in pure culture or mixed with coliforms, especially in the perineal region. Because general preventive measures against these primary skin infection conditions usually cannot be taken, apart from good hygiene practices, only therapy of already manifest infections is required (or possible), usually by incision and drainage or—under certain conditions—with antibiotics. In some of these cases, such as during or following drainage, antiseptics can be used to reduce the microbial load around the infection/intervention area to provide an advantage to the immune system in resolving the infection, reduce the risk of cross-infection to other areas of the skin, or to reduce the risk of secondary infections. Any example is the use of hydrogen peroxide for this that can aid in cleaning the wounded area and reducing the microbial load. Prevention of recurrent furuncles (or boils) has often been achieved by eradication of staphylococcal nasal carriage in the patient with mupirocin or chlorhexidine digluconate (CHG) or oral antibiotics such as clindamycin.⁴ But the successful use of antiseptics in these situations, as for antibiotics, can be variable depending on the patient/treatment.

Antisepsis has a place in the prevention of impetigo, which is a contagious condition. Although until the 1980s,
mercurochrome, an organic mercury compound, was regarded as the antiseptic of choice for this purpose, its use, at least for large skin surface areas, is discouraged today because of toxicologic considerations.⁵ Instead, aqueous or detergent-containing preparations of CHG, povidone-iodine, or mupirocin are most commonly used. Topical (localized) or in more severe cases oral or parenteral antibiotics are also used.¹,⁶

This condition represents a superficial, erythematous inflammation of the skin that must be distinguished from infections of deeper tissues such as subcutaneous fat, fascia, and muscle. Sometimes, these tissues may be affected by extension of a superficial cellulitis. Underlying disorders such as diabetes mellitus, preceding trauma, other skin infections (eg, varicella), lymphedema of the legs, genetic disposition such as in familial Mediterranean fever, skin lesions, and defects in cellular or humoral immunity are also known risk factors for cellulitis.¹,²,³ The most frequent forms and causes for cellulitis are as follows:

An analysis of these infections with respect to prevention reveals that treatment of underlying disorders in the host, whenever possible, and reducing external risk factors such as contaminated bathing water, whirlpools, and hydrotherapy devices, are probably the most effective prophylactic measures achievable. Antiseptic measures can play a supportive, although very limited role in the treatment of superficial skin lesions.

Puncture wounds may create local infection problems if they originate from contaminated sharps such as butcher’s knives or pointed objects such as nails and thorns. For example, puncture wounds occur most commonly in children’s feet during warm weather.⁷,⁸ Other risks come from deliberate puncture wounds such as in tattooing and intravenous drug use. These wounds can lead to cellulitis, soft tissue infection, osteomyelitis, and tetanus. Although a wide range of microorganisms can be associated with these infections (due to the nature/source of the trauma), Streptococcus species, P aeruginosa, and S aureus are often cited as the most frequent causative agents.⁸,⁹ More severe infections can result with bacteria such as atypical Mycobacterium and Clostridium tetani (tetanus).

Prevention of infection and treatment of the fresh wound consists of cleaning with an iodophor or alcohol antiseptic, surgical intervention for search and removal of any residual foreign body, and tetanus prophylaxis. In fresh (<6 h) wounds, antibiotic prophylaxis is not routinely indicated, unless the patient is at a higher risk for infection (eg, diabetics or when the wound is found to be infected).

The management of bite wounds is very similar and has also been extensively reviewed elsewhere.¹⁰,¹¹,¹² With respect to frequency and severity of infections after bites, some facts have been established that may help to prevent complications. Dog bites account for the majority (approximately 70% to 80%) of animal bite wounds, and it is estimated that 10% to 20% of them become infected,
although this may range as high as 50% in some situation.¹⁰,¹³ There is some evidence that the rates of infection are lower with human bites than with dog bites, but the cat bites can be much higher.¹³ Due to increases in tourism worldwide and exchange or exotic animals as pets, many cases of infection (in some cases serious) linked to other animal bites, for example with bats that are often associated with outbreaks of Ebola and coronaviruses.¹⁴,¹⁵ Equally, our knowledge of the risks associated with tick-borne infections has increased in the last 10 years (eg, with Lyme disease and Borrelia burgdorferi).¹⁶ But in general, the main causative organisms of bite wound infections are Pasteurella, α-hemolytic streptococci, various Staphylococcus species, Enterococcus, Neisseria, and Corynebacterium, independent of the source animal.¹⁰,¹²,¹³,¹⁵ In bites of cats and cat-like predatory animals, the incidence of infection can greater than 50% and may involve not only skin and soft tissues but also bones and joints. The Pasteurella multocida is the pathogen most frequently isolated (>50%). A wide range of other bacteria have also been identified, especially anaerobes such as Propionibacterium and Fusobacterium. Although trivial wounds do not require antibiotic prophylaxis, this is recommended for more severe wounds, especially if hands and joints are involved or if a high risk of infection is suspected.¹⁰,¹¹,¹³,¹⁵ Clearly, antibiotics would not be effective in high-risk cases for virus infection (eg, with bats and animals suspected to have rabies). In any case, wound irrigation with soap/water, a saline solution or an antiseptic such as with alcohol, CHG or Povidone-Iodine (PVPI), debridement (if applicable), and tetanus prophylaxis are often used. Depending on the epidemiologic situation, rabies prophylaxis must be considered, especially as many countries no longer have recommended rabies vaccination due to low risks of infection in those countries, but this will not apply when travelling outside of those countries. Although these initial steps can be effective, subsequent signs of infection in the wound (such as swelling, redness, and pain) are indicative of the need for further intervention.

Infections after occlusion bites (when teeth break into the skin) and clenched-fist injuries, as happen when a person’s fist strikes another person’s teeth, are distinguished on the basis of their outcome and causative agents. Occlusion bites are most often infected by S aureus, Eikenella corrodens, H influenzae, and oral anaerobic bacteria, whereas the most serious clenched-fist injuries are usually infected by anaerobic bacteria, some of them producing β-lactamase, and by E corrodens (25%). In addition to the previously mentioned measures, antibiotic prophylaxis is necessary to prevent deep-space infection, septic arthritis, and osteomyelitis; patients with clenched-fist injuries require hospitalization and the attention of a hand surgeon.

Although antisepsis is not a key issue in the prevention of bite wound infections, some authorities have advocated treatment of fresh bite wounds with a solution of 0,1% benzalkonium chloride or with 56% to 70% ethanol instead of or in addition to the usual cleansing procedure with soap or detergent and water or only with saline.¹⁷,¹⁸,¹⁹ Recommended preparations have also included a combination formulation of povidone-iodine and ethanol (Betaseptic^®) and 0.1% to 0.2% polyhexanide, a polyhexamethylene bisguanidine for all kinds of traumatogenic wounds.¹⁹,²⁰

Decubital ulcers are skin ulcerations caused by prolonged pressure resulting in ischemic necrosis of the skin and underlying soft tissue. They are common in patients who, for various reasons, are not mobile enough to allow their pressurized body parts to recover from local ischemia. Malnutrition, incontinence, and low concentration of serum albumin may aggravate the condition. Complications arising from these skin lesions are cellulitis, soft tissue necrosis, osteomyelitis in adjacent bones, and systemic infection. The infectious flora is usually a mixed flora of aerobic and anaerobic bacteria, but differentiation between colonization and infection may be difficult. Bacteria most commonly isolated are staphylococci, streptococci, enterobacteria, and a range of anaerobic species.

The most important preventive measure is to remove the pressure from the affected skin area by special mattresses and beds ranging from egg-crate foam and automatic mattresses to turning or fluidized beds. Physiotherapy and massage increase local perfusion. High-calorie nutritional preparations and parenteral amino acid mixtures supplement protein loss from permanent wound secretion. Administration of antibiotics is considered necessary only when signs of tissue or systemic infection occur. Surgical debridement may be necessary in some cases, followed by plastic surgery. The role of antisepsis is limited to the attempt to delay heavy bacterial colonization of the wound. Aqueous povidone-iodine solutions or ointments are most commonly applied. In some countries, tetrachlorodecaoxide (Oxoferin^®) was also used for many years for both prevention and eradication of bacterial colonization and, because of its stimulating effect on epithelial granulation, as a preparation for the base of ulcers for skin transplantation.²¹ Other examples include the use of advanced, including biocide-impregnated dressings such as those containing silver, CHG, and polyhexamethylene biguanides (see chapters 73 and 74).²² Although the benefits of many of dressings or topical treatments in these cases can range considerably, advances in the development of optimum biocide delivery, effectiveness, and novel application are areas of recent research, in particular as alternatives to combat emerging antibiotic resistance trends.²³

Since the onset of surgery, the surgical wound has always been recognized as a site of increased infection risk (see chapter 43). The pathogenesis, epidemiology, and prevention of surgical site infection (SSI) and the factors determining these risks have been well studied since Joseph Lister, at the latest, but exhaustively so during the 40 years to enable surgeons to apply continuously improving surgical techniques without jeopardizing the results of
their work. Excellent guidelines and recommendations for prevention of SSI have been published,²⁴,²⁵ that have continued to build on previous versions.²⁶ In addition, the Centers for Disease Control and Prevention (CDC) had developed a system of standardized surveillance criteria for defining SSI²⁷ that have been widely used. According to this CDC system, SSIs are classified into superficial incisional, deep incisional, and organ/space infections. Similar classification systems are used worldwide but can vary from country to country.²⁵ Surveillance of SSI rates are recommended as an essential part of the World Health Organization (WHO) guidelines to reduce SSIs, as well as being mandatory (eg, in the United Kingdom) or voluntary in different countries.²⁵,²⁸,²⁹

The literature on this subject cannot be reviewed in full here and is further considered in chapter 43. But a few facts should be recalled and explained to define the role of antisepsis within the range of other preventive measures or factors influencing infection risk. SSIs are the most common of reported health care-acquired infections, are a major cause of morbidity and mortality, and a significant cost burden.²⁵,³⁰ In the United States alone, it is estimated that approximately 2% of surgical procedures are associated with an SSI, and these rates can range for facility to facility and country to country. According to various sources,²⁵,³¹,³² the most frequent causative agents of SSI are bacteria including S aureus (approximately 30%), coagulase-negative staphylococci (approximately 12%), Escherichia coli (approximately 9%), Enterococcus faecalis (6%), P aeruginosa (approximately 5%), Enterobacter species (4%), and Klebsiella species (4%). Other bacteria and fungi (especially Candida albicans) are also frequently implicated. It is generally accepted that the main source of this flora is the patient.²⁴,²⁵,³³ Apart from specific carrier dispersers (such as those carrying S aureus in the nares), surgical personnel are regarded as a less important source if the rules of good surgical practice are adhered to.³⁴

Among the risk factors associated with SSI are patientrelated (ie, patient characteristics), procedure-related ones (ie, operative characteristics), and postoperative characteristics (see chapter 43). Examples of the former are patient age, nasal carriage of S aureus, underlying diseases and pathologic conditions such as obesity and diabetes, presence of infection at other sites, malnutrition and glucose levels, the length of the preoperative hospital stay, and others.²⁴,²⁵ Examples of operative characteristics include type of procedure, such as orthopedic, breast, or heart surgery, with or without implanted foreign material; duration of the surgical procedure, whether it is an emergency or elective operation; hair removal; blood transfusion; and antibiotic prophylaxis.²⁴,²⁵,²⁶,³³

The risk for development of an infection can be affected by the quality of the surgical technique (which is often difficult to assess objectively) and by the degree of microbial contamination of the surgical site during the operation. Based on the latter, the National Academy of Sciences and the National Research Council³⁵ developed a widely accepted classification of surgical wounds that is used worldwide,²⁴,²⁵ stratifying them into four major categories:

There is a clear correlation between the class of surgical wound and the postoperative infection rate,²⁴,²⁵,³²,³⁶,³⁷,³⁸ which ranges for the four classes between 0.2% to 2.9%, 0.9% to 3.9%, 1.3% to 8.5%, and 2.1% to 48%, respectively (see chapter 43). Among all these risk factors, the patient’s own colonizing and, even more, the infecting microflora play an important role, as does the flora of the environment surgical team.²⁵ This has been considered in attempts to minimize the infection risk by including relevant recommendations for the management of both infected patients or staff members and for antiseptic measures to reduce the level of colonizing microbial flora that might reach the surgical site (chapter 43).

The latest guidelines for the prevention of SSI²⁴,²⁵ provide recommendations that are categorized based on existing scientific data, theoretic rationale, and applicability. For example, the CDC category IA and IB recommendations are regarded as effective by experts in the fields of surgery, infectious diseases, and infection control based on the quality of scientific evidence suggesting net clinical benefits. Category II recommendations have, based on the review committee, less supporting scientific data than for category I in the balance between clinical benefits and harms. For some practices, no recommendation is given because the available scientific evidence is not considered sufficient, or there is lack of consensus as to their efficacy.²⁵ But the subjectivity of some of these recommendations is highlighted in a comparison between international recommendations based on the same data
review.²⁴,²⁵ Examples include the use of antimicrobial sutures and the benefit/harms balance of the identification of underlying conditions and/or infections. Others seem to make practical sense, such as the identification of personnel with potentially transmissible infection (eg, such as the carriage of S aureus in the nares) should be identified or encouraged to report the condition, and policies should be developed that allow work restrictions and require clearance to resume work after an illness that required work exclusion.

For antiseptic measures at the incisional site or the team’s hands, there are many data on the antimicrobial efficacy of various agents on the skin (see chapters 42 and 43), but the clinical effects of optimum preoperative skin antisepsis on the risk of SSI remain the subject of debate. Nevertheless, use of an appropriate antiseptic agent is recommended for preparation of the incision site, which has been previously washed and cleaned to remove gross contamination.²⁴,²⁵ Overall, the guidelines highlight the use of alcohol-based antiseptics that may or may not include CHG for presurgical, intraoperative skin preparation (see chapter 43). Other widely used biocides include CHG and iodine (eg, iodophor) products, but alcohols are generally found to be more effective. No one type of preoperative skin preparation has been shown consistently to reduce SSI rates, despite studies that shows differences in their safety and effectiveness.³⁹ But overall, the selection of a product will depend on the needs of the surgical procedure on the patient (eg, the location on the body) and the surgical staff. The timing and method of application depends on the specific and approved labeled claims of the preoperative skin preparation product.

Likewise, the recommendations for hand antisepsis of the surgical team are recommended using an appropriate antiseptic, despite the subsequent use of surgical, sterile gloves.²⁴,²⁵ The recommended surgical scrub procedures require that staff first remove any jewelry (eg, rings and watches), clean under the fingernails with water, and then apply an appropriate antiseptic (preferably with a biocide that presents with persistent activity such as CHG) in accordance with manufacturer’s instructions.⁴⁰,⁴¹ For hand washes, this includes washing the hands and forearms thoroughly with an antimicrobial soap, followed by rinsing and drying prior to donning gloves. For hand rubs, it is recommended that the hands are first washed with a nonantimicrobial soap, rinsed, and dried and then applying the alcohol solution to hands and rubbing into the hands and forearms; the hands should be allowed to dry before donning gloves. Antiseptics should be used as recommended by the manufacturer (2-6 minutes, in general), with no need for arbitrary extended contact time recommendations that were often cited in the past.²⁶ It is equally important to follow aseptic practices following hand washing/scrubbing in gowning (including donning of sterile gloves) and subsequent surgical practices to reduce cross-contamination risks.³⁴

For skin and hand antisepsis, only a few groups of chemical agents are suitable, some of them only in combination with alcohols:

Of these, alcohols are by far the fastest acting and most efficacious.²⁴,²⁵,⁴⁰,⁴¹,⁴²,⁴³ Almost exclusively, the short-chain, aliphatic alcohols—ethanol, isopropanol, and in Europe, n-propanol—are used for skin and hand antisepsis (see chapters 19 and 42). They have excellent activity against bacteria, fungi, and enveloped viruses. Against nonenveloped viruses such as enteroviruses, including picornavirus and hepatitis A virus, their activity is less pronounced and limited to high concentrations (>90% volume per volume [vol/vol]) of ethanol.⁴⁴,⁴⁵ Antimicrobial activity against these viruses is often considered less important because viruses are not members of the resident skin flora and are not typically cited as become sources of SSIs but may in some cases be associated with cross-infection in particular for blood-borne pathogens.⁴⁶ In addition, alcohols are not effective against bacterial spores and instances of alcohol contamination with spore-forming pathogens or the carriage of spores in health care worker hands have been reported,⁴⁷ suggesting the use of products that are known to be free of spores or the use of the physical removal of spores (by washing) have been recommended. Alcohols are also flammable, and this may be a disadvantage for their use in the operating room and requires special considerations for storage.³⁴ Furthermore, the surgical team must ensure that no alcohol residues are left on the skin and under the patient to avoid burns when a thermocautery is used, and to prevent postoperative skin necrosis at the contact surface when the patient is left lying in a pool of alcohol.

There is a clear association between the alcohol species and antimicrobial efficacy, with n-propanol being the most active, followed by isopropanol and ethanol (see chapters 19 and 42).⁴²,⁴³ The activity also depends on the concentration. The strongest and fastest action is seen with n-propanol and isopropanol at concentrations of 100%, and with ethanol at concentrations of 85% to 95% vol/vol. The traditional belief that the best activity of ethanol is achieved at 77% vol/vol is true only for dry bacteria,⁴²,⁴⁸ and this will also depend on the formulation of the alcohol product (see chapter 19). Skin bacteria are never considered dry. To be effective in the discussed areas of application, alcohol concentrations (here, always vol/vol) should typically not fall below 60% with n-propanol, 80% with isopropanol, and 90% with ethanol. This opinion is based on the observation⁴⁹ that the efficacy of isopropanol
against the resident skin flora of hands is comparable with that of n-propanol 60. At 70%, the bacterial reduction was considered significantly less. Likewise, with ethanol 85%, it was shown that even this high concentration was significantly less effective than 80%, although significantly more effective than isopropanol at 70%.⁵⁰ Only at 95% was the activity of ethanol comparable with that of n-propanol 60%, but these results may depend not only on the specific alcohol concentration but also the overall formulation and demonstrated effectiveness of the specific antiseptic. It must be admitted, that the antimicrobial activity of n-propanol 60% was arbitrarily chosen as a reference for a European Standard,⁵¹ and there are no data to prove its clinical superiority in terms of a reduced rate of SSI.

In Table 44.1, the antibacterial efficacy of n-propanol 60% vol/vol is demonstrated for preoperative incision site antisepsis. Biopsy and cylinder scrub samplings were taken before the alcohol had been swabbed for exactly 1 minute onto the abdominal skin of recently deceased patients. After this procedure, samples were taken again at both points of time immediately and after complete drying, which extended the total disinfection time to 2 to 3 minutes.⁵² It can be seen that bacterial reduction by the alcohol is significantly associated with the disinfection time and that the antiseptic effect on anaerobic bacterial flora is less pronounced when the biopsy method is used, which samples the deeper anaerobic flora more effectively. This difference was not considered significant.

From very sebaceous areas such as scalp and forehead, the deep-lying skin flora is much more difficult to reduce. Sixty percent vol/vol n-propanol achieved a 2.1 log reduction of aerobic flora on the skin surface but only a 1.4 log reduction at depth, and propionibacteria were specifically reduced only by 0.6 log.⁵³ The corresponding values for isopropanol 60% vol/vol were 0.8, 0.4, and 0.5 log, respectively. With a 4-minute rub of ethanol 77% vol/vol on the (sebum-free) palm a reduction in aerobic flora of 2.3 log was reported but only 1.3 log on the forehead.⁵⁴ This problem was also originally reported by Christiansen,⁵⁵ who initially developed the German Society of Hygiene and Microbiology guidelines for testing skin antiseptics in sebum-rich and in other skin areas.

Table 44.2 provides a summary of different alcohols according to their efficacy as surgical hand scrubs/disinfectants at various concentrations and times of application. These results were obtained by comparable methods to the European norm, EN 12791.⁶⁶ They demonstrate that not only the alcohol species and its concentration but also the application time are determining factors for the efficacy of surgical scrubs, even if this could not be shown in all trials by some authors.⁶⁷ Furthermore, the data indicate that the immediate antibacterial effect of these alcohols is good enough to keep bacterial release under the glove low for at least 3 hours. This is explained by the slow regrowth of the skin flora, as observed with combination alcohol products such as with CHG.²⁴,²⁵ According to EN 12791, the immediate effect of a product for surgical hand disinfection used for 3 to 5 minutes must not be significantly less than that of the reference (ie, n-propanol 60% vol/vol within 3 minutes), a test for a 3-hour sustained effect is required only if there is an explicit claim about this effect (see chapter 42). In this case, the mean bacterial reduction caused by the product must be significantly stronger than that of the reference scrub after 3 hours on the gloved hand.

Alcohols are used either alone or in combination with one of the other chemicals listed previously, mainly to confer sustained activity, which they lack, but also to increase the antimicrobial effect. But overall impact of such combined products continues to be an area of debate (see chapters 19 and 42).²⁴,²⁵ As an example, when ethanol 77% vol/vol was used for skin antisepsis in combination with 1.5% iodine, a bacterial reduction of 2.3 log on a sebum-free and of 1.3 log on a sebum-rich environment was achieved in only 45 seconds,⁶⁸ whereas with ethanol alone, 4 minutes was needed. In combination with 0.5% CHG, the respective reductions were 2.2 and 0.9 log for the same period of application. For surgical scrubs, it has also been shown that the combination of 70% isopropanol with 0.5% CHG causes significant sustained (3 h) effects on the gloved hand regardless of the application time. A 5-minute application achieved, for example, an immediate 2.5 log reduction, but a sustained effect of 2.7 log,⁶⁰ and a 2-minute application caused corresponding effects of 0.7 and 1.4 log.⁶¹ With respect to the strong immediate and the resulting sustained effects of alcohols alone (if valid), it must be questioned whether a real sustained effect is needed for the surgical scrub if a product meets the requirement of EN 12791 regarding the immediate effect (see chapters 42 and 43).