Skin and soft-tissue infections

NF-κB-Signaling-Targeted Immunomodulatory Nanoparticle with Photothermal and Quorum-Sensing Inhibition Effects for Efficient Healing of Biofilm-Infected Wounds

The development of therapeutics with high antimicrobial activity and immunomodulatory effects is urgently needed for the treatment of infected wounds due to the increasing danger posed by recalcitrant-infected wounds. In this study, we developed light-controlled antibacterial, photothermal, and immunomodulatory biomimetic N/hPDA@M nanoparticles (NPs). This nanoplatform was developed by loading flavonoid naringenin onto hollow mesoporous polydopamine NPs in a π-π-stacked configuration and encasing them with macrophage membranes. First, our N/hPDA@M NPs efficiently neutralized inflammatory factors present within the wound microenvironment by the integration of macrophage membranes. Afterward, the N/hPDA@M NPs effectively dismantled bacterial biofilms through a combination of the photothermal properties of PDA and the quorum sensing inhibitory effects of naringenin. It is worth noting that N/hPDA@M NPs near-infrared-enhanced release of naringenin exhibited specificity toward the NF-κB-signaling pathway, effectively mitigating the inflammatory response. This innovative design not only conferred remarkable antibacterial properties upon the N/hPDA@M NPs but also endowed them with the capacity to modulate inflammatory responses, curbing excessive inflammation and steering macrophage polarization toward the M2 phenotype. As a result, this multifaceted approach significantly contributes to expediting the healing process of infected skin wounds.

The role of anaerobic bacteria in cutaneous and soft tissue abscesses and infected cysts

This review presents the aerobic and anaerobic microbiological aspects and management of cutaneous and soft tissue abscesses, paronychia, anorectal, pilonidal, and perirectal abscesses, infected epidermal cysts, hidradenitis suppurativa, and pustular acne lesions. These infections often occur in different body sites or in areas that have been compromised or injured by foreign body, trauma, ischemia, malignancy or surgery. In addition to group A beta-hemolytic streptococci and Staphylococcus aureus, the indigenous aerobic and anaerobic cutaneous and mucous membranes local microflora usually is responsible for these generally polymicrobial infections. These infections may occasionally lead to serious potentially life-threatening local and systemic complications. The infections can progress rapidly and early recognition and proper medical and surgical management is the cornerstone of therapy.

Epidemiology and antibiotic susceptibility of bacteria causing skin and soft tissue infections in the USA and Europe: a guide to appropriate antimicrobial therapy

Susceptibility data for all organisms associated with a range of skin and soft tissue infections (SSTI) in hospitalised patients were studied. Data were reported by clinical laboratories in the USA, France, Germany, Italy and Spain during 2001 which participate in The Surveillance Network (TSN). Staphylococcus aureus, Enterococcus spp. and coagulase-negative staphylococci (CNS), Escherichia coli and Pseudomonas aeruginosa were the most prevalent pathogens in all countries. MRSA was detected in 44.4, 34.7, 12.4, 41.8 and 32. 4% of S. aureus in each country, respectively. The majority of MRSA were cross resistant to other compound classes tested except for vancomycin (100% susceptible) trimethoprim-sulphamethoxazole with range 1.7% (France) to 15.9% (Italy) resistant, and gentamicin with range 12.2% (France) to 87.0% (Italy) resistant. More than 99.0% of MSSA tested susceptible to ceftriaxone and >94.9% to trimethoprim-sulphamethoxazole. 87.2% (France) to 94.6% of MSSA (Germany) were ciprofloxacin susceptible; 73.2% (USA) to 86.6% (Spain) were erythromycin susceptible; 85.4% (Italy) to 99.2% (France) were gentamicin susceptible. MSSA were more frequently found and generally more antibiotic susceptible from out patients. Overall, 100% of Streptococcus agalactiae and Streptococcus pyogenes were susceptible to penicillin, ceftriaxone and cefotaxime. Macrolide resistance was common among S. agalactiae (20.7%, Germany to 10%, Italy and Spain), S. pyogenes (19.2%, France to 11.1%, USA) and viridans streptococci (25.7%, France to 14.1%, Germany). Vancomycin-resistant Enterococcus spp. were uncommon outside the USA (17.5%) and Italy (7.4%). For all countries susceptibility of E. coli was 100% to imipenem, >98.7% to amikacin, >96.0% to ceftriaxone and cefotaxime. Susceptibility of E. coli isolates to ciprofloxacin was 77.6% in Spain to 94.3% in Germany. Klebsiella spp., Proteus spp., Citrobacter spp. and Enterobacter spp. displayed varying susceptibilities between countries to drugs tested. Putative extended spectrum beta-lactamase expression in E. coli remained rare comprising 4-5% of isolates in USA, Italy and Spain and in France and Germany <2%. For P. aeruginosa piperacillin-tazobactam, amikacin, imipenem and ceftazidime were the most active compounds tested irrespective of region. Surveillance data should be considered when selecting empirical therapy for treating SSTI.

Soft tissue infections of the extremities in an orthopaedic centre in the UK

OBJECTIVES

To determine the spectrum, and clinical impact of acute extremity soft tissue infections, encountered in the Orthopaedic service of an inner city hospital in UK.

METHODS

Patients requiring admission for an acute limb soft tissue infection to the Orthopaedic unit of the Manchester Royal Infirmary, UK, between July 1996 and 2001 were identified from our database. Infections involving the groin and axilla, those developing within 30 days of a surgical procedure, and patients with chronic soft tissue ulcers or infections were not considered.

RESULTS

Of 142 infections the majority were cellulitis (50%) and superficial abscesses (34.5%). Most were secondary to trauma (31.6%), human or animal bites (20%) and intravenous drug abuse (17.6%). Although most patients were young and otherwise healthy, ten developed significant complications: myonecrosis requiring below knee amputation (1), acute carpal tunnel syndrome (1), osteomyelitis (6), extensive skin loss requiring reconstruction (1), deep vein thrombosis (1). Seven hundred and eighty four hospital inpatient days and 143 operative interventions were devoted to these patients. The estimated cost for each episode of soft tissue infection was pound 1011. In 25% of cases earlier referral to a surgical service would have been more appropriate.

CONCLUSIONS

Soft tissue infections of the extremities confer significant morbidity and impose an important burden on medical resources.

Clinical, microbial, and biochemical aspects of the exfoliative toxins causing staphylococcal scalded-skin syndrome

The exfoliative (epidermolytic) toxins of Staphylococcus aureus are the causative agents of the staphylococcal scalded-skin syndrome (SSSS), a blistering skin disorder that predominantly affects children. Clinical features of SSSS vary along a spectrum, ranging from a few localized blisters to generalized exfoliation covering almost the entire body. The toxins act specifically at the zona granulosa of the epidermis to produce the characteristic exfoliation, although the mechanism by which this is achieved is still poorly understood. Despite the availability of antibiotics, SSSS carries a significant mortality rate, particularly among neonates with secondary complications of epidermal loss and among adults with underlying diseases. The aim of this article is to provide a comprehensive review of the literature spanning more than a century and to cover all aspects of the disease. The epidemiology, clinical features, potential complications, risk factors, susceptibility, diagnosis, differential diagnoses, investigations currently available, treatment options, and preventive measures are all discussed in detail. Recent crystallographic data on the toxins has provided us with a clearer and more defined approach to studying the disease. Understanding their mode of action has important implications in future treatment and prevention of SSSS and other diseases, and knowledge of their specific site of action may provide a useful tool for physiologists, dermatologists, and pharmacologists.

Comparative tolerability of erythromycin and newer macrolide antibacterials in paediatric patients

The macrolides are a well established group of antibacterials frequently used in general practice. The most frequently used macrolides in paediatric patients are erythromycin, a naturally occurring compound, and clarithromycin and azithromycin, recently developed macrolides. Overall adverse effect rates of 7 to 26% for erythromycin, 14 to 26% for clarithromycin, and 6 to 27% for azithromycin have been described in children. Adverse gastrointestinal effects, including nausea, vomiting, diarrhoea and abdominal cramps, are the most common problems in children. Allergic reactions, hepatotoxicity, ototoxicity and adverse effects involving the central and peripheral nervous systems have also been observed in children. Stevens-Johnson, Schonlein-Henoch and Churg-Strauss syndromes have been rarely described in children. Treatment-related laboratory abnormalities have been recorded in 2 to 4% of erythromycin- and in 0 to 1% of both clarithromycin- and azithromycin-treated children. Elevation in liver function tests was the most common abnormality cited. Increased macrolide use in children in recent years has resulted in a growing potential for drug interactions between them and other pharmacologically active agents via the inhibition of cytochrome P450 (CYP) microsomal enzymes. Drug interactions with theophylline, cyclosporin, carbamazepine, terfenadine and warfarin limit erythromycin use. Clarithromycin is a weak inducer of CYP and exhibits fewer drug-drug interactions than erythromycin. However, its use with theophylline, carbamazepine and terfenadine is contraindicated. In contrast, no significant interactions have been reported with azithromycin to date. Macrolides have been proven to be well tolerated in the treatment of upper and lower respiratory tract infections, skin and soft tissue infections, and also in less frequent infections occurring in paediatric patients. In addition, clarithromycin and azithromycin have shown good tolerability profiles in immunocompromised paediatric patients. In conclusion, macrolides antibacterials have proven to be well tolerated in paediatric patients. Although the incidence of adverse effects is similar with the use of erythromycin and the newer macrolides, drug interactions occur significantly less when clarithromycin or azithromycin are administered.

Outpatient parenteral anti-infective therapy for skin and soft-tissue infections

Skin and soft tissue infections (SSIs) are one of the many infectious diseases that can be treated by outpatient parenteral anti-infective therapy (OPAT). Determining whether a patient with SSIs is treated topically, orally, or parenterally depends on the severity of infection and host factors. The decision to hospitalize, initiate, or transition to OPAT with SSIs depends on the medical assessment and consideration of available resources for OPAT. Anti-infective selection depends on the clinical presentation, likely organisms, pharmacodynamics, pharmacokinetics, and drug stability.

Streptococcal toxic shock syndrome presenting as suspected child abuse

Natural disease processes can predispose individuals to develop external body lesions that mimic traumatic injury. This can be particularly problematic in pediatric cases in which clinicians are alerted to the problems of child abuse. Streptococcal toxic shock syndrome is a systemic infectious illness that can manifest itself with erythematous and necrotizing skin lesions. We report a fatal case of streptococcal toxic shock syndrome in a 4-year-old girl who presented with skin lesions that were initially thought to be traumatic in origin. A report of possible child abuse was filed with the state. Based on the morphologic findings and bacteriologic culture results at autopsy, these lesions and the cause of death in this case were instead determined to result from streptococcal toxic shock syndrome.

Addition of rifampin to cephalexin therapy for recalcitrant staphylococcal skin infections--an observation

We report two pediatric patients with recalcitrant staphylococcal infections whose infections resolved when rifampin was added to standard antistaphylococcal therapy. One patient had a post-varicella staphylococcal ulcerative lesion and did not respond to cephalexin alone but did respond when rifampin was added. A second patient had staphylococcal bullous impetigo and did not respond to dicloxacillin or cephalexin but did respond when rifampin was added to the cephalexin. If a patient fails to respond to traditional antistaphylococcal therapy, the addition of rifampin may be beneficial.

Occult Streptococcus pyogenes in cellulitis: demonstration by immunofluorescence

A 23-year-old man developed cellulitis and ascending lymphangitis of the right leg. Blood cultures and skin saline aspirates were sterile. Gram stain of the aspirate did not show any bacteria. Direct and indirect immunofluorescent staining with polyclonal and monoclonal antibodies to Streptococcus pyogenes revealed streptococci in the reticular dermis. The cellulitis resolved following treatment with intravenous cefazoline.

Aeromonas hydrophila: myofascial necrosis and sepsis

An alcoholic patient with ascites was admitted to the intensive care unit for gastrointestinal bleeding. He subsequently developed spontaneous myonecrosis of the extremities culminating in sepsis syndrome. This was a unique, non-traumatic presentation of Aeromonas hydrophila soft tissue injury.

Irrigation-aspiration for culturing draining decubitus ulcers: correlation of bacteriological findings with a clinical inflammatory scoring index

Biopsy of infected decubitus ulcers for culture disrupts tissues and may disseminate infection. Antimicrobial prophylaxis to prevent dissemination of infection may adversely affect biopsy culture results. Irrigation-aspiration to obtain submarginal specimens from draining decubitus ulcers was studied as an atraumatic, noninvasive culturing technique to serve as an alternative to biopsy in research activities. Two aspirates were obtained serially from 32 subjects; in 12 subjects, biopsies were also performed immediately. A median of 4.5 bacterial species was recovered per ulcer by irrigation-aspiration. Recent antimicrobial treatment had no evident effect on the recovery of bacterial species in general or, specifically, on the recovery of Bacteroides species. Concordance of results for both aspirates was 97.6% for aerobes and 91.8% for anaerobes, indicating no interactive methodological effect of the first irrigation-aspiration on the second. Compared with biopsy isolates for one aspirate, the sensitivity was 93% and the specificity was 99.0%; for another aspirate, the sensitivity was 94.7% and the specificity was 99.5%. The positive predictive value for either aspirate was greater than or equal to 93.9%. A weighted clinical index to score inflammatory ulcer characteristics was devised (score range, 0 to 15). In the absence of anaerobes in 15 subjects, the mean score was 6.1 +/- 3.5; in the presence of anaerobes in 17 subjects, the mean score was 9.4 +/- 3.2 (P = 0.008). The presence of aerobic gram-positive or gram-negative species did not significantly affect scores. Irrigation-aspiration for culture and clinical scoring of inflammation should permit independent serial measures of bacteriological and clinical courses of draining decubitus ulcers without patient risk or discomfort.

Skin tissue fluid levels of cefotiam in healthy man following oral cefotiam hexetil

Cefotiam hexetil is a pro-drug of cefotiam available for oral administration. To evaluate cefotiam concentrations at the active site in skin and soft-tissue infections, drug levels in skin suction blister fluid (SBF), cantharides blister fluid (CBF) and serum were determined. Six healthy subjects received oral cefotiam 400 mg as cefotiam hexetil. On an other day 200 mg was injected intravenously. Following the oral dose, the bioavailability of cefotiam was 45.5%, and the maximum concentration in serum of 2.6 mg.l-1 was obtained at 2.1 h. Peak concentrations in both types of blister fluid (0.9 mg.l-1) were significantly lower than after the iv dose (SBF 1.4 mg.l-1, CBF 1.5 mg.l-1), and the peak levels occurred later (3.3 versus 1.5 h in CBF). Despite the delay, the extent of penetration was about 100% following either mode of administration (SBF, iv dose 112%, oral dose 117%). The cefotiam level in skin blister fluids declined significantly more slowly than the serum level. Following the oral dose, the mean terminal half life was serum 0.8 h, SBF 2.6 h and CBF 4.6 h. Cefotiam concentrations in the blister fluids were close to the MIC90 of Staphylococcus aureus, S. epidermis and H. influenzae and exceeded the MIC90 of Streptococci, E. coli and Proteus mirabilis. Thus, the oral administration of cefotiam 400 mg t.i.d. should be curative in the majority of bacterial infections of the skin and soft-tissues.

Toxic shock syndrome in scalded children

Five patients showing clinical signs resembling the 'toxic shock syndrome' presented over a 4-month period at the Wessex Regional Burns Centre. Toxin-producing isolates of Staphylococcus aureus were made from wound swabs in four of the five patients. Four different phage types producing four different toxins were observed. Seven other patients yielded staphylococci from wound swabs but did not develop the toxic shock syndrome. In three of these latter patients the staphylococcus isolated was toxin producing. Since the syndrome carries a significant mortality risk it is desirable that it is recognized and treated without delay. To this end a simplified set of criteria for the identification of probable toxic shock syndrome cases is proposed. The observations suggest that toxic shock syndrome is more common than previously supposed. The syndrome may show a broad spectrum in its clinical presentation, and involve a wide range of staphylococcal phage types with possible involvement of several different enterotoxins.

The diabetic foot

Diabetic foot lesions most commonly result from a combination of neuropathy and vascular disease in the lower extremity, and may be the presenting feature of diabetes in the older patient. Insufficient attention previously has been given to the careful clinical assessment of the foot, which enables the physician to recognize those patients who are at particular risk of ulceration. The high-risk patient requires education and frequent follow up to reduce the risk of lesions developing. If ulceration develops, healing is likely to occur if the vascular supply is adequate, infection and the blood glucose are controlled, and pressures that may have caused the ulcer are relieved. The ischemic foot requires full vascular assessment, involving colleagues from vascular surgery. The key to a future reduction in the incidence of diabetic foot ulceration is the setting up of a foot care team in which the skills of nurses, podiatrists, orthotists, physicians, and surgeons are combined. The most important members of the team, however, are the patients, who must be convinced that regular foot care will reduce their chances of developing ulceration and other catastrophic consequences, such as amputation.