Severe Soft Tissue Infections Research Articles

Severe Soft Tissue Infections of the Head and Neck: A Primer for Critical Care Physicians

Patients with severe infections of the potential spaces of the head and neck are commonly managed in the ICU. These infections may present with devastating complications such as airway obstruction, jugular septic thrombophlebitis, lung abscess, upper airway abscess rupture with asphyxiation, mediastinitis, pericarditis, and septic shock. A thorough understanding of the anatomy and microbiology of these infections is essential for proper management of these patients. Retropharyngeal, danger, prevertebral, lateral pharyngeal, and submandibular space infections and their site-specific clinical manifestations, complications, and therapeutic interventions are discussed.

Staphylococcus aureus Panton-Valentine Leukocidin Contributes to Inflammation and Muscle Tissue Injury

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) threatens public health worldwide, and epidemiologic data suggest that the Panton-Valentine Leukocidin (PVL) expressed by most CA-MRSA strains could contribute to severe human infections, particularly in young and immunocompetent hosts. PVL is proposed to induce cytolysis or apoptosis of phagocytes. However, recent comparisons of isogenic CA-MRSA strains with or without PVL have revealed no differences in human PMN cytolytic activity. Furthermore, many of the mouse studies performed to date have failed to demonstrate a virulence role for PVL, thereby provoking the question: does PVL have a mechanistic role in human infection? In this report, we evaluated the contribution of PVL to severe skin and soft tissue infection. We generated PVL mutants in CA-MRSA strains isolated from patients with necrotizing fasciitis and used these tools to evaluate the pathogenic role of PVL in vivo. In a model of necrotizing soft tissue infection, we found PVL caused significant damage of muscle but not the skin. Muscle injury was linked to induction of pro-inflammatory chemokines KC, MIP-2, and RANTES, and recruitment of neutrophils. Tissue damage was most prominent in young mice and in those strains of mice that more effectively cleared S. aureus, and was not significant in older mice and mouse strains that had a more limited immune response to the pathogen. PVL mediated injury could be blocked by pretreatment with anti-PVL antibodies. Our data provide new insights into CA-MRSA pathogenesis, epidemiology and therapeutics. PVL could contribute to the increased incidence of myositis in CA-MRSA infection, and the toxin could mediate tissue injury by mechanisms other than direct killing of phagocytes.

High fosfomycin concentrations in bone and peripheral soft tissue in diabetic patients presenting with bacterial foot infection

Appropriate antimicrobial therapy and surgical intervention may be required in diabetic patients presenting with severe bacterial foot infection. Methicillin-resistant Staphylococcus aureus (MRSA) agents such as fosfomycin are increasingly in demand because of recent concern regarding vancomycin and daptomycin efficacy and constant use. Intravenous fosfomycin is approved for the therapy of severe soft tissue infections and is highly active against methicillin-susceptible S. aureus and MRSA. in the present study we investigated fosfomycin's ability to penetrate bone tissue in diabetic patients suffering from severe bacterial foot infection. The well established microdialysis technique was utilized to determine fosfomycin concentrations in metatarsal bone in nine patients scheduled for partial bone resection due to bacterial foot infection and osteomyelitis. Plasma and unaffected subcutaneous adipose tissue served as reference compartments. After a single intravenous dose of approximately 100 mg of fosfomycin per kg of body weight, the mean C(max), T(max) and AUC(0-6) for bone were 96.4 mg/L, 3.9 h and 330.0 mg x h/L, respectively. The degree of tissue penetration as determined by the ratios of the AUC(0-6) for bone to plasma and for subcutaneous adipose tissue to plasma were 0.43 +/- 0.04 and 0.76 +/- 0.05, respectively. On the basis of relevant pharmacokinetic-pharmacodynamic indices, it seems that fosfomycin is an effective antibiotic for the treatment of deep-seated diabetic foot infections with osseous matrix involvement.

Application of the Laboratory Risk Indicator in Necrotising Fasciitis (LRINEC) Score to Patients in a Tropical Tertiary Referral Centre

The objective of this study was to assess the applicability and usefulness of the Laboratory Risk Indicator in Necrotising Fasciitis (LRINEC) score in patients from our institution. A retrospective analysis was undertaken of the case notes of all patients admitted to our facility between January 2002 and December 2005 with the admission diagnosis of necrotising fasciitis and the application of the LRINEC score upon the initial blood tests. The sensitivity, specificity and likelihood ratios were then calculated for patients with a LRINEC score of > or = 6 compared with the findings of a surgical biopsy. Twenty-eight patients were identified as having the admission diagnosis of necrotising fasciitis on the hospital database and were eligible for the study. Ten of these had biopsy-proven necrotising fasciitis. With a cut-off score of > or = 6, the LRINEC score had a sensitivity of 80%, specificity of 67%, a positive predictive value of 57% and a negative predictive value of 86% in distinguishing the patients with proven necrotising fasciitis from those with severe soft tissue infections. The likelihood ratio of a positive biopsy was 2.4 and the likelihood ratio of a negative biopsy was 0.3. A cut-off value of > or = 6 of the LRINEC score was not overly sensitive or specific, and the likelihood ratios suggest that, at this cut-off level, the LRINEC score would have only a very small effect on the post-test probability of the patients in the studied population having necrotising fasciitis.

Understanding the epidemic of community-associated MRSA and finding a cure: are we asking the right questions?

Understanding the epidemic of community-associated MRSA and finding a cure: are we asking the right questions?

Cryptococcal infection presenting as cellulitis in a renal transplant recipient

Opportunistic infections of skin and soft tissue represent a rare but serious complication following solid organ transplantation. We report a case of severe soft tissue infection caused by Cryptococcus neoformans in a renal transplant recipient. Physicians need to consider the possibility of opportunistic pathogens when managing infections in immunocompromised hosts, especially when symptoms persist despite seemingly appropriate empiric antimicrobial therapy. Tissue sampling for histological and microbiological evaluation is usually necessary to establish a diagnosis.

Necrotizing Fasciitis of the lower extremity: a case report and current concept of diagnosis and management

Necrotizing fasciitis is a severe soft tissue infection characterized by rapidly progressing necrosis, involving subcutaneous tissues. This rare condition carries high mortality rate and require prompt diagnosis and urgent treatment with radical debridement and antibiotics.We describe a case of 21-year old man who presented with the history of trivial injury to the knee. Initially he was admitted and treated for septic arthritis but later was diagnosed as necrotizing fasciitis which was successfully treated with no ill effects what so ever from this devastating condition.This rare condition has been reported in literature but still early diagnosis, which is a key for successful treatment, remains a challenge.

The Antioxidant Mimetic, MnTE-2-PyP, Reduces Intracellular Growth of Mycobacterium abscessus

Mycobacterium abscessus is a rapidly growing environmental mycobacterium that can cause severe skin, soft tissue, and lung infections. M. abscessus grows inside macrophages, and these cells release a vast number of proinflammatory cytokines in response to infections. The metalloporphyrin, MnTE-2-PyP, is a broad antioxidant that reduces inflammatory cell signaling. Macrophage-like THP-1 cells were infected with M. abscessus in the presence or absence of MnTE-2-PyP. MnTE-2-PyP significantly decreased, in a dose-dependent manner, the number of M. abscessus organisms recovered from infected THP-1 cells 4 and 8 days after infection. Furthermore, when combined with clarithromycin, MnTE-2-PyP additively reduced the number of cells associated with M. abscessus. A mechanism of bacterial growth inhibition by MnTE-2-PyP was then elucidated. It was found that MnTE-2-PyP promoted the survival of infected THP-1 cells and increased fusion of M. abscessus-containing phagosomes with lysosomes.

Severe soft tissue infections in dogs: 47 cases (1996–2006)

AbstractObjective– To describe the patient population, microbiological findings, treatment and outcome in dogs with severe soft tissue infections (SSTIs) and to compare survivors to nonsurvivors.Design– Retrospective study.Animals– Forty‐seven dogs with confirmed soft tissue infections originating from the SC tissues, muscle or fascia.Interventions– None.Measurements and Main Results– Physical and clinicopathologic data on presentation, microbiological and histopathological findings, antimicrobial treatment and outcome. Dogs with SSTIs were predominantly large breed dogs with a median body weight of 35.6 kg. Incidence of pre‐existing conditions (immunomodulating diseases, blunt trauma, injections, clean surgical procedures) that could have contributed to development of SSTIs was 34%. Abnormal physical examination and diagnostic parameters on presentation included increased body temperature (median temperature 39.5 °C [103.1 °F]) and low arterial blood pressure (median systolic blood pressure 103.5 mm Hg). While Streptococcus species were the most commonly isolated bacteria, the incidence of polymicrobial infections differed between antemortem (38.7%) and postmortem (57.1%) cultures. The overall survival rate was 46.8%. Survivors had a higher body weight and higher respiratory rate on presentation than nonsurvivors. Nonsurvivors had a significantly lower WBC count and higher lactate, BUN, aspartate aminotransferase, and bilirubin concentrations. Histopathologic examination of tissue specimens showed that the degree of necrosis was higher in survivors compared with nonsurvivors.Conclusions– SSTIs in dogs are serious conditions associated with high mortality, significant inflammatory changes, and cardiovascular compromise. A number of conditions, including those that compromise skin integrity and immunomodulating diseases have been identified in our patient population and could have contributed to development of SSTIs. Polymicrobial infections occurred in many cases, necessitating broad‐spectrum antimicrobial coverage.

Clinical Characteristics and Molecular Subtyping ofVibrio vulnificusIllnesses, Israel

Abstract During 1996–1997, a new Vibrio vulnificus biotype 3, which caused severe soft tissue infection after fishbone injury, emerged in Israel. We conducted a follow-up study from 1998 through 2005 to assess changing trends, outcomes, and molecular relatedness of the implicated strains. A total of 132 cases (71% confirmed and 29% suspected) of V. vulnificus biotype 3 infection were found. Most infections (95%) were related to percutaneous fish exposure, mainly tilapia (83%) or common carp (13%). Bacteremia, altered immune status, and history of ischemic heart disease were identified as independent risk factors for death, which reached a prevalence of 7.6%. Pulsed-field gel electrophoresis patterns of strains from 1998 through 2005 and from 1996 through 1997 showed a high degree of homogeneity and were distinct from those of V. vulnificus biotype 1. Infections caused by V. vulnificus biotype 3 continue affect the public’s health in Israel.

Epidemic of severe Streptococcus pyogenes infections in injecting drug users in the UK, 2003–2004

During the late 1990s, increases in referrals to the national reference laboratory of Streptococcus pyogenes isolates from injecting drug users (IDUs) with severe soft tissue infection indicated an emerging problem in the UK, later confirmed during the 2003-2004 European enhanced surveillance (Strep-EURO) programme. In light of these findings, further analyses were undertaken in an attempt to understand the reasons behind this increase in referrals. Single and multivariable analyses were undertaken to compare clinical, microbiological and demographic characteristics of IDUs diagnosed with severe S. pyogenes infection during the 2003-2004 enhanced surveillance study with those of other cases arising during this same period. Temporal and spatial analyses were undertaken for IDUs to identify clustering, as a means of understanding the transmission dynamics underpinning this increase. Infections in IDUs were spread across the UK, with some concentration in northern England and London. IDUs presented with a wide range of clinical manifestations, including pneumonia, which was found to be significantly more common in IDUs (OR 3.00) than in other cases. Marked differences in type distributions were found between IDUs and other cases, in particular the concentration of emm/M83 (22% of IDUs, 2% of non-IDUs). These findings indicate that an epidemic of severe S. pyogenes infections in IDUs occurred in the UK, peaking in 2003. The explanation for this rise remains unclear.

Coverage of Exposed Bones and Joints in Critically Ill Patients: Lower Extremity Salvage with Topical Negative Pressure Therapy

Soft tissue defects of the limb with exposure of tendons and bones in critically ill patients usually lead to extremity amputation. A potential treatment with topical negative pressure may allow split-thickness skin grafting to the bone, which leads to limb salvage. We report on 21 multimorbid patients, 46 to 80 years of age, with severe lower limb soft tissue loss and infection with exposed bone following débridement with critical limb ischemia. Attempts to salvage the extremities were undertaken with repeated surgical débridement followed by vacuum-assisted closure therapy and subsequent split-thickness skin grafting procedures. Infection control and limb salvage were achieved in all cases with multiple débridements, topical negative pressure therapy, and skin grafts. In all patients, the exposure of tendons and bones was reversible by this strategy without a free flap transfer. The patients described in this study were severely compromised by systemic and vascular disorders, so extremity amputation had been considered owing to the overall condition and the exposure of tendons and bones. Since it was possible to salvage the affected limbs with this straightforward and simple procedure, this type of treatment should be considered as a last attempt to prevent amputation.

Sinusitis And Orbital Cellulitis Due To Community-Associated Methicillin-Resistant Staphylococcus Aureus

Introduction Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) has a predilection to cause severe skin and soft tissue infection in both immunocompetent and immunocompromised adults. 1 Other serious invasive infections, such as necrotizing pneumonia, sepsis, bacteremia, sinusitis, and urinary tract infections, are on the rise. 2 We report a case of bacterial sinusitis and orbital cellulitis due to CA-MRSA.

Necrotizing fasciitis following transobturator tape treated by extensive surgery and hyperbaric oxygen

The transobturator sling procedure (TVT-O) was developed to minimize surgical risks involved in treating genuine stress incontinence. All data suggest that most risks associated with the retropubic route such as injuries to the bladder, intestines or vessels are practically obsolete with the obturator route. However, severe soft-tissue infections have been reported with this new technique. In this case report, necrotizing fasciitis (NF) developed shortly after a TVT-O procedure. This life-threatening complication required extensive debridements, a diverting colostomy, antibiotics, and eight sessions of hyperbaric oxygen (HBO) therapy. We emphasize the importance of a unified interdisciplinary clinical approach in severe NF with rapid progression and systemic toxemia. Primary, aggressive but tissue-saving debridements together with antibiotics are the cornerstones of therapy. HBO therapy can oxygenate infected hypoxic tissues to help marginally viable tissues survive, reduce the inflammatory response, improve leukocyte bacterial oxidative killing capacity, and achieve infection control and healing.

Cathelicidin LL-37 in Severe Streptococcus pyogenes Soft Tissue Infections in Humans

Severe soft tissue infections, such as necrotizing fasciitis and severe cellulitis, caused by group A streptococci (GAS) are rapidly progressing life-threatening infections characterized by massive bacterial loads in the tissue even late after the onset of infection. Antimicrobial peptides are important components of the innate host defense, and cathelicidins have been shown to protect against murine necrotic skin infections caused by GAS. However, it has been demonstrated that the streptococcal cysteine protease SpeB proteolytically inactivates the human cathelicidin LL-37 in vitro. Here we have investigated the expression of LL-37 and its interaction with GAS and SpeB during acute severe soft tissue infections by analyses of patient tissue biopsy specimens. The results showed large amounts of LL-37, both the proform (hCAP18) and the mature peptide, in the tissue. Confocal microscopy identified neutrophils as the main source of the peptide. A distinct colocalization between the bacteria and LL-37 could be noted, and bacterial loads showed positive correlation to the LL-37 levels. Areas with high LL-37 levels coincided with areas with large amounts of SpeB. Confocal microscopy confirmed strong colocalization of GAS, SpeB, and LL-37 at the bacterial surface. Taken together, the findings of this study provide in vivo support of the hypothesis that SpeB-mediated inactivation of LL-37 at the streptococcal surface represents a bacterial resistance mechanism at the infected tissue site in patients with severe GAS tissue infections.

Postprocedural Necrotizing Fasciitis: A 10-Year Retrospective Review

Necrotizing fasciitis (NF) is a severe soft tissue infection, which has a reported 25 per cent to 60 per cent mortality rate. In addition, NF has been reported to occur after invasive procedures. We present a 10-year retrospective study on postprocedural NF and its differences with community-acquired NF. A retrospective study was conducted from 1996 to 2006. Charts were searched using International Classification of Diseases, 9th Revision codes for NF and gas gangrene. Patients who developed NF in the area of their previous procedure without any other inciting cause of the NF were deemed eligible for the study. Eleven patients met eligibility criteria. Seven patients' initial procedures were elective, whereas four were semiemergent. The median age was 48 years (range, 24-81 years). The time between the initial procedure and operation for NF varied from 3 days to over 3 months. No single laboratory value helped in diagnosing NF. Sixteen different bacteria were isolated from the 11 patients. Ten of 11 patients required multiple debridements. There were four mortalities, three of whom had comorbidities known to predispose to infection. NF is a rare but serious complication after invasive procedures. As a result of important differences that exist between postprocedural and community-acquired NF, we propose that postprocedural NF should be classified in its own subcategory.

Multidrug-resistant methicillin-resistant Staphylococcus aureus (MRSA) strain in a men-who-have-sex-with-men (MSM) community in the United States: comment

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Methicillin-resistant Staphylococcus aureus (MRSA): focus on community-associated MRSA

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections are defined as occurring in patients who have no association with the healthcare setting. CA-MRSA has emerged as a common cause of community infections in the US and are distinct from MRSA strains classically associated with healthcare-associated infections from genotypic and phenotypic perspectives. They are frequently susceptible to non-beta-lactam antimicrobials, express the SCCmec type IV or V gene and contain the Panton-Valentine leukocidin virulence factor. They most commonly cause mild skin infections, but have been associated with severe soft tissue infection and with necrotising pneumonia.

Incidence and clinical characteristics of methicillin-resistant Staphylococcus aureus necrotizing fasciitis in a large urban hospital

Background Methicillin-resistant Staphylococcus aureus (MRSA) has become a prevalent health issue for soft-tissue infections. In severe soft-tissue infections such as necrotizing fasciitis, MRSA has been identified as an increasingly common pathogen. Herein, we report a 5-year experience of MRSA necrotizing fasciitis at a large urban hospital. Methods All cases of necrotizing fasciitis between 2001 and 2006 were reviewed. All patients were taken for surgical debridement. MRSA patients were identified and compared with the non-MRSA patients to identify any clinical variables that impacted incidence or severity of disease. A P value of less than .05 was considered significant. Results During the 5-year period, there were 74 cases of necrotizing fasciitis with a 39% prevalence of MRSA as the causative organism for the infection. The mean age of patients with MRSA fasciitis was 43 ± 3 years. There were no discernible social variables (eg, smoking, ethanol use, intravenous drug use) that predisposed patients to MRSA infection. The overall mortality rate was 15%, with no significant difference between groups. One hundred percent of MRSA specimens were susceptible to vancomycin or rifampin, 93% were susceptible to sulfamethoxazole/trimethoprim, and only 62% were susceptible to clindamycin. Conclusions The incidence of MRSA fasciitis may be much higher than initially suspected and prompt MRSA-directed antibiotic therapy should be administered. Clinicians should maintain a high index of suspicion for this organism in necrotizing fasciitis.

Necrotizing fasciitis in children: diagnostic and therapeutic aspects

Background Necrotizing fasciitis (NF) is a severe life-threatening soft tissue infection characterized by rapidly spreading necrosis of the fascia and the subcutaneous tissue. Its incidence owing to invasive Streptococcus pyogenes has significantly increased in children recently. Our experience with NF in children to describe diagnostic and therapeutic aspects is hence presented herein. Methods Records of children who were treated for NF in our unit from 1999 to 2006, inclusive, were reviewed retrospectively. Information recorded for each patient included medical history, clinical characteristics, diagnostic procedures, treatment methods, and the outcome. Results Thirteen patients with a mean age of 35 months were treated for NF during the study period. All of the 13 children had no previous immunosuppression. The predisposing factors were composed of varicella lesions, intramuscular injections, application of a cream containing menthol to the cervical region, penetrant gluteal trauma, omphalitis, dental abscess, and streptococcal toxic shock syndrome. The most common site of the initial involvement was the abdominal wall, followed by the gluteal region and thigh, head and neck, and upper and lower extremities. The initial skin presentations were induration or cellulitis and erythema and edema with progression to skin discoloration and bullae formation. Fever and tachycardia were the most common clinical features. S. pyogenes was the most common causative microorganism, followed by Staphylococcus epidermidis and Pseudomonas aeruginosa. All patients underwent extensive surgical debridement and received appropriate antibiotics and supportive therapy. Twelve patients survived, and 1 patient with delayed diagnosis of NF died of septic shock. Conclusion Although these infections are rare in children, their lethal potential and early diagnostic signs must be recognized. All children with NF should undergo early surgical debridement to prevent delay in treatment. The mortality and morbidity associated with NF in children can be decreased with clinical awareness, early diagnosis, and adequate and urgent surgical debridement followed by intensive supportive care and early wound resurfacing.