Imaging of Soft Tissue Infections

Soft tissue and osseous musculoskeletal infections are common but can be difficult to diagnose clinically. Signs, symptoms, and physical examination findings may be nonspecific, and laboratory values can be inconclusive. The extent of disease may also be underestimated on physical examination. Soft tissue infections most commonly occur secondary to direct inoculation from broken skin and less frequently due to the seeding of the soft tissues from hematogenous spread, while osseous infections are more commonly due to hematogenous seeding. Infections may also be iatrogenic, following surgery or other procedural interventions. High-resolution ultrasound is an extremely useful imaging modality in the evaluation of musculoskeletal soft tissue and joint infections, and can occasionally be used to evaluate osseous infections as well. Ultrasound can aid in the early diagnosis of musculoskeletal infections, allowing for prompt treatment, decreased risk of complications, and treatment optimization. Ultrasound is sensitive and specific in evaluating soft tissue edema and hyperemia; soft tissue abscesses; joint, bursal and tendon sheath effusions/synovitis; and subperiosteal abscesses. This article describes the typical high-resolution grayscale as well as color and power Doppler ultrasound imaging findings of soft tissue infections including cellulitis, fasciitis, necrotizing deep soft tissue infection, pyomyositis, soft tissue abscess, infectious bursitis, and infectious tenosynovitis. Ultrasound findings of septic arthritis as well as osteomyelitis, such as subperiosteal spread of infection (subperiosteal abscess). are also reviewed. In addition, the use of ultrasound to guide fluid and tissue sampling is discussed.

The authors reviewed patients who developed sepsis or soft tissue infections caused by marine Vibrio bacteria in Florida. Marine Vibrio bacteria are the most common bacteria found in seawater. They are concentrated in marine animals that feed by filtration such as oysters and clams. These bacteria can cause gastroenteritis, sepsis, cellulitis leading to necrotizing soft tissue infection after exposure to seawater or consumption of raw seafood. The authors received 182 systemic infections that occurred in Florida between January 1, 1979, and December 31, 1991, which were treated by the authors or were reported to the Florida Department of Health and Rehabilitative Services. Patients were divided into two groups depending on whether they presented with primary bacteremia or soft tissue infection. Seventy-one patients had been exposed to these bacteria by eating raw seafood, 94 had direct exposure to seawater, and exposure was uncertain in 27 patients. Vibrio species were cultured from the blood of 103 patients and from wounds or soft tissues of 113. An additional 5 patients had cellulitis but bacteria were not cultured from these sites. In patients in whom it could be determined, 93 had primary soft tissue infections and 82 had primary bacteremia. Twenty-four patients had necrotizing soft tissue infections and required surgical debridement. Three of these 24 patients required amputation. Thirty-seven (20.3%) patients died. Severe liver disease occurred in 54 patients and 25 of these patients died. Marine Vibrio bacteria can cause sepsis and soft tissue infections, especially in individuals with severe liver disease and other chronic illnesses such as diabetes mellitus. The authors believe all individuals, especially those with systemic illness, should be warned against eating raw seafood.

Objective: In this prospective study we analyzed clinical spectrum of infections and there outcome in patients with diabetes mellitus and compared it with nondiabeticcontrols admitted in Endocrinology division of a tertiary care hospital.Methods: This was a prospective, longitudinal study of 242 diabetic and non-diabetic subjects. Patients were studied in terms of clinical picture, biochemical, hematological and microbiological profile, type and severity of infection, treatment received, and final outcome. There were 142 diabetic patients in group 1 and 100 nondiabetic patients in group 2 served as control. Study subjects were followed for a median period of one year (52 weeks in diabetics, 65 weeks in non-diabetics) after discharge from the ward.Results: Diabetic patients admitted because of infections were older than their non-diabetic counterparts (74% vs 51%> 50 years; p<0.001) and mounted a less inflammatory response in terms of fever and leucocytosis(55% vs 82%:P<0.001).Urinary tract infections were the commonest infections observed among in-hospital diabetic as well as non-diabetic patients (36% vs. 30%; P>0.3). Diabetics contract some specific infections exclusively, like emphysematous pyelonephritis and foot infections, while respiratory infections were more commonly seen in nondiabetic patients (31% vs. 11%; P<0.001).Staphylococcus aureus was the commonest organism involved in soft tissue and diabetic foot infections (32% vs. 19%; P<0.03). Though mean hospital stay was equal in either group it was significantly longer in diabetic subjects when statistically adjusted for APACHE score.Comparative mortality rates were higher in non-diabetics with in-hospital deaths, followup deaths and total deaths of11%, 6.1% and 17.2% vs 4.9%, 4% and 9.1% respectively but re-infections on follow-up occurred more in diabetics (15% vs.2.6%; P=0.005).Conclusion: Poor glycaemic control and less inflammatory response in terms of fever and leucocytosis, longer hospital stay with increased chances of reinfections are poor prognostic indicators for outcomes in diabetic patients admitted with infections. Urinary tract infections and soft tissue infections particularly foot infectionsare causes of concern in our diabetic patients. JMS 2018: 21 (2):84-90

Twenty-seven pedal soft tissue and bone infections in 26 patients were treated with surgical necrectomy of infected tissues and implantation of antibiotic-loaded polymethyl methacrylate bone cement beads on chains. The definitive diagnosis of the infected tissues was obtained by culture and histologic examination in all of the cases. A wide variety of foot infections was successfully treated in this manner. The success rate without recurrence of osteomyelitis or soft tissue infection was 95% in this study at an average of 16 months after surgery.

To provide an update on the diagnosis and management of skin, soft-tissue, and osteoarticular infections in children. Our understanding of the epidemiology of skin and soft-tissue infections and osteoarticular infections is changing rapidly. Community-associated methicillin-resistant Staphylococcus aureus has become a predominant cause of childhood skin and soft-tissue infections. Kingella kingae is also increasingly identified as a cause of osteoarticular infections. Challenges in Staphylococcus aureus treatment and Kingella kingae identification are changing the approach to skin and soft-tissue infections and osteoarticular infections. Community-associated methicillin-resistant Staphylococcus aureus should be considered a cause of skin and soft-tissue infections. Empiric antimicrobial choices should be modified in areas in which there is a more than 10% prevalence of community-associated methicillin-resistant Staphylococcus aureus infection. Decontamination of shared sports equipment should be undertaken to minimize person-to-person spread. No established guideline for eradication of carriage of community-associated methicillin-resistant Staphylococcus aureus exists. Kingella kingae is a more prevalent cause of osteoarticular infections than previously recognized and can cause outbreaks of invasive infection via person-to-person transmission. Modification of culturing procedures for osteoarticular infections including inoculation of infected joint fluid and bone in blood-culture bottles should be considered.

Community-associated methicillin-resistant Staphylococcus aureus (MRSA) is a growing problem in the pediatric population, causing many soft tissue infections. This study was designed to examine fingernail carriage of MRSA in children and their caregivers as a possible link to community-associated MRSA soft tissue infections in children. We documented the prevalence of MRSA under the fingernails of children and the caregivers of pediatric patients with soft tissue infections and compared the prevalence with MRSA under the fingernails of children and the caregivers of children with no history of soft tissue infections. Children with soft tissue infections and their caregivers (50 subjects) had three fingernails of each hand swabbed and plated and these were compared with a control group of children and their caregivers (150 subjects) who had no history of MRSA or soft tissue infection. Caregivers and children in the study group were more likely than caregivers and the children in the control group to have MRSA under their fingernails (P < 0.05). Soft tissue infections in the study group were found most commonly in the diapering area (66%). MRSA carriage was evident under the fingernails of children and caregivers. Caregivers and their children who have soft tissue infections are more likely to have MRSA growth under fingernails than caregivers or their children who have no history of MRSA or soft tissue infections. Our study suggests that caregivers could be contributing to soft tissue infections in their children.

Clostridium ramosum is one of the anaerobes commonly implicated in soft tissue and intra-abdominal infections. Invasive systemic infections and bacteremias are rare, however, because C. ramosum is less virulent compared with C. perfringens and other clostridia [1]. We report a case of osteomyelitis and bacteremia caused by C. ramosum in a patient with multiple pressure sores. Case Report. A 91-year-old nursing home resident, with hypertension and diabetes, was referred for evaluation of fever. Initial assessment revealed a demented, bedridden patient who appeared toxic, with a temperature of 102°F. She had multiple pressure sores, including stage IV ulcers over the left hip (9 × 7 cm) and sacrum (9.5 × 8 cm) and a stage III ulcer over the right hip (4 × 3.5 cm). The ulcer over the hip extended to the bone and had a foul-smelling purulent discharge and necrotic debris at the base. Further examination was unremarkable except for scattered rales and a short aortic ejection systolic murmur. Laboratory results showed leukocytosis (18.9) with a left shift and anemia (hematocrit 22.7). Urinalysis was normal, and a chest roentgenogram did not reveal any infiltrates. Blood cultures were drawn, and the patient began receiving ampicillin-sulbactam and gentamicin. The two sets of blood cultures performed at different time intervals, from different sites, both yieldedC. ramosum.Blood cultures were incubated in the BACTEC 9240 system (Becton Dickinson, Sparks, MD) and subcultured on a blood agar plate and CDC’s blood agar plate media with a gas pack pouch anaerobic system (BBL Becton Dickinson Microbiology systems, Cockeysville, MD). The identity of the organism was established with the API 20 A anaerobic strip (bioMerieux, Hazelwood, MO). A computed tomographic scan of the abdomen and pelvis, although negative for abdominal pathology, revealed a large ulcer over the left hip, intramedullary gas in the femoral head, and a small pocket of fluid anterior to the hip consistent with osteomyelitis. Gas was also seen in the soft tissue surrounding the ulcer. Antibiotics were continued and surgical debridement was done. The patient received a packed red blood cell transfusion for anemia, and blood sugars were controlled with multiple daily doses of regular insulin. A transthoracic echocardiogram showed mild aortic stenosis but did not reveal any evidence of vegetations. The patient responded well to treatment and was afebrile by the third day. Subsequent blood cultures were negative forC. ramosum.Two weeks later, the patient remained afebrile, the pressure sores appeared to be healing, and she was discharged to the nursing home on antibiotics. Discussion. C. ramosum is an anaerobic, spore-forming, non-motile, thin, gram-positive rod, which occurs singly, in pairs, or in short chains. It was first isolated by Veillon and Zuber in 1898 [2]. Holdeman et al. [3] found that it was a spore-forming anaerobe and placed it in the genus Clostridia. It is indigenous to the human intestinal tract and has been isolated from human feces [1]. C. ramosum has frequently been implicated in wound infections after intraabdominal trauma, acute bowel perforation, and colorectal abscesses [4,5]. However, it has seldom been isolated from pressure sores [6]. Infected pressure sores can cause metastatic or contiguous osteomyelitis. Anaerobic osteomyelitis is increasingly recognized in this setting, but clostridia have not often been implicated [7]. In our patient, bacteremia probably resulted from the severely infected pressure sores. Evidence of infection with a gas-forming organism in soft tissues around the hip and isolation of C. ramosum from two separate sets of blood cultures lend credence to our assumption. The incidence of clinically significant clostridial bacteremias has been increasing, and isolated cases of unusual clostridial bacteremias have been reported in patients with pressure sores [8]. C. ramosum bacteremia has been reported in a patient with acute bowel perforation and in a renal allograft recipient with mural endocarditis [5,9]. Our report demonstrates C. ramosum as a pathogen causing soft tissue infection, osteomyelitis, and bacteremia in the setting of pressure sores. C. ramosum is often resistant to penicillin and shows varying susceptibility to clindamycin and cephalosporins. This can potentially result in therapeutic failure [10]. Infected pressure sores should be recognized as a source of deep-seated clostridial infections, including bacteremia and osteomyelitis. We also emphasize the importance of species identification, if not antibiotic susceptibility testing, in clostridial infections.

Type 2 diabetes mellitus is a chronic pathology characterized by high prevalence, high morbidity and mortality. According to the data of the Ministry of Health of Volgograd region the number of patients with type 2 diabetes was 68,227 people on 01.01.2014. Medical and social significance of type 2 diabetes mellitus is determined by its complications. Skin and soft tissue infections (SSTIs) in patients with type 2 diabetes are among the main factors of hospitalization and mortality [1]. Diabetic foot syndrome is found in 30-80% of patients [2]. Pharmacoepidemiological analysis of the structure of skin and soft tissues infections in patients with type 2 diabetes, taking into account data on pathogens, parameters of their sensitivity, analysis of prescribed medicines and evaluation of their compliance with current clinical guidelines and standards. A retrospective descriptive cross-sectional pharmacoepidemiological study using randomization by random numbers. The sample consisted of 253 medical records of patients with SSTIs and type 2 diabetes. These were patients admitted to the surgical departments of hospitals of the city of Volgograd for the period from January 2011 to December 2014. Gender structure was the following: 51.4% - women, 48.6% - men. The average age of patients was 64.5 years. The average number of hospital days was 19,5 ± 14,9. Diabetic foot syndrome was found in 81.3% of cases (n-204). The most common forms of diabetic foot syndrome were the following: gangrene of the lower extremities - 28% (n-58), ulcers of the skin - 26% (n-53), mixed forms of SSTIs - 18% (n-37 ). Surgical manipulations were performed in 39.1% of cases (n-99), including amputations in 65.7% (n-65) of cases. The blood glucose level on admission was studied in 97.6% (n-247), at discharge - in 89% (n-225). Urine analysis on admission was performed in 66.4% of patients (n-168), at discharge - in 51% of patients (n-129). The glycemic profile was studied in 81.4% of patients (n-206). Bacteriological sowing was carried out in 19% (n-48) of cases: blood - 4,2% (n-2), urine - 6,2% (n-3) (the growth of microorganisms was not detected in 100%); bacteriological sowing from the wound - in 89.6% (n-43), the growth of microorganisms were identified in 95.7% (n-44). Most common pathogens were: St. aureus - 28%, E. coli - 19%, St. epidermidis - 14%. Antibacterial medications were prescribed in 86% (n-216). These were: cephalosporin of the III generation - ceftriaxone (49.4%), other synthetic antibacterials - metronidazole (21%), fluoroquinolone - ciprofloxacin (7.5%). The highest levels of bacterial resistance of SSTIs pathogens were found to beta-lactam antibiotics (amoxicillin/clavulanic acid, ceftriaxone, and ampicillin), rifampin, and gentamicin. The highest levels of sensitivity of SSTIs pathogens were observed to levofloxacin, to vancomycin and meropenem. There is a vicious circle in patients with type 2 diabetes: the infectious process leads to decompensation of carbohydrate metabolism parameters; in turn, hyperglycemia leads to increase of severity of SSTIs. Normalization of glucose levels promotes prompt relief of symptoms of infection and bacterial eradication, rational treatment of infection contributes to rapid correction of glucose level. Therefore, an essential element of comprehensive treatment of this group of patients should be rational antibiotic therapy; the choice of medication should be based on the severity of the disease and potential etiologic agents [3]. The analysis of the degree of conformity of the pharmacotherapy to existing standards is a way to optimize the treatment of the given group of patients [4].

Diabetes mellitus is a disease that affects millions around the globe. It also comes with a major complication, diabetic foot ulcers. Lower extremities having little to no vascularity in diabetic people leads to wounds that are unable to heal on their own. These wounds later become infected and cause osteomyelitis, a condition in which the infection in soft tissues of the lower extremities spread to the bones of the foot.Charcot arthropathy is one of the more serious foot issues that can arise from diabetic neuropathy. The soft tissues, joints, and bones of the foot or ankle are all impacted by Charcot. The joints in the foot or ankle might dislocate when the bones deteriorate and become brittle. Diabetes patients who have their soft tissues and bones infected might even have to get their extremities amputated if not managed right on time. We describe the case of a 66-year-old man with type 1 diabetes mellitus who presented to the emergency department with increasing pain in the right foot. There was a hyperemic discharge coming out of his wound which increased gradually over time. The patient’s been using Lantus and Novorapid and his blood glucose measurement at the time of admission was 466. Our patient said that he was hospitalized in the intensive care unit due to diabetic ketoacidosis 20 days before he applied to our emergency department, and his wounds, discharge, pain, and redness increased after this incident. We requested his anteroposterior and lateral radiographs of the right foot and a lower extremity CT. The scans were examined carefully and at last, amputation was recommended for the patient. The patient did decline our offer and wanted to go home with a dressing. Ampicillin/sulbactam and ciprofloxacin were started. We also recommended him see infectious diseases and plastic surgery consultants in the following daysI hope you may be interested in the results of our study in this direction.

Staphylococcus aureus is a major pathogen causing bacteraemia, pneumonia, skin and soft tissue infections (SSTIs), and osteomyelitis. Over the past 50 years, it has acquired resistance to antimicrobials including the penicillinase-resistant ones like methicillin. Rapid identification and susceptibility testing are mandatory to prevent further dissemination of MRSA and to provide effective antimicrobial treatment. Hence, methods used to detect MRSA should be rapid with high sensitivity and specificity.1) To compare various phenotypic methods for MRSA detection. 2) To confirm the phenotypic results with Polymerase Chain Reaction. 3) To evaluate the susceptibility of MRSA isolates to other antimicrobial agents.Eighty four MRSA isolates from soft tissue and bone samples identified by the cefoxitin (30µg) disc diffusion method were subjected to Oxacillin Screen Agar (OSA), cefoxitin E-strip, automated identification &amp; sensitivity testing using BD Phoenix system and Polymerase Chain Reaction using the GeneXpert for mecA gene detection.Although all 84 isolates were resistant by cefoxitin disk diffusion, 83 (95.4%) isolates were positive for the mecA gene. The sensitivities of the OSA, cefoxitin E-strip and BD Phoenix system were 79.5%, 80.7%, and 100%, respectively. All the isolates were sensitive to vancomycin and linezolid. 70% of the isolates were sensitive to cotrimoxazole whereas maximum resistance of 76% was seen to ciprofloxacin.Automated identification by BD Phoenix system, if available, can be considered as the most sensitive phenotypic method for MRSA detection, while cefoxitin E-strip is the most appropriate test in a resource poor setting.

Necrotizing fasciitis caused by diabetic foot

Objective To summarize X-ray and CT findings of soft tissue and bone infections secondary to acquired immunodeficiency syndrome (AIDS).Methods The data of X-ray and CT findings of soft tissue and bone infections in 18 patients with AIDS were retrospectively collected and analyzed.Results Of 18 patients with AIDS,the CT features of soft tissue demonstrated that subcutaneous patchy high density in 1 case which considered as cellulitis,round low density lesions with ring enhancement in 6 cases which considered as soft tissue abscesses,heterogeneous density lesions with peripheral enhancement in 1 case which considered as pyomyositis.Of 18 patients with AIDS,septic arthritis was found in 4 cases involving knee lesion in 3 cases and hip lesion.In the 4 case,the X-ray films showed bony destruction in 2 cases and the CT showed bone destruction in 3 cases and arthroedema in 4 cases.Of 18 patients with AIDS,osteomyelitis was found in 9 cases of which tuberculosis was considered in 8 cases and vertebral involvement in 6 cases.In the 9 cases,the X-ray films and CT displayed bony destruction,hyperostosis,small sequestra,and intervertebral space narrowing.Of 18 patients with AIDS,costal lesions were found in 3 cases in which the CT showed expandable bony destruction.Of 18 patients with AIDS,ilium and cacroihac joint lesions were found in 1 case in which the X-ray films and CT showed bony destruction,sequestra,and joint widening.Of 18 patients with AIDS,chronic pyogenic osteomyelitis of femur was found in 1 case in which the X-ray films showed bony destruction,hyperostosis osteosclerosis,and periosteal reaction.Conclusion The X-ray and CT features of soft tissue and bone infections secondary to AIDS are characterized.The X-ray and CT are useful tools to early diagnose soft tissue and bone infections secondary to AIDS. Key words: Acquired immunodeficiency syndrome; Muscle; skeleton; Infection; Tomography; X-ray computed; Radiography

Soft tissue and bone infection involving the foot is one of the most common long-term complications of diabetes mellitus, implying a serious impairment in quality of life for patients in the advanced stages of the disease. Neuropathic osteoarthropathy often coexists and differentiating between these two entities is commonly challenging, but crucial, as the management may differ substantially. The importance of correct diagnosis cannot be understated and effective management requires a multidisciplinary approach owing to the complicated nature of therapy in such patients. A missed diagnosis has a high likelihood of major morbidity for the patient, including limb amputation, and over-diagnosis results in a great socioeconomic challenge for healthcare systems, the over-utilization of healthcare resources, and the unwise use of antibiotics. Diagnosis is largely based on clinical signs supplemented by various imaging modalities such as radiography, MR imaging, and hybrid imaging techniques such as F-18 fluorodeoxyglucose-positron emission tomography. In the interests of the management of diabetic foot complications, this review article is aimed on the one hand at providing radiologists with important clinical knowledge, and on the other hand to equip clinicians with relevant radiological semiotics.

The group G streptococcus has surfaced in the past 10 to 15 years as an important opportunistic and nosocomial pathogen. Although more precise organism recognition accounts for a portion of these cases, there can be little doubt that the group G streptococcus has become a more prevalent pathogen. Commercial kits, utilizing staphylococcal coagglutination or latex agglutination, are now available, affording all clinical laboratories the opportunity to identify this organism easily. Published reviews encompassing the experiences of a single institution or even several institutions affiliated with a single medical center, particularly as they were influenced by referral patterns, did not reflect the broad scope of infections that we discovered by extending our survey into the community, beyond the medical center complex and its immediate affiliated hospitals. Although malignancy is the single most obvious background factor, alcoholism and diabetes are also important host determinants of infection. Skin and soft-tissue infections (and surface sources of infection) are equally important among patients with or without the element of malignancy. Polymicrobial infection, including polymicrobial bacteremia, is an important feature, with S. aureus infections accounting for most of these cases, relating to the skin and soft tissue sources of infections so commonly seen. We saw a panorama of problems including endocarditis, septic arthritis, pleuropulmonary infections, bone and joint infections, puerperal sepsis and neonatal infection, peritonitis and ophthalmitis; we also saw a significant number of patients with bacteremia and no apparent primary source of infection. Response to antibiotic therapy was dictated by the nature of the underlying diseases, and individuals without a background of malignant disease did well, particularly those with skin and soft-tissue infections. While the literature suggests that patients with endocarditis and septic arthritis due to this organism respond poorly to antibiotic therapy, implying that such failures relate to in vitro antibiotic phenomena, we preferred to examine the problem from the viewpoint of the host(s) involved. Subacute endocarditis and acute endocarditis due to the group G streptococcus may be clinically separable, and thus require separate therapeutic approaches. In patients with septic arthritis, prosthetic devices, prior joint disease and immunosuppressive diseases and therapy often adversely influence the response to antibiotic therapy.(ABSTRACT TRUNCATED AT 400 WORDS)

To effectively evaluate musculoskeletal infection, radiologists and nuclear medicine physicians require a thorough understanding of the wide variety of causative organisms, clinical presentations, radiological signs and relevant treatments. In addition and perhaps most importantly they need to be able to bring this information together and form a logical, relevant report which will guide the clinician in patient management. This chapter focuses on each of these subjects with respect to osteomyelitis, septic arthritis and soft tissue infections. Specific clinical scenarios with characteristic imaging and clinical findings such as spinal infection, prosthetic joint infection and the diabetic foot are also discussed.