Imaging and Laboratory Workup for Hand Infections

High-resolution ultrasound in the evaluation of musculoskeletal 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.

Microbiologic Analysis of Hand Infections: A Prospective Study

Background: Hand infections are a common problem in emergency departments. Staphylococcus aureus is the main pathogen of both hand and blood stream infections. Therefore, the aim of the present study was to evaluate the frequency and impact of bacteremia in patients with hand infections to improve the microbiologic diagnostics. Patients and Methods: A prospective study of 90 patients with acute hand infections without antimicrobial pre-treatment was performed. Blood cultures were taken pre-operatively. If positive, transesophageal echocardiography was performed to rule out infectious endocarditis. Tissue samples were microbiologically processed using standardized culture media. If negative, a broad-spectrum bacterial 16S ribosomal RNA (rRNA) gene polymerase chain reaction (PCR) was applied. The etiology and location of the infection, the length of hospital stay, the number of surgical interventions, and the inflammatory parameters were obtained. Results: Six patients with bacteremia (6.6%) were diagnosed, after animal bites (n = 3) and intra-articular empyema (n = 3). Pathogens included Staphylococcus pettenkoferi, Pasteurella multocida, Staphylococcus epidermidis, Staphylococcus aureus, and Bacteroides pyogenes. No case of infective endocarditis was detected. Patients with bacteremia required more surgical interventions (p = 0.002), had a longer hospital stay (p < 0.001), higher plasma C-reactive protein (CRP; p = 0.016), and a higher age (p = 0.002) compared with those without bacteremia. In 14 cases (15.6%) no pathogen was detected by culture, whereas the subsequent broad-spectrum PCR diagnosed three cases (21.4%). Conclusions: Pre-operative blood cultures in patients with hand infections are important to detect bacteremia as an essential marker of clinical severity. Those blood cultures are indicated after deep animal bites and joint empyema. A precise identification of pathogens is fundamental for an effective treatment of hand infections, for which a 16S rRNA gene PCR can contribute in culture-negative tissue samples.

Necrotizing Fasciitis of the Upper Extremity – A Review

Necrotizing fasciitis is a soft tissue infection that habitually originates from the fascial sheaths, expands at a volant pace, leads to extensive necrosis of the subcutaneous tissues, and eventually ends up in a life-threatening condition with notably elevated amputation and mortality rates. Factors that induce interruption of skin integrity, such as trauma or intravenous drug use, are the most common inciting events. Specific clinical signs heralding its presence are usually absent in the early stages, often resulting in misdiagnosis. Early recognition, prompt and aggressive surgical debridement, antibiotic use, and supportive care constitute the fundamental principles to lean on for a better prognosis. Necrotizing fasciitis of the upper extremity is relatively rare and consequently holds a limited place in the literature. Only a few studies assess it as a separate entity, with most of them being case reports or small case series. We, therefore, performed a review of the current literature, to assemble the dispersed results of different studies and clarify the various aspects of upper limb necrotizing fasciitis. In this systematic review, we present the epidemiological data, the causative events, the most frequent underlying diseases, the risk factors, the amputation and mortality rates, the pathogenic microorganisms, the clinical characteristics, the diagnostic tools, the medical and surgical management concerning necrotizing fasciitis of the upper limb. Finally, the results indicating its differentiation compared to necrotizing fasciitis of other anatomic sites are remarkably highlighted.

[Diagnostic Imaging for Infections of the Hand]

Clinical signs of an infection of the hand can be subtle initially or in a chronic state. But even in a progressive stadium it might be difficult to define an involvement of soft tissue, joint or bone. This review article addresses the diagnostic options of radiologic imaging. Radiographs of the affected region are the basic diagnostics. Sonographics provides information about an abscess or effusion versus diffuse edema and phlegmon. Both are in most situations promptly available. In chronic cases and unclear findings, MRI is of value. With bone involvement and an implant related osteomyelitis suspected, CT is the most valid method.