Necrotizing 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.

Background Polymicrobial results from conventional cultures in bone and soft tissue infections have generally been reported as independent co-occurrences (i.e. assuming no relationship or interaction between species). The objective of this study was to identify non-random (dependent) co-occurrence in bone and soft tissue infections. Methods We used single center Theradoc (Premiere Inc., Charlotte, NC) data on microbiology specimens collected over a decade (4/2010 to 4/2020). We included only tissue, fluid and swab specimens identified as being obtained from bone, skin, soft tissue or a wound during a patient’s first episode of infection. Blood and liver biopsy specimens were excluded. Patterning involving >2 organisms was examined with factor analysis. Analyses were done with R version 3.6.1. Threshold p-values were adjusted for multiple comparisons, often to p< 0.001. Results Polymicrobial culture results were seen much more frequently in the foot (76%) and sacrum (78%) than specimens from other locations (43%). The highest Shannon diversity index was seen in sacral specimens, followed by foot and leg specimens. Pseudomonas aeruginosa and E. coli was found more frequently in sacral bone and soft tissue specimens, while S. aureus was found most often in the spine bone and foot bone and soft tissue. Corynebacterium was found more frequently in foot bone (23%) and foot soft tissue (18%) than in non-foot soft tissue specimens (11%). Analysis of pairwise species co-occurrences in foot specimens (n=765) demonstrated that S. aureus made significantly less frequent the presence of Bacteroides, Enterobacter, and other staphylococcal species (Table 1). Analysis of non-foot soft tissue specimens (n=2,647) confirmed this pairwise associations and suggested three patterns (Table 2): A, polymicrobial without S. aureus; B, Enterococcus + gram negatives; and C, streptococcal. Table 1. Pairwise co-occurrences between species in bone and soft tissue specimens from foot infections (n=765). Factor analysis results demonstrating species associated with three polymicrobial patterns in soft tissue infection specimens. Blue denotes positive association (more often occurring as part of the pattern), red or grey denotes negative associations (less often occurring as part of the pattern). Numbers denote factor weights, a measure of the strength of the association. Conclusion Species incidence and diversity vary by location and tissue type. The many non-random occurrences found suggest complex interrelationships between microbes in soft tissue and bone infections, including organisms often classified as non-pathogens. Further study may further characterize these relationships and aid in antibiotic selection. Disclosures All Authors: No reported disclosures

Soft tissue and wound infections due to Enterococcus spp. are increasing worldwide with current need to understand the epidemiology of the Enterococcal infections of wounds. Hence, we have looked into the distribution of Enterococcus spp. responsible for causing wound and soft tissue infections among trauma patients, its antibiotic resistance pattern and how it affects the length of hospital stay and mortality. A laboratory cum clinical-based study was performed over a period of 3 years at a level I trauma center in New Delhi, India. Patients with Enterococcal wound and soft tissue infections were identified using the hospital data base, their incidence of soft tissue/wound infections calculated, drug resistance pattern and their possible risk factors as well as outcomes analyzed. A total of 86 non-repetitive Enterococcus spp. was isolated of which E. faecium were maximally isolated 48 (56%). High level of resistance was seen to gentamicin HLAR in all the species of Enterococcus causing infections whereas a low level resistance to vancomycin and teicoplanin was observed among the isolates. Longer hospital stay, repeated surgical procedure, prior antibiotic therapy and ICU stay were observed to associate with increased morbidity (P < 0.05) and hence, more chances of infections with VRE among the trauma patients. The overall rate of wound and soft tissue infections with Enterococcus sp. was 8.6 per 1,000 admissions during the study period. Enterococcal wound infection is much prevalent in trauma care facilities especially in the ICUs. Here, a microbiologist can act as a sentinel, help in empirical therapeutic decisions and also in preventing such infections.

152-OR: The Infected Diabetic Foot—The MRSA Incidence, Conversion of Non-MRSA to MRSA Pathogens, and Reinfection in Soft Tissue and Bone Infections

BackgroundPasteurella multocida is a gram-negative pathogen commonly associated with soft tissue infections caused by bites or scratches from household animals. However, P. multocida infections have been reported without prior zoonotic exposure or associated soft tissue or skin infection in immunocompromised individuals.CaseA 73-year-old patient with history significant for multiple malignancies including lung cancer presented to the emergency department with a fever, chills, and rigor. Patient denied any zoonotic exposure and did not have any soft tissue or skin structure infection. Laboratory testing and imaging revealed sepsis secondary to pneumonia and further lower respiratory cultures grew Pasteurella. Subsequent laboratory cultures indicated P. multocida bacteremia.ConclusionThis case aims to advance awareness of the possibility of P. multocida infection in patients who do not have any known zoonotic exposure or identifiable skin or soft tissue infection. Nasopharyngeal colonization in immunocompromised individuals could be a source for invasive infection. Patients who have a pre-existing lung disease are susceptible for developing Pasteurella pneumonia, which can serve as the source of bacteremia.

Cutaneous Mycobacterium chelonae infection presenting clinically as a mycetoma

The present study has 3 aims: (a) to characterize the clinical and pathological features of diabetic foot infections, (b) to show the range of clinical presentations of moderate infections, and (c) to analyze the different behavior of diabetic foot osteomyelitis regarding to its clinical presentation. A definitive diagnosis of the type of infection was made based on intraoperative findings and histopathology. Diabetic foot infections were classified into 2 types: soft tissue and bone infections. Mild infections were always superficial. Severe infections included 75% of necrotizing soft tissue infections. Moderate infections showed ample range of clinical presentations. Eighty-one patients presented osteomyelitis. Osteomyelitis was further classified as follows: osteomyelitis without ischemia and without soft tissue involvement (class 1), osteomyelitis with ischemia without soft tissue involvement (class 2), osteomyelitis with soft tissue involvement (class 3), and osteomyelitis with ischemia and soft tissue involvement (class 4). Forty-eight patients (59.3%) with osteomyelitis underwent conservative surgery, 32 (39.5%) had minor amputations including 9 open transmetatarsal amputations, and there was 1 (1.2%) major amputation. The characterization of osteomyelitis into 4 classes showed a statistically significant trend toward increased severity and increased amputation rate and mortality. In conclusion, the clinical presentation of foot infections in diabetic patients is very heterogeneous and can be classified into soft tissue infections (cellulitis, superficial and deep abscesses, and necrotizing soft tissue infections) and osteomyelitis, which was the most frequent type of infection found in the author's series. Their division into 4 classes showed a statistically significant trend toward increased severity, amputation rate, and mortality. The diagnosis of deep soft tissue infections associated with osteomyelitis may be difficult to achieve before surgery.

29-Year-Old Woman With Fever and Bilateral Lower Extremity Lesions

To study features and risk factors of soft tissue's invasive streptococcal infection in surgical unit's patients: a) emm-types of the most often recovered streptococcus; b) human immune response for streptococcal antigens (streptolysin-O and the group A carbohydrate antigen); c) main patient's conditions that complicate the course of soft tissue's streptococcal infection. 101 surgical unit's patients with soft tissue's infection, which group A streptococcal (GAS) nature, were examined. Emm-types were determined by comparison ofemm gene sequenced part with data of CDC Streptococcus Laboratory. ASO and specific anti-group-carbohydrate IgM were measured with photometry and ELISA4 accordingly. Patient's personal data were analyzed by standard statistical programs. Among 34 emm-types of all streptococcal isolates emm28 and emm64 were registered only in invasive infection. Emm-types 1, 49, 60, 66, 77, 84, 88 were most often. Among 23 sera from invasive GAS-infection's patients, 15(65%) were ASO-negative, 6 (26%) were ASO-low-positive, and 2 (8%) were positive, but negative for the anti-group-A-carbohydrate IgM. Lower levels of the humoral immune response as well as risk factors such as trauma, alcoholism, diabetes, chronic venous insufficiency contributed to development of severe forms of GAS-infection. The main streptococcal emm-types for soft tissue's invasive GAS infection in one of Moscow surgical unit's patients in 2008-2011 were registered.

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

Background Up to 40% of hospitalized patients receive extended-spectrum (ES) antibiotics despite low risk of multidrug-resistant organism (MDRO) infection, increasing the risk for adverse effects and future resistance. We evaluated whether computerized physician order entry (CPOE) prompts providing patient-specific MDRO risk estimates could reduce ES antibiotic use compared to routine stewardship practices in patients hospitalized with skin and soft tissue (SST) infections. Methods This 92-hospital cluster-randomized trial compared CPOE prompts providing patient-specific absolute risk estimates for MDRO SST infection and recommending standard-spectrum antibiotics for risk &amp;lt; 10% vs. routine stewardship. Trial population: adults treated with antibiotics for SST infection in non-ICUs in the first 3 days of admission (empiric period). Prompts were triggered if ES antibiotics were ordered. Trial periods: 12-month Baseline (Jan 2019-Dec 2019); 5-month Phase-in (Aug 2022–Dec 2022); 12-month Intervention (Jan 2023-Dec 2023). Primary outcome: ES antibiotic days of therapy (ES-DOT) per patient per empiric day; secondary outcome was anti-pseudomonal DOT per empiric day. Unadjusted, as-randomized analyses used (1) generalized linear mixed effects models to assess differences in ES-DOT rates across intervention and baseline periods between groups, clustering by patient, hospital, and period and (2) proportional hazards models to assess safety outcomes: days to ICU transfer and hospital LOS. Results We randomized 92 hospitals in 15 states. Across the baseline and intervention periods there were 60,654 and 57,655 non-ICU patients with skin and soft tissue infection in the routine and CPOE prompt groups, respectively. The CPOE prompt group had a 28% reduction in ES-DOT compared to routine care (rate ratio 0.72 [95% CI 0.67-0.79], p&amp;lt; 0.001). Anti-pseudomonal DOT was reduced by 28% (Table, Figure 1) without significant differences in LOS or ICU transfers. Conclusion INSPIRE CPOE prompts providing patient-specific MDRO risk estimates recommending standard spectrum antibiotics in low risk patients significantly reduced empiric ES prescribing in adults admitted with skin and soft tissue infection. Disclosures Ken Kleinman, ScD, Xttrium Laboratories: Conducting studies in which participating hospital patients received contributed antiseptic products outside the submitted work Richard Platt, MD, MSc, GlaxoSmithKline: Contract to academic department|Janssen: Contract to academic department|Pfizer: Contract to academic department Susan Huang, MD, MPH, Xttrium Laboratories: Conducting studies in which participating hospital patients received contributed antiseptic products outside the submitted work

Surgical hazards posed by marine and freshwater animals in Florida

IntroductionThere are currently limited data regarding the clinical and economic significance of skin and soft tissue infections (SSTI) and bone and joint infections in Australian people who inject drugs (PWID).MethodsRetrospective cohort study in adult PWID admitted to Monash Health, a large heath care network with six hospitals in Victoria, Australia. Inpatients were identified using administrative datasets and International Classification of Disease (ICD-10) coding for specific infection-related conditions. Cost analysis was based on mean ward, intensive care and hospital-in-the-home (HITH) lengths of stay. Spinal infections and endocarditis were excluded as part of previous studies.ResultsA total of 185 PWID (61 female, 124 male, median age 37) meeting the study criteria were admitted to Monash Health between January 2010 and January 2021. Admitting diagnoses included 78 skin abscesses, 80 cellulitis, 17 septic arthritis, 4 osteomyelitis, 3 thrombophlebitis and 1 each of necrotising fasciitis, vasculitis and myositis. Pain (87.5%) and swelling (75.1%) were the most common presenting complaints. Opioids (67.4%) and methamphetamine (37.5%) were the most common primary drugs injected. Almost half (46.5%) of patients had concurrent active hepatitis C (HCV) infection on admission. Hepatitis B (HBV) and Human Immunodeficiency Virus (HIV) were uncommon. The most significant causative organism was methicillin-susceptible Staphylococcus aureus (24.9%). In 40.0% (74/185) no organism was identified. Patients required a median acute hospital stay of 5 days (2–51 days). There were 15 patients admitted to the intensive care unit (ICU) with median duration 2 days. PICC line insertion for antibiotics was required in 16.8% of patients, while 51.4% required surgical intervention. Median duration of both oral and IV antibiotic therapy was 11 days. Almost half (48.6%) of patients were enrolled in an opioid maintenance program on discharge. Average estimated expenditure was AUD $16, 528 per admission.ConclusionSkin and soft tissue and joint infections are a major cause of morbidity for PWID. Admission to hospital provides opportunistic involvement of addiction specialty services.

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.

Background Actinotignum schaalii is a gram-positive rod that is a fastidious commensal of the urogenital tract. Infections with A. schaalii are underdiagnosed previously because phenotypic methods fail to identify it. Both MALDI-TOF mass spectrometry and 16S rRNA sequencing allow definitive identification of this opportunistic emerging pathogen. A. schaalii is an infrequent but important cause of UTIs in the elderly, particularly with urological abnormalities. The spectrum of invasive disease caused by A. schaalii is not well characterized; however, it has been isolated in severe infections including necrotizing skin and soft tissue infections, bacteremia, osteomyelitis, and endocarditis. We used a population-based approach to characterize and describe the clinical and microbiological features of invasive A. schaalii infections in our region. Methods All adult and pediatric cases enrolled had microbiological isolates of Actinotignum schaalii recovered from blood cultures, sterile fluids and tissue cultures from Jan 2012 to Dec 2020 by APL, a regional centralized microbiology laboratory serving the Calgary Zone in Alberta, Canada. Clinical data were retrieved and linked from administrative health databases, chart review and the laboratory information system. Standard descriptive statistics were used. Results We identified 84 unique A. schaalii infections, 35 were from bloodstream, 32 soft tissue, 7 post-operative infections. Median age and Charslon comorbidity score was higher in BSI. 54.3% of patient with BSI had a genitourinary pathology, with 51.4% caused by a complicated urinary infection, while soft and skin tissue infections caused 65.3% of non-BSI. Using EUCAST MIC cut-offs, 48% and 100% of the isolates were resistant to clindamycin and metronidazole, respectively. In contrast, all specimens were susceptible to penicillin. Hospitalization and 90-days mortality were higher in the BSI group. Conclusion A. schaalii is an anaerobic opportunistic pathogen that can cause life-threatening invasive infections, particularly in older adults with underlying genitourinary pathology. BSI were associated with higher rates of hospitalization and mortality. In contrast, patients with A. schaalii isolated from cutaneous sources were younger and had better clinical outcomes. Disclosures All Authors: No reported disclosures