Differentiating necrotizing soft tissue infections from cellulitis by soft tissue infectious fluid analysis: a pilot study

Background We conducted this study to evaluate the characteristics of the infectious fluid in soft tissue infection and investigate the utility of the biochemical tests and Gram stain smear of the infectious fluid in distinguishing necrotizing soft tissue infection (NSTI) from cellulitis. Methods This retrospective cohort study was conducted in a tertiary care hospital in Taiwan. From April 2019 to October 2020, patients who were clinically suspected of NSTI with infectious fluid accumulation along the deep fascia and received successful ultrasound-guided aspiration were enrolled. Based on the final discharge diagnosis, the patients were divided into NSTI group, which was supported by the surgical pathology report, or cellulitis group. The t test method and Fisher’s exact test were used to compare the difference between two groups. The receiver–operator characteristic (ROC) curves and area under the ROC curve (AUC) were used to evaluate the discriminating ability. Results Total twenty-five patients were enrolled, with 13 patients in NSTI group and 12 patients in cellulitis group. The statistical analysis showed lactate in fluid (AUC = 0.937) and LDH in fluid (AUC = 0.929) had outstanding discrimination. The optimal cut-off value of fluid in lactate was 69.6 mg/dL with corresponding sensitivity of 100% and specificity of 76.9%. The optimal cut-off value of fluid in LDH was 566 U/L with corresponding sensitivity of 83.3% and a specificity of 92.3%. In addition, albumin in fluid (AUC = 0.821), TP in fluid (AUC = 0.878) and pH in fluid (AUC = 0.858) also had excellent diagnostic accuracy for NSTI. The Gram stain smear revealed 50% bacteria present in NSTI group and all the following infectious fluid culture showed bacteria growth. Conclusions The analysis of infectious fluid along the deep fascia might provide high diagnostic accuracy to differentiate NSTI from cellulitis.

Increase in the Complement Activation Product C4d and the Terminal Complement Complex sC5b-9 Is Associated with Disease Severity and a Fatal Outcome in Necrotizing Soft-Tissue Infection

The hyperinflammatory burden is immense in necrotizing soft-tissue infection (NSTI). The complement system is a key during the innate immune response and may be a promising target to reduce the inflammatory response, potentially improving the clinical outcome. However, complement activation and its association to disease severity and survival remain unknown in NSTI. Therefore, we prospectively enrolled patients with NSTI and sampled blood at admission and once daily for the following 3 days. Plasma C4c, C4d, C3bc, and C3dg and the terminal complement complex (TCC) were evaluated using ELISA techniques. In total, 242 patients were included with a median age of 62 years, with a 60% male predominance. All-cause 30-day mortality was 17% (95% confidence interval [CI] 13–23) with a follow-up of &#x3e;98%. C4c and C3dg were negatively correlated with Simplified Acute Physiology Score II (<i>Rho</i> −0.22, <i>p</i> &#x3c; 0.001 and <i>Rho</i> −0.17, <i>p</i> = 0.01). Patients with septic shock (<i>n</i> = 114, 47%) had higher levels of baseline TCC than those in non-shock patients (18 vs. 14, <i>p</i> &#x3c; 0.001). TCC correlated with the Sequential Organ Failure Assessment (SOFA) score (<i>Rho</i> 0.19, <i>p</i> = 0.004). In multivariate Cox regression analysis (adjusted for age, sex, comorbidity, and SOFA score), high baseline C4d (&#x3e;20 ng/mL) and the combination of high C4d and TCC (&#x3e;31 arbitrary units/mL) were associated with increased 30-day mortality (hazard ratio [HR] 3.26, 95% CI 1.56–6.81 and HR 5.12, 95% CI 2.15–12.23, respectively). High levels of both C4d and TCC demonstrated a negative predictive value of 0.87. In conclusion, we found that in patients with NSTI, complement activation correlated with the severity of the disease. High baseline C4d and combination of high C4d and TCC are associated with increased 30-day mortality. Low baseline C4d or TCC indicates a higher probability of survival.

Empyema necessitans – An unusual cause of necrotising fasciitis of the breast

Necrotising fasciitis is a dreaded aggressive soft tissue infection that can cause extensive tissue necrosis. It may arise in the breast where its diagnosis may not readily be evoked.

Beta-Lactam vs. Fluoroquinolone Monotherapy for Pseudomonas aeruginosa Infection: A Systematic Review and Meta-Analysis

Introduction: Pseudomonas aeruginosa (PA) is a leading cause of healthcare-associated infections. A variety of antibiotic classes are used in the treatment of PA infections, including beta-lactams (BLs) and fluoroquinolones (FQs), given either together in combination therapy or alone in monotherapy. A systematic review and meta-analysis were performed to evaluate the therapeutic efficacy of BL agents versus FQ agents as active, definitive monotherapy in PA infections in adults. Methods: Comprehensive literature searches of the Medline and Scopus electronic databases, alongside hand searches of the Cochrane Database of Systematic Reviews, PubMed, and Google Scholar, were performed without a time restriction to identify studies published in English comparing BL and FQ agents given as monotherapy for PA infection in hospitalized adults for which mortality, bacteriological eradication, or clinical response was evaluated. One reviewer screened search results based on pre-defined selection criteria. Two reviewers independently assessed included studies for methodological quality using NIH assessment tools. Two fixed-effects meta-analyses were performed. Results: A total of 368 articles were screened, and six studies involving 338 total patients were included in the meta-analysis. Upon evaluation of methodological quality, two studies were rated good, three fair, and one poor. A meta-analysis of three studies demonstrates FQ monotherapy is associated with significantly improved survival compared to BL monotherapy for patients with PA bacteremia (OR, 3.65; 95% CI, 1.27–10.44; p = 0.02). A meta-analysis of three studies demonstrates FQ monotherapy is associated with equivalent bacteriological eradication compared to BL monotherapy for PA pneumonia or skin and soft tissue infection (RD, 0.07; 95% CI, −0.09 to 0.24; p = 0.39). Conclusion: The meta-analyses demonstrate FQ monotherapy significantly improves survival in PA bacteremia and is associated with similar rates of bacteriological eradication in pneumonia and skin and soft tissue infection caused by PA compared to BL monotherapy. However, more research is needed to make meaningful clinical recommendations.