Streptococcal skin infections

Skin microbiome and causal relationships in three dermatological diseases: Evidence from Mendelian randomization and Bayesian weighting

BACKGROUND

Atopic dermatitis (AD), psoriasis (PSO), rosacea, and other related immune skin diseases are affected by multiple complex factors such as genetic and microbial components. This research investigates the causal relationships between specific skin microbiota and these diseases by using Mendelian randomization (MR), and Bayesian weighted Mendelian randomization (BWMR).

METHODS

We utilized genome-wide association study (GWAS) data to analyze the associations between various skin bacteria and three dermatological diseases. Single nucleotide polymorphisms (SNPs) served as instrumental variables (IVs) in MR methods, including inverse variance weighted (IVW), and MR Egger. BWMR was employed to validate results and address pleiotropy.

RESULTS

The IVW analysis identified significant associations between specific skin microbiota and dermatological diseases. ASV006_Dry, ASV076_Dry, and Haemophilus_Dry were significantly positively associated with AD, whereas Kocuria_Dry was negatively associated. In PSO, ASV005_Dry was negatively associated, whereas ASV004_Dry, Rothia_Dry, and Streptococcus_Moist showed positive associations. For rosacea, ASV023_Dry was significantly positively associated, while ASV016_Moist, Finegoldia_Dry, and Rhodobacteraceae_Moist were significantly negatively associated. These results were corroborated by BWMR analysis.

CONCLUSION

Bacterial species such as Finegoldia, Rothia, and Streptococcus play crucial roles in the pathogenesis of AD, PSO, and rosacea. Understanding these microbial interactions can aid in developing targeted treatments and preventive strategies, enhancing patient outcomes and quality of life.

Laboratory evaluation for pediatric patients with suspected necrotizing soft tissue infections: A case-control study

BACKGROUND/PURPOSE

Optimal outcomes for necrotizing soft tissue infections (NSTI) depend on rapid diagnosis and management. The Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score is a validated diagnostic tool for adult NSTI, but its value for children remains unknown. We hypothesized that modification of the LRINEC score may increase its diagnostic accuracy for pediatric NSTI.

METHODS

We performed a case-control study of pediatric patients (age <18) with NSTI (cases) and patients with severe soft tissue infections prompting surgical consultation (controls). The LRINEC score was calculated for cases and controls and compared to a modified, pediatric LRINEC (P-LRINEC) score. Diagnostic accuracy was analyzed through receiver operating characteristic (ROC) curves.

RESULTS

From 2010 to 2014, 20 cases and 20 controls were identified at two children's hospitals. Median LRINEC score was 3.5 (1-8) for cases and 2 (1-7) for controls (p=0.03). The P-LRINEC was comprised of serum CRP >20 (sensitivity=95% (95%CI 79-100%)) and serum sodium <135 (specificity=95% (95%CI 82-100%)). Area under ROC curves was 0.70 (95%CI 0.54-0.87) for the LRINEC score and 0.84 (95%CI 0.72-0.96) for the P-LRINEC score (p=0.06).

CONCLUSION

The P-LRINEC is a simplified version of the LRINEC score utilizing only CRP and sodium and may provide superior accuracy in predicting pediatric NSTI.

[Histological diagnosis of lung bacterial necrotizing infections: a study of four fulminant cases]

Nous rapportons les aspects anatomo-cliniques et histologiques de 4 observations d’infection bactérienne pulmonaire associée à des lésions de nécrose extensive, dont l’évolution a été foudroyante en quelques heures (2 cas d’infections à streptocoque béta hémolytique du groupe A, 1 cas d’infection à Staphylococcus aureus et un cas d’infection à Haemophilus influenzae). Ces infections bactériennes nécrosantes extensives (IBNE) sont gravissimes compte tenu de la production de toxines nécrosantes. Les aspects histologiques sont stéréotypés, combinant une nécrose hémorragique extensive et diffuse, des nappes de bactéries et une réaction inflammatoire cellulaire quasi inexistante. Ces infections sont extrêmement rares et elles surviennent sans cause apparente, chez le sujet immunodéficient ou immunocompétent. Elles posent des problèmes de diagnostic différentiel parfois difficile à résoudre en histologie faisant discuter une infection virale associée. Le diagnostic positif repose sur une confontation anatomopathologique et microbiologique.