OBJECTIVE: To investigate the functional pathways enriched and differentially expressed genes (DEGs) in peripheral blood mononuclear cells (PBMCs) of patients with gram-positive and gram-negative sepsis. METHODS: Dataset GSE9960 obtained from NCBI GEO database containing PBMC samples from 16 non-infectious systematic inflammatory response syndrome (SIRS) patients, 17 gram-positive septic patients and 18 gram-negative septic patients were included in the study. Functional pathway annotations were conducted by gene set enrichment analysis and weighted gene co-expression network analysis. DEGs were filtered and master DEGs were then validated in PBMCs of gram-positive septic, gram-negative septic and non-infectious SIRS patients. RESULTS: The enriched gene sets in gram-positive sepsis and gram-negative sepsis were significantly different. The results indicated the opposite co-expression networks in SIRS and gram-negative sepsis, and the entirely different co-expression networks in gram-positive and gram-negative sepsis. Furthermore, we validated that CONCLUSIONS The results indicate that there are differences in the mechanism and pathogenesis of gram-positive and gram-negative sepsis, which may provide potential markers for sepsis diagnosis and empirical antimicrobial therapy.
Biomarkers/analysis* ; Gene Expression Profiling ; Gram-Negative Bacterial Infections/physiopathology* ; Gram-Positive Bacterial Infections/physiopathology* ; Humans ; Leukocytes, Mononuclear/pathology* ; Sepsis/physiopathology*

Aerococcus viridans, a catalase-negative gram-positive coccus rarely causing bacteremia, was isolated from blood cultures of a 52-yr-old man under the gran-ulocytopenic condition. The isolate showed the typical characteristics of A. viridans, i.e., tetrad arrangements in gram stain, positive pyrrolidonyl aminopeptidase (PYR) and negative leucine aminopeptidase (LAP) reactions, and no growth at 45 degrees C.The isolate was revealed to be highly resistant to penicillin, erythromycin, clindamycin, and ceftriaxone, although most strains of A. viridans isolated from the previously reported patients were susceptible to penicillin and other commonly used antibiotics. Even though A. viridans is rarely associated with human infections, it could be a potential causative agent of bacteremia, especially in immunocompromised patients.
Agranulocytosis/*complications/microbiology/physiopathology ; Bacteremia/*complications/microbiology/physiopathology ; Ceftriaxone/pharmacology ; Clindamycin/pharmacology ; *Drug Resistance, Multiple, Bacterial ; Erythromycin/pharmacology ; Gram-Positive Bacterial Infections/*complications/microbiology/physiopathology ; Humans ; Male ; Middle Aged ; Penicillins/*pharmacology ; Streptococcaceae/*drug effects/isolation & purification