Correlations of Host and Bacterial Characteristics with Clinical Parameters and Survival in Staphylococcus aureus Bacteremia

Abstract

Staphylococcus aureus bacteremia (SAB) is a frequent, severe condition that occurs in patients of all age groups and affects clinical departments of all medical fields. It is associated with a high mortality rate of 20–30%. In this study, we analyzed patient mortality associated with SAB at our tertiary care university hospital, assessed the clinical management in terms of administered antimicrobial therapy, and determined which factors have an impact on the clinical course and outcome of patients with this disease. We collected clinical data and blood culture isolates of 178 patients diagnosed with SAB between May 2013 and July 2015. For this study, bacteria were cultured and analyzed concerning their phenotype, hemolysis activity, biofilm formation, nuclease activity, prevalence of toxin genes, spa and agr type. Overall mortality was 24.2% and 30-day mortality was 14.6%. Inadequate initial therapy was administered to 26.2% of patients and was associated with decreased survival (p = 0.041). Other factors associated with poor survival were patient age (p = 0.003), agr type 4 (p ≤ 0.001) and pathological leukocyte counts (p = 0.029 if elevated and p = 0.003 if lowered). The type of infection focus, spa clonal complex and enterotoxin genes seg and sei had an impact on severity of inflammation. Our results indicate that mortality and burden of disease posed by SAB are high at our university hospital.

Comprehensive whole genome analysis of Staphylococcus aureus isolates from dairy cows with subclinical mastitis

“…All S. aureus isolates used in the current investigation included leukocidin genes, such as ST97, ST352, lukS-PV, and lukF-PV (ST152 and ST243). This is consistent with research on bovine S. aureus isolates, which discovered leukocidin and leukotoxin genes in the majority of isolates (Wächter et al, 2021) from cows in India. This may explain similar observations from the current study because many of the lukS-PV and lukF-PV genes in our analysis shared the same percentage identity across different S. aureus isolates, suggesting that the gene sequences may be comparable to those of the genome even if they are absent.…”

The natural product, echinatin, protects mice from methicillin-resistant Staphylococcus aureus pneumonia by inhibition of alpha-hemolysin expression

“…Pore-causing alphahemolysin (Hla), also known as a-toxin (AT), is a pore-forming exotoxin produced by almost all virulent strains of the bacterium. The lethal properties of Hla include hemolytic activity, cytotoxicity, dermonecrosis, and other endotoxins (Wächter et al, 2021). Hla-mediated cell death is caused by the formation of a transmembrane pore in the plasma membrane of susceptible cells, allowing leakage of intracellular material, and it has been associated with several S. aureus diseases, including SSTI (Kennedy et al, 2010) and pneumonia (Inoshima et al, 2011).…”

Direct Quantitative Immunochemical Analysis of Autoinducer Peptide IV for Diagnosing and Stratifying Staphylococcus aureus Infections

“…aureus can be stratified into four different groups (agr I, agr II, agr III, and agr IV) according to the sequences of the agrC and agrD genes, which results in four different AIs, which are small (7–9 amino acids) cyclic thiodepsipeptides (the C-terminal carboxylic group forms a thiolactone with the thiol of a Cys) produced in a strain-specific manner . There have been reported clear associations between the agr type and virulence, the ability to form biofilms, and AMR profile. − Hence, higher prevalence of generalized exfoliative syndromes or osteoarticular infections has been associated with agr group IV, , TSS toxin1-producing isolates have been found to belong mainly to agr group III, and higher risk of endocarditis has been associated with infections from agr types I and II. , Other interesting associations have also been recently reported on a study performed with 833 S. aureus strains (785 bacteremia and 48 colonizing strains) collected in Spain over a period of 15 years (2002–2017), pointing at the higher prevalence of agr IV on colonizing strains, agr II on HAIs, and agr I on CAIs, while agr II would be more prevalent in adults, and agr III would be associated with infections in children .…”