Biology subjects

Andreoni, F.

Publications and source records attributed to Andreoni, F..

4 recordsLinked to original sources

bioRxiv2022

Group A Streptococcus antibiotic tolerance in necrotizing fasciitis

ObjectivesGroup A Streptococcus (GAS) necrotizing fasciitis (NF) is a difficult-to-treat bacterial infection associated with high morbidity and mortality despite extensive surgery and targeted antibiotic treatment. Bacteria surviving prolonged antibiotic exposure without displaying genetic resistance, so-called persisters, are associated with difficult-to-treat infections, such as GAS-NF. In the present study, we investigated the presence of persistent GAS in tissue freshly debrided from three NF patients and examined more in depth the persisters phenomenon in GAS-NF clinical isolates. MethodsTime-lapse imaging of freshly isolated GAS-NF clinical isolates, the image analysis software ColTapp and antibiotic challenge-based persisters assays were used to assess the presence of persisters. ResultsWe show for the first time that GAS recovered directly from freshly debrided NF patients tissue are characterized by increased colony appearance time heterogeneity, indicating the presence of persisters. Acidic pH or nutrient stress exposure, mimicking the NF-like environment in vitro, similarly leads to phenotypic heterogeneity resulting in enhanced antibiotic survival and confirming the presence of GAS persisters. ConclusionsGAS persisters are present in the tissue freshly debrided from GAS-NF patients and might be one explanation for antibiotic treatment failure and surgery requirement in GAS-NF. Tailored treatment options, including the use of persisters-targeting drugs, need to be developed to increase GAS-NF therapy success.

microbiology↗

bioRxiv2022

Intervertebral disc cell chondroptosis elicits neutrophil response in Staphylococcus aureus spondylodiscitis

ObjectiveTo understand the pathophysiology of spondylodiscitis due to Staphylococcus aureus, an emerging infectious disease of the intervertebral disc (IVD) and vertebral body with a high complication rate, by combining clinical insights and experimental approaches. DesignClinical data and histological material of nine patients suffering from S. aureus spondylodiscitis were retrospectively collected at a single center. To mirror the clinical findings experimentally, we developed a novel porcine ex vivo model mimicking acute S. aureus spondylodiscitis and assessed the interaction between S. aureus and IVD cells within their native environment. In addition, the inflammatory features underlying this interaction were assessed in primary human IVD cells. Finally, mirroring the clinical findings, we assessed primary human neutrophils for their ability to respond to secreted inflammatory modulators of IVD cells upon S. aureus challenge. ResultsAcute S. aureus spondylodiscitis in patients was characterized by tissue necrosis and neutrophil infiltration. Additionally, the presence of empty IVD cells lacunae was observed. This was mirrored in the ex vivo porcine model, where S. aureus induced extensive IVD cell death, leading to empty lacunae. Concomitant engagement of the apoptotic and pyroptotic cell death pathways was observed in primary human IVD cells, resulting in cytokine release. Among the released cytokines, functionally intact neutrophil-priming as well as broad pro- and anti-inflammatory cytokines known for their involvement in IVD degeneration were found. ConclusionsIn patients as well as ex vivo in a novel porcine model, S. aureus spondylodiscitis infection caused IVD cell death, resulting in empty lacunae, which was accompanied by release of inflammation markers and recruitment of neutrophils. These findings offer valuable insights into the important role of inflammatory IVD cell death during the onset of spondylodiscitis and potential future therapeutic approaches.

immunology↗

bioRxiv2021

Limited adaptive evolution of Staphylococcus aureus during transition from colonization to invasive infection

Staphylococcus aureus carriage is a risk factor for invasive infections. Unique genetic elements favoring the transition from colonizing to invasive phenotype have not yet been identified and phenotypic traits are understudied. We therefore assessed pheno- and genotypic profiles of eleven S. aureus isolate pairs sampled from colonized patients simultaneously suffering from invasive S. aureus infections. Ten out of 11 isolate pairs presented the same spa and MLST suggesting colonization as origin for the invasive infection. Systematic analysis of colonizing and invasive isolate pairs showed similar adherence, hemolysis and reproductive fitness properties, minimal genetic differences, identical antibiotic tolerance and bacterial virulence in Galleria mellonella. Our results provide insights into the similar phenotype associated with limited adaptive genetic evolution between the colonizing and invasive isolates. Disruption of the physical barriers mucosa or skin were identified in the majority of patients further emphasizing colonization as a major risk factor for invasive disease. ImportanceS. aureus is a major pathogen of humans causing a wide range of disease. The failure to develop a vaccine and antibiotic warrant the exploration of novel treatment strategies. Asymptomatic colonization of the human nasal passages is a major risk factor for invasive disease and decolonization procedures have shown efficacy in preventing invasive infections. However, the transition of S. aureus from a benign colonizer of the nasal passages to a major pathogen is not well understood and host as well as bacterial properties have been discussed as being relevant for this behavioral change. We conducted a thorough investigation of patient-derived strain pairs reflecting colonizing and invasive isolates in a given patient. Although we identified limited genetic adaptation in certain strains as well as slight differences in adherence capacity of colonizing and invasive isolates, our work suggests that barrier breaches are a key event in the disease continuum of S. aureus.

microbiology↗

bioRxiv2021

Assessing antibiotic tolerance of Staphylococcus aureus derived directly from patients by the Replica Plating Tolerance Isolation System- REPTIS

Antibiotic tolerant Staphylococcus aureus pose a great challenge to clinicians as well as to microbiological laboratories and are one reason for treatment failure. Antibiotic tolerant strains survive transient antibiotic exposure despite being fully susceptible in vitro. Thus, fast and reliable methods to detect tolerance in the routine microbiology laboratory are urgently required. We therefore evaluated the feasibility of the replica plating tolerance isolation system (REPTIS) to detect antibiotic tolerance in S. aureus isolates derived directly from patients suffering from different types of infections and investigated possible connections to clinical presentations and patient characteristics. One hundred twenty-five S. aureus isolates were included. Replica plating of the original resistance testing plate was used to assess regrowth in the zones of inhibition, indicating antibiotic tolerance. Bacterial regrowth was assessed after 24 and 48 hours of incubation and an overall regrowth score (ORS) was assigned. Regrowth scores were compared to the clinical presentation. Bacterial regrowth was high for most antibiotics targeting protein synthesis and relatively low for antibiotics targeting other cellular functions such as DNA-replication, transcription and cell wall synthesis, with the exception of rifampicin. Isolates with a blaZ penicillinase had lower regrowth in penicillin and ampicillin. Low ORSs were more prevalent among isolates recovered from patients with immunosuppression or methicillin-resistant S. aureus (MRSA) isolates. In conclusion, REPTIS is useful to detect antibiotic tolerance in clinical microbiological routine diagnostics. Rapid detection of antibiotic tolerance offers a new diagnostic readout that might allow more tailored treatments in the future.

microbiology↗